tellurium and cadmium-telluride

In vivo toxicological studies are currently necessary to analyze the probable dangers of quantum dots (QDs) to the environment and human safety, due to the fast expansion of QDs in a range of applications. Because of its high fecundity, cost-effectiveness, well-defined developmental phases, and optical transparency, zebrafish has long been considered the "gold standard" for biosafety assessment of chemical substances and pollutants. In this review, the advantages of using zebrafish in QD toxicity assessment were explored. Then, the target organ toxicities such as developmental toxicity, immunotoxicity, cardiovascular toxicity, neurotoxicity, and hepatotoxicity were summarized. The hazardous effects of different QDs, including cadmium-containing QDs like CdTe, CdSe, and CdSe/ZnS, as well as cadmium-free QDs like graphene QDs (GQDs), graphene oxide QDs (GOQDs), and others, were emphasized and described in detail, as well as the underlying mechanisms of QDs generating these effects. Furthermore, general physicochemical parameters determining QD-induced toxicity in zebrafish were introduced, such as chemical composition and surface coating/modification. The limitations and special concerns of using zebrafish in QD toxicity studies were also mentioned. Finally, we predicted that the utilization of high-throughput screening assays and omics, such as transcriptome sequencing, proteomics, and metabolomics will be popular topic in nanotoxicology.

Topics: Animals; Cadmium Compounds; Humans; Quantum Dots; Selenium Compounds; Sulfides; Tellurium; Zebrafish; Zinc Compounds

The ecosystem across the globe has been adversely affected due to the adoption of unsustainable growth strategies. Overuse of organic pollutants such as dyes, pesticides, disinfectants, food additives and antibiotics, along with their release into the environment without proper treatment has severely affected the food chain and water bodies, hence ultimately the human race. As the organic contaminants, being non-biodegradable, persist in the environment for a long duration, a sustainable method for the detection of these harmful organic pollutants is essential. For food safety and restoration of ecological balance, simple, non-toxic, cost-effective and environmentally friendly green precursor derived carbon dots (CDs) are favorable as compared to inorganic nanoparticles (CdTe, CdS etc.) and chemically derived CDs. This review covers the summary of the studies devoted to the optical detection of organic pollutants, food additives and antibiotics through green precursor derived CDs, reported during the last few years. The upcoming studies of optical sensing systems with sustainable CDs provide powerful insight towards pollutant detection, as well as act as a future monitoring tool.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Carbon; Ecosystem; Environmental Pollutants; Fluorescent Dyes; Food Additives; Humans; Quantum Dots; Tellurium

In light of potential risks of heavy metal exposure, diverse aptasensors have been developed through the combination of aptamers with nanomaterials for the timely and efficient detection of metals in environmental and biological matrices. Aptamer-based sensors can benefit from multiple merits such as heightened sensitivity, facile production, uncomplicated operation, exceptional specificity, enhanced stability, low immunogenicity, and cost-effectiveness. This review highlights the detection capabilities of nanomaterial-based aptasensors for heavy-metal and metalloid ions based on their performance in terms of the basic quality assurance parameters (e.g., limit of detection, linear dynamic range, and response time). Out of covered studies, dendrimer/CdTe@CdS QDs-based ECL aptasensor was found as the most sensitive option with an LOD of 2.0 aM (atto-molar: 10

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Ions; Metalloids; Metals, Heavy; Nanostructures; Quantum Dots; Tellurium

Topics: Cadmium Compounds; Quantum Dots; Solar Energy; Tellurium

Recent advances in photon counting detection technology have led to significant research interest in X-ray imaging.. As a tutorial level review, this paper covers a wide range of aspects related to X-ray photon counting detector characterization.. The tutorial begins with a detailed description of the working principle and operating modes of a pixelated X-ray photon counting detector with basic architecture and detection mechanism. Currently available methods and techniques for charactering major aspects including energy response, noise floor, energy resolution, count rate performance (detector efficiency), and charge sharing effect of photon counting detectors are comprehensively reviewed. Other characterization aspects such as point spread function (PSF), line spread function (LSF), contrast transfer function (CTF), modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), bias voltage, radiation damage, and polarization effect are also remarked.. A cadmium telluride (CdTe) pixelated photon counting detector is employed for part of the characterization demonstration and the results are presented.. This review can serve as a tutorial for X-ray imaging researchers and investigators to understand, operate, characterize, and optimize photon counting detectors for a variety of applications.

Topics: Cadmium Compounds; Calibration; Equipment Design; Photons; Signal Processing, Computer-Assisted; Spectrometry, X-Ray Emission; Tellurium; X-Rays

The trade-off between resolution and count sensitivity dominates the performance of standard gamma cameras and dictates the need for relatively high doses of radioactivity of the used radiopharmaceuticals in order to limit image acquisition duration. The introduction of cadmium-zinc-telluride (CZT)-based cameras may overcome some of the limitations against conventional gamma cameras. CZT cameras used for the evaluation of myocardial perfusion have been shown to have a higher count sensitivity compared to conventional single photon emission computed tomography (SPECT) techniques. CZT image quality is further improved by the development of a dedicated three-dimensional iterative reconstruction algorithm, based on maximum likelihood expectation maximization (MLEM), which corrects for the loss in spatial resolution due to line response function of the collimator. All these innovations significantly reduce imaging time and result in a lower patient's radiation exposure compared with standard SPECT. To guide current and possible future users of the CZT technique for myocardial perfusion imaging, the Cardiovascular Committee of the European Association of Nuclear Medicine, starting from the experience of its members, has decided to examine the current literature regarding procedures and clinical data on CZT cameras. The committee hereby aims 1) to identify the main acquisitions protocols; 2) to evaluate the diagnostic and prognostic value of CZT derived myocardial perfusion, and finally 3) to determine the impact of CZT on radiation exposure.

Topics: Cadmium Compounds; Cardiac Imaging Techniques; Coronary Artery Disease; Equipment Design; Equipment Failure Analysis; Europe; Evidence-Based Medicine; Gamma Rays; Humans; Radiation Dosage; Radiation Exposure; Radionuclide Imaging; Reproducibility of Results; Sensitivity and Specificity; Tellurium; Zinc

Quantum dots (QDs) are one of the first nanotechnologies to be integrated with the biological sciences that used for imaging or tracking macromolecules/cells in cell/tissue. Because of QDs are important in biomedical and biological applications, identify a variety of synthesis methods to produce QDs with different characteristics also is particularly important. Hence, in this review the authors discussed three methods for synthesis of heavy metal chalcogenide-based QDs for use in biomedical field: (i) Organometallic method for synthesis of QDs consists of three components: precursors, organic surfactants and solvents. The authors also discussed water-solubilisation strategies of synthesised QDs including encapsulation and ligand exchange. (ii) Aqueous synthesis technique using short-chain thiols as stabilising agents is a useful alternative to organometallic synthesis of CdSe, CdS and CdTe QDs. (iii) The third method discussed in this article for QDs synthesis involves the utilise of microorganisms to prepare QDs with controlled size, shape, chemical composition and functionality. The authors also discussed recently new methods for the synthesis of the appropriate QDs for use in biology. In addition, attachment of biomolecules such as antibodies, oligonucleotides on the surface of QDs for specific targeting and different opinions about toxicity of QD have been studied.

Topics: Cadmium Compounds; Chalcogens; Colloids; Nanomedicine; Nanoparticles; Particle Size; Peptides; Photochemistry; Photons; Quantum Dots; Selenium Compounds; Semiconductors; Solubility; Solvents; Sulfides; Surface Properties; Tellurium; Water

Semiconductor quantum dots (QDs) are light-emitting particles on the nanometer scale that have emerged as a new class of fluorescent labels for chemical analysis, molecular imaging, and biomedical diagnostics. Compared with traditional fluorescent probes, QDs have unique optical and electronic properties such as size-tunable light emission, narrow and symmetric emission spectra, and broad absorption spectra that enable the simultaneous excitation of multiple fluorescence colors. QDs are also considerably brighter and more resistant to photobleaching than are organic dyes and fluorescent proteins. These properties are well suited for dynamic imaging at the single-molecule level and for multiplexed biomedical diagnostics at ultrahigh sensitivity. Here, we discuss the fundamental properties of QDs; the development of next-generation QDs; and their applications in bioanalytical chemistry, dynamic cellular imaging, and medical diagnostics. For in vivo and clinical imaging, the potential toxicity of QDs remains a major concern. However, the toxic nature of cadmium-containing QDs is no longer a factor for in vitro diagnostics, so the use of multicolor QDs for molecular diagnostics and pathology is probably the most important and clinically relevant application for semiconductor QDs in the immediate future.

Topics: Biomarkers, Tumor; Cadmium Compounds; Diagnostic Imaging; DNA; Humans; Immunohistochemistry; In Situ Hybridization, Fluorescence; Male; Nanoparticles; Nanotechnology; Neoplasms; Polyethylene Glycols; Prostate; Quantum Dots; Selenium Compounds; Semiconductors; Tellurium

As the number of applications of quantum dots (QDs) grows, the likelihood of exposure increases. Because these metals have the potential for detrimental environmental and health effects, concerns have been raised over our lack of understanding about the fate of these products. Among various types of QDs, cadmium-based quantum dots attract the greatest attention due to their wide applications. To properly assess the potential risk of cadmium-containing QDs, we summarize the current state of academic knowledge on the toxicity of cadmium-based QDs.

Topics: Animals; Cadmium Compounds; Humans; Quantum Dots; Selenium Compounds; Tellurium

Over the past few years, CdTe quantum dots have been demonstrated as powerful probes for biophotonics applications. The aqueous phase synthesis technique remains the best approach to make high quality CdTe QDs in a single-pot process. CdTe QDs prepared directly in the aqueous phase can have quantum yield as high as 80%. In addition, the surface of CdTe QDs prepared using the aqueous phase technique is functionalized with reactive groups that enable them to be directly conjugated with specific ligands for targeted delivery and sensing. In this contribution, we review recent progress in fabricating aqueous CdTe QDs and exploiting their optical properties in novel approaches to biomedical imaging and sensing applications.

Topics: Animals; Cadmium Compounds; Humans; Molecular Imaging; Optics and Photonics; Organic Chemicals; Quantum Dots; Tellurium; Water

The opportunities for photovoltaic (PV) solar energy conversion are reviewed in the context of projected world energy demands for the twenty-first century. Conventional single-crystal silicon solar cells are facing increasingly strong competition from thin-film solar cells based primarily on polycrystalline absorber materials, such as cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). However, if PVs are to make a significant contribution to satisfy global energy requirements, issues of sustainability and cost will need to be addressed with increased urgency. There is a clear need to expand the range of materials and processes that is available for thin-film solar cell manufacture, placing particular emphasis on low-energy processing and sustainable non-toxic raw materials. The potential of new materials is exemplified by copper zinc tin sulphide, which is emerging as a viable alternative to the more toxic CdTe and the more expensive CIGS absorber materials.

Topics: Cadmium Compounds; Conservation of Energy Resources; Conservation of Natural Resources; Copper; Electricity; Equipment Design; Gallium; Indium; Photochemical Processes; Selenium; Silicon; Solar Energy; Tellurium

Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II-VI or III-V of the periodic table, such as cadmium telluride (CdTe) or cadmium selenium (CdSe) forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus.

Topics: Animals; Bacteria; Cadmium Compounds; Fungi; Microbial Sensitivity Tests; Quantum Dots; Selenium Compounds; Tellurium; Viruses

Water-soluble colloidal semiconductor quantum dots (QDs) as a new class of fluorescent probes with excellent optical properties have attracted considerable attention in bioapplications. Because of the large surface-to-volume ratio of QDs, especially in the case of QDs passivated with organic ligands, the photoluminescence (PL) of QDs is sensitive to the environmental conditions. Generally, the PL behavior of intracellular QDs is more complicated than that in solutions due to the complex cellular environment. In this review, the environmental influence on the PL behavior of intracellular thiol-capped CdTe QDs, such as the time-dependent spectral blueshift, photobleaching and lifetime shortening, is introduced and its mechanisms are discussed.

Topics: Cadmium Compounds; Cells, Cultured; Image Enhancement; Luminescent Measurements; Materials Testing; Microscopy, Fluorescence; Quantum Dots; Sensitivity and Specificity; Sulfhydryl Compounds; Tellurium

Quantum dots (QDs) are nanoscale inorganic particles generally composed of II-VI and III-V elements. Recently, QDs have received great interest in biological applications because of their unique and fascinating optical properties. In this short review, we introduce the synthesis of luminescent QDs in the aqueous phase and characterize certain fundamental parameters of luminescent QDs synthesized in the aqueous phase by fluorescence correlation spectroscopy (FCS), which include, for example, their dynamic diameters and surface charges. Meanwhile, combining with some ensemble spectroscopy techniques, we applied FCS to investigate the quenching process and mechanism of heavy metal ions (e.g., Ag(+)) on CdTe QDs, as well as the aggregation and subsequent photoactivation process of 3-mercaptopropionic acid-capping CdTe QDs induced by laser irradiation. Our preliminary results demonstrate that FCS is a sensitive and efficient tool to characterize fluorescent nanoparticles, such as QDs, at the single-molecule detection level.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Crystallization; Fluorescent Dyes; Lasers; Light; Luminescence; Nanoparticles; Nanotechnology; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium; Time Factors; Water

The novel optical and electrical properties of luminescent semiconductor nanocrystals are appealing for ultrasensitive multiplexing and multicolor applications in a variety of fields, such as biotechnology, nanoscale electronics, and opto-electronics. Luminescent CdSe and CdTe nanocrystals are archetypes for this dynamic research area and have gained interest from diverse research communities. In this review, we first describe the advances in preparation of size- and shape-controlled CdSe and CdTe semiconductor nanocrystals with the organometallic approach. This article gives particular focus to water soluble nanocrystals due to the increasing interest of using semiconductor nanocrystals for biological applications. Post-synthetic methods to obtain water solubility, the direct synthesis routes in aqueous medium, and the strategies to improve the photoluminescence efficiency in both organic and aqueous phase are discussed. The shape evolution in aqueous medium via self-organization of preformed nanoparticles is a versatile and powerful method for production of nanocrystals with different geometries, and some recent advances in this field are presented with a qualitative discussion on the mechanism. Some examples of CdSe and CdTe nanocrystals that have been applied successfully to problems in biosensing and bioimaging are introduced, which may profoundly impact biological and biomedical research. Finally we present the research on the use of luminescent semiconductor nanocrystals for construction of light emitting diodes, solar cells, and chemical sensors, which demonstrate that they are promising building blocks for next generation electronics.

Topics: Cadmium Compounds; Luminescence; Nanoparticles; Nanotechnology; Quantum Dots; Selenium Compounds; Surface Properties; Tellurium

The one-dimensional (1-D) nanostructures of cadmium chalcogenides (Il-VI: CdSe, CdTe), InP and GaAs (III-V), and the ternary chalcopyrites CulnS2, CulnSe2, and CulnTe2 (I-III-VI2) are the candidate semiconductors of interest as absorber layers in solar cells. In the confinement regime (approximately 1-10 nm) of these 1-D nanostructures, the electronic energy levels are quantized so that the oscillator strength and the resultant absorption of solar energy are enhanced. Moreover, the discrete energy levels effectively separate the electrons and holes at the two electrodes or at the interfaces with a polymer in a hybrid structure, so that an oriented and 1-D nanostructured absorber layer is expected to improve the conversion efficiency of solar cells. The intrinsic anisotropy of Il-VI and l-lll-VI2 crystal lattices and the progress in various growth processes are assessed to derive suitable morphological features of these 1-D semiconductor nanostructures. The present status of research in nanorod-based solar cells is reviewed and possible routes are identified to improve the performance of nanorod-based solar cells. Finally, the characteristics of nanorod-based solar cells are compared with the dye-sensitized and organic solar cells.

Topics: Anisotropy; Cadmium Compounds; Crystallization; Equipment Design; Materials Testing; Microscopy, Atomic Force; Models, Chemical; Nanostructures; Nanotechnology; Nanotubes; Oscillometry; Polymers; Selenium Compounds; Semiconductors; Solar Energy; Sunlight; Tellurium

Since Nuclear Medicine diagnostic applications are growing fast, room temperature semiconductor detectors such CdTe and CdZnTe either in the form of single detectors or as segmented monolithic detectors have been investigated aiming to replace the NaI scintillator. These detectors have inherently better energy resolution that scintillators coupled to photodiodes or photomultiplier tubes leading to compact imaging systems with higher spatial resolution and enhanced contrast. Advantages and disadvantages of CdTe and CdZnTe detectors in imaging systems are discussed and efforts to develop semiconductor-based planar and tomographic cameras as well as nuclear probes are presented.

Topics: Cadmium Compounds; Equipment Design; Gamma Cameras; Humans; Nuclear Medicine; Radionuclide Imaging; Scintillation Counting; Semiconductors; Sensitivity and Specificity; Tellurium; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Transducers; Zinc Compounds

The purpose of this study was to investigate if a novel parameter, the stress-to-rest ratio of the signal-to-noise ratio (RSNR) obtained with a cadmium zinc telluride (CZT) SPECT scanner, could be used to distinguish triple-vessel disease (TVD) patients.

Topics: Aged; Cadmium Compounds; Contrast Media; Coronary Angiography; Coronary Artery Disease; Exercise Test; Female; Humans; Male; Middle Aged; Signal-To-Noise Ratio; Single Photon Emission Computed Tomography Computed Tomography; Tellurium; Zinc Compounds

Gamma probes have been used for sentinel lymph node biopsy in melanoma and breast cancer. However, these probes can provide only radioactivity counts and variable pitch audio output based on the intensity of the detected radioactivity. We have developed a small semiconductor gamma camera (SSGC) that allows visualisation of the size, shape and location of the target tissues. This study is designed to characterise the performance of the SSGC for radioguided surgery of metastatic lesions and for other imaging applications amenable to the smaller format of this prototype imaging system. The detector head had 32 cadmium telluride semiconductor arrays with a total of 1,024 pixels, and with application-specific integrated circuits (ASICs) and a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mmx166 mmx65 mm. The effective visual field was 44.8 mmx44.8 mm. The energy resolution and imaging aspects were tested. Two spherical 5-mm- and 15-mm-diameter technetium-99m radioactive sources that had activities of 0.15 MBq and 100 MBq, respectively, were used to simulate a sentinel lymph node and an injection site. The relative detectability of these foci by the new detector and a conventional scintillation camera was studied. The prototype was also examined in a variety of clinical applications. Energy resolution [full-width at half-maximum (FWHM)] for a single element at the centre of the field of view was 4.2% at 140 keV (99mTc), and the mean energy resolution of the CdTe detector arrays was approximately 7.8%. The spatial resolution, represented by FWHM, had a mean value of 1.56 +/- 0.05 mm. Simulated node foci could be visualised clearly by the SSGC using a 15-s acquisition time. In preliminary clinical tests, the SSGC successfully imaged diseases in a variety of tissues, including salivary and thyroid glands, temporomandibular joints and sentinel lymph nodes. The SSGC has significant potential for diagnosing diseases and facilitating subsequent radioguided surgery.

Topics: Aged; Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Feasibility Studies; Female; Gamma Cameras; Humans; Lymph Nodes; Male; Neoplasms; Phantoms, Imaging; Pilot Projects; Reproducibility of Results; Sensitivity and Specificity; Sentinel Lymph Node Biopsy; Signal Processing, Computer-Assisted; Single-Blind Method; Surgery, Computer-Assisted; Tellurium; Tomography, Emission-Computed

Microelectrode-based photoelectrochemical (PEC) sensing is a newly developed and promising analytical technique for in vivo analysis. However, the inadequate specificity in complex environment of living bodies restricted its further in vivo application. Herein, we utilized a small molecule probe as the energy acceptor to quench the photocurrent of CdTe quantum dots through energy transfer. The efficiency of energy transfer was modulated by the concentration of target SO

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Gold; Limit of Detection; Metal Nanoparticles; Quantum Dots; Rats; Sulfur Dioxide; Tellurium

Quantum dots have been widely used for biomedical applications like imaging, targeted drug delivery, and

Topics: Cadmium; Cadmium Compounds; Feasibility Studies; Natriuretic Peptides; Quantum Dots; Tellurium

In this paper, a ternary-emission fluorescence imprinted polymer was one-pot synthesized by sol-gel method after mixing luminescence metal organic framework, green CdTe and near infrared red CdTe for visual detection of chloramphenicol in food. The ternary-emission fluorescence imprinted sensor showed wider linear range within concentration of 10 pM-0.5 nM and 0.5 nM-4.5 nM, with rapid response time of 3 min and the lower detection limit of 3.8 pM toward chloramphenicol. Meanwhile, NH

Topics: Cadmium Compounds; Chloramphenicol; Limit of Detection; Metal-Organic Frameworks; Molecular Imprinting; Polymers; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Multifunctional fluorescent probes have received increasing attention for the sake of atom economy and high-density integration. Herein, CdTe quantum dots (QDs) modified with Eu

Topics: Anthrax; Anti-Bacterial Agents; Biomarkers; Cadmium Compounds; Fluorescent Dyes; Humans; Quantum Dots; Spectrometry, Fluorescence; Spores; Tellurium; Tetracycline

Topics: Aminoglycosides; Anti-Bacterial Agents; Cadmium Compounds; Fluorescence; Fluorescent Dyes; Humans; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A photoelectrochemical (PEC) immunosensor based on MIL-101(Cr) and CdTe-QDs composites (M&C) was successfully synthesized to assay the carcinoembryonic antigen (CEA) in human serum and urine samples. This novel method contained three key aspects: 1), the polarity of the photocurrent based on MIL-101(Cr) itself could be altered by applying a different voltage to detect the cathode and anode photocurrent. 2), the introduction of cadmium telluride quantum dots (CdTe-QDs) greatly improved the efficiency of light utilization. 3), the photogenerated electron-hole-pairs were suppressed and their separation efficiency was improved by effective matching of energy level between MIL-101(Cr) and CdTe-QDs. Due to the inherent insulating properties of the biological matrix, the transfer of photogenerated electrons was hindered, leading to a decreased photocurrent signal. Under the optimal condition, the anodic and cathodic detection limit of the PEC immunosensor for CEA was 0.00018 ng mL

Topics: Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; Early Detection of Cancer; Humans; Immunoassay; Neoplasms; Quantum Dots; Tellurium

Since oxalate plays an important role in the metabolic assessment of urolithiasis, there is need for convenient and efficient methods for oxalate detection. Herein, we report a three-signal fluorescence strategy for oxalate analysis based on the ability of oxalate to reduce Cu

Topics: Cadmium Compounds; Costs and Cost Analysis; Fluorescence; Humans; Oxalates; Quantum Dots; Tellurium; Urolithiasis

Assessing the performance of spectroscopic x-ray detectors (SXDs) requires measurement of the frequency-dependent detective quantum efficiency (DQE). Analytical expressions of the task-based DQE and task-independent DQE of SXDs have been presented in the literature, but standardizable experimental methods for measuring them have not. The task-based DQE quantifies the efficiency with which an SXD uses the x-ray quanta incident upon it to either quantify or detect a basis material (e.g., soft tissue or bone) of interest. The task-independent DQE is akin to the conventional DQE in that it is independent of the basis material to be detected or quantified.. The purpose of this paper is to develop an experimental framework to present a method for experimental analysis of the DQE of SXDs, including the task-based DQE and task-independent DQE.. We develop methods to measure the frequency-dependent DQE for task of quantifying or detecting a perturbation in a known basis material. We also develop methods for measuring a task-independent DQE. We show that the task-based DQEs and the task-independent DQE can be measured using a modest extension of the methods prescribed by International Electrotechnical Commission (IEC). Specifically, measuring the task-independent DQE requires measuring the modulation transfer function (MTF) and noise power spectrum (NPS) of each energy-bin image, in addition to the cross NPS between energy-bin images. Measuring the task-based DQEs requires an additional measurement of the transmission fraction through a thin basis-material absorber. We implemented the developed methods using standardized IEC x-ray spectra, aluminum (Al) and polymethyl methacrylyte (PMMA) basis materials, and a cadmium telluride (CdTe) SXD equipped with two energy bins and analog charge summing (ACS) for charge-sharing suppression. We also performed a regression analysis to determine whether or not the task-independent DQE is predictive of the task-based DQEs.. Experimental results of the task-based DQEs were consistent with simulation results presented in the literature. In general, and as expected, ACS increased the task-based DQEs and task-independent DQE. This effect was most pronounced for quantification tasks, in some instances yielding a five-fold increase in the DQE. For both spectra, with and without ACS for charge sharing correction, the task-based DQEs were linearly related to the task-independent DQE, as demonstrated by R. We have extended experimental DQE analysis to SXDs that count photons in multiple energy bins in a single x-ray exposure. The developed framework is an extension of existing IEC methods, and provides a standardized approach to assessing the performance of SXDs.

Topics: Cadmium Compounds; Quantum Dots; Tellurium; X-Rays

Chemotherapy drugs of daunorubicin and doxorubicin treat cancers with many side effects. So, detection of them in the biological system for regulation and controlling of usage is essential. In this study, a ratiometric fluorescent method was introduced for detection of daunorubicin and doxorubicin using bell pepper-based carbon dots, as the variable signal, and silica-coated CdTe quantum dots, as the constant signal. The detection was done based on variations of carbon dots intensity in the presence of drugs in comparison with the constant intensity of silica-coated CdTe quantum dots. The proposed ratiometric fluorescent method was successfully used for detection of daunorubicin and doxorubicin range of 54.37-13594.34 nmolL

Topics: Anthraquinones; Cadmium Compounds; Carbon; Doxorubicin; Fluorescence; Fluorescent Dyes; Limit of Detection; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

Topics: Cadmium Compounds; Neural Networks, Computer; Quantum Dots; Semiconductors; Tellurium; Tomography, Emission-Computed, Single-Photon

A method for simultaneous labeling and multicolor fluorescence imaging of different hepatic immune cells below freezing point is established based on quantum dots. In the experiment, carbon quantum dots with emission wavelength of 435 nm, CdTe@CdS quantum dots at 542 nm and CdSe@ZnS quantum dots at 604 nm are synthesized respectively, it is found that when the mass fractions of KCl (as antifreeze) are 12 %, 14 %, and 12 %, respectively, the three quantum dot dispersion systems remain liquid state at -20 °C. After they are conjugated with the corresponding secondary antibodies, agarose gel electrophoresis, circular dichroism and capillary electrophoresis confirm the effectiveness of conjugation. By indirect immunofluorescence method, the above three quantum dot fluorescent probes are used to simultaneously and specifically target a variety of liver immune cells, and the multi-color simultaneous imaging of different liver immune cells is realized under the same excitation wavelength, it is found that hepatic macrophages are arranged radially in the liver, hepatic stellate cells present punctate distribution, and hepatic sinusoidal endothelial cells present circular distribution, which is consistent with the results of H&E staining and ultrathin section TEM. This study provides an important technical means for elucidating the structure and function of the liver.

Topics: Cadmium Compounds; Endothelial Cells; Freezing; Frozen Sections; Liver; Optical Imaging; Quantum Dots; Tellurium

While colloidal quantum dots (QDs) are commonly used as fluorescent donors within biosensors based on Förster resonant energy transfer (FRET), they are hesitantly employed as acceptors. On the sole basis of Förster theory and the well-known behaviour of organic dyes, it is often argued that the QD absorption band over the UV-visible range is too wide. Discarding these preconceptions inherited from classical fluorophores, we experimentally examine the FRET process occurring between donor and acceptor CdTe QDs and provide a mathematical description of it. We evidence that the specific features of QDs unexpectedly lead to the enhancement of acceptors' emission (up to +400%), and are thus suitable for the design of highly efficient all-QD based FRET sensors. Our model enables us to identify the critical parameters maximizing the contrast between positive and negative biosensing readouts: the concentrations of donors and acceptors, their spectral overlap, the densities of their excitonic states, their dissipative coupling with the medium and the statistics of QD-QD chemical pairing emerge as subtle and determinant parameters. We relate them quantitatively to the measured QD-QD FRET efficiency and discuss how they must be optimized for biosensing applications.

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescence Resonance Energy Transfer; Quantum Dots; Tellurium

Understanding the formation of protein corona (PC) is of vital importance for exploring the toxicity of nanoparticles and promoting their safe applications. In this study, CdTe QDs doping with 0, 1%, 5% and 10% Zn were synthesized using one-pot hydrothermal methods. Afterwards, this study explored and compared the formation of pure and Zn doped-QDs PC as well as the subsequent molecular and cellular toxicity. Result found that Zn doping regulated the toxicity of Cd-QDs by controlling their ability to adsorb serum proteins. The adsorption to Cd-QDs induced the dispersion, unfolding, secondary structural changes and the activity loss of bovine serum albumin (BSA). Among the synthesized Cd-QDs, 10%Zn-QDs exhibited the highest fluorescence quantum yield and lowest molecular toxicity. The formations of pure QDs and 10%Zn-QDs with BSA corona are majorly driven by different forces with different patterns. The regulation of BSA on the cytotoxicity differences of pure QDs and 10%Zn-QDs was similar with fetal bovine serum, proving the significant contribution of BSA to the cytotoxicity of Cd-QDs PC. Compared with pure QDs PC, the higher cytotoxicity and oxidative stress level of 10%Zn-QDs PC were correlated with higher intracellular [Cd

Topics: Cadmium; Cadmium Compounds; Protein Corona; Quantum Dots; Serum Albumin, Bovine; Tellurium; Zinc

It is significant for people with diabetes to know their body's real-time glucose level, which can guide the diagnosis and treatment. Therefore, it is necessary to research continuous glucose monitoring (CGM) as it gives us real-time information about our health condition and its dynamic changes. Here, we report a novel hydrogel optical fiber fluorescence sensor segmentally functionalized with fluorescein derivative and CdTe QDs/3-APBA, which can continuously monitor pH and glucose simultaneously. In the glucose detection section, the complexation of PBA and glucose will expand the local hydrogel and decrease the fluorescence of the quantum dots. The fluorescence can be transmitted to the detector by the hydrogel optical fiber in real time. As the complexation reaction and the swelling-deswelling of the hydrogel are all reversible, the dynamic change of glucose concentration can be monitored. For pH detection, the fluorescein attached to another segment of the hydrogel exhibits different protolytic forms when pH changes and the fluorescence changes correspondingly. The significance of pH detection is compensation for pH errors in glucose detection because the reaction between PBA and glucose is sensitive to pH. The emission peaks of the two detection units are 517 nm and 594 nm, respectively, so there is no signal interference between them. The sensor can continuously monitor glucose in 0-20 mM and pH in 5.4-7.8. The advantages of this sensor are multi-parameter simultaneous detection, transmission-detection integration, real-time dynamic detection, and good biocompatibility.

Topics: Blood Glucose; Blood Glucose Self-Monitoring; Cadmium Compounds; Fiber Optic Technology; Fluorescein; Glucose; Humans; Hydrogels; Hydrogen-Ion Concentration; Optical Fibers; Quantum Dots; Tellurium

Urolithiasis is a common disease with wide ranging effects, with oxalate stones being the most prevalent type. Existing clinical diagnostic methods rely on complex instruments and professionals, are difficult to distinguish between stone types, and have insufficient sensitivity. Moreover, high-sensitivity point-of-care testing (POCT) methods remain scarce. We constructed a rapid homogeneous dual fluorescence and binary visualization analysis system to diagnose oxalate urolithiasis because oxalate can efficiently reduce Cu

Topics: Cadmium Compounds; Calcium Oxalate; Humans; Oxalates; Quantum Dots; Tellurium; Urolithiasis

Copper (Cu

Topics: Cadmium Compounds; Copper; Fluorescent Dyes; Glutathione; Humans; Ions; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Topics: Cadmium Compounds; Colorimetry; Fluorescent Dyes; Humans; Mycophenolic Acid; Polyethyleneimine; Quantum Dots; Silicon Dioxide; Tellurium

A nanocomposite fluorescent probe was fabricated for the simultaneous determination of florfenicol and sparfloxacin based on fluorescence quenching. The probe was synthesized by integrating nitrogen-doped graphene quantum dots (N-GQDs), cadmium telluride quantum dots (CdTe QDs) and zinc oxide nanoparticles (ZnO) into a molecularly imprinted polymer (MIP). The determination was based on the quenching of fluorescence emissions from N-GQDs by florfenicol, detected at 410 nm, and the quenching of fluorescence emissions from CdTe QDs by sparfloxacin, detected at 550 nm. The fluorescent probe was highly sensitive and specific with good linear relationships for florfenicol and sparfloxacin in the range  0.10 to 100.0 μg L

Topics: Cadmium Compounds; Fluorescent Dyes; Polymers; Quantum Dots; Tellurium; Zinc Oxide

The rapid developments in nanotechnology have brought increased attention to the safety of Quantum Dots (QDs). Exploring their mechanisms of toxicity and characterizing their toxic effects in different cell lines will help us better understand and apply QDs appropriately. This study aims to elucidate the importance of reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress-induced autophagy for CdTe QDs toxicity, that is, the importance of the nanoparticles in mediating cellular uptake and consequent intracellular stress effects inside the cell. The results of the study showed that cancer cells and normal cells have different cell outcomes as a result of intracellular stress effects. In normal human liver cells (L02), CdTe QDs leads to ROS generation and prolong ER stress. The subsequent autophagosome accumulation eventually triggers apoptosis by activating proapoptotic signaling pathways and the expression of proapoptotic Bax. In contrast, in human liver cancer cells (HepG2 cells), expression of UPR restrains proapoptotic signaling and downregulates Bax, and activated protective cellular autophagy, as a result of protecting these liver cancer cells from CdTe QDs-induced apoptosis. In summary, we assess the safety of CdTe QDs and recounted the molecular mechanism underlying its nanotoxicity in normal and cancerous cells. Notwithstanding, additional detailed studies on the deleterious effects of these nanoparticles in the organisms of interest are required to ensure low-risk application.

Topics: Apoptosis; Autophagy; bcl-2-Associated X Protein; Cadmium Compounds; Cell Line; Endoplasmic Reticulum Stress; Humans; Liver Neoplasms; Quantum Dots; Reactive Oxygen Species; Tellurium

Accurate and in-time detection of bacteria conduces to preventing their rapid spread around the environment, while a nucleic acid test (NAT) is a powerful tool for early diagnosis of pathogens. Herein, we propose a hybridization chain reaction (HCR)-mediated multisite exonuclease III (Exo-III) amplification strategy (HCR/Exo-III amplifier) to achieve the one-pot and ultrasensitive isothermal amplification of bacterial 16S rRNA and a portable fluorescence detection device (PFD) to directly read signals in a lateral flow assay (LFA). In detail, the target-initiated HCR products present multiple binding sites for triggering the Exo-III amplifier that produces numerous target amplicons. Following that, the target amplicons travel up on the strip and bridge between the DNA-CdTe/CdS probes and the capture DNA to form a positive fluorescence line. After that, the strip is inserted into the PFD to accomplish the fluorescence signal reading. The constructed HCR/Exo-III amplifier-based PFD-LFA implemented the simultaneous and specific detection of three bacteria with a detection limit of a few tenths of fM for synthetic 16S rRNA fragments and dozens of CFU/mL for

Topics: Biosensing Techniques; Cadmium Compounds; DNA; DNA Probes; Exodeoxyribonucleases; Limit of Detection; Nucleic Acid Amplification Techniques; Nucleic Acid Hybridization; Quantum Dots; RNA, Ribosomal, 16S; Tellurium

Topics: Animals; Bismuth; Cadmium Compounds; Contrast Media; Iodine; Mice; Quantum Dots; Tellurium; X-Ray Microtomography

We applied transient absorption spectroscopy to study the early photodynamics in a system composed of CdTe quantum dots (QDs) and cytochrome c (Cyt c) protein. In the QDs and Cyt c mixtures, about 25 % of the excited QD electrons quickly relax (∼23 ps) to the ground state and roughly 75 % decay on slower time scale - mostly due to quenching by Cyt c. On the basis of the assumed model, we estimated the contribution of electron transfer and other mechanisms to this quenching. The primary quenching mechanism is probably energy transfer but electron transfer makes a significant contribution (∼8 %), resulting in photoreduction of Cyt c. The lifetime of one fraction of reduced Cyt c (35-90 %) is ∼ 1 ms and the lifetime of the remaining fraction was longer than the ∼ 50-ms time window of the experiment. We speculate that, in the former fraction, the back electron transfer from the reduced Cyt c to QDs occurs and the latter fraction of Cyt c is stably reduced.

Topics: Cadmium Compounds; Cytochromes c; Electrons; Quantum Dots; Tellurium

The Eiger 2X CdTe 1 M-W (Dectris ltd, Baden, Switzerland) single photon counting detector was characterized for imaging applications at the biomedical beamline ID17 of the European Synchrotron Radiation Facility.. Linearity, Modulation Transfer Function, Noise Power Spectrum and Detective Quantum Efficiency were measured as a function of photon energy and flux in the range 26-80 keV.. The linearity was confirmed in the flux range specified by Dectris and a detection efficiency higher than 60 % was measured for energies up to 80 keV. The spatial resolution was inferred from the Modulation Transfer Function and was found to be compatible with the pixel size of the detector (75 μm), except at energies just above the K-edge of Cd and Te where it reached 150 μm. The study of the Noise Power Spectrum showed a time-dependency in the response of the sensor, which is mitigated at low photon fluxes (<2⨯10. This work was the first characterization of the Eiger 2X CdTe 1 M-W for imaging applications with monochromatic synchrotron radiation. The spatial resolution and the quantum efficiency are compatible with low-dose imaging applications.

Topics: Cadmium Compounds; Photons; Quantum Dots; Tellurium

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Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; gamma-Cyclodextrins; Humans; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Immunoassay; Limit of Detection; Luminescent Measurements; Quantum Dots; Tellurium

Alzheimer's disease (AD) is characterized by a distinct pattern of cortical thinning and resultant changes in cognition and function. These result in prominent deficits in cognitive-motor automaticity. The relationship between AD-related cortical thinning and decreased automaticity is not well-understood. We aimed to investigate the relationship between cortical thickness regions-of-interest (ROI) and automaticity and attention allocation in AD using hypothesis-driven and exploratory approaches. We performed an ROI analysis of 46 patients with AD. Data regarding MR images, demographic characteristics, cognitive-motor dual task performance, and cognition were extracted from medical records. Cortical thickness was calculated from MR T1 images using FreeSurfer. Data from the dual task assessment was used to calculate the combined dual task effect (cDTE), a measure of cognitive-motor automaticity, and the modified attention allocation index (mAAI). Four hierarchical multiple linear regression models were conducted regressing cDTE and mAAI separately on (1) hypothesis-generated ROIs and (2) exploratory ROIs. For cDTE, cortical thicknesses explained 20.5% (p = 0.014) and 25.9% (p = 0.002) variability in automaticity in the hypothesized ROI and exploratory models, respectively. The dorsal lateral prefrontal cortex (DLPFC) (β =  - 0.479, p = 0.018) and superior parietal cortex (SPC) (β = 0.467, p = 0.003), and were predictors of automaticity. For mAAI, cortical thicknesses explained 20.7% (p = 0.025) and 28.3% (p = 0.003) variability in attention allocation in the hypothesized ROI and exploratory models, respectively. Thinning of SPC and fusiform gyrus were associated with motor prioritization (β =  - 0.405, p = 0.013 and β =  - 0.632, p = 0.004, respectively), whereas thinning of the DLPFC was associated with cognitive prioritization (β = 0.523, p = 0.022). Cortical thinning in AD was related to cognitive-motor automaticity and task prioritization, particularly in the DLPFC and SPC. This suggests that these regions may play a primary role in automaticity and attentional strategy during dual-tasking.

Topics: Alzheimer Disease; Attention; Cadmium Compounds; Cerebral Cortex; Cerebral Cortical Thinning; Cognition; Humans; Magnetic Resonance Imaging; Quantum Dots; Tellurium

Aiming for precise, real-time, and on-site analysis of proteins, an innovative binary-emission fluorescence imprinted polymer was designed by sol-gel method after mixing MIL-101(Cr), green CdTe (g-CdTe) and red CdTe (r-CdTe) for detection of protein. In this proposal, MIL-101(Cr), as a favorable supporter, provided high surface area and porosity for imprinting sites, which ameliorated the transfer rate and the sensitivity of the nanosensor. And g-CdTe and r-CdTe were served as signal transduction for dual-emission response. Based on strengthened recognition reaction between high-affinity imprinting sites and protein, the fluorescence intensities of g-CdTe and r-CdTe yielded conspicuous two responses at 528 nm and 634 nm for protein under the excitation of 350 nm. The cytochrome c (Cyt c) and trypsin were served as model proteins to verify the generality of strategy. Given prominent merits of MIL-101(Cr), g-CdTe/r-CdTe@MIL-101(Cr)@MIP exhibited good linear range of 1-30 μM for Cyt c and 0.15-4 μM for trypsin, and the limit of detection were 0.13 μM and 0.014 μM, respectively. Significantly, an unsophisticated smartphone-based sensing device was developed by integrating g-CdTe/r-CdTe@MIL-101(Cr)@MIP with a 3D printing portable device to obtain precise on-site results. As expected, this portable platform was successfully applied for monitoring Cyt c and trypsin with a detection limit of 0.71 μM and 0.026 μM, respectively. These results indicated this dual-response molecularly imprinted fluorescence senor based on smartphone provided promising perspectives on futural on-site protein analysis.

Topics: Cadmium Compounds; Limit of Detection; Molecular Imprinting; Quantum Dots; Smartphone; Tellurium; Trypsin

Topics: Anti-Bacterial Agents; Cadmium Compounds; Carbon; Fluorescent Dyes; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Tetracyclines

Excessive consumption of Δ9-tetrahydrocannabinol (THC) severely endangers human health and has raised public safety concerns. However, its quantification by readily rapid tools with simplicity and low cost is still challenging. Herein, we found that a G-rich THC aptamer (THC1.2) can tightly bind to thioflavin T (ThT) with strong fluorescence, which would be specifically quenched in the presence of THC. Based on that, a label-free ratiometric fluorescent sensor for the sensing of THC and its metabolite (THC-COOH) based on THC1.2/ThT as a color emitter and red CdTe quantum dots as reference fluorescence was constructed. Notably, a transition of the fluorescent color of the ratiometric probe from green to red can be instantly observed upon the increased concentration of THC and THC-COOH. Furthermore, a portable smartphone-based fluorescence device integrated with a self-programmed Python program was fabricated and used to accomplish on-site monitoring of THC and THC-COOH within 5 min. Under optimized conditions, this ratiometric fluorescent sensor allowed for an instant response toward THC and its metabolite with considerable limits of detection of 97 and 254 nM, respectively. The established sensor has been successfully applied to urine and saliva samples and exhibited satisfactory recoveries (88-116%). This ratiometric fluorescent sensor can be used for the simultaneous detection of THC and THC-COOH with the advantages of rapidness, low cost, ease of operation, and portability, providing a promising strategy for on-site detection and facilitating law enforcement regulation and roadside control of THC.

Topics: Cadmium Compounds; Coloring Agents; Dronabinol; Fluorescent Dyes; Gas Chromatography-Mass Spectrometry; Humans; Limit of Detection; Quantum Dots; Smartphone; Tellurium

Herein, we report a fluorescence strategy for the homogeneous and simultaneous analysis of urine miRNA-375 and miRNA-148a. The target miRNAs in urine bonded the devised dumbbell-shaped "C-Ag

Topics: Biomarkers, Tumor; Cadmium Compounds; Humans; Male; MicroRNAs; Prostate-Specific Antigen; Prostatic Neoplasms; Quantum Dots; Tellurium

Antibiotic residues pose a serious threat to ecosystems and food safety. Developing convenient, visual, and on-site detection methods is therefore in high demand and has a practical purpose. In this work, a near-infrared (NIR) fluorescent probe with an analysis platform based on a smartphone has been constructed for quantitative and on-site detection of metronidazole (MNZ). CdTe quantum dots with NIR emission at 710 nm (QD710) were prepared by using a simple hydrothermal method and showed good properties. A spectral overlap between absorption of MNZ and excitation of QD710 resulted in an effective inner filter effect (IFE) between QD710 and MNZ. Because of the IFE, the fluorescence of QD710 decreased gradually with increasing concentrations of MNZ. Based on the fluorescence response, quantitative detection and visualization of MNZ was achieved. NIR fluorescence analysis and the special IFE between probe and target can improve sensitivity and selectivity for MNZ. Additionally, these were also utilized for quantitative detection of MNZ in real food samples and the results were reliable and satisfactory. Meanwhile, a portable visual analysis platform in a smartphone was constructed for on-site analysis of MNZ, which can be used as an alternative method for detection of MNZ residues in situations with limited instrumental conditions. Therefore, this work provides a convenient, visual, and real-time analysis method for detection of MNZ and the analysis platform shows great potential for commercialization.

Topics: Cadmium Compounds; Carbon; Ecosystem; Fluorescent Dyes; Limit of Detection; Metronidazole; Quantum Dots; Smartphone; Tellurium

Topics: Aspirin; Cadmium Compounds; Chemometrics; Quantum Dots; Tellurium

Bacillus anthracis spores can make humans infected with vicious anthrax, so it is significant to detect their biomarker 2,6-pyridinedicarboxylic acid (DPA). The development of dual-modal methods for DPA detection that are more flexible in practical applications remains a challenge. Herein, colorimetric xylenol orange (XO) was modified on fluorescent CdTe quantum dots (QDs) for dual-modal detection of DPA through competitive coordination. After the binding of XO on CdTe QDs via coordination with Cd

Topics: Anthrax; Biomarkers; Cadmium; Cadmium Compounds; Colorimetry; Fluorescent Dyes; Humans; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Developing hollow-structure quantum dot carriers to increase quantum luminous efficiency is a creative idea for designing a novel sensor. A ratiometric hollow CdTe@H-ZIF-8/CDs@MIPs sensor was developed for the sensitive and selective detection of dopamine (DA). CdTe QDs and CDs were used as the reference signal and recognition signal, respectively, and thus showed a visual effect. MIPs provided high selectivity toward DA. The TEM image demonstrated that the sensor was a hollow structure, which could have ample opportunity to excite quantum dots to emit light through multiple light scattering through holes. In the presence of DA, the fluorescence intensity of the optimum CdTe@H-ZIF-8/CDs@MIPs was remarkably quenched by DA, achieving a linear range of 0-600 nM and a limit of detection of 12.35 nM. The developed ratiometric fluorescence sensor showed an obvious and meaningful color change with a gradual increase in DA concentration under a UV lamp. Moreover, the optimum CdTe@H-ZIF-8/CDs@MIPs was remarkably sensitive and selective in detecting DA among various analogs and showed good anti-interference ability. The HPLC method also further confirmed that CdTe@H-ZIF-8/CDs@MIPs shows good practical application prospects.

Topics: Cadmium Compounds; Dopamine; Fluorescent Dyes; Limit of Detection; Molecular Imprinting; Quantum Dots; Spectrometry, Fluorescence; Tellurium

With the goal to investigate biological phenomena at a single-cell level, we designed, synthesized and tested a molecular probe based on Förster resonance energy transfer (FRET) between a highly luminescent quantum dot (QD) as a donor and a fluorophore or fluorescence quencher as an acceptor linked by a specific peptide. In principle, QD luminescence, effectively dissipated in the probe, is switched on after the cleavage of the peptide by a protease and the release of the quencher. We proposed a novel synthesis strategy of a probe. A two-step synthesis consists of: (i) Conjugation of CdTe QDs functionalized by -COOH groups of succinic acid on the nanoparticle surface with the designed specific peptide (GTADVEDTSC) using a ligand-exchange approach; (ii) A fast, high-yield reaction of amine-reactive succinimidyl group on the BHQ-2 quencher with N-terminal of the peptide. This way, any crosslinking between individual nanoparticles and any nonspecific conjugation bonds are excluded. The analysis of the product after the first step proved a high reaction yield and nearly no occurrence of unreacted QDs, a prerequisite of the specificity of our luminescent probe. Its parameters evaluated as Michaelis-Menten description of enzymatic kinetics are similar to products published by other groups. Our research is focused on the fluorescence microscopy analyses of biologically active molecules, such as proteolytic active caspases, playing important roles in cell signaling regulations in normal and diseased states. Consequently, they are attractive targets for clinical diagnosis and medical therapy. The ultimate goal of our work was to synthesize a new QD luminescent probe for a long-time quantitative monitoring of active caspase-3/7 distribution in apoptotic osteoblastic MC3T3-E1 cells treated with camptothecin. As a result of comparison, our synthetized luminescent probe provides longer imaging times of caspases than commercial products. The probe proved the stability of the luminescence signal inside cells for more than 14 days.

Topics: Cadmium Compounds; Caspases; Fluorescence Resonance Energy Transfer; Peptide Hydrolases; Peptides; Quantum Dots; Tellurium

Multiplexed gene assay for simultaneously detecting the multi-targets of nucleic acids is strongly anticipated for the accurate diseases diagnosis and prediction, and all commercial available gene assays for IVD are a kind of single-target assay. Herein, a dual-potential encoded and coreactant-free electrochemiluminescence (ECL) strategy is proposed for the multiplexed gene assay, which can be conveniently carried out by directly oxidizing the same luminescent tag of dual-stabilizers-capped CdTe nanocrystals (NCs). The CdTe NCs linked with sulfhydryl-RNA via Cd-S bond merely exhibits one ECL process around 0.32 V with a narrow triggering-potential-window of 0.35 V, while CdTe NCs linked with amino-RNA via amide linkage solely gives off one ECL process around 0.82 V with a narrow triggering-potential-window of 0.30 V. Multiplexing ECL of both sulfhydryl-RNA-functionalized CdTe NCs and amino-RNA-functionalized CdTe NCs can be utilized to simultaneously detect the open reading frame 1ab (ORF1ab) and the nucleoprotein (N) genes without crosstalk, in which ECL of sulfhydryl-RNA-functionalized CdTe NCs can dynamically determine ORF1ab from 200 aM to 10 fM with a limit of detection (LOD) of 100 aM, while ECL of amino-RNA-functionalized CdTe NCs can linearly detect N gene from 5 fM to 1 pM with a LOD of 2 fM. Post-engineering CdTe NCs with RNA in a labeling-bond engineering way would provide a potential-selective and encoded ECL strategy for multiplexed gene assay with one luminophore.

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Limit of Detection; Luminescent Measurements; Quantum Dots; RNA; Tellurium

In this paper, glutathione (GSH)-coated Zn-doped CdTe quantum dots (QDs) with different particle sizes were synthesized using the "reflow method", and the interaction mechanism between the two QDs and lactoferrin (LF) was investigated systemically with different spectroscopic methods. The steady-state fluorescence spectra showed that the LF formed a tight complex with the two QDs through static bursting and that the electrostatic force was the main driving force between the two LF-QDs systems. The complex generation process was found to be spontaneous (ΔG < 0) and accompanied by exothermic and increasing degrees of freedom (ΔH < 0, ΔS > 0) by using the temperature-dependent fluorescence spectroscopy. The critical transfer distance (R

Topics: Cadmium Compounds; Lactoferrin; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Zinc

Topics: Cadmium Compounds; Phantoms, Imaging; Photons; Quantum Dots; Radiography; Tellurium

In this work, a potential-resolved electrochemiluminescence (ECL) multiplex immunoassay (MIA) was developed using zirconium-based metal-organic framework (MOF) nanoparticles with intense self-ECL as an anodic ECL tag and CdTe nanocrystals (NCs) as a cathodic ECL tag. ECL luminophore 5,5'-(anthracene-9,10-diyl)diisophthalic acid (H

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Immunoassay; Limit of Detection; Luminescent Measurements; Metal Nanoparticles; Metal-Organic Frameworks; Nanoparticles; Quantum Dots; Tellurium; Zirconium

Lipopolysaccharide (LPS) as the component of cell membrane on gram-negative bacteria played a central role on inflammatory inducer to stimulate a multi-system host response. Herein, a surface-enhanced fluorescent (SEF) sensor was developed for LPS analysis based on shell-isolated nanoparticles (SHINs). The fluorescent signal of CdTe quantum dots (QDs) was amplified by silica shell-coated Au nanoparticles (Au NPs). The 3D finite-difference time-domain (3D-FDTD) simulation revealed that this enhancement was due to local electric field amplification. This method has a linear detection range of 0.1-20 μg/mL and a detection limit of 64 ng/mL for LPS. Furthermore, the developed method was successfully applied for LPS analysis in milk and human serum sample. The results indicated that the as-prepared sensor has significant potential for selective detection of LPS in biomedical diagnosis and food safety.

Topics: Cadmium Compounds; Coloring Agents; Fluorescence; Gold; Humans; Lipopolysaccharides; Metal Nanoparticles; Quantum Dots; Tellurium

Topics: Cadmium Compounds; Photons; Quantum Dots; Tellurium

A molecularly imprinted polymers (MIPs)-isolated AuNP-enhanced fluorescence sensor, AuNP@MIPs-CdTe QDs, was developed for highly sensitive and selective detection of oxytetracycline (OTC) in aqueous medium. The developed sensor combined the advantages of strong fluorescence signal of metal-enhanced fluorescence (MEF), high selectivity of MIPs, and stability of CdTe QDs. The MIPs shell with specific recognition served as an isolation layer to adjust the distance between AuNP and CdTe QDs to optimize the MEF system. The sensor demonstrated the detection limit as low as 5.22 nM (2.40 μg/L) for a concentration range of 0.1-3.0 μM OTC and good recovery rates of 96.0-103.0% in real water samples. In addition, high specificity recognition for OTC over its analogs was achieved with an imprinting factor of 6.10. Molecular dynamics (MD) simulation was utilized to simulate the polymerization process of MIPs and revealed H-bond formation as the mainly binding sites of APTES and OTC, and finite-difference time-domain (FDTD) analysis was employed to obtain the distribution of electromagnetic field (EM) for AuNP@MIPs-CdTe QDs. The experimental results combined with theoretical analyses not only provided a novel MIP-isolated MEF sensor with excellent detection performance for OTC but also established a theoretical basis for the development of a new generation of sensors.

Topics: Cadmium Compounds; Limit of Detection; Molecular Imprinting; Molecularly Imprinted Polymers; Oxytetracycline; Quantum Dots; Tellurium; Water

The fundamental properties of dislocations in diamond-structured Si and sphalerite-structured GaAs, InP and CdTe are investigated based on lattice theory of dislocation, hoping to provide some theoretical references in improving the properties of related materials. The influences of the surface effect(SE) and elastic strain energy on the structure and mechanical property of dislocation are discussed systematically. After considering the SE, the core width of dislocation becomes wider due to the elastic interaction between atoms becomes stronger. Compared to glide partial dislocation, the correction of SE to shuffle dislocation is more obvious. Both the SE and the elastic strain energy affect the energy barrier and Peierls stress of dislocation. The influence of SE on energy barrier and Peierls stress mainly results from the misfit energy and elastic strain energy become lower when the core of dislocation becomes wider. While the influence of elastic strain energy on energy barrier and Peierls stress mainly results from the cancellation between misfit energy and elastic strain energy for they possess comparable amplitudes but opposite phases. In addition, it is deduced that for the studied crystals, the shuffle dislocations control the deformation at medium and low temperatures, while glide partial dislocations are responsible for high temperature plasticity.

Topics: Cadmium Compounds; Diamond; Humans; Joint Dislocations; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; Carbon; DNA; Electrochemical Techniques; Humans; Immunoglobulin G; Quantum Dots; Tellurium

As a tumor biomarker, the accumulation of amyloid β oligomers (Aβo) in the brain has been suggested as a key feature in the pathogenesis and progression of Alzheimer's disease (AD). In this work, we designed a novel photoelectrochemical (PEC) and electrochemiluminescence resonance energy transfer (ECL-RET) dual-mode biosensor to achieve ultra-sensitive detection of Aβo. Specifically, the electrode surface modified Carbon Dots (C Dots) and the electrodeposited polyaniline (PANI) film formed a Z-scheme heterojunction reversing the photocurrent signal, and then the Aβo specific recognition peptide was attached to the surface via amide bonding between the amino group of PANI and carbonyl group of peptide. After that, in the presence of CdTe labeled specific recognition aptamer for Aβ (CdTe-Apt), Aβo was captured to construct a sandwich-type biosensor and exhibited a significantly enhanced cathodic photocurrent response because the formed dual Z-scheme heterojunction promoted charge separation efficiency. Interestingly, the proposed biosensor also caused a ratiometric change in the ECL intensity at 555 nm and 640 nm. Therefore, the developed biosensor achieved dual-mode detection of Aβo, where the PEC detection range of Aβo was from 10 fM to 0.1 μM (with a detection limit of 4.27 fM) and the ECL method provided a linear detection range of 10 fM to 10 nM (with a detection limit of 6.41 fM). The stability and reliability of the experimental results indicate that this has been a promising biosensing pattern and could be extended to the analysis of other biomarkers.

Topics: Amyloid beta-Peptides; Biomarkers, Tumor; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Limit of Detection; Quantum Dots; Reproducibility of Results; Tellurium

The estimation of the characteristic parameters of the electrical contacts in CdZnTe and CdTe detectors is related to the identification of the main transport mechanisms dominating the currents. These investigations are typically approached by modelling the current-voltage

Topics: Cadmium Compounds; Quantum Dots; Tellurium

Quinolone antibiotics (norfloxacin) pose a serious threat to animal and human health due to their misuse and difficulty in being broken down in surface water and food. Rapid and effective detection of norfloxacin (NOR) is essential for environmental testing and ecosystems. In this study, yttrium was coordinated with mercaptopropionic acid (MPA)-modified CdTe quantum dots (QDs) to obtain a novel fluorescence sensor Y

Topics: Animals; Cadmium Compounds; Ecosystem; Fluorescence; Fluorescent Dyes; Humans; Norfloxacin; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

A photoelectrochemical (PEC) detection platform was built based on the branched rutile/anatase titanium dioxide (RA-TiO

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Electrodes; Electrons; Limit of Detection; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; DNA, Single-Stranded; Fluorescence; HIV; HIV Infections; Humans; Limit of Detection; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Ion Exchange; Limit of Detection; Luminescent Measurements; Quantum Dots; Tellurium; Thrombin

High tube current generates a high flux of x-rays to photon counting detectors (PCDs) that can potentially result in the piling up of pulses formed by concurrent photons, which can cause count loss and energy resolution degradation.. To evaluate the performance of clinical photon-counting CT (PCCT) systems in high flux, potentially influenced by pulse pileup effects, in terms of task-generic image quality metrics.. A clinical phantom was scanned on a commercial PCCT scanner (NAEOTOM Alpha, Siemens) at 120 kV under fourteen different tube current levels (40-1000 mA) with a rotation time of 0.25 s and a pitch of 1. The dose levels corresponded to CTDI. The 50% cut-off frequency of TTF (f. Increasing tube currents did not affect the spatial resolution, but slightly affected the CT number and noise measurements of the clinical PCCT system. However, the effects were only considerable at clinically irrelevant tube currents used on a small 20-cm phantom. In general clinical practices, automatic exposure control techniques are used to decrease the variation of flux on the detector, which alleviates the chances of detector saturation due to high count rates. The observed effects could be due to pulse pileup, signal-dependent filtration of the system, or nonlinearities in the reconstruction algorithm. In conclusion, either the deadtime of the detector used in the photon-counting CT system is shorter such that count losses due to pulse pileup are negligible, or pulse pileup has inconsiderable effects on the image quality of clinical photon-counting CT systems in routine clinical practice due to possible corrections applied on the system.

Topics: Cadmium Compounds; Phantoms, Imaging; Photons; Quantum Dots; Tellurium; Tomography, X-Ray Computed

A self-assembled fluorescent nanosensor for the determination of L-cysteine (Cys) was constructed based on the mechanism of fluorescence resonance energy transfer (FRET). In this system, CdTe/ZnS QDs serve as the energy donor while AuNPs serve as the receptor, resulting in the occurrence of FRET with dramatic fluorescence quenching of the QDs (turn off). Once Cys is added, AuNPs can adsorb Cys, leading to the release of the QDs. The process would inhibit the FRET, which contributed to the recovery of fluorescence (turn on) and an off-on fluorescence aptasensor for Cys detection was constructed accordingly. The linear response range of the fluorescence sensor is from 0.8 to 50 μM, and the detection limit is 0.24 μM. The sensor demonstrates great sensitivity and selectivity to Cys. More importantly, the QD-based sensing platform was successfully used for the detection of Cys in milk samples with high precision and accuracy, indicating the potential of the probe in practical applications.

Topics: Cadmium Compounds; Coloring Agents; Cysteine; Fluorescence Resonance Energy Transfer; Gold; Metal Nanoparticles; Quantum Dots; Tellurium

Topics: Cadmium Compounds; DNA, Catalytic; Quantum Dots; Tellurium

As an estrogenic mycotoxin found in a wide range of agricultural crops, the toxicity of zearalenone (ZEN) poses a serious risk to human health. Accordingly, to achieve rapid detection of zearalenone in complex samples, an aptamer fluorescence sensor based on magnetic graphene oxide was developed. Compared with traditional methods, this technique has the virtues of simple operation, low cost, and reliable performance. Magnetic graphene oxide (MGO) was synthesized as a fluorescent bursting agent, using a chemical precipitation approach by depositing Fe

Topics: Aptamers, Nucleotide; Cadmium Compounds; Fluorescent Dyes; Humans; Limit of Detection; Magnesium Oxide; Magnetic Phenomena; Mycotoxins; Quantum Dots; Tellurium; Zearalenone

This work reports the development and application of a highly selective core@shell-based quantum dot-molecularly imprinted polymer (QD@MIP) sensor for the detection of sulfadiazine (SDZ)-an antibiotic which belongs to the sulfonamide family. The synthesis of the smart material or MIP (molecularly imprinted polymer) was carried out by a precipitation method directly on the quantum dot surface, which played the role of a fluorescent probe in the optical sensor. The synthesized polymer was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Fluorescence experiments were performed in order to evaluate the effects of pH, interaction time of the QD@MIP with the analyte and SDZ concentration in different matrices. Under optimized conditions, a linear concentration range of 10.0-60.0 ppm and a limit of detection of 3.33 ppm were obtained. The repeatability and reproducibility of the proposed QD@MIP were evaluated in terms of the RSD, where RSD values of less than 5% were obtained in both tests. Selectivity studies were carried out in the presence of four possible interfering substances with quenching properties, and the signals obtained for these interferents confirmed the excellent selectivity of the proposed sensor; the imprinting factor value obtained for SDZ was 1.64. Finally, the proposed sensor was applied in real animal-based food samples using a spiked concentration of SDZ, where the recovery values obtained were above 90% (experiments were performed in triplicate).

Topics: Animals; Anti-Bacterial Agents; Cadmium Compounds; Limit of Detection; Molecular Imprinting; Molecularly Imprinted Polymers; Quantum Dots; Reproducibility of Results; Sulfadiazine; Sulfanilamide; Tellurium

MicroRNAs (miRNAs) hold potential as useful biomarkers for early diagnosis and evaluation of diverse cancers, but their low abundance and short length make the detection of miRNAs face low sensitivity and accuracy. Herein, a photoluminescence (PL)-resonance light scattering (RLS) dual-mode method was developed for the sensitive and accurate detection of miRNA-141 using CdTe quantum dots (QDs) and Au nanoparticles. The presence of miRNA-141 induced PL quenching and RLS increasing. The limit of detection (LOD) was as low as 3.7 fM, and the miRNA-141 was detected linearly in a range from 10 fM to 10 nM. The dual signals generated no mutual interference and were detected using the same spectrophotometer, allowing for mutual validation to ensure the accuracy and reliability of the detection results. This study proposes valuable references for constructing dual-mode detection methods.

Topics: Biosensing Techniques; Cadmium Compounds; Gold; Limit of Detection; Metal Nanoparticles; MicroRNAs; Quantum Dots; Reproducibility of Results; Tellurium

Programmable artificial photosynthetic cell is the ultimate goal for mimicking natural photosynthesis, offering tunable product selectivity via reductase selection toward device integration. However, this concept is limited by the capacity of regenerating the multiple cofactors that hold the key to various reductases. Here, we report the design of artificial photosynthetic cells using biotic-abiotic thylakoid-CdTe as hybrid energy modules. The rational integration of thylakoid with CdTe quantum dots substantially enhances the regeneration of bioactive NADPH, NADH and ATP cofactors without external supplements by promoting proton-coupled electron transfer. Particularly, this approach turns thylakoid highly active for NADH regeneration, providing a more versatile platform for programming artificial photosynthetic cells. Such artificial photosynthetic cells can be programmed by coupling with diverse reductases, such as formate dehydrogenase and remodeled nitrogenase for highly selective production of formate or methane, respectively. This work opens an avenue for customizing artificial photosynthetic cells toward multifarious demands for CO

Topics: Cadmium Compounds; Carbon Dioxide; NAD; Nitrogenase; Photosynthesis; Quantum Dots; Tellurium

RGO-CdTe composite was synthesized using a straightforward, easy-to-realize, one-pot solvothermal technique. The synthesized composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), Raman spectra, UV-Vis absorption, and photoluminescence measurement. The RGO-CdTe composite exhibited 83.6% photocatalytic degradation efficiency for the aqueous tetracycline (TC) antibiotic solution and the apparent quantum yield (AQY) for the same was as high as 22.29% which is 2.63 times higher than that of CdTe. The scavenger investigation demonstrated that although hole acts as the leading active species, despite that, superoxide and hydroxyl radicals have also played crucial roles. The initial pH-dependent photocatalytic performance was measured. The zeta potential of the composite at different pH values was evaluated to establish the photocatalytic performance of the RGO-CdTe towards TC degradation at different pH. The recycling experiment depicts that only a 10% degradation performance declines after 5 times recycle use of the RGO-CdTe photocatalyst. An efficient photocurrent generation in RGO-CdTe thin film device has also been observed. Our study establishes as-synthesized composite of RGO-CdTe as a highly potential, and stable photocatalyst for the degradation of antibiotics from the polluted aqueous environment with a very good photoinduced charge generation efficiency in its solid phase.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Heterocyclic Compounds; Quantum Dots; Tellurium; Tetracycline; Tetracyclines

Multi-radionuclide in vivo imaging with submillimetre resolution can be a potent tool for biomedical research. While high-resolution radionuclide imaging faces challenges in sensitivity, multi-radionuclide imaging encounters difficulty due to radiation contamination, stemming from crosstalk between radionuclides and Compton scattering. Addressing these challenges simultaneously is imperative for multi-radionuclide high-resolution imaging. To tackle this, we developed a high-spatial-resolution and high-energy-resolution small animal single-photon emission computed tomography (SPECT) scanner, named CdTe-DSD SPECT-I. We first assessed the feasibility of multi-tracer SPECT imaging of submillimetre targets. Using the CdTe-DSD SPECT-I, we performed SPECT imaging of submillimetre zeolite spheres absorbed with

Topics: Animals; Cadmium Compounds; Iodine Radioisotopes; Lymphatic Metastasis; Mice; Phantoms, Imaging; Quantum Dots; Tellurium; Tomography, Emission-Computed, Single-Photon

Tellurium is massively used as the main light-absorbing layer component in the manufacturing of CdTe thin-film solar cells, a critical component in the photovoltaic industry. However, the process of manufacturing and renewing components has produced large amounts of tellurium-containing wastewater that is difficult to degrade and poses a serious threat to the aquatic ecosystem and human health. Hence, to achieve the recovery of tellurium resources for reducing their damages, a win-win approach was employed to utilize waste lignin to construct functional copper-doped activated lignin (CAL) adsorbents for selective separation and recovery of tellurium from wastewater. CAL exhibited superior adsorption properties towards tellurium (248.45 mg/g), mainly attributed to the adsorption mechanism of coordination interactions. Kinetic and isotherm results elucidated that monolayer chemisorption dominated CAL adsorption process. Besides, CAL had a satisfactory regeneration capability with minimal loss adsorption capacity after six consecutive cycles, which also exhibited high antifouling properties. Meanwhile, CAL achieved high selectivity for tellurium adsorption under the simulated wastewater, revealing the potential of CAL for practical application in wastewater. Therefore, this work provides a promising environmental strategy for exploring the application of lignin-based materials for tellurium recovery from wastewater.

Topics: Adsorption; Cadmium Compounds; Ecosystem; Humans; Kinetics; Lignin; Quantum Dots; Tellurium; Wastewater; Water Pollutants, Chemical

A hybrid fluorescent sensing probe was developed and used to quantitatively analyse thiamphenicol. The probe was constructed by entrapping mesoporous carbon and CdTe*CdS*ZnS quantum dots in molecularly imprinted polymer. The probe was characterized, and the construction and detection conditions were optimized. In the optimized conditions, the recognition sites of the nanoprobe were ultrasensitive and highly selective toward thiamphenicol. The quantitative analysis of thiamphenicol was based on the fluorescence quenching of the hybrid nanoprobe by thiamphenicol. Fluorescence emission was quenched linearly from 0.10 to 100 μg L

Topics: Animals; Cadmium Compounds; Carbon; Limit of Detection; Milk; Molecular Imprinting; Polymers; Quantum Dots; Tellurium; Thiamphenicol

The pressing need to develop a specific analytical sensor that can identify and quantify Fe(II) without a cytotoxic response was the major motivation drive in this work. The turn-on fluorescent sensor here described can successfully detect Fe(II) and discriminate this ion from other analytes that commonly act as interferents in biological media. Moreover, this reduced fluoresceinamine-based sensor has a high photostability and high dissociation constant, which is an indication that the complex obtained between reduced fluoresceinamine (RFL) and Fe(II) is highly stable. This fluorescence-based sensor has a binding mechanism of 1:1 and a positive cooperativity was found between analyte and sensor. The detection, quantification and sensitivity parameters of the sensor were determined: 21.6 ± 0.1 μM; 65.6 ± 0.1 μM and 48 ± 3 (×10

Topics: Cadmium Compounds; Ferrous Compounds; Fluorescent Dyes; Iron; Quantum Dots; Spectrometry, Fluorescence; Tellurium

In this work, cysteamine (CA) stabilized CdTe quantum dots (QDs) (CA-CdTe QDs) and sodium citrate stabilized gold nanoparticles (AuNPs) were prepared. Because of the strong electrostatic interaction and spectral overlap of emission spectrum of CA-CdTe QDs and absorption spectrum of AuNPs, a highly effective fluorescence resonance energy transfer (FRET) system was formed and the fluorescence of CA-CdTe QDs was strongly quenched. The synthesized CA-CdTe and AuNPs were self-assembled to large clusters due to the electrostatic attraction and the fluorescence of CA-CdTe was sharply quenched as a result of FRET. Under the optimum pH of 5.5, the positive GSH could assemble with negative AuNPs through electrostatic interaction and destroy the FRET system of CA-CdTe and AuNPs, due to the red shift of absorption wavelength of AuNPs caused by aggregation. The fluorescence of CA-CdTe recovered, and the recovered fluorescence efficiency shows a linear function against the GSH concentrations from 6.7 nM to 0.40 μM, with a detecting limit of 3.3 nM. The quenched emission of CA-CdTe could be recovered attributed to the aggregation of AuNPs by GSH. Under optimal conditions, the sensing system was successfully applied in the detection of GSH in real human blood plasma samples with a recovery of 99.5-102.3%, showing a promising future for the highly sensitive and selective GSH detection in the human blood plasma samples.

Topics: Biosensing Techniques; Cadmium Compounds; Cysteamine; Cysteine; Glutathione; Gold; Homocysteine; Humans; Metal Nanoparticles; Quantum Dots; Tellurium

Exploring effective methods for tetracycline (TC) detection in soil has great significance because of its emerging environmental problem and increasing threat to soil quality and general public health worldwide. In this work, a sensitive photoelectrochemical (PEC) aptasensor toward TC detection was designed and constructed based on an efficient photosensitive material of Z-scheme CdTe-BiOBr heterojunction. Due to the sensitization of CdTe quantum dots (QDs) on the BiOBr nanoflowers, the photocurrent intensity of the CdTe-BiOBr heterojunction was enhanced about 5.0-fold and 8.0-fold than that of pure BiOBr and CdTe under visible-light irradiation, which was attributed to the low electron-hole combination efficiency, high visible light utilization efficiency, and high carrier density of the heterojunction. On the merits of the excellent PEC activity of the CdTe-BiOBr and the specificity of the aptamer, the proposed PEC aptasensor has the advantages of satisfying linear range (from 10 to 1500 pM), low detection limit (9.25 pM), good selectivity, and reproducibility. In addition, acceptable accuracy was obtained for TC detection in real soil sample, giving acceptable accuracy in comparison with the referenced high-performance liquid chromatography-diode array detector method, revealing a promising avenue for accurate and ultrasensitive estimation of other kinds of contaminants in the broad field of analysis.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Bismuth; Cadmium Compounds; Electrochemical Techniques; Electrons; Limit of Detection; Quantum Dots; Reproducibility of Results; Soil; Tellurium; Tetracycline

Doping quantum dots (QDs) with extra element presents a promising future for their applications in the fields of environmental monitoring, commercial products and biomedical sciences. However, it remains unknown for the influence of doping on the molecular biocompatibility of QDs and the underlying mechanisms of the interaction between doped-QDs and protein molecules. Using the "one-pot" method, we synthesized N-acetyl-l-cysteine capped CdTe: Zn

Topics: Biocatalysis; Cadmium Compounds; Hydrogen Bonding; Protein Binding; Protein Structure, Tertiary; Quantum Dots; Static Electricity; Tellurium; Trypsin; Zinc

A dual-response ratiometric fluorescence imprinted sensor based on visible/near-infrared emission was established for ultrasensitive, selective and visual detection 4-nitrophenol (4-NP). The molecularly imprinted polymer was incorporated in the ratiometric sensing system consisting of visible emission carbon dots@zeolitic imidazolate framework-8 (CDs@ZIF-8) and near-infrared emission cadmium telluride (CdTe) quantum dots. The CDs@ZIF-8 enhanced the emission of CDs and the fluorescence sensing performance. Compared to short wavelength of fluorophore, the near-infrared emission CdTe is less interference caused by auto-fluorescence of sample. The ratiometric fluorescence imprinted sensor exhibited dual response for 4-NP at 420 nm and 703 nm and a wide concentration response range. Moreover, a good linear response was existed in the two concentration ranges of 0.1 pM-3.0 pM and 0.05 μM-30 μM with the detection limit of 0.08 pM and 0.05 μΜ, respectively. Significantly, the fluorescence color changes can be observed from purple to pink to red with the naked eye. The fluorescence quenching mechanism of the ratimetric fluorescence imprinted sensor was discussed in detail. The ratiometric fluorescence imprinted sensor was used to detect 4-NP in various real samples with satisfactory recoveries of 97.5-106.3%, which provided an interesting avenue for the rapid detection of pollutant with high sensitivity, high selectivity and visualization in real environment.

Topics: Biosensing Techniques; Cadmium Compounds; Limit of Detection; Metal-Organic Frameworks; Molecular Imprinting; Nitrophenols; Quantum Dots; Spectrometry, Fluorescence; Tellurium

In breast imaging applications, cadmium telluride (CdTe) photon counting x-ray detectors (PCDs) may reduce radiation dose and enable single-shot multi-energy x-ray imaging. The purpose of this work is to determine the upper limits of the detective quantum efficiency (DQE) of CdTe PCDs for x-ray mammography and to compare them with the published DQEs of energy-integrating detectors (EIDs) and other PCDs.. We calibrated and validated a Monte Carlo (MC) model of the DQE of CdTe PCDs using an XCounter CdTe PCD. Our model accounted for charge sharing, electronic noise, and charge summation logic. We used a 28 kVp Mo/Mo spectrum hardened by 3.9 cm of Lucite to optimize the detector thickness and energy threshold for pixel sizes of 50, 85, and 100. For an electronic noise level equal to that of the XCounter, the optimal DQE(0) without charge summing was 0.74. Charge summing for charge-sharing correction reduced DQE(0) by 14% due to an increase in electronic noise. Reducing the electronic noise to ∼0.5 keV per pixel in combination with charge summing resulted in DQE(0). (1) CdTe PCDs have the potential to provide a zero-frequency DQE equal to that of a-Se EIDs and slot-scanning silicon-strip PCDs, but this will require electronic noise levels ∼0.5 keV per pixel. (2) At mid-to-high spatial frequencies the DQE of CdTe PCDs may be (a) inferior to that of a-Se EIDs and slot-scanning silicon-strip PCDs in the slit direction, and (b) superior to slot-scanning silicon-strip PCDs in the scan direction.

Topics: Cadmium Compounds; Quantum Dots; Tellurium; X-Rays

Urgent identification of COVID-19 in infected patients is highly important nowadays. Förster or fluorescence resonance energy transfer (FRET) is a powerful and sensitive method for nanosensing applications, and quantum dots are essential materials in FRET-based nanosensors. The QDs are conjugated to DNA or RNA and used in many applications. Therefore, in the present study, novel fluorescence DNA-conjugated CdTe/ZnS quantum dots nanoprobe designed for detection of Covid-19 after extracting their RNA from saliva of hesitant people. For achieving this purpose, the water-soluble CdTe/ZnS QDs-DNA prepared via replacing the thioglycolic acid (TGA) on the surface of QDs with capture DNA (thiolated DNA) throw a ligand-exchange method. Subsequently, by adding the different concentrations of complementary (target DNA) in a mixture of quencher DNA (BHQ

Topics: Cadmium Compounds; COVID-19; DNA; Humans; Quantum Dots; SARS-CoV-2; Sulfides; Tellurium; Zinc Compounds

Perfluorooctanoic acid (PFOA) and Perfluorooctane sulfonate (PFOS) are two typical perfluorinated compounds (PFCs) that poss potential ecological toxicity. In this work, a fluorescence and resonance light scattering (RLS) dual-readout strategy for the detection of PFCs at picomole level based on the water-soluble CdTe quantum dots (CdTe QDs) has been proposed. It is found that the CdTe QDs exhibit a quenching in the presence of PFCs and thus serve as useful probes for PFCs. The linear ranges are 0.032-10.0 nM with a limit of detection(LOD) of 32.02 pM for PFOA and 0.044-15.0 nM with a LOD of 43.96 pM for PFOS, respectively. Meanwhile, PFCs can form complexes with CdTe QDs in acid medium, resulting in remarkable RLS signals. The enhanced RLS intensities are in proportion to the concentrations of PFOA and PFOS, respectively. And the linear ranges are 0.048-5.0 nM with a LOD of 47.78 pM for PFOA, and 0.057-5.0 nM with a LOD of 56.72 pM for PFOS, respectively. This dual-mode detection increases the reliability of the measurement. The proposed method is simple, sensitive and cost-effective, with potential applications in environmental monitoring and assessment.

Topics: Cadmium Compounds; Quantum Dots; Reproducibility of Results; Tellurium

To compare imaging performance of a cadmium telluride (CdTe) based photon counting detector (PCD) with a CMOS based energy integrating detector (EID) for potential phase sensitive imaging of breast cancer.. A high energy inline phase sensitive imaging prototype consisting of a microfocus X-ray source with geometric magnification of 2 was employed. The pixel pitch of the PCD was 55μm, while 50μm for EID. The spatial resolution was quantitatively and qualitatively assessed through modulation transfer function (MTF) and bar pattern images. The edge enhancement visibility was assessed by measuring edge enhancement index (EEI) using the acrylic edge acquired images. A contrast detail (CD) phantom was utilized to compare detectability of simulated tumors, while an American College of Radiology (ACR) accredited phantom for mammography was used to compare detection of simulated calcification clusters. A custom-built phantom was employed to compare detection of fibrous structures. The PCD images were acquired at equal, and 30% less mean glandular dose (MGD) levels as of EID images. Observer studies along with contrast to noise ratio (CNR) and signal to noise ratio (SNR) analyses were performed for comparison of two detection systems.. MTF curves and bar pattern images revealed an improvement of about 40% in the cutoff resolution with the PCD. The excellent spatial resolution offered by PCD system complemented superior detection of the diffraction fringes at boundaries of the acrylic edge and resulted in an EEI value of 3.64 as compared to 1.44 produced with EID image. At equal MGD levels (standard dose), observer studies along with CNR and SNR analyses revealed a substantial improvement of PCD acquired images in detection of simulated tumors, calcification clusters, and fibrous structures. At 30% less MGD, PCD images preserved image quality to yield equivalent (slightly better) detection as compared to the standard dose EID images.. CdTe-based PCDs are technically feasible to image breast abnormalities (low/high contrast structures) at low radiation dose levels using the high energy inline phase sensitive imaging technique.

Topics: Breast Neoplasms; Cadmium Compounds; Female; Humans; Phantoms, Imaging; Photons; Quantum Dots; Tellurium; X-Rays

The residue problem in animal food products caused by the abuse of chlortetracycline (CTC) is one of the food safety issues that have attracted much attention. Herein, a composite was generated by embedding CdTe quantum dots (QDs) into ZIF-8 for ratiometric fluorescent analysis of CTC. With adding CTC, the green luminescence of CTC appeared under the sensitization effect of Zn

Topics: Animals; Cadmium Compounds; Chlortetracycline; Fluorescent Dyes; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium

The combined detection of CA125, CEA and AFP is of great significance in the diagnosis of ovarian cancer. Photonic crystal (PhC) barcodes have apparent advantages in multiplex immunoassays of ovarian cancer markers. In this paper, a novel PhC barcode was assembled from dendritic silica nanoparticles (dSiO

Topics: Biomarkers, Tumor; Cadmium Compounds; Humans; Immunoassay; Nanoparticles; Ovarian Neoplasms; Quantum Dots; Reproducibility of Results; Silicon Dioxide; Tellurium

Quantum dots (QDs), with unique and tunable optical properties, have been widely used in many fields closely related to our daily lives, such as biomedical application and electronic products. Therefore, the potential toxicity of QDs on the human health should be understood. Autophagy plays an important role in cell survival and death. Endoplasmic reticulum autophagy (ER-phagy), a selective autophagy that degrades ER, responds to the accumulation of misfolded proteins and ER stress. Although many reports have revealed that autophagy can be disturbed by cadmium telluride (CdTe)-QDs and other nanomaterials, there are still lack more detailed researches to illustrate the function of autophagy in CdTe-QDs-treated cells, and the function of ER-phagy in CdTe-QDs-treated cells remains to be illustrated. On the basis of transcriptome analysis, we explored the effect of CdTe-QDs on Saccharomyces cerevisiae and first illustrated that both of autophagy and ER-phagy were protective mechanisms in CdTe-QDs-treated cells. It was found that CdTe-QDs inhibited the proliferation of yeast cells, disrupted homeostasis of cells, membrane integrity, and metabolism process. All of these can be reasons of the reduction of cell viability. The abolishment of autophagy and ER-phagy reduce the cell survival, indicating both of them are cell protective mechanisms against CdTe-QDs toxicity in yeast cells. Therefore, our data are significant for the application of CdTe-QDs and provide precious information for understanding of nanomaterials-related ER-phagy.

Topics: Autophagy; Cadmium Compounds; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Humans; Quantum Dots; Saccharomyces cerevisiae; Tellurium

In this work CdTe/ZnSe core/shell quantum dots (QDs) were synthesized via a simple, rapid and room temperature photochemical approach. Optical properties of aqueous prepared CdTe/ZnSe QDs were studied systematically under gamma irradiation with dose range of 0 Gy to 20 kGy. The obtained results showed a regular red shift behavior versus gamma irradiation dose, in photoluminescence peak and absorption edge of the CdTe/ZnSe QDs. Structural properties of CdTe/ZnSe QDs before and after gamma irradiation were characterized by means of X-ray diffraction (XRD), Raman and Fourier-transform infrared (FT-IR) analyses. The obtained results showed that the crystalline structure of CdTe/ZnSe core/shell QDs did not change after gamma irradiation. Concentration and shell thickness as two important factors on the sensitivity of CdTe/ZnSe QDs in front of gamma irradiation have been investigated. Based on this study, CdTe/ZnSe QDs are suggested as good candidates for gamma dosimeter.

Topics: Cadmium Compounds; Quantum Dots; Radiation, Ionizing; Selenium Compounds; Spectroscopy, Fourier Transform Infrared; Tellurium; Zinc Compounds

Owing to the high risk to human and environmental health, heavy metal pollution has become a global problem. Rapid, accurate and multiplexed determination of heavy metal ions is critical. In this work, we reported a promising approach to designing ratiometric fluorescent nanoprobes for multiplexed determination of Hg

Topics: Cadmium Compounds; Carbon; Humans; Ions; Metals, Heavy; Quantum Dots; Tellurium

A smartphone-assisted fluorescence color sensing system for rapid, convenient, and on-site detection of copper ions was developed. The ratiometric fluorescence sensor was fabricated by using silica-coated blue-light-emitting carbon dots and surface-grafted red-light-emitting cadmium-telluride quantum dots. After exposure to Cu

Topics: Biosensing Techniques; Cadmium Compounds; Carbon; Colorimetry; Copper; Fluorescence; Quantum Dots; Sensitivity and Specificity; Smartphone; Software; Tellurium; Ultraviolet Rays

Topics: Biosensing Techniques; Cadmium Compounds; Humans; Neoplastic Cells, Circulating; Quantum Dots; Tellurium

Recently, the use of CdTe quantum dots in the field of biomedicine, such as biological imaging, biosensors, cell markers, and drug carriers, is increasing due to their special physical and chemical properties. However, their biosafety assessment lags far behind their rapid application. In this study, we observed that CdTe quantum dots with certain exposed doses and time decreased the cell viability and increased the apoptosis rates in ND7/23 cells. In general, CdTe quantum dots exposure could promote the accumulation of reactive oxygen species (ROS) in cells and decrease the mitochondrial membrane potential, which led to pathological changes and subcellular organelle damages. We hypothesized that the mitochondrial pathway could be involved in CdTe quantum dots-induced apoptosis. The results suggested that CdTe quantum dots exposure increased the expression levels of three mitochondrial pathway markers, for example, caspase-3, cytochrome c, and Bax while decreased Bcl-2 protein expression, following with cytochrome c falling out of the inner membrane of mitochondrial and releasing into the cytoplasm. The application of caspase-3 protein inhibitor Ac-DEVD-CHO could decrease apoptosis rates in ND7/23 cells. The results, taken together, demonstrated that CdTe quantum dots could induce apoptosis of ND7/23 cells through the mitochondrial pathway. Our findings provide a novel insight for researchers to explore CdTe quantum dots' toxic mechanisms to reduce their adverse effects.

Topics: Apoptosis; Cadmium Compounds; Caspase 3; Cell Line; Cytochromes c; Ganglia, Spinal; Quantum Dots; Tellurium

Topics: Cadmium Compounds; Humans; Quantum Dots; Tellurium; Tetanus Toxoid

The risk assessment of cadmium (Cd)-based quantum dots (QDs) used for biomedical nanotechnology applications has stern toxicity concerns. Despite cytotoxicity studies of cadmium telluride (CdTe) QDs, the systematic in vivo study focusing on its organismal effects are more relevant to public health. Therefore, the present study aims to investigate the effect of chemically synthesized 3-mercapto propionic acid-functionalized CdTe QDs on organisms' survival, development, reproduction, and behaviour using Drosophila melanogaster as a model. The sub-cellular impact on the larval gut was also evaluated. First/third instar larvae or the adult Drosophila were exposed orally to green fluorescence emitting CdTe QDs (0.2-100 μM), and organisms' longevity, emergence, reproductive performance, locomotion, and reactive oxygen species (ROS), and cell death were assessed. Uptake of semiconductor CdTe QDs was observed as green fluorescence in the gut. A significant decline in percentage survivability up to 80% was evident at high CdTe QDs concentrations (25 and 100 μM). The developmental toxicity was marked by delayed and reduced fly emergence after CdTe exposure. The teratogenic effect was evident with significant wing deformities at 25 and 100 μM concentrations. However, at the reproductive level, adult flies' fecundity, fertility, and hatchability were highly affected even at low concentrations (1 μM). Surprisingly, the climbing ability of Drosophila was unaffected at any of the used CdTe QDs concentrations. In addition to organismal toxicity, the ROS level and cell death were elevated in gut cells, confirming the sub-cellular toxicity of CdTe QDs. Furthermore, we observed a significant rescue in CdTe QDs-associated developmental, reproductive, and survival adversities when organisms were co-exposed with N-acetyl-cysteine (NAC, an antioxidant) and CdTe QDs. Overall, our findings indicate that the environmental release of aqueously dispersible CdTe QDs raises a long-lasting health concern on the development, reproduction, and survivability of an organism.

Topics: Animals; Cadmium Compounds; Drosophila melanogaster; Quantum Dots; Tellurium

Basement membrane (BM) acts as a sheet-like extracellular matrix to support and promote the formation of epithelial and endothelial cell layers. The in vitro reconstruction of the BM is however not easy due to its ultrathin membrane features. This difficulty is overcome by self-assembling type IV collagen and laminin in the porous areas of a monolayer of crosslinked gelatin nanofibers deposited on a honeycomb microframe. Herein, a method is presented to generate airway epithelium by using such an artificial basement membrane (ABM) and human-induced pluripotent stem cells (hiPSCs). Bipolar primordial lung progenitors are firstly induced from hiPSCs and then replated on the ABM for differentiation toward matured airway epithelium under submerged and air-liquid interface culture conditions. As a result, a pseudostratified airway epithelium consisting of several cell types is achieved, showing remarkable apical secretion of MUC5AC proteins and clear advantages over other types of substrates. As a proof of concept, the derived epithelium is used for toxicity test of cadmium telluride (CdTe) nanoparticles (NPs), demonstrating the applicability of ABM-based assays involving hiPSC-derived epithelial cells-based assays.

Topics: Basement Membrane; Cadmium Compounds; Cell Differentiation; Epithelium; Humans; Laminin; Quantum Dots; Tellurium; Toxicity Tests

Methyl nicotinate (MN) is a representative and typical volatile organic marker of Mycobacterium tuberculosis, and the specific detection of MN in human breath facilitates non-invasive, rapid, and accurate epidemic screening of tuberculosis infection. Herein, we constructed a fluorescent assay consisted of CdTe quantum dots (QD) and cobalt-metalized tetrakis(4-carboxyphenyl) porphyrin (CoTCPP) nanosheets to determine methyl nicotinate (MN) in vapor samples. Red-emission QD (λ

Topics: Biomarkers; Cadmium Compounds; Humans; Mycobacterium tuberculosis; Nanoparticles; Nicotinic Acids; Porphyrins; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Volatilization

Topics: Cadmium; Cadmium Compounds; Chemical and Drug Induced Liver Injury; Humans; Hydrogen Peroxide; Oxidation-Reduction; Oxidative Stress; Peroxiredoxins; Quantum Dots; Tellurium; Thioredoxins

In order to prepare a kind of efficient fluorescence sensors for determination of cis-diol-containing flavonoids, novel imprinted quantum dots for myricetin (Myr) were prepared based on boronate affinity-based template-immobilization surface imprinting. The obtained boronate affinity-based surface imprinted silica (imprinted APBA-functionalized CdTe QDs) was used as recognition elements. The quantum dots were used as signal-transduction materials. Under the optimum conditions, according to fluorescence quenching of imprinted APBA-functionalized CdTe QDs by Myr, the imprinting factor (IF) for Myr was evaluated to be 7.88. The result indicated that the boronate affinity functionalized quantum dots coated with imprinted silica were successfully prepared. The prepared imprinted APBA-functionalized CdTe QDs exhibited good sensitivity and selectivity for Myr. The fluorescence intensity was inversely proportional to the concentration of Myr in the 0.30-40 μM concentration range. And its detection limit was obtained to be 0.08 μM. Using the fluorescence sensors, the detection of Myr in real samples was successfully carried out, and the concentration of Myr in green tea and apple juice samples was evaluated to be 2.26 mg/g and 0.73 mg/g, respectively. The recoveries for the spiked green tea and apple juice samples were 95.2-105.0% and 91.5-111.0%, respectively. This study also provides an efficient fluorescent detection method for cis-diol-containing flavonoids in real samples.

Topics: Cadmium Compounds; Flavonoids; Limit of Detection; Molecular Imprinting; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) have gained increased attention for their extensive biomedical and electronic products applications. Due to the high priority of QDs in contacting the circulatory system, understanding the hemocompatibility of QDs is one of the most important aspects for their biosafety evaluation. Thus far, the effect of QDs on coagulation balance haven't been fully understood, and limited studies also have yet elucidated the potential mechanism from the perspective of interaction of QDs with coagulation-related proteins.. QDs induced the derangement of coagulation balance by prolonging the activated partial thromboplastin time and prothrombin time as well as changing the expression levels of coagulation and fibrinolytic factors. The contact of QDs with PTM (prothrombin), PLG (plasminogen) and FIB (fibrinogen) which are primary coagulation-related proteins in the coagulation and fibrinolysis systems formed QDs-protein conjugates through hydrogen-bonding and hydrophobic interaction. The affinity of proteins with QDs followed the order of PTM > PLG > FIB, and was larger with CdTe/ZnS QDs than CdTe QDs. Binding with QDs not only induced static fluorescence quenching of PTM, PLG and FIB, but also altered their conformational structures. The binding of QDs to the active sites of PTM, PLG and FIB may promote the activation of proteins, thus interfering the hemostasis and fibrinolysis processes.. The interactions of QDs with PTM, PLG and FIB may be key contributors for interference of coagulation balance, that is helpful to achieve a reliable and comprehensive evaluation on the potential biological influence of QDs from the molecular level.

Topics: Cadmium Compounds; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Semiconductor quantum dots (QDs) and tungsten disulfide nanosheets (WS

Topics: Aptamers, Nucleotide; Cadmium Compounds; Crops, Agricultural; Edible Grain; Electrons; Fluorescence; Limit of Detection; Quantum Dots; Sulfides; Tellurium; Tungsten Compounds; Zearalenone

CdTe@CdS core-shell quantum dots with different particle sizes are synthesized by an aqueous method, and coating them with a CdS shell layer improves the quantum yield (36% → 59%) and fluorescence stability (37% → 77%) of CdTe@CdS quantum dots. When the KCl concentration (mass fraction) in the system is 15%, the CdTe@CdS quantum dot dispersion system remains in the liquid state at -20 °C, and the low temperature increases the fluorescence intensity. A QD-Ab probe is obtained after CdTe@CdS quantum dots are coupled with IgG; the circular dichroism shows that the IgG protein structure is not destroyed, while capillary electrophoresis, agarose gel electrophoresis and flow cytometry verify the conjugation efficiency. With rabbit anti-mouse EMR1 antibody as the primary antibody and QD-Ab as the secondary antibody, the hepatic macrophages in liver frozen sections are fluorescently labeled at -20 °C, and it is found that they are radially distributed in hepatic sinusoids with specific and highly efficient labeling; these results are verified by H&E staining and TEM. This technology can provide important technical support for in-depth understanding of the distribution of liver immune cells in the liver, and it can further provide a scientific basis to understand the relationship between the liver structure and function and pathological changes.

Topics: Animals; Cadmium Compounds; Freezing; Frozen Sections; Immunoglobulin G; Liver; Macrophages; Mice; Quantum Dots; Rabbits; Sulfides; Tellurium

The contamination of food and potable water with microorganisms may cause food-borne and water-borne diseases. The common contaminants include Escherichia coli (E. coli), Salmonella sp. etc. The conventional methods for monitoring the water quality for the presence of bacterial contaminants are time-consuming, expensive, and not suitable for rapid on-spot detection in field conditions. In the current study, super paramagnetic iron oxide nanoparticles (SPIONs) were synthesized and conjugated with E. coli specific Aptamer I to detect E. coli cells qualitatively as well as quantitatively. The sludge consisting of E. coli- SPION complex was separated via magnetic separation. The presence of E. coli cells was confirmed with the help of standard techniques and confocal laser scanning microscopy (CLSM) employing Aptamer II conjugated CdTe-MPA quantum dots (QDs). Finally, an ATmega 328P prototype biosensor based on Aptamer II conjugated CdTe MPA QDs exhibited quantitative and qualitative abilities to detect E.coli. This prototype biosensor can even detect low bacterial counts (up to 1 × 10

Topics: Biosensing Techniques; Cadmium Compounds; Escherichia coli; Escherichia coli Infections; Humans; Magnetite Nanoparticles; Quantum Dots; Tellurium

Decreased automaticity is common among individuals with neurodegenerative disease and is often assessed using dual-task (DT) paradigms. However, the best methods for assessing performance changes related to DT demands remain inconclusive.. To investigate the reliability and validity of a novel battery of DT measures (DT Effect-Battery (DTE-B)) encompassing three domains: task-specific interference, task prioritization, and automaticity.. Data for this retrospective cross-sectional study included 125 participants with Parkinson's disease (PD), 127 participants with Alzheimer's disease (AD), and 84 healthy older adults. Reliability analyses were conducted using a subset of each population. DTE-B measures were calculated from single and DT performance on the Timed Up and Go test and a serial subtraction task. Construct validity was evaluated via associations within the DTE-B and with theoretically supported measures as well as known-groups validity analyses.. Good to excellent reliability was found for DTE-B measures of task interference (motor and cognitive DT effects) (ICCs≥.658) and automaticity (combined DT effect (cDTE)) (ICCs≥.938). Evidence for convergent validity was found with associations within the hypothesized constructs. Known-groups validity analyses revealed differences in the DTE-B among the healthy group and PD and AD groups (. This study provides evidence to support the DTE-B as a reliable measure of multiple constructs pertinent to DT performance. The cDTE demonstrated evidence to support its validity as a measure of automaticity. Further investigation of the utility of the DTE-B in both PD and AD, as well as other populations, is warranted.

Topics: Aged; Alzheimer Disease; Cadmium Compounds; Cross-Sectional Studies; Gait; Humans; Neurodegenerative Diseases; Parkinson Disease; Postural Balance; Quantum Dots; Reproducibility of Results; Retrospective Studies; Tellurium; Time and Motion Studies; Walking

Neutron Capture Enhanced Particle Therapy (NCEPT) boosts the effectiveness of particle therapy by capturing thermal neutrons produced by beam-target nuclear interactions in and around the treatment site, using tumour-specific [Formula: see text]B or [Formula: see text]Gd-based neutron capture agents. Neutron captures release high-LET secondary particles together with gamma photons with energies of 478 keV or one of several energies up to 7.94 MeV, for [Formula: see text]B and [Formula: see text]Gd, respectively. A key requirement for NCEPT's translation is the development of in vivo dosimetry techniques which can measure both the direct ion dose and the dose due to neutron capture. In this work, we report signatures which can be used to discriminate between photons resulting from neutron capture and those originating from other processes. A Geant4 Monte Carlo simulation study into timing and energy thresholds for discrimination of prompt gamma photons resulting from thermal neutron capture during NCEPT was conducted. Three simulated [Formula: see text] mm[Formula: see text] cubic PMMA targets were irradiated by [Formula: see text]He or [Formula: see text]C ion beams with a spread out Bragg peak (SOBP) depth range of 60 mm; one target is homogeneous while the others include [Formula: see text] mm[Formula: see text] neutron capture inserts (NCIs) of pure [Formula: see text]B or [Formula: see text]Gd located at the distal edge of the SOBP. The arrival times of photons and neutrons entering a simulated [Formula: see text] mm[Formula: see text] ideal detector were recorded. A temporal mask of 50-60 ns was found to be optimal for maximising the discrimination of the photons resulting from the neutron capture by boron and gadolinium. A range of candidate detector and thermal neutron shielding materials were simulated, and detections meeting the proposed acceptance criteria (i.e. falling within the target energy window and arriving 60 ns post beam-off) were classified as true or false positives, depending on their origin. The ratio of true/false positives ([Formula: see text]) was calculated; for targets with [Formula: see text]B and [Formula: see text]Gd NCIs, the detector materials which resulted in the highest [Formula: see text] were cadmium-shielded CdTe and boron-shielded LSO, respectively. The optimal irradiation period for both carbon and helium ions was 1 µs for the [Formula: see text]B NCI and 1 ms for the [Formula: see text]Gd NCI.

Topics: Boron; Cadmium Compounds; Monte Carlo Method; Neutrons; Quantum Dots; Tellurium

Topics: Algorithms; Cadmium Compounds; Quantum Dots; Tellurium; Tomography, X-Ray Computed

A turn-on fluorescent sensor based on CdTe quantum dots (QDs) is designed for highly sensitive and selective ascorbic acid (AA) detection. CdTe shows a strong emission centered at 578 nm. When assembled with poly(sodium 4-styrenesulfonate) (PSS) and methyl viologen (Mv

Topics: Ascorbic Acid; Cadmium Compounds; Fluorescence; Humans; Limit of Detection; Oxidation-Reduction; Paraquat; Quantum Dots; Spectrometry, Fluorescence; Tellurium

This work firstly developed a near-infrared fluorescence capillary imprinted sensor with high selectivity and sensitivity for the chiral recognition of l-histidine. The near-infrared fluorescence imprinted polymer prepared by sol-gel method using CdTe quantum dots as the near-infrared fluorescence source was self-sucked into activated capillary to form the fluorescence imprinted capillary. The fluorescence imprinted capillary sensor had higher fluorescence response efficiency. With the superior stability, reproducibility and reusability, the fluorescence capillary imprinted sensor displayed higher selectivity toward l-histidine. Under the optimal conditions, the fluorescence intensity (λex = 370 nm, λem = 695 nm) of the fluorescence capillary imprinted sensor was enhanced in proportion to l-histidine concentration ranged from 0.1 pM to 1.8 pM with a limit of detection of 0.08 pM. Spiking experiment showed that the fluorescence capillary imprinted sensor was successfully used for determination of l-histidine in human urine and serum with the recoveries of 99.6-102.7%. The near-infrared fluorescence capillary imprinted sensor possessed significantly potential for high sensitive detection of l-histidine, which realized trace-level analysis for micro-volume sample and provided promising utility for green chemical.

Topics: Cadmium Compounds; Histidine; Humans; Molecular Imprinting; Quantum Dots; Reproducibility of Results; Tellurium

Cadmium telluride quantum dots (CdTe QDs) exist in the environment due to the abandonment of products. There is a potential risk to organisms and toxic mechanism is worth exploring. In this study, 12.5 μmol/Kg body weight CdTe QDs triggered systemic and local inflammatory response in mice and activated macrophages, then the mechanism of activating macrophages to overexpress IL-1β and IL-6 was explored. RAW264.7 macrophages were used, and after macrophages exposing to 1 μM CdTe QDs for 24 h, oxidative stress occurred. Further investigation found that CdTe QDs triggered ferroptosis in RAW264.7 cells. And deferoxamine mesylate alleviated the excessive lipid hydroperoxide caused by QDs. Mechanistically, CdTe QDs-provoked decrease of nuclear factor erythroid 2-related factor 2 (NRF2) elicited phosphorylation of extracellular regulated protein kinases1/2 (ERK1/2) and then activated ferritinophagy, which made ferritin heavy chain 1 (FTH1) degraded in lysosome and proteasome to release free iron ions to initiate ferroptosis in macrophages. This paper updates the mechanism of macrophage activation by CdTe QDs with regard to ferritinophagy, and more importantly, identifies the key role of NRF2 and ERK1/2. Our research extends the role of ferroptosis in inflammatory responses triggered by nanoparticles (NPs) in macrophages and provides insightful reference for toxicity assessment of NPs.

Topics: Animals; Cadmium Compounds; Ferroptosis; Inflammation; Macrophages; Mice; NF-E2-Related Factor 2; Quantum Dots; Tellurium

Quantum dots (QDs), also known as semiconductor QDs, have specific photoelectricproperties which find application in bioimaging, solar cells, and light-emitting diodes (LEDs). However, the application of QDs is often limited by issues related to health risks and potential toxicity. The purpose of this study was to provide evidence regarding the safety of cadmium telluride (CdTe) QDs by exploring the detailed mechanisms involved in its hepatotoxicity. This study showed that CdTe QDs can increase reactive oxygen species (ROS) in hepatocytes after being taken up by hepatocytes, which triggers a significant mitochondrial-dependent apoptotic pathway, leading to hepatocyte apoptosis. CdTe QDs-induce mitochondrial cristae abnormality, adenosine triphosphate (ATP) depletion, and mitochondrial membrane potential (MMP) depolarization. Meanwhile, CdTe QDs can change the morphology, function, and quantity of mitochondria by reducing fission and intimal fusion. Importantly, inhibition of ROS not only protects hepatocyte viability but can also interfere with apoptosis and activation of mitochondrial dysfunction. Similarly, the exposure of CdTe QDs in Institute of Cancer Research (ICR) mice showed that CdTe QDs caused oxidative damage and apoptosis in liver tissue. NAC could effectively remove excess ROS could reduce the level of oxidative stress and significantly alleviate CdTe QDs-induced hepatotoxicity in vivo. CdTe QDs-induced hepatotoxicity may originate from the generation of intracellular ROS, leading to mitochondrial dysfunction and apoptosis, which was potentially regulated by mitochondrial dynamics. This study revealed the nanobiological effects of CdTe QDs and the intricate mechanisms involved in its toxicity at the tissue, cell, and subcellular levels and provides information for narrowing the gap between in vitro and in vivo animal studies and a safety assessment of QDs.

Topics: Animals; Apoptosis; Cadmium Compounds; Chemical and Drug Induced Liver Injury; Mice; Mitochondria; Quantum Dots; Reactive Oxygen Species; Tellurium

Despite the potential of cadmium telluride quantum dots (CdTe QDs) in bioimaging and drug delivery, their toxic effects have been documented. It is known that the immunotoxicity of CdTe QDs targeting macrophages is one of their adverse effects, and the protein corona (PC) will affect the biological effects of QDs. In order to prove whether the PC-CdTe QDs complexes could alleviate the toxicity of CdTe QDs without weakening their luminescence, we investigated the impact of protein corona formed in fetal bovine serum (FBS) on the cytotoxicity of CdTe QDs to mitochondria. RAW264.7 cells were used as the model to compare the effects of CdTe QDs and PC-CdTe QDs complexes on the structure, function, quantity, morphology, and mitochondrial quality control of mitochondria. As result, the protein corona form in FBS alleviated the inhibition of CdTe QDs on mitochondrial activity, the damage to mitochondrial membrane, the increase of ROS, and the reduction of ATP content. Also, CdTe QDs increased the number of mitochondria in macrophages, while the complexes did not. In line with this, the morphology of mitochondrial network in macrophages which were exposed to CdTe QDs and PC-CdTe QDs complexes was different. CdTe QDs transformed the network into fragments, punctuations, and short rods, while PC-CdTe QDs complexes made the mitochondrial network highly branched, which was related to the imbalance of mitochondrial fission and fusion. Mechanically, CdTe QDs facilitated mitochondrial fission and inhibited mitochondrial fusion, while protein corona reversed the phenomenon caused by QDs. Besides mitochondrial dynamics, mitochondrial biogenesis and mitophagy were also affected. CdTe QDs increased the expression of mitochondrial biogenesis signaling molecules including PGC-1α, NRF-1 and TFAM, while PC-CdTe QDs complexes played the opposite role. With regard to mitophagy, they both showed promoting effect. In conclusion, the formation of protein corona alleviated the toxic effects of CdTe QDs on the mitochondria in macrophages and affected mitochondrial quality control. Under the premise of ensuring the fluorescence properties of CdTe QDs, these findings provided useful insight into reducing the toxicity of CdTe QDs from two perspectives: protein corona and mitochondria, and shared valuable information for the safe use of QDs.

Topics: Cadmium Compounds; Macrophages; Mitochondria; Protein Corona; Quantum Dots; Tellurium

The present study demonstrate the first time usage of poly (HPMA-s-GPMA) copolymer for the fabrication of three-component based aptasensor for simple, selective, rapid and label free detection of arsenite (As

Topics: Acrylamides; Aptamers, Nucleotide; Arsenic; Biosensing Techniques; Cadmium Compounds; Limit of Detection; Quantum Dots; Tellurium

Although quantum dots (QDs) have shown great potential for various biomedical applications, their potential toxicity still needs to be comprehensively investigated. Previous studies showed that intravenous exposure of CdTe QDs at low concentration did not lead to obvious in vivo toxicity in the long term. However, the influence of CdTe QDs on the gut microbiota and the intestine is still unknown. Here, we explored whether single intravenous injection of CdTe QDs at low concentration can affect the gut microbiota and intestine of mice in short term. The results showed that CdTe QDs caused an imbalance of gut microbiota, especially the rapid increase in Lactobacillus on day 1 post-treatment. Meanwhile, the intestine exhibited the promotion of oxidative stress, inflammatory response, and hemorrhaging on days 5 and 15. These results demonstrate that the gut microbiota and the intestine are very sensitive to the toxicity of low-concentration CdTe QDs. This study provides further insight and method for the biosafety evaluation of nanomaterials.

Topics: Animals; Cadmium Compounds; Dysbiosis; Gastrointestinal Microbiome; Intestines; Mice; Quantum Dots; Tellurium

Molecular tags such as fluorophores are increasingly being replaced with nanoparticles thanks to their superior optical properties, substantial chemical stability, and stability against photobleaching. Herein, we innovatively constructed a new ratiometric fluorescence enzyme-linked immunosorbent assay (RF-ELISA) for the screening of alpha-fetoprotein (AFP) in early hepatocellular carcinoma

Topics: alpha-Fetoproteins; Cadmium Compounds; Carbon; Enzyme-Linked Immunosorbent Assay; Glucose Oxidase; Humans; Hydrogen Peroxide; Nanospheres; Quantum Dots; Reproducibility of Results; Silicon Dioxide; Tellurium

Colloidal semiconductor ternary CdTeS magic-size clusters (MSCs) have not been reported. Here, we present the first synthesis of CdTeS MSCs at room temperature and our understanding of the evolution pathway. The MSCs exhibit sharp optical absorption peaking at 381 nm and are labeled MSC-381. CdTeS MSC-381 evolves when pre-nucleation-stage samples of binary CdTe and CdS that do not contain quantum dots (QDs) are separately prepared and then mixed and incubated at room temperature. We propose that CdTeS MSC-381 evolves from its precursor compound (PC) via quasi-isomerization. Synchrotron-based small-angle X-ray scattering suggests that PCs/MSCs of CdTe and CdTeS are similar in sizes. We propose further that the CdTeS PC forms from the substitution reaction between the CdTe PC and the CdS monomer/fragment (Mo/Fr). The present study paves the way to the room-temperature evolution of ternary MSCs and provides an in-depth understanding of the PC to MSC transformation.

Topics: Cadmium Compounds; Quantum Dots; Tellurium; Temperature

Endoplasmic reticulum autophagy (ER-phagy) is an important strategy for cells against ER stress and maintain ER homeostasis. ER stress is considered as a potential toxicity of nanoparticles, but only a few studies have explored whether the nanoparticles-induced ER stress can trigger ER-phagy, and the precise molecular mechanism of ER-phagy mediated by nanoparticle-induced ER stress is still poorly understood. Therefore, our study focuses on the relationship between ER stress and ER-phagy caused by emerging nanoparticles CdTe-QDs and its molecular mechanism. The results showed that the accumulation of ROS and ER stress induced by CdTe-QDs contributed to the activation of autophagy and ER-phagy. Importantly, our study unraveled that CdTe-QDs activate autophagy by up-regulating the transcription of core autophagy machinery. It was found that the induced ER-phagy was mediated by Atg11/Atg40/Lst1-Sec23 instead of the autophagy machinery genes. We speculated that the ER-phagy caused by CdTe-QDs may include micro-ER-phagy and macro-ER-phagy. Collectively, this work provided valuable information for the application of CdTe-QDs in the field of biology and a theoretical basis for further understanding of ER-phagy.

Topics: Autophagy; Cadmium Compounds; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Quantum Dots; Saccharomyces cerevisiae; Tellurium

Topics: alpha-Fetoproteins; Biocatalysis; Biomarkers, Tumor; Cadmium Compounds; Carcinoma, Hepatocellular; Glypicans; Humans; Liver Neoplasms; Quantum Dots; Tellurium

Traction and quantitative detection of trace amount of target cells inside of biochip system in real-time has been a challenge for biomedical and clinical researchers. In this manuscript, we report fabrication of a photoelectrochemical platform that has integrated both biometric recognition and signal acquisition through microfabrication technology. In this chip, a ternary ZnO/CdTe/Bi nanorod array is fabricated, which significantly extends the absorption wavelength from the UV to the visible and even near-infrared regions for both photocarrier generation and surface plasmon resonance, ultimately achieving the amplification of initial photocurrent responses. The artificially designed aptamers with amino groups are assembled on the surface of the outermost Bi nanoparticles, which are used as signal probes due to the specific recognition to the nasopharyngeal carcinoma 5-8F cell. We demonstrate that different concentration of 5-8F cells is captured by aptamers, and the signal changes accordingly with the amount of the cells that have been trapped. As a result, the proposed biochip demonstrates rapid response in a wide linear range of 10

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Humans; Limit of Detection; Microfluidics; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Quantum Dots; Tellurium; Zinc Oxide

Thin-film cadmium telluride (CdTe) offers high average electron density, direct detection configuration, and excellent radiation hardness, making it an attractive material for radiation detectors. Although a very thin detector provides capabilities to conduct high-resolution measurements in high-energy radiation fields, it is limited by a low signal, often boosted with a front metal converter enhancing X-ray absorption. An extension of this approach can be explored through the investigation of electron backscattering phenomenon, known to be highly dependent on the material atomic number Z. Adding an electron reflector in tandem with the back electrode is proposed to be utilized for the detector signal enhancement.. We investigated the possibility of augmenting the fluence of electrons traversing CdTe thin film and thus increasing the detected signal pursuing two pathways: (1) adding a high-Z metal layer to the back of the detector surface, and (2) adding a top low-Z material to the detector layer to return its backscattered electrons. Copper (Cu) and lead (Pb) layers of varying thickness were investigated as potential metal back-reflectors, whereas polymethyl methacrylate (PMMA) water phantom material was tested as the top cover in multilayer detector structures.. The Monte Carlo (MC) radiation transport package MCNP5 was first used to model a basic multilayer structure of a CdTe-sensitive volume surrounded by PMMA, under a 6-MV photon beam. Addition of Cu or Pb back-reflectors allowed for the analysis of the signal enhancement and associated changes in Compton electrons fluence spectra. Related backscattering coefficients were then calculated using EGSnrc MC user-code for monoenergetic electron sources. Analytical functions were established to represent the best fitting curves to the simulation data. Finally, electron backscattering data was related to signal enhancement in the CdTe sensitive layer based on a semiquantitative approach.. We studied multilayer detector structures, decoupling the effects of PMMA and the back-reflector metals, Cu or Pb, on electron backscattering for electron energy range of up to 500 keV or 1 MeV depending on the choice of metal. Adding a 100-200-µm-thick metal film below the detector sensitive volume increased the fraction of reflected electrons, especially in the low, 100-200 keV, energy range. The thickness dependence of backscattering coefficients from thin films exhibits saturations at values significantly exceeding the electron ranges. That effect was related to the large-angle electron scattering. A detailed simulation of energy deposition revealed that the modified structures using Cu and Pb increased energy deposition by ∼10% and 75%, respectively. We have also established a linear dependence between the energy deposition in the semiconductor layer and the fluence of backscattered electrons in the corresponding multilayer structure. The low-Z top layer in practically implemental thicknesses of tens of micrometers has a positive effect due to partial electron reflection back to the semiconductor layer.. Signal enhancement in a thin-film CdTe radiation detector could be achieved using electron backscattering from metal reflectors. The methodology explored here warrants further studies to quantify achievable signal enhancement for various thin films and other small sensitive volume detectors.

Topics: Cadmium Compounds; Copper; Electrons; Lead; Monte Carlo Method; Photons; Polymethyl Methacrylate; Quantum Dots; Radiometry; Tellurium; Water

Ion imprinting technology was integrated on a rotational microfluidic paper- and cloth-based hybrid chip for the sensitive and selective detection of hexavalent chromium (Cr(VI)) ions. The rotational microfluidic hybrid chip consisted of CdTe quantum dot based ion imprinting fluorescence sensing cloth and three layers of paper. Users can collect fluorescence signals conveniently

Topics: Cadmium Compounds; Chromium; Ions; Microfluidics; Quantum Dots; Tellurium

In the current study, the cytotoxicity and mechanisms of cadmium telluride quantum dots (CdTe QDs) on RSC96 cells were evaluated by exposing different doses of CdTe QDs for 24 h. Two types of cell death, including apoptosis and autophagy, as well as two important organelles, mitochondria and endoplasmic reticulum, were focused after CdTe QDs exposure. The results showed that CdTe QDs induced apoptosis in RSC96 cells in a concentration-dependent manner; promoted the accumulation of intracellular reactive oxygen species; decreased the mitochondrial membrane potential; caused the release of cytochrome c; and also increased the expression of Bcl-2 associated X protein, caspase-3, and cytochrome c proteins and decreased the expression of Bcl-2 protein. Further results also confirmed that CdTe QDs could be internalized by RSC96 cells, and the exposure and internalization of CdTe QDs could induce excessive endoplasmic reticulum stress in the cells, and the expression levels of binding immunoglobulin protein, C/EBP homologous protein, and caspase12 proteins were increased in a concentration-dependent manner. Moreover, autophagy-related proteins LC3II, Beclin1, and P62 all increased after CdTe QDs exposure, suggesting that CdTe QDs exposure both promoted autophagosome formation and inhibited autophagosome degradation, and that CdTe QDs affected the autophagic flow in RSC96 cells. In conclusion, CdTe QDs are able to cause apoptosis and autophagy in RSC96 cells through mitochondrial and endoplasmic reticulum stress pathways, and the possible neurotoxicity of CdTe QDs should be further investigated.

Topics: Apoptosis; Autophagy; Cadmium Compounds; Cytochromes c; Endoplasmic Reticulum Stress; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Quantum Dots; Rats; Schwann Cells; Tellurium

In this study, we aimed to increase the knowledge regarding the response mechanisms which were associated with the formation of CdS thin films. CdS thin film remains the most appealing alternative for many researchers, as it has been a capable buffer material for effect in film based polycrystalline solar cells (CdTe, CIGSe, CZTS). The Linker Assisted and Chemical Bath Deposition (LA-CBD) technique, which combines the Linker Assisted (LA) technique and the chemical bath deposition (CBD) method for forming high quality CdS thin film, was presented as an efficient and novel hybrid sensitization technique. CdS films were bound to soda lime with the help of electrostatic forces, which led to the formation of the intermediate complexes [Cd (NH

Topics: Cadmium Compounds; Quantum Dots; Salvia; Sulfides; Tellurium

A novel dual-emission ratiometric fluorescent sensor for biogenic amines (BAs) was prepared by simple mixing blue fluorescent carbon dots (CDs) and yellow fluorescent CdTe quantum dots (CdTe QDs). Based on different sensitive properties of pH, CdTe QDs and CDs were used as the response signal and internal reference signal, respectively. The developed ratiometric fluorescent sensor achieved quantitative analysis of eight kinds of BAs with rapid response (30 s) and low limits of detection (1.259-5.428 μM). Furthermore, color-tunable fluorescent test strips were constructed by easily assembling CDs and CdTe QDs onto filter paper. The obtained smart label showed a distinguishable fluorescent color variation from blue to green during the corruption of shrimp samples. The smart label with advantages of convenience and rapidness provided a method for visually monitoring the freshness of food samples.

Topics: Biogenic Amines; Cadmium Compounds; Carbon; Fluorescent Dyes; Quantum Dots; Tellurium

Inducing apoptosis in cancer cells is considered a potential therapeutic mechanism underlying cancers. Here, chiral folic acid (FA) conjugated Cys-CdTe/CdS quantum dots (QDs) conjugated with a cancer-targeting ligand were fabricated to induce apoptosis in vivo. Ligand-induced chirality mechanism for FA-Cys-CdTe/CdS QDs was discussed, which is verified by density functional theory (DFT) simulation. Interestingly, we found that the circular dichroism (CD) signals of chiral QDs can effectively distinguish breast cancer cells from normal cells, where a sharp decrease in CD signal and absorption intensity can be seen. Notably, chiral FA-Cys-CdTe/CdS QDs showed significant apoptosis-inducing ability after the release of mitochondrial apoptotic factors. Furthermore, in vivo experiments showed that chiral FA-Cys-CdTe/CdS QDs provide an efficient cancer ablation through the apoptosis process with negligible toxicity, demonstrating their great potential utility in targeted anticancer agent for future clinic application.

Topics: Cadmium Compounds; Folic Acid; Ligands; Neoplasms; Quantum Dots; Tellurium

Inorganic-based thin-film photovoltaics (TFPV) represents an important component of the growing low-carbon energy market and plays a vital role in the drive toward lower cost and increased penetration of solar energy. Yet, commercialized thin-film absorber technologies suffer from some non-ideal characteristics, such as toxic or non-abundant element use (

Topics: Cadmium Compounds; Prospective Studies; Quantum Dots; Tellurium

Sensitive and accurate detection of cancer cells is of great significance for the early diagnosis and treatment of cancer. In this work, we developed a simple fluorescent signal amplification biosensor based on an entropy-driven three-dimensional (3D) multipedal-DNA walker for highly sensitive detection of cancer cells. Firstly, DNA tetrahedron nanostructures (DTNs) combined with AS1411 aptamer were used as the capture probe to achieve efficient capture of cancer cells. Then, the bipedal hairpin fuel chain hybridized with DTNs and exposed two catalytic "legs" to form a walker probe. Finally, the walker probe autonomously walked on polystyrene microspheres (PS) via entropy-driven catalytic reaction. DTNs rolled on the PS to achieve multipedal walking, realizing fluorescence signal amplification due to fluorescence recovery of DNA-CdTe quantum dots on the PS surface. This fluorescence signal amplification strategy showed excellent selectivity and sensitivity toward cancer cells with the detection limit of 7 cell mL

Topics: Biomarkers, Tumor; Cadmium Compounds; DNA; Entropy; Limit of Detection; Neoplasms; Polystyrenes; Quantum Dots; Tellurium

Chiral recognition has long been a challenging issue to deal with in biological systems, drug design and food authentication. Implementing nanoparticle-based probes with intrinsic or induced chirality in this field has addressed several issues concerning sensitivity, reliability, rapidness and the cost of chiral sensing platforms. Yet, research into chiral nanoprobes that can be used for visual monitoring of chiral substances is still in its infancy. As part of this study, a visual chiral recognition platform has been developed in which a combination of blue-emitting carbon dots (BCDs) and mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs) with inherent chiroptical activity were employed for enantiomeric detection. The ratiometric probe displayed unique fluorescence response patterns in the presence of arginine (Arg) and histidine (His) enantiomers. Upon addition of l-amino acids, successive enhancement and quenching of emission intensity as well as a red-shift in emission wavelength of MPA-QDs were observed. The emission color of the nanoprobe changed from green to pink-red and green to brick-red red by increasing the concentration of L-Arg and L-His, respectively. In contrast, their d-amino acid equivalents have a negligible influence on the emission color and fluorescence signal of the developed nanoprobe. Due to the enantioselective vibrant color changes of the nanoprobe, RGB analysis was applied for the determination of enantiomeric excess (ee) in racemic mixture with satisfactory results, allowing smartphone-based onsite visual evaluation of ee (%). Circular dichroism, lifetime, size distribution and ζ-potential measurements were employed to study the chiroselective responses. First-principle calculations were also carried out with density functional theory (DFT) to confirm the experimental observation. Furthermore, chiroselective response patterns of the ratiometric nanoprobe were manipulated to construct a logic gate system mimicking AND, OR, and INHIBIT functions. The capability of the proposed chiral platform in visual monitoring of the fraction of enantiomers in racemic mixtures has a great potential for rapid and onsite visual discrimination of chiral compounds in the field of clinical diagnostics and drug analysis.

Topics: Amines; Amino Acids; Arginine; Cadmium Compounds; Carbon; Fluorescent Dyes; Histidine; Quantum Dots; Reproducibility of Results; Tellurium

Since it is difficult for human eyes to distinguish between two identical colors with only <15% variation in brightness, mono-color fluorescent hydrogel microspheres have some limitations in the detection of lactate. Herein, we prepared novel dual-color fluorescent hydrogel microspheres, which can achieve hue transformation. Microspheres were prepared by introducing a fluorescent nanoparticle as the reference signal while CdTe QDs were used as the response signal. We used smartphones with image processing software to collect and analyze data. In this way, the signal of lactate was converted to RGB (red, green, and blue) values, which can be quantitatively read. Within 10 to 1500 μM, the R/G values of the microspheres had a linear relationship with the logarithm of the lactate concentration. Moreover, color cards for lactate detection were prepared, from which the color change and concentration of lactate could be easily read by the naked eye. It is worth mentioning that this method was successfully applied to screen patients with hyperlactatemia.

Topics: Cadmium Compounds; Fluorescent Dyes; Humans; Hydrogels; Lactic Acid; Microspheres; Quantum Dots; Smartphone; Spectrometry, Fluorescence; Tellurium

The composite of CdTe quantum dots (QDs) with ZIF-8 was elaborately designed and synthesized as an enzyme-free fluorescent probe for the sensitive determination of uric acid (UA), based on the fluorescence detection property of CdTe QDs and the signal amplification function of ZIF-8. The structure and feature of the composite were characterized with transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, and fluorescence spectrometry. With adding UA to the composite, the emission of CdTe QDs reduced due to the inner filter and dynamic quenching effects of UA, and the adsorption ability of ZIF-8 toward UA promoted the response signal of CdTe QDs. On this basis, UA was quantified by the composite in the concentration range 0.05 to 10 μM with excitation/emission wavelength at 287/615 nm, and the detection limit of the composite toward UA was 32 nM. The reproducibility of the composite for determining UA was further evaluated, and the relative standard deviations were below 10.2%. The composite also exhibited the merits of enzyme-free analysis such as low testing cost, short analysis time (1 min), and loose pH condition (application in whole physiological pH range, 5.0 - 8.0). The composite was applied to the determination of UA in human urine with recoveries of spiked samples in the range 99 to 113%.

Topics: Cadmium Compounds; Humans; Metal-Organic Frameworks; Quantum Dots; Reproducibility of Results; Tellurium; Uric Acid

Colloidal CdTe nanoplatelets featuring a large absorption coefficient and ultrafast tunable luminescence coupled with heavy-metal-based composition present themselves as highly desirable candidates for radiation detection technologies. Historically, however, these nanoplatelets have suffered from poor emission efficiency, hindering progress in exploring their technological potential. Here, we report the synthesis of CdTe nanoplatelets possessing a record emission efficiency of 9%. This enables us to investigate their fundamental photophysics using ultrafast transient absorption, temperature-controlled photoluminescence, and radioluminescence measurements, elucidating the origins of exciton- and defect-related phenomena under both optical and ionizing excitation. For the first time in CdTe nanoplatelets, we report the cumulative effects of a giant oscillator strength transition and exciton fine structure. Simultaneously, thermally stimulated luminescence measurements reveal the presence of both shallow and deep trap states and allow us to disclose the trapping and detrapping dynamics and their influence on the scintillation properties.

Topics: Cadmium Compounds; Luminescence; Quantum Dots; Tellurium

For the first time, a nanobiosensor was established for Sorghum mosaic virus (SrMV) detection. The biosensor consists of cadmium telluride quantum dots (CdTe QDs) conjugated to the specific antibody (Ab) against SrMV coat protein (CP) and carbon quantum dots (C QDs) labeled with SrMV coat protein. The formation of the fluorophore-quencher immunocomplex CdTe QDs-Ab+C QDs-CP led to a distinct decrease in the fluorescence intensity of CdTe QDs. Conversely, the emission intensity of CdTe QDs recovered upon the introduction of unlabeled CP. The developed biosensor showed a limit of detection of 44 nM in a linear range of 0.10-0.54 μM and exhibited the strongest fluorescence intensity (about 47,000 a.u.) at 552 nm. This strategy was applied to detect purified CP in plant sap successfully with a recovery rate between 93-103%. Moreover, the feasibility of the proposed method was further verified by the detection of field samples, and the results were consistent with an enzyme-linked immunosorbent assay (ELISA). Contrarily to ELISA, the proposed biosensor did not require excessive washing and incubation steps, thus the detection could be rapidly accomplished in a few minutes. The high sensitivity and short assay time of this designed biosensor demonstrated its potential application in situ and rapid detection. In addition, the fluorescence quenching of CdTe QDs was attributed to dynamic quenching according to the Stern-Volmer equation.

Topics: Biosensing Techniques; Cadmium Compounds; Early Diagnosis; Mosaic Viruses; Quantum Dots; Sorghum; Tellurium

The efficient preparation of ratiometric fluorescent molecularly imprinted polymer (MIP) microspheres that can directly and selectively optosense a herbicide (i.e., 2,4-dichlorophenoxyacetic acid, 2,4-D) in undiluted pure milk is described. The dual fluorescent MIP microparticles were readily obtained through grafting a green 4-nitrobenzo[c][1,2,5]oxadiazole (NBD)-labeled 2,4-D-MIP layer with hydrophilic polymer brushes onto the preformed uniform "living" red CdTe quantum dot (QD)-labeled SiO

Topics: 2,4-Dichlorophenoxyacetic Acid; Cadmium Compounds; Herbicides; Microspheres; Molecular Imprinting; Molecularly Imprinted Polymers; Quantum Dots; Silicon Dioxide; Tellurium

This work proposed ratiometric fluorescence capillary sensing system-integrated molecular imprinting with highly sensitive and selective detection for two biological indicators of Parkinson's disease (homovanillic acid (HVA) and Al

Topics: Cadmium Compounds; Environmental Biomarkers; Fluorescent Dyes; Humans; Limit of Detection; Molecular Imprinting; Parkinson Disease; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A magnetic molecularly imprinted probe (MMIP@QD) was synthesized by reverse microemulsion method using CdTe QDs, Fe

Topics: Cadmium Compounds; Magnetite Nanoparticles; Quantum Dots; Spectroscopy, Fourier Transform Infrared; Tellurium

Herein, a strategy combining colorimetry and inner filter effect (IFE)-based fluorometry was developed for multimode visualization of food dyes (FDs) using CdTe quantum-dots-doped fluorescent indicator papers as a sample-to-answer device. Colorimetry was straightforwardly achieved by FDs extraction through electrostatic interaction and hydrophobic effect while fluorometry was implemented by IFE-induced fluorescence quenching. RGB/gray-scale values of colorimetry and fluorometry were furtherly picked by a smartphone application and applied to reconstruct color information-based digital image analysis for both direct alignments and linear regression analysis. The apparent color and fluorescence of FDs-bound indicator papers, together with their digitized color information, showed a good mapping to FDs concentrations in the range of 0-0.5 mg/mL for Sunset Yellow, 0-0.2 mg/mL for Allura Red, and 0-0.08 mg/mL for Brilliant Blue. As a proof of concept, the dosages of these FDs in real beverages and simulated dye effluents were deduced and cross-validated by different visualization modes, and finally double-checked by instrumental techniques such as spectrometric methods, high-performance liquid chromatography (HPLC), and mass spectroscopy (MS). The above findings concluded that (i) IFE mechanism is generally applicable to build fluorometric systems and (ii) cross validation of different visualization modes can markedly improve detection accuracy, which may provide references for design and fabrication of novel "lab-on-paper" devices for visualization applications with high reliability.

Topics: Cadmium Compounds; Carbon; Colorimetry; Fluorescent Dyes; Fluorometry; Quantum Dots; Reproducibility of Results; Tellurium

Spectral micro-CT imaging with direct-detection energy discriminating photon counting detectors having small pixel size (< 100×100 µm

Topics: Animals; Cadmium Compounds; Mice; Phantoms, Imaging; Photons; Quantum Dots; Tellurium; X-Ray Microtomography

Bacterial contamination of water and food is a grave health concern rendering humans quite vulnerable to disease(s), and proving, at times, fatal too. Exploration of the novel diagnostic tools is, accordingly, highly called for to ensure rapid detection of the pathogenic bacteria, particularly Escherichia coli. The current manuscript, accordingly, reports the use of silane-functionalized glass matrices and antibody-conjugated cadmium telluride (CdTe) quantum dots (QDs) for efficient detection of E. coli. Synthesis of QDs (size: 5.4-6.8 nm) using mercaptopropionic acid (MPA) stabilizer yielded stable photoluminescence (∼62%), corroborating superior fluorescent characteristics. A test sample, when added to antibody-conjugated matrices, followed by antibody-conjugated CdTe-MPA QDs, formed a pathogen-antibody QDs complex. The latter, during confocal microscopy, demonstrated rapid detection of the selectively captured pathogenic bacteria (10 microorganism cells/10 μL) with enhanced sensitivity and specificity. The work, overall, encompasses establishment and design of an innovative detection platform in microbial diagnostics for rapid capturing of pathogens in water and food samples.

Topics: Bacteria; Biosensing Techniques; Cadmium Compounds; Escherichia coli; Humans; Quantum Dots; Tellurium; Water

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol-gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05-18.0 μM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2-106.4%, suggesting a potential application in food analysis.

Topics: Cadmium Compounds; Dibutyl Phthalate; Humans; Limit of Detection; Molecular Imprinting; Quantum Dots; Tellurium; Zeolites

Spectroscopic X-ray detectors (SXDs) are under development for X-ray imaging applications. Recent efforts to extend the detective quantum efficiency (DQE) to SXDs impose a barrier to experimentation and/or do not provide a task-independent measure of detector performance. The purpose of this article is to define a task-independent DQE for SXDs that can be measured using a modest extension of established DQE-metrology methods.. We defined a task-independent spectroscopic DQE and performed a simulation study to determine the relationship between the zero-frequency DQE and the ideal-observer signal-to-noise ratio (SNR) of low-frequency soft-tissue, bone, iodine, and gadolinium signals. In our simulations, we used calibrated models of the spatioenergetic response of cadmium telluride (CdTe) and cadmium-zinc-telluride (CdZnTe) SXDs. We also measured the zero-frequency DQE of a CdTe detector with two energy bins and of a CdZnTe detector with up to six energy bins for an RQA9 spectrum and compared with model predictions.. The spectroscopic DQE accounts for spectral distortions, energy-bin-dependent spatial resolution, interbin spatial noise correlations, and intrabin spatial noise correlations; it is mathematically equivalent to the squared SNR per unit fluence of the generalized least-squares estimate of the height of an X-ray impulse in a uniform noisy background. The zero-frequency DQE has a strong linear relationship with the ideal-observer SNR of low-frequency soft-tissue, bone, iodine, and gadolinium signals, and can be expressed in terms of the product of the quantum efficiency and a Swank noise factor that accounts for DQE degradation due to, for example, charge sharing (CS) and electronic noise. The spectroscopic Swank noise factor of the CdTe detector was measured to be 0.81. The spectroscopic DQE defined here is (1) task-independent, (2) can be measured using a modest extension of existing DQE-metrology methods, and (3) is predictive of the ideal-observer SNR of soft-tissue, bone, iodine, and gadolinium signals. For CT applications, the combination of CS and electronic noise in CdZnTe spectroscopic detectors will degrade the zero-frequency DQE by 10 %-20 % depending on the electronic noise level and pixel size.

Topics: Cadmium Compounds; Quantum Dots; Tellurium; X-Rays

The objective of this article is to introduce a simplified and swift method to satisfactorily estimate the half-value layers (HVL), quarter-value layer (QVL), and tenth-value layer (TVL) from the x-ray spectra emitted by any diagnostic radiology or kV radiotherapy x-ray tubes.. A CdTe x-ray and Gamma detector (X-123 CdTe, AmpTek Inc.) is used to measure the x-ray spectra at four different x-ray energies (low, mid, high energy x-rays) with different external filtering. The software "SpekCalc GUI" (Developed in McGill University, Montreal, Canada) is also used to obtain the simulated x-ray spectra. Both measured and simulated spectra are used to compute the HVL thicknesses of Aluminum by a mathematical method presented in this article. Next, the HVL thicknesses for corresponding tube potentials are also measured by calibrated ionization chamber and varying thicknesses of aluminum plates. Finally, the computed and measured HVL, QVL, and TVL thicknesses are compared to evaluate the efficacy of the presented method.. The results show acceptable concordance between computed and measured quantities. The disagreement rates between measured HVL and the values derived mathematically from the x-ray spectra are 10 to 90 micrometers of Aluminum at tube potentials of 31 kV to 120 kV. As it is shown, a negligible discrepancy is observed between the analytical estimation and the experimental assessments.. The HVL is an essential component in the evaluation of the quality of an x-ray beam. However, its measurement could occasionally be challenging, time-consuming, or uncertain due to some technical difficulties. Although the scope of this study is not to undermine the value of conventional and widely accepted practice to determine the HVL thickness, the introduced method provides the fast, more convenient, and comparably reliable technique to estimate the HVL, QVL, and TVL by employing the given x-ray spectrum.

Topics: Cadmium Compounds; Humans; Quantum Dots; Tellurium; X-Rays

Herein, novel rodlike CdTe@MPA-PDA particles based on polydopamine (PDA) loaded with CdTe quantum dots (QDs) capped with mercaptopropionic acid (CdTe@MPA QDs) with atypical chemical features are evaluated as a potential actuator for photothermal therapy and oxidative stress induction. Under mild conditions established for the safe and efficient use of lasers, temperature increases of 10.2 and 7.8 °C, photothermal conversion efficiencies of 37.7 and 26.2%, and specific absorption rates of 99 and 69 W/g were obtained for CdTe@MPA-PDA and traditional PDA particles in water, respectively. The particles were set to interact with the human breast adenocarcinoma cell line MDA-MB-231. A significant cellular uptake with the majority of particles colocalized into the lysosomes was obtained at a concentration of 100 μg/mL after 24 h. Additionally, CdTe@MPA-PDA and CdTe@MPA QDs showed significantly different internalization levels and loading kinetics profiles. For the first time, the thermal lens technique was used to demonstrate the stability of particle-like CdTe@MPA-PDA after heating at pH 7 and their migration within the heating region due to the thermodiffusion effect. However, under acidic pH-type lysosomes, a performance decrease in heating was observed, and the chemical feature of the particles was damaged as well. Besides, the internalized rodlike CdTe@MPA-PDA notably enhanced the induction of oxidative stress compared with PDA alone and CdTe@MPA QDs in MDA-MB-231 cells initiating apoptosis. Combining these effects suggests that after meticulous optimizations of the conditions, the CdTe@MPA-PDA particles could be used as a photothermal agent under mild conditions and short incubation time, allowing cytoplasmatic subcellular localization. On the other hand, the same particles act as cell killers by triggering reactive oxygen species after a longer incubation time and lysosomal subcellular localization due to the pH effect on the chemical morphology features of the CdTe@MPA-PDA particles.

Topics: Antineoplastic Agents; Apoptosis; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Humans; Indoles; Light; Oxidative Stress; Photosensitizing Agents; Polymers; Quantum Dots; Reactive Oxygen Species; Tellurium

We probed the "dark" state involved in the protein-quantum dot (QD) interaction using a relaxation-based solution nuclear magnetic resonance (NMR) approach. We examined the dynamics and exchange kinetics of the ubiquitin-CdTe model system, which undergoes a fast exchange in the transverse relaxation time scale. We applied the recently developed dark-state exchange saturation transfer (DEST), lifetime line broadening (Δ

Topics: Cadmium Compounds; Magnetic Resonance Spectroscopy; Nuclear Magnetic Resonance, Biomolecular; Quantum Dots; Tellurium

This work focuses on the synthesis of novel modified core-shell CdTe/CdS quantum dots (QDs) and develops as a fluorescence sensor for glucose determination. The (E)-2,2'-(4,4'-dioxo-2,2'-dithioxo-2H,2'H-[5,5'-bithiazolylidene]-3,3'(4H,4'H)-diyl)bis(3- mercaptopropanoic acid) (DTM) as a new derivative of thiazolidine was synthesized and characterized and used to surface-modification of CdTe/CdS QDs. DTM-capped CdTe/CdS QDs used to immobilization of glucose oxidase (GOD). The intensity fluorescence emission of the CdSe/CdS-DTM/GOD is highly sensitive to the concentration of H

Topics: Biocompatible Materials; Cadmium Compounds; Colloids; Enzymes, Immobilized; Fluorescent Dyes; Glucose; Glucose Oxidase; Molecular Structure; Quantum Dots; Sulfides; Surface Properties; Tellurium; Thiazolidines

Cadmium toxicity occurs where there is absorption and accumulation of cadmium ions (Cd

Topics: Animals; Biological Availability; Cadmium Chloride; Cadmium Compounds; Dose-Response Relationship, Drug; Female; Male; Rats; Rats, Wistar; Solubility; Tellurium; Tissue Distribution; Toxicokinetics

Imaging probes are an important consideration for any type of contrast agent-based imaging method. X-ray luminescence imaging (XLI) and x-ray luminescence computed tomography (XLCT) are both contrast agent-based imaging methods that employ x-ray excitable scintillating imaging probes that emit light to be measured for optical imaging. In this work, we compared the performance of several select imaging probes, both commercial and self-synthesized, for application in XLI/XLCT imaging. Commercially available cadmium telluride quantum dots (CdTe QDs) and europium-doped gadolinium oxysulfide (GOS:Eu) microphosphor as well as synthesized

Topics: Cadmium Compounds; Contrast Media; Erbium; Europium; Fluorides; Gadolinium; Image Processing, Computer-Assisted; Luminescence; Optical Imaging; Phantoms, Imaging; Quantum Dots; Tellurium; Tomography, X-Ray Computed

Cadmium telluride (CdTe) quantum dots (QDs) can be employed as imaging and drug delivery tools; however, the toxic effects and mechanisms of low-dose exposure are unclear. Therefore, this pioneering study focused on hepatic macrophages (Kupffer cells, KCs) and explored the potential damage process induced by exposure to low-dose CdTe QDs. In vivo results showed that both 2.5 μM/kg·bw and 10 μM/kg·bw could both activate KCs to cause liver injury, and produce inflammation by disturbing antioxidant levels. Abnormal liver function further verified the risks of low-dose exposure to CdTe QDs. The KC model demonstrated that low-dose CdTe QDs (0 nM, 5 nM and 50 nM) can be absorbed by cells and cause severe reactive oxygen species (ROS) production, oxidative stress, and inflammation. Additionally, the expression of NF-κB, caspase-1, and NLRP3 were decreased after pretreatment with ROS scavenging agent N-acetylcysteine (NAC, 5 mM pretreated for 2 h) and the NF-κB nuclear translocation inhibitor Dehydroxymethylepoxyquinomicin (DHMEQ, 10 μg/mL pretreatment for 4 h) respectively. The results indicate that the activation of the NF-κB pathway by ROS not only directly promotes the expression of inflammatory factors such as pro-IL-1β, TNF-α, and IL-6, but also mediates the assembly of NLRP3 by ROS activation of NF-κB pathway, which indirectly promotes the expression of NLRP3. Finally, a high-degree of overlap between the expression of the NF-κB and NLRP3 and the activated regions of KCs, further support the importance of KCs in inflammation induced by low-dose CdTe QDs.

Topics: Cadmium Compounds; Chemical and Drug Induced Liver Injury; Humans; Inflammasomes; NF-kappa B; NLR Family, Pyrin Domain-Containing 3 Protein; Quantum Dots; Reactive Oxygen Species; Tellurium

A dual recognition system with a fluorescence quenching of quantum dots (QDs) and specific recognition of molecularly imprinted polymer (MIP) for the detection of chloramphenicol (CAP) was constructed. MIP@SiO

Topics: Cadmium Compounds; Chloramphenicol; Fluorescence; Fluorometry; Hydrogen-Ion Concentration; Lakes; Limit of Detection; Microscopy, Electron, Transmission; Molecular Imprinting; Propylamines; Quantum Dots; Sensitivity and Specificity; Silanes; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Tellurium; Water Pollutants, Chemical

Topics: Apigenin; Cadmium Compounds; Fluorescence; L-Lactate Dehydrogenase; Quantum Dots; Tellurium

In this study, we investigated an experimental and Monte-Carlo computational characterization of self-assembled antennae built using CdTe colloidal quantum dots (QDs). These clusters provide efficient excitation of phycocyanine (PC) or phycobilisomes (PBSs). PBSs are light-harvesting complexes (LHCs) of cyanobacteria, made of several PC units, organized in disks and rods. Each PC contains three separate cofactors. Therefore, we analyzed variations in multi-donor and multi-acceptor systems. The self-assembled QD clusters were formed mostly by electrostatic interactions, possibly due to the introduction of a positive charge on an originally negatively charged nanoparticle surface. Our results suggest that PC may accept energy from multiple nanoparticles localized at a distance significantly longer than the Förster radius. The excitation transfers between particular nanoparticles with possible delocalization. The maximal energy transfer efficiency was obtained for the PC/PBS : QD ratio from 1 to 20 depending on the QD size. This cannot be fully explained using computational simulations; hence, we discussed the hypothesis and explained the observations. Our self-assembled systems may be considered for possible applications in artificial light-harvesting systems because absorption spectra of QDs are different from the absorption characteristics of PC/PBS. In addition, huge clusters of QDs may effectively increase the optical cross-section of so-created nanohybrids.

Topics: Cadmium Compounds; Colloids; Energy Transfer; Monte Carlo Method; Phycobilisomes; Phycocyanin; Quantum Dots; Tellurium

Herein, a universal fluorescent biosensor was developed for detecting Mycobacterium Tuberculosis (MTB) specific insertion sequence IS6110 gene fragment based on Förster resonance energy transfer (FRET) strategy. CdTe quantum dots (QDs), with excellent luminous performance, were used to label single-stranded DNA (ssDNA) as fluorescence donor (QDs-DNA), in which the ssDNA was complementary to the IS6110 gene fragment. A new type of two-dimensional metal-organic framework (Cu-TCPP) was served as an acceptor. The Cu-TCPP exhibited a higher affinity towards ssDNA than double-stranded DNA (dsDNA). In the absence of targets, the fluorescence of QDs-DNA was quenched - due to the π-π stacking interactions between Cu-TCPP and ssDNA. Otherwise, QDs-DNA hybridized with the target to form a double helix and the fluorescence maintained in a target-concentration dependent manner. Excess QDs-DNA would be quenched and produced negligible background signal. The fluorescent sensor possessed a linear range from 0.05 nM to 1.0 nM with a low detection limit of 35 pM. Furthermore, we successfully applied this biosensing system to detect clinical sputum samples. This method displayed high sensitivity, specificity and great potentials in the early diagnosis of Tuberculosis.

Topics: Biosensing Techniques; Cadmium Compounds; DNA Probes; Fluorescence Resonance Energy Transfer; Metal-Organic Frameworks; Mycobacterium tuberculosis; Quantum Dots; Tellurium

We are reporting on the impact of air annealing temperatures on the physicochemical properties of electrochemically synthesized cadmium selenium telluride (CdSe

Topics: Cadmium Compounds; Selenium Compounds; Solar System; Tellurium; Temperature

Topics: Cadmium Compounds; Gold; Metal Nanoparticles; Optical Imaging; Quantum Dots; Tellurium; X-Rays

Utilizing fluorescence spectroscopy, non-covalent and covalent interactions of L-cys@CdTe quantum dots to bovine serum albumin (BSA), cytochrome c and trypsin were investigated. L-cys@CdTe QDs with the emission maximum at 530 nm and an average diameter of 2.6 nm were synthesized in the aqueous medium. Formaldehyde, N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) with N-hydroxysuccinimide (NHS), and glutaraldehyde was applied as cross-linkers. In the case of both electrostatic and covalent strategies PARAFAC, as a powerful multi-way chemometrics technique, was utilized to analyze fluorescence excitation-emission (EEM) spectra. For non-covalent and covalent bonding, two and three significant components composed the PARAFAC models. Resolved EEM shows that in the presence of formaldehyde, a new component with an emission peak similar to BSA was obtained. Using EDC-NHS cross-linker, the fluorescence peak of the newly formed component was in a distinct wavelength with similar emission intensity, compared to L-cys@CdTe QDs and BSA. Employing glutaraldehyde, a distinguished component was easily detected at emission wavelengths higher than that of L-cys@CdTe QDs and proteins. It was concluded that the choice of cross-linker is a critical step to create different emission spectra when dealing with nano-bio-conjugations. This study shows that glutaraldehyde cross-linker leads to increase sensitivity, selectivity, and accuracy of protein analysis.

Topics: Cadmium Compounds; Cytochromes c; Quantum Dots; Serum Albumin, Bovine; Spectrometry, Fluorescence; Static Electricity; Tellurium; Trypsin

The quality of tea is influenced by numerous factors, especially l-theanine, which is one of the important markers used to evaluate the sweetness and freshness of tea. Sensitive, rapid, and accurate detection of l-theanine is therefore useful to identify the grade and quality of tea.. A high-sensitivity, paper-based fluorescent sensor combined with chemometrics was established to detect l-theanine in tea water based on CdTe quantum dots / corn carbon dots and nano tetra pyridel-porphine zinc (ZnTPyP). To verify the reliability of this method, fluorescence spectra and fluorescence-visualized paper-based sensors were compared. The fluorescence spectrum method demonstrated a linear range of 1 to 10 000 nmol L. This fluorescence-visualized paper-based sensor, combined with chemometrics, could be applied efficiently to the practical analysis of tea water samples, which provides a new idea to ensure the flavor and quality of tea. © 2020 Society of Chemical Industry.

Topics: Cadmium Compounds; Fluorescence; Food Analysis; Food Quality; Limit of Detection; Luminescent Measurements; Porphyrins; Quantum Dots; Tea; Tellurium; Zea mays

In this study, a novel, simple and sensitive ratiometric fluorescence method is presented for the detection of very low quantities of the carbaryl in Iranian apple using cadmium telluride quantum dots (CdTe QDs) nanoprobe. The principle of the proposed strategy relies on the rapid hydrolysis of the carbaryl under an alkaline condition and production of the 1-naphthol with a blue emission at 470 nm. Besides, using the CdTe QDs with a yellow emission at 580 nm, as a reference, improves the visual tracking of carbaryl through changes in color tonality. The herein described methodology is applied for enzyme-free visual detection of carbaryl with satisfactory results in the presence of other common pesticides in Iranian apple sample. Additionally, the calculated limit of detection (LOD) of 0.12 ng mL

Topics: Cadmium Compounds; Carbaryl; Fluorescence; Insecticides; Iran; Malus; Quantum Dots; Spectrometry, Fluorescence; Tellurium

CdTe quantum dots (CdTe QD) have been produced at different times of synthesis (1, 2, and 4 h) using thiols as capping agents: mercaptopropionic acid (MPA), mercaptosuccinic acid (MSA) and N-acetyl-l-cysteine (NAC) using water as a solvent. The produced CdTe QD were characterized by UV-vis and photoluminescence (PL) spectroscopy and showed a relationship among reflux time, size, and spectroscopic properties. CdTe QD were shown to interact with thimerosal (TM), an organic mercury compound, and the PL intensity was effectively quenched, characterizing an ON-OFF process. However, the NAC capped CdTe (CdTe-NAC) at 1 h presented the best sensitivity for TM determination. Under optimized conditions, a linear range from 0.1 to 1.0 μg mL

Topics: Cadmium Compounds; Fluorescent Dyes; Quantum Dots; Sulfhydryl Compounds; Tellurium; Thimerosal; Vaccines

Light-emitting diodes (LED) based on silicon platforms and CdTe quantum dots (QDs) are an important area of research. Due to poor charge balance in QD layers, reduced graphene oxide (RGO) was introduced between the P-Si substrate and CdTe QDs. To further improve the performance of the QDs-LED, Au nanorods (NRs) were incorporated into the hole transport layer. A finite-difference time-domain simulation was used to discuss theoretically the influence of RGO and Au NRs on the LED performance, and investigate the influence of substrate on the localized surface plasmon resonance (LSPR) coupling wavelength. Simulated results demonstrated that the LSPR peaks for Au NRs red shifted with increase in substrate refractive index, and the electric field along the x-y plane was mostly concentrated near the interface. RGO incorporation enhanced the emission of the QDs-LED. This may be attributed to improvement in conductivity and hole mobility in the hole transport layer and reduction in the energy barrier for injection of holes. After introduction of Au NRs, there was a significant enhancement in emission, and light extraction efficiency was enhanced about 10-fold.

Topics: Cadmium Compounds; Nanotubes; Quantum Dots; Tellurium

Proficient fluorescent-characteristics, cytotoxicity-behavior and antimicrobial-activity of near-infrared-emitting (NIR) CdTe quantum dots (QDs) were studied sumptuously as these QDs are having an excellence in deep-tissue dissemination of light. These, NIR-emitting QDs were synthesized using aqueous method, utilizing 3-mercaptopropionic-acid (3-MPA) as a stabilizer; it controls leakage of Cd and Te ions from CdTe QDs. However, encapsulation by polymers also prevents the same by seizing toxic consequence of prepared QDs which was confirmed from cytotoxicity studies. Therefore, easy modification according to biological environment of these encapsulated CdTe QDs can serve in bio imaging and distribution. Antimicrobial study investigated the toxic effects of QDs against bacterial strains and support cytotoxicity studies and showing maximum 26 mm zone of inhibition against bacterial strain. These, NIR fluorescent QDs possess many attractive optical properties over the standard fluorescent probes (organic dyes) and can replace these dyes, as there is no specific dye which works in NIR range.

Topics: Cadmium Compounds; Fluorescent Dyes; Quantum Dots; Tellurium; Water

Fluorescent semiconductor nanoparticles or quantum dots (QDs) have excellent properties as photosensitizers in photodynamic therapy. This is mainly a consequence of their nanometric size and the generation of light-activated redox species. In previous works, we have reported the low-cost biomimetic synthesis of glutathione (GSH) capped QDs (CdTe-GSH QDs) with high biocompatibility. However, no studies have been performed to determine their phototoxic effect. The aim of this work was to characterize the light-induced toxicity of green (QDs. Photodegradation and reduction power of biomimetic QDs was determined to analyse their potential for radical generation. Escherichia coli cells were exposed to photoactivated QDs and viability was evaluated at different times. High toxicity was determined in E. coli cells exposed to photoactivated QDs, particularly QDs. Obtained results indicate that light exposure increases the toxicity of biomimetic QDs on E. coli cells. The mechanism of bacterial phototoxicity of biomimetic CdTe-GSH QDs is mostly associated with ROS generation.. The results presented establish biomimetic CdTe-GSH QDs as a promising cost-effective alternative against microbial infections, particularly QDs

Topics: Anti-Bacterial Agents; Biomimetic Materials; Biomimetics; Cadmium; Cadmium Compounds; Escherichia coli; Microbial Viability; Mutation; Oxidation-Reduction; Oxidative Stress; Photosensitizing Agents; Quantum Dots; Reactive Oxygen Species; Tellurium

Bioorthogonal chemistry has been considered as a powerful tool for biomolecule labeling due to its site specificity, moderate reaction conditions, high yield, and simple post-treatment. Covalent coupling is commonly used to modify quantum dots (QDs) with bioorthogonal functional group (azide or cycloalkyne), but it has a negative effect in the decrease of QDs' quantum yield and stability and increase of QDs' hydrodynamic diameter. To overcome these disadvantages, we propose a novel method for the preparation of two kinds of clickable QDs by the strong interaction of -SH with metal ions. One system involves azide-DNA-functionalized QDs, which are used for bioconjugation with dibenzocyclooctyne (DBCO)-modified glucose oxidase (GOx) to form a GOx-QDs complex. After bioconjugation, the stability of QDs was improved, and the activity of GOx was also enhanced. The GOx-QDs complex was used for rapid detection of blood glucose by spectroscopy, naked eye, and paper-based analytical devices. The second system involves DBCO-DNA-functionalized QDs, which are used for an in situ bioorthogonal labeling of HeLa cells through metabolic oligosaccharide engineering. Therefore, these clickable QDs based on DNA functionalization can be applied for rapid and effective labeling of biomolecules of interest.

Topics: Biosensing Techniques; Blood Glucose; Cadmium Compounds; Diabetes Mellitus; Glucose; HeLa Cells; Humans; Quantum Dots; Tellurium; Zinc

Topics: Cadmium Compounds; Cell Line; Humans; Liver Neoplasms; Mitochondrial Dynamics; Mitophagy; Quantum Dots; Tellurium

A smartphone-combined dual-emission ratiometric fluorescence probe for specifically and visibly detecting cephalexin was first designed. In the probe, blue-emitting fluorescent carbon dots (CDs) was synthesized and covered with a layer of silica spacer. Red-emitting fluorescent CdTe QDs (r-QDs) was grafted onto the silica nanospheres as an analytical probe. Then, the cephalexin antibody was covalent grafted to the ratio sensor to increase the selectivity. The ratio of fluorescence intensity (FL) of r-QDs and CDs was quenched with the increasing concentration of cephalexin. The detection method has good linear response in the range of 1-500 μM and the detection limit was 0.7 μM. Then portable device based on smartphone detection was constructed according to the color change under UV lamp. The detection image was obtained through the smartphone camera, and the color picker APP installed in the smartphone captured the RGB value of the image. In addition, this method was also used to determine the amount of cephalexin in milk samples with recovery of 94.1%-102.2%. These results showed that it was a portable, simple and visible method to detect cephalexin in food analysis and environmental monitoring.

Topics: Cadmium Compounds; Cephalexin; Fluorescent Dyes; Quantum Dots; Smartphone; Tellurium

Organic dyes are typically applied as photosensitizers in photoelectrochemical (PEC) cells but have not been reported in polarity-reversal-mode PEC sensors with excellent sensitivity and accuracy. Herein, an elegant and robust PEC biosensor for carcinoembryonic antigen (CEA) has been designed by photocurrent polarity switching of CdTe quantum dots (QDs), which is obtained by embedding methylene blue (MB) into amplified double-stranded DNA (dsDNA) anchored to the superparamagnetic Fe

Topics: Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; DNA; Electrochemical Techniques; Ferric Compounds; Humans; Magnetic Phenomena; Methylene Blue; Particle Size; Photochemical Processes; Quantum Dots; Silicon Dioxide; Surface Properties; Tellurium

Topics: Animals; Cadmium Compounds; Caffeine; Cattle; Colorimetry; Humans; Limit of Detection; Metalloporphyrins; Paper; Quantum Dots; Tea; Tellurium; Water; Zinc Compounds

In this work, we continue our study of a new method for the detection of ionizing radiation with the potential for a dramatic improvement in coincidence time resolution (CTR) for time-of-flight positron emission tomography (ToF-PET) using the modulation of a material's optical properties instead of the scintillation mechanism. Our previous work has shown that for non-scintillation materials such as bismuth silicon oxide (BSO) and cadmium telluride (CdTe), their refractive index can be modulated by annihilation photon interactions. The ultrafast nature of this process however remains unexplored. The ionizing radiation-induced charge carriers alter the local band structure in these materials, thus changing the complex refractive index. This mechanism is routinely used at the linac coherent light source (LCLS) facility of the SLAC National Accelerator Laboratory to measure x-ray pulse arrival times with femtosecond scale resolution for photon energies between 0.5 and 10 keV. The method described here follows that example by using a frequency chirped visible continuum pulse to provide a monotonic wavelength-to-time mapping by which one can measure the time-dependent refractive index modulation. In addition, we describe an interference-based measurement setup that allows for significantly improved sensitivity while preserving a timing precision of approximately 10 fs (σ) when measuring the arrival time of below 10 keV x-ray pulses with yttrium aluminum garnet (YAG) crystal. The method is presented in the context of ToF-PET application with further discussions on the potential CTR achievable if a similar detection concept is adopted for detecting 511 keV photons. Semi-empirical analysis indicates that the predicted CTR achievable is on the order of 1 ps (FWHM).

Topics: Bismuth; Cadmium Compounds; Optical Phenomena; Photons; Quantum Dots; Tellurium; Tomography, X-Ray Computed

Topics: Animals; Brachyura; Cadmium Compounds; Female; Glutathione; Lethal Dose 50; Lipid Peroxides; Male; Ovary; Quantum Dots; Reproduction; Tellurium; Testis

Near-infrared electrochemiluminescence (NIR ECL) luminophores are strongly anticipated in ECL bioimaging and spectrum-resolved multiplexing assays. Herein, bovine serum albumin-stabilized Ag nanoclusters (BSA-Ag NCs) are demonstrated promising NIR ECL performance, exhibiting strong anodic ECL spectrum peak at 904 nm in aqueous medium. The ECL intensity of BSA-Ag NCs-triethanolamine system was enhanced 3.2 times by adding TiO

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Immunoassay; Luminescent Measurements; Nanotubes, Carbon; Quantum Dots; Serum Albumin, Bovine; Silver; Tellurium

Drug-resistant bacterial infections are a growing cause of illness and death globally. Current methods of treatment are not only proving less effective but also perpetuate evolution of new resistance. Here we propose, through an

Topics: Animals; Anti-Bacterial Agents; Cadmium Compounds; Mice; Models, Animal; Quantum Dots; Tellurium

Paraquat is one of the most toxic materials widely applied in agriculture in most countries. In the present study, a simple, innovative and inexpensive nano biosensor which is based on a thioglycolic acid (TGA) - CdTe@CdS core-shell nanocrystals (NCs) to detect paraquat, is suggested. The NCs based biosensor shows a linear working range of 10-100 nM, and limited detection of 3.5 nM. The proposed sensor that has been well used for the detection and determination of paraquat in natural water samples is collected from corn field and a canal located near to the corn field yielding recoveries as high as 98%. According to our findings, the developed biosensor shows reproducibility and high sensitivity to determine paraquat in natural water samples in which the amount of paraquat has low levels. The suggested method is efficiently applied to paraquat determination in the samples of natural water that are collected from a tap water and a canal located near to the cornfield.

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescent Dyes; Hydrogen-Ion Concentration; Nanoparticles; Paraquat; Sulfates; Tellurium; Thioglycolates; Water Pollutants, Chemical

Optical property modulation induced by ionizing radiation is a promising approach for ultra-fast, lower time jitter detection of photon arrival time. If successful, this method can be utilized in time-of-flight positron emission tomography to achieve a coincidence time resolution approaching 10 ps. In this work, the optical property modulation based method is further developed with focus on a detection setup based on two crossed polarizers. Previous work demonstrated that such an optical setup could be utilized in radiation detection, though its detection sensitivity needed improvement. This work investigates the angle between polarizers and electric field distribution within the detection crystal to understand and improve the detection sensitivity of an optical polarization modulation based method. For this work, cadmium telluride (CdTe) was studied as the detector crystal . The 'magic' angle (i.e. optimal working angle) of the two crossed polarizers based optical setup with CdTe were explored theoretically and experimentally. The experimental results show that the detection sensitivity could be improved by around 10% by determining the appropriate 'magic' angle. We then studied the dependence of detection sensitivity on electric field distribution as well as on the bias voltage across the detector crystal using CdTe crystals. The experimental results show that a smaller electrode on the detector crystal, or a more concentrated electric field distribution could improve detection sensitivity. For CdTe, a detector crystal sample with 2.5 mm × 2.5 mm square electrode has twice the detection sensitivity of a detector crystal with 5 mm × 5 mm square electrode. Increasing the bias voltage before saturation for CdTe could further enhance the modulation strength and thus, the sensitivity. Our investigations demonstrated that by determining the proper working angle of polarizers and bias electrical distribution to the detector, we could improve the sensitivity of the proposed optical setup.

Topics: Cadmium Compounds; Image Interpretation, Computer-Assisted; Photons; Positron-Emission Tomography; Quantum Dots; Radiation, Ionizing; Radiometry; Tellurium

As a special carrier of traditional Chinese culture, baijiu is rich in terms of types and ingredients. Its quality analysis and control are always important and complex issues that urgently need reliable evaluation methods. In this study, four different modified CdTe quantum dots (QDs) were used to characterize their sensing performance to various baijiu. A sensor array was then constructed through the complementary properties of differential fluorescence signals. To achieve an accurate and rapid evaluation of different baijiu types, a linear discriminant analysis (LDA) was introduced to extract and process spectral information. And the array was able to distinguish commercial baijiu samples with different aroma-types, brands, qualities and storage years with a recognition rate of 100%. In addition, according to the heat map, the organic acids in baijiu were shown to be the main components causing the fluorescence change through electron transfer (hydrogen bond) and resonance energy transfer among QDs and acids. Furthermore, using the partial least squares regression (PLSR) model, five representative organic acids were accurately quantified with a quantitative range of 10 μmol/L-80 μmol/L with a high selectivity. This QDs fluorescence sensing strategy provides an accurate, simple, and fast baijiu sensing method, which provides a potential use for on-line baijiu monitoring.

Topics: Cadmium Compounds; China; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Herein, an innovative ratiometric fluorescence (FL) aptasensor was successfully fabricated for the accurate analysis of zearalenone (ZEN) in corn and barley flour. The ZEN aptamer-modified nitrogen doped graphene quantum dots (NGQDs-apt) and silica sphere-encapsulated cadmium telluride quantum dots (CdTe QDs@SiO

Topics: Aptamers, Nucleotide; Cadmium Compounds; Crops, Agricultural; Edible Grain; Flour; Fluorescence; Graphite; Limit of Detection; Mitoxantrone; Quantum Dots; Silicon Dioxide; Tellurium; Zearalenone

Topics: Biosensing Techniques; Cadmium Compounds; Crops, Agricultural; Hydrogen-Ion Concentration; Organophosphorus Compounds; Pesticides; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Cadmium telluride (CdTe) nanoparticles (NPs) are known for their unique physical and chemical properties. NP synthesis via a size-controlled procedure has become an intriguing research topic because NPs exhibit novel optical and physical properties depending on their size. Their sizes and properties can vary depending on the types and concentrations of stabilizers, which are bound to the surface of the NPs and protect the NPs from aggregation. In this study, we synthesized CdTe NPs stabilized by thioglycolic acid (TGA), 1-thioglycerol (TGC), and L-cysteine (L-C). The ratio of stabilizer to Cd

Topics: Cadmium Compounds; Cysteine; Glycerol; Nanoparticles; Quantum Dots; Tellurium; Thioglycolates; X-Ray Diffraction

A fluorescent probe has been developed for tetra bromo bisphenol A (TBBPA) detection based on molecularly imprinted polymers (MIPs) combined with wrinkled silica nanoparticles (WSNs) and CdTe quantum dot (QD) hybrid particles. The WSNs with large pore sizes were employed as a structural support platform for QD embedding, and MIPs were synthesized on the surface of QD-embedded WSNs. The synthetic procedure was characterized using transmission electron microscopy, Brunauer-Emmett-Teller measurements, X-ray photoelectron spectrometry, Fourier transform infrared spectroscopy, and zeta potential analysis. The MIP-capped wrinkled silica-QD hybrid particles (WSNs-QDs-MIPs) possessed an adsorption capacity of 96.5 mg g

Topics: Cadmium Compounds; Fluorescent Dyes; Limit of Detection; Molecularly Imprinted Polymers; Polybrominated Biphenyls; Quantum Dots; Reproducibility of Results; Silicon Dioxide; Solid Waste; Spectrometry, Fluorescence; Tellurium

Deoxynivalenol (DON) is considered a mycotoxin that is toxic to the agricultural environment and human body. It is necessary to study the pathophysiological mechanism of DON toxicity at the cellular level. Cytochrome c (Cyt c), as an important biomarker of DON-induced apoptosis that may lead to a bipartite 'point-of-no return' event, is of great significance to be detected using cell imaging. Herein, we synthesized a DON-deactivated emission fluorescent probe, the molecularly imprinted polymer-coated quantum dots (CdTe@MIP), for monitoring the Cyt c level with a photoinduced electron transfer strategy. The CdTe@MIP probe can be easily loaded into cells and perform well due to its great sensitivity and selectivity and its fluorescence was gradually quenched with the increasing concentration (0-10 μM) and incubation time (0-7.5 h) of DON. Cell imaging results of apoptosis induced by DON was consistent with that of the cell counting kit-8 assay and flow cytometry technique. The developed method can be used to monitor DON-induced apoptosis and provide an early-warning system for the contaminant toxicity.

Topics: Apoptosis; Cadmium Compounds; Cytochromes c; Electrons; Fluorescent Dyes; Humans; Quantum Dots; Tellurium; Trichothecenes

This work reports an edge enhancing effect experimentally observed in cadmium telluride (CdTe)-based photon counting detector (PCD) systems operated under the charge summing (CS) mode and irradiated by high-flux x-rays. Experimental measurements of the edge spread functions (ESFs) of a PCD system (100

Topics: Cadmium Compounds; Communication; Monte Carlo Method; Photons; Quantum Dots; Tellurium

In the present study, an easy to use field-deployable methodology was developed for onsite detection of pesticidal crystal protein Cry2Ab from transgenic cotton crops to reduce seed adulteration. Anti Cry2Ab IgG and IgY antibodies were developed against recombinant Cry2Ab protein in New Zealand white rabbits and in white leg horn chickens, respectively. Carboxyl-functionalized CdTe quantum dots (QDs) were used as revealing probes, and nitrocellulose paper was used as an assay matrix. Recombinant Cry2Ab was generated in the lab and used for immunization of chicken and rabbits. After successful immunization and attaining the desired titer values (1:32 000 for IgY and 1:64 000 for IgG), eggs and hyperimmune sera were collected. Anti Cry2Ab IgY was purified as per the standardized protocols, and anti Cry2Ab IgG was purified using protein A affinity chromatography. Sensitivity of the generated antibodies was examined using indirect ELISA methods against recombinant Cr2Ab protein. Specificity evaluation was carried out against other Cry proteins including Cry2Ab, Cry4b, Cry4a, Cry1Ec, and Cry1Ac. Functionalized CdTe QDs were characterized for structure and shape as well as fluorescence properties using standard laboratory techniques. A field-deployable paper-based detection methodology was developed where IgG acted as the capturing antibody and IgY-linked CdTe QDs were used as revealing probes. The limit of detection (LOD) and quantification (LOQ) were found to be 2.91 ng/mL and 9.71 ng/mL, respectively. The effect of matrix interference was assessed on the different plant crude extracts of cottonseed materials.

Topics: Animals; Bacillus thuringiensis Toxins; Bacterial Proteins; Cadmium Compounds; Chickens; Cottonseed Oil; Endotoxins; Hemolysin Proteins; Immunoglobulins; Insecticides; Quantum Dots; Rabbits; Tellurium

This research study focused on exploring the impact of resilience on COVID-19 phobia (C19P) among individuals from different nations including a cluster of European countries, India, Indonesia, Pakistan and the United States of America (USA).. We recruited research participants via disseminating an electronic survey on Facebook Messenger (FM) that included 812 participants. The electronic survey assessed unidentifiable demographic information, the COVID-19 Phobia Scale (C19P-S; Arpaci et al., 2020) and the Brief Resilience Scale (BRS; Smith et al, 2008).. We concluded that the higher the resilience level, the lower the level of C19P. The level of resilience was highest in the USA, followed by Europe, Pakistan, India and Indonesia. Age affected the resilience level positively and resilience differed based on marital status, education levels, and professional status but not between genders. Implications are offered for effective counselling interventions during this COVID-19 pandemic and the aftermath.

Topics: Algorithms; Animals; Anti-Bacterial Agents; Aortic Valve; Aortic Valve Stenosis; Azo Compounds; Bioprosthesis; Cadmium Compounds; Catalysis; CD8-Positive T-Lymphocytes; Cockroaches; COVID-19; Cytokines; Deep Learning; Fluorescence; Fluorescent Dyes; Graphite; Heart Valve Prosthesis; Heart Valve Prosthesis Implantation; Humans; Insecticides; Interleukin-10; Interleukin-6; Lakes; Limit of Detection; Microwaves; Nanostructures; Nanotubes, Carbon; Neonicotinoids; Neural Networks, Computer; Neurons; Nitrogen Compounds; Oxygen; Peptides; Periplaneta; Propensity Score; Prosthesis Design; Proteome; Quantum Dots; Receptors, Nicotinic; Retrospective Studies; SARS-CoV-2; Spectrometry, Fluorescence; Sulfadimethoxine; Sulfides; Tandem Mass Spectrometry; Tellurium; Treatment Outcome; Wastewater; Water Pollutants, Chemical; Zinc Compounds

Photocatalytic systems comprising a hydrogenase-type catalyst and CdX (X = S, Se, Te) chalcogenide quantum dot (QD) photosensitizers show extraordinary hydrogen production rates under visible light excitation. What remains unknown is the mechanism of energy conversion in these systems. Here, we have explored this question by comparing the performance of two QD sensitizers, CdSe and CdTe, in photocatalytic systems featuring aqueous suspensions of a [Fe

Topics: Biomimetics; Cadmium Compounds; Hydrogen; Hydrogenase; Photosensitizing Agents; Quantum Dots; Selenium Compounds; Tellurium

The extraction of bitumen from oil sands produces fluid fine tailings (FFT) consisting mainly of water, sands, clay, and residual bitumen. Generally, devices with radioactive sources are used to measure the variation of FFT density or solids concentration inline, but to date there is no suitable device for in situ monitoring in tailings storage facilities such as large tailings ponds. In this study, an alternative method using high-resolution spectrometry based on a low radiation intensity source and a cadmium telluride (CdTe) detector was used to measure the solids content in tailings samples based on X-ray attenuation. The radiation source used in the experiment was a 1 μCi

Topics: Cadmium Compounds; Oil and Gas Fields; Quantum Dots; Tellurium; X-Rays

The fluorescent properties of cadmium telluride (CdTe) containing quantum dots (QDs) have led to novel products and applications in the ink and pigment industry. The toxic effects of the emissions associated to the use of printing ink containing CdTe QDs might differ from those of conventional formulations which do not integrate nanoparticles, as CdTe QDs might be emitted. Within this work, the airborne emissions of a water-soluble fluorescent ink containing polyethylene glycol (PEG)-coated CdTe QDs of 3-5 nm diameter have been characterized and studied under controlled conditions during household inkjet printing in a scenario simulating the use phase. Subsequently, the cytotoxicological potential of atomized CdTe QDs ink in an acute exposure regimen simulating an accidental, worse-case scenario has been evaluated in vitro at the air-liquid interface (ALI) using the pulmonary cell line BEAS-2B. Endpoints screened included cell viability, oxidative stress and inflammatory effects. We have observed that CdTe QDs ink at 54.7 ng/mL decreased cell viability by 25.6 % when compared with clean air after 1h of exposure; a concentration about 65 times higher was needed to observe a similar effect in submerged conditions. However, we did not observe oxidative stress or inflammatory effects. The present study integrates the development of scenarios simulating the use phase of nano-additivated inks and the direct cell exposure for in vitro effects assessment, thus implementing a life-cycle oriented approach in the assessment of the toxicity of CdTe QDs.

Topics: Aerosols; Bronchi; Cadmium Compounds; Cell Line; Cell Survival; Epithelial Cells; Fluorescence; Humans; Inflammation Mediators; Inhalation Exposure; Ink; Oxidative Stress; Printing; Quantum Dots; Risk Assessment; Tellurium

Herein, a zirconium metal organic framework (ZrMOF) based lateral flow assay (LFA) is described for the qualitative analysis of early acute myocardial infarction (AMI) biomarkers including heart-type fatty acid binding protein (h-FABP) and cardiac troponin (cTnT). ZrMOF@CdTe nanoparticles (NPs) are synthesized by a simple hydrothermal method. By changing the hydrothermal reaction time, ZrMOF@CdTe NPs with different fluorescent colours can be obtained. They can emit different colours of fluorescence under the excitation of a single wavelength, which makes them suitable for multiplexed lateral flow assays (mLFA). The visual limit of detection of the ZrMOF@CdTe-based LFA for the h-FABP antigen is 1 μg L-1. The analysis can be completed within 8 min and has the advantages of being easy to operate and visual detection. A serum sample collected from patients is successfully detected using this LFA. This assay is widely applicable and simple, has strong anti-interference ability, and is cost-effective and can provide basic information for later treatment.

Topics: Biomarkers; Cadmium Compounds; Fatty Acid-Binding Proteins; Humans; Metal-Organic Frameworks; Quantum Dots; Tellurium; Troponin T

Detailed visualization of bone microarchitecture is essential for assessment of wrist fractures in computed tomography (CT). This study aims to evaluate the imaging performance of a CT system with clinical cadmium telluride-based photon-counting detector (PCD-CT) compared with a third-generation dual-source CT scanner with energy-integrating detector technology (EID-CT).. Both CT systems were used for the examination of 8 cadaveric wrists with radiation dose equivalent scan protocols (low-/standard-/full-dose imaging: CTDIvol = 1.50/5.80/8.67 mGy). All wrists were scanned with 2 different operating modes of the photon-counting CT (standard-resolution and ultra-high-resolution). After reformatting with comparable reconstruction parameters and convolution kernels, subjective evaluation of image quality was performed by 3 radiologists on a 7-point scale. For estimation of interrater reliability, we report the intraclass correlation coefficient (absolute agreement, 2-way random-effects model). Signal-to-noise and contrast-to-noise ratios were calculated to provide semiquantitative assessment of image quality.. Subjective image quality of standard-dose PCD-CT examinations in ultra-high-resolution mode was superior compared with full-dose PCD-CT in standard-resolution mode (P = 0.016) and full-dose EID-CT (P = 0.040). No difference was ascertained between low-dose PCD-CT in ultra-high-resolution mode and standard-dose scans with either PCD-CT in standard-resolution mode (P = 0.108) or EID-CT (P = 0.470). Observer evaluation of standard-resolution PCD-CT and EID-CT delivered similar results in full- and standard-dose scans (P = 0.248/0.509). Intraclass correlation coefficient was 0.876 (95% confidence interval, 0.744-0.925; P < 0.001), indicating good reliability. Between dose equivalent studies, signal-to-noise and contrast-to-noise ratios were substantially higher in photon-counting CT examinations (all P's < 0.001).. Superior visualization of fine anatomy is feasible with the clinical photon-counting CT system in cadaveric wrist scans. The ultra-high-resolution scan mode suggests potential for considerable dose reduction over energy-integrating dual-source CT.

Topics: Cadaver; Cadmium Compounds; Humans; Phantoms, Imaging; Photons; Reproducibility of Results; Tellurium; Tomography, X-Ray Computed; Wrist

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Humans; Immunoassay; Limit of Detection; Luminescent Measurements; Metal Nanoparticles; Quantum Dots; Serum Albumin, Human; Silicon Dioxide; Tellurium

A sensitive anodic near-infrared electrochemiluminescence (ECL) immunosensor for the detection of tetracycline, based on Cu-doped CdTe quantum dots, was fabricated for the first time in this work. We have synthesized Cu-doped CdTe quantum dots by co-precipitation. The emission spectrum of the Cu-doped CdTe quantum dots could reach the near-infrared region at 730 nm in a short reflux time. More importantly, the ECL intensity of the CdTe quantum dots was enhanced by 2 fold after Cu element doping, which was attributed to the Cu d-orbital mixed with the conduction band and valence band of the host CdTe quantum dots. Inspired by the strong anodic ECL intensity of Cu-doped CdTe quantum dots, the anodic near infrared ECL sensor was constructed to detect tetracycline by competitive immunoassay. The detection range of the developed biosensor was 0.01-10 ng mL-1 and the detection limit was 0.0030 ng mL-1. In addition, the biosensor showed outstanding selectivity, long-term stability and high reproducibility, which has great potential in the field of analysis and detection.

Topics: Biosensing Techniques; Cadmium Compounds; Immunoassay; Quantum Dots; Reproducibility of Results; Tellurium; Tetracyclines

The specific identification and elimination of cancer cells has been a great challenge in the past few decades. In this study, the circular dichroism (CD) of cells was measured by a self-designed special system through the folate-conjugated chiral nano-sensor. A novel method was established to recognize cancer cells from normal cells according to the chirality of cells based on their CD signals. After a period of interaction between the nano-sensor and cells, the sharp weakening of CD signals was induced in cancer cells but normal cells remained unchanged. The biocompatibility of the nano-sensor was evaluated and the result showed that it exhibited significant cytotoxic activity against cancer cells while no obvious damage on normal cells. Notably, the research indicated that the nano-sensor may selectively cause apoptosis in cancer cells, and thus, have the potential to act as an antitumor agent.

Topics: Apoptosis; Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; Circular Dichroism; Female; Folic Acid; Humans; Neoplasms; Quantum Dots; Sulfides; Tellurium

A simple method was developed in this work for facile and visual detection of S

Topics: Cadmium Compounds; Fluorescence; Limit of Detection; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) are new types of fluorescent nanomaterials which can be utilized as ideal agents for intracellular tracking, drug delivery, biomedical imaging and diagnosis. It is urgent to understand their potential toxicity and the interactions with the toxin-susceptible vascular system, especially vascular endothelial cells. In this study, we intended to explore whether the cytotoxicity of CdTe (cadmium telluride) QDs was partly induced by nitrosative stress in vascular endothelial cells. Our results showed that the intracellular amount of CdTe QDs was gradually increased in a dose- and time-dependent manner, and a concentration-dependent decrease in viability were observed when incubated with CdTe QDs of 20-80 nM. The peroxynitrite level was significantly up-regulated by QDs treatment, which indicated the nitrosative stress was activated. Furthermore, nitrotyrosine level was increased after 24 hr CdTe QDs exposure in a dose-dependent manner, which suggested that CdTe QDs-induced nitrosative stress was associated with tyrosine nitration in EA.hy926. In addition, CdTe QDs induced EA.hy926 apoptosis, and the percentage of cells with low Δψm was increased after CdTe QDs treatment, indicating the mitochondrion depolarization was induced. The increased ROS fluorescence was observed in a QDs dose-dependent manner, which suggested that the oxidative stress was also involved in the CdTe QDs-induced endothelial cytotoxicity. Our work provided experimental evidence into QDs toxicity and potential vascular risks induced by nitrosative stress for the future applications of QDs.

Topics: Cadmium Compounds; Cells, Cultured; Dose-Response Relationship, Drug; Endothelial Cells; Humans; Nitrosative Stress; Quantum Dots; Tellurium; Time Factors; Umbilical Veins

The determination of chiral compounds is critically important in chemical and pharmaceutical sciences. Cysteine amino acid is one of the important chiral compounds where each enantiomer (L and D) has different effects on fundamental physiological processes. The unique optical properties of nanoparticles make them a suitable probe for the determination of different analytes. In this work, the water-soluble thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) were applied as optical nanoprobe for the simultaneous determination of cysteine enantiomers. The difference in the kinetics of the interactions between L- and D-cysteine with CdTe QDs is used for multivariate quantitative analysis. Multivariate methods are superior to univariate methods in determining the concentration of each enantiomer in the mixture without the information about the total chiral analyte concentration. As a nonlinear calibration method the radial basis function -artificial neural network (RBF-ANN) model was more successful in predicting L-and D-cysteine concentrations than the linear partial least squares regression (PLS) model.

Topics: Cadmium Compounds; Cysteine; Neural Networks, Computer; Quantum Dots; Tellurium

Topics: Cadmium Compounds; Humans; Limit of Detection; Lung Neoplasms; Mucin-1; Neoplastic Cells, Circulating; Quantum Dots; Spectrometry, Fluorescence; Tellurium

The implementation of photon-counting detectors is widely expected to be the next breakthrough in X-ray computed tomography (CT) instrumentation. A small number of prototype scanners equipped with direct-conversion detectors based on room-temperature semiconductors, such as CdTe and CdZnTe (CZT), are currently installed at medical centers. Here, we investigate the feasibility of using silicon photomultiplier (SiPM)-based scintillation detectors in photon-counting computed tomography (PCCT) scanners, as a potential alternative to CdTe and CZT detectors.. We introduce a model that allows us to compute the expected energy resolution as well as the expected pulse shape and associated rate capability of SiPM-based PCCT detectors. The model takes into account SiPM saturation and optical crosstalk, because these phenomena may substantially affect the performance of SiPM-based PCCT detectors with sub-mm pixels. We present model validation experiments using a single-pixel detector consisting of a 0.9 × 0.9 × 1.0 mm. The model was found to be in good agreement with the validation experiments, both with respect to energy resolution and pulse shape. It shows how saturation progressively degrades the energy resolution of detectors equipped with currently available SiPMs as the pixel size decreases. Moreover, the expected pulse duration is relatively long (~200 ns) with these SiPMs. However, when LuAP:Ce and LaBr. This work provides first evidence that it may be feasible to develop SiPM-based scintillation detectors for PCCT that can compete with CdTe and CZT detectors in terms of energy resolution and rate capability.

Topics: Cadmium Compounds; Feasibility Studies; Positron-Emission Tomography; Quantum Dots; Scintillation Counting; Tellurium; Tomography, X-Ray Computed

This study investigated the interacting mechanism of CdTe quantum dots (QDs) with typical plasma protein transferrin (TF) as well as the impact of the formation of QDs-TF complex on the structure of TF and the cytotoxicity of mouse primary kidney cells. Dialysis experiments and cell viability assays revealed that the formation of QDs-TF complex reduced the contents of Cd released from CdTe QDs and thus counteracted the cytotoxicity of CdTe QDs. The assay of isothermal titration calorimetry found that CdTe QDs complexed with TF majorly through hydrophobic interaction. Multi-spectroscopic measurements showed that CdTe QDs caused the loosening of polypeptide chain, the changes of secondary and tertiary structures as well as the attenuated aggregation of TF molecule. Moreover, these structural and conformational changes were attributed to the nano-effects of CdTe QDs rather than the released Cd. This study is of great significance for fully evaluating the biocompatibility of Cd-QDs and comprehensively understanding the mechanism of Cd-QDs toxicity at the molecular and cellular level.

Topics: Animals; Cadmium Compounds; Calorimetry; Cell Survival; Hydrophobic and Hydrophilic Interactions; Kidney; Male; Mice; Models, Molecular; Primary Cell Culture; Protein Structure, Secondary; Quantum Dots; Tellurium; Transferrin

To explore in vivo application of quantum dots (QDs), it is essential to understand the dynamics and energetics of interactions between QDs and proteins. Here, surface plasmon resonance (SPR) and molecular docking were employed to investigate the kinetics and thermodynamics of interactions between human serum albumin (HSA) and CdTe QDs (~3 nm) functionalized with mercaptopropionic acid (MPA) or thioglycolic acid (TGA). Kinetic analysis showed that HSA-QD interactions involved transition-complex formation. Despite the structural similarities between MPA and TGA, the [HSA-CdTe@TGA]

Topics: Cadmium Compounds; Entropy; Humans; Kinetics; Molecular Docking Simulation; Quantum Dots; Serum Albumin, Human; Sulfhydryl Compounds; Surface Plasmon Resonance; Tellurium; Thermodynamics; Thioglycolates

Topics: Cadmium Compounds; Electrophoresis, Capillary; Fluorescence; Humans; Nanoparticles; Quantum Dots; Spectrometry, Fluorescence; Superoxide Dismutase; Tellurium

Modern interventional x-ray systems are often equipped with flat-panel detector-based cone-beam CT (FPD-CBCT) to provide tomographic, volumetric, and high spatial resolution imaging of interventional devices, iodinated vessels, and other objects. The purpose of this work was to bring an interchangeable strip photon-counting detector (PCD) to C-arm systems to supplement (instead of retiring) the existing FPD-CBCT with a high quality, spectral, and affordable PCD-CT imaging option. With minimal modification to the existing C-arm, a 51×0.6 cm

Topics: Cadmium Compounds; Cone-Beam Computed Tomography; Humans; Phantoms, Imaging; Quantum Dots; Tellurium

Regarding the outbreak of the SARS Cov-2 virus pandemic worldwide, it seems necessary to provide new diagnostic methods to combat the virus. A fluorescence CdTe quantum dots-DNA (QDs-DNA) nanosensor was prepared for efficient detection of a specific target complementary DNA or RNA from the SARS Cov-2 virus using FRET experiment via forming a classic "sandwich" structure. The sequence of the complementary DNA (target DNA) is planned based on a substantial part of the SARS Cov-2 virus genome, and oligonucleotides of QDs-DNA nanoprobe are designed to complement it. The water-soluble CdTe QDs-DNA was prepared by replacing the thioglycolic acid (TGA) on the surface of QDs with capture DNA (thiolated DNA) through a ligand-exchange method. Subsequently, with the addition of complementary (target DNA) and quencher DNA (BHQ

Topics: Cadmium Compounds; DNA; Humans; Quantum Dots; Severe Acute Respiratory Syndrome; Spectrometry, Fluorescence; Tellurium

Topics: Cadmium Compounds; Quantum Dots; Spectrometry, Mass, Electrospray Ionization; Tellurium; Vigna

A novel approach to building a membrane-based disposable well-plate, here applied to cyanide detection, is described. Chitosan encapsulated CdTe quantum dots with a maximum emission at 520 nm (CS-QD520) were used as fluorophores. The CS-QD520 nanoparticle was specifically quenched by copper(II), and the quenched CS-QD520 (Cu-CS-QD520) was deposited onto a glass microfiber filter (GF/B). Subsequent introduction of cyanide ion resulted in fluorescence recovery. The "signal-ON" fluorescence linearly correlated to cyanide concentrations in the range of 38.7 to 200 μM with a limit of detection of 11.6 μM. The assay was incorporated into a membrane-based well-plate format to enhance sample throughput. A three-layer paper/glass microfiber well plate design was cut using a laser cutter and assembled using a polycaprolactone (PCL) as a bonding agent in a low-cost laminator. The experimental conditions were optimized and applied to detect cyanide in drinking water with rapid, high-throughput, low-cost analysis.

Topics: Cadmium Compounds; Chitosan; Cyanides; Fluorescent Dyes; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Tellurium

Photocatalytic water splitting using solar energy for hydrogen production offers a promising alternative form of storable and clean energy for the future. To design an artificial photosynthesis system that is cost-effective and scalable, earth abundant elements must be used to develop each of the components of the assembly. To develop artificial photosynthetic systems, we need to couple a catalyst for proton reduction to a photosensitizer and understand the mechanism of photo-induced electron transfer from the photosensitizer to the catalyst that serves as the fundamental step for photocatalysis. Therefore, our work is focused on the study of light driven electron transfer kinetics from the quantum dot systems made with inorganic chalcogenides in the presence of Ni-based reduction catalysts. Herein, we report the synthesis and characterization of four Ni(II) complexes of tetradentate ligands with amine and pyridine functionalities (N2/Py2) and their interactions with CdTe quantum dots stabilized by 3-mercaptopropionic acid. The lifetime of the quantum dots was investigated in the presence of the Ni complexes and absorbance, emission and electrochemical measurements were performed to gain a deeper understanding of the photo-induced electron transfer process.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Coordination Complexes; Electrochemistry; Electrodes; Electron Transport; Hydrogen; Kinetics; Light; Luminescence; Nickel; Photosynthesis; Quantum Dots; Solubility; Tellurium; Water

A new electrochemical device based on a combination of nanomaterials such as Printex 6L Carbon and cadmium telluride quantum dots within a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film was developed for sensitive determination of amoxicillin. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using X-ray diffraction, confocal microscopy, transmission electron microscopy and voltammetric techniques. The synergy between these materials increased the electrochemical activity, the electron transfer rate and the electrode surface area, leading to a high magnitude of the anodic peak current for the determination of amoxicillin. The electrochemical determination of the antibiotic was carried out using square-wave voltammetry. Under the optimised experimental conditions, the proposed sensor showed high sensitivity, repeatability and stability to amoxicillin determination, with an analytical curve in the amoxicillin concentration range from 0.90 to 69 μmol L

Topics: Amoxicillin; Animals; Anti-Bacterial Agents; Bridged Bicyclo Compounds, Heterocyclic; Cadmium Compounds; Carbon; Electrochemical Techniques; Electrodes; Food Contamination; Limit of Detection; Milk; Polymers; Polystyrenes; Quantum Dots; Tellurium

We described a highly sensitive and selective strategy for sensing of human serum albumin (HSA) by constructing a reversible fluorescent "turn-off-on" sensor. Monodispersed cadmium telluride quantum dots (CdTe QDs) were synthesized by using a simple aqueous phase synthesis method, which exhibited strong green fluorescence. The CdTe QDs fluorescence was first quenched using resveratrol through dynamic quenching type, that is to say, excited states CdTe QDs collided with resveratrol. HSA can cooperate with resveratrol to dissociate CdTe QDs/resveratrol, leading to the recovered fluorescence of CdTe QDs. Therefore, a facile reversible fluorescent "turn-off-on" sensor can be developed for HSA detection. In a wide concentration range of HSA (0.0237-100 μg mL

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescence; Humans; Limit of Detection; Quantum Dots; Resveratrol; Serum Albumin, Human; Tellurium

Colorimetric sensor array is a sensitive, rapid, and inexpensive detection technology which simulates human olfaction system based on various organic dyes. In this work, a sensor array based on acid-sensitive CdTe QDs coupled with chemometrics method was developed and proved to be a rapid, accurate and sensitive method for identification of 32 kinds of Chinese traditional cereal vinegars (CTCV). The specificity of identification of this method was mainly depends on the organic acids and melanoidins of CTCV. Among them, organic acids can quench the fluorescence of QDs through enhancing their electron transfer (hydrogen bond) and resonance energy transfer, and the fluorescence intensity of melanoidin was closely related to the brewing technology and aging year of CTCV. The types and aging time of 32 CTCV can be 100% identified at a dilution of 1000 by partial least squares discriminant analysis, when the latent variables were 4. And only one kind of QDs is needed instead of various organic dyes to this kind of colorimetric sensor array. Except for vinegar, this method can also be used in the identification of other food which rich in organic acid.

Topics: Acetic Acid; Cadmium Compounds; Colorimetry; Fluorescence; Hydrogen-Ion Concentration; Quantum Dots; Solutions; Tellurium; Thioglycolates

Novel boronate affinity imprinted quantum dots (BA-CdTe@MIPs QDs) were used to develop a selective and sensitive fluorescent nanosensor for determination of cis-diol-containing flavonoids such as quercetin (Qu), baicalein (Bai) and luteolin (Lut) based on controllable oriented surface imprinting approach. The boronate affinity imprinted silica was used as recognition elements. Under the optimum conditions, the imprinting factor (IF) for Qu, Bai and Lut was evaluated to be 9.42, 6.58 and 10.91, respectively. The results indicated that the boronate affinity quantum dots coated with imprinted silica were successfully prepared. The obtained BA-CdTe@MIPs QDs provided high selectivity and high sensitivity for cis-diol-containing flavonoids such as quercetin and luteolin. The BA-CdTe@MIPs QDs exhibited linear decrease in fluorescence intensity with the increase of concentration of quercetin in the 0.05-25 μM concentration range. The detection limit (LOD) is evaluated to be 0.02 μM. The obtained fluorescent nanosensor could be successfully applied to efficient detection of cis-diol-containing flavonoids in onion skin and human urine samples. The recoveries for the spiked onion skin and urine samples were evaluated to be 83.50-104.00% and 86.67-105.00%, respectively. Clearly, this study provides a rapid and efficient fluorescent detection tool for cis-diol-containing flavonoids in real samples.

Topics: Boronic Acids; Cadmium Compounds; Flavanones; Flavonoids; Humans; Limit of Detection; Luteolin; Male; Molecular Imprinting; Onions; Quantum Dots; Quercetin; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

Topics: Cadmium Compounds; Cell Line; Humans; Male; Prostatic Neoplasms; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; Cobalt; Electrochemical Techniques; Humans; Infrared Rays; Limit of Detection; Luminescent Measurements; Nanoparticles; Tellurium

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL-1 to 10 ng mL-1, with a low limit of detection (LOD, 0.18 pg mL-1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers.

Topics: Amyloid beta-Peptides; Antibodies, Monoclonal; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Humans; Immunoassay; Limit of Detection; Photochemical Processes; Quantum Dots; Sulfides; Tellurium; Tin Compounds

Mosquito-borne arboviruses compromise human health worldwide. Due to resistance to chemical insecticides, natural compounds have been studied to combat mosquitoes. Previous works have demonstrated a larvicidal activity of the water-soluble Moringa oleifera lectin (WSMoL) against Aedes aegypti, suggesting a mechanism of action based on the interaction between lectin and chitin present in the larvae's peritrophic matrix. In this work, it was investigated the WSMoL activity against Aedes aegypti larvae, by using luminescent bioconjugates of WSMoL conjugated to l-glutathione capped CdTe quantum dots. The conjugation was confirmed by ITC experiments, presenting high enthalpy associated to hydrogen bond interactions between nanoparticles and lectins. The bioconjugate luminescence stability was evaluated by the quantum yield (QY) at different pHs, ionic strengths and heat treatment time. The best parameters reached were pH 7.0, absence of electrolytes and heat treatment, giving QY = 4.4 %. The larvae were exposed to the bioconjugates and analyzed by confocal and fluorescence microscopy. CdTe-WSMol were detected along the entire midgut tract, suggesting a strong interaction with peritrophic matrix and lumen of the Aedes aegypti.

Topics: Aedes; Animals; Biomarkers; Cadmium Compounds; Glutathione; Hot Temperature; Hydrogen Bonding; Hydrogen-Ion Concentration; Larva; Lectins; Luminescence; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Moringa oleifera; Quantum Dots; Tellurium; X-Ray Diffraction

The excellent optical property and relatively low toxicity of CdTe/ZnS core/shell quantum dots (QDs) make them an advanced fluorescent probe in the application of biomedicines, particularly in neuroscience. Thus, it is important to evaluate the biosafety of CdTe/ZnS QDs on the central nervous system (CNS). Our previous studies have suggested that the high possibility of CdTe/ZnS QDs being transported into the brain across the blood-brain barrier resulted in microglial activation and a shift of glycometabolism, but their underlying mechanism remains unclear. In this study, when mice were injected intravenously with CdTe/ZnS QDs through tail veins, the microglial activation, polarized into both M1 phenotype and M2 phenotype, and the neuronal impairment were observed in the hippocampus. Meanwhile, the increased pro- and anti-inflammatory cytokines released from BV2 microglial cells treated with CdTe/ZnS QDs also indicated that QD exposure was capable of inducing microglial activation in vitro. We further demonstrated that the glycolytic shift from oxidative phosphorylation switching into aerobic glycolysis was required in the microglial activation into M1 phenotype induced by CdTe/ZnS QD treatment, which was mediated through the mTOR signaling pathway. The findings, taken together, provide a mechanistic insight regarding the CdTe/ZnS QDs inducing microglial activation and the role of the glycolytic shift in it.

Topics: Animals; Cadmium Compounds; Cell Line; Glycolysis; Hippocampus; Male; Mice, Inbred ICR; Microglia; Oxidative Stress; Phenotype; Quantum Dots; Signal Transduction; Sulfides; Tellurium; TOR Serine-Threonine Kinases; Zinc Compounds

Topics: Animals; Cadmium Compounds; Hepatocytes; Mice; Oxidative Stress; Quantum Dots; Superoxide Dismutase; Tellurium

Magnetic nanoparticles have demonstrated considerable capacity for theranosis purposes due to their unique characteristics, including magnetic properties, comparable size to biomolecules, favorable conjugations of drugs and biomolecules, ability to labeling, and capability of sensing, separation, detection, and targeted drug delivery. They could be exploited in magnetic resonance imaging as the contrast agents and also warmed as exposed to an external magnetic AC field that could be applied in hyperthermia. Here, progresses and advances in the strategy and assembly of fluorescent magnetic nanoparticles are presented for stem cell tracing and drugs/biomolecules targeting into cells.

Topics: Animals; Cadmium Compounds; Cell Differentiation; Cell Line, Tumor; Cell Survival; Cells, Cultured; Diagnostic Imaging; Fluorescence; Humans; Hyperthermia, Induced; Magnetite Nanoparticles; Mesenchymal Stem Cells; Mice, Inbred BALB C; Mice, Inbred C57BL; Quantum Dots; Receptors, Chemokine; Silicon Dioxide; Staining and Labeling; Tellurium

Proton neutron gamma-x detection (PNGXD) is a novel imaging concept being investigated for tumor localization during proton therapy that uses secondary neutron interactions with a gadolinium contrast agent (GDCA) to produce characteristic photons within the 40-200 keV energy region. The purpose of this study is to experimentally investigate the feasibility of implementing this procedure by performing experimental measurements on a passive double scattering proton treatment unit. Five experimental measurements were performed with varying concentrations and irradiation conditions. Photon spectra were measured with a 25 mm

Topics: Cadmium Compounds; Contrast Media; Feasibility Studies; Gadolinium; Gamma Rays; Humans; Monte Carlo Method; Neoplasms; Neutrons; Phantoms, Imaging; Proton Therapy; Quantum Dots; Tellurium

The paper by the authors Hau and Liu (Spectrochim Acta A Mol Biomol Spectrosc. 2019 Sep 5;220:117104) showed the effects of mercaptopropionic acid- CdTe quantum dots to the antioxidant enzymes catalase and superoxide dismutase molecules and then demonstrates the subsequent quantum dots toxic effects at a cellular level, and they proposed a mechanism of QD induced apoptosis and cell death involving oxidative stress, revealing their potential risk in the biomedical applications. QD concentrations were not determined according to the Cd concentrations in the QD that could be measured via ICP-MS. In conclusion, since cell viability above 80% as non-toxic based on ISO 10993-5, CdTe QDs cannot be considered as toxic. Also, according to the literature only CAT and SOD enzyme activities are not enough to claim oxidative stress formation.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Catalase; Cells, Cultured; Hepatocytes; Humans; MCF-7 Cells; Mice; Oxidative Stress; Quantum Dots; Superoxide Dismutase; Tellurium

An efficient signaling on-off mechanism was first proposed by integrating exciton-plasmon coupling and exciton energy transfer into cathodic PEC bioassays. This signaling on-off mechanism has endowed the cathodic PEC biosensor with powerful capability for ultrasensitive and specific detection of target DNA.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; DNA Probes; Electrochemical Techniques; Electrodes; Gold; Humans; K562 Cells; Light; Limit of Detection; Metal Nanoparticles; Nickel; Nucleic Acid Hybridization; Photochemistry; Quantum Dots; Tellurium

The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE) based on a CdTe semiconductor hybrid pixel detector, for coded aperture imaging. This probe can be adopted for various tasks in nuclear medicine such as preoperative sentinel lymph node localization, breast imaging with

Topics: Cadmium Compounds; Gamma Cameras; Gamma Rays; Humans; Neoplasms; Phantoms, Imaging; Photons; Radionuclide Imaging; Radiosurgery; Reproducibility of Results; Semiconductors; Signal-To-Noise Ratio; Tellurium

In this study, a metabolomic analysis was used to reveal the neurotoxicity of the CdTe/ZnS QDs via microglia polarization. A gas chromatography-mass spectrometer (GC-MS) was applied to uncover the metabonomic changes in microglia (BV-2 cell line) after exposure to 1.25 μM CdTe/ZnS QDs. 11 annotated metabolic pathways (KEGG database) were significantly changed in all exposed groups (3 h, 6 h, 12 h), 3 of them were related to glucose metabolism. The results of the Seahorse XFe96 Analyzer indicated that the CdTe/ZnS QDs increased the glycolysis level of microglia by 86% and inhibited the aerobic respiration level by 54% in a non-hypoxic environment. In vivo study, 3 h after the injection of CdTe/ZnS QDs (2.5 mM) through the tail vein in mice, the concentration of the CdTe/ZnS QDs in hippocampus reached the peak (1.25 μM). The polarization level of microglia (Iba-1 immunofluorescence) increased 2.7 times. In vitro study, the levels of the extracellular TNF-α, IL-1β and NO of BV-2 cells were all increased significantly after a 6 h or 12 h exposure. According to the results of the Cell Counting Kit-8, after a 6 h or 12 h exposure to the CdTe/ZnS QDs, the exposed microglia could significantly decrease the number of neurons (HT-22 cell line). This study proved that CdTe/ZnS QDs could polarize microglia in the brain and cause secondary inflammatory damage to neurons. There are potential risks in the application of the CdTe/ZnS QDs in brain tissue imaging.

Topics: Animals; Cadmium Compounds; Cell Polarity; Gas Chromatography-Mass Spectrometry; Glycolysis; Hippocampus; Metabolomics; Mice; Microglia; Neurotoxicity Syndromes; Quantum Dots; Sulfides; Tellurium; Zinc Compounds

Cefixime is a third generation orally administered cephalosporin that is frequently used as a broad spectrum antibiotic against various gram-negative and gram-positive bacteria. In this study, a simple and sensitive fluorescent sensor for the determination of the cefixime and ctDNA was established based on the CdTe:Zn

Topics: Biosensing Techniques; Cadmium Compounds; Cefixime; Circulating Tumor DNA; Electron Transport; Fluorescence; Humans; Quantum Dots; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Tellurium

A method is described for the simultaneous determination of hepatocellular carcinoma-associated microRNA-122 and microRNA-199a/b-3p. This probe consists of two kinds of nanomaterials. The first comprises CdTe@CdS core-shell quantum dots which, on excitation at 375 nm give two emissions, with peak wavelengths at 543 (g-QDs) and at 627 nm (r-QDs). The second comprises gold nanoparticles acting as a quencher. In the absence of the target, g-QD-N1 and r-QD-N2 are stable due to the fluorescence stability. With the addition of microRNA-122 and microRNA-199a/b-3p, g-QD-N1 and r-QD-N2 are conjugated to the surface of AuNP-S1/S2 through base complementary pairing. As a result, fluorescence resonance energy transfer (FRET) occurs, resulting in a decrease at 550 nm and 635 nm respectively, which can realize the simultaneous detection of two different microRNAs. Detection is achieved within 50 min. The detection limits (3σ/k) are 0.2 nM for microRNA-122 and 0.5 nM for microRNA-199a/b-3p. The clinical applicability of the assay was demonstrated by detecting microRNAs in human serum and different cell lysates. Graphical abstractSchematic for the simultaneous determination of microRNA-122 and microRNA-199a/b-3p by FRET.

Topics: Biosensing Techniques; Cadmium Compounds; Carcinoma, Hepatocellular; Fluorescence Resonance Energy Transfer; Fluorometry; Humans; Limit of Detection; Liver Neoplasms; MicroRNAs; Neoplasms; Nucleic Acid Hybridization; Quantum Dots; Sulfides; Tellurium

The myelodysplastic syndromes (MDS) are a very heterogeneous group of myeloid disorders characterized by peripheral blood cytopenias and increase risk of transformation to acute myeloid leukemia (AML). Daunorubicin (DNR) is an indispensable drug for the treatment of MDS and AML. However, its side effects including cardiac toxicity and bone marrow suppression severely limit clinical application. Many researches reported high expression of CD123 antigen on high-risk MDS cells, so we constructed a novel drug delivery system comprising daunorubicin-loaded CdTe QDs conjugated with anti-CD123 mAbs (DNR-CdTe-CD123) to develop targeted combination chemotherapy for MDS.. CdTe conjugated antiCD123 through amide bond, co-loaded with DNR with electrostatic bonding. Then, we determined characterization and release rate of DNR-CdTe-CD123. The therapeutic effect and side effect of drug delivery system were evaluated through in vitro and in vivo experiments.. CdTe showed appropriate diameter and good dispersibility and DNR was loaded into CdTes with high encapsulation efficiency and drug loading. The maximum drug loading and encapsulation efficiency were 42.08 ± 0.64% and 74.52 ± 1.81%, respectively, at DNR concentration of 0.2mg/mL and anti-CD123 mAbs volume of 5ul (100ug/mL). Flow cytometry (FCM) showed that CD123 antigen was highly expressed on MUTZ-1 cells, and its expression rate was 72.89 ± 10.67%. In vitro experiments showed that the inhibition rate and apoptosis rate of MUTZ-1 cells treated with DNR-CdTe-CD123 were higher than those in the other groups (. The system of DNR-CdTe-CD123 enhances the therapeutic effects and reduce the side effects of DNR, thus providing a novel platform for MDS treatment.

Topics: Animals; Antibodies, Monoclonal; Apoptosis; Cadmium Compounds; Caspase 3; Daunorubicin; Drug Delivery Systems; Humans; Interleukin-3 Receptor alpha Subunit; Mice, Inbred BALB C; Mice, Nude; Myelodysplastic Syndromes; Quantum Dots; Tellurium; Toxicity Tests; Xenograft Model Antitumor Assays

Herein, a triple-helix molecular switch photoelectrochemical (PEC) biosensor is developed for ultrasensitive and selective detection of microRNA based on position-controllable CdS//CdTe signal enhancement and switching accompanying the signal amplification of a three-dimensional DNA walking machine. The developed PEC biosensor exhibits excellent analytical performance for microRNA-141 detection with a wide linear range from 5 aM to 100 fM, a low detection limit of 1.3 aM and outstanding selectivity.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Limit of Detection; MicroRNAs; Photochemical Processes; Sulfides; Tellurium

Immunoassays such as the enzyme-linked immunosorbent assay (ELISA) are utilized extensively for detecting protein biomarkers and small molecules in healthcare, environmental monitoring, and food analysis. Unfortunately, the current strategies for immunoassays often require sophisticated apparatus such as a microplate reader, which might not be available in resource-limited areas. To mitigate this problem, we designed a compact smartphone based-device and a multicolor response immunosensor. First, we designed a compact and cost-effective 3D-printed attachment, where a light-emitting diode was used as a light excitation source and a smartphone captured the fluorescent emission signals. Second, by combining quantum dots hybrid and chemical redox reaction, multiple color responses were displayed in the presence of the analyte at different concentrations. Third, solutions with distinct tonality could be readily distinguished by the naked eye and they were suitable for quantitative analysis using the hue-saturation-lightness color space based on a smartphone application. The versatility of the proposed sensing system was demonstrated by implementing an indirect competitive ELISA for analyzing trace drug residues in foodstuffs. The multicolor response of this sensing strategy allows us to visually quantify drug residues in foodstuffs. Moreover, the smartphone-based immunosensor can assess the exact concentration of the analyte by using a self-designed mobile application. The proposed assay provides a highly sensitive performance that the limit of detection was 0.37 ng/mL by visual detection and 0.057 ng/mL using the compact device. Due to its advantages in terms of portability, straightforward visual detection, high sensitivity, and cost effectiveness, the proposed immunosensor has great potential for applications in areas without access to laboratories or expensive infrastructure.

Topics: Animals; Cadmium Compounds; Chickens; Drug Residues; Food Contamination; Glucose Oxidase; Hydrogen Peroxide; Immunoassay; Limit of Detection; Poultry Products; Printing, Three-Dimensional; Quantum Dots; Selenium Compounds; Silicon Dioxide; Smartphone; Tellurium

Recent studies reveal a great value of interleukin-8 (IL-8), a pro-inflammatory cytokine, as a potent biomarker for early diagnosis of oral cancer. Herein, a new electrochemical method is proposed to detect IL-8 by facilely incorporating DNA-templated quantum dots (QDs). In principle, target IL-8 is first treated with the reducing agent tris(2-carboxyethyl)phosphine (TCEP) to yield active thiols and then captured by antibody-functionalized magnetic beads (MBs). Thereafter, via the Michael addition reaction between the active thiol and maleimide group, a maleimide-modified DNA probe is linked to the surface of MBs, which can initiate a process of rolling circle amplification. In this way, long-range DNA strands are generated on the MB surface, subsequently recruiting DNA-templated CdTe/CdS QDs (DNA-QDs) to act as electrochemical reporters. By tracing the responses of DNA-QDs, the method allows IL-8 detection in a linear range from 5 to 5000 fg/mL with a detection limit of 3.36 fg/mL. The selectivity, reproducibility, and applicability in complex serum samples are also demonstrated to be favorable, indicating that the method may have a great potential in the future. More importantly, the use of TCEP treatment in the method not only provides a facile way to incorporate DNA-QDs, avoiding the complicated and time-consuming preparation process of antibody-DNA conjugates or functional nanomaterials; but also makes the method capable of being extended to detect other protein biomarkers in view of widespread presence of disulfides, which may hold a broad potential to facilitate efficient biosensing designs.

Topics: Antibodies, Immobilized; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Humans; Immobilized Nucleic Acids; Interleukin-8; Limit of Detection; Mouth Neoplasms; Quantum Dots; Sulfides; Tellurium

A fluorescence probe was delicately designed for the detection of malachite green (MG) in water and fish samples. Through the electrostatic self-assembly of CdTe QDs on the surface of polystyrene (PS) microspheres, the fluorescence signal was amplified. After grafting molecularly imprinted film, the fluorescence probe of MIP@PS@CdTe was fabricated and applied to the detection of MG based on fluorescence quenching. The linear range of MG detection was 0.01-20 μmol L

Topics: Animals; Cadmium Compounds; Environmental Monitoring; Microspheres; Models, Chemical; Molecular Imprinting; Polystyrenes; Quantum Dots; Rosaniline Dyes; Spectrometry, Fluorescence; Tellurium

Molecularly imprinted polymer (MIP)-based optosensing materials capable of direct, reliable, and highly selective detection of small organic analytes in complex aqueous samples hold great promise in many bioanalytical applications, but their development remains a challenging task. Addressing this issue, well-defined hydrophilic "turn-on"-type ratiometric fluorescent MIP microspheres are developed via a versatile and modular strategy based on the controlled/"living" radical polymerization method. Its general principle was demonstrated by the synthesis of red CdTe quantum dot (QD)-labeled silica particles with surface-bound atom transfer radical polymerization (ATRP)-initiating groups via the one-pot sol-gel reaction and their successive grafting of a thin fluorescent 2,4-D (an organic herbicide)-MIP layer (labeled with green organic fluorophores bearing both nitrobenzoxadiazole (NBD) and urea interacting groups) and hydrophilic poly(glyceryl monomethacrylate) (PGMMA) brushes via surface-initiated ATRP. The introduction of PGMMA brushes and rationally selected dual fluorescence labeling (i.e., red CdTe QDs being inert to 2,4-D and green NBD showing fluorescence "light-up" upon binding 2,4-D) onto MIP particles afforded them excellent complex aqueous sample-compatibility (due to their largely enhanced hydrophilicity) and analyte binding-induced "turn-on"-type ratiometric fluorescence changes, respectively. Such advanced MIP particles proved to be promising optosensing materials, which had a detection limit of 0.13 μM and showed obvious fluorescent color change upon binding different concentrations of 2,4-D in the undiluted pure milk. Moreover, they were successfully applied for direct and highly selective quantification of 2,4-D in the undiluted pure goat and bovine milks with good recoveries (97.9%-104.5%), even in the presence of several analogues of 2,4-D.

Topics: 2,4-Dichlorophenoxyacetic Acid; Animals; Cadmium Compounds; Cattle; Fluorescence; Food Contamination; Goats; Herbicides; Hydrophobic and Hydrophilic Interactions; Methylmethacrylates; Microspheres; Milk; Molecular Imprinting; Quantum Dots; Silicon Dioxide; Tellurium

Environmental particulate matter, especially ultrafine particles (< 100 nm in diameter), can damage the endothelium and favor cardiovascular disease in the general population. With the wide application of nanomaterials, exposure to nanoscale particles (nanoparticles) in the environment is increasing. Systematic study of the interaction of nanoparticles with plasma proteins is critically important for understanding the cardiovascular toxicity of nanomaterials. We combined kinetics and thermodynamics information from surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) and conformational data from fluorescence spectroscopy and circular dichroism (CD) to explore the binding mechanism between cadmium telluride quantum dots (CdTe QDs) and plasma proteins. Special attention was paid to the interaction between CdTe QDs and coagulation-related proteins and the effects of CdTe QDs on protein conformation. The results showed that the binding affinities of CdTe QDs and plasma proteins depend on the nature of the protein and follow the order of fibrinogen (FIB)> plasminogen (PLG) > thrombin (TM) > metallothionein-II (MT-II) > human serum albumin (HSA). The interaction was primarily attributed to hydrophobic forces and the spontaneity of the occurrence of the interaction, and the protein secondary structures of FIB and PLG were changed significantly. The information gained in this study might shed light on the potential toxicity of QDs to the cardiovascular system.

Topics: Blood Proteins; Cadmium Compounds; Humans; Kinetics; Molecular Structure; Particle Size; Quantum Dots; Surface Properties; Tellurium; Thermodynamics

A magnetic-separation-dual-targets fluorescent biosensor was fabricated to detect terminator nopaline synthase (TNOS) and promoter of cauliflower mosaic virus 35s (P35S) in transgenic soybean based on incorporation of bicolor CdTe quantum dots carried by silica nanospheres. In this protocol, the fixed probes for TNOS or P35S were magnetized firstly with Fe

Topics: Amino Acid Oxidoreductases; Biosensing Techniques; Cadmium Compounds; Caulimovirus; DNA Probes; DNA, Viral; Ferrosoferric Oxide; Fluorescent Dyes; Glycine max; Gold; Limit of Detection; Nanospheres; Nucleic Acid Hybridization; Plants, Genetically Modified; Promoter Regions, Genetic; Quantum Dots; Reproducibility of Results; Tellurium; Viral Proteins

To ensure food safety and to prevent unnecessary foodborne complications this study reports fast, fully automated process for histamine determination. This method is based on magnetic separation of histamine with magnetic particles and quantification by the fluorescence intensity change of MSA modified CdSe Quantum dots. Formation of Fe

Topics: Cadmium Compounds; Ferric Compounds; Fluorescence; Fluorescent Dyes; Food Contamination; Histamine; Limit of Detection; Magnetic Phenomena; Metal Nanoparticles; Quantum Dots; Silanes; Spectrometry, Fluorescence; Tellurium; Titanium; Wine

Acoustofluidic methods, with advantages including simplicity of device design, biocompatible manipulation, and low power consumption, have been touted as promising tools for point-of-care (POC) testing. Here, we report a cell-phone-based acoustofluidic platform that uses acoustic radiation forces to enrich nanoscale analytes and red and green fluorescence nanoparticles (SiO

Topics: Acoustics; Cadmium Compounds; Cell Phone; Fluorescence; Hemoglobins; Humans; Nanoparticles; Point-of-Care Testing; Quantum Dots; Silicon Dioxide; Tellurium

This study assesses the sex-specific effects induced by CdTe QDs, on the marine mussel Mytilus galloprovincialis in comparison to its dissolved counterpart. A 14 days exposure to CdTe QDs and dissolved Cd was conducted (10 μg Cd L

Topics: Animals; Cadmium; Cadmium Compounds; Ecosystem; Gonads; Lipid Peroxidation; Mytilus; Oxidative Stress; Quantum Dots; Tellurium; Water Pollutants, Chemical

CdTe quantum dots (QDs) are still widely considered as excellent fluorescent probes because of their far more superior optical performance and fluorescence efficiency than non‑cadmium QDs. Thus, it is important to find ways to control their toxicity. In this study, CdTe QDs and CdTe@ZnS QDs both could cause IL-1ß-mediated inflammation following with pyroptosis in BV2 cells, but the toxic effects caused by CdTe@ZnS QDs was weaker than CdTe QDs, which demonstrated the partial protection of ZnS shell. When investigating the molecular mechanisms of QDs causing the inflammatory injury, the findings suggested that cadmium-containing QDs exposure activated NF-κB that participated in the NLRP3 inflammasome priming and pro-IL-1ß expression. After that, QDs-induced excessive ROS generation triggered the NLRP3 inflammasome activation and resulted in active caspase-1 to process pro-IL-1ß into mature IL-1ß release and inflammatory cell death, i.e. pyroptosis. Fortunately, the inhibitions of caspase-1, NF-κB and ROS or knocking down of NLRP3 all effectively attenuated the increases in the IL-1ß secretion and cell death caused by QDs in BV2 cells. This study provided two methods to alleviate the toxicity of cadmium-containing QDs, in which one is to encapsulate bare-core QDs with a shell and the other is to inhibit their toxic pathways. Since the latter way is more effective than the former one, it is significant to evaluate QDs through a mechanism-based risk assessment to identify controllable toxic targets.

Topics: Animals; Cadmium Compounds; Cell Line; Inflammation; Interleukin-1beta; Mice; Microglia; NLR Family, Pyrin Domain-Containing 3 Protein; Pyroptosis; Quantum Dots; Reactive Oxygen Species; RNA, Small Interfering; Sulfides; Tellurium; Zinc Compounds

Mercaptopropionic acid (MPA) capped CdTe quantum dots (MPA-CdTe QDs) were synthesized in aqueous medium by hydrothermal method, which modified by Fe

Topics: 3-Mercaptopropionic Acid; Ascorbic Acid; Cadmium Compounds; Fluorescent Dyes; Oxidation-Reduction; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium

Developments in photovoltaic device architectures are necessary to make solar energy a cost-effective and reliable source of renewable energy amidst growing global energy demands and climate change. Thin film CdTe technology has demonstrated cost-competitiveness and increasing efficiencies due partially to rapid fabrication times, minimal material usage, and introduction of a CdSeTe alloy into a ~3 μm absorber layer. This work presents the close-space sublimation fabrication of thin, 1.5 µm CdSeTe/CdTe bilayer devices using an automated in-line vacuum deposition system. The thin bilayer structure and fabrication technique minimize deposition time, increase device efficiency, and facilitate future thin absorber-based device architecture development. Three fabrication parameters appear to be the most impactful for optimizing thin CdSeTe/CdTe absorber devices: substrate preheat temperature, CdSeTe:CdTe thickness ratio, and CdCl2 passivation. For proper sublimation of the CdSeTe, the substrate temperature prior to deposition must be ~540 °C (higher than that for CdTe) as controlled by dwell time in a preheat source. Variation in the CdSeTe:CdTe thickness ratio reveals a strong dependence of device performance on this ratio. The optimal absorber thicknesses are 0.5 μm CdSeTe/1.0 μm CdTe, and non-optimized thickness ratios reduce efficiency through back-barrier effects. Thin absorbers are sensitive to CdCl2 passivation variation; a much less aggressive CdCl2 treatment (compared to thicker absorbers) regarding both temperature and time yields optimal device performance. With optimized fabrication conditions, CdSeTe/CdTe increases device short-circuit current density and photoluminescence intensity compared to single-absorber CdTe. Additionally, an in-line close-space sublimation vacuum deposition system offers material and time reduction, scalability, and attainability of future ultra-thin absorber architectures.

Topics: Automation; Cadmium Compounds; Electricity; Luminescence; Metals; Selenium Compounds; Solar Energy; Sublimation, Chemical; Tellurium; Temperature; Vacuum; Volatilization

We herein report five different types of thiol dual capped cadmium tellurite quantum dots (CdTe QDs) namely glutathione-mercapto-propanoic acid (QD 1), glutathione-thiolglycolic acid (QD 2), L-cysteine-mercapto-propanoic acid (QD 3), L-cysteine- thiol-glycolic acid (QD 4) and mercapto-propanoic acid-thiol-glycolic (QD 5). Dual-capped CdTe QDs were prepared using a one pot synthetic method. Cadmium acetate and sodium tellurite were respectively used as cadmium and tellurium precursors. Photo-physical properties of the synthesized QDs were examined using UV-Vis and photoluminescence spectroscopy while structural characterization was performed by means of transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The influence of pH on QD characteristics (fluorescence intensity) was studied using phosphate and citrate buffers and continuous titration with HCl (0.1 N). UV-vis and photoluminescence spectra exhibited sharp absorption band edge with high intensities and improved colloidal stability. All the QDs were found to be in nano-size rang. TEM analysis revealed the presence of spherical nanoparticles while FTIR evidenced successful dual-capping of QDs. Upon pH changes, QDs 3 and 4 demonstrated more remarkable variations in fluorescence intensity than QDs 1 and 2. The pH-sensitivity of these QDs represents a promising feature for further development of potential theranostic nano-devices.

Topics: Cadmium Compounds; Hydrogen-Ion Concentration; Molecular Structure; Optical Phenomena; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Sulfhydryl Compounds; Surface Properties; Tellurium

We present a new framework for theoretical analysis of the noise power spectrum (NPS) of photon-counting x-ray detectors, including simple photon-counting detectors (SPCDs) and spectroscopic x-ray detectors (SXDs), the latter of which use multiple energy thresholds to discriminate photon energies.. We show that the NPS of SPCDs and SXDs, including spatio-energetic noise correlations, is determined by the joint probability density function (PDF) of deposited photon energies, which describes the probability of recording two photons of two different energies in two different elements following a single-photon interaction. We present an analytic expression for this joint PDF and calculate the presampling and digital NPS of CdTe SPCDs and SXDs. We calibrate our charge sharing model using the energy response of a cadmium zinc telluride (CZT) spectroscopic x-ray detector and compare theoretical results with Monte Carlo simulations.. Our analysis shows that charge sharing increases pixel signal-to-noise ratio (SNR), but degrades the zero-frequency signal-to-noise performance of SPCDs and SXDs. In all cases considered, this degradation was greater than 10%. Comparing the presampling NPS with the sampled NPS showed that degradation in zero-frequency performance is due to zero-frequency noise aliasing induced by charge sharing.. Noise performance, including spatial and energy correlations between elements and energy bins, are described by the joint PDF of deposited energies which provides a method of determining the photon-counting NPS, including noise-aliasing effects and spatio-energetic effects in spectral imaging. Our approach enables separating noise due to x-ray interactions from that associated with sampling, consistent with cascaded systems analysis of energy-integrating systems. Our methods can be incorporated into task-based assessment of image quality for the design and optimization of spectroscopic x-ray detectors.

Topics: Cadmium Compounds; Photons; Quantum Dots; Tellurium; X-Rays

The implementation of quantum dots in analytical chemistry has already advanced from basic research activities to routine applications of commercially available fluorescent agents present in sophisticated assays kits. Nevertheless, a further development of new preparation and characterization methods of nanoparticles is still required to increase the sensitivity of analytical methods substantially. Thus, in many bioanalytical applications, important molecules such as DNA, proteins, and antibodies are routinely conjugated with fluorescent tags to reach even the absolute sensitivity, that is, the capability to detect a single molecule in complex matrices. Semiconductor quantum dots have already proved to be suitable components of highly luminescent tags, probes, and sensors with broad applicability in analytical chemistry. Quantum dots provide high extinction coefficients together with wide ranges of excitation wavelengths, size- and composition-tunable emissions, narrow and symmetric emission spectra, good quantum yields, relatively long size-dependent luminescence lifetime, and low photobleaching. Most of these properties are superior when compared with conventional organic fluorescent dyes. In this chapter, optimized procedures for the preparation of water-dispersed CdTe quantum dots; their coatings and conjugation reactions with antibodies, DNA, and macrocycles; and their analyses by capillary electrophoresis are described. The potential of capillary electrophoresis for fast analyses of nanoparticles, their conjugates with antibodies and immunocomplexes with targeted antigens, is demonstrated as an example.

Topics: Antibodies; Cadmium Compounds; Electrophoresis, Capillary; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Luminescent Measurements; Nanoparticles; Nanotechnology; Proteins; Quantum Dots; Tellurium

Optical sensors are analytical tools that able to provide analyte information. There are several ways to design optical sensors. This chapter presents an interesting optical sensor to detect prilocaine, a medicine, using quantum dots (QDs) combined with molecularly imprinted polymers (QDs@MIPs). This sensor simultaneously takes advantage of QDs and molecular imprinting technology, which enables the optical device to measure prilocaine with high selectivity and sensitivity. To prepare the optical sensor, CdTe QDs were used as fluorescent probes, and an imprinted silica polymer, as the recognition system, has been constructed on the QDs via sol-gel process to increase sensor selectivity.

Topics: Cadmium Compounds; Fluorescent Dyes; Limit of Detection; Molecular Imprinting; Molecularly Imprinted Polymers; Polymers; Prilocaine; Quantum Dots; Spectrometry, Fluorescence; Tellurium

To observe blood vessels at high contrasts, we constructed a first-generation triple-sensitivity X-ray computed tomography (TS-CT) scanner using a cadmium-telluride (CdTe) detector and a triple-amplifying system. X-ray photons are absorbed by the CdTe crystal, and the electric charges produced by photons are converted into voltages using a current-to-voltage (I-V) amplifier, and the I-V output is amplified by a voltage-to-voltage (V-V) amplifier. The V-V output 1 is sent to a dual V-V amplifier through a 5.0-m-length coaxial cable and amplified to two-different outputs of 2 and 3. The three outputs 1-3 are sent to a personal computer through an analog-to-digital converter to reconstruct three tomograms simultaneously. In the TS-CT, the scattering photons from the object are extremely reduced using a 0.5-mm-diameter lead pinhole behind the object. The translation and rotation steps were 0.1 mm and 0.5°, respectively, and the spatial resolutions were 0.25 × 0.25 mm

Topics: Cadmium Compounds; Photons; Quantum Dots; Tellurium; Tomography, X-Ray Computed

Cadmium-quantum dots (Cd-QDs) possess unique properties as optoelectronic devices for sensitive detection in food and biomedicine fields. However, the toxic effects of Cd-QDs to single cells is still controversial, due to the release mechanism of QDs to Cd

Topics: Animals; Apoptosis; Cadmium Compounds; Cell Survival; Cells, Cultured; Hepatocytes; Kidney; Male; Mice, Inbred C57BL; Oxidative Stress; Quantum Dots; Tellurium

Explosive compounds, such as 2,4,6-trinitrotoluene (TNT), pose a great concern in terms of both global public security and environmental protection. There are estimated to be hundreds of TNT contaminated sites all over the world, which will affect the health of humans, wildlife, and the ecosystem. Clearly, the ability to detect TNT in soils, water supplies, and wastewater is important for environmental studies but also important for security, such as in ports and boarders. However, conventional spectroscopic detection is not practical for on-site sensing because it requires sophisticated equipment and trained personnel. We report a rapid and simple chemical sensor for TNT by using TNT binding peptides which are conjugated to fluorescent CdTe/CdS quantum dots (QDs). QDs were synthesized in the aqueous phase, and the peptide was attached directly to the surface of the QDs by using thiol groups. The fluorescent emission from the QDs was quenched in response to the addition of TNT. The response could even be observed by the naked eye. The limit of detection from fluorescence spectroscopic measurement was estimated to be approximately 375 nM. In addition to the rapid response (within a few seconds), selective detection was demonstrated. We believe this label-free chemical sensor contributes to progress for the on-site explosive sensing.

Topics: Cadmium Compounds; Chemistry Techniques, Analytical; Environmental Pollutants; Fluorescent Dyes; Peptides; Quantum Dots; Sulfides; Tellurium; Time Factors; Trinitrotoluene

Topics: Amino Acids; Cadmium Compounds; Optical Rotation; Quantum Dots; Tellurium

Realizing efficient solid-state luminescence is of great important to expand quantum dots (QDs) application fields. This work reports the preparation of CdTe@BaCO

Topics: Cadmium Compounds; Luminescence; Quantum Dots; Tellurium

In this work, Bi

Topics: Biosensing Techniques; Bismuth; Cadmium Compounds; Cell Line, Tumor; DNA; Electrochemical Techniques; Humans; Limit of Detection; MicroRNAs; Nucleic Acid Amplification Techniques; Nucleic Acid Hybridization; Povidone; Quantum Dots; Tellurium

The purpose of this work is to develop accurate computational methods to comprehensively characterize and model the clinical ExacTrac imaging system, which is used as an image guidance system for stereotactic treatment applications. The Spektr toolkit was utilized to simulate the spectral and imaging characterization of the system. Since Spektr only simulates the primary beam (ignoring scatter), a full model of ExacTrac was also developed in Monte Carlo (MC) to characterize the imaging system. To ensure proper performance of both simulation models, Spektr and MC data were compared to the measured spectral and half value layers (HVLs) values. To validate the simulation results, x-ray spectra of the ExacTrac system were measured for various tube potentials using a CdTe spectrometer with multiple added narrow collimators. The raw spectra were calibrated using a

Topics: Cadmium Compounds; Calibration; Computer Simulation; Humans; Monte Carlo Method; Phantoms, Imaging; Quantum Dots; Radiosurgery; Radiotherapy, Image-Guided; Tellurium

The present article focuses on a cradle-to-grave life cycle assessment (LCA) of the most widely adopted solar photovoltaic power generation technologies, viz., mono-crystalline silicon (mono-Si), multi-crystalline silicon (multi-Si), amorphous silicon (a-Si) and cadmium telluride (CdTe) energy technologies, based on ReCiPe life cycle impact assessment method. LCA is the most powerful environmental impact assessment tool from a product perspective and ReCiPe is one of the most advanced LCA methodologies with the broadest set of mid-point impact categories. More importantly, ReCiPe combines the strengths of both mid-point-based life cycle impact assessment approach of CML-IA, and end-point-based approach of Eco-indicator 99 methods. Accordingly, the LCA results of all four solar PV technologies have been evaluated and compared based on 18 mid-point impact indicators (viz., climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, human toxicity, photochemical oxidant formation, particulate matter formation, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, ionising radiation, agricultural land occupation, urban land occupation, natural land transformation, water depletion, metal depletion and fossil depletion), 3 end-point/damage indicators (viz., human health, ecosystems and cost increases in resource extraction) and a unified single score. The overall study has been conducted based on hierarchist perspective and according to the relevant ISO standards. Final results show that the CdTe thin-film solar plant carries the least environmental life cycle impact within the four PV technologies, sequentially followed by multi-Si, a-Si and mono-Si technology.

Topics: Cadmium Compounds; Ecosystem; Humans; Quantum Dots; Solar Energy; Tellurium

Since CdTe quantum dots (QDs) are still widely considered as advanced fluorescent probes because of their far superior optical performance and fluorescence efficiency over non-cadmium QDs, it is important to find ways to control their toxicity.. In this study, the adverse effects of two cadmium-containing QDs, ie, CdTe QDs and CdTe@ZnS QDs, on the nervous system of nematode. Firstly, we observed that cadmium-containing QD exposure-induced immune responses and neurobehavioral deficit in nematode. Even though the milder immune responses and neurotoxicity of CdTe@ZnS QDs compared with CdTe QDs indicated the protective role of ZnS coating, the inhibitions of NLRP3 expression and ROS production completely reduced the IL-1ß-mediated inflammation. This provided valuable information that inhibiting target molecules is an effective and efficient way to alleviate  the toxicity of cadmium-containing QDs, so it is important to evaluate QDs through a mechanism-based risk assessment.

Topics: Animals; Brain; Cadmium Compounds; Caenorhabditis elegans; Cell Line; Inflammasomes; Inflammation; Interleukin-1beta; Male; Mice, Inbred ICR; Microglia; NLR Family, Pyrin Domain-Containing 3 Protein; Quantum Dots; Reactive Oxygen Species; Sulfides; Tellurium; Zinc Compounds

The needing of rapid and sensitive detection method for pesticides is increasing, to facilitate its detection without complicated instruments. Herein, a novel paper-based senor was developed for the visual detection of three carbamate pesticides (metolcarb, carbofuran, and carbaryl) based on CdTe quantum dots (QDs) and nano zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (nano ZnTPyP) with a "turn-off-on" mode. This fluorescence sensing model could be applied in the highly selective and sensitive detection of carbamate pesticides both by fluorescence spectrometry or paper-based sensors. Based on the extracted RGB color values of paper, the partial least squares regression (PLSR) was used to accurately quantify the concentrations of carbamate pesticides in different food matrices (apple, cabbage and tea water). This method featured in high speed, low price and high accuracy, and provided a new strategy for the detection of food safety.

Topics: Cadmium Compounds; Carbamates; Fluorescence; Food; Food Analysis; Limit of Detection; Metalloporphyrins; Nanostructures; Pesticide Residues; Porphyrins; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Zinc Compounds

Topics: Adrenergic beta-Agonists; Animals; Cadmium Compounds; Clenbuterol; Electrochemical Techniques; Food Contamination; Limit of Detection; Liver; Luminescent Agents; Luminescent Measurements; Luminol; Molecularly Imprinted Polymers; Nanotubes, Carbon; Pork Meat; Reproducibility of Results; Swine; Tellurium

Topics: Acetylcholinesterase; Butyrylcholinesterase; Cadmium Compounds; Enzyme Assays; Humans; Lab-On-A-Chip Devices; Limit of Detection; Male; Microfluidic Analytical Techniques; Paper; Polymers; Quantum Dots; Tellurium; Thiophenes

Sialic acids (SAs) modulate essential physiological and pathological conditions, including cell-cell communication, immune response, neurological disorders, and cancer. Besides, SAs confer negative charges to cell membranes, also contributing to hemorheology. Phenylboronic acids, called as mimetic lectins, have been highlighted to study SA profiles. The association of these interesting molecules with the optical properties of quantum dots (QDs) can provide a deeper/complementary understanding of mechanisms involving SAs. Herein, we explored the thiol affinity to the QD surface to develop a simple, fast and direct attachment procedure to functionalize these nanocrystals with 3-mercaptophenylboronic acids (MPBAs). The functionalization was confirmed by fluorescence correlation spectroscopy and inductively coupled plasma spectrometry. The conjugate specificity/efficiency was proved in experiments using red blood cells (RBCs). A labeling >90% was found for RBCs incubated with conjugates, which reduced to 17% after neuraminidase pretreatment. Moreover, QDs-MPBA conjugates were applied in a comparative study using acute (KG-1) and chronic (K562) myelogenous leukemia cell lines. Results indicated that KG-1 membranes have a greater level of SA, with 100% of cells labeled and a median of fluorescence intensity of ca. 2.5-fold higher when compared to K562 (94%). Therefore, this novel QDs-MPBA conjugate can be considered a promising nanoplatform to evaluate SA contents in a variety of biological systems.

Topics: Cadmium Compounds; Cell Line, Tumor; Cell Membrane; Humans; Particle Size; Quantum Dots; Sialic Acids; Spectrometry, Fluorescence; Surface Properties; Tellurium

The bioaccumulation potential and toxic effects of engineered nanomaterials (ENMs) to earthworms are poorly understood. Two studies were conducted following OECD TG 222 on Eisenia fetida to assess the effects of CdTe QDs with different coatings and soil ageing respectively. Earthworms were exposed to carboxylate (COOH), ammonium (NH

Topics: Animals; Bioaccumulation; Cadmium Compounds; Models, Theoretical; Oligochaeta; Particle Size; Quantum Dots; Reproduction; Soil; Soil Pollutants; Surface Properties; Tellurium; Time Factors

A sensitive fluorescent microfluidic sensor based on carbon quantum dots (CQDs), cadmium telluride quantum dots (CdTe QDs) aerogel and glucose oxidase (GOx) for urinal glucose detection was fabricated via a simple method. CQDs, emitting green fluorescence (emission peak at 520 nm) and the CdTe QDs, emitting red fluorescence (emission peak at 620 nm) under 365 nm ultraviolet irradiation, were synthesized. The as-prepared CQDs, CdTe QDs and GOx (C/CdTe QD-GOx) were mixed in a certain ratio and were then introduced into the microfluidic chip to construct a three-dimensional porous aerogel sensor after freeze-drying. A ratiometric fluorescence response was realized through the quenching of the red fluorescence by H2O2 produced from the glucose/GOx reaction, while the green fluorescence intensity stays constant. A small change in the ratio of the two fluorescence intensities led to a clear change in the fluorescent colour of the sensor, which can be easily observed under a UV lamp. The microsensor displayed a serial colour change from red to green with the changes in glucose concentration. The intensity ratio between the red fluorescence and green fluorescence (R/G value) indicates the glucose concentration. In our experiments, the optimal concentration ratio of CdTe QDs and CQDs was 0.5 : 1, and the optimal response time was 5 min. The detection range of glucose concentration was from 0 mM to 13 mM, and the detection limit was 0.223 mM. We also found that this glucose sensor has excellent selectivity, specificity and stability. The as-prepared microsensor can be stably stored for 30 days under -20 °C. Such a C/CdTe QD-GOx aerogel based microfluidic assay sensor provides a new approach towards the optical and quantitative detection of glucose, which enables daily urine glucose monitoring for the diabetic patients in a convenient way.

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescent Dyes; Glucose Oxidase; Glycosuria; Humans; Hydrogels; Hydrogen Peroxide; Limit of Detection; Microfluidics; Quantum Dots; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium

Topics: Animals; Bacterial Proteins; Bacteriological Techniques; beta-Galactosidase; Cadmium Compounds; Enzyme Assays; Escherichia coli; Galactosides; Humans; Limit of Detection; Mass Spectrometry; Metal Nanoparticles; Milk; Oxidation-Reduction; Quantum Dots; Silver; Spectrometry, Fluorescence; Tellurium; Urine

Urolithiasis is a common disease that affects 5% to 8.8% of the world population with high recurring frequency. Therefore, there is an urgent need for the rapid and efficient diagnostics of urolithiasis. In this study, we developed a quantum dots (QDs)-based sensor for detecting urolithiasis oxalate. Urolithiasis oxalate was quantified by reducing Cu

Topics: Cadmium Compounds; Cell Line; Humans; Limit of Detection; Oxalates; Quantum Dots; Tellurium; Time Factors; Urolithiasis

Despite the benefits of mammography investigations, some studies have shown that X-ray exposure from the mammography screening itself can statistically cause breast cancer in a small fraction of women. Therefore, a dose reduction in mammography is desirable. At the same time, there is a demand for a higher spatial resolution in mammographic imaging. The most promising way to achieve these goals is the use of advanced photon-processing semiconductor X-ray detectors with optimum sensor materials. This study addresses the investigation of the optimum semiconductor sensor material for mammography in combination with the photon-processing detector Medipix3RX. The influence of K-shell fluorescence from the sensor material on the achievable contrast-to-noise ratio is investigated, as well as the attenuation efficiency. The three different sensor materials, CdTe, GaAs, and Si are studied, showing advances of CdTe-sensors for mammography. Furthermore, a comparison of the contrast-to-noise ratio between a clinical Se-detector and Medipix3RX detectors with Si- and CdTe-sensors is shown using a self-produced mammography phantom that is based on real human tissue.

Topics: Arsenicals; Cadmium Compounds; Female; Gallium; Humans; Mammography; Quantum Dots; Tellurium

Multiplex detection and quantification of bacteria in water by using portable devices are particularly essential in low and middle-income countries where access to clean drinking water is limited. Addressing this crucial problem, we report a highly sensitive immunoassay sensor system utilizing the fluorescence technique with magnetic nanoparticles (MNPs) to separate target bacteria and two different types of quantum dots (CdTe and Ni doped CdTe QDs) incorporated into a passive microfluidic chip to transport and to form sandwich complexes for the detection of two target bacteria, namely Escherichia coli (E. coli) and Salmonella enteritidis (S. enteritidis) in less than 60 min. The assay is carried out on a capillary driven microfluidic chip that can be operated by merely pipetting the samples and reagents, and fluorescence measurements are done by using a handheld fluorescence spectrophotometer, which renders the system portable. The linear range of the method was found to be 10

Topics: Cadmium Compounds; Enterobacter; Escherichia coli; Microfluidics; Quantum Dots; Salmonella enteritidis; Staphylococcus aureus; Tellurium

The use of dual recognition and multiple detection modes is an attractive strategy for realising sensors with improved selectivity and accuracy. Herein, a molecularly imprinted polymer (MIP)-based sensor is developed for amoxicillin detection based on two detection modes (fluorescence and electrochemiluminescence) and dual recognition. First, graphene oxide loaded with CdTe quantum dots/gold nanoparticles (GO/CdTe/Au NPs) is coated onto an indium tin oxide (ITO) electrode. Then, 4-mercapto-calix[6]arene is bonded to GO/CdTe/Au NPs as the first recognition element, which then form a host-guest complex with the target molecule amoxicillin. Subsequently, as the second recognition element, an MIP is prepared on the ITO electrode. After amoxicillin is removed from the MIP, specific identification sites for amoxicillin are obtained. Furthermore, the GO/CdTe/Au NPs can generate fluorescence and electrochemiluminescence signals that are effectively quenched by amoxicillin. Therefore, on/off switching of these signals can be achieved through the elution or adsorption of amoxicillin. The dual detection modes are complementary and provide mutual authentication, which can improve the detection accuracy and application scope. Moreover, the dual recognition sites for amoxicillin, improve detection selectivity. The fluorescence and electrochemiluminescence modes have detection ranges of 5-1000 × 10

Topics: Amoxicillin; Cadmium Compounds; Gold; Limit of Detection; Metal Nanoparticles; Molecular Imprinting; Quantum Dots; Tellurium

The aim of this study was to investigate the detailed mechanisms of hepatotoxicity induced by cadmium telluride quantum dots (CdTe-QDs) in BALB/c mice after intravenous injection. The study investigated oxidative stress, apoptosis, and effects on mitochondria as potential mechanistic events to elucidate the observed hepatotoxicity. Oxidative stress in the liver, induced by CdTe-QD exposure, was demonstrated by depletion of total glutathione, an increase in superoxide dismutase activity, and changes in the gene expression of several oxidative stress-related biomarkers. Furthermore, CdTe-QD treatment led to apoptosis in the liver via both intrinsic and extrinsic apoptotic pathways. Effects on mitochondria were evidenced by the enlargement and increase in the number of mitochondria in hepatocytes of treated mice. CdTe-QDs also caused changes in the levels and gene expression of electron transport chain enzymes, depletion of ATP, and an increase in the level of the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a regulator of mitochondrial biogenesis. The findings from this study suggest that CdTe-QDs-induced hepatotoxicity might have originated from mitochondrial effects which resulted in oxidative stress and apoptosis in the liver cells. This study provides insight into the biological effects of CdT-QDs at the tissue level and the detailed mechanisms of their toxicity in animals. The study also provides important data for bridging the gap between

Topics: Animals; Cadmium Compounds; Dose-Response Relationship, Drug; Hepatocytes; Male; Mice; Mice, Inbred BALB C; Mitochondria; Quantum Dots; Tellurium

In this work, the carbon dots (CDs) were prepared by one-pot hydrothermal method with chitosan as a carbon source and hydrogen peroxide as an oxidant, this route is a novel, simple and green. The prepared CDs has a relatively high photoluminescence (PL) quantum yield (QY) (18.9%) and good water solubility. CdTe quantum dots (CdTe QDs) possess the characteristic of responding to pH rapidly. So a ratiometric fluorescent probe for measuring pH was constructed using the prepared CDs and CdTe QDs. Under the excitation of 330 nm, the probe shows dual (blue and red) emission with peaks at 430 and 600 nm, respectively. When the pH of the solution changes, the blue fluorescence intensity of the CDs remains stable as a reference signal, while the red fluorescence intensity of CdTe QDs changes accordingly. This method has obvious pH-sensitive feature, stable fluorescence properties, and a great linear relationship with pH values in the range of pH 3.0-11.0. What is more, the method can monitor proton-producing enzyme-catalyzed reactions by acting as a ratiometric pH probe.

Topics: Cadmium Compounds; Carbon; Hydrogen-Ion Concentration; Quantum Dots; Tellurium

A paper-based visual fluorescence immunoassay is presented for the detection of matrix metalloproteinase-7 (MMP7) that is related to renal cancer. The method is based on the distance-dependent fluorescence quenching of CdTe quantum dots (QDs) on a nitrocellulose membrane by Ag

Topics: Cadmium Compounds; Fluorescence; Humans; Metal Nanoparticles; Quantum Dots; Tellurium

The basic photoactive matrixes on transparent electrodes are essential for the performance of photoelectrochemical (PEC) biosensors. Herein, we demonstrate an optimized fabrication strategy toward a reliable ITO/TiO2/AuNP photoanode by sequential deposition of TiO2/Au nanoparticles (Au NPs) on indium tin oxide (ITO) substrates. The identified fabrication conditions include spin-coating tetraisopropyl titanate on ITO slices followed by in situ electrodeposition of Au NPs and finally the thermal annealing treatment. By the conjugation of the thiolated hairpin NH2-DNA sequence and CdTe quantum dots (QDs) onto the thus-prepared photoanodes, a novel PEC sensor for the ultrasensitive detection of miRNA was constructed. The proposed PEC sensor offered advantages including simple structure, storage stability and excellent detection reproducibility as well as sensitivity and specificity toward miRNA-21. Finally, we found that this PEC displayed a broad detection linear range of 1.0 fM to 1.0 nM with a low detection limit of 0.37 fM. This PEC sensor can also excellently discriminate the mismatched miRNA. Moreover, the PEC sensor also showed a satisfactory result in normal human serum sample analysis. These findings emphasized the importance of basic photoactive matrixes for the fabrication of PEC sensors, providing solid fundamental insights for future application of metal oxide substrates for other PEC applications, especially PEC biosensors.

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Gold; Humans; Limit of Detection; Metal Nanoparticles; MicroRNAs; Quantum Dots; Reproducibility of Results; Tellurium

Future biomedical applications of nanoparticles will encounter these particles with patients' serum which might affect the properties and stability of quantum dots and serum proteins at the desired site of action. Therefore, it is essential to clarify the patient-specific serum components, serve as major interaction partners, the spatial distribution of these, and consequently the time-dependent effects of nanoparticle-protein interaction. Here, a biochemical and structural study was performed on the protein corona formation and the corresponding interaction of different sizes of CdTe QDs with human serum proteins to determine if the mutual effects on optical properties by using electrophoresis, chemiluminescence, and fluorescence spectroscopy. The results revealed that interaction with human serum significantly enhanced the stability and photoluminescence of quantum dots. Structural studies of HSA-coated CdTe QDs also showed that corona formation has no adverse effects on protein structure, and the reduction in fluorescence emissions of HSA is due to the direct quenching of aromatics residues by the quantum dot. Improving nanoparticle properties, as well as the lack of structural changes in HSA, can be very useful in biomedical applications and in vivo studies where stability is important.

Topics: Blood Proteins; Cadmium Compounds; Circular Dichroism; Humans; Immunoglobulin G; Particle Size; Protein Corona; Quantum Dots; Serum Albumin; Spectrometry, Fluorescence; Tellurium

A sensitive and robust fluorescent assay of 6-MP is described which relies on the facile assembly of a fluorescence nanoprobe by design of silica nanosphere encapsulated CdTe quantum dots (CdTe QDs) as scaffold, coupling with chemically tethered folic acid (FA)-protected silver nanoparticles (AgNPs) that function as responsive element. In this way a stable ternary core-shell-satellite nanostructure with dual-emission signals can be established. On binding to the target molecules, 6-MP, FA molecules initially occupied by AgNPs are liberated to give dose-dependent fluorescence emission, which can further form a self-calibration ratiometric fluorescence assay using CdTe QDs as an internal reference. The nanoprobe color vividly changes from red to blue, enabling the direct visual detection. The linear concentration range is 0.15~50 μM with the detection limit of 67 nM. By virtue of the favorable selectivity and robust assays, the nanoprobe was applied to 6-MP detection in urine samples, with recoveries from 97.3 to 106% and relative standard deviations (RSD) less than 5%. Graphical abstract.

Topics: Cadmium Compounds; Fluorescent Dyes; Folic Acid; Humans; Limit of Detection; Mercaptopurine; Metal Nanoparticles; Nanostructures; Quantum Dots; Reproducibility of Results; Silicon Dioxide; Silver; Spectrometry, Fluorescence; Tellurium

Numerical models are an alternative to measurements of x-ray energy spectra when validated by comparative methods that assess the similarity of experimental and calculated spectra. In this work, we compared x-ray energy spectra using several methodologies and determined the methodology with highest statistical power among them. Experiments and Monte Carlo (MC) simulations were used to generate a set of 65 experimental and simulated x-ray mammography spectra pairs typically used in mammography applications. They were generated using Tungsten and Molybdenum targets and Molybdenum and Rhodium filters. The x-ray beams were transmitted through breast tissue equivalent material (bTEM) plates with different glandularities and thicknesses, and the transmitted beam was detected using solid-state x-ray spectrometry with a Cadmium Telluride (CdTe) diode. The MC simulations used the PENELOPE code. Additional uncertainties, beyond that from counting, were propagated using the MC method. Quantitative comparative methods based on the [Formula: see text] statistics, the first and second half-value layers, the mean energy, the effective energy, and the non-parametric u-test were applied and their specificity (true negative rate) was assessed. The polyenergetic normalized glandular dose (DgNp) to a 6 cm breast of 50/50 glandularity was derived from the spectra. In this work, the [Formula: see text] statistics attained the highest score; therefore, it is the most indicated metric for the x-ray energy spectra comparative evaluations. The contribution of the additional uncertainties was important, being responsible for up to 98% of the spectra total uncertainty and shifting the mean of the evaluated [Formula: see text] to 1.2(1), compatible with its expected value. The use of non-parametric test is discouraged by our results, since it failed to distinguish spectra pairs that resulted in up to 72% discrepant DgNp.

Topics: Algorithms; Cadmium Compounds; Computer Simulation; False Positive Reactions; Female; Humans; Image Processing, Computer-Assisted; Mammography; Models, Statistical; Models, Theoretical; Molybdenum; Monte Carlo Method; Normal Distribution; Reproducibility of Results; Rhodium; Sensitivity and Specificity; Spectrophotometry; Tellurium; Tungsten; Uncertainty; X-Rays

A simple, direct fluorescent sensor was developed to simultaneously determine nitric oxide and hydrogen sulfide based on 4-(((3-aminonaphthalen-2-yl)amino)methyl)benzoic acid (DAN-1)-functionalized CdTe/CdS/ZnS quantum dots (QDs@DAN-1). In this sensor, DAN-1 could specifically recognize nitric oxide and yield highly fluorescent naphtho triazole (DAN-1-T). Meanwhile, the fluorescence intensity of the QDs could be quenched by hydrogen sulfide. The QDs and DAN-1-T could be simultaneously excited at 365 nm, and their maximum emission wavelengths were 635 and 440 nm, respectively. Nitric oxide and hydrogen sulfide were simultaneously determined by monitoring two different fluorescence signals. The limits of determination for nitric oxide and hydrogen sulfide were 0.051 and 0.13 μM, respectively. The QDs@DAN-1 sensor was also applied to determine nitric oxide and hydrogen sulfide in human plasma. This sensor may provide a new strategy for investigating the relationship between nitric oxide and hydrogen sulfide and elucidating their roles in related physiological and pathophysiological processes at the same time.

Topics: Cadmium Compounds; Humans; Hydrogen Sulfide; Nitric Oxide; Quantum Dots; Tellurium

A new fluorescent light switch method, which based on N‑acetyl‑l‑cysteine capped CdTe QDs (NALC-CdTe QDs), was developed for the detection of gallic acid (GA). The QDs possess a fluorescence emission wavelength at 520nm and with symmetric fluorescence. When KMnO

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescent Dyes; Gallic Acid; Limit of Detection; Linear Models; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Tea; Tellurium

Due to their simplicity of design and operation, homogeneous bioassays have been of great interest to researchers. Herein, a label-free and free separation fluorescence sensing platform was constructed for the determination of nucleic acid and prostate specific antigen (PSA) using CdTe QDs as the signal molecule. In our previous work, we surprisingly found that the CdTe QDs can selectively distinguish Ag+ and the C-Ag+-C complex, which was the basis of the sensor. On the basis of the selective cation exchange reaction (CER), combined with the signal amplification of the strand displacement reaction (SDR), this work was first applied for the sensitive analysis of DNA. There are two types of hairpin structures in this sensing system, including the recognition probe (HP) and Ag+, which formed the C-Ag+-C structure, and the hairpin structure formed by the helper DNA itself. In this work, target DNA can trigger the SDR that generates lots of HP-helper double-stranded DNA (dsDNA) and recycles the target DNA while releasing a large amount of Ag+, thus quenching the fluorescence signal of CdTe QDs to achieve the highly sensitive detection of DNA. In order to verify the versatility of this system using DNA as a bridge and aptamers as recognition probes, we extended the system to the detection of PSA. After examining its experimental performance, it was determined that this method displayed good analytical capability for DNA in the range of 10-13-10-10 M and PSA in the range of 10-13-10-10 g mL-1 with low 25 fM and 30 fg mL-1 limits of detection (LODs), respectively; high selectivity for both the target sequence and protein was shown. In addition, this platform was successfully used for the analysis of PSA in serum samples.

Topics: Aptamers, Nucleotide; Base Sequence; Biosensing Techniques; Cadmium Compounds; DNA; DNA Probes; Fluorescence; Humans; Inverted Repeat Sequences; Limit of Detection; Male; Nucleic Acid Hybridization; Prostate-Specific Antigen; Quantum Dots; Silver; Spectrometry, Fluorescence; Tellurium

An electrochemiluminescent (ECL) biosensor is described for the determination of the breast cancer biomarker microRNA. The method is based on the amplification via target cyclic regeneration through a system of hairpin DNA probes, primers, and Klenow fragment of DNA polymerases combined with CdTe quantum dots (QDs) and gold nanoparticles. The assay is performed by exploiting the luminescence properties of CdTe-QDs and K

Topics: Biomarkers, Tumor; Biosensing Techniques; Breast Neoplasms; Cadmium Compounds; DNA-Directed DNA Polymerase; Electrochemical Techniques; Female; Gold; Humans; Luminescent Measurements; Magnetite Nanoparticles; MicroRNAs; Particle Size; Quantum Dots; Surface Properties; Tellurium

A molecularly imprinted polymer (MIP) anchored on the surface of CdTe quantum dots (QDs) was fabricated and used as a fluorescent probe for sulfadiazine (SDZ) detection in seawater. CdTe QDs was used as photoluminescent material, SDZ as the template, 3-aminopropyltriethoxysilane (APTES) as the functional monomer and tetraethyl orthosilicate (TEOS) as the cross-linking agent. Characterizations of MIP-QDs were analyzed by Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM) and Scanning electron microscope (SEM). The conditions were optimized for the detection of MIP-QDs to SDZ. The mechanism of fluorescence quenching was studied by UV-Vis absorption spectroscopy and fluorescence spectroscopy. Under optimal conditions, the fluorescence intensity of MIP-QDs decreased linearly between 4- and 20 μM SDZ with a good correlation coefficient of 0.995. The limit of detection is 0.67 μM and the recovery is between 91.8 and 109.4% with RSD lower than 3.9%. These results indicated that MIP-QDs for SDZ detection in seawater was developed successfully.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Fluorescent Dyes; Limit of Detection; Microscopy, Electron, Transmission; Molecular Imprinting; Polymers; Propylamines; Quantum Dots; Seawater; Silanes; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Sulfadiazine; Tellurium; Water Pollutants, Chemical

Topics: Adult; Aged; Biosensing Techniques; Cadmium Compounds; Cell Line, Tumor; DNA Probes; DNA, Viral; Glass; Humans; Limit of Detection; Magnetic Phenomena; Male; Microscopy, Fluorescence; Nucleic Acid Hybridization; Papillomaviridae; Papillomavirus Infections; Quantum Dots; Spectrometry, Fluorescence; Squamous Cell Carcinoma of Head and Neck; Tellurium

We evaluated the durability of cadmium telluride (CdTe) solar cells upon proton beam irradiation as well as the possibility of achieving a dosimeter usable in proton beam therapy by applying 100 MeV of pencil beam scanning (PBS) irradiation. Specifically, a 100 MeV proton PBS beam was applied at irradiation doses of 0, 1012, 1013, 1014, and 1015 cm-2. According to the results, the remaining factors (defined as the ratio of the degraded value to the initial value) of open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF), and efficiency (ƞ) which are solar cell performance parameters, were approximately 89%, 44%, 69%, and 30%, respectively, compared to those of the reference cell (without irradiation) at the highest dose of 1×1015 cm-2. In particular, the conversion efficiency, which is the main factor, was approximately 70% of that of the reference cell even at a high fluence of 1×1014 cm-2. In addition, we observed the projected range of the hydrogen atoms based on the PBS beam energy using the Tool for Particle Simulation software and assessed the amount of fluence accumulated in a CdTe cell. As the energy increased, the fluence accumulated inside the cell tended to decrease owing to the characteristics of the Bragg peak of the proton. Thus, the radiation damage to the cell induced by the proton beam was reduced. The results of this study are expected to provide valuable reference information for research on dosimetry sensors composed of thin-film solar cells, serving as the basis for future application in proton beam therapy with CdTe solar cells.

Topics: Cadmium Compounds; Energy-Generating Resources; Hardness; Phantoms, Imaging; Protons; Radiation Dosage; Software; Surface Properties; Tellurium

Topics: Cadmium Compounds; Cations; Cell Line, Tumor; Humans; Ion Exchange; Metal Nanoparticles; MicroRNAs; Signal Processing, Computer-Assisted; Tellurium

A light-driven multifunctional Janus micromotor for the removal of bacterial endotoxins and heavy metals is described. The micromotor was assembled by using the biocompatible polymer polycaprolactone for the encapsulation of CdTe or CdSe@ZnS quantum dots (QDs) as photoactive materials and an asymmetric Fe

Topics: Cadmium Compounds; Escherichia coli; Ferric Compounds; Glucose; HeLa Cells; Humans; Light; Lipopolysaccharides; Materials Testing; Mercury; Multifunctional Nanoparticles; Peroxides; Polyesters; Quantum Dots; Tellurium; Time-Lapse Imaging

The water-soluble semiconductor quantum dots (QDs) serve as optically detectable models of nanoparticles and are commonly applied as photoluminescent markers in biological systems. The unicellular algae represent a popular model system suitable to evaluate pollution-induced effects. There is growing experimental evidence that release of metal ions cannot account for potential toxicity of metal containing nanoparticles, however, the underlying mechanisms are not clearly understood. Surrounding environment and illumination conditions are among the most important factors affecting the stability of QDs as well as the interaction between nanoparticles and cells such as microalgae. The measurements of changes in photoluminescence (PL) of QDs and autofluorescence (AF) of microalgae can thus be used as a non-invasive screening method for detecting mutual effects of nanoparticles and algae cells on each other under natural conditions. In this study, CdTe quantum dots (a peak of PL at 550 nm) capped with a mercaptosuccinic acid (MSA) were introduced into aqueous ionic medium containing wild type green freshwater microalgae Scenedesmus and Chlorella sp. cells under artificial and natural ambient illumination. The spectroscopy and microscopy techniques were applied to observe both the influence of the microalgae on the spectral properties of negatively charged CdTe-MSA quantum dots and the effects of nanoparticles on the microalgae. The presence of algae cells revealed a protecting effect on both medium-dependent and radiation-induced changes in photoluminescence properties of QDs, which could be related with the increased stability of the capping layer. The effects on cellular AF intensity and the interaction of QDs with cellular surface depended on type of microalgae. The observed changes in AF spectral properties and AF induction signals can't be explained only by the photodegradation of QDs and have revealed the ability of nanoparticles to retard the photoadaptation of wild type microalgae under naturally varying illumination conditions.

Topics: Cadmium Compounds; Chlorella; Fluorescent Dyes; Fresh Water; Light; Microalgae; Quantum Dots; Scenedesmus; Spectrometry, Fluorescence; Surface Properties; Tellurium; Thiomalates

A rolling-mediated cascade (RMC) amplification strategy is described for improved visualization of profiling glycans of mucin 1 (MUC 1) on cell surfaces. CdTe quantum dots (QDs) are used as fluorescent labels. The RMC based amplification allows even distinct glycoforms of MUC1 to be visualized on the surface of MCF-7 cell via an amplified Förster resonance energy transfer (FRET) imaging strategy that works at excitation/emission wavelengths of 345/610 nm. This is achieved by utilizing antibody against MUC1 modified with the fluorescent label 7-amino-4-methylcoumarin-3-acetic acid (AMCA) as the energy donor in FRET. The QDs (used to label surface glycans) act as acceptors. N-Azidoacetylgalactosamine-Acetylated (Ac4GalNAz) as a non-natural azido sugar, can be incorporated into the glycans of the cell surface, which can promote further labeling. The method has the advantage of only requiring a small amount of non-natural sugar to be introduced in metabolic glycan labeling since too much of an artificial sugar will interfere with the physiological functions of cells. Graphical abstract Schematic for the DNA rolling-mediated cascade (RMC)-assisted metabolic labeling of cell surface glycans by using CdTe quantum dots as labels and an intramolecular amplified FRET strategy for imaging glycans on a specific glycosylated protein, MUC1.

Topics: Antibodies; Cadmium Compounds; Coumarins; DNA; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Humans; MCF-7 Cells; Mucin-1; Nucleic Acid Amplification Techniques; Polysaccharides; Quantum Dots; Tellurium

Herein, a novel three-dimensional (3D) DNA nanomachine with high walking efficiency via free DNA walker movement on biomimetic lipid bilayers supported by hard silica@CdTe quantum dots (SiO

Topics: Biomimetic Materials; Biosensing Techniques; Cadmium Compounds; Cell Line, Tumor; Cholesterol; Female; Humans; Immobilized Nucleic Acids; Limit of Detection; Lipid Bilayers; MCF-7 Cells; Metal Nanoparticles; MicroRNAs; Microscopy, Fluorescence; Nanotechnology; Quantum Dots; Silicon Dioxide; Tellurium

Two types of lateral flow immunochromatographic test strips (LFITS) using gold nanoparticles and fluorescent CdTe quantum dots (QDs) as signal labels, respectively, were developed for Shiga toxin type II (STX2) assays. Under optimal conditions, the corresponding visual detection limits were 25 ng mL-1 and 5 ng mL-1, respectively. The test results of gold based LFITS can be recognized directly by the naked eye, whereas the visualized results of CdTe QDs based LFITS can be observed by the aid of a UV lamp. Both assays showed good specificity and stability. The inexpensive LFITS were promising for the rapid clinical detection of STX2.

Topics: Antibodies; Cadmium Compounds; Chromatography, Affinity; Colorimetry; Fluorescent Dyes; Fluorometry; Gold; Limit of Detection; Metal Nanoparticles; Quantum Dots; Reagent Strips; Shiga Toxin 2; Tellurium

Various diseases are closely related to simultaneous changes of multiple miRNAs expression levels. It's of great significance to develop photoelectrochemical (PEC) biosensors for multiple miRNA detection for both clinical diagnosis and biological mechanisms research. In this work we designed a novel PEC biosensor for simultaneous dual miRNA detection for the first time. Two nanocomposites, CdTe loaded carbon nitride nanosheets (CdTe-C

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Electrodes; Graphite; Humans; Hydrogels; Limit of Detection; MicroRNAs; Nanocomposites; Tellurium

Fluorescent CdTe nanocrystals (NCs) capped with beta-cyclodextrin (β-CD) are successfully synthesized by host-guest supramolecular assembly of the hydrophobic alkyl chains of N-acetyl-l-cysteine (NAC) on the surface of CdTe NCs and eco-friendly β-CD via the promising simple hydrothermal method in our experiments. The as-prepared NCs display better stability and lower toxicity compared with traditional those only capped with NAC. Specially, cytotoxicity experiments to human umbilical vein endothelial cells in vitro and zebrafish embryo toxicological tests in vivo are performed to determine the toxicity of CdTe NCs. For their practical applications, the promising red-luminescent NCs are employed as stable and low poison red phosphors to fabricate white light-emitting diodes (WLEDs) with remarkable color-rendering index (CRI) being 91.6. This research offers significance for solving the difficulty in toxicity and instability of heavy metal based NCs, which has potential applications in future optoelectronic devices and biomarkers.

Topics: Animals; beta-Cyclodextrins; Cadmium Compounds; Cell Survival; Embryo, Nonmammalian; Human Umbilical Vein Endothelial Cells; Humans; Lethal Dose 50; Luminescent Agents; Nanoparticles; Photochemistry; Surface Properties; Tellurium; Zebrafish

The excitonic response between nanomaterials is distance-dependent, and thus, interparticle distance is a key factor in fabricating diverse photoelectrochemical (PEC) systems. Current studies focus on DNA-mediated regulation of interparticle distance. However, limited by high demands of base-pairing and flexibility of DNA, it is hard for DNA to achieve precise regulation, especially in a short distance. To pursue better PEC performances in bioanalyses, alternative biological materials should be explored to replace DNA as new "distance controllers". In this work, a peptide with three functional sequences is designed to control interparticle distance between positive-charged Au nanoparticles ((+) AuNPs) and negative-charged CdTe quantum dots ((-) CdTe QDs). Relying on the function of binding sequence, (+) AuNPs and (-) CdTe QDs may be separated to a certain distance by the multifunctional peptide. In this case, the excitonic response is relatively weak, and an evident PEC response can be observed. Because it contains the substrate sequence of caspase-3, the peptide is cleaved in the presence of caspase-3. As a result, without the support of intact peptide, electrostatic attraction plays a dominant role, leading to the aggregation of oppositely charged AuNPs and CdTe QDs, which strengthens the excitonic response and attenuates the PEC response. On the basis of these principles, a novel PEC approach was fabricated to sensitively quantify caspase-3. Meanwhile, caspase-3 in staurosporine-treated A549 cells are also determined by the approach, and the obtained results agree well with the fluorescent intensity of confocal images, manifesting that the proposed PEC method can monitor apoptosis in a label-free strategy. Overall, the study reveals the capability of peptides in controlling interparticle distance of nanomaterials, which may accelerate the development of peptide-based PEC analytical methods.

Topics: A549 Cells; Amino Acid Sequence; Apoptosis; Cadmium Compounds; Caspase 3; Electrochemical Techniques; Gold; Humans; Limit of Detection; Metal Nanoparticles; Peptides; Photochemistry; Quantum Dots; Staurosporine; Tellurium

The investigation of the luminescence properties of CdTe/KBr composites with encapsulated quantum dots (QDs) of different sizes was performed and the influence of the KBr matrix on the luminescence properties of CdTe QDs was studied. Encapsulation of nanoparticles by a solid matrix caused a bathochromic shift in the luminescence peak and the shift value was the larger the smaller the size of the quantum dots. Interband quantum transition theory was used to explain the influence of the matrix on the luminescence properties of the capsulated CdTe QDs. Theoretical calculations showed that the observed QD luminescence peak corresponded to a 1 s-1 s electronic transition, and its low-energy shift after the transfer of QDs from dielectric water to the KBr matrix was due to a corresponding decrease in the depths of electrons and holes potential wells.

Topics: Bromides; Cadmium Compounds; Luminescent Agents; Potassium Compounds; Quantum Dots; Tellurium

Adenosine triphosphate-binding cassette (ABC) transporters, including P-glycoprotein (Pgp) and multi-resistance associated proteins (Mrps), have been considered important participants in the self-protection of zebrafish embryos against environmental pollutants, but their possible involvement in the efflux and detoxification of quantum dots (QDs), as well as their regulation mechanism are currently unclear. In this work, gene expression alterations of ABC transporters, nuclear receptors, and oxidative stress signaling in zebrafish embryos after the treatment of mercaptopropionic acid (MPA)CdTe QDs and MPA-CdSCdTe QDs were investigated. It was observed that both QDs caused concentration-dependent delayed hatching effects and the subsequent induction of transporters like mrp1&2 in zebrafish embryos, indicating the protective role of corresponding proteins against CdTe QDs. Accompanying these alterations, expressions of nuclear receptors including the pregnane X receptor (pxr), aryl hydrocarbon receptor (ahr) 1b, and peroxisome proliferator-activated receptor (ppar)-β were induced by QDs in a concentration- and time-dependent manner. Moreover, elevated oxidative stress, reflected by the reduction of glutathione (GSH) level and superoxide dismutase (SOD) activities, as well as the dramatic induction of nuclear factor E2 related factor (nrf) 2, was also found. More importantly, alterations of pxr and nrf2 were more pronounced than that of mrps, and these receptors exhibited an excellent correlation with delayed hatching rate in the same embryos (R

Topics: 3-Mercaptopropionic Acid; Animals; ATP-Binding Cassette Transporters; Biotransformation; Cadmium Compounds; Embryo, Nonmammalian; Gene Expression Regulation; Glutathione; Inactivation, Metabolic; Multidrug Resistance-Associated Proteins; NF-E2-Related Factor 2; Oxidative Stress; PPAR-beta; Pregnane X Receptor; Quantum Dots; Receptors, Aryl Hydrocarbon; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Superoxide Dismutase; Tellurium; Zebrafish

A facile and practical ratiometric fluorescence probe based on two CdTe quantum dots (QDs) coated with molecularly imprinted polymers (MIPs) was prepared for the detection of trace malachite green (MG) in fish. Two CdTe QDs coated with MIPs were fabricated by a one-pot method using MG, (3-aminopropyl) triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) as template, functional monomer, and cross-linker, respectively. CdTe QDs with λ

Topics: Animals; Cadmium Compounds; Fishes; Fluorometry; Molecular Imprinting; Molecular Structure; Quantum Dots; Reproducibility of Results; Rosaniline Dyes; Sensitivity and Specificity; Spectroscopy, Fourier Transform Infrared; Tellurium

A electrochemical biosensing strategy was developed for green and ultrasensitive detection of tumor cells by combining aptamer-DNA concatamer-CdTe quantum dots (QDs) signal amplification probe with mercury-free anodic stripping voltammetry (ASV). First, aptamer-DNA concatamer- CdTe QDs probes were designed by DNA hybridization and covalent assembling, which contained specific recognition of aptamer and signal amplification incorporating the DNA concatamer with QDs. Meanwhile, the capture electrode, glassy carbon electrode (GCE)/Graphene oxide (GO)/Polyaniline (PANI) / Glutaraldehyde (GA) / concanavalin A (Con A) was fabricated by a layer-by-layer assembling technique. K562 cells, as model cancer cells were detected to demonstrate the feasibility of this sensing strategy. Then, novel composite, graphene (GR)- Poly diallyldimethylammonium chloride (PDDA)/L-Cysteine (L- Cys), was explored in ASV which replaced mercury electrodes using for determination of tumor cells. The proposed electrochemical biosensor showed high sensitivity with the detection limit of 60 cells mL

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Cell Line, Tumor; Cell Separation; DNA Probes; Electrochemical Techniques; Graphite; Humans; Limit of Detection; Mercury; Neoplasms; Quantum Dots; Tellurium

A kind of coenzyme A (CoA)-silver coordination complex (CoA-Ag) was in-situ developed and verified to accelerate the electron transferring and electrochemical catalysis of H

Topics: Biosensing Techniques; Cadmium Compounds; Coenzyme A; Electrochemical Techniques; Histone Acetyltransferases; Humans; Hydrogen Peroxide; Limit of Detection; Luminescent Measurements; Metal Nanoparticles; Quantum Dots; Tellurium

Microglial cells are resident immune cells in the central nervous system. Activation of microglia as induced by CdTe quantum dots (QDs) can trigger damage to neurons. To quantify the intracellular QDs, we monitored the intracellular Cd concentration in the QD-exposed mouse microglial cells (BV-2 cell line). The extent of cell injury at different times correlated with the Cd concentration in cells at that time. In addition to Cd ion detection, we also monitored the intracellular fluorescence of the QDs. More QDs accumulated in the nucleus than in the cytoplasm. Comet assays confirmed that QDs induce DNA damage. However, DNA cannot interact with QDs, so the DNA damage was not caused by CdTe QDs adducts to DNA but by the increase of the Cd ion concentration and the secondary oxidative damage. In addition to DNA damage, biofilm injury and endogenous reduced glutathione depletion were also apparent in QD-exposed BV-2 cells. These changes can be prevented or even reversed by exogenous reduced glutathione administration.

Topics: Animals; Cadmium Compounds; Cells, Cultured; DNA Damage; Glutathione; Mice; Microglia; Neurotoxicity Syndromes; Quantum Dots; Reactive Oxygen Species; Spectrophotometry, Atomic; Tellurium

In this study, the cytotoxicity of CdTe quantum dots (QDs) of various dimensions was examined using the electroporation method. The influence of the size of QDs on normal and tumour cell viability after 24 h of incubation with nanomaterials was examined. The three human cell lines were chosen for the tests: A549 (a tumour cell line derived from the lung), MRC-5 (normal fibroblasts from the lung) and HaCaT (normal keratinocytes from the skin). Accordingly, we modelled the effect of nanocrystals on various human tissues because nanoparticles can be introduced into an organism through different routes. We were also able to study which cells are more sensitive to nanoparticles: normal or tumour cells. The nanoparticles were introduced into cells through pores in the cell membranes that were generated by electrical pulses. The effectiveness of introducing nanocrystals into cells was determined as a function of the nanocrystal dimensions and accumulation locations. Moreover, the cytotoxicity of quantum dots was tested, and cell viability after electroporation was evaluated. We also investigated whether the introduced nanocrystals released cadmium ions.

Topics: A549 Cells; Cadmium Compounds; Cell Line; Cell Survival; Electroporation; Humans; Quantum Dots; Tellurium

This feature article highlights the recent advances of luminescent metal nanoclusters (MNCs) for their potential applications in healthcare and energy-related materials because of their high photosensitivity, thermal stability, low toxicity, and biocompatibility. Current studies reveal that metal cluster based hybrid systems could pave the way for energy harvesting and sensing applications. To begin with, we illustrate general synthesis methodologies for atomically precise metal nanoclusters and discuss the origin of photoluminescence properties and the electronic transitions of nanoclusters. Successively, we discuss the energy transfer and electron transfer processes in metal cluster based hybrid systems with CdTe QDs, carbon dots (C-dots), functionalized DNA and graphene oxide. Finally, we address the potential advantages of metal clusters and their hybrid systems as an optical probe for the selective detection of toxic metal ions. A tentative outlook on fundamental challenges and future opportunities of this research field is highlighted.

Topics: Cadmium Compounds; DNA; Electrons; Energy Transfer; Graphite; Luminescence; Metal Nanoparticles; Tellurium

Ascorbic acid (AA) and alkaline phosphatase (ALP) serve as an important coenzyme and enzyme in multiple biological metabolism reactions, respectively, and abnormal levels of these substrates have been associated with several diseases. Herein, a new and simple fluorescence strategy has been developed for AA and ALP sensing by exploiting CdTe quantum dots (QDs) as an effective signal indicator. This method is mainly based on the selective fluorescence-quenching reaction between Ag+ and CdTe QDs, as opposed to silver nanoparticles (Ag NPs); Ag+ can be reduced to Ag NPs by AA. Furthermore, by taking advantage of AA as a mediator, this strategy is further exploited for ALP assay given that ALP can cause the hydrolysis of l-ascorbic acid-2-phosphate (AAP), which yields AA. Under optimal conditions, controlled generation of Ag NPs and the selective recognition-based sensing system exhibit high sensitivity toward AA and ALP with limits of detection (LODs) of 3 μM and 0.25 U L-1 and linear ranges of detection from 0 to 800 μM and 1 to 1000 U L-1, respectively. Moreover, the sensor was successfully used for assaying AA in fruit juice and ALP in human serum. The results demonstrate that the proposed fluorescence strategy has significant advantages, such as its simplicity, cost-effectiveness, and rapid runtime, and the operational convenience of this label-free method further demonstrates its potential for constructing effective sensors with biochemical and clinical applications.

Topics: Alkaline Phosphatase; Ascorbic Acid; Cadmium Compounds; Chemistry Techniques, Analytical; Feasibility Studies; Metal Nanoparticles; Quantum Dots; Silver; Spectrometry, Fluorescence; Tellurium; Time Factors

A near-infrared light-activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; DNA; Electrochemical Techniques; Electrodes; Europium; Fluorides; Gold; Infrared Rays; Limit of Detection; Metal Nanoparticles; Nucleic Acid Hybridization; Printing, Three-Dimensional; Quantum Dots; Tellurium; Yttrium

Rapid detection of pesticides in fruits is an ongoing challenge. The objective of the present study was to develop novel fluorescent microfluidic paper chips for specific recognition and sensitive detection of the pesticide 2,4-D through the electron-transfer-induced fluorescence quenching mechanism. CdTe quantum dots (QDs) were deposited onto cellulose paper (base material) to yield imprinted paper chips (paper@QDs@MIPs). This method allows the transferability of the molecularly imprinted fluorescence sensor from the liquid phase to the solid phase (paper base) for rapid and portable analysis. The resultant imprinted paper chips were effectively characterized, and they exhibited ideal ordered spatial network structure, chemical stability, and fluorescence property. The paper@QDs@MIPs showed that 2,4-D binding significantly reduced the fluorescence intensity within less than 18 min, and it achieved satisfactory linearity in the range of 0.83-100 μM and high detectability of 90 nM. The recognition specificity for 2,4-D relative to its analogues was shown, and the imprinting factor was 2.13. In addition, the recoveries of the spiked bean sprouts at three concentration levels ranged within 94.2-107.0%, with a relative standard deviation of less than 5.9%. Collectively, the device provided an effective platform for rapid recognition, convenience, and detection of trace food pollutants in complex matrices, thereby ensuring food safety and further promoting surface imprinting studies.

Topics: 2,4-Dichlorophenoxyacetic Acid; Cadmium Compounds; Fluorescent Dyes; Lab-On-A-Chip Devices; Limit of Detection; Paper; Pesticides; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Time Factors

Topics: Aflatoxin B1; Antibodies, Monoclonal; Cadmium Compounds; Edible Grain; Fluorescence; Fluorescent Dyes; Food Contamination; HEK293 Cells; Humans; Immunoassay; Immunoglobulin Fab Fragments; Limit of Detection; Molecular Docking Simulation; Molecular Dynamics Simulation; Quantum Dots; Sulfides; Tellurium; Zinc Compounds

Topics: Alkaline Phosphatase; Cadmium Compounds; Energy Transfer; Fluorescence; Fluorescent Dyes; Humans; Limit of Detection; Nitrophenols; Organophosphorus Compounds; Quantum Dots; Spectrometry, Fluorescence; Sulfides; Tellurium

Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg

Topics: Aptamers, Nucleotide; Cadmium Compounds; Energy Transfer; Fluorescence; Limit of Detection; Macromolecular Substances; Mercury; Nucleic Acid Hybridization; Oligodeoxyribonucleotides; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A simple and sensitive inner filter effect and charge transfer dual response ratiometric fluorescent probe (D-RFP) for sensing glucose was developed based on etching of silver nanoprisms (Ag NPRs). The D-RFP was proposed by hybridizing red emitting CdTe QDs and blue emitting CDs into core-shell structured silica nanoparticles. In this design, when mixed Ag NPRs with the D-RFP, QDs which embedded in silica nanoparticles can be quenched by Ag NPRs via inner filter effect. Ag NPRs can be effectively etched to silver ions by H

Topics: Cadmium Compounds; Carbon; Color; Colorimetry; Diabetes Mellitus; Fluorescence; Fluorescent Dyes; Glucose; Glucose Oxidase; Humans; Hydrogen Peroxide; Limit of Detection; Oxidation-Reduction; Quantum Dots; Silicon Dioxide; Silver; Tellurium

A multifunctional DNA nanocage containing CdTe quantum dots (QDs) was prepared. It was applied to the fluorometric detection of human 8-oxoG DNA glycosylase 1 (hOGG1) by exonuclease-assisted cycling amplification technique. When loaded with the cancer drug doxorubicin (Dox), the nanocage is also a versatile probe for fluorescence imaging of cancer cells, and drug delivery to them. The presence of hOGG1 leads to the division of DNA HP1 (containing 8-oxo-dG) and formation of DNA fragments 1 and 2. Then, HP2 is added to hybridize with DNA 1 and produced lots of trigger DNA (containing nucleolin aptamer) by Exo III-aided cycling amplification. The DNA nanocage was fabricated by linking the trigger DNA to multiple specific DNA strands, and the fluorescent CdTe QDs were further conjugated to the DNA nanocage for sensitive detection of hOGG1 activity. After Dox is incorporated into the DNA nanocage, the fluorescence of Dox is turned off. Once the DNA nanocage enters the MCF-7 cells, the Dox is released and its fluorescence (measured at excitation/emission wavelengths of 480/560 nm) is turned on. The DNA nanocage containing fluorescent QDs and Dox was successfully applied to the fluorometric detection of hOGG1, fluorescence imaging, and therapy of cancer cells, which has great promise in clinical application and treatment of cancer. Graphical abstract A multifunctional DNA nanocage containing CdTe quantum dots and acting as a signalling probe was prepared. It was applied to fluorometric determination of human 8-oxoG DNA glycosylase 1 using cycling amplification technique. It also enables drug delivery to cancer cells if loaded with doxorubicin.

Topics: Cadmium Compounds; Diagnostic Imaging; DNA; DNA Glycosylases; Doxorubicin; Drug Delivery Systems; Fluorescence; Fluorescent Dyes; Fluorometry; Humans; Neoplasms; Quantum Dots; Tellurium

This work focused the implementation of FRET processes between CdTe quantum dots (QDs), acting as donors, and gold nanoparticles (AuNPs), behaving as acceptors, for the determination of several bioactive thiols such as captopril, glutathione, l-cysteine, thiomalic acid and coenzyme M. The surface chemistry of the QDs and AuNPs was adjusted with adequate capping ligands, i.e. mercaptopropionic acid and cysteamine, respectively, to guarantee the establishment of strong electrostatic interaction between them and promoting the formation of stable FRET assemblies. Under these circumstances the fluorescence emission of the QDs was completely suppressed by the AuNPs. The assayed target analytes were capable of disrupting the donor-acceptor assemblies yielding a concentration-related reversion of the FRET process and restoring QDs fluorescence emission. Distinct mechanisms, involving enhancing of the QDs quantum yield (QY), AuNPs agglomeration, nanoparticles detachment, etc., could be proposed to explain the referred FRET reversion. The developed approach assured good analytical working ranges and demonstrate adequate sensitivity for the assayed compounds, anticipating great prospective for implementing rapid, simple and reliable sensing methodologies for the monitoring of pharmaceutical, food and environmental species. However, selectivity could be a hindrance in the detection of these bioactive thiols in more complex matrices such as environmental and food samples. This problem could be circumvented through the employment of multivariate chemometric methods for the analysis and processing of whole fluorometric response. Moreover, the proposed methodology shows a great analytical versatility since it is possible to easily adapt the surface chemistry, of both QDs and AuNPs, to the chemical nature of the target analyte.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Calibration; Cysteamine; Fluorescence Resonance Energy Transfer; Gold; Linear Models; Metal Nanoparticles; Particle Size; Quantum Dots; Sulfhydryl Compounds; Tellurium

Real-time and accurate measurement of three-dimensional (3D) temperature field gradient maps of cells and tissues would provide an effective experimental method for analyzing the coupled correlation between metabolism and heat, as well as exploring the thermodynamic properties of nanoparticles under complex environments. In this work, a new principle of quantum 3D thermal imaging is proposed. The photoluminescence principle of quantum dots is expounded and CdTe QDs are prepared by aqueous phase synthesis. Fluorescence spectral characteristics of QDs at different temperatures are studied. The optimized algorithm of the optical spot double helix point spread function is proposed to improve the imaging, where optimized light energy increased by 27.36%. The design scheme of a quantum 3D thermal imaging system is presented. The measurement range is (-8 mm, +8 mm). The temperature is calculated according to the temperature-heat curve of quantum dots. The double helix point spread function has converted the defocus distance of QDs into the rotation angle of the double optical spot, thereby determining its position. The experimental results reveal that real-time 3D tracking and temperature measurements of quantum dots at the micro-nanoscale are achieved. Overall, the proposed nano-scale 3D quantum thermal imaging system with high-resolution may provide a new research direction and exploration of many frontier fields.

Topics: Algorithms; Cadmium Compounds; Cell Line, Tumor; Coculture Techniques; Fluorescence; Humans; Imaging, Three-Dimensional; Light; Nanoparticles; Quantum Dots; Tellurium; Temperature; Thermodynamics; Water

Topics: Cadmium Compounds; Carbon; Image Processing, Computer-Assisted; Monte Carlo Method; Phantoms, Imaging; Radionuclide Imaging; Silicon; Tellurium

Topics: Cadmium Compounds; Cetrimonium; Color; Fluorescence Resonance Energy Transfer; Mercury; Quantum Dots; Tellurium

Early detection of mutation carriers in predisposing genes such as BRCA1 plays an important role in disease prevention. This work developed a quantum dots-based (QDs-based) fluorescence resonance energy transfer (FRET) technique for the detection of single-base mismatch DNA in BRCA1 gene. The FRET between QDs as the donor and silver nanocluster (AgNCs) as the acceptor was designed by the strong interaction between CdTe QDs with appropriate size and dsDNA through binding to its major groove. The dsDNA was formed by the hybridization of ssDNA labeled to AgNCs with target DNA, which introduced CdTe QDs into the major grooves to place the AgNCs in close proximity to the QDs. The complementary and single-base mismatch DNA led to obviously different FRET signals. The FRET signal linearly correlated to the concentration of single-base mismatch DNA in the range of 1.5 × 10

Topics: Base Pair Mismatch; BRCA1 Protein; Cadmium Compounds; DNA; DNA Probes; Fluorescence Resonance Energy Transfer; Humans; Limit of Detection; Mutation; Nanostructures; Nucleic Acid Hybridization; Polymorphism, Single Nucleotide; Quantum Dots; Sensitivity and Specificity; Silver; Tellurium

Glibenclamide (GB), as a sulfonylurea-based medication is commonly prescribed for the treatment of type 2 diabetes. Due to its increasing consumption, there is a need to develop a simple, fast, and reliable detection method to follow its concentration in pharmaceutical and biological samples. Herein, a novel fluorometric method is developed for the sensitive measurement of GB. The method is based on the enhancing effect of GB on the fluorescence emission of mercaptopropionic acid (MPA) capped cadmium telluride quantum dots (CdTe QDs). QDs were synthesized in aqueous solution and were characterized by fluorescence spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Fluorescence intensity of QDs was enhanced by adding GB in a very low concentration. The effect of operative factors such as pH, buffer, contact time and concentration of CdTe QDs were investigated and in the optimized condition, a linear increase was achieved for the emission intensity of QDs by increasing GB concentration in the range 49-345 ng mL

Topics: Cadmium Compounds; Fluorescence; Fluorescent Dyes; Glyburide; Healthy Volunteers; Humans; Molecular Structure; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tablets; Tellurium

An electrochemiluminescence (ECL) based biosensor is described for determination of microRNAs in the A549 cell line. Firstly, graphene oxide (GO) is dripped onto a glassy carbon electrode surface to form an interface to which one end of the capture probe (with a stem-loop structure) can be anchored through π-interaction via dangling unpaired bases. The other end of the capture probe is directed away from the GO surface to make it stand upright. Target microRNAs can open the hairpin structure to form a double-stranded DNA-RNA structure. Two auxiliary probes, generating a hybridization chain reaction, are used to elongate the DNA duplex. Finally, doxorubicin-modified cadmium telluride quantum dot nanoparticles (Dox-CdTe QD) are intercalated into the base pairs of the hybrid duplexes to act as signalling molecules. The ECL signal of the Dox-CdTe QD increases proportionally with the concentration of microRNAs, specifically for microRNA-21. The assay covers a wide linear range (1 fM to 0.1 nM), has a low detection limit for microRNA-21 (1 fM), and is selective, reproducible, and stable. Graphical abstract An enzyme-free amplification electrochemiluminescent assay is described to quantitative detection of microRNA in the A549 cell line. Graphene oxide was used to immobilize capture probes obviating the special modification. Doxorubicin-modified cadmium telluride quantum dot nanoparticles are intercalated into the base pairs of the hybrid duplexes to act as signalling molecules.

Topics: A549 Cells; Biosensing Techniques; Cadmium Compounds; Doxorubicin; Electrochemical Techniques; Electrodes; Graphite; Humans; Intercalating Agents; Limit of Detection; Luminescence; MicroRNAs; Nucleic Acid Amplification Techniques; Nucleic Acid Hybridization; Particle Size; Quantum Dots; Surface Properties; Tellurium

A glassy carbon electrode was modified with carbon black and CdTe quantum dots in a chitosan film to obtained a sensor for norfloxacin (NOR) in the presence of dopamine, caffeine, and uric acid. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using spectrophotometry, X-ray diffraction, transmission electronic microscopy and voltammetry. The high electrochemical activity, fast electron transfer rate and high surface area enhanced the oxidation peak currents and shifted the peak potentials of NOR for more negative values (typically at 0.95 V vs. Ag/AgCl). Electrochemical determination of NOR was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV). Response is linear in the 0.2 to 7.4 μmol L

Topics: Cadmium Compounds; Carbon; Chitosan; Electrochemical Techniques; Electrodes; Limit of Detection; Norfloxacin; Quantum Dots; Tellurium

Quantum dots (QDs), considered as a type of excellent semiconductor nanomaterial, are widely employed and have a number of important applications. However, QDs have the potential to produce adverse effects and toxicity with the underlying molecular mechanisms not well understood. Herein, Caenorhabditis elegans was used for in vivo toxicity assessment to detect the reproductive toxicity of CdTe QDs. We found that exposure to CdTe QDs particles (≥ 50 mg/L) resulted in a defect in reproductive capacity, dysfunctional proliferation and differentiation, as well as an imbalance in oogenesis by reducing the number of cells in pachytene and diakinesis. Further, we identified a SPO-11 and PCH-2 mediated toxic mechanism and a GLP-1/Notch mediated protective mechanism in response to CdTe QDs particles (≥ 50 mg/L). Taken together, these results demonstrate the potential adverse impact of CdTe QDs (≥ 50 mg/L) exposure on oogenesis and provide valuable data and guidelines for evaluation of QD biocompatibility.

Topics: Animals; Cadmium Compounds; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cell Cycle; Oogenesis; Quantum Dots; Signal Transduction; Tellurium

This work developed a near-infrared (near-IR) light-activated non-enzymatic signal-off photoelectrochemical (PEC) immunoassay for the ultrasensitive detection of α-fetoprotein (AFP) on the basis of branched polyethylenimine (BPEI)-modified upconversion nanoparticle (UCNP)@CdTe quantum dot (QD) nanostructures by coupling with the synergistic effect of dual-purpose copper ions. Emission light originated from NaYF

Topics: alpha-Fetoproteins; Biosensing Techniques; Cadmium Compounds; Copper; Electrochemical Techniques; Humans; Immunoassay; Limit of Detection; Nanostructures; Photochemical Processes; Polyethyleneimine; Quantum Dots; Tellurium

In this work, a quick, facile and efficient approach was presented for green synthesis of cadmium telluride quantum dots (CdTe QDs) based on an aqueous extract of the Ficus johannis plant. Two extraction methods involving microwave assisted extraction (MWAE; 90 and 270 w; 15 min) and ultrasonic assisted extraction (USAE; 15 min; 45 °C) were performed as eco-friendly, effective, green and fast techniques for the extract preparation of the fruit's plant. The as-prepared plant extracts were used as natural stabilizing precursors in the synthesis of CdTe QDs. The synthesized QDs were characterized using various techniques. The average particle size of the QDs from the X-ray diffraction patterns was calculated to be 1.2 nm. UV-Vis absorption and fluorescence spectroscopic studies show a wide absorption band from 400 to 425 nm and a maximum emission peak around 470 nm, which confirmed the successful synthesis of CdTe QDs via the applied synthetic method. After synthesis and characterization of the samples, the antimicrobial properties, genotoxicity, toxicity and antifungal activities of the as-prepared CdTe QDs were investigated. In addition, antioxidant properties of the samples (QDs and extracts), were evaluated by different antioxidant assays. The results indicate the significant antimicrobial activity of the extract and CdTe QDs samples, with negligible toxicity and genotoxicity impacts.

Topics: Anti-Bacterial Agents; Antifungal Agents; Antioxidants; Bacteria; Cadmium Compounds; Ficus; Flavonoids; Fungi; Green Chemistry Technology; Meristem; Microbial Sensitivity Tests; Microwaves; Mitotic Index; Mutagens; Onions; Phenols; Phytochemicals; Quantum Dots; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium; Ultrasonics

Developing methods to determine cell type and cell state has been a significant challenge in the field of cancer diagnosis as well as in typing and quality verification for cultured cells. Herein, we report a cell profiling method based on binding interactions between cell-surface sugar-chain-binding proteins and sugar-chain-immobilized fluorescent nanoparticles (SFNPs), together with a method for cell typing and cell quality verification. Binding profiles of cells against sugar chains were analyzed by performing flow cytometry analysis with SFNPs. Discrimination analysis based on binding profiles could classify cell type and evaluate the quality of cultured cells. By applying our method to differentiated cells originating from conventional cell lines and also to mouse embryotic stem cells, we could detect the cells before and after differentiation. Our method can be utilized not only for the biofunctional analysis of cells but also for diagnosis of cancer cells and quality verification of cultured cells.

Topics: Animals; Cadmium Compounds; Cell Line, Tumor; Embryonic Stem Cells; Flow Cytometry; Humans; Lectins; Ligands; Metal Nanoparticles; Mice; Monosaccharide Transport Proteins; Sulfides; Tellurium; Trisaccharides

Indium phosphide quantum dots (QDs) have emerged as a new class of fluorescent nanocrystals for manifold applications, from biophotonics to nanomedicine. Recent efforts in improving the photoluminescence quantum yield, the chemical stability and the biocompatibility turned them into a valid alternative to well established Cd-based nanocrystals. In vitro studies provided first evidence for the lower toxicity of In-based QDs. Nonetheless, an urgent need exists for further assessment of the potential toxic effects in vivo. Here we use the freshwater polyp Hydra vulgaris, a well-established model previously adopted to assess the toxicity of CdSe/CdS nanorods and CdTe QDs. A systematic multilevel analysis was carried out in vivo, ex vivo, and in vitro comparing toxicity end points of CdSe- and InP-based QDs, passivated by ZnSe/ZnS shells and surface functionalized with penicillamine. Final results demonstrate that both the chemical composition of the QD core (InP vs CdSe) and the shell play a crucial role for final outcomes. Remarkably, in absence of in vivo alterations, cell and molecular alterations revealed hidden toxicity aspects, highlighting the biosafety of InP-based nanocrystals and outlining the importance of integrated multilevel analyses for proper QDs risk assessment.

Topics: Cadmium; Cadmium Compounds; Containment of Biohazards; Indium; Multilevel Analysis; Quantum Dots; Tellurium; Zinc Compounds

Topics: alpha-Fetoproteins; Biosensing Techniques; Cadmium Compounds; Gold; Humans; Immunoassay; Limit of Detection; Luminescent Measurements; Metal Nanoparticles; Nanocomposites; Quantum Dots; Silicon Dioxide; Tellurium

Fluorescence-based aptasensors possess high sensitivity but are complicated and usually require multistep labeling and modification in method design, which severely limit the practical applications. Here, a label-free fluorescence-based aptasensor, consisting of aptamer, gold nanoparticles (AuNPs), and cadmium telluride (CdTe) quantum dots (QDs), was developed for the detection of sulfadimethoxine (SDM) in water and fish based on the specific recognition of SDM-aptamer and the inner filter effect of QDs and AuNPs. In the absence of a target, AuNPs dispersed in salt solution because of the aptamer protection, which could effectively quench the fluorescence emission of QDs, while in the presence of SDM, AuNPs aggregated due to the specific recognition of SDM-aptamer to SDM, which resulted in fluorescence recovery. A linear response of SDM concentrations in the range of 10-250 ng mL

Topics: Animals; Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Fishes; Gold; Limit of Detection; Metal Nanoparticles; Quantum Dots; Spectrometry, Fluorescence; Sulfadimethoxine; Tellurium; Water

The photoelectrochemical (PEC) signal can be enhanced by constructing sensitization structures containing photoactive materials and appropriate sensitizers. However, usually, the photoactive materials and sensitizers were separated in independent nanostructures, thereby producing long electron-transfer path and large energy loss, which could further result in limited photoelectric conversion efficiency and PEC signals. Herein, we designed a novel sensitization nanostructure simultaneously containing the photoactive material cerium dioxide (CeO

Topics: Biosensing Techniques; Cadmium Compounds; Cerium; Electrochemical Techniques; Electrodes; Ferrosoferric Oxide; Gold; Humans; Limit of Detection; MicroRNAs; Nanostructures; Quantum Dots; Tellurium

A novel DNA hydrogel-amplified versatile fluorescence platform combined with hybridization chain reaction (HCR) and DNA walking multiple amplification was developed for ultrasensitive detection of miRNA. The DNA hydrogel was loaded with large amounts of SYBR Green (SG) I dyes or CdTe quantum dots (QDs) to assemble versatile signal probes.

Topics: Benzothiazoles; Biosensing Techniques; Cadmium Compounds; Diamines; DNA; DNA Probes; Fluorescence; Hydrogels; MicroRNAs; Nucleic Acid Amplification Techniques; Nucleic Acid Hybridization; Organic Chemicals; Quantum Dots; Quinolines; Spectrometry, Fluorescence; Tellurium

Topics: Aflatoxin B1; Cadmium Compounds; Limit of Detection; Microscopy, Electron, Transmission; Molecular Imprinting; Polymers; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium

Nowadays, label-free atomic spectrometric bioassays are attracting great research interest because of their advantages of low cost, simple design and operation, etc. Herein, a novel and simple chemical vapor generation-atomic fluorescence spectrometry (CVG-AFS)/inductively coupled plasma-mass spectrometry (ICP-MS) label-free detection method is presented for highly sensitive and selective assay of DNA and proteins. This work mainly combined a phenomenon that CdTe quantum dots (QDs) can be used to selectively differentiate free Hg2+ and the T-Hg2+-T complex, with the use of simple membrane filtration separation to improve the performance of the label-free bioassay methods. Upon hybridization with the DNA/protein (carcinoembryonic antigen, CEA) target, the T-Hg2+-T hairpin structure was opened and Hg2+ was released; this initiated the cation exchange reaction between Hg2+ and CdTe QDs which released Cd2+ simultaneously. Subsequently, the free Cd2+ was separated by the filtration membrane without separating the CdTe QDs, which could then be separated from the sample matrices for the CVG-AFS/ICP-MS assay. Under the optimal conditions, this method possessed high sensitivity for DNA and CEA determination with limits of detection (LODs) of 0.2 nM and 0.2 ng mL-1, and linear dynamic ranges of 1-160 nM and 0.5-20 ng mL-1, respectively, and exhibited excellent DNA sequence specificity and protein selectivity. This method preserves the advantages of the label-free atomic spectrometric bioassay, and combined with the selective cation exchange reaction and simple filtration separation to improve the performance.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; DNA; DNA Probes; Humans; Limit of Detection; Mass Spectrometry; Mercury; Nucleic Acid Hybridization; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Tellurium

Breast cancer (BC) is the most frequent cancer that affects one in eight women worldwide. Recent advances in early cancer diagnosis anticipates more efficient treatment and prolong patient survival. MicroRNAs expression profiling plays a key role in diagnosis of cancer such as BC in early stages. For the first time we describe direct injection of hot electrons from plasmonic gold nanoparticles (AuNPs) to adsorbed water molecules with photoinduction of CdTe quantum dots (QDs) with emission wavelength at ~560 nm. As a result of hot electrons exiting from AuNPs with red color, gold cations (holes) are gradually discharged (AuNPs dissolution) leading to a colorless solution. Our group applied this phenomenon to propose a spectral method for miRNA recognition based on different responsive disaggregation and aggregation of CdTe QDs interacted with single strand DNA probes and DNA/RNA heteroduplex respectively resulting in a detection limit of 4.4 pM. This method has been applied also for the determination of miR-155 in the human breast carcinoma MCF-7 cells and normal human embryonic kidney cell line (HEK 293).

Topics: Cadmium Compounds; Fluorescent Dyes; Gold; HEK293 Cells; Humans; Limit of Detection; MCF-7 Cells; Metal Nanoparticles; MicroRNAs; Microscopy, Electron, Transmission; Quantum Dots; Solubility; Surface Plasmon Resonance; Tellurium

In this work, an innovative aptasensor based on electrochemiluminescence resonance energy transfer (ECL-RET) from CdTe quantum dots (QDs) to a cyanine dye (Cy5) fluorophore for the determination of Ochratoxin A (OTA) was fabricated. A strong cathodic ECL emission was obtained by the CdTe QDs modified glassy carbon electrode (GCE). After the immobilization with the capture DNA (cDNA) and the sequential hybridization with the probe DNA-modified Cy5 (pDNA, the aptamer of OTA), the ECL signal enhanced obviously through the ECL-RET. Meanwhile, the spectrum- and distance-related ECL enhancement effect was investigated. When the target OTA was in the presence, the pDNA-Cy5 molecules were released from the electrode surface owing to the specific interaction between OTA and aptamer, resulting in an evident decrease of ECL signal. Under optimal conditions, the developed aptasensor displayed the linear response toward OTA in the wide range of 0.0005-50 ng/mL with a low detection limit of 0.17 pg/mL. With the excellent selectivity, stability and repeatability, the strategy provided an efficient and universal method for the sensitive detection of target in practical application.

Topics: Aptamers, Nucleotide; Cadmium Compounds; Carbocyanines; Electrochemical Techniques; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Luminescence; Ochratoxins; Particle Size; Quantum Dots; Surface Properties; Tellurium; Zea mays

Zika virus (ZIKV) has been declared a public health emergency of international concern. ZIKV has been associated with some neurological disorders, and their long-term effects are not completely understood. The majority of the methods for ZIKV diagnosis are based on the detection of IgM antibodies, which are the first signs of immunological response. However, the detection of IgG antibodies can be an important approach for ZIKV past infection diagnosis, especially for pregnant women, helping the comprehension/treatment of this disease. There has been a growing interest in applying nanoparticles for efficient ZIKV or antibodies detection. Quantum dots (QD) are unique fluorescent semiconductor nanoparticles, highly versatile for biological applications. In the present study, we explored the special QD optical properties to develop an immunofluorescence assay for anti-ZIKV IgG antibodies detection. Anti-IgG antibodies were successfully conjugated with QDs and applied in a fluorescence sensing nanoplatform. After optimization using IgG antibodies, the conjugates were employed to detect anti-ZIKV IgG antibodies in polystyrene microplates sensitized with ZIKV envelope E protein. The nanoplatform was able to detect anti-ZIKV IgG antibodies in a concentration at least 100-fold lower than the amount expected for protein E immune response. Moreover, conjugates were able to detect the antibodies for at least 4 months. Thus, our results showed that this QDs-based fluoroimmunoplatform can be considered practical, simple and promising to detect Zika past infections and/or monitoring immune response in vaccine trials.

Topics: Antibodies, Anti-Idiotypic; Cadmium Compounds; Fluoroimmunoassay; Quantum Dots; Tellurium; Zika Virus

Topics: Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Gold; Humans; Limit of Detection; Luminescent Agents; Luminescent Measurements; Metal Nanoparticles; MicroRNAs; Nanospheres; Quantum Dots; Silicon Dioxide; Tellurium

Breast cancer which is the most commonly diagnosed cancer among women; have been known as a serious threat for health and life around the world. So development of an approach for early-stage diagnosis of breast cancer is vital. In this study, we designed a double aptamer-nanoparticle conjugates-based (DANP) complex for specific detection and visualization of MCF-7 cells using Mucin 1 (MUC 1) aptamer-conjugated gold nanoparticles (MUC1 apt - GNPs) and adenosine triphosphate (ATP) aptamer-conjugated CdTe quantum dots (ATP apt-QDs). The ATP apt-QDs was attached onto MUC1 apt - GNPs surface through Van der Waals forces and electrostatic interactions between ATP aptamer and GNPs leading to the formation of DANP complex. Atomic force microscopy asserted DANP complex formation. The imaging process was based on the recognition of MUC1 protein on the surface of MCF-7 cells by MUC1 aptamer and specific internalization of DANP complex into target cells (MCF-7). Existence of abundant amounts of ATP in lysosome led to release of ATP apt-QDs from the MUC1 apt-GNPs surface resulting in strong fluorescence emission. The flow cytometry analysis and fluorescence microscopy confirmed significant internalization of DANP complex into MCF-7 cells (target) in comparison with CHO cells (non-target). Based on the obtained results, the DANP complex possesses high potency for efficient detection and monitoring of breast cancer cells (MCF-7).

Topics: Animals; Aptamers, Nucleotide; Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; CHO Cells; Cricetulus; Female; Gold; Humans; MCF-7 Cells; Membrane Proteins; Metal Nanoparticles; Molecular Imaging; Mucin-1; Optical Imaging; Quantum Dots; Tellurium

Topics: Apoptosis; Cadmium Compounds; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Survival; DNA Damage; Glutathione; Humans; Liver Neoplasms; Membrane Potential, Mitochondrial; Mutagens; Oxidative Stress; Quantum Dots; Reactive Oxygen Species; Tellurium

This paper aimed to study the possible involvement of adenosine triphosphate-binding cassette (ABC) transporters in the detoxification of quantum dots (QDs) in human breast carcinoma (SK-BR-3) cells. The effects of QD sizes on such interactions were also evaluated. For this purpose, we used monodispersed MPA-COOH-CdTe QDs with different diameters (emission length at 560 and 625 nm, named as QD-560 and QD-625). Such QDs tended to accumulate in cells and cause significant toxicity. Using specific inhibitors of ABC transporters, the cellular accumulation and toxicity of QDs in SK-BR-3 cells were significantly affected. Moreover, treatment of QDs caused concentration- and time-dependent induction of ABC transporters. Furthermore, the induction effects of smaller QDs were found to be greater than larger ones at equivalent concentrations, suggesting a size-dependent recognition of substrates by ABC transporters. Overall, these results provided important support for the modulation of QDs toxicity by ABC transporters.

Topics: ATP-Binding Cassette Transporters; Biological Transport; Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; Female; Humans; Quantum Dots; Tellurium

A novel ternary-emission fluorescence sensor was proposed by post-imprinting mixing blue-/green-/red-emission bovine hemoglobin (BHb) imprinted polymers (b-MIPs, g-MIPs, and r-MIPs) at a proper ratio and realized the multiplexed and visual detection of BHb. The three MIPs were individually embedded with blue-emission 7-hydroxycoumarin, green-emission CdTe quantum dots (QDs), and red-emission CdTe/ZnS QDs. Upon interaction with BHb within 8 min, the fluorescence of CdTe and CdTe/ZnS QDs were simultaneously turned off, whereas the 7-hydroxycoumarin turned on the fluorescence intensity. Thereupon, the ratiometric fluorescence intensity of the ternary emission linearly varied within 0.025-3 μM BHb, accompanying the profuse fluorescence color evolution from yellowish green to yellow to salmon to plum to purple to finally blue. In comparison with the dual- or single-emission sensor, the ternary-emission fluorescence MIPs sensor provided a wider color variation covering the green-red-blue window for accurate naked-eye determination of BHb, as well as a lower detection limit down to 7.8 nM and a higher imprinting factor of 15.2. Moreover, the satisfactory recoveries of 99.25-111.7% in determining the spiked BHb in bovine urine samples, as well as the optical stability and post-imprinting construction convenience, indicated that the developed tricolor-emission fluorescence MIPs sensor provided an ideal alternative for rapid, sensitive, and visual determination of proteins in complicated samples.

Topics: Animals; Cadmium Compounds; Cattle; Color; Fluorescence; Fluorescent Dyes; Hemoglobins; Limit of Detection; Molecular Imprinting; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Zinc Sulfate

The application of quantum dots (QDs) is restricted by the biosafety issue. QDs contribute to the adverse effects of organisms probably because of the ability to induce oxidative stress via changing the activity of antioxidant enzyme, for example, superoxide dismutase (SOD). But the underlying molecular mechanisms still remain unclear. This study investigated the harmful effects of oxidative stress induced by mercaptopropionic acid capped CdTe QDs (MPA-CdTe QDs) on the mouse primary nephrocytes as well as the structure and function of SOD molecule and explored the underlying molecular mechanism. After 24-hour MPA-CdTe QD exposure, the activation level of extracellular regulated protein kinase (ERK) signaling pathway and cysteinyl-directed aspartate-specific proteases (Caspases) significantly increased, which led to the increasing level of reactive oxygen species (ROS) and cell apoptosis; the group pretreated with ROS scavenger N-acetyl-L-cysteine (NAC) significantly reduced the apoptotic cell percentage, indicating that ROS played a critical role in QD-induced cytotoxicity. Further molecular experiments showed that the interacting processes between the MPA-CdTe QDs and SOD were spontaneous which changed the conformation, secondary structure of SOD. The interaction significantly resulted in the tightening of polypeptide chains and the shrinkage of SOD, leading to the inhibition of molecular SOD activity. This study demonstrates the adverse effects of QDs, revealing their potential risk in biomedical applications.

Topics: 3-Mercaptopropionic Acid; Animals; Apoptosis; Cadmium Compounds; Calorimetry; Caspases; Cell Survival; Enzyme Activation; Kidney; Malondialdehyde; MAP Kinase Signaling System; Mice; Molecular Conformation; Oxidative Stress; Protein Structure, Secondary; Quantum Dots; Reactive Oxygen Species; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Superoxide Dismutase; Tellurium; Thermodynamics

Ratiometric fluorescent sensors have shown great prospect in chemical monitoring and recognition due to its high intuitiveness, accurateness, and visualization. In this work, the ratiometric fluorescent sensors, which includes a blue fluorescent Carbon quantum dots (CQDs) as internal standard material, and a red fluorescent boric acid-modified CdTe QDs as response signal. Then we choose dopamine (DA) as template, 3-phenylboronic acid (APBA) for functional monomers, tetraethyl orthosilicate (TEOS) for cross-linker to synthesize double ratio molecularly imprinted polymers (DR-MIPs) that can identify dopamine selectively and sensitively. The DR-MIPs has better capability of selective recognition, obvious anti-ion interference, rapid detection and good visualization. Furthermore, the unique DR-MIPs was proved as efficient visual sensors for determination of DA in human serum rapidly and efficiently. The DR-MIPs still displayed well accuracy, and the potential prospects of this smart sensor is clearly demonstrated in the context of modern clinical medicine.

Topics: Biosensing Techniques; Boronic Acids; Cadmium Compounds; Dopamine; Fluorescent Dyes; Humans; Limit of Detection; Molecular Imprinting; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Pig skin is a widely acknowledged surrogate for human skin for in vitro/ex vivo skin penetration studies with application for small molecules and nanosystems. We have investigated the influence of biological factors such as age and anatomical site on the penetration and distribution of nanoparticles (2.1 nm hydrophilic CdTe/CdS quantum dots: QDs) in adult pig skin (APS), weanling pig skin (WPS) and newborn pig skin (NBPS) at two different anatomical sites (ear and abdomen).. QDs in saline were applied to 1 × 1 cm2 skin (62.5 pmol/cm2) with 2-min finger rubbing using a standardized protocol. After 6- or 24-h incubation on Franz diffusion cells, tape stripping (×10) followed by manual follicular casting was conducted. Cadmium in QDs was quantified using inductively coupled plasma mass spectrometry for all samples. The presence of QDs in similarly treated skin samples was also captured using multiphoton tomography.. QDs were mainly localized in hair follicles after 6 and 24 h of exposure with no cadmium detected in the Franz cell receptor compartment regardless of pig age or anatomical site. The amount of QDs deposited in the follicles was similar at 6 h but higher on APS and WPS ears compared to NBPS ears at 24 h. This is associated with the high follicle density and small follicle diameter of the NBPS compared to the smaller density of much larger follicles on the APS. NBPS showed consistent QD distribution for ear and abdomen up to 24 h.. There is minimal penetration of QDs through pig skin. Density and diameter of follicles in association with age of pigs and application site influenced the amount of QDs deposited in follicles. The structure of the stratum corneum, follicle density and diameter of NBPS are similar to human skin suggesting that NBPS is an appropriate model for human skin in the evaluation of topical applications of a range of chemicals including nanosystems.

Topics: Abdomen; Aging; Animals; Cadmium Compounds; Ear; Nanoparticles; Quantum Dots; Skin; Swine; Tellurium; Time Factors

A fluorescent nanoprobe consisting of CdTe quantum dots (QDs) and coated with molecularly imprinted layers was prepared and successfully applied to the determination of norfloxacin (NOR) in seawater and wastewater samples. The 3-mercaptopropionic acid capped QDs were prepared and then covered with a protective silica shell. A molecularly imprinted layer was finally synthesized around the silanized QDs using 3-aminopropyltriethoxysilane as functional monomer and norfloxacin as the template. Compared with the non-imprinted polymer, the fluorescence of the nanoprobe with imprinted polymer (measured at excitation/emission wavelengths of 300/596 nm) is strongly reduced in the presence of NOR, and the imprinting factor is 8.8. Under the optimal experimental conditions, the detection limit of the nanoprobe is 0.18 μM, and response is linear between 0.5 - 28 μM of NOR. The relative standard deviation of the detection of NOR is <7.2%. In order to evaluate the practicality of the probe, wastewater and seawater samples spiked with norfloxacin were analyzed by this method, and recoveries ranged from 96.2 - 106.0%. Graphical abstract Schematic presentation and fluorescence spectrum of fluorescent nanoprobe with selectivity for norfloxacin (NOR). CdTe quantum dots (QDs) are used as fluorescent carriers, 3-aminopropyltriethoxysilane (APTES) as template molecules, tetraethyl orthosilicate (TEOS) as crosslinking agent, and aqueous ammonia as initiator.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Fluorescent Dyes; Limit of Detection; Molecular Imprinting; Norfloxacin; Polymers; Propylamines; Quantum Dots; Seawater; Silanes; Spectrometry, Fluorescence; Tellurium; Wastewater; Water Pollutants, Chemical

Recent work shows that Pockels effect and optics pump-probe measurement could be utilized as a novel method for 511 keV ionizing radiation photon detection for positron emission tomography (PET) which could potentially overcome the inherent physical limitation for coincidence time resolution of around 100 ps (Tao et al 2016 Phys. Med. Biol. 61 7600-22). In this paper, we embrace this observation and introduce a two-crossed-polarizers based setup to achieve similar detection concept, which is a simpler and more compact setup with comparable ionizing radiation detection capability as the setup used in the previously proposed work. We evaluated the performance of our experimental setup with Lithium Niobate (LiNbO

Topics: Cadmium Compounds; Optical Phenomena; Photons; Positron-Emission Tomography; Quantum Dots; Radiometry; Tellurium

In this work, an ultrasensitive photoelectrochemical (PEC) biosensor was proposed to detect nucleic acids on the basis of cascaded photoactive materials and triple-helix molecular switch. DNA sequence of human immunodeficiency virus type 1 (HIV-1) was chosen as the target DNA (T-DNA). Cascaded photoactive structure was formed via different sizes of CdTe quantum dots (QDs) sensitized ZnO nanorods (ZnO NRs), which was employed as a cascaded photoactive interface to amplify the photocurrent signal. A hairpin structure DNA (H-DNA) as capture probe was conjugated onto the photoactive interface through amide bond, and then a single-stranded DNA modified with gold nanoparticles labeled alkaline phosphatase (ALP-Au NPs-DNA) at each end was introduced to hybridize with the H-DNA to form a triple-helix conformation. The T-DNA detection was based on the photocurrent response change resulted from conformation change of the triple-helix molecule after hybridization with T-DNA. In the absence of T-DNA, the triple-helix molecule was in a closed state and the ALP of ALP-Au NPs-DNA could specifically catalyze the ascorbic acid 2-phosphate (AAP) to generate ascorbic acid (AA) as electron donors, which resulted in a significant photocurrent response due to the rapid electron transfer process. However, in the presence of T-DNA, the T-DNA hybridized with the ALP-Au NPs-DNA molecule, which caused triple-helix molecule in an opened state and compelled ALP-Au NPs-DNA away from the electrode surface, resulting in the absence of ALP which could catalyze AAP to generate AA. Subsequently, the photocurrent response significantly decreased. The proposed PEC biosensor not only had a wide detection range of 1fM-1nM and low detection limit (0.65 fM), but also showed excellent reproducibility, specificity and stability, which had great application prospect and opened up a new research method in the early clinical diagnosis and cancer research.

Topics: Base Sequence; Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; HIV-1; Humans; Metal Nanoparticles; Nanotubes; Nucleic Acid Hybridization; Quantum Dots; Tellurium

In this work, a novel three-dimensional cadmium telluride quantum dots-DNA nanoreticulation (3D CdTe QDs-DNA-NR) was used as a signal probe with the dual-legged DNA walker circular amplification as target conversion strategy to establish a pioneering electrochemiluminescence (ECL) biosensing strategy for ultrasensitive detection of microRNA-21 form cancer cells. Herein, such a 3D luminous nanomaterial with reticular structure not only supported abundant CdTe QDs to avoid the inner filter effect for obtaining a high ECL efficiency but also contained the hemin/G-quadruplex as coreaction accelerator in the 3D CdTe QDs-DNA-NR/S

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemistry; G-Quadruplexes; HeLa Cells; Hemin; Humans; Limit of Detection; Luminescent Measurements; MCF-7 Cells; MicroRNAs; Nanostructures; Quantum Dots; Tellurium

This study describes synthesis of N‑acetyl‑l‑cysteine-capped CdTe quantum dots (QDs) and investigates their interaction with plasma protein fibrinogen (FIB) and the structural changes of FIB. It is shown that the interaction of QDs with FIB is a spontaneous process and the major driving forces are van der Waals forces and hydrogen bonds. Multi-spectroscopic measurements show that the intrinsic fluorescence of FIB was quenched and secondary and tertiary structures were altered due to the interaction with QDs. In addition, the aggregation state of FIB was altered in the presence of QDs. Furthermore, the formed complexes of FIB with QDs reduced the cytotoxicity of QDs. The coating of FIB on QDs could lower intracellular QDs uptake and therefore result in less released cadmium ions and ROS productions. This study, therefore, might be helpful to the comprehensive understanding of QDs toxicity and provide evidence for assessing the safe application of nanoparticles.

Topics: Animals; Cadmium Compounds; Calorimetry; Cells, Cultured; Circular Dichroism; Fibrinogen; Hepatocytes; Hydrogen Bonding; Mice, Inbred C57BL; Protein Conformation; Protein Corona; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Thermodynamics

Quantum dots (QDs) are a unique class of nano-materials that have attractive potentials in biological and biomedical applications, and the concern on their biosafety is concomitantly increasing. The overproduction of reactive oxygen species (ROS) is considered to be one of the reasons that induce the in vitro QDs induced toxic response. However, the exact molecular pathways underlying these effects remain poorly clarified and few studies combine the molecular results with the cellular results to explore the cytotoxic effect of QDs. The aim of the present study was to evaluate the effect of mercaptopropionic acid (MPA) capped CdTe QDs on the structures and functions of two antioxidant enzymes, catalase (CAT) superoxide dismutase (SOD), and then associated with the cytotoxic effects of oxidative stress induced by MPA-CdTe QDs on mouse hepatocytes to define the toxic underlying mechanism. The molecular experiment results showed that the exposure of QDs significantly changed the conformation of CAT and SOD, and leading to the promotion of molecular CAT activity and the inhibition of molecular SOD activity. Meanwhile, the cellular experiment results demonstrated that exposure to QDs changed the activities of CAT and SOD in mouse primary hepatocytes, led to the break of redox balance and resulted in the oxidative stress and cell apoptosis. This study explores the effects of MPA- CdTe QDs to the CAT and SOD molecules and then demonstrates the subsequent QDs toxic effects at a cellular level, revealing their potential risk in biomedical applications.

Topics: Animals; Antioxidants; Apoptosis; Cadmium Compounds; Caspases; Catalase; Cells, Cultured; Circular Dichroism; Hepatocytes; Mice, Inbred C57BL; Oxidative Stress; Protein Conformation; Quantum Dots; Reactive Oxygen Species; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Sulfhydryl Compounds; Superoxide Dismutase; Tellurium

Water-soluble cadmium telluride quantum dots capped with 3-mercaptopropionic acid were synthesized and further modified with 3-aminophenylboronic acid to form boronic acid-functionalized quantum dots (QDs). Under excitation at 350 nm, the modified QDs display yellow fluorescence with a peak at 566 nm. On exposure to copper(II), the fluorescence of the QDs is quenched. Under optimal conditions, fluorescence drops linearly in the 0.01 to 20 μM Cu(II) concentration range, and the detection limit is 7.6 nM. This fluorescent probe was applied to the determination of Cu(II) in spiked human serum and water samples and gave satisfactory results. Graphical abstract Schematic presentation of the principle for fluorometrice detection of copper(II) based on the use of boronic acid-functionalized cadmium telluride quantum dots (CdTe QDs).

Topics: Boronic Acids; Cadmium Compounds; Copper; Fluorescent Dyes; Humans; Limit of Detection; Quantum Dots; Rivers; Spectrometry, Fluorescence; Tellurium; Water Pollutants, Chemical

To enhance the power of untargeted detection, a "turn-off" fluorescent probe with double quantum dots (QDs) was developed and coupled with chemometrics for rapid detection of multiple adulterants in an herbal (Rhus chinensis Mill., RCM) honey. The double water-soluble ZnCdSe-CdTe QDs have two separate and strong fluorescent peaks, which can be quenched by honey and extraneous adulterants with varying degrees. Class models of pure RCM honey samples collected from 6 different producing areas (n = 122) were developed using one-class partial least squares (OCPLS). Four extraneous adulterants, including glucose syrup, sucrose syrup, fructose syrup, and glucose-fructose syrup were added to pure honey samples at the levels of 0.5% to 10% (w/w). As a result, the OCPLS model using the second-order derivative (D2) spectra could detect 1.0% (w/w) of different syrups in RCM honey, with a sensitivity of 0.949. The double water-soluble QDs, which can be adjusted for analysis of other water-soluble food samples, has largely extended the capability of traditional fluorescence and will provide a potentially more sensitive and specific analysis method for food frauds.

Topics: Cadmium Compounds; China; Fluorescent Dyes; Food Contamination; Glucose; Honey; Least-Squares Analysis; Models, Statistical; Quantum Dots; Selenium Compounds; Sensitivity and Specificity; Solubility; Spectrometry, Fluorescence; Sucrose; Tellurium; Zinc Compounds

A nanocomposite fluorescent probe based on fluorescence quenching was fabricated and utilized for the detection of lomefloxacin. The fabricated probe integrated the high sensitivity of quantum dots, the excellent selectivity of molecularly imprinted polymer and the high adsorption affinity of graphene oxide and polyaniline. The probe exhibited good sensitivity, high specificity, and rapidity for lomefloxacin monitoring. Fluorescence emission was reduced linearly by lomefloxacin from 0.10 to 50.0 μg L

Topics: Aniline Compounds; Animals; Cadmium Compounds; Chickens; Eggs; Fluorescent Dyes; Fluoroquinolones; Food Contamination; Graphite; Limit of Detection; Milk; Nanocomposites; Poultry Products; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Tellurium

Conventional atomic spectrometry biosensors usually require labeling and separation of signaling molecules. Visual assays have direct and effective characteristics; however, they have poor accuracy. We intended to improve the analytical performance of our previous work and simplify the experimental operation while maintaining the advantages of simple operation and low cost. Herein, we describe the development of a visual, chemical vapor generation-atomic fluorescence spectrometry (CVG-AFS) and inductively coupled plasma-mass spectrometry (ICP-MS) three-mode method for the analysis of nucleic acids via CdTe quantum dot (QD)-assisted selective cation exchange reaction and enzyme-free strand displacement amplification. This work mainly utilized the ability of CdTe QDs to selectively differentiate free Hg

Topics: Base Sequence; Cadmium Compounds; DNA; DNA Probes; Humans; Limit of Detection; Mass Spectrometry; Mercury; Nucleic Acid Amplification Techniques; Nucleic Acid Hybridization; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Based on the high sensitivity and stable fluorescence of CdTe quantum dots (QDs) in conjunction with a specific DNA aptamer, the authors describe an aptamer-based fluorescence assay for the determination of Salmonella Typhimurium. The fluorescence detection and quantification of S. Typhimurium is based on a magnetic separation system, a combination of aptamer-coated Fe3O4 magnetic particles (Apt-MNPs) and QD-labeled ssDNA2 (complementary strand of the aptamer). Apt-MNPs are employed for the specific capture of S. Typhimurium. CdTe QD-labeled ssDNA2 was used as a signaling probe. Simply, the as-prepared CdTe QD-labeled ssDNA2 was first incubated with the Apt-MNPs to form the aptamer-ssDNA2 duplex. After the addition of S. Typhimurium, they could specifically bind the DNA aptamer, leading to cleavage of the aptamer-ssDNA2 duplex, accompanied by the release of CdTe QD-labeled DNA. Thus, an increased fluorescence signal can be achieved after magnetic removal of the Apt-MNPs. The fluorescence of CdTe QDs (λexc/em = 327/612 nm) increases linearly in the concentration range of 10 to 1010 cfu•mL-1, and the limit of detection is determined to be 1 cfu•mL-1. The detection process can be performed within 2 h and is successfully applied to the analysis of spiked food samples with good recoveries from 90% to 105%.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Ferrosoferric Oxide; Fluorescence; Humans; Quantum Dots; Salmonella Infections; Salmonella typhimurium; Tellurium

Quantum dots have generated great interest because of their optical properties, both to life sciences and electronics applications. However, possible risks to the environment associated with these nanoparticles are still under investigation. The present study aimed to evaluate the toxicity of suspensions of cadmium telluride (CdTe) quantum dots to Biomphalaria glabrata mollusks, a very sensitive aquatic environmental bioindicator for physical and chemical agents. Toxicity was examined by using embryos and adult mollusks as well as hemocytes. The distribution of cadmium in the organs of adults was also assessed. Effects of the stabilizing agent of the quantum dots were also evaluated. Animals were exposed to suspensions of quantum dots for 24 h, at concentrations varying from 1.2 to 20 nM for embryos and from 50 to 400 nM for adult mollusks. Results showed that suspensions of quantum dots induced malformations and mortality in embryos and mortality in adults, depending on the concentration applied. In the cytotoxicity study, hemocyte apoptosis was observed in adults exposed to the highest concentration of quantum dots applied as well as to the stabilizing agent. Cell binucleation and micronucleus frequencies were not significative. Bioaccumulation evaluation revealed that quantum dots targeted the digestive gland (hepatopancreas). Taken together, outcomes suggested that specific nano-effects related directly not only to composition but also to the aggregation of quantum dots may be mediating the observed toxicity. Thus B. glabrata was determined to be a very sensitive species for interpreting possible nano-effects in aquatic environments. Environ Toxicol Chem 2019;38:2128-2136. © 2019 SETAC.

Topics: Animals; Apoptosis; Bioaccumulation; Biomphalaria; Cadmium Compounds; Embryo, Nonmammalian; Hemocytes; Quantum Dots; Suspensions; Tellurium; Toxicity Tests, Acute

Using a simple fluorogenic reaction and the inner filter effect, a label-free ratiometric method for biothiol detection is developed. The reaction between dopamine and resorcinol can generate azamonardine with strong fluorescence. Since the absorption spectrum of azamonardine overlaps with the excitation spectrum of the mercaptopropionic acid-stabilized CdTe quantum dots (MPA-CdTe QDs), the emission of QDs can be quenched via the inner filter effect in the presence of azamonardine. Biothiols can inhibit the above fluorogenic reaction, resulting in the weakening of the fluorescence of azamonardine and the recovery of the emission of MPA-CdTe QDs. The fluorescence intensity ratio of azamonardine to MPA-CdTe QDs can be used to detect biothiols. This approach exhibited a linear trend to the biothiol concentrations in the range of 2 μM to 12 μM, with a limit of detection of 0.6 μM (S/N = 3). This ratiometric analysis strategy was further applied to detect biothiols in human serum samples, showing their great application potentials in real biological samples. The constructed method is simple, easy to prepare, and low-cost.

Topics: Cadmium Compounds; Cysteine; Dopamine; Fluorescent Dyes; Glutathione; Homocysteine; Humans; Limit of Detection; Quantum Dots; Resorcinols; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) are engineered nanoparticles (NPs) of semiconductor structure that possess unique optical and electronic properties and are widely used in biomedical applications; however, their risks are not entirely understood. This study investigated the tissue distribution and toxic effects of cadmium telluride quantum dots (CdTe-QDs) in male BALB/c mice for up to 1 week after single-dose intravenous injections. CdTe-QDs were detected in the blood, lung, heart, liver, spleen, kidney, testis and brain. Most CdTe-QDs accumulated in the liver, followed by the spleen and kidney. At high doses, exposure to CdTe-QDs resulted in mild dehydration, lethargy, ruffled fur, hunched posture, and body weight loss. Histological analysis of the tissues, upon highest dose exposures, revealed hepatic hemorrhage and necrotic areas in the spleen. The sera of mice treated with high doses of CdTe-QDs showed significant increases in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin levels, as well as a reduction in albumin. CdTe-QD exposure also led to a reduced number of platelets and elevated total white blood cell counts, including monocytes and neutrophils, serum amyloid A, and several pro-inflammatory cytokines. These results demonstrated that the liver is the main target of CdTe-QDs and that exposure to CdTe-QDs leads to hepatic and splenic injury, as well as systemic effects, in mice. By contrast, cadmium chloride (CdCl

Topics: Alanine Transaminase; Albumins; Animals; Aspartate Aminotransferases; Bilirubin; Cadmium Chloride; Cadmium Compounds; Injections, Intravenous; Male; Mice; Mice, Inbred BALB C; Nanoparticles; Quantum Dots; Tellurium; Tissue Distribution

In recent years, a ratiometric electrochemical method has been investigated due to its ability to effectively reduce the background electrical signals via the introduction of an internal calibration mechanism, which has great practical significance in the detection of mycotoxins in foods. Herein, we report a ratiometric electrochemical aptasensor based on two semiconductor quantum dots (i.e. CdTe and PbS QDs) for the detection of aflatoxin B1 (AFB1). The aptasensor was fabricated by immobilizing PbS QD-coated silica hybrid spheres (SiO2@PbS) onto CdTe QD-modified Fe3O4@SiO2 (Fe3O4@SiO2/CdTe) surface through biorecognition between the aptamer and complementary DNAs, where PbS QDs acted as external signal labels and CdTe QDs acted as internal reference labels. In the presence of AFB1, the aptamer connected to SiO2@PbS preferred to form an aptamer/AFB1 complex, which brought about the separation of SiO2@PbS linked with the CdTe QDs; with the addition of more AFB1 to the solution, the amount of SiO2@PbS present on the Fe3O4@SiO2/CdTe surface reduced. After several steps of endonuclease cleavage, magnetic separation, and dissolution with acid, the square wave voltammetry signals of Pb2+ and Cd2+ maintained an inverse relationship with the target content based on the SWV stripping measurements; the proposed method had the wide linear range of 5 pg mL-1-50 ng mL-1 and the determination limit of 4.5 pg mL-1 (S/N = 3) and was applied for the detection of AFB1 in peanuts. The proposed aptasensor has an important practical significance for the development of food safety.

Topics: Aflatoxin B1; Aptamers, Nucleotide; Arachis; Biosensing Techniques; Cadmium Compounds; DNA, Complementary; Electrochemical Techniques; Lead; Limit of Detection; Nucleic Acid Hybridization; Quantum Dots; Reproducibility of Results; Semiconductors; Silicon Dioxide; Sulfides; Tellurium

With the continuing development of beamlines for macromolecular crystallography (MX) over the last few years providing ever higher X-ray flux densities, it has become even more important to be aware of the effects of radiation damage on the resulting structures. Nine papers in this issue cover a range of aspects related to the physics and chemistry of the manifestations of this damage, as observed in both MX and small-angle X-ray scattering (SAXS) on crystals, solutions and tissue samples. The reports include measurements of the heating caused by X-ray irradiation in ruby microcrystals, low-dose experiments examining damage rates as a function of incident X-ray energy up to 30 keV on a metallo-enzyme using a CdTe detector of high quantum efficiency as well as a theoretical analysis of the gains predicted in diffraction efficiency using these detectors, a SAXS examination of low-dose radiation exposure effects on the dissociation of a protein complex related to human health, theoretical calculations describing radiation chemistry pathways which aim to explain the specific structural damage widely observed in proteins, investigation of radiation-induced damage effects in a DNA crystal, a case study on a metallo-enzyme where structural movements thought to be mechanism related might actually be radiation-damage-induced changes, and finally a review describing what X-ray radiation-induced cysteine modifications can teach us about protein dynamics and catalysis. These papers, along with some other relevant literature published since the last Journal of Synchrotron Radiation Radiation Damage special issue in 2017, are briefly summarized below.

Topics: Cadmium Compounds; Crystallization; DNA; DNA Damage; Scattering, Small Angle; Synchrotrons; Tellurium; X-Ray Diffraction; X-Rays

Using X-ray energies higher than those normally used (5-15 keV) for macromolecular X-ray crystallography (MX) at synchrotron sources can theoretically increase the achievable signal as a function of dose and reduce the rate of radiation damage. In practice, a major stumbling block to the use of higher X-ray energy has been the reduced quantum efficiency of silicon detectors as the X-ray energy increases, but hybrid photon-counting CdTe detectors are optimized for higher X-ray energies, and their performance has been steadily improving. Here the potential advantages of using higher incident beam energy together with a CdTe detector for MX are explored, with a particular focus on the advantages that higher beam energies may have for MX experiments with microbeams or microcrystals. Monte Carlo simulations are presented here which for the first time include the efficiency responses of some available X-ray detectors, as well as the possible escape of photoelectrons from the sample and their entry from surrounding material. The results reveal a `sweet spot' at an incident X-ray energy of 26 keV, and show a greater than factor of two improvement in diffraction efficiency at this energy when using microbeams and microcrystals of 5 µm or less.

Topics: Cadmium Compounds; Crystallography, X-Ray; Dose-Response Relationship, Radiation; Monte Carlo Method; Tellurium; X-Rays

Breast computed tomography (BCT) is an emerging application of X-ray tomography in radiological practice. A few clinical prototypes are under evaluation in hospitals and new systems are under development aiming at improving spatial and contrast resolution and reducing delivered dose. At the same time, synchrotron-radiation phase-contrast mammography has been demonstrated to offer substantial advantages when compared with conventional mammography. At Elettra, the Italian synchrotron radiation facility, a clinical program of phase-contrast BCT based on the free-space propagation approach is under development. In this paper, full-volume breast samples imaged with a beam energy of 32 keV delivering a mean glandular dose of 5 mGy are presented. The whole acquisition setup mimics a clinical study in order to evaluate its feasibility in terms of acquisition time and image quality. Acquisitions are performed using a high-resolution CdTe photon-counting detector and the projection data are processed via a phase-retrieval algorithm. Tomographic reconstructions are compared with conventional mammographic images acquired prior to surgery and with histologic examinations. Results indicate that BCT with monochromatic beam and free-space propagation phase-contrast imaging provide relevant three-dimensional insights of breast morphology at clinically acceptable doses and scan times.

Topics: Cadmium Compounds; Female; Humans; Mammography; Microscopy, Phase-Contrast; Synchrotrons; Tellurium; X-Ray Microtomography

To meet the need for high-throughput immunoassays, many multiplex fluorescent immunoassays have been proposed. Most of them need different kinds of fluorescent label indicators during the test. In this work, a novel indirect ELISA-inspired dual-channel fluorescent immunoassay based on 3-mercaptopropionic acid capped CdTe/ZnS quantum dots (QDs) was constructed. The ELISA wells were coated with two kinds of antigen-QD complex. When the primary antibodies were present in a sample, they mediated the binding of a secondary antibody-DNA-gold nanoparticle complex to the antigen-QD complex. Then the gold nanoparticles quenched the fluorescence of the QDs and a decrease in fluorescence intensity was observed. Thus, the amount of primary antibody could be estimated from the decrease of fluorescence intensity. Owing to the wide absorption range and the relatively narrow emission band of the QDs, the dual-channel fluorescent immunoassay system could work at the same excitation wavelength and the emission wavelengths of each channel had no interference. As a result, two different kinds of primary antibody could be detected at the same time in one ELISA well, which simplified the operation and greatly improved the efficiency. Besides, only one type of secondary antibody needs to be added to the prepared microtiter plates, which further simplified the operation during the detection procedure. This dual-channel fluorescent immunoassay system will provide new insights into high-throughput immunodetection. Graphical abstract.

Topics: Cadmium Compounds; Enzyme-Linked Immunosorbent Assay; Fluorescent Antibody Technique; Metal Nanoparticles; Microscopy, Electron, Transmission; Quantum Dots; Sulfides; Tellurium; Zinc Compounds

Detection and imaging RNAs in live cells is in high demand. Methodology for such a purpose is still a challenge, particularly for single RNA detection and imaging in live cells. In this study, a type of quantum dot (QD) nanobeacon with controllable valencies was constructed by precisely conjugating the black hole quencher (BHQ1) and phosphorothioate comodified DNA onto CdTe:Zn

Topics: Cadmium Compounds; Cell Line; DNA; HIV-1; Humans; Microscopy, Confocal; Optical Imaging; Quantum Dots; RNA; RNA, Viral; Tellurium

Topics: Ammonium Compounds; Cadmium Compounds; Fluorides; Humans; Monte Carlo Method; Positron-Emission Tomography; Quantum Dots; Radiography; Selenium Compounds; Tellurium; Zinc

With the widespread contamination of ochratoxin A (OTA), it is of significant importance for detecting OTA in foods and traditional Chinese medicine (TCM). In this study, a novel label-free fluorescent aptasensor utilizing the interaction between OTA-triggered antiparallel G-quadruplex and (N-methyl-4-pyridy) porphyrin (TMPyP) for the rapid and sensitive determination of OTA was established. The fluorescence of CdTe quantum dots (QDs) could be quenched by TMPyP. In the presence of analyte (OTA), the aptamer could recognize OTA and transform from a random coil to the antiparallel G-quadruplex. The interaction between G-quadruplex and TMPyP could release CdTe QDs from TMPyP, and thus recover the fluorescence of CdTe QDs. Under optimized conditions, the detection limit of the designed aptasensor was 0.16 ng mL

Topics: Aptamers, Nucleotide; Astragalus Plant; Cadmium Compounds; Fluorescence; G-Quadruplexes; Ochratoxins; Porphyrins; Quantum Dots; Tellurium

End of life photovoltaic panels of different technologies (poly crystalline Si, amorphous Si, and CdTe) were treated mechanically in pilot scale by single shaft shredder minimizing the production of fine fractions below 0.4 mm (<18% weight). Grounded material was sieved giving: an intermediate fraction (0.4-1 mm) of directly recoverable glass (18% weight); a coarse fraction (which should be further treated for encapsulant removal), and fine fractions of low-value glass (18%), which can be treated by leaching for the removal of metal impurities. Encapsulant removal from coarse fraction was successfully performed by solvent treatment using cyclohexane at 50 °C for 1 h giving high-grade glass (52% weight), which can be reused for panel production. Experimental results of solvent treatment were compared with those from thermal treatment by economic analysis and Life Cycle Assessment, denoting in both cases the advantages of solvent treatment in recovering high-value glass.

Topics: Cadmium Compounds; Glass; Quantum Dots; Recycling; Silicon; Solvents; Tellurium

Rapid and efficient detection of microRNA (miRNA) of breast cancer 1 gene mutation (BRCA1) at their earliest stages is one of the crucial challenges in cancer diagnostics. In this study, a highly-sensitive electrochemical DNA biosensor was fabricated by double signal amplification (DSA) strategy for the detection of ultra-trace miRNA of BRCA1. In the presence of target miRNA of BRCA1, the well-matched RNA-DNA duplexes were specifically recognized by double-strand specific nuclease (DSN), and the DNA part of the duplexes were then cleaved and miRNAs were released to trigger another following cycle, which produced a primarily amplified signal by such a cyclic enzymatic signal amplification (CESA). Then triple-CdTe quantum dot labelled DNA nanocomposites (3-QD@DNA NC) was selectively hybridized with the cleaved DNA probe on the electrode and produced multiply amplified signals. The biosensor exhibited a high sensitivity for the detection of miRNA of BRCA1 in concentrations ranging from 5 aM to 5 fM, and its detection limit of 1.2 aM was obtained, which is two or three orders of magnitude lower than those by single signal amplification strategy such as CESA or QD-labeled DNA probes. The as-prepared biosensor was successfully used to detect the miRNA of BRCA1 in human serum samples with acceptable stability, good reproducibility, and good recovery. The proposed DNA biosensor based on double signal amplification strategy provided a feasible, rapid, and sensitive platform for early clinical diagnosis and practical applications.

Topics: Biosensing Techniques; Cadmium Compounds; Deoxyribonucleases; Electrochemical Techniques; Genes, BRCA1; Humans; Immobilized Nucleic Acids; MicroRNAs; Mutation; Nanocomposites; Quantum Dots; Tellurium

Topics: Antibodies, Bacterial; Cadmium Compounds; Chitosan; Enterobacter aerogenes; Escherichia coli; Fluorometry; Immunoassay; Lab-On-A-Chip Devices; Luminescent Measurements; Magnetics; Microfluidic Analytical Techniques; Nanoparticles; Quantum Dots; Salmonella enteritidis; Spectrometry, Fluorescence; Staining and Labeling; Tellurium

The purpose of this study was to determine the toxicity of two different sources of cadmium, i.e. CdCl

Topics: 3-Mercaptopropionic Acid; Adsorption; Araceae; Biomass; Cadmium Chloride; Cadmium Compounds; Environmental Monitoring; Fresh Water; Glutathione; Models, Theoretical; Quantum Dots; Tellurium; Water Pollutants, Chemical

Ag

Topics: Cadmium Compounds; Circular Dichroism; Humans; Quantum Dots; Serum Albumin, Human; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Static Electricity; Tellurium

We herein report an aqueous synthesis of gelatin stabilized CdTe/CdS/ZnS (CSSG) core/double shell quantum dots (QDs) with improved biocompatibility. The as-synthesized QDs were characterized by ultraviolet-visible (UV-vis) and photoluminescence (PL) spectroscopic techniques, x-ray diffraction technique (XRD), x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The CSSG QDs revealed high photoluminescence quantum yield (PLQY) with excellent stability over a period of one year and retained 90% of its initial PLQY without any aggregation or precipitation under ambient condition. The cell viability study conducted on HeLa, cervical cancer cell lines indicated that the gelatin stabilization effectively decreased the QDs cytotoxicity by about 50%. The CSSG QDs were conjugated with transferrin (Tf) for the efficient delivery to the cancer cells followed by fluorescence imaging. The results showed that the CSSG QDs illuminates the entire cell which renders the QDs as cell labeling markers. The gelatin stabilized core/double shell QDs are potential candidates for long time fluorescent bio-imaging.

Topics: Biocompatible Materials; Cadmium Compounds; Cell Survival; Gelatin; HeLa Cells; Humans; Luminescent Measurements; Molecular Probes; Optical Imaging; Quantum Dots; Receptors, Transferrin; Sulfides; Tellurium; Transferrin; Zinc Compounds

Cellular and brain metabolism of dopamine can be correlated with a number of neurodegenerative disorders, our study was to explore a simple and efficient method to detect dopamine in real samples.. A new quantum dots (CdTe QDs) could be prepared using the hydrothermal method, the electrochemical biosensor was established by dropping CdTe QDs on the surface of glassy carbon electrode (GCE).. The CdTe QDs/GCE exhibited the excellent electrochemical catalytic activity toward dopamine (DA) with good stability and high sensitivity in presence of interfering substances. The detection limit of DA was calculated by differential pulse voltammetry (DPV) as low as 0.3 μmol L. In this paper, the proposed electrochemical biosensor could be effectively used for the direct and rapid detection of DA in human serum and urine samples.

Topics: Cadmium Compounds; Carbon; Dopamine; Electrochemical Techniques; Electrodes; Glass; Humans; Limit of Detection; Linear Models; Quantum Dots; Reproducibility of Results; Tellurium

We describe the preparation and validation of a novel lateral flow immunoassay test for the detection of human heart fatty acid binding protein (hFABP). Water-soluble CdTe quantum dots (QDs) were selected as the fluorescent label and were linked covalently to anti-hFABP antibodies. Upon conjugation, the secondary structure of the anti-hFABP was preserved and the fluorescence quantum yield of the CdTe QDs increased. The labelled antibodies were transferred to the immunoassay test strip and the antigen-antibody reaction was successfully performed. This evidenced the preserved antibody activity of QD-labelled anti-hFABP towards hFABP, and provided a rapid means for the quantitation of hFABP in human serum within the range of 0-160ng ∙ ml

Topics: Animals; Blood Chemical Analysis; Cadmium Compounds; Calibration; Fatty Acid-Binding Proteins; Humans; Immunoassay; Limit of Detection; Linear Models; Quantum Dots; Tellurium

Quantum dots (QDs) are semiconducting nanocrystals with unique optical properties. When coated with shell/capping, QDs are not deleterious to cells and organisms. However, when QDs are retained in the cellular environment for a certain period of time, their coatings may be degraded, yielding "naked" QDs. Although some studies have documented the acute effects of cadmium telluride (CdTe) QDs in various cell lines, however, to our knowledge, there are no published studies on the chronic effects of CdTe QDs in normal lung cells. In this study, we therefore sought to study the effects of CdTe QDs of various particle sizes on their cytotoxicity and carcinogenicity in normal human bronchial epithelial cells (BEAS-2B). A total of three particle sizes of CdTe QD with emission maximum at 520, 580, and 730 nm were employed (abbreviated as 520Q, 580Q, and 730Q, respectively). Our results indicated that acute exposure to 520Q (∼2.04 nm in diameter) and 580Q (∼3.24 nm in diameter) elicited dose-dependent cytotoxicity; while acute exposure to 730Q (∼5.40 nm in diameter) elicited negligible cytotoxicity in BEAS-2B cells. Notably, chronic exposure to CdTe QD of all three tested particle sizes induced BEAS-2B cell transformation as evidenced by enhanced cell migration and anchorage-independent growth on soft agar. Taken together, our findings suggest that CdTe QDs are potent human lung carcinogens.

Topics: Acute Disease; Alveolar Epithelial Cells; Bronchial Neoplasms; Cadmium Compounds; Cell Line; Cell Survival; Cell Transformation, Neoplastic; Chronic Disease; Dose-Response Relationship, Drug; Humans; Particle Size; Quantum Dots; Tellurium; Toxicity Tests

Tremendous research efforts have been dedicated to fabricating high-quality Zn-doped CdTe quantum dots (QDs) for any potential biomedical applications. In particular, the correlation of issues regarding how QDs interact with DNA is of greatest importance. Herein, a pH-responsive study of the interactions between CdTe:Zn

Topics: Cadmium Compounds; DNA; Electrochemical Techniques; Hydrogen Bonding; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Zinc

We present the performance of a highly granulated 3D detector module for PET, consisting of a stack of pixelated CdTe detectors. Each detector module has 2 cm  ×  2 cm  ×  2 cm of CdTe material, subdivided into 4000 voxels, where each voxel has size 1 mm  ×  1 mm  ×  2 mm and is connected to its own read-out electronics via a BiSn solder ball. Each read-out channel consists of a preamp, a discriminator, a shaper, a peak-and-hold circuit and a 10 bits SAR ADC. The preamp has variable gain where at the maximum gain the ADC resolution is equivalent to 0.7 keV. Each ASIC chip reads 100 CdTe pixel channels and has one TDC to measure the time stamp of the triggered events, with a time resolution of less than 1 ns. With the bias voltage set at  -250 V mm

Topics: Cadmium Compounds; Humans; Phantoms, Imaging; Photons; Positron-Emission Tomography; Quantum Dots; Tellurium

Fluorescence resonance energy transfer (FRET) system based on functionalized CdTe-guanine and AuNPs-cytosine bioconjugates for the model nucleobase - guanine detection was developed. Thioglycolic acid coated cadmium telluride quantum dots (QDs) conjugated with guanine and sodium 3-mercapto-1-propanesulfonate stabilized gold nanoparticles (AuNPs) capped by cytosine were obtained and fully characterized. Successful formation of the materials was confirmed by UV-Vis, fluorescence and FTIR spectroscopies. Composition of the conjugates was also characterized with elemental analysis and XPS. By employing a guanine-cytosine interaction the bonding between these complementary nucleobases attached to the nanoparticles leads to the formation of QDs-guanine-AuNPs-cytosine assembly, with the size about 7 nm as demonstrated using atomic force microscopy. That enables an effective FRET from functionalized QDs to AuNPs since both, the required distance and the spectral characteristics of donor-acceptor pair were secured. However, it was shown that in the presence of guanine-model molecule which inhibits the interaction between conjugated QDs and AuNPs the FRET is efficiently hampered. Thus monitoring the changes in the restoring fluorescence signal allows to assay the free guanine concentration. Importantly, we have demonstrated the sensitivity and selectivity of the obtained FRET-based system towards guanine. Moreover, in order to confirm the feasibility of the proposed material for nucleobase detection in the real biological samples the developed nanoparticles were also evaluated under simulated urine conditions. The presented strategy of FRET-based conjugated system preparation might be easily used for the development of another nucleobases selective detection and thus opens many possibilities for the determination of biomolecules in the real samples.

Topics: Cadmium Compounds; Cytosine; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Gold; Guanine; Metal Nanoparticles; Molecular Structure; Particle Size; Quantum Dots; Surface Properties; Tellurium

A novel detection platform with high malathion specificity has been developed, which operates based on the signal response in the fluorescence of CdTe@CdS quantum dots (QDs). The designed nanoprobe comprises of QDs, poly(N-(3-guanidinopropyl)methacrylamide) homopolymer (PGPMA) and malathion specific aptamer. The interaction of aptamer with malathion results in switching off of the fluorescence signal of the probe due to the availability of the cationic polymer, which causes quenching of the QDs. However, in the absence of malathion, the polymer interacts with the aptamer, via electrostatic interactions thereby rendering the fluorescence of QDs unaffected. The assay exhibited excellent sensitivity towards malathion with a detection limit of 4pM. A logarithmic correlation was observed in a wide range of malathion concentrations from 0.01nm to 1μM, facilitating the potential of proposed assay in the quantitative determination of the analyte of interest. The selectivity of the designed probe was confirmed in the presence of various pesticides, commonly employed in agricultural fields.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Fluorescence; Malathion; Polymers; Quantum Dots; Selenium Compounds; Tellurium

Viscoelastic properties are central for gels and other materials. Simultaneously, high storage and loss moduli are difficult to attain due to their contrarian requirements to chemical structure. Biomimetic inorganic nanoparticles offer a promising toolbox for multiscale engineering of gel mechanics, but a conceptual framework for their molecular, nanoscale, mesoscale, and microscale engineering as viscoelastic materials is absent. Here we show nanoparticle gels with simultaneously high storage and loss moduli from CdTe nanoparticles. Viscoelastic figure of merit reaches 1.83 MPa exceeding that of comparable gels by 100-1000 times for glutathione-stabilized nanoparticles. The gels made from the smallest nanoparticles display the highest stiffness, which was attributed to the drastic change of GSH configurations when nanoparticles decrease in size. A computational model accounting for the difference in nanoparticle interactions for variable GSH configurations describes the unusual trends of nanoparticle gel viscoelasticity. These observations are generalizable to other NP gels interconnected by supramolecular interactions and lead to materials with high-load bearing abilities and energy dissipation needed for multiple technologies.

Topics: Biomimetic Materials; Cadmium Compounds; Glutathione; Hydrogels; Mechanical Phenomena; Nanoparticles; Tellurium; Viscoelastic Substances

We describe a simple and effective strategy to construct a molecular imprinting ratiometric fluorescence sensor (MIR sensor) for the visual detection of bovine hemoglobin (BHb) used as a model protein. The sensor was prepared by simply mixing the solution of green and red CdTe quantum dots (QDs), which were embedded in core-shell structured molecularly imprinted polymers and silica nanoparticles, respectively. The resultant hybrid MIR sensor can selectively bind with BHb and thus quench the fluorescence of the green QDs, while the red QDs wrapped with silica are insensitive to BHb with the fluorescence intensity unchanged. As a result, a continuous obvious fluorescence color change from green to red can be observed by naked eyes, with the detection limit of 9.6 nM. Moreover, the MIR sensor was successfully applied to determine BHb in bovine urine samples with satisfactory recoveries at three spiking levels ranging from 95.7 to 101.5%, indicating great potential application for detecting BHb in real samples. This strategy of using different fluorescence emission materials incorporated to construct a ratiometric fluorescence sensor is reasonable and convenient, which can be extended to the preparation of other ratiometric fluorescence systems for targeted analytes.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Cattle; Fluorescent Dyes; Hemoglobins; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Molecular Imprinting; Quantum Dots; Reproducibility of Results; Sensitivity and Specificity; Silicon Dioxide; Spectrometry, Fluorescence; Surface Properties; Tellurium

It is commonly true that a diluted colloidal suspension is more stable over time than a concentrated one because dilution reduces collision rates of the particles and therefore delays the formation of aggregates. However, this generalization does not apply for some engineered ligand-coated nanoparticles (NPs). We observed the opposite relationship between stability and concentration of NPs. We tested 4 different types of NPs: CdSe-11-mercaptoundecanoic acid, CdTe-polyelectrolytes, Ag-citrate, and Ag-polyvinylpyrrolidone. The results showed that dilution alone induced aggregation and subsequent sedimentation of the NPs that were originally monodispersed at very high concentrations. Increased dilution caused NPs to progressively become unstable in the suspensions. The extent of the dilution impact on the stability of NPs is different for different types of NPs. We hypothesize that the unavoidable decrease in free ligand concentration in the aqueous phase following dilution causes detachment of ligands from the suspended NP cores. The ligands attached to NP core surfaces must generally approach exchange equilibrium with free ligands in the aqueous phase; therefore, ligand detachment and destabilization are expected consequences of dilution. More studies are necessary to test this hypothesis. Because the stability of NPs determines their physicochemical and kinetic behavior including toxicity, dilution-induced instability needs to be understood to realistically predict the behavior of engineered ligand-coated NPs in aqueous systems. Environ Toxicol Chem 2018;37:1301-1308. © 2018 SETAC.

Topics: Cadmium Compounds; Dynamic Light Scattering; Fatty Acids; Filtration; Hydrodynamics; Ligands; Metal Nanoparticles; Nanotechnology; Quantum Dots; Silver; Sulfhydryl Compounds; Suspensions; Tellurium; Time Factors

Quantum dots (QDs) are a class of engineered nanoparticles (ENPs) with several biomedical, industrial and commercial applications. However, their metabolism and detoxification process in aquatic invertebrates and environmental health hazards remain unclear. This study investigate the transcriptional changes of metallothioneins (MTs) isoforms (mt10IIIa and mt20IV) induced by CdTe QDs, in comparison with its dissolved counterpart, in the marine mussel Mytilus galloprovincialis. Mussels were exposed to CdTe QDs and to the same Cd concentration (10 µg Cd L

Topics: Animals; Cadmium Compounds; Gills; Metallothionein; Mytilus; Oxidative Stress; Protein Isoforms; Quantum Dots; Tellurium; Transcription, Genetic; Water Pollutants, Chemical

Up to now, the colloidal gold labeling immunochromatographic test strip is a mature and applicable technology. However, different from the conventional gold nanoparticle, quantum dot (QD) possesses larger specific surface area and better biocompatibility. So, as a novel nanomaterial, QD is capable of assembling more biomolecule which could enhance the sensitivity and accuracy of strips by rationality. Besides, strand displacement amplification was drawn into our test strips in this paper, this assumption made HIV-DNA recycling many times and converting it to plentiful QD-dsDNA (double-stranded deoxyribonucleic acid), where after these nano-structures would be captured by test zone. Meanwhile, the suggested scheme eliminated the hook effect owing to the target drop out of the incorporation on test zone, and any nucleotide sequence or substance which has aptamers can work as the target, such as carcinoembryonic antigen or mycotoxin. This assay realized the detection limit of as low as 0.76 pM (S/N = 3) and the detection range of 1 pM to 10 nM. In the end, we made use of this fluorescent lateral flow assay strips with great reproducibility for detecting HIV-DNA in human serum, that attested this method could be applied to practical application prospectively.

Topics: Biosensing Techniques; Cadmium Compounds; DNA, Viral; Equipment Design; Fluorescent Dyes; HIV; HIV Infections; Humans; Limit of Detection; Quantum Dots; Reagent Strips; Reproducibility of Results; Tellurium

Photon-counting detectors using CdTe or CZT substrates are promising candidates for future CT systems but suffer from a number of nonidealities, including charge sharing and pulse pileup. By increasing the pixel size of the detector, the system can improve charge sharing characteristics at the expense of increasing pileup. The purpose of this work is to describe these considerations in the optimization of the detector pixel pitch.. The transport of x rays through the CdTe substrate was simulated in a Monte Carlo fashion using GEANT4. Deposited energy was converted into charges distributed as a Gaussian function with size dependent on interaction depth to capture spreading from diffusion and Coulomb repulsion. The charges were then collected in a pixelated fashion. Pulse pileup was incorporated separately with Monte Carlo simulation. The Cramér-Rao lower bound (CRLB) of the measurement variance was numerically estimated for the basis material projections. Noise in these estimates was propagated into CT images. We simulated pixel pitches of 250, 350, and 450 microns and compared the results to a photon counting detector with pileup but otherwise ideal energy response and an ideal dual-energy system (80/140 kVp with tin filtration). The modeled CdTe thickness was 2 mm, the incident spectrum was 140 kVp and 500 mA, and the effective dead time was 67 ns. Charge summing circuitry was not modeled. We restricted our simulations to objects of uniform thickness and did not consider the potential advantage of smaller pixels at high spatial frequencies.. At very high x-ray flux, pulse pileup dominates and small pixel sizes perform best. At low flux or for thick objects, charge sharing dominates and large pixel sizes perform best. At low flux and depending on the beam hardness, the CRLB of variance in basis material projections tasks can be 32%-55% higher with a 250 micron pixel pitch compared to a 450 micron pixel pitch. However, both are about four times worse in variance than the ideal photon counting detector. The optimal pixel size depends on a number of factors such as x-ray technique and object size. At high technique (140 kVp/500 mA), the ratio of variance for a 450 micron pixel compared to a 250 micron pixel size is 2126%, 200%, 97%, and 78% when imaging 10, 15, 20, and 25 cm of water, respectively. If 300 mg/cm. The detector pixel size is an important design consideration in CdTe detectors. Smaller pixels allow for improved capabilities at high flux but increase charge sharing, which in turn compromises spectral performance. The optimal pixel size will depend on the specific task and on the charge shaping time.

Topics: Cadmium Compounds; Humans; Monte Carlo Method; Tellurium; Tomography, X-Ray Computed

Fluorescent "turn-off" sensors based on double quantum dots (QDs) has attracted increasing attention in the detection of many materials due to their properties such as more useful information, higher fluorescence efficiency and stability compared with the fluorescent "turn-off" sensors based on single QDs. In this work, highly sensitive and specific method for recognition of 53 different famous green teas was developed based on the fluorescent "turn-off" model with water-soluble ZnCdSe-CdTe double QDs. The fluorescence of the two QDs can be quenched by different teas with varying degrees, which results in the differences in positions and intensities of two peaks. By the combination of classic partial least square discriminant analysis (PLSDA), all the green teas can be discriminated with high sensitivity, specificity and a satisfactory recognition rate of 100% for training set and 100% for prediction set, respectively. The fluorescent "turn-off" sensors based on the single QDs (either ZnCdSe QDs or CdTe QDs) coupled with PLSDA were also employed to recognize the 53 famous green teas with unsatisfactory results. Therefore, the fluorescent "turn-off" sensors based on the double QDs is more appropriate for the large-class-number classification (LCNC) of green teas. Herein, we have demonstrated, for the first time, that so many kinds of famous green teas can be discriminated by the "turn-off" model of double QDs combined with chemometrics, which has largely extended the capability of traditional fluorescence and chemometrics, as well as exhibits great potential to perform LCNC in other practical applications.

Topics: Cadmium Compounds; Discriminant Analysis; Fluorescence; Fluorescent Dyes; Quantum Dots; Selenium Compounds; Spectrometry, Fluorescence; Tea; Tellurium; Water; Zinc

Unfolded protein response (UPR) and endoplasmic reticulum (ER)-phagy are essential for cell homeostasis. Quantum dots (QDs), which have been widely used for biomedical applications, can accumulate in the kidney tissues and may cause renal dysfunction. However, the molecular mechanism of QDs-induced nephrotoxicity is still obscure. The present study was aimed to elucidate the role and mechanism of UPR and ER-phagy in QDs-induced nephrotoxicity. Herein, human embyronic kidney (HEK) cells were exposed to 15, 30, 45, and 60 nM cadmium telluride (CdTe)-QDs for 12 and 24 h. And CdTe-QDs (30-60 nM) inhibited the HEK cell viability. The clathrin-dependent endocytosis was determined as the main pathway of CdTe-QDs cellular uptake. Within cells, CdTe-QDs disrupted ER ultrastructure and induced UPR and FAM134B-dependent ER-phagy. Blocking UPR with inhibitors or siRNA rescued the FAM134B-dependent ER-phagy, which was triggered by CdTe-QDs. Moreover, suppression of UPR or FAM134B-dependent ER-phagy restored the cell vability. In vivo, mice were intravenously injected with 8 and 16 nmol/kg body weight CdTe-QDs for 24 h. Kidney was shown as one of highest distributed organs of CdTe-QDs, resulting in renal dysfunction, as well as UPR and FAM134B-dependent ER-phagy in it. Thus, for the first time, we demonstrated that ER-phagy can be triggered by nanomaterials both in vitro and in vivo. In addition, blocking of UPR and ER-phagy showed protective effects against CdTe-QDs-induced toxicity in kideny cells. Notably, a secreted alkaline phosphatase reporter gene system has been developed as a sensitive and rapid method for evaluating the ER quality under the exposure of nanomaterials.

Topics: Animals; Cadmium Compounds; Cell Line; Endocytosis; Endoplasmic Reticulum; Homeostasis; Humans; Intracellular Signaling Peptides and Proteins; Kidney; Membrane Proteins; Mice; Mice, Inbred BALB C; Neoplasm Proteins; Quantum Dots; Tellurium; Unfolded Protein Response

Quantum dots are the semiconductor nanocrystals having unique optical and electronic properties. Quantum dots are category of fluorescent labels utilized for biological tagging, biosensing, bioassays, bioimaging and in vivo imaging as they exhibit very small size, signal brightness, photostability, tuning of light emission range, longer photoluminescence decay time as compared to organic dyes. In this work, we have synthesized and characterized mercaptopropionic acid capped cadmium telluride quantum dots (MPA-CdTe QDs) using hydrothermal method. The study further reports fluorescence intensity stability of quantum dots suspended in different buffers of varying concentration (1-100 mM), stored at various photophysical conditions. Fluorescence intensity values were reduced with increase in buffer concentration. When the samples were stored at room temperature in ambient light condition the quantum dots suspended in different buffers lost the fluorescence intensity after day 15 (except TRIS II). Fluorescence intensity values were found stable for more than 30 days when the samples were stored in dark condition. Samples stored in refrigerator displayed modest fluorescence intensity even after 300 days of storage. Thus, storage of MPA-CdTe QDs in refrigerator may be the suitable choice to maintain its fluorescence stability for longer time for further application.

Topics: 3-Mercaptopropionic Acid; Buffers; Cadmium Compounds; Fluorescence; Fluorescent Dyes; Quantum Dots; Tellurium

In this study, semiconducting organic polymer dots (Pdots) and inorganic quantum dots (Qdots) were first utilized to construct the organic-inorganic nanodots heterojunction for the photoelectrochemical (PEC) bioanalysis application. Specifically, n-type CdS Qdots, p-type CdTe Qdots, and tetraphenylporphyrin (TPP)-doped poly[(9,9-dioctylfluorenyl-2,7-diyl)- co-(1,4-benzo-{2,1',3}-thiadazole)] (PFBT) Pdots were fabricated, and their energy levels, that is, their valence band (VB)/conduction band (CB) or lowest unoccupied molecular orbital (LUMO)/highest occupied molecular orbital (HOMO) values, were also determined. Then, these nanodots were integrated to construct four types of p-n and p-p organic-inorganic nanodots heterojunctions, that is, CdS Qdots/TPP-doped PFBT Pdots, TPP-doped PFBT Pdots/CdS Qdots, CdTe Qdots/TPP-doped PFBT Pdots, and TPP-doped PFBT Pdots/CdTe Qdots, on the transparent glass electrode. Upon light irradiation, four heterojunctions exhibited different PEC behaviors with some having prominent photocurrent enhancement. With the model molecule l-cysteine (l-cys) as target, the proposed PEC sensor exhibited good performances. In brief, this work presents the first semiconducting organic-inorganic nanodots heterojunction for PEC bioanalysis application, which could be easily used as a general platform for future PEC bioanalysis building. Besides, it is expected to inspire more interest in the design, development, and implementation of various organic-inorganic heterojunctions for advanced PEC bioanalysis in the future.

Topics: Cadmium Compounds; Electrochemical Techniques; Fluorenes; Light; Photochemical Processes; Polymers; Porphyrins; Quantum Dots; Semiconductors; Sulfides; Tellurium

Single-photon-counting (SPC) and spectroscopic x-ray detectors are under development in academic and industry laboratories for medical imaging applications. The spatial resolution of SPC and spectroscopic x-ray detectors is an important design criterion. The purpose of this article was to extend the cascaded systems approach to include a description of the spatial resolution of SPC and spectroscopic x-ray imaging detectors.. A cascaded systems approach was used to model reabsorption of characteristic x rays, Coulomb repulsion, and diffusion in SPC and spectroscopic x-ray detectors. In addition to reabsorption, diffusion, and Coulomb repulsion, the model accounted for x-ray conversion to electron-hole (e-h) pairs, integration of e-h pairs in detector elements, electronic noise, and energy thresholding. The probability density function (PDF) describing the number of e-h pairs was propagated through each stage of the model and was used to derive new theoretical expressions for the large-area gain and modulation transfer function (MTF) of CdTe SPC x-ray detectors, and the energy bin sensitivity functions and MTFs of CdTe spectroscopic detectors. Theoretical predictions were compared with the results of MATLAB-based Monte Carlo (MC) simulations and published data. Comparisons were also made with the MTF of energy-integrating systems.. Under general radiographic conditions, reabsorption, diffusion, and Coulomb repulsion together artificially inflate count rates by 20% to 50%. For thicker converters (e.g. 1000 μm) and larger detector elements (e.g. 500 μm pixel pitch) these processes result in modest inflation (i.e. ∼10%) in apparent count rates. Our theoretical and MC analyses predict that SPC MTFs will be degraded relative to those of energy-integrating systems for fluoroscopic, general radiographic, and CT imaging conditions. In most cases, this degradation is modest (i.e., ∼10% at the Nyquist frequency). However, for thicker converters, the SPC MTF can be degraded by up to 25% at the Nyquist frequency relative to EI systems. Additionally, unlike EI systems, the MTF of spectroscopic systems is strongly dependent on photon energy, which results in energy-bin-dependent spatial resolution in spectroscopic systems.. The PDF-transfer approach to modeling signal transfer through SPC and spectroscopic x-ray imaging systems provides a framework for understanding system performance. Application of this approach demonstrated that charge sharing artificially inflates the SPC image signal and degrades the MTF of SPC and spectroscopic systems relative to energy-integrating systems. These results further motivate the need for anticharge-sharing circuits to mitigate the effects of charge sharing on SPC and spectroscopic x-ray image quality.

Topics: Cadmium Compounds; Monte Carlo Method; Photons; Radiography; Tellurium; X-Rays

A highly sensitive fluorescence detection probe was developed by tailoring plastic antibodies on the external surface of aqueous soluble quantum dots (QDs). The target was Myoglobin (Myo), a cardiac biomarker that quenched the intrinsic fluorescent emission of cadmium telluride (CdTe) QDs capped with mercaptopropionic acid (CdTe-MPA-QDs). The QDs were incubated with the target protein and further modified with a molecularly-imprinted polymer (MIP) produced by radical polymerization of acrylamide and bisacrylamide. The main physical features of the materials were assessed by electron microscopy, dynamic light scattering (DLS), UV/Vis spectrophotometry and spectrofluorimetry. The plastic antibodies enabled Myo rebinding into the QDs with subsequent fluorescence quenching. This QD-probe could detect Myo concentrations from 0.304 to 571 pg/ml (50.6 fM to 95 pM), with a limit of detection of 0.045 pg/ml (7.6 fM). The proposed method was applied to the determination of Myo concentrations in synthetic human serum. The results obtained demonstrated the ability of the modified-QDs to determine Myo below the cut-off values of myocardial infarction. Overall, the nanostructured MIP-QDs reported herein displayed quick responses, good stability and sensitivity, and high selectivity for Myo, offering the potential to be explored as new emerging sensors for protein detection in human samples.

Topics: Acrylic Resins; Biomarkers; Cadmium Compounds; Humans; Molecular Imprinting; Myocardial Infarction; Myoglobin; Quantum Dots; Sensitivity and Specificity; Tellurium

An ultrasensitive photoelectrochemical (PEC) aptasensor for lead ion (Pb

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Disulfides; Electrochemical Techniques; G-Quadruplexes; Ions; Lead; Manganese; Molybdenum; Nanocomposites; Particle Size; Photochemical Processes; Quantum Dots; Sulfides; Surface Properties; Tellurium

Inter-pixel communication and anti-charge sharing (ACS) technologies have been introduced to photon counting detector (PCD) systems to address the undesirable charge sharing problem. In addition to improving the energy resolution of PCD, ACS may also influence other aspects of PCD performance such as detector multiplicity (i.e. the number of pixels triggered by each interacted photon) and detective quantum efficiency (DQE). In this work, a theoretical model was developed to address how ACS impacts the multiplicity and zero-frequency DQE [DQE(0)] of PCD systems. The work focused on cadmium telluride (CdTe)-based PCD that often involves the generation and transport of K-fluorescence photons. Under the parallel cascaded systems analysis framework, the theory takes both photoelectric and scattering effects into account, and it also considers both the reabsorption and escape of photons. In a new theoretical treatment of ACS, it was considered as a modified version of the conventional single pixel (i.e. non-ACS) mode, but with reduced charge spreading distance and K-fluorescence travel distance. The proposed theoretical model does not require prior knowledge of the detailed ACS implementation method for each specific PCD, and its parameters can be experimentally determined using a radioisotope without invoking any Monte-Carlo simulation. After determining the model parameters, independent validation experiments were performed using a diagnostic x-ray tube and four different polychromatic beams (from 50 to 120 kVp). Both the theoretical and experimental results demonstrate that ACS increased the first and second moments of multiplicity for a majority of the x-ray energy and threshold levels tested, except when the threshold level was much lower than the x-ray energy level. However, ACS always improved DQE(0) at all energy and threshold levels tested.

Topics: Cadmium Compounds; Humans; Models, Theoretical; Monte Carlo Method; Photons; Quantum Dots; Radiography; Tellurium

Semiconductor quantum dots (QDs), especially those containing cadmium, have undergone marked improvements and are now widely used nanomaterials in applicable biological fields. However, great concerns exist regarding their toxicity in biomedical applications. Because of the lack of sufficient data regarding the toxicity mechanism of QDs, this study aimed to evaluate the cytotoxicity of three types of QDs: CdTe QDs, high yield CdTe QDs, and CdTe/CdS core/shell QDs on two human breast cancer cell lines MDA-MB468 and MCF-7.. The breast cancer cells were treated with different concentrations of QDs, and cell viability was evaluated via MTT assay. Hoechst staining was applied for observation of morphological changes due to apoptosis. Apoptotic DNA fragmentation was visualized by the agarose gel electrophoresis assay. Flow cytometric annexin V/propidium iodide (PI) measurement was used for apoptosis detection.. A significant decrease in cell viability was observed after QDs treatment ( p < 0.05). Apoptotic bodies and chromatin condensation was observed by Hoechst staining. DNA fragmentation assay demonstrated a DNA ladder profile in the exposed cells and also annexin V/PI flow cytometry confirmed apoptosis in a dose-dependent manner.. Our results revealed that CdTe, high yield CdTe, and CdTe/CdS core/shell QDs induce apoptosis in breast cancer cell lines in a dose-dependent manner. This study would help realizing the underlying cytotoxicity mechanism, at least partly, of CdTe QDs and may provide information for the development of nanotoxicology and safe use of biological applications of QDs.

Topics: Apoptosis; Cadmium Compounds; Cell Line, Tumor; Cell Survival; DNA Fragmentation; Humans; MCF-7 Cells; Quantum Dots; Tellurium

Herein, we successfully devised a novel photoelectrochemical (PEC) platform for ultrasensitive detection of adenosine by target-triggering cascade multiple cycle amplification based on the silver nanoparticles-assisted ion-exchange reaction with CdTe quantum dots (QDs). In the presence of target adenosine, DNA s1 is released from the aptamer and then hybridizes with hairpin DNA (HP1), which could initiate the cycling cleavage process under the reaction of nicking endonuclease. Then the product (DNA b) of cycle I could act as the "DNA trigger" of cycle II to further generate a large number of DNA s1, which again go back to cycle I, thus a cascade multiple DNA cycle amplification was carried out to produce abundant DNA c. These DNA c fragments with the cytosine (C)-rich loop were captured by magnetic beads, and numerous silver nanoclusters (Ag NCs) were synthesized by AgNO

Topics: Adenosine; Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Humans; Ion Exchange; Limit of Detection; Metal Nanoparticles; Nucleic Acid Hybridization; Photochemical Processes; Quantum Dots; Silver; Tellurium

The currently utilized ligand fishing for bioactive molecular screening from complex matrixes cannot perform imaging screening. Here, we developed a new solid-phase ligand fishing coupled with an in situ imaging protocol for the specific enrichment and identification of heat shock protein 90 (Hsp 90) inhibitors from Tripterygium wilfordii, utilizing a multiple-layer and microkernel-based mesoporous nanostructure composed of a protective silica coating CdTe quantum dot (QD) core and a mesoporous silica shell, i.e., microkernel-based mesoporous (SiO

Topics: Cadmium Compounds; Cell Survival; Dose-Response Relationship, Drug; Fluorescent Dyes; HSP90 Heat-Shock Proteins; Humans; MCF-7 Cells; Nanoparticles; Optical Imaging; Particle Size; Porosity; Silicon Dioxide; Structure-Activity Relationship; Surface Properties; Tellurium; Tripterygium

As a promising biolabeling biomaterials, quantum dots (QDs) present a great potential. However, the toxicity of QDs to organisms has attracted wide attention. In our research, we introduced an in vitro method to study the molecular mechanisms for the structure and activity alterations of Candida rugosa lipase (CRL) with the binding of 3-mercaptopropionic acid-capped CdTe QDs. Multiple spectroscopic methods, isothermal titration calorimetry, and enzyme activity measurements were used in this paper. QDs statically quenched the intrinsic fluorescence of CRL with the quenching constant decreases from 2.46 × 10

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Candida; Lipase; Protein Binding; Proteins; Quantum Dots; Spectrum Analysis; Tellurium; Water

Suitable fluorophores are the core of fluorescence imaging. Among the most exciting, yet controversial, labels are quantum dots (QDs) with their unique optical and chemical properties, but also considerable toxicity. This hinders QDs applicability in living systems. Surface chemistry has a profound impact on biological behavior of QDs. This study describes a two-step synthesis of QDs formed by CdTe core doped with Schiff base ligand for lanthanides [Ln (Yb. Microwave-assisted synthesis resulted in water-soluble nanocrystals with high colloidal and fluorescence stability with quantum yields of 40.9-58.0%. Despite induction of endocytosis and cytoplasm accumulation of Yb- and TbQDs, surface doping resulted in significant enhancement in cytocompatibility when compared to the un-doped CdTe QDs. Furthermore, only negligible antimigratory properties without triggering formation of reactive oxygen species were found, particularly for TbQDs. Ln-doped QDs did not cause observable hemolysis, adsorbed only a low degree of plasma proteins onto their surface and did not possess significant genotoxicity. To validate the applicability of Ln-doped QDs for in vitro visualization of receptor status of living cells, we performed a site-directed conjugation of antibodies towards immuno-labeling of clinically relevant target-human norepinephrine transporter (hNET), over-expressed in neuroendocrine tumors like neuroblastoma. Immuno-performance of modified TbQDs was successfully tested in distinct types of cells varying in hNET expression and also in neuroblastoma cells with hNET expression up-regulated by vorinostat.. For the first time we show that Ln-doping of CdTe QDs can significantly alleviate their cytotoxic effects. The obtained results imply great potential of Ln-doped QDs as cytocompatible and stable fluorophores for various bio-labeling applications.

Topics: Cadmium Compounds; Cell Line, Tumor; Fluorescent Dyes; Humans; Lanthanoid Series Elements; Microwaves; Optical Imaging; Quantum Dots; Schiff Bases; Single-Cell Analysis; Surface Properties; Tellurium

In this paper, a novel chemiluminescence (CL) system was introduced based on the use of CdTe quantum dots (QDs) with the mixture solutions of fluorescein and potassium periodate (KIO

Topics: Cadmium Compounds; Catechols; Fluorescein; Kinetics; Limit of Detection; Luminescence; Luminescent Agents; Luminescent Measurements; Periodic Acid; Potassium Compounds; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Water

Quantum dots (QDs) have widespread application in many fields such as medicine and electronics. The need for understanding the potentially harmful side effects of these materials becomes clear. In this study, the toxicity of cadmium telluride quantum dots (CdTe-QDs) and bulk Cd

Topics: Animals; Cadmium; Cadmium Compounds; Cadmium Poisoning; Dose-Response Relationship, Drug; Endoplasmic Reticulum; Injections, Intraperitoneal; Kidney; Liver; Male; Metabolomics; Mice; Organ Specificity; Oxidative Stress; Particle Size; Principal Component Analysis; Quantum Dots; Random Allocation; Spleen; Surface Properties; Tellurium; Testis; Toxicity Tests, Chronic

Recently, the increasing number of bio-safety assessments on cadmium-containing quantum dots (QDs) suggested that they could lead to detrimental effects on the central nervous system (CNS) of living organisms, but the underlying action mechanisms are still rarely reported. In this study, whole-transcriptome sequencing was performed to analyze the changes in genome-wide gene expression pattern of rat hippocampus after treatments of cadmium telluride (CdTe) QDs with two sizes to understand better the mechanisms of CdTe QDs causing toxic effects in the CNS. We identified 2095 differentially expressed genes (DEGs). Fifty-five DEGs were between the control and 2.2 nm CdTe QDs, 1180 were between the control and 3.5 nm CdTe QDs and 860 were between the two kinds of CdTe QDs. It seemed that the 3.5 nm CdTe QD exposure might elicit severe effects in the rat hippocampus than 2.2 nm CdTe QDs at the transcriptome level. After bioinformatics analysis, we found that most DEG-enriched Gene Ontology subcategories and Kyoto Encyclopedia of Genes and Genomes pathways were related with the immune system process. For example, the Gene Ontology subcategories included immune response, inflammatory response and T-cell proliferation; Kyoto Encyclopedia of Genes and Genomes pathways included NOD/Toll-like receptor signaling pathway, nuclear factor-κB signaling pathway, tumor necrosis factor signaling pathway, natural killer cell-mediated cytotoxicity and T/B-cell receptor signaling pathway. The traditional toxicological examinations confirmed the systemic immune response and CNS inflammation in rats exposed to CdTe QDs. This transcriptome analysis not only revealed the probably molecular mechanisms of CdTe QDs causing neurotoxicity, but also provided references for the further related studies.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Databases, Genetic; Gene Expression Profiling; Gene Regulatory Networks; Hippocampus; Immunity; Male; Particle Size; Quantum Dots; Rats, Wistar; Tellurium; Transcriptome

It is now common practice in environmental life cycle assessment (LCA) to conduct sensitivity analyses to identify critical parameters and prioritize further research. Typical approaches include variation of input parameters one at a time to determine the corresponding variation in characterized midpoints or normalized and weighted end points. Generally, those input parameters that cause the greatest variations in output criteria are accepted as the most important subjects of further investigation. However, in comparative LCA of emerging technologies, the typical approach to sensitivity analysis may misdirect research and development (R&D) toward addressing uncertainties that are inconsequential or counterproductive. This paper presents a novel method of sensitivity analysis for a decision-driven, anticipatory LCA of three emerging photovoltaic (PV) technologies: amorphous-Si (a-Si), CdTe and ribbon-Si. Although traditional approaches identify metal depletion as critical, a hypothetical reduction of uncertainty in metal depletion fails to improve confidence in the environmental comparison. By contrast, the novel approach directs attention toward marine eutrophication, where uncertainty reduction significantly improves decision confidence in the choice between a-Si and CdTe. The implication is that the novel method will result in better recommendations on the choice of the environmentally preferable emerging technology alternative for commercialization.

Topics: Cadmium Compounds; Quantum Dots; Tellurium; Uncertainty

The excellent optical properties of CdTe quantum dots (QDs) make researchers realize their value on the application of biomedicine, especially neuroscience, as an advanced fluorescent probe. Thus, it is important to evaluate the biosafety of CdTe QDs on the central nervous system (CNS). Our previous studies have conducted a systematic biosafety evaluation of CdTe QDs on the CNS and found several toxic endpoints, one of which is the inflammation on the rat hippocampus, but their underlying mechanism remains unclear. In this study, when BV2 microglial cells were exposed to CdTe QDs with doses <20 nM, there was no obviously adverse effect. However, 40 nM CdTe QDs exposure could significantly activate the BV2 cells and increase the pro-inflammatory cytokine IL-1ß secretion. Molecular biology analyses suggested that both TLR2/MyD88/NF-κB pathway and NLRP3 inflammasome participated in the CdTe QD-induced IL-1ß secretion. The former served as the first signal for pro-IL-1ß expression, while the later played a role on the maturation of pro-IL-1ß into IL-1ß. The results, taken together, demonstrated that MPA-modified CdTe QDs exposure with a high concentration was capable of activating microglial cells and promoting IL-1ß secretion, which was highly correlated with the activations of both TLR2/MyD88/NF-κB pathway and ROS-induced NLRP3 inflammasome. These findings provide some mechanistic insights regarding the neuroinflammatory responses to cadmium-based QDs.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Cytokines; Inflammasomes; Mice; Microglia; Myeloid Differentiation Factor 88; NLR Family, Pyrin Domain-Containing 3 Protein; Quantum Dots; Reactive Oxygen Species; Signal Transduction; Tellurium; Toll-Like Receptors

Usually, photoelectrochemical (PEC) assays were devoted to the direct modification of photoactive materials on sensing interface, thereby producing high initial signal and unneglected background noise, which could further result in low sensitivity and restricted detection limit during the detection of targets. In this work, a PEC biosensor with near-zero background noise was established for ultrasensitive microRNA-141 (miRNA-141) detection based on DNA tetrahedron (TET) as nanocarrier for efficient immobilization of CdTe quantum dots (QDs)-Methylene Blue (MB) (TET-QDs-MB complex) as signal probe. First, CdTe QDs as PEC signal indicator was bound to the TET through DNA hybridizations. Then, massive MB as PEC signal enhancer was attached to DNA duplex of the TET immobilized with CdTe QDs via intercalation. Thereafter, the as-prepared TET-QDs-MB complex was considered as an efficient PEC signal probe owing to its excellent photovoltaic properties, thereby avoiding direct modification of photoactive materials on sensing interface and producing a near-zero background noise to improve the sensitivity of this PEC biosensor. Besides, the detection sensitivity could be further improved with the help of the duplex specific nuclease (DSN) enzyme-assisted target cycling amplification strategy. The proposed PEC biosensor performs a wide linear range from 50 aM to 50 pM with a low detection limit of 17 aM for miRNA-141, paving a new and promising horizon for highly accurate and ultrasensitive monitoring of multifarious analytes such as proteins, DNAs, and miRNAs in bioanalysis and disease diagnosis.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemistry; HeLa Cells; Humans; Limit of Detection; Methylene Blue; MicroRNAs; Models, Molecular; Molecular Conformation; Nanostructures; Photochemical Processes; Quantum Dots; Signal-To-Noise Ratio; Tellurium

Metallothionein (MT) plays the important role in the detoxification of heavy metals, protection against oxidative compounds and as a prognostic marker in the development of tumors. It is important to find selective, stable and sensitive tools and probes to evaluate the presence of MT in biological fluids or tissues. QDs linked with ligands such as peptides or small molecules are a promising tool for selective, fast, and sensitive tagging and imaging in medicine. In previous findings, the authors proved the possibility of interaction with QDs (particularly with CdTe) and analyzed the stability of the formed complexes between CdTe and MT during incubation over time. Following that, an initial analysis of the interactions between CdTe quantum dots (QDs) and human metallothionein (MT) was performed. Complexes of mercaptosuccinic acid-covered CdTe QDs + MT were investigated using fluorescence intensity changes along a timeline, quenching analysis, stability interpretation based on zeta potential, and quenching intensity. Based on the preliminary results, it appears as though the possible interactions depend on the size of the CdTe QDs. Additionally, the formation of complexes between CdTe and human MT likely depends mostly on structural changes and conformational reorganization rather than on electrostatic interactions. Both types of interactions are responsible for complex creation and stabilization.

Topics: Cadmium Compounds; Fluorescence; Humans; Metallothionein; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium

Semiconductor quantum dots (QDs) are a new nano-material, and their unique optical properties have become a focal point of research in both academia and industry. In this study, we studied photoluminescence (PL) intermittence (or 'blinking') behaviors of individual QDs prepared with different chiral ligands by using single molecule microscopy and single molecule fluorescence correlation spectroscopy (FCS). We found that the chirality of N-isobutyryl-d/l-cysteine (D/L-NIC) as surface stabilizers significantly influences PL blinking behaviors of cadmium telluride (CdTe) QDs synthesized in aqueous solution. The 'on time' distribution and the power-law exponent analyses show that the D-NIC more efficiently suppresses the blinking of QDs over L-NIC. Ensemble spectroscopies verfied that the remarkably-different blinking behaviors of QDs induced by ligand chirality were attributed to the different number of chiral ligands bound in the surface of QDs.

Topics: Cadmium Compounds; Ligands; Luminescence; Quantum Dots; Semiconductors; Tellurium

Gene editing is an important genetic engineering technique that enables gene manipulation at the molecular level. It mainly relies on engineered nucleases of biological origin, whose precise functions cannot be replicated in any currently known abiotic artificial material. Here, we show that chiral cysteine-modified CdTe nanoparticles can specifically recognize and, following photonic excitation, cut at the restriction site GAT'ATC (' indicates the cut site) in double-stranded DNA exceeding 90 base pairs, mimicking a restriction endonuclease. Although photoinduced reactive oxygen species are found to be responsible for the cleavage activity, the sequence selectivity arises from the affinity between cysteine and the conformation of the specific DNA sequence, as confirmed by quantum-chemical calculations. In addition, we demonstrate non-enzymatic sequence-specific DNA incision in living cells and in vivo using these CdTe nanoparticles, which may help in the design of abiotic materials for gene editing and other biological applications.

Topics: Cadmium Compounds; DNA; Genetic Engineering; Nanoparticles; Photochemical Processes; Semiconductors; Tellurium

There are now over a thousand nano-containing products on the market and the antibacterial properties of some nanomaterials has created interest in their use as cleaning agents, biocides and disinfectants. Engineered nanomaterials (ENMs) are being released into the environment and this raises concerns about their effects on microbes in the receiving ecosystems. This study evaluated the bacterial toxicity of a wide range of nanomaterials with different surface coatings on Escherichia coli K-12 MG1655. The minimum inhibitory concentration (MIC) assay, which quantifies the threshold for growth inhibition in suspensions of bacteria, was used to rank the toxicity of silver (Ag), cupric oxide (CuO), cadmium telluride (CdTe) quantum dots, titanium dioxide (TiO

Topics: Anti-Bacterial Agents; Biological Assay; Cadmium Compounds; Copper; Escherichia coli; Microbial Sensitivity Tests; Nanostructures; Nanotubes, Carbon; Particle Size; Quantum Dots; Reproducibility of Results; Silver; Tellurium; Titanium

We describe the synthesis of an end-functionalized fluorescent dye-labeled poly(N-(2-thiolethyl methacrylamide) as a metal chelating polymer with a very narrow size distribution and controllable molecular weights by reversible addition-fragmentation chain transfer polymerization. In following, we apply this water-soluble metal-chelating polymer for surface modification of cadmium telluride quantum dots (CdTe QDs) by ligand exchange method. The obtained poly(N-(2-thiolethyl methacrylamide)/CdTe QDs hybrid was fully characterized using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TG) and transmission electron microscopy (TEM). The size of the prepared hybrid was estimated around 3.2 nm by TEM. Furthermore, we used this hybrid for improving the release performance of doxorubicin hydrochloride as a chemotherapeutic model drug. The in vitro release of doxorubicin was studied in pH 5.4 and 7.4, which release curves were nicely fitted by the Korsemeyer-Peppas equation and the release followed by non-Fickian diffusion or anomalous diffusion in pH 5.4. The synthesized fluorescent dye-labeled hybrid can be used as a donor-acceptor pair for fluorescence resonance energy transfer (FRET) experiments, so the energy transfer behavior between fluorescent dye as a donor and CdTe QDs as an acceptor were interrogated using Förster/fluorescence resonance energy transfer model, which the distance was found to be 3.95 nm. This present work has potential for both diagnostic and therapeutic aspects for cancer patients.

Topics: Cadmium Compounds; Chelating Agents; Coordination Complexes; Doxorubicin; Energy Transfer; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Hydrogen-Ion Concentration; Particle Size; Polymers; Quantum Dots; Sulfhydryl Compounds; Surface Properties; Tellurium

X-ray image evaluation is commonly performed by determining the detective quantum efficiency (DQE). DQE is calculated with a presampled modulation transfer function (MTF), incident photon fluence, and digital noise power spectrum (NPS). Accurate evaluation of MTF, incident photon fluence, and NPS is important for precise DQE determination. In this study, we focused on the accuracy of the incident photon fluence in mammography. The incident photon fluence is calculated using the squared signal-to-noise ratio (SNR

Topics: Aluminum; Cadmium Compounds; Equipment Design; Mammography; Photons; Reproducibility of Results; Signal-To-Noise Ratio; Spectrum Analysis; Tellurium

The ability to recognize the molecular chirality of enantiomers is extremely important owing to their critical role in drug development and biochemistry. Convenient discrimination of enantiomers has remained a challenge due to lack of unsophisticated methods. In this work, we have reported a simple strategy for chiral recognition of thiol-containing amino acids including penicillamine (PA), and cysteine (Cys). We have successfully designed a nanoparticle-based chemiluminescence (CL) system based on the reaction between cadmium telluride quantum dots (CdTe QDs) and the enantiomers. The different interactions of CdTe QDs with PA enantiomers or Cys enantiomers led to different CL intensities, resulting in the chiral recognition of these enantiomers. The developed method showed the ability for determination of enantiomeric excess of PA and Cys. It has also obtained an enantioselective concentration range from 1.15 to 9.2 mM for PA. To demonstrate the potential application of this method, the designed platform was applied for the quantification of PA in urine and tablet samples. For the first time, we presented a novel practical application of nanoparticle-based CL system for chiral discrimination.

Topics: Cadmium Compounds; Cysteine; Humans; Luminescence; Luminescent Measurements; Nanoparticles; Penicillamine; Quantum Dots; Tablets; Tellurium; Urinalysis

Atherosclerotic plaques constitute the primary cause of heart attack and stroke. However, we still lack a clear identification of the plaques. Here, we evaluate the feasibility of scanning acoustic microscopy (SAM) and time-resolved fluorescence spectroscopy (TRFS) in atherosclerotic plaque characterization. We perform dual-modality microscopic imaging of the human carotid atherosclerotic plaques. We first show that the acoustic impedance values are statistically higher in calcified regions compared with the collagen-rich areas. We then use CdTe/CdS quantum dots for imaging the atherosclerotic plaques by TRFS and show that fluorescence lifetime values of the quantum dots in collagen-rich areas are notably different from the ones in calcified areas. In summary, both modalities are successful in differentiating the calcified regions from the collagen-rich areas within the plaques indicating that these techniques are confirmatory and may be combined to characterize atherosclerotic plaques in the future.

Topics: Aged; Aged, 80 and over; Algorithms; Cadmium Compounds; Carotid Arteries; Equipment Design; Female; Humans; Male; Microscopy, Acoustic; Middle Aged; Plaque, Atherosclerotic; Quantum Dots; Selenium Compounds; Spectrometry, Fluorescence; Tellurium

The determination of detection efficiency and peak-to-total ratios has been performed for rectangular CdTe detectors for various x-ray and low-energy γ-ray source configurations including parallel beams, point, and cylindrical sources. The dependence of efficiency values on axial and off-axial distances, detector thickness and area, and source dimensions has been studied. The detector model developed in this work has been validated by comparing the Monte Carlo simulated values of detector efficiency for a parallel incident beam with the available published data and good agreement has been found with discrepancies remaining within 2% throughout the energy range. Geant4 simulations show nearly 100% photopeak and total efficiency with peak-to-total ratios approaching a maximum value of 1.0 for photons in the 4-70 keV energy range. Similar high values of detection efficiency have been obtained for brachytherapy I-125 seed sources having cylindrical geometries which indicates the suitability of CdTe detectors for the calibration of sources used in therapy. The logistic power curve was found excellent for empirically fitting the photopeak efficiency variations with axial displacement of the I-125 brachy source in the horizontal configuration. Geant4 simulations clearly show that small thicknesses, of the order of 0.5 mm, of CdTe material are sufficient for attaining almost 100% detection efficiency for low-energy photons having energies up to 100 keV.

Topics: Brachytherapy; Cadmium Compounds; Computer Simulation; Radiometry; Stochastic Processes; Tellurium

Clenbuterol (CLB) is harmful to human health when used long term, and it has been listed by the World Anti-Doping Agency (WADA). In this work, a novel zinc-based metal-organic frameworks-reduced graphene oxide-CdTe quantum dots (ZnMOF-RGO-CdTe QDs) hybrid was used to construct an electrochemiluminescence (ECL) sensor for detecting CLB. CdTe QDs, loaded by RGO, exhibited an enhanced ECL signal. In addition, the ZnMOFs catalyzed OH

Topics: Biosensing Techniques; Cadmium Compounds; Clenbuterol; Drug Stability; Graphite; Limit of Detection; Luminescence; Metal-Organic Frameworks; Quantum Dots; Reproducibility of Results; Signal Detection, Psychological; Tellurium; Zinc

Sulfadiazine is an environmental pollutant derived from abuse of antibiotics. Its content in environmental water is closely related to human health. Thus, a novel dual-emission surface molecularly imprinted nanosensor is designed for the specific adsorption and detection of sulfadiazine. In the system, blue emissive carbon quantum dots wrapped with silica served as the internal reference signal for eliminating background interference, while red emissive thioglycolic acid modified CdTe quantum dots (CdTe QDs), which are low dimensional semiconductor materials by the combination of cadmium and tellurium with excellent optical properties, were encapsulated in the imprinted layer to offer recognition signal. The fluorescence of CdTe quantum dots was quenched and the fluorescence quenching degree of carbon quantum dots was inconspicuous with the increase of concentration of sulfadiazine, thereby reflecting the color change. The detection of sulfadiazine was successfully achieved in a concentration range of 0.25-20 μmol/L with detection limit of 0.042 μmol/L and nanosensors had specific recognition for sulfadiazine over its analogues. Compared to single-emission fluorescence sensors, ratiometric fluorescence nanosensors had wider linear range and higher detection accuracy. Furthermore, the nanosensors were also successfully applied for the determination of sulfadiazine in real water and milk samples with acceptable recoveries. The study provides a feasible method for the detection of sulfadiazine and a reference for the detection of sulfonamides.

Topics: Cadmium Compounds; Carbon; Fluorescence; Fluorescent Dyes; Molecular Imprinting; Molecular Structure; Particle Size; Polymers; Quantum Dots; Spectrometry, Fluorescence; Sulfadiazine; Surface Properties; Tellurium

Ions greatly influence protein structure-function and are critical to health and disease. A 10, 000-fold higher calcium in the sarcoplasmic reticulum (SR) of muscle suggests elevated calcium levels near active calcium channels at the SR membrane and the impact of localized high calcium on the structure-function of the motor protein myosin. In the current study, combined quantum dot (QD)-based nanothermometry and circular dichroism (CD) spectroscopy enabled detection of previously unknown enthalpy changes and associated structural remodeling of myosin, impacting its function following exposure to elevated calcium. Cadmium telluride QDs adhere to myosin, function as thermal sensors, and reveal that exposure of myosin to calcium is exothermic, resulting in lowering of enthalpy, a decrease in alpha helical content measured using CD spectroscopy, and the consequent increase in motor efficiency. Isolated muscle fibers subjected to elevated levels of calcium further demonstrate fiber lengthening and decreased motility of actin filaments on myosin-functionalized substrates. Our results, in addition to providing new insights into our understanding of muscle structure-function, establish a novel approach to understand the enthalpy of protein-ion interactions and the accompanying structural changes that may occur within the protein molecule.

Topics: Animals; Cadmium Compounds; Calcium; Circular Dichroism; Mice; Myosins; Protein Structure, Quaternary; Quantum Dots; Structure-Activity Relationship; Tellurium; Thermometry

CdTe quantum dots (QDs) were integrated with polyethyleneimine-coated carbon dots (PEI-CDs) to form a dually emitting probe for heparin. The red fluorescence of the CdTe QDs is quenched by the PEI-CDs due to electrostatic interactions. In the presence of heparin, the blue fluorescence of PEI-CDs remains unaffected, while its quenching effect on the fluorescence of CdTe QDs is strongly reduced. A ratiometric fluorometric assay was worked out. The ratio of the fluorescences at 595 and 436 nm serves as the analytical signal. Response is linear in the concentration range of 50-600 ng·mL

Topics: Cadmium Compounds; Carbon; Fluorometry; Heparin; Humans; Hydrogen-Ion Concentration; Polyethyleneimine; Quantum Dots; Tellurium; Time Factors

Herein, an ultrasensitive photoelectrochemical (PEC) assay was developed for the monitoring of microRNA-141 (miRNA-141) based on poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2- b:4,5- b']dithiophene-2,6-diyl- alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophene-4,6-diyl}/CdTe quantum dots ( PTB7-Th/CdTe QDs) sensitized structure as signal tag and the benzo-4-chlorohexadienone (4-CD) precipitate as efficient quencher. PTB7-Th and CdTe QDs were successively modified on the electrode surface to form a novel sensitized structure with eminent photovoltaic performances and surpassing film-forming ability. The PTB7-Th/CdTe QDs sensitized structure served as signal tag for achieving a strong initial PEC signal. Besides, a tiny amount of target (miRNA-141) could be transformed into numerous DNA products via enzyme-assisted target cycling procedure, which further triggered the formation of a DNA supersandwich structure on the electrode surface for loading abundant manganese porphyrin (MnPP). Thereafter, MnPP as mimetic enzyme could catalyze 4-chloro-1-naphthol (4-CN) to generate 4-CD precipitate on the sensing interface in the presence of H

Topics: Biosensing Techniques; Cadmium Compounds; Catalysis; Electrochemical Techniques; Humans; Hydrogen Peroxide; Limit of Detection; MicroRNAs; Naphthols; Quantum Dots; Tellurium; Thiophenes

The unique features of quantum dots (QDs) make them desirable fluorescent tags for cell and developmental biology applications that require long-term, multitarget, and highly sensitive imaging. In this work, we imaged fluorescent cadmium telluride/zinc sulfide (CdTe/ZnS) QDs in organs, tissues, and cells, and analyzed the mechanism of their lymphatic uptake and cellular distribution. We observed that the fluorescent CdTe/ZnS QDs were internalized by lymph nodes in four cell lines from different tissue sources. We obtained the fluorescence intensity-QD concentrations curve by quantitative analysis. Our results demonstrate that cells containing QDs can complete mitosis normally and that distribution of QDs was uniform across cell types and involved the vesicular transport system, including the endoplasmic reticulum. This capacity for CdTe/ZnS QD targeting provides insights into the applicability and limitations of fluorescent QDs for imaging biological specimens.

Topics: Animals; Cadmium Compounds; Diagnostic Imaging; Endoplasmic Reticulum; Female; Human Umbilical Vein Endothelial Cells; Intracellular Space; Lymph Nodes; Mice; Mice, Inbred BALB C; Micelles; Mitosis; Quantum Dots; RAW 264.7 Cells; Spectrometry, Fluorescence; Sulfides; Tellurium; Tissue Distribution; Zinc Compounds

Fluorescent "turn-off" sensors based on water-soluble quantum dots (QDs) have drawn increasing attention owing to their unique properties such as high fluorescence quantum yields, chemical stability and low toxicity. In this work, a novel method based on the fluorescence "turn-off" model with water-soluble CdTe QDs as the fluorescent probes for differentiation of 29 different famous green teas is established. The fluorescence of the QDs can be quenched in different degrees in light of positions and intensities of the fluorescent peaks for the green teas. Subsequently, with aid of classic partial least square discriminant analysis (PLSDA), all the green teas can be discriminated with high sensitivity, specificity and a satisfactory recognition rate of 100% for training set and 98.3% for prediction set, respectively. Especially, the "turn-off" fluorescence PLSDA model based on second-order derivatives (2nd der) with reduced least complexity (LVs = 3) was the most effective one for modeling. Most importantly, we further demonstrated the established "turn-off" fluorescent sensor mode has several significant advantages and appealing properties over the conventional fluorescent method for large-class-number classification (LCNC) of green teas. This work is, to the best of our knowledge, the first report on the rapid and effective identification of so many kinds of famous green teas based on the "turn-off" model of QDs combined with chemometrics, which also implies other potential applications on complex LCNC classification system with weak fluorescence or even without fluorescence to achieve higher detective response and specificity.

Topics: Cadmium Compounds; Chemistry Techniques, Analytical; Fluorescent Dyes; Informatics; Limit of Detection; Quantum Dots; Solubility; Spectrometry, Fluorescence; Tea; Tellurium; Time Factors; Water

The effect of 3-mercaptopropionic acid (MPA)-capped CdTe quantum dots (QDs) on lysozyme was systematically investigated by spectroscopic methods, enzyme activity assay, and calorimetry techniques. Results show that the MPA-capped CdTe QDs binded to lysozyme through van der Walls forces and hydrogen bondings, causing the decrement of α-helical content (∼7%) and increment of β-sheet content (∼11%) of lysozyme. The binding caused static quenching of the fluorescence, while the microenvironment of aromatic amino acid residues did not show any significant alteration. The lysozyme activity was affected by the increasing exposure of QDs, it was inhibited to 53.77% under a 6 × 10

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Calorimetry, Differential Scanning; Chickens; Fluorescence; Hydrogen Bonding; Muramidase; Protein Structure, Secondary; Quantum Dots; Structure-Activity Relationship; Tellurium

The next step in the boron neutron capture therapy (BNCT) is the real time imaging of the boron concentration in healthy and tumor tissue. Monte Carlo simulations are employed to predict the detector response required to realize single-photon emission computed tomography in BNCT, but have failed to correctly resemble measured data for cadmium telluride detectors. In this study we have tested the gamma production cross-section data tables of commonly used libraries in the Monte Carlo code MCNP in comparison to measurements. The cross section data table TENDL-2008-ACE is reproducing measured data best, whilst the commonly used ENDL92 and other studied libraries do not include correct tables for the gamma production from the cadmium neutron capture reaction that is occurring inside the detector. Furthermore, we have discussed the size of the annihilation peaks of spectra obtained by cadmium telluride and germanium detectors.

Topics: Boron; Boron Neutron Capture Therapy; Cadmium Compounds; Computer Simulation; Humans; Isotopes; Monte Carlo Method; Neoplasms; Phantoms, Imaging; Radiometry; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Spectrometry, Gamma; Tellurium; Tomography, Emission-Computed, Single-Photon

A sensitive fluorescence sensor for the detection of malachite green (MG) was fabricated by grafting molecularly imprinted polymers (MIPs) onto the surface of CdTe quantum dots (QDs). The MIP-coated QDs were synthesized via a reverse microemulsion method using (3-aminopropyl)triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) as functional monomer and cross-linker, respectively. The optimum molar ratio of MG, functional monomer and cross-linker was 1:3:10. The MIP-coated QDs exhibited uniform spheres with diameter around 49nm and excellent fluorescence emission at λ

Topics: Animals; Cadmium Compounds; Fishes; Food Contamination; Limit of Detection; Molecular Imprinting; Quantum Dots; Rosaniline Dyes; Silicon Dioxide; Tellurium

Quantum dots (QDs) are fluorescent nanocrystals that present unique optical properties, especially a high photostability. However, their use for intracellular studies is still limited since their passage through the living cell membranes does not occur passively. In this work, we adapted the ethanol injection method to encapsulate cationic hydrophilic QDs into fusogenic liposomes, to deliver them in living cells. Liposomes were characterized using zeta potential, dynamic light scattering (DLS), fluorescence microscopy and transmission electron microscopy (TEM). Red blood cells (RBCs) were applied as models in this study to probe the liposome fusion with the cell membrane since RBCs do not present endocytic activity. Therefore, HeLa cells were also applied to test the QDs delivery by the liposomes. The TEM and the fluorescence microscopy confirmed the QDs encapsulation, with an efficiency of 43%, determined by UV-vis spectroscopy. Zeta potential showed that the QDs-loaded fusogenic liposomes were positively charged and presented an average size of 343nm, determined by DLS. Furthermore, fluorescence microscopy analyses of RBCs and HeLa cells confirmed the liposomes fusion with the cell membrane and suggested the release of QDs into cells. Thus, we expect that this work will contribute to improve the use of QDs as fluorescent probes to intracellular studies.

Topics: Cadmium Compounds; Cations; Cysteamine; Dynamic Light Scattering; Erythrocytes; HeLa Cells; Humans; Liposomes; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Quantum Dots; Tellurium

A facile one-pot method was proposed to synthesis cysteamine capped CdTe QDs with a high quantum yield 30%. In the synthesis process, nitrogen protection, ultrasonic treatment, and light irradiation were unnecessary. Additionally, potassium tellurite was used instead of Te powder as Te source, avoiding of the time-consuming Te powder dissolution process. The prepared QDs were found to be Hg

Topics: Biosensing Techniques; Cadmium Compounds; Color; Cysteamine; Fluorescence; Limit of Detection; Mercury; Quantum Dots; Tellurium; Water

3-Mercaptopropionic Acid-modified CdTe quantum dots (QDs) were synthesized and characterized by infrared, fluorescence, and ultraviolet-visible absorption spectra and Nano-ZetaSizer measurements. Then the interaction between QDs and hemoglobin was studied to investigate the effects of QDs on the structure and function of hemoglobin by using a variety of spectroscopy methods and isothermal titration calorimetry. The results showed van der Waals forces and hydrogen bonding predominantly played major roles in the binding. The intrinsic fluorescence of hemoglobin was quenched with changes to the microenvironment of tyrosine and tryptophan residues and complex conformational changes of hemoglobin were induced with the loosening and unfolding skeleton. However, the heme in hemoglobin was still stable, indicating that the main physiological function of hemoglobin might not be significantly inhibited. This study will provide a new strategy to study the biological toxicity of QDs at the molecular level.

Topics: Animals; Cadmium Compounds; Cattle; Hemoglobins; Quantum Dots; Spectrum Analysis; Tellurium

Listeria monocytogenes is a recognized foodborne pathogen that causes listeriosis in susceptible consumers. Currently, the detection systems for Listeria in food detect live and dead bacteria, being the viable microorganisms most relevant for their ability to cause sickness in the population at risk. For this reason, a new nanohybrid compound was developed for the optical detection of Listeria that was based on polyamidoamine dendrimers functionalized with an auxotrophic cofactor (lipoic acid), together with the coupling of fluorescent semiconductor crystals (quantum dots). The nanohybrid sensor has a detection limit for viable L. monocytogenes of 5.19 × 10

Topics: Anti-Bacterial Agents; Biological Assay; Cadmium Compounds; Food Contamination; Food Microbiology; Listeria monocytogenes; Quantum Dots; Tellurium

Cytochrome c (Cyt c) is commonly used as intrinsic biomarker for several characteristics of the cell such as respiration, energy level and apoptosis. In the present study a simple colorimetric sensor should be developed and tested for the real-time detection of Cyt c in living cells. We synthesized cadmium telluride quantum dots (CdTe QDs) capped with thioglycolic acid (TGA) as a fluorometric Cyt c nanosensor. The synthesized TGA/CdTe QDs nanosensor was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and absorption as well as fluorescence spectrophotometry. We investigated the developed TGA/CdTe QDs sensor with regard to its applicability in the fluorometric detection of Cyt c. Results showed that the TGA/CdTe QDs could be used as a sensitive fluorescence probe for the quantification of different concentrations of Cyt c ranging from 0.5 - 2.5μM. Increased binding of QDs to Cyt c results in decreasing fluorescence. The fluorescence of the QDs is inversely correlated to the Cyt c concentration. Based on these data, a standard curve up to 2.5μM Cyt c was established. Moreover, the developed nanosensor was applied in different concentrations on primary human dermal fibroblasts. Results showed that TGA/CdTe QDs were taken up by cells and could be visualized by fluorescence microscopy. Quantification of Cyt c within living cells via QDs is, however, influenced by various factors such as cell damage, QD aggregation or the level of reactive oxygen species, which have to be taken into account.

Topics: Biosensing Techniques; Cadmium Compounds; Cytochromes c; Fluorescent Dyes; Humans; Microscopy, Electron, Transmission; Quantum Dots; Spectrometry, Fluorescence; Tellurium

The concentration of L-cysteine (Cys) and glutathione (GSH) is closely related to the critical risk of various diseases. In our study, a new rapid method for the determination of Cys and GSH in water and urine samples has been developed using a fluorescent probe technique, which was based on crystal violet (CV)-functionalized CdTe quantum dots (QDs). The original QDs emitted fluorescence light, which was turned off upon adding CV. This conjugation of CV and QDs could be attributed to electrostatic interaction between COO

Topics: Cadmium Compounds; Cysteine; Fluorescent Dyes; Gentian Violet; Glutathione; Humans; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

Topics: Animals; Antibiotics, Antineoplastic; Cadmium Compounds; Delayed-Action Preparations; Doxorubicin; Gadolinium; HeLa Cells; Humans; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Mice; Nanocomposites; Neoplasms; Optical Imaging; Permeability; Quantum Dots; Tellurium; Theranostic Nanomedicine; Yolk Sac

A novel sensitive method for detection of DNA methylation was developed with thioglycollic acid (TGA)-capped CdTe quantum dots (QDs) as fluorescence probes. Recognition of methylated DNA sites would be useful strategy due to the important roles of methylation in disease occurrence and developmental processes. DNA methylation occurs most often at cytosine-guanine sites (CpG dinucleotides) of gene promoters. The QDs significantly interacted with hybridized unmethylated and methylated DNA. The interaction of CpG rich methylated and unmethylated DNA hybrid with quantum dots as an optical probe has been investigated by fluorescence spectroscopy and electrophoresis assay. The fluorescence intensity of QDs was highly dependent to unmethylated and methylated DNA. Specific site of CpG islands of Adenomatous polyposis coli (APC), a well-studied tumor suppressor gene, was used as the detection target. Under optimum conditions, upon the addition of unmethylated dsDNA, the fluorescence intensity increased in linear range from 1.0 × 10

Topics: Adenomatous Polyposis Coli Protein; Cadmium Compounds; CpG Islands; DNA; Fluorescence; Fluorescent Dyes; Humans; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium

The increasing use of nanoparticles in consumer products raises the concerns of their safety. This study investigated the biological effects of quantum dots (QD) exposure to rats during pregnancy. CdTe QD were injected on the 13th gestation day. Morphological features of 121 fetuses and histological analysis of placentas were performed on the 20th gestation day. The results showed that QD exhibit dose dependent embryotoxicity: survival rates of fetuses were 97% (5mg/kg dose), 86% (10mg/kg dose) and 43% (20mg/kg dose). QD exposure also resulted in the reduction of fetal body length and mass, disturbed ossification of limbs and caused placental tissue damage. QD exhibit no teratogenic effects at the applied doses. It is hypothesized that embryogenesis was impeded due to the placental damage rather than QD penetration and accumulation in the fetuses. To conclude, mothers should be protected from QD exposure during pregnancy.

Topics: Animals; Cadmium Compounds; Embryo, Mammalian; Embryonic Development; Female; Fetus; Maternal-Fetal Exchange; Placenta; Pregnancy; Quantum Dots; Rats, Wistar; Tellurium

Each imaging modality has its own merits and intrinsic limitations; therefore, combining two or more complementary imaging modalities has become an interesting area of research. Recently, magnetic ion-doped quantum dots have become an increasingly promising class of optical/magnetic resonance multimodal imaging probes due to their excellent physical and chemical properties. In this work, Gd-doped CdTe quantum dots (QDs) were successfully synthesized via a facile one-step refluxing route,and their optimal synthesis conditions were investigated. The prepared CdTe:Gd QDs were shown to exhibit good optical properties with high quantum yields up to 69%, high longitudinal relaxivity (r

Topics: Animals; Axons; Cadmium Compounds; Chemistry Techniques, Synthetic; Gadolinium; Hydrogen-Ion Concentration; Magnetic Resonance Imaging; Mice; Multimodal Imaging; NIH 3T3 Cells; Optical Imaging; Quantum Dots; Tellurium

The effect of N-acetyl-l-cysteine-capped CdTe quantum dots (NAC-CdTe QDs) with different sizes on lysozyme was investigated by isothermal titration calorimetry (ITC), enzyme activity assays, and multi-spectroscopic methods. ITC results proved that NAC-CdTe QDs can spontaneously bind with lysozyme and hydrophobic force plays a major role in stabilizing QDs-lysozyme complex. Multi-spectroscopic measurements revealed that NAC-CdTe QDs caused strong quenching of the lysozyme's fluorescence in a size-dependent quenching manner. Moreover, the changes of secondary structure and microenvironment in lysozyme caused by the NAC-CdTe QDs were higher with a bigger size. The results of enzyme activity assays showed that the interaction between lysozyme and NAC-CdTe QDs inhibited the activity of lysozyme and the inhibiting effect was in a size-dependent manner. Based on these results, we conclude that NAC-CdTe QDs with larger particle size had a larger impact on the structure and function of lysozyme.

Topics: Acetylcysteine; Cadmium Compounds; Catalytic Domain; Enzyme Inhibitors; Muramidase; Particle Size; Protein Binding; Protein Structure, Secondary; Quantum Dots; Tellurium; Thermodynamics

Although quantum dot (QD)-induced toxicity occurs due to free radicals, generation of oxidative stress mediated by reactive oxygen species (ROS) formation is considered an important mechanism. However, free radical mechanisms are essentially difficult to elucidate at the molecular level because most biologically relevant free radicals are highly reactive and short-lived, making them difficult to directly detect, especially in vivo. Antioxidants play an important role in preventing or, in most cases, limiting the damage caused by ROS. Healthy people and animals possess many endogenous antioxidative substances that scavenge free radicals in vivo to maintain the redox balance and genome integrity. The antioxidant capacity of an organism is highly important but seldom studied. In this study, the dose and time effects of CdTe QDs on the antioxidant capacities of the liver and kidneys were investigated in mice using the electron paramagnetic resonance (EPR) spin-trapping technique. We found that the liver and kidneys of healthy mice contain specific antioxidant capacities that scavenge ·OH and ·O

Topics: Animals; Antioxidants; Cadmium Compounds; Catalase; Dose-Response Relationship, Drug; Electron Spin Resonance Spectroscopy; Free Radicals; Glutathione; Glutathione Peroxidase; Kidney; Liver; Male; Malondialdehyde; Mice; Oxidative Stress; Quantum Dots; Superoxide Dismutase; Tellurium

Photoelectrochemical (PEC) biosensors are usually based on the single photocurrent change caused by biorecognition events between analytes and probes. However, the photocurrent may be influenced by other factors besides target analytes and bring a false result. To improve the accuracy and reliability of PEC detection, here we proposed the design of a dual channel self-reference PEC biosensors. CdTe and CdTe-graphene oxide (GO) were chosen as the two PEC active material and modified onto two adjacent areas on the ITO electrode. Then they were functionalized with Aflatoxin B1 (AFB1) aptamer through covalent binding or physical adsorption, respectively. The cathodic current from CdTe-GO and anodic current from CdTe can be well distinguished by adjusting the bias voltage. With the simultaneous application of "signal on" and "signal off" model, dual concentration information may be obtained in one detection and serve as a reference for each other. By comparing these two results, this sensor can clearly distinguish whether the signal change was caused by AFB1 or other interference factors. Compared to traditional PEC biosensors, this design can provide a better accuracy and reliability, which is promising in the future development of PEC detection.

Topics: Aflatoxin B1; Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Electrodes; Equipment Design; Graphite; Nanocomposites; Tellurium; Tin Compounds

In this work, as a novel fluorescent nano-sensor, a ligand-capped CdTe QDs (CdTe-L QDs) was designed for the detection and quantification of Cu

Topics: Biosensing Techniques; Cadmium Compounds; Copper; Environmental Monitoring; Fluorescence; Fluorescent Dyes; Ligands; Limit of Detection; Nanotechnology; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water Pollutants, Chemical

Thanks to quantum dots' (QDs) properties, they can be used as selective and sensitive biomarkers in molecular imaging. In a previous paper, we confirmed the possibility of interaction between mercaptosuccinic acid-capped cadmium telluride QDs (MSA-CdTe) and human metallothionein (MT). The aim of this study was to expand on our previous research with an evaluation of the stability of the formed complexes between human MT and four CdTe compounds of the following sizes: 3.4nm (blue QDs), 3.8nm (green QDs), 4.5nm (yellow QDs), and 5.2nm (red QDs). Complexes were evaluated over time using fluorescence intensity and differential pulse voltammetry. Differences between the voltammograms obtained for standard solutions and for CdTe+MT show that complexes were formed. An increase in fluorescence intensity was observed for blue (Δ%≈40 for t=1→120min) and red (Δ%≈30 for t=1→120min) CdTe-MT complexes than CdTe alone, whereas green and yellow CdTe-MT complexes had a lower fluorescence intensity than CdTe alone. A stronger time dependence of the mercaptosuccinic acid (MSA) peak height on the timeline and differences in the MSA peak shape (in CdTe, and CdTe+MT complexes) were also observed by voltammetry. Authors noticed a decrease in the Cat2 signal of the red and green CdTe+MT complexes at the time of conjugation. Our results reveal that the size of QDs has an impact on the interaction between CdTe and human MT, as well as on the stability of complexes formed during these interactions. The bioconjugates' stability was also found to depend on the time of interaction.

Topics: Cadmium Compounds; Electrochemical Techniques; Fluorescence; Humans; Kinetics; Metallothionein; Protein Binding; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Time Factors

Topics: alpha-Fetoproteins; Antibodies; Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; Color; Electrochemical Techniques; Immunoassay; Limit of Detection; Luminescent Measurements; Nanoparticles; Sulfides; Tellurium

Nanocomposites are materials with unique properties and a wide range of applications. The combination of different nanostructures with traditional materials gives a variety of possibilities that should be analyzed. Especially, functional fluorescent semiconductor quantum dots (QDs) embedded in polymeric matrices have shown promising fluorescence and biocompatibility properties. These hybrid materials can be used in medical applications such as biodiagnostic and bioimaging. In this study, two hydrogels, one of polyethylene glycol diacrylate (PEGDA) and other of polyacrylamide (PAAm), were prepared with quantum dots of CdTe (4 nm of diameter) and characterized. The aim of this research was to analyze the optical properties of the nanocomposites and their cell viability. QDs nanocomposites were fabricated by a free radical polymerization process. The optical studies showed that the nanocomposites have well defined properties of fluorescence. To study the biocompatibility of the nanocomposites, metastatic B16f10 cell line were used and MTT assay was performed. The nanocomposites had a significant improved cell viability compared with QDs solutions.

Topics: Acrylic Resins; Animals; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Fluorescent Dyes; Hydrogel, Polyethylene Glycol Dimethacrylate; Mice; Nanocomposites; Particle Size; Quantum Dots; Tellurium

Flavonoids are polyphenols that help the maintenance of health, aiding the prevention of diseases. In this work, CdTe QDs coated with 3-mercaptopropionic acid (3MPA), with an average size of 2.7nm, were used as photoluminescence probe for flavonoids in different conditions. The interaction between 14 flavonoids and QDs was evaluated in aqueous dispersions in the absence and in the presence of cetyltrimethylammonium bromide (CTAB). To establish a relationship between photoluminescence quenching and the concentration of flavonoids, the Stern-Volmer model was used. In the absence of CTAB, the linear ranges for quercetin, morin and rutin were from 5.0×10

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Cetrimonium; Cetrimonium Compounds; Flavonoids; Luminescence; Micelles; Particle Size; Pyrenes; Quantum Dots; Solutions; Surface-Active Agents; Tellurium; Water

Lysozyme with a small monomeric globular enzymatic protein is part of the innate immune system, and its deficiency can cause the increased incidence of disease. Herein, we devise a new signal-enhanced fluorescence aptasensing platform for quantitative screening of lysozyme by coupling with rolling circle amplification (RCA) and strand hybridization reaction, accompanying the assembly of CdTe/CdSe quantum dots (QDs) and hemin/G-quadruplex DNzyme. Initially, target-triggered release of the primer was carried out from DNA duplex via the reaction of the aptamer with the analyte, and the released primer could be then utilized as the template to produce numerous repeated oligonucleotide sequences by the RCA reaction. Following that, the formed long-stranded DNA simultaneously hybridized with the CdTe/CdSe QD-labeled probe and hemin/G-quadruplex DNzyme strand in the system, thereby resulting in the quenching of QD fluorescent signal through the proximity hemin/G-quadruplex DNzyme on the basis of transferring photoexcited conduction band electrons of quantum dots to Fe(III)/Fe(II)-protoporphyrin IX (hemin) complex. Under optimal conditions, the fluorescent signal decreased with the increasing target lysozyme within the dynamic range from 5.0 to 500nM with a detection limit (LOD) of 2.6nM at the 3s

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; DNA, Catalytic; Fluorescent Dyes; G-Quadruplexes; Hemin; Humans; Limit of Detection; Muramidase; Nucleic Acid Amplification Techniques; Quantum Dots; Selenium Compounds; Spectrometry, Fluorescence; Tellurium

In this work, we report the synthesis, characterization and biological application of highly stable CdTe/ZnS (cadmium tellurite/zinc sulphide) Core/Shell (CS) quantum dots (QDs) capped with mercaptosuccinic acid (MSA). The CS QDs were synthesized using a simple one-pot aqueous method. The synthesized CdTe/ZnS CS QDs were found to exhibit excellent stability even 100 days after preparation and also showed better photoluminescence quantum yield (PLQY) of about 50% compared with that of only CdTe QDs which was nearly 12%. The formation of the CdTe/ZnS CS was confirmed by high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infra-red (FTIR) and X-ray diffraction (XRD) analyses. Further, on extending our study towards bioimaging of E. coli cells using the QDs samples, we found that CdTe/ZnS CS QDs showed better results compared with CdTe QDs.

Topics: Cadmium Compounds; Cells, Cultured; Escherichia coli; Luminescent Measurements; Quantum Dots; Sulfides; Tellurium; Water; Zinc Compounds

Mycobacterium tuberculosis is a serious global infectious pathogen causing tuberculosis (TB). The development of an easy and sensitive method for the detection of M. tuberculosis is in urgent need due to complex and low specificity of the current assays. Herein, we present a novel method for M. tuberculosis detection based on a sandwich assay via antigen-antibody interaction using silica-coated quantum dots (SiQDs) and gold nanorods (AuNRs). A genetically engineered recombinant antibody (GBP-50B14 and SiBP-8B3) was bound to surfaces of AuNRs and SiQDs respectively, without any surface modification. The antigen-antibody interaction was revealed using M. tuberculosis-specific secretory antigen, Ag85B. Two biocomplexes showed a quenching effect in the presence of the target antigen through a sandwich assay. The assay response was in the range of 1×10

Topics: Acyltransferases; Antigens, Bacterial; Bacterial Proteins; Cadmium Compounds; Gold; Humans; Immunoassay; Immunoconjugates; Limit of Detection; Mycobacterium tuberculosis; Nanotubes; Quantum Dots; Surface Plasmon Resonance; Tellurium; Tuberculosis

Topics: Biosensing Techniques; Cadmium Compounds; Enzyme Assays; Fluorescent Dyes; Glucose Oxidase; Limit of Detection; Nanocomposites; Organometallic Compounds; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Urate Oxidase

Arginine plays an important role in many biological functions, whose detection is very significant. Herein, a sensitive, simple and cost-effective fluorescent method for the detection of arginine has been developed based on the inner filter effect (IFE) of citrate-stabilized gold nanoparticles (AuNPs) on the fluorescence of thioglycolic acid-capped CdTe quantum dots (QDs). When citrate-stabilized AuNPs were mixed with thioglycolic acid-capped CdTe QDs, the fluorescence of CdTe QDs was significantly quenched by AuNPs via the IFE. With the presence of arginine, arginine could induce the aggregation and corresponding absorption spectra change of AuNPs, which then IFE-decreased fluorescence could gradually recover with increasing amounts of arginine, achieving fluorescence "turn on" sensing for arginine. The detection mechanism is clearly illustrated and various experimental conditions were also optimized. Under the optimum conditions, a decent linear relationship was obtained in the range from 16 to 121μgL

Topics: Arginine; Biosensing Techniques; Cadmium Compounds; Fluorescence; Gold; Humans; Hydrogen Bonding; Hydrogen-Ion Concentration; Limit of Detection; Metal Nanoparticles; Microscopy, Electron, Transmission; Quantum Dots; Sensitivity and Specificity; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates

In this paper, a systematic investigation of the interaction of bovine serum albumin (BSA) with water-soluble CdTe quantum dots (QDs) of two different sizes capped with carboxylic thiols is presented based on steady-state and time-resolved fluorescence measurements. Efficient Förster resonance energy transfer (FRET) was observed to occur from BSA donor to CdTe acceptor as noted from reduction in the fluorescence of BSA and enhanced fluorescence from CdTe QDs. FRET parameters such as Förster distance, spectral overlap integral, FRET rate constant and efficiency were determined. The quenching of BSA fluorescence in aqueous solution observed in the presence of CdTe QDs infers that fluorescence resonance energy transfer is primarily responsible for the quenching phenomenon. Bimolecular quenching constant (k

Topics: Cadmium Compounds; Fluorescence; Fluorescence Resonance Energy Transfer; Quantum Dots; Serum Albumin, Bovine; Spectrophotometry, Ultraviolet; Tellurium; Thermodynamics

Currently there is an urgent need for multi-mycotoxin detection methods due to the co-occurrence of multiple mycotoxins in food raw materials and their augmented toxicity. Herein, a magneto-controlled aptasensor has been developed for simultaneous electrochemical detection of ochratoxin A (OTA) and fumonisin B1 (FB1), two typical mycotoxins found in food crops world-wide. This aptasensor was designed using the high specificity between the target and aptamer with heavy CdTe or PbS quantum dots (QDs) coated silica as labels and the complementary DNA functionalized magnetic beads as capture probes. In presence of targets, the aptamer preferred to form the target-aptamer binding which forced the partial release of the preloaded labels from the magnetic beads. After a one-step incubation and a simple magnetic separation, the electrochemical signals of Cd

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Food Analysis; Food Contamination; Fumonisins; Lead; Limit of Detection; Magnetics; Magnets; Ochratoxins; Quantum Dots; Silicon Dioxide; Sulfides; Tellurium; Zea mays

The present study reports the fabrication of mesoporous-structured ratiometric molecularly imprinted sensors using a combined surface-imprinted and ratiometric fluorescence method. The sensors were subsequently examined in the selective and sensitive determination of 2,4,6-trinitrophenol (TNP). In the preparation of the ratiometric system, the reference dye CdTe quantum dots were embedded in silica core particles via the Stöber method; the functional target sensitive dye AAMBT&SiO

Topics: Biosensing Techniques; Cadmium Compounds; Hydroxybenzoate Ethers; Molecular Imprinting; Nanoparticles; Picrates; Polymers; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium; Water Pollutants, Chemical

Different kinds of panels (Si-based panels and CdTe panels) were treated according to a common process route made up of two main steps: a physical treatment (triple crushing and thermal treatment) and a chemical treatment. After triple crushing three fractions were obtained: an intermediate fraction (0.4-1mm) of directly recoverable glass (17%

Topics: Aluminum; Cadmium Compounds; Chemical Fractionation; Copper; Environmental Monitoring; Iron; Metals, Heavy; Recycling; Silicon; Silver; Tellurium; Zinc

Plastic and reconstructive surgeons increasingly apply adipose tissue grafting in a clinical setting, although the anticipation of graft survival is insecure. There are only few tools for tracking transplanted fat grafts in vivo.Murine adipose tissue clusters were incubated with negatively charged, mercaptoproprionic acid-coated cadmium telluride quantum dots (QDs) emitting in the dark red or near infrared. The intracellular localization of QDs was studied by confocal laser scanning microscopy.As a result, the adipose tissue clusters showed a proportional increase in fluorescence with increasing concentrations (1, 10, 16, 30, 50 nM) of cadmium telluride QDs. Laser scanning microscopy demonstrated a membrane bound localization of QDs. Vacuoles and cell nuclei of adipocytes were spared by QDs. We conclude that QDs were for the first time proven intracellular in adult adipocytes and demonstrate a strong fluorescence signal. Therefore, they may play an essential role for in vivo tracking of fat grafts.

Topics: Animals; Cadmium Compounds; Luminescent Agents; Mice; Mice, Inbred BALB C; Microscopy, Confocal; Quantum Dots; Spectroscopy, Near-Infrared; Subcutaneous Fat; Tellurium

The assembly of quantum dots (QDs) in a simply method opens up opportunities to obtain access to the full potential of assembled QDs by virtue of the collective properties of the ensembles. In this study, quantum dots CdTe and graphene (Gr) nanocomposite was constructed for the simultaneous determination of uric acid (UA) and dopamine (DA). The CdTe QDs-Gr nanocomposite was prepared by ultrasonication and was characterized with microscopic techniques. The nanocomposite modified electrode was characterized by cyclicvoltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effects between CdTe QDs and Gr, the fabricated electrode exhibited excellent electrochemical catalytic activities, good biological compatibility and high sensitivity toward the oxidation of UA and DA. Under optimum conditions, in the co-existence system the linear calibration plots for UA and DA were obtained over the range of 3-600 μM and 1-500 μM with detection limits of 1.0 μM and 0.33 μM. The fabricated biosensor also exhibits the excellent repeatability, reproducibility, storage stability along with acceptable selectivity.

Topics: Biosensing Techniques; Cadmium Compounds; Dielectric Spectroscopy; Dopamine; Electrodes; Graphite; Humans; Limit of Detection; Nanocomposites; Oxidation-Reduction; Quantum Dots; Reproducibility of Results; Tellurium; Uric Acid

Red-light-emitting water-soluble semiconducting quantum dots (QDs) were synthesized by using a wide variety of commercially available thiol-type capping agents. QDs with a negatively charged nanosurface showed excellent selectivity for paraquat (PQ) at pH 7.4 over other commonly encountered pesticides/herbicides, including diquat (DQ). The presence of a 4,4'-bis-pyridinium unit in PQ enabled it to initiate long-range aggregation, thereby leading to the formation of nanostructures with excellent emission-quenching behavior. Precoated quartz plates were developed as a low-cost, portable sensor for the on-site detection of PQ in both natural water and human urine. Estimation of the PQ concentration was performed in different commercial formulations and the detection of PQ contamination in adulterated dairy product was also achieved with excellent sensitivity. Finally, we screened more than 50 different food items, including vegetables, fruits, cereals, and fodders, to construct a generalized marker for any residual PQ in such specimens.

Topics: Cadmium Compounds; Crops, Agricultural; Food Analysis; Food Contamination; Herbicides; Light; Nanoparticles; Particle Size; Surface Properties; Tellurium

Thorough characterization of toxic effects of nanoparticles (NP) is desirable due to the increasing risk of potential environmental contamination by NP. In the current study, we combined three recently developed proteomics approaches to assess the effects of Au, CuO, and CdTe NP on the innate immune system. The human monocyte cell line THP-1 was employed as a model. The anticancer drugs camptothecin and doxorubicin were used as positive controls for cell death, and lipopolysaccharide was chosen as a positive control for proinflammatory activation. Despite equivalent overall toxicity effect (50 ± 10% dead cells), the three NP induced distinctly different proteomics signatures, with the strongest effect being induced by CdTe NP, followed by CuO and gold NP. The CdTe toxicity mechanism involves down-regulation of topoisomerases. The effect of CuO NP is most reminiscent of oxidative stress and involves up-regulation of proteins involved in heat response. The gold NP induced up-regulation of the inflammatory mediator, NF-κB, and its inhibitor TIPE2 was identified as a direct target of gold NP. Furthermore, gold NP triggered activation of NF-κB as evidenced by phosphorylation of the p65 subunit. Overall, the combined proteomics approach described here can be used to characterize the effects of NP on immune cells.

Topics: Cadmium Compounds; Camptothecin; Cell Proliferation; Cell Survival; Copper; Cytotoxins; Doxorubicin; Gold; Humans; Immunity, Innate; Inflammation; Lipopolysaccharides; Metal Nanoparticles; Monocytes; Oxidative Stress; Proteome; Proteomics; Tellurium

Nanobiosynthesis belongs to the most recent methods for synthesis of nanoparticles. This type of synthesis provides many advantages including the uniformity in particle shape and size. The biosynthesis has also a significant advantage regarding chemical properties of the obtained particles. In this study, we characterized the basic properties and composition of quantum dots (QDs), obtained by the extracellular biosynthesis by Escherichia coli. Furthermore, the toxicity of the biosynthesized QDs was compared to QDs prepared by microwave synthesis. The obtained results revealed the presence of cyan CdTe QDs after removal of substantial amounts of organic compounds, which stabilized the nanoparticle surface. QDs toxicity was evaluated using three cell lines Human Foreskin Fibroblast (HFF), Human Prostate Cancer cells (PC-3) and Breast Cancer cells (MCF-7) and the MTT assay. The test revealed differences in the toxicity between variants of QDs, varying about 10% in the HFF and 30% in the MCF-7 cell lines. The toxicity of the biosynthesized QDs to the PC-3 cell lines was about 35% lower in comparison with the QDs prepared by microwave synthesis.

Topics: Cadmium Compounds; Cell Line; Cell Survival; Escherichia coli; Humans; Quantum Dots; Tellurium

In the present research, a sensitive biosensing method was proposed for the detection of trace amounts of ascorbic acid (AA). Herein, colloidal silver nanoparticles (SNPs) were successfully in-situ produced by chemical reduction of silver ion in the presence of AA, as a reducing agent. The one-pot in-situ produced silver nanoparticles were characterized by UV-vis, dynamic light scattering (DLS), zeta potential and transmission electron microscopic (TEM). SNPs act as a strong fluorescence quencher for the CdTe quantum dots via an inner filter effect (IFE). Since the absorption band of SNPs entirely covered both emission and excitation bands of QDs. Therefore, the decreasing in the fluorescence signal depends on the AA concentration in the linear range of 0.2-88.0ngmL

Topics: Ascorbic Acid; Cadmium Compounds; Humans; Metal Nanoparticles; Quantum Dots; Tellurium

Topics: 3-Mercaptopropionic Acid; Biosensing Techniques; Cadmium Compounds; Fluorescent Dyes; Humans; Limit of Detection; Mercaptopurine; Organometallic Compounds; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Arsenic (As

Topics: Arsenic; Biosensing Techniques; Cadmium Compounds; Fluorescence; Fluorescent Dyes; Luminescence; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

A very sensitive and convenient nanobiosensor based on fluorescence resonance energy transfer (FRET) was developed for the detection of a 22-mer oligonucleotides sequence in Human Papillomavirus 18 virus (HPV18) gene. For this purpose, water-soluble CdTe quantum dots (QDs) were synthesized and, subsequently, amino-modified 11-mer oligonucleotide as one of the two necessary probes was attached to QDs surface to form functional QDs-DNA conjugates. Right after addition of the QDs-DNA and a second Cyanine5 (Cy5)-labeled 11-mer oligonucleotide probe to the DNA target solution, the sandwiched hybrids were formed. The resulting hybridization brings the Cy5 fluorophore as the acceptor to close proximity of the QDs as donor, so that an effective transfer of energy from the excited QDs to the Cy5 probe would occur via FRET processing. The fluorescence intensity of Cy5 found to linearly enhance by increasing the DNA target concentration from 1.0 to 50.0nM, with a detection limit of 0.2nM. This homogeneous DNA detection method does not require excessive washing and separation steps of un-hybridized DNA, due to the fact that no FRET can be observed when the probes are not ligated. Finally, feasibility and selectivity of the proposed one-spot DNA detection nanobiosensor were investigated by analysis of derived nucleotides from HPV18 and mismatched sequences.

Topics: Biosensing Techniques; Cadmium Compounds; DNA, Viral; Fluorescence Resonance Energy Transfer; Human papillomavirus 18; Nanotechnology; Oligonucleotides; Quantum Dots; Reproducibility of Results; Sensitivity and Specificity; Tellurium; Thioglycolates

Despite recent advances in thermometry, determination of temperature at the nanometer scale in single molecules to live cells remains a challenge that holds great promise in disease detection among others. In the present study, we use a new approach to nanometer scale thermometry with a spatial and thermal resolution of 80 nm and 1 mK respectively, by directly associating 2 nm cadmium telluride quantum dots (CdTe QDs) to the subject under study. The 2 nm CdTe QDs physically adhered to bovine cardiac and rabbit skeletal muscle myosin, enabling the determination of heat released when ATP is hydrolyzed by both myosin motors. Greater heat loss reflects less work performed by the motor, hence decreased efficiency. Surprisingly, we found rabbit skeletal myosin to be more efficient than bovine cardiac. We have further extended this approach to demonstrate the gain in efficiency of Drosophila melanogaster skeletal muscle overexpressing the PGC-1α homologue spargel, a known mediator of improved exercise performance in humans. Our results establish a novel approach to determine muscle efficiency with promise for early diagnosis and treatment of various metabolic disorders including cancer.

Topics: Adenosine Triphosphate; Animals; Cadmium Compounds; Cardiac Myosins; Cattle; Drosophila melanogaster; Fluorescence; Hydrolysis; Male; Muscle, Skeletal; Nanotechnology; Particle Size; Quantum Dots; Rabbits; Skeletal Muscle Myosins; Surface Properties; Tellurium; Temperature; Thermometry

As the early detection and total destruction of gliomas are essential for longer survival, we attempted to synthesize a quantum dot (QD) that is capable of recognizing glioma cells for imaging and photodynamic therapy.. Using a one-pot aqueous approach, near infrared-emitting CdTe was produced. After detection of its physicochemical characteriistics, it was conjugated with RGD. The emission images were observed with confocal microscopy. To test its toxicity, CdTe-RGD at various concentrations was separately added to a human glioma cell line (U251) and a mouse embryo fibroblast cell line (3T3) (control) for incubation in dark conditions. To test its photodynamic effect, the U251 and 3T3 cells were then irradiated for 5-60 min, using a 632.8-nm laser.. This QD (Φ = 3.75 nm, photoluminescence (PL) peak wavelength = 700 nm, photoluminescence quantum yield (PLQY) = 20 %), was a spherical crystal with excellent monodispersity. Under a confocal microscope, U251 cells were visualized, but not the 3T3 cells. In dark conditions, the survival rates of both U251 and 3T3 cells were above 85 %. After laser irradiation, the survival rate of U251 cells decreased to 37 ± 1.6 % as the irradiation time and the CdTe-RGD concentration were increased.. With good physicochemical characteriistics and low toxicity, this QD-RGD has broad prospects for use in the biomedical imaging and photodynamic therapy of gliomas.

Topics: 3T3 Cells; Animals; Antineoplastic Agents; Brain Neoplasms; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Glioblastoma; Glioma; Humans; In Vitro Techniques; Low-Level Light Therapy; Mice; Microscopy, Confocal; Oligopeptides; Photochemotherapy; Quantum Dots; Tellurium

Endometriosis is difficult to treat since the side effects of the current therapeutic method and the high recurrence rate; thus, newer and safer therapeutic approaches are urgently needed. This work investigates the enhanced permeability and retention effect of CdTe quantum dots (QDs) and hollow gold nanospheres (HAuNS) in endometriosis to increase the delivery of HAuNS into lesion cells. The surface of HAuNS is successfully conjugated with a TNYL peptide that has specific affinity for the EphB4 receptor, which is a member of the Eph family of receptor tyrosine kinases. It is found that the EphB4 receptor is overexpressed in endometriosis lesions. The data indicate that both QDs and HAuNS can efficiently accumulate in endometriotic lesions through permeable vessels and the TNYL-conjugated HAuNS (TNYL-HAuNS) accumulate more via the interaction with EphB4. The specific photothermal ablation therapy based on TNYL-HAuNS significantly inhibits the growth of the endometriotic volume and induces the atrophy and degeneration of ectopic endometrium with no detectable toxicity to the normal organs. The level of TNF-α and estradiol also significantly decreases in the endometriotic lesions, indicating that the treatment enables a recovery from hormonal imbalance and inflammatory injury. This work can be a valuable reference for future endometriosis therapy.

Topics: Ablation Techniques; Animals; Cadmium Compounds; Disease Models, Animal; Endometriosis; Female; Gold; Hyperthermia, Induced; Mice; Nanospheres; Peptides; Phototherapy; Quantum Dots; Receptor, EphB4; Tellurium; Tissue Distribution; Treatment Outcome

We report a rapid and facile resonance light scattering (RLS) technique that utilizes CdTe quantum dots (CdTe QDs) probe to detect microRNA-122. The RLS sensor is ingeniously designed with P1 and P2, two cDNA sequence probes with partially complementary sequences to miRNA-122. The amine-modified P1 and P2 are coupled to the surface of QDs to form functional QDs-P1 and QDs-P2 conjugates, which are collectively referred to as QDs-P. The cDNAs hybridize with the target miRNA to rapidly induce the self-assembly of QDs probe and change RLS intensity. The proposed technique can detect miRNA-122 within 40min. RLS intensity is enhanced in proportion with miRNA-122 concentrations of 0.16-4.80nM and has a low detection limit of 9.4pM. In addition, the assay satisfactorily detects miRNAs in human serum samples. Thus, the assay has considerable potential for the analysis of other interesting tumor makers.

Topics: Biosensing Techniques; Cadmium Compounds; Dynamic Light Scattering; Humans; MicroRNAs; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Topics: Cadmium Compounds; Fluorescent Dyes; Mercury; Optical Phenomena; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

The inhibitory effects of CdTe/ZnS quantum dots (QDs) modified with 3-mercaptopropionic acid (negatively charged) or cysteamine (positively charged) on the metabolic activity of Escherichia coli were investigated using biological microcalorimetry. Results show that the inhibitory ratio of positive QDs is higher than that of negative QDs. Transmission electron microscopy images indicate that QDs are prone to be adsorbed on the surface of E. coli. This condition disturbs the membrane structure and function of E. coli. Fluorescence anisotropy results demonstrate that positive QDs show a significant increase in the membrane fluidity of E. coli and dipalmitoylphosphatidylcholine (DPPC) model membrane. Furthermore, fluorescence anisotropy values of DPPC membrane in the gel phase decreased upon the addition of positive QDs. By contrast, anisotropy values in the liquid-crystalline phase are almost constant. The change in membrane fluidity is associated with the increased permeability of the membrane. Finally, the kinetics of dye leakage from liposomes demonstrate that the surface charge of QDs is crucial to the interaction between QDs and membrane.

Topics: Cadmium Compounds; Cell Membrane; Escherichia coli; Microscopy, Electron, Transmission; Particle Size; Quantum Dots; Sulfides; Surface Properties; Tellurium; Zinc Compounds

With the increasing concern of potential health and environmental risk, it is essential to develop reliable methods for transgenic soybean detection. Herein, a simple, sensitive and selective assay was constructed based on homogeneous fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) and multiwalled carbon nanotubes@graphene oxide nanoribbons (MWCNTs@GONRs) to form the fluorescent "on-off-on" switching for simultaneous monitoring dual target DNAs of promoter cauliflower mosaic virus 35s (P35s) and terminator nopaline synthase (TNOS) from transgenic soybean. The capture DNAs were immobilized with corresponding QDs to obtain strong fluorescent signals (turning on). The strong π-π stacking interaction between single-stranded DNA (ssDNA) probes and MWCNTs@GONRs led to minimal background fluorescence due to the FRET process (turning off). The targets of P35s and TNOS were recognized by dual fluorescent probes to form double-stranded DNA (dsDNA) through the specific hybridization between target DNAs and ssDNA probes. And the dsDNA were released from the surface of MWCNTs@GONRs, which leaded the dual fluorescent probes to generate the strong fluorescent emissions (turning on). Therefore, this proposed homogeneous assay can be achieved to detect P35s and TNOS simultaneously by monitoring the relevant fluorescent emissions. Moreover, this assay can distinguish complementary and mismatched nucleic acid sequences with high sensitivity. The constructed approach has the potential to be a tool for daily detection of genetically modified organism with the merits of feasibility and reliability.

Topics: Amino Acid Oxidoreductases; Biosensing Techniques; Cadmium Compounds; Caulimovirus; DNA, Plant; DNA, Viral; Fluorescence Resonance Energy Transfer; Glycine max; Graphite; Immobilized Nucleic Acids; Nanotubes, Carbon; Oxides; Plant Proteins; Plants, Genetically Modified; Quantum Dots; Reproducibility of Results; Tellurium

Quantum dots (QDs) could be used in the field of biology and medicine as excellent nano-scale fluorescent probes due to their unique optical properties, but the adverse effects of QDs are always the obstruction for its usage in living organisms. In this study, we observed that CdTe QDs exposure decreased the cell viability while increased the apoptosis rates in the L929 cells. Apart from QD-induced oxidative stress indicated by excessive ROS generation, three signal transductions, including Akt, p38 and JNK, played important roles on the regulation of cell apoptosis by CdTe QDs exposure as well. In order to reduce the toxicity of CdTe QDs, we explored the protective effects of three treatments, i.e. resveratrol, H

Topics: Animals; Apoptosis; Cadmium Compounds; Cell Line; Cell Survival; Hydrogen Sulfide; Hyperthermia, Induced; MAP Kinase Kinase 4; Mice; p38 Mitogen-Activated Protein Kinases; Protective Agents; Proto-Oncogene Proteins c-akt; Quantum Dots; Reactive Oxygen Species; Resveratrol; Signal Transduction; Stilbenes; Tellurium

CdTe/ZnSe core/shell quantum dot (QD), one of the strongest and most highly luminescent nanoparticles, was directly synthesized in an aqueous medium to study its individual interactions with important nucleobases (adenine, guanine, cytosine, and thymine) in detail. The results obtained from the optical analyses indicated that the interactions of the QDs with different nucleobases were different, which reflected in different fluorescent emission maxima and intensities. The difference in the interaction was found due to the different chemical behavior and different sizes of the formed nanoconjugates. An electrochemical study also confirmed that the purines and pyrimidines show different interactions with the core/shell QDs. Based on these phenomena, a novel QD-based method is developed to detect the presence of the DNA, damage to DNA, and mutation. The QDs were successfully applied very easily to detect any change in the sequence (mutation) of DNA. The QDs also showed their ability to detect DNAs directly from the extracts of human cancer (PC3) and normal (PNT1A) cells (detection limit of 500 pM of DNA), which indicates the possibilities to use this easy assay technique to confirm the presence of living organisms in extreme environments.

Topics: Cadmium Compounds; Cell Line, Tumor; DNA; DNA Damage; Dynamic Light Scattering; Electrochemical Techniques; Humans; Mutation; Quantum Dots; Selenium Compounds; Spectroscopy, Fourier Transform Infrared; Static Electricity; Tellurium; Zinc Compounds

Tumor therapy using nanoparticles (NPs) is mainly aimed at using the NPs as carriers for therapeutic drugs or as mediators for external stimuli to generate heat. Recent studies have shown that the toxicity of NPs can also be specifically exploited to kill cancer cells. In the present work, we employ core-only CdTe quantum dots and study their cytotoxicity using a validated high-content screening approach. The data revealed a clear correlation between toxicity and quantum dot degradation, which could be monitored through loss of fluorescence intensity. Based on the in vitro data obtained, the in vivo dose was calculated relative to the estimated number of tumor cells based on luminescence measurements. The obtained results show a clear increase in reproducibility of the therapeutic effect compared to normal conditions, where a set dose of quantum dots was administered regardless of the tumor size. The therapeutic delivery could also be monitored in vivo, where the loss of fluorescence intensity correlated with the anticancer efficacy. The present work highlights the benefits of noninvasive imaging to monitor therapeutic delivery and to optimize treatment via personalized medicine.

Topics: Animals; Cadmium Compounds; Cell Death; Cell Line, Tumor; Cell Proliferation; Drug Delivery Systems; Female; Fluorescence; Humans; Luciferases; Luminescent Measurements; Mice; Models, Theoretical; Neoplasms; Optical Imaging; Precision Medicine; Quantum Dots; Tellurium

A sensitive and simple method for the determination of enoxacin (ENX) was developed based on the fluorescence quenching effect of ENX for glutathione (GSH)-capped CdTe quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 4.333 × 10(-9)  mol⋅L(-1) to 1.4 × 10(-5)  mol⋅L(-1) with a correlation coefficient (R) of 0.9987, and the detection limit (3σ/K) was 1.313 × 10(-9)  mol⋅L(-1). The corresponding mechanism has been proposed on the basis of electron transfer supported by ultraviolet-visible (UV) light absorption, fluorescence spectroscopy, and the measurement of fluorescence lifetime. The method has been applied to the determination of ENX in pharmaceutical formulations (enoxacin gluconate injections and commercial tablets) with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

Topics: Cadmium Compounds; Chemistry, Pharmaceutical; Enoxacin; Fluorescence; Glutathione; Pharmaceutical Preparations; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

Stable photoluminescence QD light-emitting diodes (QD-LEDs) were made based on hydrophilic CdTe quantum dots (QDs). A quantum dot-inorganic nanocomposite (hydrophilic CdTe QDs incorporating dehydrated silica gel) was prepared by two methods (rotary evaporation and freeze drying). Taking advantage of its viscosity, plasticity and transparency, dehydrated silica gel could be coated on the surface of ultraviolet (UV) light LEDs to make photoluminescence QD-LEDs. This new photoluminescence QD-LED, which is stable, environmentally non-toxic, easy to operate and low cost, could expand the applications of hydrophilic CdTe QDs in photoluminescence.

Topics: Cadmium Compounds; Gels; Hydrophobic and Hydrophilic Interactions; Light; Luminescence; Photochemical Processes; Quantum Dots; Silicon Dioxide; Tellurium

A rapid, simple and inexpensive spectrofluorimetric sensor for determination of doxycycline based on its interaction with thioglycolic acid-capped cadmium telluride quantum dots (TGA/CdTe QDs) has been developed. Under the optimum experimental conditions, the sensor exhibited a fast response time of <10s. The results revealed that doxycycline could quench the fluorescence of TGA/CdTe QDs via electron transfer from the QDs to doxycycline through a dynamic quenching mechanism. The sensor permitted determination of doxycycline in a concentration range of 1.9×10(-6)-6.1×10(-5)molL(-1) with a detection limit of 1.1×10(-7)molL(-1). The sensor was applied for determination of doxycycline in honey and human serum samples.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Doxycycline; Honey; Humans; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thioglycolates

The LCC-CdTe quantum dots (QDs) hybrid was fabricated by mixing the N-lauryl-N, O-carboxymethyl chitosan (LCC) micelle with water-soluble CdTe QDs in an aqueous solution via hydrophobic forces and the electronic attraction. The structures of LCC and LCC-CdTe QDs hybrid were determined by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The results showed that the lauryl and carboxymethyl were successfully grafted to chitosan oligosaccharide (CSO), and a number of CdTe QDs were encapsulated by LCC micelle to form a core/shell structure. The tested results of the fluorescent characteristics of LCC, CdTe QDs and LCC-CdTe QDs hybrid showed that there were some obvious fluorescent interactions between LCC and CdTe QDs. Meanwhile, with the change in LCC space structure, the fluorescent interactions between LCC and QDs showed different fluorescent characteristics. The QDs fluorescent (FL) intensity increased first and then decreased to almost quenching, while LCC FL intensity decreased continually.

Topics: Cadmium Compounds; Chitosan; Fluorescence; Fluorescent Dyes; Quantum Dots; Solubility; Tellurium; Water

CdTe quantum dots (QDs) capped with different stabilizers, i.e. thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA) and glutathione (GSH) were investigated as fluorescent probes for the determination of Cu(2+). The stabilizer was shown to play an important role in both the sensitivity and selectivity for the determination of Cu(2+). TGA-capped CdTe QDs showed the highest sensitivity, followed by the MPA and GSH-capped CdTe QDs, respectively. The TGA- and MPA-capped CdTe QDs were not selective for Cu(2+) that was affected by Ag(+). The GSH-capped CdTe QDs were insensitive to Ag(+) and were used to determine Cu(2+) in water samples. Under optimal conditions, quenching of the fluorescence intensity (F0/F) increased linearly with the concentration of Cu(2+) over a range of 0.10-4.0 µg/mL and the detection limit was 0.06 µg/mL. The developed method was successfully applied to the determination of Cu(2+) in water samples. Good recoveries of 93-104%, with a relative standard deviation of < 6% demonstrated that the developed simple method was accurate and reliable. The quenching mechanisms were also described.

Topics: Cadmium Compounds; Copper; Fluorescence; Fluorescent Dyes; Hydrogen-Ion Concentration; Ions; Molecular Structure; Quantum Dots; Sulfhydryl Compounds; Tellurium; Water; Water Pollutants, Chemical

We report a fluorescence resonance energy transfer (FRET) system in which the fluorescent donor is fluorescein isothiocyanate (FITC) dye and the fluorescent acceptor is CdTe quantum dot (QDs). Based on FRET quenching theory, we designed a method to detect the concentration of silver ions (Ag(+)). The results revealed a good linear trend over Ag(+) concentrations in the range 0.01-8.96 nmol/L, a range that was larger than with other methods; the quenching coefficient is 0.442. The FRET mechanism and physical mechanisms responsible for dynamic quenching are also discussed.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Ions; Isothiocyanates; Quantum Dots; Silver; Tellurium

In this paper, a new fluorescence bioassay for Golgi protein-73 (GP73), a promising marker for monitoring liver tumor, was developed by using anti-GP73 antibody (GP73 Ab) capped quantum dots (QDs) coupled with protein A/G agarose beads in an attempt to improve the analysis time, cost and operation. First, carboxylic-functionalized Mn modified CdTe/CdS QDs were synthesized and covalently conjugated with GP73 Ab, then protein A/G agarose beads were specifically combined with the QDs-conjugated Ab to form the QDs-Ab-beads conjugate, which could capture and separate GP73 from the sample through simple centrifugation. It was found that the fluorescence intensity of the above QDs-Ab-beads biosensor could be specifically quenched by GP73 added. A simple, rapid and specific quantitative method for GP73 protein was proposed using the as-prepared QDs-Ab-beads as a biosensor. Under the optimized conditions, the calibration curve of the proposed assay showed good linearity with a correlation coefficient of 0.9935 in the concentration range of 20-150 ng/mL of GP73 protein. The limit of detection (defined as 3σ/K) was 10 ng/mL. The method built exhibited a great potential in the clinic test of GP73.

Topics: Biosensing Techniques; Cadmium Compounds; Humans; Immunoassay; Manganese; Membrane Proteins; Quantum Dots; Sulfides; Tellurium

To date, several fluorescent probes modified by a single targeting agent have been explored. However, studies on the preparation of dual-function quantum dot (QD) fluorescent probes with dual-targeting action and a therapeutic effect are rare. Here, a dual-targeting CdTe/CdS QD fluorescent probe with a bovine serum albumin-glycyrrhetinic acid conjugate and arginine-glycine-aspartic acid was successfully prepared that could induce the apoptosis of liver cancer cells and showed enhanced targeting in in vitro cell imaging. Therefore, the as-prepared fluorescent probe in this work is an efficient diagnostic tool for the simultaneous detection of liver cancer and breast cancer cells.

Topics: Animals; Apoptosis; Breast Neoplasms; Cadmium Compounds; Cattle; Cell Survival; Cells, Cultured; Female; Fluorescence; Fluorescent Dyes; Glycyrrhetinic Acid; Humans; Liver Neoplasms; Oligopeptides; Quantum Dots; Serum Albumin, Bovine; Tellurium

A convenient enzymatic optical method for uric acid detection was developed based on the fluorescence quenching of ligand-capped CdTe nanoparticles by H2O2 which was generated from the enzymatic reaction of uric acid. The interactions between the CdTe nanoparticles capped with different ligands (glutathione, 3-mercaptopropionic acid, and thioglycerol) and H2O2 were investigated. The fluorescence quenching studies of GSH-capped CdTe nanoparticles demonstrated an excellent sensitivity to H2O2. The effects of uric acid, uricase and H2O2 on the fluorescence intensity of CdTe nanoparticles were also explored. The detection conditions, reaction time, pH value, incubation period and the concentration of uricase and uric acid were optimized. The detection limit of uric acid was found to be 0.10 µM and the linear range was 0.22-6 µM under the optimized experimental conditions. These results typify that CdTe nanoparticles could be used as a fluorescent probe for uric acid detection.

Topics: Cadmium Compounds; Fluorescent Dyes; Humans; Metal Nanoparticles; Peroxidase; Spectrometry, Fluorescence; Tellurium; Urate Oxidase; Uric Acid

A sensitive chemiluminescence (CL) sensor based on chemiluminescence resonance energy transfer (CRET) in CdTe quantum dots@luminol (CdTe QDs@luminol) nanomaterials combined with chitosan/graphene oxide-magnetite-molecularly imprinted polymer (Cs/GM-MIP) for sensing chrysoidine was developed. CdTe QDs@luminol was designed to not only amplify the signal of CL but also reduce luminol consumption in the detection of chrysoidine. On the basis of the abundant hydroxy and amino, Cs and graphene oxide were introduced into the GM-MIP to improve the adsorption ability. The adsorption capacities of chrysoidine by both Cs/GM-MIP and non-imprinted polymer (Cs/GM-NIP) were investigated, and the CdTe QDs@luminol and Cs/GM-MIP were characterized by UV-vis, FTIR, SEM and TEM. The proposed sensor can detect chrysoidine within a linear range of 1.0×10(-7) - 1.0×10(-5) mol/L with a detection limit of 3.2×10(-8) mol/L (3δ) due to considerable chemiluminescence signal enhancement of the CdTe quantum dots@luminol detector and the high selectivity of the Cs/GM-MIP system. Under the optimal conditions of CL, the CdTe QDs@luminol-Cs/GM-MIP-CL sensor was used for chrysoidine determination in samples with satisfactory recoveries in the range of 90-107%.

Topics: Adsorption; Cadmium Compounds; Chitosan; Ferrosoferric Oxide; Fluorescence Resonance Energy Transfer; Graphite; Luminescent Measurements; Luminol; Molecular Imprinting; Oxides; p-Aminoazobenzene; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium

A new approach for developing a fluorimetric aptasensor has been described and applied for determination of a highly toxic cation, As(III). In this method an aptamer was used to aggregate cationic cysteamine-stabilized CdTe/ZnS core/shell quantum dots, as a result fluorescence quenching was accrued. In the presence of As(III), the aptamer and As(III) make a complex, which prevents aggregation of the quantum dots. Thus, the fluorescence intensity of the quantum dots was enhanced upon the de-aggregation, which depends on the concentration of As(III). The fluorimetric assay has a very low detection limit of 1.3 pmolL(-1) As(III) with a dynamic range of 1.0 × 10(-11) to 1.0 × 10(-6) molL(-1). The interference effect of a wide variety of cations and anions was investigated, and the obtained results confirm high selectivity of the aptasensor for As(III) detection. The present assay was successfully applied for the determination of As(III) in several water samples.

Topics: Arsenic; Cadmium Compounds; Cysteamine; Environmental Monitoring; Equipment Design; Equipment Failure Analysis; Metal Nanoparticles; Quantum Dots; Reproducibility of Results; Selenium Compounds; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium; Water Pollutants, Chemical; Zinc Compounds

We report a study on anion exchange reaction of CdTe nanocrystals with S(2-) in aqueous solution under ambient condition. We found that the optical properties of CdTe nanocrystals can be well tuned by controlling the reaction conditions, in which the reaction temperature is crucially important. At low reaction temperature, the product nanocrystals showed blue-shifts in both absorption and PL spectra, while the photoluminescence quantum yield (PLQY) was significantly enhanced. When anion exchanges were carried out at higher reaction temperature, on the other hand, obvious red shifts in absorption and PL spectra accompanied by a fast increase followed by gradual decrease in PLQY were observed. On variation of S(2-) concentration, it was found that the overall kinetics of Te(2-) for S(2-) exchanges depends also on [S(2-)] when anion exchanges were performed at higher temperature. A possible mechanism for anion exchanges in CdTe NCs was proposed.

Topics: Anions; Cadmium Compounds; Kinetics; Nanostructures; Optical Phenomena; Particle Size; Solubility; Sulfur; Surface Properties; Tellurium; Temperature; Water

Novel CdTe/ZnS quantum dot (QD) probes based on the quenching effect were proposed for the simple, rapid, and specific determination of ammonium in aqueous solutions. The QDs were modified using 3-mercaptopropionic acid, and the fluorescence responses of the CdTe/ZnS QD probes to ammonium were detected through regularity quenching. The quenching levels of the CdTe/ZnS QDs and ammonium concentration showed a good linear relationship between 4.0 × 10(-6) and 5.0 × 10(-4) mol/L; the detection limit was 3.0 × 10(-7) mol/L. Ammonium contents in synthetic explosion soil samples were measured to determine the practical applications of the QD probes and a probable quenching mechanism was described. Copyright © 2015 John Wiley & Sons, Ltd.

Topics: Ammonium Compounds; Cadmium Compounds; Fluorescent Dyes; Particle Size; Quantum Dots; Sulfides; Surface Properties; Tellurium; Zinc Compounds

A rapid, simple and sensitive label-free fluorescence method was developed for the determination of trace amounts of an important drug, heparin. This new method was based on water-soluble glutathione-capped CdTe quantum dots (CdTe QDs) as the luminescent probe. CdTe QDs were prepared according to the published protocol and the sizes of these nanoparticles were verified through transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS) with an average particle size of about 7 nm. The fluorescence intensity of glutathione-capped CdTe QDs increased with increasing heparin concentration. These changes were followed as the analytical signal. Effective variables such as pH, QD concentration and incubation time were optimized. At the optimum conditions, with this optical method, heparin could be measured within the range 10.0-200.0 ng mL(-1) with a low limit of detection, 2.0 ng mL(-1) . The constructed fluorescence sensor was also applied successfully for the determination of heparin in human serum. Copyright © 2015 John Wiley & Sons, Ltd.

Topics: Cadmium Compounds; Fluorescence; Healthy Volunteers; Heparin; Humans; Hydrogen-Ion Concentration; Luminescent Measurements; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium

Ligands used on the surface of colloidal nanoparticles (NPs) have a significant impact on physiochemical properties of NPs and their interaction in biological environments. In this study, we report a one-pot aqueous synthesis of 3-mercaptopropionic acid (MPA)-functionalized CdTe/CdS/ZnS quantum dots (Qdots) in the presence of thiol-terminated methoxy polyethylene glycol (mPEG) molecules as a surface coordinating ligand. The resulting mPEG-Qdots were characterized by using ζ potential, FTIR, thermogravimetric (TG) analysis, and microscale thermophoresis (MST) studies. We investigated the effect of mPEG molecules and their grafting density on the Qdots photophysical properties, colloidal stability, protein binding affinity, and in vitro cellular toxicity. Moreover, cellular binding features of the resulting Qdots were examined by using three-dimensional (3D) tumor-like spheroids, and the results were discussed in detail. Promisingly, mPEG ligands were found to increase colloidal stability of Qdots, reduce adsorption of proteins to the Qdot surface, and mitigate Qdot-induced side effects to a great extent. Flow cytometry and confocal microscopy studies revealed that PEGylated Qdots exhibited distinctive cellular interactions with respect to their mPEG grafting density. As a result, mPEG molecules demonstrated a minimal effect on the ZnS shell deposition and the Qdot fluorescence efficiency at a low mPEG density, whereas they showed pronounced effect on Qdot colloidal stability, protein binding affinity, cytotoxicity, and nonspecific binding at a higher mPEG grafting amount.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Cattle; Cell Line; Cell Survival; Colloids; Humans; Polyethylene Glycols; Protein Aggregates; Quantum Dots; Serum Albumin, Bovine; Sulfides; Tellurium; Water; Zinc Compounds

A low-cost, simple, and highly selective analytical method was developed for sensitive visual detection of selenium in human urine both outdoors and at home, by coupling hydride generation with headspace solid-phase extraction using quantum dots (QDs) immobilized on paper. The visible fluorescence from the CdTe QDs immobilized on paper was quenched by H2Se from hydride generation reaction and headspace solid-phase extraction. The potential mechanism was investigated by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) as well as Density Functional Theory (DFT). Potential interferences from coexisting ions, particularly Ag(+), Cu(2+), and Zn(2+), were eliminated. The selectivity was significantly increased because the selenium hydride was effectively separated from sample matrices by hydride generation. Moreover, due to the high sampling efficiency of hydride generation and headspace solid phase extraction, the sensitivity and the limit of detection (LOD) were significantly improved compared to conventional methods. A LOD of 0.1 μg L(-1) and a relative standard deviation (RSD, n = 7) of 2.4% at a concentration of 20 μg L(-1) were obtained when using a commercial spectrofluorometer as the detector. Furthermore, a visual assay based on the proposed method was developed for the detection of Se, 5 μg L(-1) of selenium in urine can be discriminated from the blank solution with the naked eye. The proposed method was validated by analysis of certified reference materials and human urine samples with satisfactory results.

Topics: Animals; Cadmium Compounds; Dogfish; Hair; Humans; Muscles; Paper; Quantum Dots; Quantum Theory; Selenium; Solid Phase Extraction; Tellurium

Multimodal imaging has made great contribution for diagnosis and therapy of disease since it can provide more effective and complementary information in comparison to any single imaging modality. The design and fabrication of fluorescent-magnetic nanoparticles for multimodal imaging has rapidly developed over the years. Herein, we demonstrate the facile synthesis of GdS coated CdTe nanoparticles (CdTe@GdS NPs) as multimodal agents for fluorescence (FL) and T1-weighted magnetic resonance (MR) imaging. These nanoparticles obtain both prominent fluorescent and paramagnetic properties by coating the GdS shell on the surface of CdTe core via a simple room-temperature route in aqueous solution directly. It is shown that the as-prepared CdTe@GdS NPs have high quantum yield (QY) value of 12% and outstanding longitudinal relaxation rate (r1) of 11.25 mM s(-1), which allow them to be employed as FL/MR dual-modal imaging contrast agents. They also exhibit small particle size of 5 nm, excellent colloidal stability and low cellular toxicity for concentrations up to 750 μg mL(-1). In addition, with the conjugation of folic acid, the nanoparticles were successfully used for tumor-targeted FL/MR dual-modal imaging in vitro and in vivo.

Topics: Animals; Cadmium Compounds; Cell Survival; Fluorescent Dyes; Gadolinium; Humans; KB Cells; Magnetite Nanoparticles; Mice; Mice, Inbred BALB C; Mice, Nude; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Neoplasms; Spectroscopy, Fourier Transform Infrared; Sulfides; Tellurium

An optical biosensing method using CdTe quantum dots (QDs) and bi-enzyme-immobilized eggshell membranes for the determination of organophosphorus pesticides (OPs) has been developed. Increasing amounts of OPs led to a decrease of the enzymatic activity and thus a decrease in the production of hydrogen peroxide (H2O2), which can quench the fluorescence of the CdTe QDs. Under the optimum conditions, there was a good linear relationship between the enzyme inhibition percentage and the logarithm of paraoxon or parathion concentration in the range of 1.0 × 10(-11)-1.0 × 10(-6) mol L(-1). The detection limit (S/N = 3) of the proposed biosensors were as low as 4.30 × 10(-12) mol L(-1) for paraoxon and 2.47 × 10(-12) mol L(-1) for parathion. The bi-enzyme-immobilized eggshell membrane demonstrated a long shelf-life of at least 2 months and the results showed good repeatability. The proposed method was successfully applied to the determination of the OPs in real fruit samples with satisfactory results.

Topics: Acetylcholinesterase; Alcohol Oxidoreductases; Animals; Biosensing Techniques; Cadmium Compounds; Egg Shell; Enzymes, Immobilized; Fruit; Hydrogen Peroxide; Limit of Detection; Luminescent Measurements; Membranes; Organophosphorus Compounds; Pesticides; Quantum Dots; Tellurium

Multidrug therapy may yield higher therapeutic effects as compared to monotherapy, yet its wide application has been hampered by the limitations of conventional drug delivery systems, in which not only incompatible drugs cannot be co-delivered but also the release rates of individual co-delivered drugs cannot be tuned separately. Regarding these limitations, we adopt the microfluidic electrospray technology to fabricate alginate-based multicompartment microgel beads. By using cadmium-telluride (CdTe) quantum dots (QDs) and a quenching agent as a model pair, the beads are shown to effectively separate incompatible drugs during co-delivery, and significantly prolong the time of observable fluorescence emission from QDs co-delivered with a quenching agent. Moreover, the drug release rates from different compartments can be tuned using the polymer blending technique to achieve a variety of drug release patterns. This study is one of the first to adopt the microfluidic electrospray technology to generate microgel beads with such versatility for co-delivery of multiple drugs. Our results provide evidence for the promising potential of our beads to be further developed as a carrier for multidrug therapy and other applications that require co-administration of multiple bioactive agents.

Topics: 3T3 Cells; Animals; Cadmium Compounds; Cell Survival; Drug Delivery Systems; Drug Liberation; Gels; HEK293 Cells; Humans; Mice; Microspheres; Pharmaceutical Preparations; Quantum Dots; Spectroscopy, Fourier Transform Infrared; Tellurium

This paper develops a new approach to enhance the electrochemiluminescence (ECL) emission of the Ru(bpy)3(2+)-tripropyl amine (TPrA) system for ultrasensitive determination of ochratoxin A (OTA). Ru(bpy)3(2+)-doped silica nanoparticles (RuSi NPs) act as ECL materials, which are immobilized on the surface of electrode by chitosan to fabricate a solid-state ECL sensor. CdTe quantum dots (QDs) can enhance the ECL emission of the Ru(bpy)3(2+)-TPrA ECL system by energy transfer. This strategy can improve the sensitivity of the sensor. In this assay, we combine the ECL with molecular imprinting technique to improve the selectivity of this sensor. The template molecule could be eluted from the molecularly imprinted polymer (MIP), and the formed cavities could then selectively recognize the target. The cavities could also work as the tunnel for the transfer of coreactant TPrA to produce responsive signal. With the increase of the concentration of OTA in samples, more cavities were filled because of the rebinding of OTA to the MIP surface, resulting in a gradual decrease in ECL intensity. The results showed that the ECL decrease value depended linearly on the logarithm of the OTA concentration in the range from 1.00×10(-5) to 11.13 ng mL(-1) with lower detection limit of 3.0 fg mL(-1) (S/N=3). This ECL sensor has also been applied to detect OTA concentration in the real samples with satisfied results, and the recoveries range from 85.1% to 107.9%.

Topics: Aspergillus; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Energy Transfer; Humans; Luminescence; Luminescent Measurements; Mycotoxins; Nanoparticles; Ochratoxins; Penicillium; Quantum Dots; Ruthenium; Silicon Dioxide; Tellurium; Zea mays

In the work, a fluorescence switch sensor consists of Mn-doped CdTe quantum dots (QDs) - methyl viologen (MV(2+)) nanohybrid is fabricated. In the sensor, MV(2+) plays a role in turning the QDs fluorescence to the "OFF" state due to the efficient electron transfer process while glutathione (GSH) could turn "ON" the native QDs fluorescence by effectively releasing QDs from the QDs-MV(2+) nanohybrids. In addition, the recovery level of QDs fluorescence is closely related to the amount of GSH. Based on this phenomenon, a reliable and convenient GSH quantitative determination method is established, which not only has a wide determination range of 1.2-200 μM, a low detection limit of 0.06 μM and a short detection time but also can realize the selective detection of GSH upon other competitive biothiols (homocysteine and cysteine) that are coexistent in biological systems. The developed sensor will greatly benefit to the study of GSH amount, helping the understanding of its function in biological systems.

Topics: Biosensing Techniques; Cadmium Compounds; Electron Transport; Fluorescence; Glutathione; Herbicides; Manganese; Nanostructures; Paraquat; Quantum Dots; Spectrometry, Fluorescence; Tellurium

In this study, we report the design and delivery of tumor-targeted, quantum dot (QD) and doxorubicin (DOX)-encapsulated PEG-PLGA nanopolymersomes (NPs) for the imaging and chemotherapy of breast cancer. To achieve active cancer targeting, QD and DOX-encapsulated NPs were conjugated with folate for folate-binding protein receptor-guided delivery, which overexpressed in many cancer cells. Hydrophobic DOX and hydrophilic MSA-capped QD were encapsulated in the bilayer and core of the PEG-PLGA nanopolymersomes, respectively. The data show that the formulated NPs sustained DOX release for a period of 12 days. Fluorescence microscopy and MTT assay demonstrated that the developed folate-targeted DOX-QD NPs had higher cytotoxicity than non-targeted NPs and the free form of the drug; moreover, they preferentially accumulated in 4T1 and MCF-7 cells in vitro. In vivo experiments including whole organ tissue-homogenate analysis and organ fluorescence microscopy imaging of BALB/c mice bearing 4T1 breast adenocarcinoma showed that the folate receptor-targeted QD encapsulated NPs accumulate at tumor sites 6h following intravenous injection. Acute toxicity studies of the prepared targeted QD-loaded NPs showed no evidence of long-term harmful histopathological and physiological effects on the treated animals. The in vivo tumor inhibitory effect of folic acid (FA)-QD-DOX NPs demonstrated an augmented therapeutic efficacy of targeted formulation over the non-targeted and free drug. The data obtained illustrate a high potential of the prepared targeted theranostic nanoplatform in the treatment and imaging of breast cancer. This study may open new directions for preparation of QD-based theranostic polymersomes for clinical application.

Topics: Adenocarcinoma; Animals; Antibiotics, Antineoplastic; Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Doxorubicin; Drug Delivery Systems; Drug Liberation; Folic Acid; Folic Acid Transporters; Humans; Mice; Mice, Inbred BALB C; Microscopy, Electron, Transmission; NIH 3T3 Cells; Polyesters; Polyethylene Glycols; Quantum Dots; Tellurium; Tumor Burden

A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Cattle; Electrochemical Techniques; Immobilized Proteins; Limit of Detection; Monophenol Monooxygenase; Quantum Dots; Serum Albumin, Bovine; Tellurium; Thrombin

Selective and sensitive detection of extracellular lactate is of fundamental significance for studying the metabolic alterations in tumor progression. Here we report the rational design and synthesis of a quantum-dot-hydrogel-based fluorescent probe for biosensing and bioimaging the extracellular lactate. By surface engineering the destabilized quantum dot sol with Nile Blue, the destabilized Nile-Blue-functionalized quantum dot sol cannot only self-assemble forming quantum dot hydrogel but also monitor lactate in the presence of nicotinamide adenine dinucleotide cofactor and lactate dehydrogenase through fluorescence resonance energy transfer. Notably, the surface engineered quantum dot hydrogel show high selectivity toward lactate over common metal ions, amino acids and other small molecules that widely coexist in biological system. Moreover, the destabilized Nile-Blue-functionalized quantum dots can encapsulate isolated cancer cells when self-assembled into a hydrogel and thus specifically detect and image the extracellular lactate metabolism. By virtue of these properties, the functionalized quantum dot hydrogel was further successfully applied to monitor the effect of metabolic agents.

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescence; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; HeLa Cells; Humans; Hydrogels; Lactic Acid; NAD; Optical Imaging; Oxazines; Quantum Dots; Tellurium

Fluorescent sensors based on semiconductor quantum dots (QDs) have been immensely investigated for achiral molecular recognition. For chiral discrimination of amino acids (AAs), we herein report a versatile fluorescent sensor, i.e., CdTe QDs encapsulated with cyclodextrin (CD) clicked silica via layer-by-layer modification. The as-obtained hybrid molecular recognition platform exhibited excellent chirality sensing of AAs at micromolar concentrations in water. By taking advantage of the inclusion complexation of CD and the optical properties of the QD core, chiral discrimination was realized on the basis of the different binding energies of the CD-AA enantiomer complexes, as revealed using density-functional theory calculation. The fluorescent probe exhibited linearly enhanced photoluminescence with increased concentration of d-histidine at 0-60 μM and L-histidine at 0-20 μM. These water-soluble fluorescent sensors using a chiral host with a covalently linked chromophore may find applications in the robust sensing of a wide range of achiral and chiral molecules in water.

Topics: Amino Acids; Cadmium Compounds; Click Chemistry; Cyclodextrins; Fluorescent Dyes; Histidine; Magnetic Resonance Spectroscopy; Metal Nanoparticles; Microscopy, Electron, Transmission; Nanoparticles; Nanotechnology; Quantum Dots; Silicon Dioxide; Solubility; Stereoisomerism; Tellurium; Water

Cadmium telluride quantum dots (CdTe QDs) have been proposed to induce oxidative stress, which plays a crucial role in CdTe QDs-mediated mitochondrial-dependent apoptosis in human umbilical vein endothelial cells (HUVECs). However, the direct interactions of CdTe QDs with HUVECs and their potential impairment of other organelles like endoplasmic reticulum (ER) in HUVECs are poorly understood. In this study, we reported that the negatively charged CdTe QDs (-21.63±0.91 mV), with good dispersity and fluorescence stability, were rapidly internalized via endocytosis by HUVECs, as the notable internalization could be inhibited up to 95.52% by energy depletion (NaN3/deoxyglucose or low temperature). The endocytosis inhibitors (methyl-β-cyclodextrin, genistein, sucrose, chlorpromazine, and colchicine) dramatically decreased the uptake of CdTe QDs by HUVECs, suggesting that both caveolae/raft- and clathrin-mediated endocytosis were involved in the endothelial uptake of CdTe QDs. Using immunocytochemistry, a striking overlap of the internalized CdTe QDs and ER marker was observed, which indicates that QDs may be transported to ER. The CdTe QDs also caused remarkable ER stress responses in HUVECs, confirmed by significant dilatation of ER cisternae, upregulation of ER stress markers GRP78/GRP94, and activation of protein kinase RNA-like ER kinase-eIF2α-activating transcription factor 4 pathway (including phosphorylation of both protein kinase RNA-like ER kinase and eIF2α and elevated level of activating transcription factor 4). CdTe QDs further promoted an increased C/EBP homologous protein expression, phosphorylation of c-JUN NH2-terminal kinase, and cleavage of ER-resident caspase-4, while the specific inhibitor (SP600125, Z-LEVD-fmk, or salubrinal) significantly attenuated QDs-triggered apoptosis, indicating that all three ER stress-mediated apoptosis pathways were activated and the direct participation of ER in the CdTe QDs-caused apoptotic cell death in HUVECs. Our findings provide important new insights into QDs toxicity and reveal potential cardiovascular risks for the future applications of QDs.

Topics: Apoptosis; beta-Cyclodextrins; Cadmium Compounds; Colchicine; eIF-2 Kinase; Endocytosis; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Fluorescence; Genistein; Heat-Shock Proteins; Human Umbilical Vein Endothelial Cells; Humans; Quantum Dots; Tellurium; Thiomalates

Chiroptical materials found in butterflies, beetles, stomatopod crustaceans, and other creatures are attributed to biocomposites with helical motifs and multiscale hierarchical organization. These structurally sophisticated materials self-assemble from primitive nanoscale building blocks, a process that is simpler and more energy efficient than many top-down methods currently used to produce similarly sized three-dimensional materials. Here, we report that molecular-scale chirality of a CdTe nanoparticle surface can be translated to nanoscale helical assemblies, leading to chiroptical activity in the visible electromagnetic range. Chiral CdTe nanoparticles coated with cysteine self-organize around Te cores to produce helical supraparticles. D-/L-Form of the amino acid determines the dominant left/right helicity of the supraparticles. Coarse-grained molecular dynamics simulations with a helical pair-potential confirm the assembly mechanism and the origin of its enantioselectivity, providing a framework for engineering three-dimensional chiral materials by self-assembly. The helical supraparticles further self-organize into lamellar crystals with liquid crystalline order, demonstrating the possibility of hierarchical organization and with multiple structural motifs and length scales determined by molecular-scale asymmetry of nanoparticle interactions.

Topics: Biomimetic Materials; Biomimetics; Cadmium Compounds; Cysteine; Models, Molecular; Nanoparticles; Nanotechnology; Stereoisomerism; Tellurium; Viruses

A simple and effective ratiometric fluorescence nanosensor for the selective detection of Cu(2+) has been developed by covalently connecting the carboxyl-modified red fluorescent cadmium telluride (CdTe) quantum dots (QDs) to the amino-functionalized blue fluorescent carbon nanodots (CDs). The sensor exhibits the dual-emissions peaked at 437 and 654 nm, under a single excitation wavelength of 340 nm. The red fluorescence can be selectively quenched by Cu(2+), while the blue fluorescence is a internal reference, resulting in a distinguishable fluorescence color change from pink to blue under a UV lamp. The detection limit of this highly sensitive ratiometric probe is as low as 0.36 nM, which is lower than the U.S. Environmental Protection Agency (EPA) defined limit (20 μM). Moreover, a paper-based sensor has been prepared by printing the hybrid carbon dots-quantum dots probe on a microporous membrane, which provides a convenient and simple approach for the visual detection of Cu(2+). Therefore, the as-synthesized probe shows great potential application for the determination of Cu(2+) in real samples.

Topics: Cadmium Compounds; Carbon; Copper; Fluorescence; Fluorescent Dyes; Ions; Limit of Detection; Nanotechnology; Nanotubes, Carbon; Paper; Porosity; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

A novel CdTe quantum dots (QDs) were prepared in aqueous phase via a facile method. At first, poly (acrylic amide) grafted onto sodium alginate (PAAm-g-SA) were successfully synthesized and then TGA capped CdTe QDs (CdTe-TGA QDs) were embed into it. The prepared CdTe-PAAm-g-SA QDs were optimized and characterized by transmission electron microscopy (TEM), thermo-gravimetric (TG) analysis, Fourier transform infrared (FT-IR), UV-vis and fluorescence spectroscopy. The characterization results indicated that CdTe-TGA QDs, with particles size of 2.90 nm, were uniformly dispersed on the chains of PAAm-g-SA biopolymer. CdTe-PAAm-g-SA QDs also exhibited excellent UV-vis absorption and high fluorescence intensity. To explore biological behavior of CdTe-PAAm-g-SA QDs, the interactions between CdTe-PAAm-g-SA QDs and human serum albumin (HSA) (or bovine serum albumin (BSA)) were investigated by cyclic voltammetry, FT-IR, UV-vis, and fluorescence spectroscopic. The results confirmed the formation of CdTe-PAAm-g-SA QDs-HSA (or BSA) complex with high binding affinities. The thermodynamic parameters (ΔG<0, ΔH<0 and ΔS<0) were indicated that binding reaction was spontaneous and van der Waals interactions and hydrogen-bond interactions played a major role in stabilizing the CdTe-PAAm-g-SA QDs-HSA (or BSA) complexes. The binding distance between CdTe-PAAm-g-SA QDs and HSA (or BSA)) was calculated about 1.37 nm and 1.27 nm, respectively, according to Forster non-radiative energy transfer theory (FRET). Analyzing FT-IR spectra showed that the formation of QDs-HSA and QDs-BSA complexes led to conformational changes of the HSA and BSA proteins. All these experimental results clarified the effective transportation and elimination of CdTe-PAAm-g-SA QDs in the body by binding to HSA and BSA, which could be a useful guideline for the estimation of QDs as a drug carrier.

Topics: Acrylic Resins; Alginates; Animals; Cadmium Compounds; Cattle; Glucuronic Acid; Hexuronic Acids; Humans; Hydrogen Bonding; Microscopy, Electron, Transmission; Particle Size; Protein Binding; Quantum Dots; Serum Albumin; Serum Albumin, Bovine; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Static Electricity; Tellurium; Temperature; Thermodynamics; Thermogravimetry

We compared biventricular ejection fractions (EFs) from gated blood-pool single-photon emission computed tomography (SPECT) using a cadmium-zinc-telluride camera (CZT-SPECT) with planar equilibrium radionuclide angiography (ERNA) using a NaI gamma camera (NaI-planar). We also evaluated whether imaging time can be reduced without compromising image quality using the CZT camera.. Forty-eight patients underwent NaI-planar and CZT-SPECT on the same day. CZT-SPECT datasets were re-projected at an LAO orientation similar to ERNA acquisition, forming CZT-repro planar datasets. The resulting biventricular volumetric measurements and EFs were compared.. LVEF calculated from CZT-SPECT and CZT-repro correlated better with NaI-planar (r = 0.93 and 0.99, respectively) than RVEF (r = 0.76 and 0.82, respectively). Excellent intra-class correlation and low bias in intra-observer comparisons were observed for the biventricular EFs derived from three datasets. A wider limit of agreement in CZT-SPECT-derived LVEFs, lower correlation and significant bias for NaI-planar, and CZT-repro-derived RVEFs was found in the inter-observer analyses. Nonetheless, the imaging time can be reduced to 4 minutes without increasing variability in EFs using the CZT camera (P = NS).. LVEFs calculated from CZT-SPECT and CZT-repro correlated well with NaI-planar. CZT camera may reduce imaging time while preserving image quality in the assessment of biventricular EFs.

Topics: Adolescent; Adult; Aged; Cadmium Compounds; Gated Blood-Pool Imaging; Humans; Image Interpretation, Computer-Assisted; Male; Middle Aged; Radionuclide Imaging; Reproducibility of Results; Sensitivity and Specificity; Stroke Volume; Tellurium; Tomography, Emission-Computed, Single-Photon; Ventricular Dysfunction; Young Adult; Zinc

A novel dual emission ratiometric fluorescence probe for determination of glucose has been developed. The reference dye fluorescence isothiocyanate (FITC) has been encapsulated in the silica nanoparticles and then the red emission CdTe QDs were grafted on the surface of the silica particles to obtain the fluorescence probe. With glucose and dopamine as substrates, the glucose level was proportional to the fluorescence ratio change of above probe caused by dopamine oxidation, which was produced via bienzyme catalysis (glucose oxidase and horseradish peroxidase). The established approach was sensitive and selective, and has been applied to determine the glucose in beverage, urine and serum samples. The average recoveries of the glucose at various spiking levels ranged from 95.5% to 108.9% with relative standard deviations from 1.5% to 4.3%. The results provided a clue to develop sensors for rapid determination of the target analytes from complex matrices.

Topics: Beverages; Blood Glucose; Body Fluids; Cadmium Compounds; Fluorescence; Fluorescent Dyes; Glucose; Humans; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium; Urine

A dual-channel optical sensing platform which combines the advantages of dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) and fluorescence has been designed for the detection of diminazene aceturate (DA). It is based on the use of thioglycolic acid-wrapped CdTe/CdS quantum dots (Q-dots). In the absence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots exhibit the high fluorescence spectrum and low RRS spectrum, so are selected to develop an easy-to-get system. In the presence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots and DA form a complex through electrostatic interaction, which result in the RRS intensity getting enhanced significantly with new RRS peaks appearing at 317 and 397 nm; the fluorescence is powerfully quenched. Under optimum conditions, the scattering intensities of the two peaks are proportional to the concentration of DA in the range of 0.0061-3.0 μg mL(-1). The detection limits for the two single peaks are 4.1 ng mL(-1) and 3.3 ng mL(-1), while that of the DWO-RRS method is 1.8 ng mL(-1), indicating that the DWO-RRS method has high sensitivity. Besides, the fluorescence also exhibits good linear range from 0.0354 to 10.0 μg mL(-1) with a detection limit of 10.6 ng mL(-1). In addition, the system has been applied to the detection of DA in milk samples with satisfactory results.

Topics: Animals; Antiprotozoal Agents; Cadmium Compounds; Diminazene; Food Contamination; Limit of Detection; Milk; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Sulfides; Tellurium; Thioglycolates

Here we designed a near-infrared electrochemiluminescence (NECL) aptasensor for turn-on ultrasensitive determination of thrombin. It was based on the ECL resonance energy transfer (ECL-RET) of CdTe/CdS coresmall/shellthick quantum dots (QDs) to gold nanorods (AuNRs). AuNRs which functioned as ECL acceptors were assembled onto CdTe/CdS film by DNA hybridization between aptamers and their complementary oligonucleotides. In the absence of thrombin, the NECL of QDs was quenched as a result of the ECL-RET of QDs to AuNRs. In the presence of thrombin, the NECL of the system was "turned on" because thrombin can replace the AuNRs onto the QDs film, owing to the specific aptamer-protein affinity interactions. In this way, the increment of ECL intensity and the concentration of thrombin showed a logarithmic linear correlation in the range of 100 aM to 10 fM with a detection limit of 31 aM (S/N=3). Importantly, the developed aptasensor was successfully applied to thrombin sensing in real serum samples.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Gold; Humans; Infrared Rays; Limit of Detection; Luminescent Measurements; Nanotubes; Quantum Dots; Sulfides; Tellurium; Thrombin

A novel fluorescent nanosensor using molecularly imprinted silica nanospheres embedded CdTe quantum dots (CdTe@SiO2 @MIP) was developed for detection and quantification of chloramphenicol (CAP). The imprinted sensor was prepared by synthesis of molecularly imprinting polymer (MIP) on the hydrophilic CdTe quantum dots via reverse microemulsion method using small amounts of solvents. The resulting CdTe@SiO2 @MIP nanoparticles were characterized by fluorescence, UV-vis absorption and FT-IR spectroscopy and transmission electron microscopy. They preserved 48% of fluorescence quantum yield of the parent quantum dots. CAP remarkably quenched the fluorescence of prepared CdTe@SiO2 @MIP, probably via electron transfer mechanism. Under the optimal conditions, the relative fluorescence intensity of CdTe@SiO2 @MIP decreased with increasing CAP by a Stern-Volmer type equation in the concentration range of 40-500 µg L(-1). The corresponding detection limit was 5.0 µg L(-1). The intra-day and inter-day values for the precision of the proposed method were all <4%. The developed sensor had a good selectivity and was applied to determine CAP in spiked human and bovine serum and milk samples with satisfactory results.

Topics: Cadmium Compounds; Chloramphenicol; Fluorescent Dyes; Molecular Imprinting; Nanospheres; Polymers; Quantum Dots; Silicon Dioxide; Tellurium

The hybrid structures of metal organic frameworks (MOFs) and nanoparticles may offer the realization of effective photocatalytic materials due to combined benefits of the porous and molecular sieving properties of MOF matrix and the functional characteristics of encapsulated nanoparticles. In this study, cadmium telluride (CdTe) quantum dots (QD) are conjugated with a europium-MOF for the synthesis of a novel nanocomposite material with photocatalytic properties. Successful synthesis of a QD/Eu-MOF nanocomposite was characterized with various spectroscopic and microscopic techniques. This QD/Eu-MOF is found to be an effective catalyst to complete the degradation of Rhodamine 6G dye within 50 min.

Topics: Cadmium Compounds; Catalysis; Europium; Nanocomposites; Nanoparticles; Organic Chemicals; Oxidation-Reduction; Photochemistry; Quantum Dots; Rhodamines; Tellurium

A method was presented for fabricating the fluorescent nanocomposites containing CdTe quantum dots (QDs) and montmorillonite (MMT)-chitosan (CS). MMT-CS/CdTe QDs nanocomposites were prepared via a simple, versatile and robust approach combination of covalent and electrostatic assembly methods (Scheme 1). The negatively charged MMT was initially modified with positively charged CS through electrostatic assembly, followed by incorporation of CdTe-QDs into the MMT-CS nanosheets by covalent connections between the amino groups of CS and the carboxylic acid groups of thioglycollic acid (TGA). The X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and the FTIR were used to prove the QDs have intercalated into the MMT-CS matrix. The fluorescence emission spectra showed that the MMT-CS/CdTe QDs nanocomposites had the best fluorescence intensity compared with the bare CdTe QDs and CS-QDs.

Topics: Bentonite; Cadmium Compounds; Chitosan; Fluorescence; Nanostructures; Quantum Dots; Tellurium

Identification of right ventricular (RV) abnormalities is important in patients with suspected coronary artery disease (CAD). RV activity can be better visualized on myocardial single-photon emission computerized tomography (SPECT) using a higher sensitivity cadmium-zinc-telluride (CZT) detector. The aim of this study was to investigate the clinical significance of RV/left ventricular (LV) uptake ratios during exercise thallium-201 SPECT using CZT detectors.. A total of 102 patients underwent treadmill ECG-gated SPECT, coronary angiography, and echocardiography. SPECT myocardial perfusion was interpreted using a 17-segment model and a 0-4-point scale. RV/LV uptake ratios were calculated on the basis of maximum counts per pixel within the entire RV and LV walls. The relationships between RV/LV uptake ratio and gated SPECT, presence of CAD (≥50% stenosis in the left main or ≥70% in the main branches), demographics, and echocardiographic parameters were analyzed.. Stress RV/LV ratios correlated positively with the presence of left main or multivessel disease, and tricuspid regurgitation maximum pressure gradient. After multivariate regression, stress/rest RV/LV ratios correlated positively with mitral flow deceleration time, age, female sex, and use of β-blockers.. RV/LV uptake ratios on the basis of exercise myocardial perfusion SPECT imaging using CZT cameras are useful for the detection of severe CAD and could serve as an indicator of pulmonary hypertension and LV diastolic dysfunction.

Topics: Adult; Aged; Aged, 80 and over; Cadmium Compounds; Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography; Coronary Artery Disease; Equipment Design; Equipment Failure Analysis; Exercise Test; Female; Gamma Cameras; Humans; Male; Middle Aged; Radionuclide Ventriculography; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Tellurium; Thallium Radioisotopes; Ventricular Dysfunction, Right; Zinc

We demonstrate that for quantum dot (QD) based electrochemiluminescence (ECL), the commonly used co-reactant does not perform as effectively as potassium persulfate. By exploiting this small change in co-reactant, ECL intensity can be enhanced dramatically in a cathodic-based ECL system. However, TPA remains the preferential co-reactant-based system for anodic ECL. This phenomenon can be rationalised through the relative energy-level profiles of the QD to the co-reactant in conjunction with the applied potential range. This work highlights the importance of understanding the co-reactant pathway for optimising the application of ECL to bioanalytical analysis, in particular for near-infrared (NIR) QDs which can be utilised for analysis in blood. Graphical Abstract Optimising ECL Production Through Careful Selection of Co-Reactions Based on Energetics Involved.

Topics: Cadmium Compounds; Chitosan; Electrochemical Techniques; Electrodes; Luminescence; Luminescent Agents; Luminescent Measurements; Oxidation-Reduction; Potassium Compounds; Quantum Dots; Selenium; Sulfates; Sulfides; Tellurium; Zinc Compounds

The wide-ranging applications of fluorescent semiconductor quantum dots (QDs) have triggered increasing concerns about their biosafety. Most QD-related toxicity studies focus on the subcellular processes in cultured cells or global physiological effects on whole animals. However, it is unclear how QDs affect subcellular processes in living organisms, or how the subcellular disturbance contributes to the overall toxicity. Here the behavior and toxicity of QDs of three different sizes in Caenorhabditis elegans (C. elegans) are systematically investigated at both the systemic and the subcellular level. Specifically, clear size-dependent distribution and toxicity of the QDs in the digestive tract are observed. Short-term exposure of QDs leads to acute toxicity on C. elegans, yet incurring no lasting, irreversible damage. In contrast, chronic exposure of QDs severely inhibits development and shortens lifespan. Subcellular analysis reveals that endocytosis and nutrition storage are disrupted by QDs, which likely accounts for the severe deterioration in growth and longevity. This work reveals that QDs invasion disrupts key subcellular processes in living organisms, and may cause permanent damage to the tissues and organs over long-term retention. The findings provide invaluable information for safety evaluations of QD-based applications and offer new opportunities for design of novel nontoxic nanoprobes.

Topics: Animals; Cadmium Compounds; Caenorhabditis elegans; Quantum Dots; Semiconductors; Tellurium

This study compared two SPECT cameras with cadmium-zinc-telluride (CZT) detectors to a conventional Anger camera with cardiofocal collimators for the assessment of left ventricular (LV) function in a phantom and patients.. A gated dynamic cardiac phantom was used. Eighteen acquisitions were processed on each CZT camera and the conventional camera. The total number of counts within a myocardial volume of interest varied from 0.25 kcts to 1.5 Mcts. Ejection fraction was set to 33%, 45%, or 60%. Volume, LV ejection fraction (LVEF), regional wall thickening, and motion (17-segment model) were assessed. One hundred twenty patients with a low pretest likelihood of coronary artery disease and normal findings on stress perfusion SPECT were retrospectively analyzed to provide the reference limits for end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction, and regional function for each camera model.. In the phantom study, for each ejection fraction value, volume was higher for the CZT cameras than for the conventional camera, resulting in a decreased but more accurate LVEF (all P < 0.001). In clinical data, body-surface-indexed EDV and ESV (mL/m(2)) were higher for one of the CZT cameras (Discovery NM 530c) than for the other (D-SPECT) or the conventional camera (respectively, 40.5 ± 9.2, 37 ± 7.9, and 35.8 ± 6.8 for EDV [P < 0.001] and 12.5 ± 5.3, 9.4 ± 4.2, and 8.3 ± 4.4 for ESV [P < 0.001]), resulting in a significantly decreased LVEF: 70.3% ± 9.1% vs. 75.2% ± 8.1% vs. 77.8% ± 9.3%, respectively (P < 0.001).. The new CZT cameras yielded global LV function results different from those yielded by the conventional camera. LV volume was higher for the Discovery NM 530c than for the D-SPECT or the conventional camera, leading to decreased LVEF in healthy subjects. These differences should be considered in clinical practice and warrant the collection of a specific reference database.

Topics: Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Female; Gamma Cameras; Humans; Male; Middle Aged; Phantoms, Imaging; Reproducibility of Results; Sensitivity and Specificity; Stroke Volume; Tellurium; Tomography, Emission-Computed, Single-Photon; Transducers; Ventricular Dysfunction, Left; Zinc Compounds

This paper aimed to investigate the role of adenosine triphosphate-binding cassette (ABC) transporters on the efflux and the toxicity of nanoparticles in liver and kidney cells. In this study, we synthesized CdTe quantum dots (QDs) that were monodispersed and emitted green fluorescence (maximum peak at 530nm). Such QDs tended to accumulate in human hepatocellular carcinoma cells (HepG2), human kidney cells 2 (HK-2), and Madin-Darby canine kidney (MDCK) cells, and cause significant toxicity in all the three cell lines. Using specific inhibitors and inducers of P-glycoprotein (Pgp) and multidrug resistance associated proteins (Mrps), the cellular accumulation and subsequent toxicity of QDs in HepG2 and HK-2 cells were significantly affected, while only slight changes appeared in MDCK cells, corresponding well with the functional expressions of ABC transporters in cells. Moreover, treatment of QDs caused concentration- and time- dependent induction of ABC transporters in HepG2 and HK-2 cells, but such phenomenon was barely found in MDCK cells. Furthermore, the effects of CdTe QDs on ABC transporters were found to be greater than those of CdCl2 at equivalent concentrations of cadmium, indicating that the effects of QDs should be a combination of free Cd(2+) and specific properties of QDs. Overall, these results indicated a strong dependence between the functional expressions of ABC transporters and the efflux of QDs, which could be an important reason for the modulation of QDs toxicity by ABC transporters.

Topics: Animals; ATP-Binding Cassette Transporters; Cadmium Compounds; Cell Line; Cell Survival; Cyclosporine; Dogs; Hep G2 Cells; Humans; Kidney; Liver; Madin Darby Canine Kidney Cells; Oligopeptides; Probenecid; Propionates; Quantum Dots; Quinolines; Rifampin; RNA, Messenger; Tellurium

Quantum dot (QD) nanoparticles can coexist with Cu(2+) in soil and can adsorb Cu(2+) entering into bacterial cells, thereby promoting cellular copper accumulation and enhancing the combined toxicity of these two chemicals. Toxicity test results on Bacillus subtilis showed that the addition of safe concentrations of MPA-CdTe QDs to Cu(2+) culture (levels under IC50 value) resulted in higher toxicity with about twofold reduction in cell viability and increased intracellular Cu content. ROS levels also increased by about 500%, and SOD activity was altered after QD addition. Treatment with Cu(2+) alone decreased the α-amylase activity of B. subtilis by 8%-35%. This finding was not affected by QD addition. Moreover, increased cellular copper concentration as a result of QD addition enhanced toxicity primarily by producing superoxide anions. However, this phenomenon did not interrupt the physical-biological responses of soil microbes.

Topics: alpha-Amylases; Bacillus subtilis; Cadmium Compounds; Copper; Oxidative Stress; Quantum Dots; Reactive Oxygen Species; Superoxide Dismutase; Tellurium

Fluorescent quantum dots (QDs) are highly promising nanomaterials for various biological and biomedical applications because of their unique optical properties, such as robust photostability, strong photoluminescence, and size-tunable fluorescence. Several studies have reported the in vivo toxicity of QDs, but their effects on the male reproduction system have not been examined. In this study, we investigated the reproductive toxicity of cadmium telluride (CdTe) QDs at a high dose of 2.0 nmol per mouse and a low dose of 0.2 nmol per mouse. Body weight measurements demonstrated there was no overt toxicity for both dose at day 90 after exposure, but the high dose CdTe affected body weight up to 15 days after exposure. CdTe QDs accumulated in the testes and damaged the tissue structure for both doses on day 90. Meanwhile, either of two CdTe QDs treatments did not significantly affect the quantity of sperm, but the high dose CdTe significantly decreased the quality of sperm on day 60. The serum levels of three major sex hormones were also perturbed by CdTe QDs treatment. However, the pregnancy rate and delivery success of female mice that mated with the treated male mice did not differ from those mated with untreated male mice. These results suggest that CdTe QDs can cause testes toxicity in a dose-dependent manner. The low dose of CdTe QDs is relatively safe for the reproductive system of male mice. Our preliminary result enables better understanding of the reproductive toxicity induced by cadmium-containing QDs and provides insight into the safe use of these nanoparticles in biological and environmental systems.

Topics: Acrosome; Aging; Animals; Body Weight; Cadmium Compounds; DNA Fragmentation; Epididymis; Fertility; Genitalia; Hormones; Male; Mice, Inbred BALB C; Nanoparticles; Quantum Dots; Spectrophotometry, Ultraviolet; Spermatozoa; Tellurium; Testis; Tissue Distribution

High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector.. A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit.. At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54 μm square pixels using trilinear interpolation, the presampled MTF at Nyquist frequency of 9.26 cycles/mm was 0.29 and 0.24 along the orthogonal directions and the limiting resolution (10% MTF) occurred at approximately 12 cycles/mm. Visual analysis of a bar pattern image showed the ability to resolve close to 12 line-pairs/mm and qualitative evaluation of a neurovascular nitinol-stent showed the ability to visualize its struts at clinically relevant conditions.. Hexagonal pixel array photon-counting CdTe detector provides high spatial resolution in single-photon counting mode. After resampling to optimal square pixel size for distortion-free display, the spatial resolution is preserved. The dual-energy capabilities of the detector could allow for artifact-free subtraction angiography and basis material decomposition. The proposed high-resolution photon-counting detector with energy-resolving capability can be of importance for several image-guided interventional procedures as well as for pediatric applications.

Topics: Alloys; Angiography, Digital Subtraction; Blood Vessels; Cadmium Compounds; Fingers; Humans; Linear Models; Models, Anatomic; Phantoms, Imaging; Photons; Polymethyl Methacrylate; Radiometry; Stents; Tellurium; Therapy, Computer-Assisted; Wrist; X-Rays

Herein, a novel signal amplification strategy was designed using the perylene derivative as the co-reaction accelerator toward graphene-CdTe quantum dots (G-CdTe)/S2O8(2-) system to construct a highly sensitive electrochemiluminescent (ECL) aptasensor for thrombin (TB) detection. Firstly, the G-CdTe nanocomposites were prepared by one-step method of in situ generating CdTe quantum dots onto the surface of the graphene oxide by using 3-mercaptopropionic acid as the CdTe QDs stabilizer. Then, a kind of perylene derivative (PTC-Lys), was synthesized by covalently binding L-lysine to 3,4,9,10-perylenetetracarboxylic acid, which was further immobilized onto the G-CdTe by the π-π* stacking and cross-linked the detection thrombin aptamer (TBA II) to obtain the TBA II/PTC-Lys/G-CdTe signal probes. It is worth pointing out that PTC-Lys acting as an efficient co-reaction accelerator interacted with the co-reactant of S2O8(2-) rather than G-CdTe to promote the more oxidant mediators of SO4(•-), which could further react with G-CdTe to produce excited state species G-CdTe* for emitting light. Compared with the G-CdTe/S2O8(2-) ECL system, our proposed strategy with the introduction of co-reaction accelerator of PTC-Lys exhibited ultra-high sensitivity to quantify the concentration of TB from 1.0×10(-7)nM to 10nM with a detection limit of 34aM.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Graphite; Humans; Limit of Detection; Luminescent Measurements; Nanocomposites; Perylene; Quantum Dots; Tellurium; Thrombin

Fluorescent nanoparticles or quantum dots (QDs) have been intensely studied for basic and applied research due to their unique size-dependent properties. There is an increasing interest in developing ecofriendly methods to synthesize these nanoparticles since they improve biocompatibility and avoid the generation of toxic byproducts. The use of biological systems, particularly prokaryotes, has emerged as a promising alternative. Recent studies indicate that QDs biosynthesis is related to factors such as cellular redox status and antioxidant defenses. Based on this, the mixture of extreme conditions of Antarctica would allow the development of natural QDs producing bacteria.. In this study we isolated and characterized cadmium and tellurite resistant Antarctic bacteria capable of synthesizing CdS and CdTe QDs when exposed to these oxidizing heavy metals. A time dependent change in fluorescence emission color, moving from green to red, was determined on bacterial cells exposed to metals. Biosynthesis was observed in cells grown at different temperatures and high metal concentrations. Electron microscopy analysis of treated cells revealed nanometric electron-dense elements and structures resembling membrane vesicles mostly associated to periplasmic space. Purified biosynthesized QDs displayed broad absorption and emission spectra characteristic of biogenic Cd nanoparticles.. Our work presents a novel and simple biological approach to produce QDs at room temperature by using heavy metal resistant Antarctic bacteria, highlighting the unique properties of these microorganisms as potent natural producers of nano-scale materials and promising candidates for bioremediation purposes.

Topics: Antarctic Regions; Bacteria; Cadmium Compounds; Drug Resistance, Bacterial; Fluorescent Dyes; Metabolome; Metals, Heavy; Microscopy, Electron, Transmission; Nanoparticles; Quantum Dots; RNA, Ribosomal, 16S; Spectrometry, Fluorescence; Sulfides; Tellurium

Within the SYRMA-CT collaboration based at the ELETTRA synchrotron radiation (SR) facility the authors investigated the imaging performance of the phase-contrast computed tomography (CT) system dedicated to monochromatic in vivo 3D imaging of the female breast, for breast cancer diagnosis.. Test objects were imaged at 38keV using monochromatic SR and a high-resolution CdTe photon-counting detector. Signal and noise performance were evaluated using modulation transfer function (MTF) and noise power spectrum. The analysis was performed on the images obtained with the application of a phase retrieval algorithm as well as on those obtained without phase retrieval. The contrast to noise ratio (CNR) and the capability of detecting test microcalcification clusters and soft masses were investigated.. For a voxel size of (60μm)(3), images without phase retrieval showed higher spatial resolution (6.7mm(-1) at 10% MTF) than corresponding images with phase retrieval (2.5mm(-1)). Phase retrieval produced a reduction of the noise level and an increase of the CNR by more than one order of magnitude, compared to raw phase-contrast images. Microcalcifications with a diameter down to 130μm could be detected in both types of images.. The investigation on test objects indicates that breast CT with a monochromatic SR source is technically feasible in terms of spatial resolution, image noise and contrast, for in vivo 3D imaging with a dose comparable to that of two-view mammography. Images obtained with the phase retrieval algorithm showed the best performance in the trade-off between spatial resolution and image noise.

Topics: Algorithms; Breast; Breast Neoplasms; Cadmium Compounds; Calcinosis; Contrast Media; Equipment Design; Female; Humans; Mammography; Microscopy, Phase-Contrast; Photons; Radiation Dosage; Radiographic Image Interpretation, Computer-Assisted; Signal-To-Noise Ratio; Synchrotrons; Tellurium; Tomography, X-Ray Computed

Monitoring of bio-catalytic events by using nano-probes is of immense interest due to unique optical properties of metal nanoparticles. In the present study, tunneling of enzyme activity was achieved using redox cofactors namely oxidized cytochrome-c (Cyt-c) and Co-enzyme-Q (Co-Q) immobilized on Quantum dots (QDs) which acted as a bio-probe for NAD(+) dependent dehydrogenase catalyzed reaction. We studied how electron transfer from substrate to non-native electron acceptors can differentially modify photoluminescence properties of CdTe QDs. Two probes were designed, QD-Ox-Cyt-c and QD-Ox-Co-Q, which were found to quench the fluorescence of QDs. However, formaldehyde dehydrogenase (FDH) catalyzed reduction of Cyt-c and Co-Q on the surface of QDs lead to fluorescence turn-on of CdTe QDs. This phenomenon was successfully used for the detection of HCHO in the range of 0.01-100,000ng/mL (LOD of 0.01ng/mL) using both QD-Ox-Cyt-c (R(2)=0.93) and QD-Ox-Co-Q (R(2)=0.96). Further probe performance and stability in samples like milk, wine and fruit juice matrix were studied and we could detect HCHO in range of 0.001-100,000ng/mL (LOD of 0.001ng/mL) with good stability and sensitivity of probe in real samples (R(2)=0.97). Appreciable recovery and detection sensitivity in the presence of metal ions suggests that the developed nano-probes can be used successfully for monitoring dehydrogenase based bio-catalytic events even in the absence of NAD(+). Proposed method is advantageous over classical methods as clean up/ derivatization of samples is not required for formaldehyde detection.

Topics: Aldehyde Oxidoreductases; Animals; Biosensing Techniques; Cadmium Compounds; Cytochromes c; Electron Transport; Enzymes, Immobilized; Food Analysis; Formaldehyde; Fruit and Vegetable Juices; Milk; NAD; Oxidation-Reduction; Quantum Dots; Tellurium; Ubiquinone; Wine

A one step, rapid method to prepare silk microspheres was developed, with particle size controlled by the addition of polyethylene glycol (PEG). PEG molecular weight (4.0K-20.0KDa) and concentration (20-50wt%), as well as silk concentration (5-20wt%), were key factors that determined particle sizes varying in a range of 1-100μm. Addition of methanol to the PEG-silk combinations increased the content of crystalline β-sheet in the silk microspheres. To track the distribution and degradation of silk microspheres in vivo, 3-mercaptopropionic acid (MPA)-coated CdTe quantum dots (QDs) were physically entrapped in the silk microspheres. QDs tightly bound to the β-sheet domains of silk via hydrophobic interactions, with over 96% of the loaded QDs remaining in the silk microspheres after exhaustive extraction. The fluorescence of QDs-incorporated silk microspheres less stable in cell culture medium than in phosphate buffer solution (PBS) and water. After subcutaneous injection in mice, microspheres prepared from 20% silk (approx. 30μm diameter particles) still fluoresced at 24h, while those prepared from 8% silk (approx. 4μm diameter particles) and free QDs were not detectable, reflecting the QDs quenching and particle size effect on microsphere clearance in vivo. The larger microspheres were more resistant to cell internalization and degradation. Since PEG is an FDA-approved polymer, and silk is FDA approved for some medical devices, the methods developed in the present study will be useful in a variety of biomedical applications where simple, rapid and scalable preparation of silk microspheres is required.. The work is of significance to the biomaterial and controlled release society because it provides a new option for fabricating silk microspheres in one simple step of mixing silk and polyethylene glycol (PEG), with the size and properties of microspheres controllable by PEG molecular weight as well as PEG and silk concentrations. Although fabrication of silk microspheres have been reported previously using spray-drying, liposome-templating, polyvinyl alcohol (PVA) emulsification, etc., applications were hindered due to harsh conditions (temperature, solvents, etc.) and complicated procedures used as well as low yield and less controllable particle size (usually <10μm). Since PEG is an FDA-approved polymer, and silk is FDA approved for some medical devices, the methods developed in the present study will be useful in a variety of biomedical applications where simple, rapid and scalable preparation of silk microspheres is required.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Methanol; Mice; Microspheres; Polyethylene Glycols; Quantum Dots; Silk; Tellurium

A facile one-pot strategy has been developed for the aqueous synthesis of Gd doped CdTe (Gd:CdTe) QDs as fluorescence and magnetic resonance imaging dual-modal agent. The prepared Gd:CdTe QDs showed narrow size distribution and the average size was less than 5nm. The amount of Gd(3+) dopant in Gd:CdTe QDs significantly affected the optical properties of obtained QDs. The highest PL QY for the prepared Gd:CdTe QDs was up to 42.5%. The QDs showed the weak toxicity and significant enhancement in MRI signal. The specific relaxivity value (r1) was determined to be 4.22mM(-1)s(-1). These properties make the prepared Gd:CdTe QDs be an effective dual-modal imaging agent and have great potential applications in biomedical field.

Topics: Caco-2 Cells; Cadmium Compounds; Chemistry Techniques, Synthetic; Gadolinium; Humans; Magnetic Resonance Imaging; Optical Imaging; Quantum Dots; Tellurium; Water

Beta-amyloid (Aβ) peptides are the major constituents of senile plaques in the brains of Alzheimer's disease (AD) patients. Aβ monomers (AβMs) can coalesce to form small, soluble oligomers (AβOs), followed by reorganization and assembly into long, thread-like fibrils (AβFs). Recently, soluble AβOs have been regarded as reliable molecular biomarkers for the diagnosis of AD because of their high toxicity for neuronal synapse and high concentration levels in the brains of AD patients. In this work, we reported a label-free, sensitive and selective method for visual and fluorescent detection of AβOs based on the inner filter effect (IFE) of gold nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs). Specifically, the fluorescence of CdTe QDs was quenched significantly by AuNPs through the IFE. PrP(95-110), an AβOs-specific binding peptide from cellular prion protein, triggered the aggregation and color change of AuNPs suspension; thus, the IFE of AuNPs on the fluorescence of CdTe QDs was weakened and the fluorescence intensity was recovered. However, in the presence of AβOs, the specific interaction of AβOs and PrP(95-110) prevented the absorption of PrP(95-110) onto the surface of AuNPs. As a result, the aggregation of AuNPs was inhibited and the fluorescence intensity of CdTe QDs was quenched again. This label-free method is specific for detection of AβOs but not for AβMs and AβFs. The detection limits were found to be 0.5nM for the visual assay and 0.2nM for the fluorescent detection. We believe that this work would be valuable for many investigations related to AD diagnosis and drug discovery.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Biosensing Techniques; Cadmium Compounds; Fluorescence; Fluorescent Dyes; Gold; Humans; Limit of Detection; Metal Nanoparticles; Peptide Fragments; Quantum Dots; Solubility; Spectrometry, Fluorescence; Tellurium

This work carries out for the first time the comparison between the physical and chemical immobilization of choline oxidase onto aminated silica-based porous supports. The influence on the immobilization efficiency of concentration, pH, temperature and contact time between the support and choline oxidase, was evaluated. The immobilization efficiency was estimated taking into consideration the choline oxidase activity, which was assessed by using cadmium telluride (CdTe) quantum dots (QDs), obtained by hydrothermal synthesis, as photoluminescent probes. Hydrogen peroxide produced by enzyme activity was capable of quenching CdTe QDs photoluminescence. The magnitude of the PL quenching process was directly related with the enzyme activity. By comparing the chemical process with the physical adsorption, it was observed that the latter provided the highest choline oxidase immobilization. The equilibrium data were analyzed using Langmuir and Freundlich isotherms and kinetic data were fitted to the pseudo-first-order and pseudo-second-order models. Thermodynamic parameters, such as Gibbs free energy and entropy were also calculated. These results will certainly contribute to the development of new sensing schemes for choline, taking into account the growing demand for its quantification in biological samples.

Topics: Adsorption; Alcohol Oxidoreductases; Biosensing Techniques; Cadmium Compounds; Choline; Enzyme Stability; Enzymes, Immobilized; Kinetics; Porosity; Quantum Dots; Silicon Dioxide; Tellurium; Thermodynamics

The photo-induced interaction of three different sizes of thioglycolic acid (TGA)-capped CdTe quantum dots (CdTe QDs) with two monomethine cyanine dyes belonging to the thiazole orange (TO) family has been studied. Positively charged cyanines interact with QDs surface which is negatively charged due to capping agent carboxylate ions. The energy transfer parameters including Stern-Volmer constant, Ksv, number of binding sites, n, quenching sphere radius, r, the critical energy transfer distance, R0, and energy transfer efficiencies, E have been calculated. The effect of structure and the number of aggregating molecules have been studied as a function of CdTe QDs particle size. Combining organic and inorganic semiconductors leads to increase of the effective absorption cross section of the QDs which can be utilized in novel nanoscale designs for light-emitting, photovoltaic and sensor applications. A synthesized triplet emission of the studied dyes was observed using CdTe QDs as donors and this is expected to play a potential role in molecular oxygen sensitization and in photodynamic therapy (PDT) applications.

Topics: Cadmium Compounds; Carbocyanines; Coloring Agents; Energy Transfer; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thermodynamics; Thioglycolates

A complete understanding of the toxicological behavior of quantum dots (QDs) in vivo is of great importance and a prerequisite for their application in humans. In contrast with the numerous cytotoxicity studies investigating QDs, only a few in vivo studies of QDs have been reported, and the issue remains controversial. Our study aimed to understand QD-mediated toxicity across different time points and to explore the roles of free cadmium ions (Cd(2+)) and hydroxyl radicals (·OH) in tissue damage. Male ICR mice were administered a single intravenous dose (1.5 µmol/kg) of CdTe QDs, and liver and kidney function and morphology were subsequently examined at 1, 7, 14, and 28 days. Furthermore, ·OH production in the tissue was quantified by trapping · OH with salicylic acid (SA) as 2,3-dihydroxybenzoic acid (DHBA) and detecting it using a high-performance liquid chromatography fluorescence method. We used the induction of tissue metallothionein levels and 2,3-DHBA:SA ratios as markers for elevated Cd(2+) from the degradation of QDs and ·OH generation in the tissue, respectively. Our experimental results revealed that the QD-induced histopathological changes were time-dependent with elevated Cd(2+) and ·OH, and could recover after a period of time. The Cd(2+) and ·OH exhibited delayed effects in terms of histopathological abnormalities. Histological assessments performed at multiple time points might facilitate the evaluation of the biological safety of QDs.

Topics: Animals; Cadmium; Cadmium Compounds; Chromatography, High Pressure Liquid; Humans; Hydroxyl Radical; Immunohistochemistry; Ions; Kidney; Liver; Male; Metallothionein; Mice, Inbred ICR; Quantum Dots; Tellurium; Time Factors

A direct competitive fluorescent enzyme-linked immunosorbent assay (ELISA) was developed for the detection of zearalenone (ZEN) using ZEN labeled catalase (CAT) as a competing antigen with H2O2-sensitive CdTe quantum dots (QDs) for signal transduction. The novel fluorescent ELISA showed very high sensitivity for ZEN detection because it combined the high catalytic activity of CAT to H2O2 and H2O2-sensitive property of QDs. Under optimal conditions, the developed method showed a good dynamic linear detection for ZEN in the range of 2.4pg/mL to 1.25ng/mL with a detection limit of 4.1pg/mL. The median inhibition concentration (IC50) of ZEN was 75pg/mL, which was approximately 17-fold lower than that of horseradish peroxidase-based conventional ELISA. Moreover, our developed method also showed a high reproducibility and an excellent selectivity. In brief, the novel fluorescent ELISA shows great potential for the sensitive and economic detection of mycotoxins and other analytes in food analysis, clinical diagnosis and environmental monitoring.

Topics: Antibodies, Monoclonal; Antigens; Cadmium Compounds; Catalase; Enzyme-Linked Immunosorbent Assay; Fluorescence; Food Contamination; Hydrogen Peroxide; Quantum Dots; Signal Transduction; Tellurium; Zea mays; Zearalenone

Mycotoxins, highly toxic secondary metabolites produced by many invading species of filamentous fungi, contaminate different agricultural commodities under favorable temperature and humidity conditions. Herein, we successfully devised a novel signal-on photoelectrochemical immunosensing platform for the quantitative monitoring of mycotoxins (aflatoxin B1, AFB1, used as a model) in foodstuffs on the basis of silver nanolabels-assisted ion-exchange reaction with CdTe quantum dots (QDs) mediated hole-trapping. Initially, a competitive-type immunoreaction was carried out on a high-binding microplate by using silver nanoparticle (AgNP)-labeled AFB1-bovine serum albumin (AFB1-BSA) conjugates as the tags. Then, the carried AgNPs with AFB1-BSA were dissolved by acid to release numerous silver ions, which could induce ion-exchange reaction with the CdTe QDs immobilized on the electrode, thus resulting in formation of surface exciton trapping. Relative to pure CdTe QDs, the formed exciton trapping decreased the photocurrent of the modified electrode. In contrast, the detectable photocurrent increased with the increase of target AFB1 in a dynamic working range from 10 pg mL(-1) to 15 ng mL(-1) at a low limit of detection (LOD) of 3.0 pg mL(-1) under optimal conditions. In addition, the as-prepared photoelectrochemical immunosensing platform also displayed high specificity, good reproducibility, and acceptable method accuracy for detecting naturally contaminated/spiked blank peanut samples with consistent results obtained from the referenced enzyme-linked immunosorbent assay (ELISA) method.

Topics: Aflatoxin B1; Animals; Cadmium Compounds; Cattle; Electrochemical Techniques; Electrodes; Immunoassay; Light; Limit of Detection; Metal Nanoparticles; Mycotoxins; Quantum Dots; Serum Albumin; Serum Albumin, Bovine; Silver; Tellurium

With the rapid development of nanotechnology, quantum dots (QDs) as advanced nanotechnology products have been widely used in neuroscience, including basic neurological studies and diagnosis or therapy for neurological disorders, due to their superior optical properties. In recent years, there has been intense concern regarding the toxicity of QDs, with a growing number of studies. However, knowledge of neurotoxic consequences of QDs applied in living organisms is lagging behind their development, even if several studies have attempted to evaluate the toxicity of QDs on neural cells. The aim of this study was to evaluate the adverse effects of intrahippocampal injection in rats of 3-mercaptopropionic acid (MPA)-modified CdTe QDs and underlying mechanisms. First of all, we observed impairments in learning efficiency and spatial memory in the MPA-modified CdTe QD-treated rats by using open-field and Y-maze tests, which could be attributed to pathological changes and disruption of ultrastructure of neurons and synapses in the hippocampus. In order to find the mechanisms causing these effects, transcriptome sequencing (RNA-seq), an advanced technology, was used to gain the potentially molecular targets of MPA-modified CdTe QDs. According to ample data from RNA-seq, we chose the signaling pathways of PI3K-Akt and MPAK-ERK to do a thorough investigation, because they play important roles in synaptic plasticity, long-term potentiation, and spatial memory. The data demonstrated that phosphorylated Akt (p-Akt), p-ERK1/2, and c-FOS signal transductions in the hippocampus of rats were involved in the mechanism underlying spatial learning and memory impairments caused by 3.5 nm MPA-modified CdTe QDs.

Topics: 3-Mercaptopropionic Acid; Animals; Behavior, Animal; Cadmium Compounds; Gene Expression; Hippocampus; Injections; Long-Term Potentiation; Male; Memory; Neuronal Plasticity; Neurons; Phosphatidylinositol 3-Kinases; Quantum Dots; Rats, Wistar; Signal Transduction; Spatial Learning; Tellurium

Due to the low titer or uneven distribution of Citrus tristeza virus (CTV) in field samples, detection of CTV by using conventional detection techniques may be difficult. Therefore, in the present work, the cadmium-telluride quantum dots (QDs) was conjugated with a specific antibody against coat protein (CP) of CTV, and the CP were immobilized on the surface of gold nanoparticles (AuNPs) to develop a specific and sensitive fluorescence resonance energy transfer (FRET)-based nanobiosensor for detecting CTV. The maximum FRET efficiency for the developed nano-biosensor was observed at 60% in AuNPs-CP/QDs-Ab ratio of 1:8.5. The designed system showed higher sensitivity and specificity over enzyme linked immunosorbent assay (ELISA) with a limit of detection of 0.13μgmL(-1) and 93% and 94% sensitivity and specificity, respectively. As designed sensor is rapid, sensitive, specific and efficient in detecting CTV, this could be envisioned for diagnostic applications, surveillance and plant certification program.

Topics: Antibodies, Immobilized; Biosensing Techniques; Cadmium Compounds; Citrus; Closterovirus; Fluorescence Resonance Energy Transfer; Gold; Limit of Detection; Metal Nanoparticles; Plant Diseases; Quantum Dots; Tellurium

The present study reports the localization and interaction of thioglycolic acid (TGA) capped CdTe quantum dots (TGA@CdTe QDs) within the extracellular matrix (ECM) of Haematococcus pluvialis (Chlorophyceae) microalgae (HPM) after an incubation period of 5 min. Changes in the Raman spectrum of HPM induced by the adsorption of the TGA@CdTe QDs are successfully found by using naked gold anisotropic structures as nano-sensors for surface-enhanced Raman scattering (SERS effect). Raman spectroscopy results show that TGA@CdTe QDs interact with the biomolecules present in the ECM. Sample preparation and characterization by complementary techniques such as confocal and electron microscopy are also used to confirm the presence and localization of the nanoparticles in the algae. This research shows new evidence on early accumulation of QDs in plant cells and would further improve our understanding about their environmental impact.

Topics: Cadmium Compounds; Extracellular Matrix; Gold; Metal Nanoparticles; Microalgae; Quantum Dots; Spectrum Analysis, Raman; Tellurium; Thioglycolates; Volvocida

CdSe/CdS/ZnS and CdTe quantum dots (QDs) were synthesized by successive ion layer adsorption and reaction (SILAR) technique and direct aqueous synthesis respectively using thiol stabilizers. Synthesized CdSe/CdS/ZnS and CdTe QDs stabilized with 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) were used as fluorescent labels after conjugation with folic acid (FA) and anti-HER2 antibodies. Photoluminescence quantum yield of folated CdSe/CdS/ZnS-MPA and CdTe-MSA QDs was 59% and 77% than that of non-folated hydrophilic QDs. The folate receptor-mediated delivery of folic acid-conjugated CdTe-MSA and CdSe/CdS/ZnS-MPA QDs showed higher cellular internalization as observed by confocal laser scanning microscopic studies. Folated and non-folated CdTe-MSA QDs were highly toxic and exhibited only 10% cell viability as compared to > 80% cell viability with CdSe/CdS/ZnS-MPA QDs over the concentration ranging from 3.38 to 50 pmoles. Immunohistochemistry (IHC) results of human breast cancer tissue samples showed positive results with anti-HER2 antibody conjugated CdSe/CdS/ZnS-MPA QDs with better sensitivity and specificity as compared to conventional IHC analysis using diaminobenzedene staining.

Topics: 3-Mercaptopropionic Acid; Animals; Antibodies, Neoplasm; Breast Neoplasms; Cadmium Compounds; Drug Delivery Systems; Female; Folic Acid; Humans; Mice; Mice, Inbred BALB C; Quantum Dots; Receptor, ErbB-2; Selenium Compounds; Succinates; Sulfides; Tellurium; Zinc Compounds

Currently, DNA nanotechnology offers the most programmable, scalable, and accurate route for the self-assembly of matter with nanometer precision into 1, 2, or 3D structures. One example is DNA origami that is well suited to serve as a molecularly defined "breadboard", and thus, to organize various nanomaterials such as nanoparticles into hybrid systems. Since the controlled assembly of quantum dots (QDs) is of high interest in the field of photonics and other optoelectronic applications, a more detailed view on the functionalization of QDs with oligonucleotides shall be achieved. In this work, four different methods are presented to characterize the functionalization of thiol-capped cadmium telluride QDs with oligonucleotides and for the precise quantification of the number of oligonucleotides bound to the QD surface. This study enables applications requiring the self-assembly of semiconductor-oligonucleotide hybrid materials and proves the conjugation success in a simple and straightforward manner.

Topics: Cadmium Compounds; DNA; Edetic Acid; Fluorescent Dyes; Luminescence; Nanotechnology; Oligonucleotides; Quantum Dots; Spectrum Analysis; Tellurium

Fluorescent test papers are promising for the wide applications in the assays of diagnosis, environments and foods, but unlike classical dye-absorption-based pH test paper, they are usually limited in the qualitative yes/no type of detection by fluorescent brightness, and the colorimetry-based quantification remains a challenging task. Here, we report a single dual-emissive nanofluorophore probe to achieve the consecutive color variations from blue to red for the quantification of blood glucose on its as-prepared test papers. Red quantum dots were embedded into silica nanoparticles as a stable internal standard emission, and blue carbon dots (CDs) were further covalently linked onto the surface of silica, in which the ratiometric fluorescence intensity of blue to red is controlled at 5:1. While the oxidation of glucose induced the formation of Fe(3+) ions, the blue emission of CDs was thus quenched by the electron transfer from CDs to Fe(3+), displaying a serial of consecutive color variations from blue to red with the dosage of glucose. The high-quality test papers printed by the probe ink exhibited a dosage-sensitive allochromatic capability with the clear differentiations of ~5, 7, 9, 11mM glucose in human serum (normal: 3-8mM). The blood glucose determined by the test paper was almost in accordance with that measured by a standard glucometer. The method reported here opens a window to the wide applications of fluorescent test paper in biological assays.

Topics: Biosensing Techniques; Blood Glucose; Cadmium Compounds; Colorimetry; Fluorescent Dyes; Humans; Limit of Detection; Paper; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

A facile and efficient one-pot approach for the synthesis of quantum dot (QD)-labeled hydrophilic molecularly imprinted polymer (MIP) nanoparticles for direct optosensing of folic acid (FA) in the undiluted bovine and porcine serums is described. Hydrophilic macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization was used to implement the molecular imprinting of FA in the presence of CdTe quantum dots (QDs). The resulting FA-imprinted polymer nanoparticles with surface-grafted hydrophilic poly(glyceryl monomethacrylate) brushes and QDs labeling not only showed outstanding specific molecular recognition toward FA in biological samples, but also exhibited good photostability, rapid binding kinetics, and obvious template binding-induced fluorescence quenching. These characteristics make them a useful fluorescent chemosensor for directly and selectively optosensing FA in the undiluted bovine and porcine serums, with its limit of detection being 0.025μM and average recoveries ranging from 98% to 102%, even in the presence of several interfering compounds. This advanced fluorescent MIP chemosensor is highly promising for rapid quantification of FA in such applications as clinical diagnostics and food analysis.

Topics: Animals; Blood Chemical Analysis; Cadmium Compounds; Cattle; Folic Acid; Hydrophobic and Hydrophilic Interactions; Molecular Imaging; Molecular Imprinting; Polymers; Quantum Dots; Spectrometry, Fluorescence; Staining and Labeling; Swine; Tellurium

Wogonin (5,7-dihydroxy-8-methoxyflavone) is one of the active components of flavonoids isolated from Scutellariae radix and possesses antitumor effect against leukemia. Cadmium-telluride quantum dots (CdTe-QDs) are a kind of nanoparticles with great potential in functioning as an efficient drug delivery vector in biomedical research. In this study, we investigated the synergistic effect of CdTe-QDs with Wogonin on the induction of apoptosis using drug-resistant human leukemia KA cells. Flow cytometry analysis, assay of morphology under electron microscope, quantitative analysis of tumor volume and micro-CT imaging demonstrated that compared with that by pure CdTe-QDs or wogonin, the apoptosis rate increased sharply when treated wirh CdTe-QDs together with wogonin on KA cells. These results proved that the nanocomposites readily overcame the barrier of drug-resistance and provoked cell apoptosis in vitro and in vivo by facilitating the interaction between wogonin and KA cells. As known to all, it is an inevitable tendency that new effective therapies will take the place of conventional chemotherapy and radiotherapy presenting significant disadvantages. According to this article, CdTe-QD combined with wogonin is a possible alternative for some cancer treatments.

Topics: Animals; Apoptosis; Cadmium Compounds; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Flavanones; Heterografts; Humans; K562 Cells; Leukemia, Erythroblastic, Acute; Mice; Mice, Nude; Microscopy, Electron, Transmission; Quantum Dots; Tellurium; X-Ray Microtomography

We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.

Topics: Cadmium Compounds; Colloids; Hydrodynamics; Particle Size; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium; Ultracentrifugation

This work proposes the first photoelectrochemical proximity assay (PECPA) method via the sensitization of CdTe quantum dots (QDs) on photoelectrochemical response of ITO/TiO2/CdS electrode for highly selective and sensitive detection of proteins. This detection was performed on a sensing interface formed via the hybridization of capture DNA immobilized on ITO/TiO2/CdS electrode with labeled antibody-DNA (DNA-Ab1). Upon the recognition of Ab1 to target protein, the immunocomplex of DNA-Ab1, target, and the detection antibody-DNA (DNA-Ab2) was formed, which led to the proximity hybridization of the DNA in DNA-Ab2, capture DNA, and signal DNA-CdTe QDs, and brought CdTe QDs to the ITO/TiO2/CdS electrode to produce a sensitized photocurrent. The photocurrent intensity increased with the increasing concentration of the specific target protein. Using insulin as a target, this sensitized method showed a detectable range of 10 fM to 10 nM and a detection limit of 3.0 fM without the need of a washing step. It possessed high selectivity and good accuracy for detection of proteins in biological matrixes. This method is extremely flexible and can be extended to varieties of protein targets.

Topics: Antibodies; Cadmium Compounds; Electrochemical Techniques; Electrodes; Immobilized Nucleic Acids; Immunoassay; Insulin; Limit of Detection; Nucleic Acid Hybridization; Quantum Dots; Tellurium; Tin Compounds; Titanium

This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity.

Topics: Aliivibrio fischeri; Cadmium Compounds; Environmental Pollutants; Industrial Waste; Inhibitory Concentration 50; Ions; Selenium Compounds; Semiconductors; Solubility; Tellurium; Toxicity Tests

Cadmium telluride quantum dots (CdTe QDs) are used as near-infrared probes in biologic and medical applications, but their cytological effects and mechanism of potential toxicity are still unclear. In this study, we evaluated the toxicity of CdTe QDs of different sizes and investigated their mechanism of toxicity in the yeast Saccharomyces cerevisiae. A growth inhibition assay revealed that orange-emitting CdTe (O-CdTe) QDs (half inhibitory concentration [IC50] =59.44±12.02 nmol/L) were more toxic than green-emitting CdTe QDs (IC50 =186.61±19.74 nmol/L) to S. cerevisiae. Further studies on toxicity mechanisms using a transmission electron microscope and green fluorescent protein tagged Atg8 processing assay revealed that O-CdTe QDs could partially inhibit autophagy at a late stage, which differs from the results reported in mammalian cells. Moreover, autophagy inhibited at a late stage by O-CdTe QDs could be partially recovered by enhancing autophagy with rapamycin (an autophagy activator), combined with an increased number of living cells. These results indicate that inhibition of autophagy acts as a toxicity mechanism of CdTe QDs in S. cerevisiae. This work reports a novel toxicity mechanism of CdTe QDs in yeast and provides valuable information on the effect of CdTe QDs on the processes of living cells.

Topics: Animals; Autophagy; Cadmium Compounds; Green Fluorescent Proteins; Quantum Dots; Saccharomyces cerevisiae; Sirolimus; Tellurium; Vacuoles

The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H2O2) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H2O2 or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL(-1) to 625 pg mL(-1) with a limit of detection of 2.2 pg mL(-1), which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules.

Topics: Cadmium Compounds; Enzyme-Linked Immunosorbent Assay; Fluorescence; Glucose Oxidase; Hydrogen-Ion Concentration; Ochratoxins; Quantum Dots; Tellurium

In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential for uptake of the heavy QDs. Meantime, the NCs exhibited concentration-dependent adverse effects on morphology, viability, kinetic characteristics and DNA of the spermatozoa. At low concentration of 0.1μg/mL, the NCs showed a moderate toxicity (~25% reduction in viability and motility of the spermatozoa), while remarkable toxicities were observed at higher concentrations of 1.0-100μg/mL (~67% reduction in viability and motility for 100μg/mL). Furthermore, significant in vitro DNA fragmentation of the spermatozoa was observed at CdTe concentrations ≥10μg/mL. In vivo toxicity of the NCs was found lower than the in vitro toxicity. Nevertheless, the in vivo destructive effects of the NCs still caused ~34% reduction in viability as well as motility and ~5% damages in DNA of male mice spermatozoa. These resulted in ~26% decrease in fertility and gestation of female mice, along with an overall hormone secretion during the pregnancy, and ~39% reduction in viability of pups/pregnant females.

Topics: Animals; Cadmium Compounds; DNA; DNA Fragmentation; Enzyme-Linked Immunosorbent Assay; Female; Fertility; Follicle Stimulating Hormone; Luteinizing Hormone; Male; Mice; Mice, Inbred BALB C; Microscopy, Confocal; Microscopy, Electron, Transmission; Particle Size; Pregnancy; Prolactin; Quantum Dots; Reactive Oxygen Species; Spermatozoa; Tellurium

A "signal off" voltammetric aptasensor was developed for the sensitive and selective detection of ultra-low levels of adenosine triphosphate (ATP). For this purpose, a new strategy based on the principle of recognition-induced switching of aptamers from DNA/DNA duplex to DNA/target complex was designed using thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) as the signal amplifying nano-platforms. Owing to the small size, high surface-to-volume ratio and good conductivity, quantum dots were immobilized on the electrode surface for signal amplification. In this work, methylene blue (MB) adsorbed to DNA was used as a sensitive redox reporter. The intensity of voltammetric signal of MB was found to decrease linearly upon ATP addition over a concentration range of 0.1nM to 1.6μM with a correlation coefficient of 0.9924. Under optimized conditions, the aptasensor was able to selectively detect ATP with a limit of detection of 45pM at 3σ. The results also demonstrated that the QDs-based amplification strategy could be feasible for ATP assay and presented a potential universal method for other small biomolecular aptasensors.

Topics: Adenosine Triphosphate; Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; Electrochemistry; Electrodes; Methylene Blue; Nanoparticles; Quantum Dots; Solubility; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates; Water

Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three-micron thick thin-film CdTe photodetectors were fabricated in our lab. One-, ten- or one hundred-micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high-dose-rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5μm from the interface were 42.6 ± 10.8 , 137.0 ± 11.9, and 203.0 ± 15.4, respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1, and 249 ± 1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold-tissue interface was successfully measured using an in-house-built, high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.

Topics: Algorithms; Cadmium Compounds; Gold; Humans; Iridium Radioisotopes; Monte Carlo Method; Phantoms, Imaging; Radiometry; Radiotherapy Dosage; Tellurium; Water

There is increasing evidence that certain nanoparticles (NPs) can overcome the placental barrier, raising concerns on potential adverse effects on the growing fetus. But even in the absence of placental transfer, NPs may pose a risk to proper fetal development if they interfere with the viability and functionality of the placental tissue. The effects of NPs on the human placenta are not well studied or understood, and predictive in vitro placenta models to achieve mechanistic insights on NP-placenta interactions are essentially lacking. Using the scaffold-free hanging drop technology, we developed a well-organized and highly reproducible 3D co-culture microtissue (MT) model consisting of a core of placental fibroblasts surrounded by a trophoblast cell layer, which resembles the structure of the in vivo placental tissue. We could show that secretion levels of human chorionic gonadotropin (hCG) were significantly higher in 3D than in 2D cell cultures, which indicates an enhanced differentiation of trophoblasts grown on 3D MTs. NP toxicity assessment revealed that cadmium telluride (CdTe) and copper oxide (CuO) NPs but not titanium dioxide (TiO

Topics: Cadmium Compounds; Chorionic Gonadotropin; Coculture Techniques; Copper; Female; Fibroblasts; Humans; Metal Nanoparticles; Placenta; Pregnancy; Tellurium; Titanium; Trophoblasts

Using conventional scintillation detection, the fundamental limit in positron emission tomography (PET) time resolution is strongly dependent on the inherent temporal variances generated during the scintillation process, yielding an intrinsic physical limit for the coincidence time resolution of around 100 ps. On the other hand, modulation mechanisms of the optical properties of a material exploited in the optical telecommunications industry can be orders of magnitude faster. In this paper we borrow from the concept of optics pump-probe measurement to for the first time study whether ionizing radiation can produce modulations of optical properties, which can be utilized as a novel method for radiation detection. We show that a refractive index modulation of approximately [Formula: see text] is induced by interactions in a cadmium telluride (CdTe) crystal from a 511 keV photon source. Furthermore, using additional radionuclide sources, we show that the amplitude of the optical modulation signal varies linearly with both the detected event rate and average photon energy of the radiation source.

Topics: Cadmium Compounds; Monte Carlo Method; Optics and Photonics; Photons; Positron-Emission Tomography; Radiation, Ionizing; Tellurium

A black-hole quencher (BHQ-2) labeled DNA (Q-DNA) with a phosphorothioate backbone was covalently conjugated to the CdTe QDs during the QDs synthesis procedure. The hairpin structure of Q-DNA shortened the distance of the CdTe QDs and the BHQ-2 group, which resulted in fluorescence quenching of the QDs. The addition of target DNA or deoxyribonuclease I (DNase I) could move the BHQ-2 group away from the QDs. As a result, the fluorescence of the CdTe QDs recovered. This work provides a new way for target DNA and DNase I detection.

Topics: Biosensing Techniques; Cadmium Compounds; Deoxyribonuclease I; DNA; Fluorescence Resonance Energy Transfer; Nanoparticles; Particle Size; Quantum Dots; Surface Properties; Tellurium

A methodology for detection of the Cauliflower Mosaic Virus 35S(CaMV35S) promoter was developed to distinguish transgenic from non-transgenic soybean samples by using photoelectrochemical (PEC) biosensor. In this PEC biosensing system, the as-prepared gold nanoparticles-reduced graphene oxide acted as a nanocarrier to immobilize the thiol-functional probe (probe1), and the SiO

Topics: Biosensing Techniques; Cadmium Compounds; Caulimovirus; DNA Probes; DNA, Plant; Electrochemical Techniques; Fabaceae; Gold; Graphite; Light; Metal Nanoparticles; Oxides; Plants, Genetically Modified; Promoter Regions, Genetic; Quantum Dots; Silicon Dioxide; Tellurium; Viral Proteins

We report an efficient method to biosynthesize biocompatible cadmium telluride and cadmium sulphide quantum dots from the fungus Rhizopus stolonifer. The suspension of the quantum dots exhibited purple and greenish-blue luminescence respectively upon UV light illumination. Photoluminescence spectroscopy, X-ray diffraction, and transmission electron microscopy confirms the formation of the quantum dots. From the photoluminescence spectrum the emission maxima is found to be 424 and 476nm respectively. The X-ray diffraction of the quantum dots matches with results reported in literature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability evaluation carried out on 3-days transfer, inoculum 3×10

Topics: Animals; Biotechnology; Cadmium Compounds; Chalcogens; Green Chemistry Technology; Humans; MCF-7 Cells; Mice; Nanotechnology; NIH 3T3 Cells; Quantum Dots; Rhizopus; Sulfides; Tellurium

The increasing use of products derived from nanotechnology has raised concerns about their potential toxicity, especially at the immunocompetence level in organisms. This study compared the immunotoxicity of cadmium sulfate/cadmium telluride (CdS/Cd-Te) mixture quantum dots (QDs) and their dissolved components, cadmium chloride (CdCl2 )/sodium telluride (NaTeO3 ) salts, and a CdCl2 /NaTeO3 mixture on four animal models commonly used in risk assessment studies: one bivalve (Mytilus edulis), one fish (Oncorhynchus mykiss), and two mammals (mice and humans). Our results of viability and phagocytosis biomarkers revealed that QDs were more toxic than dissolved metals for blue mussels. For other species, dissolved metals (Cd, Te, and Cd-Te mixture) were more toxic than the nanoparticles (NPs). The most sensitive species toward QDs, according to innate immune cells, was humans (inhibitory concentration [IC50 ] = 217 μg/mL). However, for adaptative immunity, lymphoblastic transformation in mice was decreased for small QD concentrations (EC50 = 4 μg/mL), and was more sensitive than other model species tested. Discriminant function analysis revealed that blue mussel hemocytes were able to discriminate the toxicity of QDs, Cd, Te, and Cd-Te mixture (Partial Wilk's λ = 0.021 and p < 0.0001). For rainbow trout and human cells, the immunotoxic effects of QDs were similar to those obtained with the dissolved fraction of Cd and Te mixture. For mice, the toxicity of QDs markedly differed from those observed with Cd, Te, and dissolved Cd-Te mixture. The results also suggest that aquatic species responded more differently than vertebrates to these compounds. The results lead to the recommendation that mussels and mice were most able to discriminate the effects of Cd-based NPs from the effects of dissolved Cd and Te at the immunocompetence level.

Topics: Adaptive Immunity; Animals; Cadmium Compounds; Cell Survival; Cells, Cultured; Discriminant Analysis; Female; Hemocytes; Humans; Immunity, Innate; Leukocytes; Mice; Mice, Inbred C57BL; Mytilus edulis; Oncorhynchus mykiss; Phagocytosis; Quantum Dots; Species Specificity; T-Lymphocytes; Tellurium

High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred μm and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of μm, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 μm thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications.

Topics: Arsenicals; Cadmium Compounds; Gallium; Humans; Photons; Principal Component Analysis; Spectrometry, X-Ray Emission; Tellurium; Tomography, X-Ray Computed

Water-soluble thioglycolic acid (TGA)-capped core/shell CdTe/CdS quantum dots (QDs) were synthesized. The interactions of rhein and emodin with TGA-CdTe/CdS QDs were evaluated by fluorescence and ultraviolet-visible absorption spectroscopy. Experimental results showed that the high fluorescence intensity of TGA-CdTe/CdS QDs could be effectively quenched in the presence of rhein (or emodin) at 570 nm, which may have resulted from an electron transfer process from excited TGA-CdTe/CdS QDs to rhein (or emodin). The quenching intensity was in proportion to the concentration of both rhein and emodin in a certain range. Under optimized conditions, the linear ranges of TGA-CdTe/CdS QDs fluorescence intensity versus the concentration of rhein and emodin were 0.09650-60 µg/mL and 0.1175-70 µg/mL with a correlation coefficient of 0.9984 and 0.9965, respectively. The corresponding detection limits (3σ/S) of rhein and emodin were 28.9 and 35.2 ng/mL, respectively. This proposed method was applied to determine rhein and emodin in human urine samples successfully with remarkable advantages such as high sensitivity, short analysis time, low cost and easy operation. Based on this, a simple, rapid and highly sensitive method to determine rhein (or emodin) was proposed.

Topics: Anthraquinones; Cadmium Compounds; Emodin; Humans; Molecular Structure; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Sulfides; Surface Properties; Tellurium; Thioglycolates

Estimation of left ventricular ejection fraction (LVEF) with 99MTc-HSA equilibrium radionuclide angiography (RA) is frequently used for assessing cardiac function. The purpose of this study was to investigate the interstudy repeatability of left (LV) and right (RV) ventricular volume and ejection fraction estimations, using a cadmium-zinc-telluride (CZT) SPECT camera.. Forty-six patients were scanned twice, interrupted by repositioning. Each acquisition was analysed twice by two experienced technologists. Interstudy and interobserver variations were calculated as the coefficient of variation (CV) and the 95% confidence interval (CI) for limits of agreement (LOA) between each sequence of analyses for each of the two acquisitions.. The Interstudy variations and 95% CI for LVEF, LV end systolic (LVESV) and end diastolic (LVEDV) volumes were 4.6% (-5.4 to 6.4), 9.3% (-6.90 to 5.20) and 7.0% (-13.9 to 11.1), respectively. For the right ventricle, the corresponding values were 11.9% (-9.40 to 10.8), 9.8% (-14.9 to 10.8) and 8.1% (-20.7 to 16.3).. The CZT detector camera has excellent reproducibility with regard to interstudy variation when assessing LV volumes and EF. Interstudy variation is considerably higher for RV volumes and EF, indicating a lack of consistency in tracing the boarders of the right ventricle.

Topics: Adult; Aged; Aged, 80 and over; Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Female; Gamma Cameras; Gated Blood-Pool Imaging; Humans; Male; Middle Aged; Reproducibility of Results; Sensitivity and Specificity; Stroke Volume; Tellurium; Ultrasonography; Ventricular Dysfunction; Zinc Compounds

This study described a method for tracking and compensating respiratory motion in cadmium-zinc-telluride (CZT) cameras. We evaluated motion effects on myocardial perfusion imaging and assessed the usefulness of motion compensation in phantom and clinical studies.. SPECT studies were obtained from an oscillating heart phantom and 552 patients using CZT cameras with list-mode acquisition. Images were reformatted in 500-ms frames, and the activity centroid was calculated as respiratory signal. The myocardial perfusion, left ventricular (LV) wall thickness, and LV volume were assessed before and after the motion compensation technique.. In phantom studies, we documented only minimal bias between simulated and measured shifts. Significantly reduced tracer activity, increased wall thickness and decreased volume in scans with 15 mm or more axial shifts were noted. In clinical studies, there was a higher prevalence of significant motion after treadmill exercise. The motion compensation technique could successfully compensate those motion artifacts.. The described method allows for tracking and compensating respiratory motion in CZT cameras. Significant respiratory motion is still not uncommon using CZT cameras, especially in patients who underwent treadmill tests. Motion blurring can be compensated using image processing techniques and image quality could be significantly improved.

Topics: Aged; Algorithms; Artifacts; Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Female; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Information Storage and Retrieval; Male; Middle Aged; Motion; Phantoms, Imaging; Reproducibility of Results; Respiratory Mechanics; Respiratory-Gated Imaging Techniques; Sensitivity and Specificity; Tellurium; Tomography, Emission-Computed, Single-Photon; Ventricular Dysfunction, Left

A pH-sensitive and double functional nanoprobe was designed and synthesized in a water-soluble system using thioglycolic acid (TGA) and mercapto-acetohydrazide (TGH) as the stabilizers. TGA is biocompatible because the carboxyl group is easily linked to biological macromolecules. At the same time, the hydrazide on TGH reacts with the aldehyde on poly(ethylene glycol) (PEG) and forms a hydrazone bond. The hydrazone bond ruptured at specific pH values and exhibited pH-stimuli-responsive characteristics. As an optical imaging probe, the PEG-TGA/TGH-capped CdTe quantum dots (QDs) had high quality, with a fluorescence efficiency of 25-30%, and remained stable for at least five months. This pH-responsive factor can be used for the effective release of CdTe QDs under the acidic interstitial extracellular environment of tumor cells. This allows the prepared pH-stimuli-responsive nanoprobes to show fluorescence signals for use in cancer cell imaging.

Topics: Cadmium Compounds; Fluorescent Dyes; HeLa Cells; Hep G2 Cells; Humans; Hydrazones; Hydrogen-Ion Concentration; Microscopy, Fluorescence; Molecular Probes; Nanocomposites; Particle Size; Polyethylene Glycols; Quantum Dots; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Tellurium; Thioglycolates; X-Ray Diffraction

This novel materials assembly technology endows the designated materials with additional/enhanced performance by fixing "functional components" into the materials. Such functional components are molecularly recognized and accommodated by the designated materials. In this regard, two-photon fluorescence (TPF) organic molecules and CdTe quantum dots (QDs) are adopted as functional components to functionalize silk fibers and films. TPF organic molecules, such as, 2,7-bis[2-(4-nitrophenyl) ethenyl]-9,9-dibutylfluorene (NM), exhibit TPF emission quenching because of the molecular stacking that leads to aggregation in the solid form. The specific recognition between -NO2 in the annealed fluorescent molecules and the -NH groups in the silk fibroin molecules decouples the aggregated molecules. This gives rise to a significant increase in the TPF quantum yields of the silk fibers. Similarly, as another type of functional components, CdTe quantum dots (QDs) with different sizes were also adopted in the silk functionalization method. Compared to QDs in solution the fluorescence properties of functionalized silk materials display a long stability at room temperature. As the functional materials are well dispersed at high quantum yields in the biocompatible silk a TPF microscope can be used to pursue 3D high-resolution imaging in real time of the TPF-silk scaffold.

Topics: 3T3 Cells; Animals; Biocompatible Materials; Bombyx; Cadmium Compounds; Fibroins; Fluorenes; Materials Testing; Mice; Microscopy, Fluorescence; Nitrophenols; Photons; Protein Engineering; Quantum Dots; Quantum Theory; Solutions; Spectrometry, Fluorescence; Tellurium; Temperature

A sensitive fluorescence probing strategy for parathion-methyl (PM) detection was developed based on electron transfer (ET) between p-nitrophenol (the hydrolysate of PM) and CdTe quantum dots (QDs) in cetyltrimethylammonium bromide (CTAB). PM was hydrolyzed by organophosphorus hydrolase (OPH) to form p-nitrophenol. P-nitrophenol is a typically electron-deficient compound due to the strong electron-withdrawing effect of the nitro groups. The positive charge of CTAB which make it assemble with electronegative mercaptopropionic acid-capped QDs, could be used as an absorbent for p-nitrophenol due to the strong hydrophobic interaction between the long alkyl chain of CTAB and aromatic ring of p-nitrophenol. Thus, the fluorescence intensity of CdTe QDs/CTAB probe could be quenched by p-nitrophenol due to the ET mechanism. The fluorescence intensity of the QD/CTAB system was proportional to PM concentration in the range of 25-3000 ng mL(-1), with a detection limit of 18 ng mL(-1). Furthermore, the proposed method was simple in design and fast in operation, and has been successfully used for PM detection in environmental and agricultural samples with satisfactory recovery.

Topics: Cadmium Compounds; Cetrimonium; Cetrimonium Compounds; Fluorescent Dyes; Limit of Detection; Methyl Parathion; Nitrophenols; Oryza; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

Fluorescent cadmium telluride quantum dots (CdTe QDs) are an optically attractive option for bioimaging, but are known to display high cytotoxicity. Nanoparticles synthesized from chitosan, a natural biopolymer of β 1-4 linked glucosamine, display good biocompatibility and cellular uptake. A facile, green synthetic strategy has been developed to embed green fluorescent cadmium telluride quantum dots (CdTe QDs) in biocompatible CNPs to obtain a safer preparation than 'as is' QDs. High-resolution transmission electron microscopy showed the crystal lattice corresponding to CdTe QDs embedded in CNPs while thermogravimetry confirmed their polymeric composition. Electrostatic interactions between thiol-capped QDs (4 nm, -57 mV) and CNPs (~300 nm, +38 mV) generated CdTe QDs-embedded CNPs that were stable up to three months. Further, viability of NIH3T3 mouse fibroblast cells in vitro increased in presence of QDs-embedded CNPs as compared to bare QDs. At the highest concentration (10 μg/ml), the former shows 34 and 39% increase in viability at 24 and 48 h, respectively, as compared to the latter. This shows that chitosan nanoparticles do not release the QDs up to 48 h and do not cause extended toxicity. Furthermore, hydrolytic enzymes such as lysozyme and chitinase did not degrade chitosan nanoparticles. Moreover, QDs-embedded CNPs show enhanced internalization in NIH3T3 cells as compared to bare QDs. This method offers ease of synthesis and handling of stable, luminescent, biocompatible CdTe QDs-embedded CNPs with a favorable toxicity profile and better cellular uptake with potential for bioimaging and targeted detection of cellular components.

Topics: Animals; Biocompatible Materials; Biological Transport; Cadmium Compounds; Chitosan; Drug Stability; Fluorescent Dyes; Mice; Molecular Imaging; NIH 3T3 Cells; Optical Phenomena; Quantum Dots; Solubility; Solvents; Tellurium; Water

The exciton generation and recombination dynamics in semiconductor nanocrystals are very sensitive to small variations in dimensions, shape and surface capping. In the present work CdTe quantum dots are synthesized in water using 3-mercaptopropionic acid and 1-thioglycerol as stabilizers. Nanocrystals with an average dimension of 4.0 ± 1.0 and 3.7 ± 0.9 nm were obtained, when 3-mercaptopropionic acid or 1-thioglycerol, respectively, was used as a capping agent. The steady-state characterization shows that the two types of colloids have different luminescence behavior. In order to investigate the electronic structure and the dynamics of the exciton state, a combined study in the time domain has been carried out by using fluorescence time-correlated single photon counting and femtosecond transient absorption techniques. The electron-hole radiative recombination follows the non-exponential decay law for both colloids, which results in different average decay time values (of the order of tens of nanoseconds) for the two samples. The data demonstrate that the process is slower for 1-thioglycerol-stabilized colloids. The ultrafast transient absorption measurements are performed at two different excitation wavelengths (at the band gap and at higher energies). The spectra are dominated in both types of samples by the negative band-gap bleaching signals although transient positive absorption bands due to the electrons in the conduction band are observable. The analysis of the signals is affected by the different interactions with the defect states, due to ligand capping capacities. In particular, the data indicate that in 1-thioglycerol-stabilized colloids the non-radiative recombination processes are kinetically more competitive than the radiative recombination. Therefore the comparison of the data obtained from the two samples is interpreted in terms of the effects of the capping agents on the electronic relaxation of the colloids.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Electrons; Excipients; Glycerol; Luminescence; Photobleaching; Quantum Dots; Spectrum Analysis; Tellurium; Water

In this study, water-soluble CdTe quantum-dots (QDs) capped with glutathione (GSH) was synthesized. It was found that CdTe QDs could greatly enhance the chemiluminescence (CL) emission from the luminol-KMnO4 system in alkaline medium, and 4 nm CdTe QDs was used as catalysts to enhance the reaction sensitivity. The CL intensity of CdTe QDs-luminol-KMnO4 was strongly inhibited in the presence of 2-methoxyestradiol (2-ME) and the relative CL intensity was in linear correlation with the concentration of 2-ME. Based on this inhibition, a novel CL method with a lower detection limit and wider linear range was developed for the determination of 2-ME. The detection limit of plasma samples was 3.07×10(-10) g mL(-1) with a relative standard deviation of 0.24% for 8.0×10(-9) g mL(-1) 2-ME. The method was successfully applied for determination of 2-ME in plasma samples. The possible CL reaction mechanism was also discussed briefly.

Topics: 2-Methoxyestradiol; Animals; Cadmium Compounds; Estradiol; Kinetics; Luminescent Measurements; Luminol; Mice; Potassium Permanganate; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

Simple, inexpensive, portable sensing strategies for those clinically relevant molecules have attained a significant positive impact on the health care system. Herein, we have prepared a dual-emission ratiometric fluorescence probe with desired intensity ratio and demonstrated its efficiency for onsite naked eye determination of cysteine (Cys) and homocysteine (Hcy). The hybrid probe has been designed by hybridizing two differently sized CdTe quantum dots (QDs), in which the red-emitting CdTe QDs (rQDs) entrapped in the silica sphere acting as the reference signal, and the green-emitting CdTe QDs (gQDs) covalently attached on the silica surface serving as the response signal. When 1,10-phenanthroline with strong coordination ability to Cd atoms in gQDs was introduced, the fluorescence of the gQDs was effectively quenched, while the fluorescence of the rQDs stayed constant. Upon exposure to different contents of Cys or Hcy, the fluorescence of gQDs can be recovered gradually due to the displacement of the quencher. Based on the background signal of rQDs, the variations of the sensing system display continuous fluorescence color changes from red to green, which can be easily observed by the naked eye. The assay requires ∼20min and has a detection limit of 2.5 and 1.7μM for Cys and Hcy, respectively. Furthermore, we demonstrate that this sensing scheme can be fully integrated in a filter paper-based assay, thus enabling a potential point-of-care application featuring easy operation, low power consumption, and low fabrication costs.

Topics: Biosensing Techniques; Cadmium Compounds; Cysteine; Fluorescent Dyes; Homocysteine; Humans; Limit of Detection; Point-of-Care Systems; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Although many studies reporting the organ-level biodistribution of nanoparticles (NPs) in animals, very few have addressed the fate of NPs in organs at the cellular level. The liver appears to be the main organ for accumulation of NPs after intravenous injection. In this study, for the first time, the in vivo spatiotemporal disposition of recently developed mercaptosuccinic acid (MSA)-capped cadmium telluride/cadmium sulfide (CdTe/CdS) quantum dots (QDs) is explored in rat liver using multiphoton microscopy (MPM) coupled with fluorescence lifetime imaging (FLIM), with subcellular resolution (∼1 μm). With high fluorescence efficiency and largely improved stability in the biological environment, these QDs show a distinct distribution pattern in the liver compared to organic dyes, rhodamine 123 and fluorescein. After intravenous injection, fluorescent molecules are taken up by hepatocytes and excreted into the bile, while negatively charged QDs are retained in the sinusoids and selectively taken up by sinusoidal cells (Kupffer cells and liver sinusoidal endothelial cells), but not by hepatocytes within 3 h. The results could help design NPs targeting the specific types of liver cells and choose the fluorescent markers for appropriate cellular imaging.

Topics: Animals; Cadmium Compounds; Liver; Mice; Microscopy; Photons; Quantum Dots; Rats; Sulfides; Tellurium

Quantum dots not only act as nanocarrier but also act as stable and resistant natural fluorescent bio markers used in various in vitro and in vivo photolabelling and biological applications. In this study, the antimicrobial potential of TGA-CdTe QDs and commercial phenolics (rutin and caffeine) were investigated against Escherichiacoli. UV absorbance and fluorescence quenching study of TGA-CdTe QDs with rutin and caffeine complex was measured by spectroscopic technique. QDs-rutin conjugate exhibited excellent quenching property due to the -OH groups present in the rutin structure. But the same time caffeine has not conjugated with QDs because of lacking of -OH group in its structure. Photolabelling of E. coli with QDs-rutin and QDs-caffeine complex was analyzed by fluorescent microscopic method. Microbe E. coli cell membrane damage was assessed by atomic force (AFM) and confocal microscopy. Based on the results obtained, it is suggested that QDs-rutin conjugate enhance the antimicrobial activity more than the treatment with QDs, rutin and caffeine alone.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Caffeine; Escherichia coli; Microbial Sensitivity Tests; Microscopy, Atomic Force; Microscopy, Fluorescence; Quantum Dots; Rutin; Spectrometry, Fluorescence; Tellurium; Thioglycolates

A good understanding of the mechanism of interaction between quantum dots (QDs) and heavy metal ions is essential for the design of more effective sensor systems. In this work, CE was introduced to explore how l-cysteine-capped-CdTe QDs (l-cys-CdTe QDs) interacts with Hg(2+) . The change in electrophoretic mobility can synchronously reflect the change in the composition and property of QDs. The effects of the free and capping ligands on the system are discussed in detail. ESI-MS, dynamic light scattering (DLS), zeta potential, and fluorescence (FL) were also applied as cooperative tools to study the interaction mechanism. Furthermore, the interaction mechanism, which principally depended on the concentration of Hg(2+) , was proposed reasonably. At the low concentration of Hg(2+) , the formation of a static complex between Hg(2+) and the carboxyl and amino groups of l-cys-CdTe QDs surface was responsible for the FL quenching. With the increase of Hg(2+) concentration, the capping l-cys was stripped from the surface of l-cys-CdTe QDs due to the high affinity of Hg(2+) to the thiol group of l-cys. Our study demonstrates that CE can reveal the mechanism of the interaction between QDs and heavy metal ions, such as FL quenching.

Topics: Cadmium Compounds; Cysteine; Electrophoresis, Capillary; Mercury; Quantum Dots; Spectrometry, Mass, Electrospray Ionization; Tellurium

Semiconductor colloidal quantum dots (QDs) have been applied in biological analysis due to their unique optical properties and their versatility to be conjugated to biomolecules, such as lectins and antibodies, acquiring specificity to label a variety of targets. Concanavalin A (Con A) lectin binds specifically to α-d-mannose and α-d-glucose regions of saccharides that are usually expressed on membranes of mammalian cells and on cell walls of microbials. Candida albicans is the most common fungal opportunistic pathogen present in humans. Therefore, in this work, this fungus was chosen as a model for understanding cells and biofilm-forming organisms. Here, we report an efficient bioconjugation process to bind CdTe (Cadmium Telluride) QDs to Con A, and applied the bioconjugates to label saccharide structures on the cellular surface of C. albicans suspensions and biofilms. By accomplishing hemagglutination experiments and circular dichroism, we observed that the Con A structure and biochemical properties were preserved after the bioconjugation. Fluorescence microscopy images of yeasts and hyphae cells, as well as biofilms, incubated with QDs-(Con A) showed a bright orange fluorescence profile, indicating that the cell walls were specifically labeled. Furthermore, flow cytometry measurements confirmed that over 93% of the yeast cells were successfully labeled by QD-(Con A) complex. In contrast, non-conjugated QDs or QDs-(inhibited Con A) do not label any kind of biological system tested, indicating that the bioconjugation was specific and efficient. The staining pattern of the cells and biofilms demonstrate that QDs were effectively bioconjugated to Con A with specific labeling of saccharide-rich structures on C. albicans. Consequently, this work opens new possibilities to monitor glucose and mannose molecules through fluorescence techniques, which can help to optimize phototherapy protocols for this kind of fungus.

Topics: Cadmium Compounds; Candida albicans; Concanavalin A; Fluorescent Dyes; Glucose; Mannose; Microscopy, Fluorescence; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thiomalates

In this study, canine kidney cells (MDCK) are fluorescently labeled by carboxymethyl chitosan-coated CdTe quantum dots to obtain a stable fluorescence. Fluorescently labeled MDCK cells are incubated with Hg(2+) and passed flow cytometer to measure the mean fluorescence intensity, which shows [Hg(2+)] has a prominent quenching ability on the cells' fluorescence. The dose-dependent relation can be described by Stern-Volmer equation at the concentration range of 5-70 μg/L [Hg(2+)]. This method can be employed to determine the concentration of Hg(2+) in living cells by measuring the changes in fluorescence of the cellular system. The results show a relative standard deviation of 7.16% (n=11) and a recovery rate ranging from 92% to 103%, indicating a promising prospect of application on real-time in-situ analysis of [Hg(2+)] and its cytotoxic effects.

Topics: Animals; Cadmium Compounds; Chitosan; Computer Systems; Dogs; Madin Darby Canine Kidney Cells; Mercury; Quantum Dots; Spectrometry, Fluorescence; Staining and Labeling; Tellurium

The impact of strain on the optical properties of semiconductor quantum dots (QDs) is fundamentally important while still awaiting detailed investigation. CdTe/CdS core/shell QDs represent a typical strained system due to the substantial lattice mismatch between CdTe and CdS. To probe the strain-related effects, aqueous CdTe/CdS QDs were synthesized by coating different sized CdTe QD cores with CdS shells upon the thermal decomposition of glutathione as a sulfur source under reflux. The shell growth was carefully monitored by both steady-state absorption and fluorescence spectroscopy and transient fluorescence spectroscopy. In combination with structural analysis, the band alignments as a consequence of the strain were modified based on band deformation potential theory. By further taking account of these strain-induced band shifts, the effective mass approximation (EMA) model was modified to simulate the electronic structure, carrier spatial localization, and electron-hole wave function overlap for comparing with experimentally derived results. In particular, the electron/hole eigen energies were predicted for a range of structures with different CdTe core sizes and different CdS shell thicknesses. The overlap of electron and hole wave functions was further simulated to reveal the impact of strain on the electron-hole recombination kinetics as the electron wave function progressively shifts into the CdS shell region while the hole wave function remains heavily localized in CdTe core upon the shell growth. The excellent agreement between the strain-modified EMA model with the experimental data suggests that strain exhibits remarkable effects on the optical properties of mismatched core/shell QDs by altering the electronic structure of the system.

Topics: Cadmium Compounds; Electrons; Kinetics; Models, Molecular; Molecular Conformation; Optical Phenomena; Quantum Dots; Quantum Theory; Sulfides; Tellurium

A sensitive fluorescence biosensor for determining sparfloxacin (SPF) based on the electron transfer mechanism and the fluorescence quenching effect of SPF to cadmium telluride quantum dots (CdTe QDs) was developed. The mechanism of the interaction between SPF and CdTe QDs was investigated by UV/Vis absorption and fluorescence spectroscopy. The biosensor could be used for the determination of SPF with a high sensitivity. Under optimum conditions, the linear range was from 0.28 to 40 μg SPF ml(-1) with a correlation coefficient of 0.9983, and the detection limit (3δ/k) was 83.7 ng SPF ml(-1). Furthermore, this method has been applied to the determination of SPF in the synthetic environmental water samples and the spiked human serum samples with good results.

Topics: Antitubercular Agents; Biosensing Techniques; Cadmium Compounds; Fluorescence; Fluoroquinolones; Humans; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

Local and rapid heating by microwave (MW) irradiation is important in the clinical treatment of tumors using hyperthermia. We report here a new thermo-seed technique for the highly efficient MW irradiation ablation of tumors in vivo based on gelatin microcapsules. We achieved 100% tumor elimination in a mouse model at an ultralow power of 1.8 W without any side-effects. The results of MTT assays, a hemolysis test and the histological staining of organs indicated that the gelatin microcapsules showed excellent compatibility with the physiological environment. A possible mechanism is proposed for MW hyperthermia using gelatin microcapsules. We also used gelatin microcapsules capped with CdTe quantum dots for in vivo optical imaging. Our study suggests that these microcapsules may have potential applications in imaging-guided cancer treatment.

Topics: Animals; Biocompatible Materials; Cadmium Compounds; Cell Survival; Colloids; Erythrocyte Membrane; Erythrocytes; Female; Fluorescent Dyes; Gelatin; Hemolysis; Hep G2 Cells; Humans; Hyperthermia, Induced; L-Lactate Dehydrogenase; Mice; Mice, Inbred ICR; Microscopy, Electron, Scanning; Microwaves; Neoplasm Transplantation; Neoplasms; Optics and Photonics; Quantum Dots; Rabbits; Spectroscopy, Fourier Transform Infrared; Tellurium; Tissue Distribution

In this work, a fluorometric approach for the selective determination of calcium by using CdTe nanocrystals as chemosensors, was developed. The quantum dots interacted not with the metal, but with a ligand that also bonded the metal. The fluorescence response was modulated by the extension of the competitive metal-ligand binding, and therefore the amount of free ligand. CdTe quantum dots (QDs) with different capping layers were evaluated, as the QDs surface chemistry and capping nature affected recognition, thus the magnitude of the ensuing fluorescence quenching. The developed procedure was automated by using a multipumping flow system. Upon optimization, thioglycolic acid (TGA) and EDTA were selected as capping and ligand, respectively, providing a linear working range for calcium concentrations between 0.80-3.20 mg L(-1), and a detection limit of 0.66 mg L(-1). A quenching mechanism relying on nanocrystal destabilization upon detachment of surface Cd by the ligand was proposed.

Topics: Binding, Competitive; Cadmium Compounds; Calcium; Cations, Divalent; Drinking Water; Edetic Acid; Fluorescence; Fluorometry; Humans; Ligands; Limit of Detection; Quantum Dots; Tellurium; Thioglycolates

The development of photoelectrochemical (PEC) sensors with novel principles is of significance in realizing sensitive and low-cost detection. This work uses CuO NPs labeled antibody to construct a simple and sensitive sandwich-type immunobiosensor for the detection of protein. The detection signal is produced by dissolving the CuO NPs to release copper ions, which are then added on a quantum dots (QDs) modified F-doped tin oxide to quench the photocurrent of QDs via copper ion-induced formation of exciton trapping. The formed exciton trapping blocks the escape of photoelectron and thus leads to a "signal off" PEC method for sensitive immunoassay. The proposed method shows a detectable range from 0.05 to 500 ng/mL for α-fetoprotein (AFP) with a detection limit (LOD) of 0.038 ng/mL. This work further extends the application of exciton trapping-based PEC biosensing strategy in bioanalysis. The sensitive analytical performance of the designed route implies a promising potential of the PEC sensing in clinical diagnosis.

Topics: alpha-Fetoproteins; Antibodies; Biosensing Techniques; Cadmium Compounds; Copper; Electrochemical Techniques; Immunoassay; Metal Nanoparticles; Photochemical Processes; Quantum Dots; Tellurium

A new chemiluminescence (CL) flow method for persulfate determination was developed based on luminol oxidation by in-line generated radicals. Reactive oxygen species (ROS) generated by CdTe quantum dots (QDs) under a low energetic radiation (visible light emitted by LEDs) promoted the decomposition of persulfate ion (S2O8(2-)) into sulfate radical (SO4(∙-)), leading to subsequent radical chain reactions that yield the emission of light. Due to the inherent radical short lifetimes and the transient behavior of CL phenomena an automated multi-pumping flow system (MPFS) was proposed to improve sample manipulation and reaction zone implementation ensuring reproducible analysis time and high sampling rate. The developed approach allowed up to 60 determinations per hour and determine S2O8(2-) concentrations between 0.1 and 1 mmol with good linearity (R=0.9999). The method has shown good repeatability with relative standard deviations below 2.5% (n=3) for different persulfate concentrations (0.1 and 0.625 mmol L(-1)). Limits of detection (3σ) and quantification (10σ) were 2.7 and 9.1 µmol L(-1), respectively. The MPFS system was applied to persulfate determination in bench scale UV/S2O8(2-) drug degradation processes of model samples showing good versatility and providing real time information on the persulfate consumption in photo-chemical degradation methodologies.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Light; Luminol; Nanoparticles; Oxidation-Reduction; Potassium Compounds; Quantum Dots; Reactive Oxygen Species; Sulfates; Tellurium

Water-soluble glutathione (GSH)-capped CdTe quantum dots (QDs) were synthesized. In pH 7.1 PBS buffer solution, the interaction between GSH-capped CdTe QDs and fenbendazole (FBZ) was investigated by spectroscopic methods, including fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, and resonance Rayleigh scattering (RRS) spectroscopy. In GSH-capped CdTe QDs solution, the addition of FBZ results in the fluorescence quenching and RRS enhancement of GSH-capped CdTe QDs. And the quenching intensity (enhanced RRS intensity) was proportional to the concentration of FBZ in a certain range. Investigation of the interaction mechanism, proved that the fluorescence quenching and RRS enhancement of GSH-capped CdTe QDs by FBZ is the result of electrostatic attraction. Based on the quenching of fluorescence (enhancement of RRS) of GSH-capped CdTe QDs by FBZ, a novel, simple, rapid and specific method for FBZ determination was proposed. The detection limit for FBZ was 42 ng mL(-1) (3.4 ng mL(-1)) and the quantitative determination range was 0-2.8 μg mL(-1) with a correlation of 0.9985 (0.9979). The method has been applied to detect FBZ in real simples and with satisfactory results.

Topics: Acids; Cadmium Compounds; Ethanol; Fenbendazole; Glutathione; Kinetics; Light; Models, Molecular; Nanoparticles; Quantum Dots; Scattering, Radiation; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Time Factors

A multifunctional aptasensor for highly sensitive and one-step rapid detection of ochratoxin A (OTA), has been developed using aptamer-conjugated magnetic beads (MBs) as the recognition and concentration element and a heavy CdTe quantum dots (QDs) as the label. Initially, the thiolated aptamer was conjugated on the Fe3O4@Au MBs through Au-S covalent binding. Subsequently, multiple CdTe QDs were loaded both in and on a versatile SiO2 nanocarrier to produce a large amplification factor of hybrid fluorescent nanoparticles (HFNPs) labeled complementary DNA (cDNA). The magnetic-fluorescent-targeting multifunctional aptasensor was thus fabricated by immobilizing the HFNPs onto MBs' surface through the hybrid reaction between the aptamer and cDNA. This aptasensor can be produced at large scale in a single run, and then can be conveniently used for rapid detection of OTA through a one-step incubation procedure. The presence of OTA would trigger aptamer-OTA binding, resulting in the partial release of the HFNPs into bulk solution. After a simple magnetic separation, the supernatant liquid of the above solution contained a great number of CdTe QDs produced an intense fluorescence emission. Under the optimal conditions, the fluorescence intensity of the released HFNPs was proportional to the concentration of OTA in a wide range of 15 pg mL(-1) -100 ng mL(-1) with a detection limit of 5.4 pg mL(-1) (S/N=3). This multifunctional aptasensor represents a promising path toward routine quality control of food safety, and also creates the opportunity to develop aptasensors for other targets using this strategy.

Topics: Aptamers, Nucleotide; Biosensing Techniques; Cadmium Compounds; DNA, Complementary; Food Analysis; Humans; Limit of Detection; Magnetic Phenomena; Ochratoxins; Quantum Dots; Silicon Dioxide; Tellurium

Mercaptopropionic acid (MPA)-capped cadmium telluride (CdTe) quantum dot (QDs) fluorescent probes were synthesized in aqueous solution and used for the determination of salicylic acid. The interaction between the MPA-capped CdTe QDs and salicylic acid was studied using fluorescence spectroscopy and some parameters that could modify the fluorescence were investigated to optimize the measurements. Under optimum conditions, the quenched fluorescence intensity of MPA-capped CdTe QDs was linearly proportional to the concentration of salicylic acid in the range of 0.5-40 µg mL(-1) with a coefficient of determination of 0.998, and the limit of detection was 0.15 µg mL(-1). The method was successfully applied to the determination of salicylic acid in pharmaceutical products, and satisfactory results were obtained that were in agreement with both the high pressure liquid chromatography (HPLC) method and the claimed values. The recovery of the method was in the range 99 ± 3% to 105 ± 9%. The proposed method is simple, rapid, cost effective, highly sensitivity and eminently suitable for the quality control of pharmaceutical preparation. The possible mechanisms for the observed quenching reaction was also discussed.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Fluorescent Dyes; Molecular Structure; Pharmaceutical Preparations; Quantum Dots; Salicylic Acid; Tellurium

A sensitive and simple analytical strategy for the detection of sodium cromoglycate (SCG) has been established based on a readily detectable fluorescence quenching effect of SCG for glutathione-capped (GSH-capped) CdTe quantum dots (QDs). The fluorescence of GSH-capped CdTe QDs could be efficiently quenched by SCG through electron transfer from GSH-capped CdTe QDs to SCG. Under optimum conditions, the response was linearly proportional to the concentration of SCG between 0.6419 and 100 µg/mL, with a correlation coefficient (R) of 0.9964; the detection limit (3δ/K) was 0.1926 µg/mL. The optimum conditions and the influence of coexisting foreign substances on the reaction were also investigated. The very effective and simple method reported here has been successfully applied to the determination of SCG in synthetic and real samples. It is believed that the established approach could have good prospects for application in the fields of clinical diseases diagnosis and treatment.

Topics: Cadmium Compounds; Cromolyn Sodium; Fluorescent Dyes; Glutathione; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium

Water-soluble multidentate polymer coated CdTe quantum dots (QDs) were prepared via a stepwise addition of raw materials in a one-pot aqueous solution under ambient conditions. Just by adjusting the compositions of raw materials, different sized CdTe QDs were achieved within a short time. The as-prepared QDs showed compact surface coating (1.6-1.8 nm) of polymer ligands and photoluminescence (PL) emitted at 533-567 nm, as well as high colloidal/photo-stability and quantum yields (58-67%). Moreover, these QDs exhibited significant upconversion luminescence (UCL) upon excitation using an 800 nm femtosecond laser. Experimental results confirm that the UCL was ascribed to the two-photon assisted process via a virtual energy state. Then, the two-photon excited QDs were further developed as a novel UCL probe of dopamine (DA) due to self-assembled binding of DA molecules with QDs via non-covalent bonding. As a receptor, the DA attached onto the QD surface induced an electron transfer from QDs to DA, triggering UCL quenching of QDs. This UCL probe of DA presented a low limit of detection (ca. 5.4 nM), and high selectivity and sensitivity in the presence of potential interferences. In particular, it was favorably applied to the detection of DA in biological fluids, with quantitative recoveries (96.0-102.6%).

Topics: Animals; Cadmium Compounds; Cattle; Dopamine; Dopamine Agents; Humans; Luminescent Agents; Luminescent Measurements; Photons; Polymers; Quantum Dots; Surface Properties; Tellurium

One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images.

Topics: Cadmium Compounds; Diffusion; Hydrodynamics; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Core-shell CdTe/ZnS quantum dots capped with 3-mercaptopropionic acid (MPA) were successfully synthesized in aqueous medium by hydrothermal synthesis. These quantum dots have advantages compared to traditional quantum dots with limited biological applications, high toxicity and tendency to aggregate. The concentration of Cu(2+) has a significant impact on the fluorescence intensity of quantum dots (QDs), therefore, a rapid sensitive and selective fluorescence probe has been proposed for the detection of Cu(2+) in aqueous solution. Under optimal conditions, the fluorescence intensity of CdTe/ZnS QDs was linearly proportional to the concentration of Cu(2+) in the range from 2.5 × 10(-9) M to 17.5 × 10(-7) M with the limit of 1.5 × 10(-9) M and relative standard deviation of 0.23%. The quenching mechanism is static quenching with recoveries of 97.30-102.75%.

Topics: Cadmium Compounds; Copper; Fluorescence; Fluorescent Dyes; Quantum Dots; Spectrophotometry; Sulfides; Tellurium; Zinc Compounds

Cadmium telluride (CdTe) and cadmium selenide (CdSe) are increasingly being applied in photovoltaic solar cells and electronic components. A major concern is the public health and ecological risks associated with the potential release of toxic cadmium, tellurium, and/or selenium species. In this study, different tests were applied to investigate the leaching behavior of CdTe and CdSe in solutions simulating landfill leachate. CdTe showed a comparatively high leaching potential. In the Toxicity Characteristic Leaching Procedure (TCLP) and Waste Extraction Test (WET), the concentrations of cadmium released from CdTe were about 1500 and 260 times higher than the regulatory limit (1 mg/L). In contrast, CdSe was relatively stable and dissolved selenium in both leaching tests was below the regulatory limit (1 mg/L). Nonetheless, the regulatory limit for cadmium was exceeded by 5- to 6- fold in both tests. Experiments performed under different pH and redox conditions confirmed a marked enhancement in CdTe and CdSe dissolution both at acidic pH and under aerobic conditions. These findings are in agreement with thermodynamic predictions. Taken as a whole, the results indicate that recycling of decommissioned CdTe-containing devices is desirable to prevent the potential environmental release of toxic cadmium and tellurium in municipal landfills.

Topics: Cadmium Compounds; Electronic Waste; Hydrogen-Ion Concentration; Oxidation-Reduction; Selenium Compounds; Tellurium; Water Pollutants, Chemical

Recent experimental studies have identified at least two nonradiative components in the fluorescence decay of solutions of CdTe colloidal quantum dots (CQDs). The lifetimes reported by different groups, however, differed by orders of magnitude, raising the question of whether different types of traps were at play in the different samples and experimental conditions and even whether different types of charge carriers were involved in the different trapping processes. Considering that the use of these nanomaterials in biology, optoelectronics, photonics, and photovoltaics is becoming widespread, such a gap in our understanding of carrier dynamics in these systems needs addressing. This is what we do here. Using the state-of-the-art atomistic semiempirical pseudopotential method, we calculate trapping times and nonradiative population decay curves for different CQD sizes considering up to 268 surface traps. We show that the seemingly discrepant experimental results are consistent with the trapping of the hole at unsaturated Te bonds on the dot surface in the presence of different dielectric environments. In particular, the observed increase in the trapping times following air exposure is attributed to the formation of an oxide shell on the dot surface, which increases the dielectric constant of the dot environment. Two types of traps are identified, depending on whether the unsaturated bond is single (type I) or part of a pair of dangling bonds on the same Te atom (type II). The energy landscape relative to transitions to these traps is found to be markedly different in the two cases. As a consequence, the trapping times associated with the different types of traps exhibit a strikingly contrasting sensitivity to variations in the dot environment. Based on these characteristics, we predict the presence of a sub-nanosecond component in all photoluminescence decay curves of CdTe CQDs in the size range considered here if both trap types are present. The absence of such a component is attributed to the suppression of type I traps.

Topics: Cadmium Compounds; Colloids; Electrons; Kinetics; Luminescent Measurements; Models, Molecular; Molecular Conformation; Particle Size; Photons; Quantum Dots; Surface Properties; Tellurium

Non-invasive dual energy methods have been used extensively on osteoporosis diagnosis estimating parameters, such as, Bone Mineral Density (BMD) and Bone Mineral Content (BMC). In this study, an X-ray dual energy method (XRDE) was developed for the estimation of the bone Calcium-to-Phosphorous (Ca/P) mass ratio, as a bone quality index. The optimized irradiation parameters were assessed by performing analytical model simulations. X-ray tube output, filter material and thickness were used as input parameters. A single exposure technique, combined with K-edge filtering, was applied. The optimal X-ray spectra were selected according to the resulted precision and accuracy values. Experimental evaluation was performed on an XRDE system incorporating a Cadmium Telluride (CdTe) photon counting detector and three bone phantoms with different nominal mass Ca/P ratios. Additionally, the phantoms' mass Ca/P ratios were validated with energy-dispersive X-ray spectroscopy (EDX). Simulation results showed that the optimum filter atomic number (Z) ranges between 57 and 70. The optimum spectrum was obtained at 100 kVp, filtered with Cerium (Ce), with a surface density of 0.88 g/cm(2). All Ca/P ratio measurements were found to be accurate to within 1.6% of the nominal values, while the precision ranged between 0.91 and 1.37%. The accuracy and precision values of the proposed non-invasive method contributes to the assessment of the bone quality state through the mass Ca/P ratio determination.

Topics: Absorptiometry, Photon; Bone and Bones; Bone Density; Cadmium Compounds; Calcium; Humans; Osteoporosis; Phantoms, Imaging; Phosphorus; Tellurium

Currently, metallothioneins (MTs) are extensively investigated as the molecular biomarkers and the significant positive association of the MT amount was observed in tumorous versus healthy tissue of various types of malignant tumors, including head and neck cancer. Thus, we proposed a biosensor with fluorescence detection, comprising paramagnetic nanoparticles (nanomaghemite core with gold nanoparticles containing shell) for the magnetic separation of MT, based on affinity of its sulfhydryl groups toward gold. Biosensor was crafted from PDMS combined with technology of 3D printing and contained reservoir with volume of 50 μL linked to input (sample/detection components and washing/immunobuffer) and output (waste). For the immunolabeling of immobilized MT anti-MT antibodies conjugated to CdTe quantum dots through synthetic heptapeptide were employed. After optimization of fundamental conditions of the immunolabeling (120 min, 20°C, and 1250 rpm) we performed it on a surface of paramagnetic nanoparticles in the biosensor reservoir, with evaluation of fluorescence of quantum dots (λexc 400 nm, and λem 555 nm). The developed biosensor was applied for quantification of MT in cell lines derived from spinocellular carcinoma (cell line 122P-N) and fibroblasts (122P-F) and levels of the biomarker were found to be about 90 nM in tumor cells and 37 nM in fibroblasts. The proposed system is able to work with low volumes (< 100 μL), with low acquisition costs and high portability.

Topics: Biosensing Techniques; Cadmium Compounds; Cell Line, Tumor; Dimethylpolysiloxanes; Fluorescence; Gold; Humans; Magnetics; Metal Nanoparticles; Metallothionein; Neoplasms; Printing, Three-Dimensional; Quantum Dots; Tellurium

A fluorescent "turn off-on" pattern for the detection of herring sperm DNA (hsDNA) had been designed through utilizing the interaction between polymyxin B sulfate (PMBS) and hsDNA as an inherent performance and the fluorescent transformation of glutathione (GSH)-capped CdTe quantum dots (QDs) as an external manifestation. Due to the occurrence of the photoinduced electron transfer from the QDs to PMBS, the fluorescence of GSH-capped CdTe QDs could be effectively quenched by PMBS, causing the system into "off" state. With the addition of hsDNA, the quenched fluorescence of GSH-capped CdTe QDs could be restored for the reason that PMBS embedded into hsDNA double helix structure to form new complex and peeled off from the surface of GSH-capped CdTe QDs, leading the system into "on" condition. Corresponding experimental results illustrated that the relative recovered fluorescence intensity of GSH-capped CdTe QDs-PMBS system was near proportional to the concentration of hsDNA within the range of 0.059-15.0 μg mL(-1). This proposed method demonstrated a good linear correlation coefficient of 0.9937 and a detection limit (3 σ/K) of 0.018 μg mL(-1) for hsDNA. This dual-directional fluorescent biosensor overcame the selectivity problem commonly existed in the traditional mono-directional fluorescence detection mode and owned perfect analysis applications in biochemical DNA monitoring.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; DNA; Electron Transport; Electrons; Fishes; Glutathione; Limit of Detection; Polymyxin B; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) are increasingly applied in sensing, drug delivery, biomedical imaging, electronics industries, etc. Consequently, it is urgently required to examine their potential threat to humans and the environment. In the present work, the toxicity of CdTe QDs with nearly identical maximum emission wavelength but modified with two different ligands (MPA and BSA) to mitochondria was investigated using flow cytometry, spectroscopic, and microscopic methods. The results showed that QDs induced mitochondrial permeability transition (MPT), which resulted in mitochondrial swelling, collapse of the membrane potential, inner membrane permeability to H(+) and K(+), the increase of membrane fluidity, depression of respiration, alterations of ultrastructure, and the release of cytochrome c. Furthermore, the protective effects of CsA and EDTA confirmed QDs might be able to induce MPT via a Ca(2+)-dependent domain. However, the difference between the influence of CdTe QDs and that of Cd(2+) on mitochondrial membrane fluidity indicated the release of Cd(2+) was not the sole reason that QDs induced mitochondrial dysfunction, which might be related to the nanoscale effect of QDs. Compared with MPA-CdTe QDs, BSA-CdTe QDs had a greater effect on the mitochondrial swelling, membrane fluidity, and permeabilization to H(+) and K(+) by mitochondrial inner membrane, which was caused the fact that BSA was more lipophilic than MPA. This study provides an important basis for understanding the mechanism of the toxicity of CdTe QDs to mitochondria, and valuable information for safe use of QDs in the future.

Topics: Animals; Cadmium Compounds; Mitochondria, Liver; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Permeability Transition Pore; Phenylacetates; Quantum Dots; Rats; Rats, Wistar; Serum Albumin, Bovine; Tellurium

There are an increasing number of studies indicating that mitochondria are relevant targets in nanomaterial-induced toxicity. However, the underlying mechanisms by which nanoparticles (NPs) interact with these organelles and affect their functions are unknown. The aim of this study was to investigate the effects of cadmium telluride quantum dot (CdTe-QD) NPs on mitochondria in human hepatocellular carcinoma HepG2 cells. CdTe-QD treatment resulted in the enlargement of mitochondria as examined with transmission electron microscopy and confocal microscopy. CdTe-QDs appeared to associate with the isolated mitochondria as detected by their inherent fluorescence. Further analyses revealed that CdTe-QD caused disruption of mitochondrial membrane potential, increased intracellular calcium levels, impaired cellular respiration, and decreased adenosine triphosphate synthesis. The effects of CdTe-QDs on mitochondrial oxidative phosphorylation were evidenced by changes in levels and activities of the enzymes of the electron transport chain. Elevation of peroxisome proliferator-activated receptor-γ coactivator levels after CdTe-QD treatment suggested the effects of CdTe-QDs on mitochondrial biogenesis. Our results also showed that the effects of CdTe-QDs were similar or greater to those of cadmium chloride at equivalent concentrations of cadmium, suggesting that the toxic effects of CdTe-QDs were not solely due to cadmium released from the NPs. Overall, the study demonstrated that CdTe-QDs induced multifarious toxicity by causing changes in mitochondrial morphology and structure, as well as impairing their function and stimulating their biogenesis.

Topics: Cadmium Compounds; Hep G2 Cells; Hepatocytes; Humans; Microscopy, Electron, Transmission; Mitochondria; Nanoparticles; Quantum Dots; Tellurium

To investigate the dose saving potential of direct-converting CdTe photon-counting detector technology for dedicated breast CT.. We analyzed the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) of two detector technologies, suitable for breast CT (BCT): a flat-panel energy-integrating detector with a 70 μm and a 208 μm thick gadolinium oxysulfide (GOS) and a 150 μm thick cesium iodide (CsI) scintillator and a photon-counting detector with a 1000 μm thick CdTe sensor.. The measurements for GOS scintillator thicknesses of 70 μm and 208 μm delivered 10% pre-sampled MTF values of 6.6 mm(-1) and 3.2 mm(-1), and DQE(0) values of 23% and 61%. The 10% pre-sampled MTF value for the 150 μm thick CsI scintillator 6.9 mm(-1), and the DQE(0) value was 49%. The CdTe sensor reached a 10% pre-sampled MTF value of 8.5 mm(-1) and a DQE(0) value of 85%.. The photon-counting CdTe detector technology allows for significant dose reduction compared to the energy-integrating scintillation detector technology used in BCT today. Our comparative evaluation indicates that a high potential dose saving may be possible for BCT by using CdTe detectors, without loss of spatial resolution.

Topics: Breast; Cadmium Compounds; Mammography; Radiation Dosage; Scintillation Counting; Signal-To-Noise Ratio; Tellurium

New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD) nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD-platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro.

Topics: Blood Platelets; Cadmium Compounds; Cell Membrane; Flow Cytometry; Humans; Matrix Metalloproteinase 2; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nanostructures; P-Selectin; Platelet Activation; Quantum Dots; Quartz; Quartz Crystal Microbalance Techniques; Tellurium

Quantum dots (QDs) as potent candidates possess advantageous superiority in fluorescence imaging applications, but they are susceptible to the biological circumstances (e.g., bacterial environment), leading to fluorescence quenching or lose of fluorescent properties. In this work, CdTe QDs were embedded into mesoporous silica nanospheres (m-SiO2 NSs) for preventing QD agglomeration, and then CdTe QD-embedded m-SiO2 NSs (m-SiO2/CdTe NSs) were modified with Ag nanoparticles (Ag NPs) to prevent bacteria invasion for enhanced anticounterfeit applications. The m-SiO2 NSs, which serve as intermediate layers to combine CdTe QDs with Ag NPs, help us establish a highly fluorescent and long-term antibacterial system (i.e., m-SiO2/CdTe/Ag NSs). More importantly, CdTe QD-embedded m-SiO2 NSs showed fluorescence quenching when they encounter bacteria, which was avoided by attaching Ag NPs outside. Ag NPs are superior to CdTe QDs for preventing bacteria invasion because of the structure (well-dispersed Ag NPs), size (small diameter), and surface charge (positive zeta potentials) of Ag NPs. The plausible antibacterial mechanisms of m-SiO2/CdTe/Ag NSs toward both Gram-positive and Gram-negative bacteria were established. As for potential applications, m-SiO2/CdTe/Ag NSs were developed as fluorescent anticounterfeiting ink for enhanced imaging applications.

Topics: Anti-Bacterial Agents; Bacteria; Cadmium Compounds; Escherichia coli; Metal Nanoparticles; Microbial Sensitivity Tests; Microscopy, Fluorescence; Nanospheres; Particle Size; Porosity; Quantum Dots; Silicon Dioxide; Silver; Staphylococcus aureus; Tellurium; Ultraviolet Rays; X-Ray Diffraction

A novel fluorescent biosensor is developed, based on glutathione-capped CdTe quantum dots aggregation, for the determination of trace amount of an important drug, protamine. In this method with increasing the protamine concentration, the fluorescence of the quantum dots was quenched due to their aggregation. Different parameters affect the sensitivity, such as pH and the amount of the quantum dots, were optimized. Using the new optical biosensor, under the optimized conditions, protamine could be measured in the range of 2.0-200 ng mL(-1) with a detection limit of 1.0 ng mL(-)(1). The relative standard deviation for five replicates determination of 30.0 ng mL(-)(1) protamine was 1.26%. The influence of common interfering species on the protamine detection was studied. The results showed that the biosensor is highly selective and sensitive for the detection of protamine. The optical biosensor was successfully used for the determination of protamine in real samples.

Topics: Biosensing Techniques; Cadmium Compounds; Glutathione; Heparin Antagonists; Humans; Limit of Detection; Protamines; Quantum Dots; Spectrometry, Fluorescence; Tellurium

It was found that cadmium telluride (CdTe) quantum dots (QDs) with different sizes can have a great sensitizing effect on chemiluminescence (CL) emission from luminol-potassium periodate (KIO4) system. Levodopa, a widely prescribed drug in the treatment of Parkinson's disease, could inhibit luminol-KIO4-CdTe QDs CL reaction in alkaline solution. The inhibited CL intensity was proportional to the concentration of levodopa in the range from 8.0 nM to 10.0 μM. The detection limit was 3.8 nM. This method has been successfully applied to determine levodopa in pharmaceutical preparation and human urine and plasma samples with recoveries of 94.1-105.4%. This was the first work for inhibition effect determination of levodopa using a QD-based CL method.

Topics: Cadmium Compounds; Equipment Design; Humans; Levodopa; Limit of Detection; Linear Models; Luminescent Measurements; Luminol; Particle Size; Periodic Acid; Potassium Compounds; Quantum Dots; Reproducibility of Results; Tellurium

Changes of the photoluminescent properties of QD in the presence of oxidized catechin (CQ) were investigated by absorption, steady-state fluorescence, fluorescence lifetime and dynamic light scattering measurements. Photoluminescence intensity and fluorescence lifetime was decreasing with increasing CQ concentration. Dynamic light scattering technique found the hydrodynamic diameter of QD suspension in water is in range of 45 nm, whereas in presence of CQ increased to mean values of 67 nm. Calculated from absorption peak position of excition band indicated on average QD size of 3.2 nm. Emission spectroscopy and time-resolved emission studies confirmed preservation of electronic band structure in QD-CQ aggregates. On basis of the presented results, the elucidated mechanism of QD fluorescence quenching is a result of the interaction between QD and CQ due to electron transfer and electrostatic attraction. The results of fluorescence quenching of water-soluble CdTe quantum dot (QD) capped with thiocarboxylic acid were used to implement a simple and fast method to determine the presence of native antioxidant quinones in aqueous solutions. Feasibility studies on this method carried out with oxidized catechin showed a linear relation between the QD emission and quencher concentration, in range from 1 up to 200 μM. The wide linear range of concentration dependence makes it possible to apply this method for the fast and sensitive detection of quinones in solutions.

Topics: Cadmium Compounds; Catechin; Dynamic Light Scattering; Feasibility Studies; Luminescence; Oxidation-Reduction; Quantum Dots; Quinones; Solutions; Spectrometry, Fluorescence; Tellurium

CdTe quantum dots (QDs) were synthesized in aqueous solution using thioglycolic acid (TGA) as stabilizing agents. The interaction between TGA-CdTe QDs and fat mass and obesity-associated (FTO) protein was investigated by fluorescence, UV-visible absorption, synchronous fluorescence and three-dimensional fluorescence spectroscopy. Results revealed that TGA-CdTe QDs could strongly quench the intrinsic fluorescence of FTO protein with a static quenching procedure. Both the van der Waals and hydrogen bonding played a major role in stabilizing the complex. The binding constant and thermodynamic parameters at different temperatures were obtained. In addition, we found that the fluorescence intensity of QDs was significantly enhanced by the addition of FTO protein. Based on this, a sensitive method for detecting FTO protein was obtained in the linear range of 5.52×10(-9)-6.62×10(-7) mol L(-1) with the detection limit of 1.14×10(-9) mol L(-1). The influences of factors on the interaction between FTO protein and TGA-CdTe QDs were studied.

Topics: Cadmium Compounds; Calibration; Kinetics; Proteins; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Temperature; Thioglycolates; Time Factors

The application of fluorescent II-VI semiconductor quantum dots (QDs) as active photosensitizers in photodymanic inactivation (PDI) is still being evaluated. In the present study, we prepared 3 nm size CdTe QDs coated with mercaptosuccinic acid and conjugated them electrostatically with Zn(II) meso-tetrakis (N-ethyl-2-pyridinium-2-yl) porphyrin (ZnTE-2-PyP or ZnP), thus producing QDs-ZnP conjugates. We evaluated the capability of the systems, bare QDs and conjugates, to produce reactive oxygen species (ROS) and applied them in photodynamic inactivation in cultures of Candida albicans by irradiating the QDs and testing the hypothesis of a possible combined contribution of the PDI action. Tests of in vitro cytotoxicity and phototoxicity in fibroblasts were also performed in the presence and absence of light irradiation. The overall results showed an efficient ROS production for all tested systems and a low cytotoxicity (cell viability >90%) in the absence of radiation. Fibroblasts incubated with the QDs-ZnP and subjected to irradiation showed a higher cytotoxicity (cell viability <90%) depending on QD concentration compared to the bare groups. The PDI effects of bare CdTe QD on Candida albicans demonstrated a lower reduction of the cell viability (~1 log10) compared to bare ZnP which showed a high microbicidal activity (~3 log10) when photoactivated. The QD-ZnP conjugates also showed reduced photodynamic activity against C. albicans compared to bare ZnP and we suggest that the conjugation with QDs prevents the transmembrane cellular uptake of the ZnP molecules, reducing their photoactivity.

Topics: Cadmium Compounds; Candida albicans; Candidiasis; Cell Survival; Humans; Light; Metalloporphyrins; Photochemotherapy; Photosensitizing Agents; Quantum Dots; Tellurium

Nanoparticles (NPs) are increasingly being used in a number of applications that include biomedicine, biological labeling and cancer marker targeting, and their successful storage is important to preserve their viability. A systematic investigation of the thermal and photo stability of chemically stabilized cadmium telluride (CdTe) quantum dots (QDs) under various storage conditions either in solution or as dried nanoparticles has not been published. Here we report experiments involving chemically synthesized glutathione-capped CdTe QDs whose photoluminescence spectra were examined initially and then periodically during storage times up to 76 days.. Samples of dried QDs or QDs in solution (water or buffered) were examined under different light conditions including complete darkness, constant 12,000 lux incident light, and under diurnal sunlight; at temperatures ranging from -80 °C to room temperature.. Though QDs stored in solution in the dark at -80 °C lost only 50% of peak fluorescence (FL510) within 2 weeks, solution-stored QDs exposed to sunlight at room temperature showed FL510 drops of 85% in the first 24 hours. In contrast, QDs precipitated from aqueous solution, dried and stored in time course experiments in the presence of atmospheric oxygen--when resuspended in water--lost an average of only 12% FL510 over 76 days under all conditions tested, even in direct sunlight.. Glutathione-capped CdTe particles can be stored as dried nanoparticles for extended periods of time, enhancing their viability in biomedicine, biological labeling and cancer marker targeting.

Topics: Cadmium Compounds; Drug Stability; Glutathione; Nanoparticles; Oxidation-Reduction; Photochemical Processes; Quantum Dots; Sulfhydryl Compounds; Tellurium

A facile strategy was developed to prepare mesoporous structured ratiometric fluorescence molecularly imprinted sensor for highly sensitive and selective determination of melamine using CdTe QDs as target sensitive dye and hematoporphyrin as reference dyes. One-pot synthesis method was employed because it could simplify the imprinting process and shorten the experimental period. The as-prepared fluorescence MIPs sensor, which combined ratiometric fluorescence technique with mesoporous silica materials into one system, exhibited excellent selectivity and sensitivity. Under optimum conditions, these mesoporous structured ratiometric fluorescence MIP@QDs sensors showed detection limit as low as 38 nM, which was much lower than those non-mesoporous one. The recycling process was sustainable at least 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of melamine in raw milk and milk powder samples with satisfactory recoveries of 92-101%. The developed method proposed in this work proved to be a convenient, rapid, reliable and practical way to prepared high sensitive and selective fluorescence sensors with potentially applicable for trace pollutants analysis in complicated samples.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Chemistry Techniques, Synthetic; Fluorescent Dyes; Food Contamination; Hematoporphyrins; Milk; Molecular Imprinting; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium; Triazines

An amplified solid-state electrochemiluminescence (ECL) biosensor for detection of cholesterol in near-infrared (NIR) range was constructed based on CdTe quantum dots (QDs) decorated multiwalled carbon nanotubes@reduced graphene nanoribbons (CdTe-MWCNTs@rGONRs), which were prepared by electrostatic interactions. The CdTe QDs decorated on the MWCNTs@rGONRs resulted in the amplified ECL intensity by ~4.5 fold and decreased onset potential by ~100 mV. By immobilization of the cholesterol oxidase (ChOx) and NIR CdTe-MWCNTs@rGONRs on the electrode surface, a solid-state ECL biosensor for cholesterol detection was constructed. When cholesterol was added to the detection solution, the immobilized ChOx catalyzed the oxidation of cholesterol to generate H2O2, which could be used as the co-reactant in the ECL system of CdTe-MWCNTs@rGONRs. The as-prepared biosensor exhibited good performance for cholesterol detection including good reproducibility, selectivity, and acceptable linear range from 1 μM to 1mM with a relative low detection limit of 0.33 μM (S/N=3). The biosensor was successfully applied to the determination of cholesterol in biological fluid and food sample, which would open a new possibility for development of solid-state ECL biosensors with NIR emitters.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Cholesterol; Dielectric Spectroscopy; Electrochemical Techniques; Food Analysis; Graphite; Humans; Limit of Detection; Luminescent Measurements; Milk; Nanocomposites; Nanotubes, Carbon; Quantum Dots; Reproducibility of Results; Tellurium

It was reported that Proprotein convertase subtilisin/kexin type 6 (PCSK6) can promote the progression of rheumatoid arthritis to a higher aggressive status. In this work, a novel visible light induced photoelectrochemical (PEC) platform was designed to detect PCSK6 gene. ZnO@CdTe nanocable arrays/carboxylated g-C3N4 used as the PEC signal generator. Hexagonal ZnO nanorods grew on ITO electrode firstly. CdTe were then electrodeposited on the ZnO nanorods surface to enhance the photogenerated h(+)/e(-) separation efficiency. Carboxylated g-C3N4 was utilized to improve h(+)/e(-) separation efficiency and anchor the capture probes of PCSK6 gene by the covalent bonding effect. The 5' and 3' primers captured PCSK6 ssDNA by the specific recognition. The linear range was 10 pg/mL to 20.0 ng/mL with a detection limit of 2 pg/mL.

Topics: Arthritis, Rheumatoid; Biosensing Techniques; Cadmium Compounds; DNA Primers; DNA, Single-Stranded; Electrochemical Techniques; Electrodes; Graphite; Humans; Light; Nanostructures; Nitriles; Proprotein Convertases; Serine Endopeptidases; Tellurium; Zinc Oxide

We investigate the improvement from the use of high-Z CdTe sensors for pre-clinical K-edge imaging with the hybrid pixel detectors XPAD3. We compare XPAD3 chips bump bonded to Si or CdTe sensors in identical experimental conditions. Image performance for narrow energy bin acquisitions and contrast-to-noise ratios of K-edge images are presented and compared. CdTe sensors achieve signal-to-noise ratios at least three times higher than Si sensors within narrow energy bins, thanks to their much higher detection efficiency. Nevertheless Si sensors provide better contrast-to-noise ratios in K-edge imaging when working at equivalent counting statistics, due to their better estimation of the attenuation coefficient of the contrast agent. Results are compared to simulated data in the case of the XPAD3/Si detector. Good agreement is observed when including charge sharing between pixels, which have a strong impact on contrast-to-noise ratios in K-edge images.

Topics: Algorithms; Biosensing Techniques; Cadmium Compounds; Humans; Image Processing, Computer-Assisted; Phantoms, Imaging; Photons; Radiographic Image Interpretation, Computer-Assisted; Signal-To-Noise Ratio; Silicon; Tellurium; Tomography, X-Ray Computed

A simple protocol that can be used to simultaneously determinate enantiomers is extremely intriguing and useful. In this study, we proposed a low-cost, facile, sensitive method for simultaneous determination. The molecular recognition of Cu(2+) functionalized N-acetyl-l-cysteine capped CdTe quantum dots (Cu(2+)-NALC/CdTe QDs) with phenylalanine (PA) enantiomers was investigated based on the resonance Rayleigh scattering (RRS) spectral technique. The RRS intensity of NALC/CdTe QDs is very weak, but Cu(2+) functionalized NALC/CdTe QDs have extremely high RRS intensity, the most important observations are that PA could quench the RRS intensity of Cu(2+)-NALC/CdTe QDs, and that l-PA and d-PA have different degree of influence. In addition, those experimental factors such as acidity, concentration of Cu(2+) and reaction time were investigated in regards to their effects on enantioselective interaction. Finally, the applicability of the chiral recognized sensor for the analysis of chiral mixtures on enantiomers has been demonstrated, and the results that were obtained high precision (<4.63%) and low error (<3.06%).

Topics: Acetylcysteine; Cadmium Compounds; Copper; Phenylalanine; Quantum Dots; Scattering, Radiation; Spectrometry, Fluorescence; Stereoisomerism; Tellurium

Even though various strategies have reported for DNA detection, development of a simple, time-saving and specific fluorescent sensing platform still remains a desired goal. In this work, a quantum dots (QDs) based fluorescent reversible "off-on" mode was developed for sensitively recognition of herring sperm DNA (hsDNA). Firstly, in the "turn off" stage, the fluorescence of glutathione (GSH) capped CdTe QDs could be effectively quenched by ytterbium ion (Yb(3+)) was due to the occurrence of the electron transfer between Yb(3+) and the photoexcited QDs. And then, in the following "turn on" stage, with the effective binding reaction of Yb(3+) to hsDNA, the fluorescence intensity of GSH-capped CdTe QDs enhanced. Under the optimal conditions, the linear range of fluorescence versus the concentration of hsDNA was 0.010-12 μg/mL, and the detection limit was 3.033 ng/mL. In addition, the reaction mechanism among GSH-capped CdTe QDs, Yb(3+) and hsDNA were investigated by fluorescence spectroscopy, UV-vis spectrophotometry, fluorescence lifetime measurement and viscosity measurements. This analytical fluorescent reversible "off-on" pattern offered a way with good sensitivity and selectivity for the detection of hsDNA.

Topics: Cadmium Compounds; DNA; Fluorescence; Humans; Male; Molecular Conformation; Particle Size; Quantum Dots; Spermatozoa; Surface Properties; Tellurium; Ytterbium

New methods of analysis involving semiconductor nanocrystals (quantum dots [QDs]) as fluorescent probes have been highlighted in life science. QDs present some advantages when compared to organic dyes, such as size-tunable emission spectra, broad absorption bands, and principally exceptional resistance to photobleaching. Methods applying QDs can be simple, not laborious, and can present high sensibility, allowing biomolecule identification and quantification with high specificity. In this context, the aim of this work was to apply dual-color CdTe QDs to quantify red blood cell (RBC) antigen expression on cell surface by flow cytometric analysis. QDs were conjugated to anti-A or anti-B monoclonal antibodies, as well as to the anti-H (Ulex europaeus I) lectin, to investigate RBCs of A1, B, A1B, O, A2, and Aweak donors. Bioconjugates were capable of distinguishing the different expressions of RBC antigens, both by labeling efficiency and by flow cytometry histogram profile. Furthermore, results showed that RBCs from Aweak donors present fewer amounts of A antigens and higher amounts of H, when compared to A1 RBCs. In the A group, the amount of A antigens decreased as A1 > A3 > AX = Ael, while H antigens were AX = Ael > A1. Bioconjugates presented stability and remained active for at least 6 months. In conclusion, this methodology with high sensibility and specificity can be applied to study a variety of RBC antigens, and, as a quantitative tool, can help in achieving a better comprehension of the antigen expression patterns on RBC membranes.

Topics: Antibodies, Monoclonal; Blood Group Antigens; Cadmium Compounds; Erythrocytes; Flow Cytometry; Humans; Quantum Dots; Tellurium

Quantum dots (QDs) are engineered semiconductor nanocrystals with promising application in biomedicine, which have potential toxic effect on biomacromolecules by direct interaction and indirect impact in the body. In this work, the effect of N-acetyl-L-cysteine-capped CdTe quantum dots with fluorescence emission peak at 612 nm (QDs-612) on copper-zinc superoxide dismutase (Cu/ZnSOD) at molecular and cellular level was investigated using isothermal titration calorimetry, spectroscopic techniques, cell counting kit-8, and total SOD assay. The hydrophobic interaction between Cu/ZnSOD and QDs-612 caused static fluorescence quenching of the protein, which was spontaneous with binding constant calculated to be 3.28 × 10(5) L mol(-1). The microenvironment of tyrosine residues, skeleton, and secondary structure of Cu/ZnSOD were changed with adding QDs-612. The molecular Cu/ZnSOD activity was inhibited at different concentrations of QDs-612 as well as the intracellular Cu/ZnSOD activity after 2-h exposure. Compared with the cell viability of hepatocytes and nephrocytes (decreased markedly of the initial level) with higher concentrations of QDs-612 in the absence of vitamin C, the cell viability of these two primary cells increased in the presence of vitamin C, indicating the oxidative damage induced by QDs-612. Therefore, the inhibition of Cu/ZnSOD activity in these two primary cells may be caused by the oxidative damage of massive ROS or direct interaction with QDs-612. This work establishes a new approach to investigate the biological toxicity of CdTe QDs to biomacromolecule from both molecular and cellular perspectives and obtains experimental evidence to thoroughly study the toxicity of CdTe QDs in vivo.

Topics: Acetylcysteine; Animals; Cadmium Compounds; Cells, Cultured; Hepatocytes; Kidney; Mice; Oxidative Stress; Quantum Dots; Superoxide Dismutase; Tellurium

Although only a handful of organic materials have shown polariton condensation, their study is rapidly becoming more accessible. The spontaneous appearance of long-range spatial coherence is often recognized as a defining feature of such condensates. In this Letter, we study the emergence of spatial coherence in an organic microcavity and demonstrate a number of unique features stemming from the peculiarities of this material set. Despite its disordered nature, we find that correlations extend over the entire spot size, and we measure g(1)(r,r') values of nearly unity at short distances and of 50% for points separated by nearly 10  μm . We show that for large spots, strong shot-to-shot fluctuations emerge as varying phase gradients and defects, including the spontaneous formation of vortices. These are consistent with the presence of modulation instabilities. Furthermore, we find that measurements with flat-top spots are significantly influenced by disorder and can, in some cases, lead to the formation of mutually incoherent localized condensates.

Topics: Cadmium Compounds; Electromagnetic Phenomena; Interferometry; Lasers; Models, Theoretical; Optics and Photonics; Photons; Tellurium

We investigate the effects of the excitation power on the photoluminescence spectra of aqueous CdTe/CdS core-shell quantum dots. We have focused our efforts on nanoparticles that are drop-cast on a silicon nitride substrate and dried out. Under such conditions, the emission intensity of these nanocrystals decreases exponentially and the emission center wavelength shifts with the time under laser excitation, displaying a behavior that depends on the excitation power. In the low-power regime a blueshift occurs, which we attribute to photo-oxidation of the quantum dot core. The blueshift can be suppressed by performing the measurements in a nitrogen atmosphere. Under high-power excitation the nanoparticles thermally expand and aggregate, and a transition to a redshift regime is then observed in the photoluminescence spectra. No spectral changes are observed for nanocrystals dispersed in the solvent. Our results show a procedure that can be used to determine the optimal conditions for the use of a given set of colloidal quantum dots as light emitters for photonic crystal optical cavities.

Topics: Cadmium Compounds; Light; Luminescent Measurements; Quantum Dots; Sulfides; Tellurium; Water

In this work, a novel sensor technology based on CdTe detectors was tested for prompt gamma and neutron detection using boronated targets in (epi)thermal neutron beam at FiR1 research reactor in Espoo, Finland. Dedicated neutron filter structures were omitted to enable simultaneous measurement of both gamma and neutron radiation at low reactor power (2.5 kW). Spectra were collected and analyzed in four different setups in order to study the feasibility of the detector to measure 478 keV prompt gamma photons released from the neutron capture reaction of boron-10. The detector proved to have the required sensitivity to detect and separate the signals from both boron neutron and cadmium neutron capture reactions, which makes it a promising candidate for monitoring the spatial and temporal development of in vivo boron distribution in boron neutron capture therapy.

Topics: Boron Neutron Capture Therapy; Cadmium Compounds; Calibration; Gamma Rays; Neutrons; Tellurium

The identification of subtypes of known tumor markers is of great importance for clinical diagnosis but still a great challenge in novel detection methodologies with simple operation and acceptable sensitivity. This work for the first time reported a quantum dots (QDs) based potential-resolved electrochemiluminescent (ECL) immunosensor to realize simultaneous detection of dual targets. Because of different surface microstructures, dimercaptosuccinic acid stabilized CdTe (DMSA-CdTe) QDs and TiO2 nanoparticles-glutathione stabilized CdTe (TiO2-GSH-CdTe) QDs composites showed a large difference of ECL peak potential (∼360 mV), which provided an access for potential-resolution detection. The ECL emission on indium tin oxide electrodes showed consistent strength during the cyclic scan, and intensity data were collected at -0.89 V and -1.25 V (vs Ag/AgCl) for DMSA-CdTe QDs and TiO2-GSH-CdTe QDs composites, respectively. The interface modification procedures of immunosensor construction were characterized by atomic force microscopy. The portion of Lens culinaris lectin affiliated isoform of alpha fetoprotein (AFP), AFP-L3%, in total AFP, is recently a novel criteria showing even higher sensitivity and specificity than AFP at the early stage of cancer. Combined with the enzyme cyclic amplification strategy, linear ranges for AFP-L3 and AFP dual-targets detection were 3.24 pg mL(-1)-32.4 ng mL(-1) and 1.0 pg mL(-1)-20 ng mL(-1), with limits of detection of 3.24 pg mL(-1) and 1.0 pg mL(-1), respectively. Compared with clinical detection data, the calculated portion of AFP-L3% by as-prepared immunosensor showed acceptable accuracy. These results open a new avenue for facile and rapid multiple-components detection based on the nano-ECL technique and provide a new clinical diagnosis platform for HCC.

Topics: alpha-Fetoproteins; Antibodies, Immobilized; Biomarkers, Tumor; Biosensing Techniques; Blood Chemical Analysis; Cadmium Compounds; Electrochemistry; Electrodes; Glutathione; Humans; Immunoassay; Limit of Detection; Luminescent Measurements; Protein Isoforms; Quantum Dots; Reproducibility of Results; Tellurium; Titanium

To investigate whether bone mineral density can be evaluated more accurately using a panoramic device with a new cadmium telluride photon-counting sensor and software than 2 panoramic devices with a conventional semiconductor sensor.. A fiduciary test object with several known levels of hydroxy apatite mineral concentration was placed in a phantom on the mandibular occlusal plane. Panoramic images were acquired by changing the position of the test object within the dental arch. The gray value, the spectrum deformation index (SDI), and the relative attenuation index (RAI) of the test object were evaluated. The SDI and RAI represent unique energy information as acquired by the QR-Master panoramic machine and the corresponding special QR-MC analysis software. In order to compare the values expressed in the different units (gray, SDI, and RAI values), the percentage discrepancy was calculated.. The cadmium telluride photon-counting fitted machine more consistently separated each of the hydroxy apatite concentrations in all of the different positioning configurations and locations. The SDI function of the QR Master machine produced more stable values than the RAI value and the gray values of the 2 conventional panoramic machines.. The methodologies as developed for this study can be used to test more sophisticated analyses for the determination of bone density.

Topics: Bone Density; Cadmium Compounds; Durapatite; Fiducial Markers; Humans; Phantoms, Imaging; Photons; Quantum Dots; Radiographic Image Interpretation, Computer-Assisted; Radiography, Panoramic; Software; Tellurium

A novel dual-photoluminescence probe for Cu(2+) has been developed, in which the graphene quantum dots with blue emission and CdTe QDs with yellow emission act as internal standard and probe, respectively. The photoluminescence probe exhibited selective sensing for Cu(2+) with a limit of detection (3SD/k) of 5.3 × 10(-8) M and showed its potential application in visual imaging. The results indicated that the constructed probe can be employed for sensing Cu(2+) by the naked eye, and also for monitoring intracellular Cu(2+).

Topics: Cadmium Compounds; Cell Line, Tumor; Color; Copper; Fluorescent Dyes; Graphite; Humans; Quantum Dots; Tellurium

This paper reports a quantum dot (QD)-based "off-on" fluorescent biosensor specifically for the determination of glutathione (GSH) with high sensitivity. The biosensor was based on the following two properties. Firstly, the high fluorescence of N-acetyl-L-cysteine (NALC) capped CdTe QDs could be effectively quenched by Hg(2+) due to the binding of Hg(2+) to the NALC on the surface of the QDs and the electron transfer from the photoexcited NALC-capped CdTe QDs to Hg(2+). Secondly, in the presence of GSH, the fluorescence intensity of NALC-capped CdTe QDs was found to be efficiently recovered. Under some optimized conditions, the relatively restored fluorescence intensity was proportional to the concentration of GSH in the range of 4-64 μg mL(-1), with a correlation coefficient of 0.9980 and a limit of detection of 2.49 ng mL(-1). In addition, the established method shows a high selectivity for some amino acids except cysteine. Moreover, to further investigate its performance, the biosensor was applied to the determination of GSH in human serum samples through a standard addition method and determination of normal GSH concentration in original human serum samples with satisfactory results.

Topics: Acetylcysteine; Biosensing Techniques; Cadmium Compounds; Electron Transport; Glutathione; Humans; Hydrogen-Ion Concentration; Kinetics; Quantum Dots; Sodium Chloride; Spectrometry, Fluorescence; Tellurium

Autophagy is a highly important intracellular process for the degradation of endogenous or foreign contents in the cytoplasm. Though nanomaterials-induced autophagy has been extensively studied, real-time information about the autophagic process induced by nanomaterials in live organisms remains unknown. Here by using Caenorhabditis elegans as the model organism and fluorescent semiconductor quantum dots (QDs) as a representative nanomaterial, we systematically investigated the phenomenon of QDs-induced autophagy in live organisms. Our results demonstrated that the internalized QDs trigger a complete autophagic process in C. elegans intestinal cells. Further investigations revealed that this QD-induced autophagy in C. elegans is neither a response to released heavy metal ions by the QDs, nor an attempt to engulf exogenous QD materials, but a defensive strategy of the organism to clear and recycle damaged endosomes. Of particular significance, for the first time, we presented real-time tracking of autophagosomes formation in live organisms, providing detailed temporal-spatial information of this process. This study may help us better understand the relationship between nanomaterials and autophagy in vivo, and provide invaluable information for safety evaluation and bio-application of nanomaterials.

Topics: Animals; Autophagy; Cadmium Compounds; Caenorhabditis elegans; Computer Systems; Endocytosis; Endosomes; Intestines; Phagosomes; Quantum Dots; Subcellular Fractions; Tellurium

A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

Topics: Adsorption; Cadmium Compounds; Energy Transfer; Luminescent Measurements; Materials Testing; Nanocomposites; Phase Transition; Quantum Dots; Silicon Dioxide; Surface Properties; Tellurium

The toxicity of quantum dots (QDs) has been extensively studied over the past decade. Some common factors that originate the QD toxicity include releasing of heavy metal ions from degraded QDs and the generation of reactive oxygen species on the QD surface. In addition to these factors, we should also carefully examine other potential QD toxicity causes that will play crucial roles in impacting the overall biological system. In this contribution, we have performed cytotoxicity assessment of four types of QD formulations in two different human cancer cell models. The four types of QD formulations, namely, mercaptopropionic acid modified CdSe/CdS/ZnS QDs (CdSe-MPA), PEGylated phospholipid encapsulated CdSe/CdS/ZnS QDs (CdSe-Phos), PEGylated phospholipid encapsulated InP/ZnS QDs (InP-Phos) and Pluronic F127 encapsulated CdTe/ZnS QDs (CdTe-F127), are representatives for the commonly used QD formulations in biomedical applications. Both the core materials and the surface modifications have been taken into consideration as the key factors for the cytotoxicity assessment. Through side-by-side comparison and careful evaluations, we have found that the toxicity of QDs does not solely depend on a single factor in initiating the toxicity in biological system but rather it depends on a combination of elements from the particle formulations. More importantly, our toxicity assessment shows different cytotoxicity trend for all the prepared formulations tested on gastric adenocarcinoma (BGC-823) and neuroblastoma (SH-SY5Y) cell lines. We have further proposed that the cellular uptake of these nanocrystals plays an important role in determining the final faith of the toxicity impact of the formulation. The result here suggests that the toxicity of QDs is rather complex and it cannot be generalized under a few assumptions reported previously. We suggest that one have to evaluate the QD toxicity on a case to case basis and this indicates that standard procedures and comprehensive protocols are urgently needed to be developed and employed for fully assessing and understanding the origins of the toxicity arising from different QD formulations.

Topics: Apoptosis; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Humans; Indium; Neoplasms, Experimental; Phosphines; Quantum Dots; Selenium Compounds; Tellurium; Toxicity Tests

The photoluminescence (PL) quenching of thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) by glutathione (GSH)-capped Au nanocrystals (NCs) were investigated via PL degradated measurement. It was found that the PL of the QDs with several sizes can be effectively quenched by GSH-Au NCs. The size and PL peak wavelengths of QDs have no significant impact on the quenching processing. Through the characterizations of UV-visble absorption spectrum, Zeta potential and steady-state, and time-resolved fluorescence spectroscopy, it was proved that the PL quenching of the QDs by GSH-Au NCs was attributed to static quenching caused by the formation of a QDs-Au complex. The binding parameters calculated from modified Stern-Volmer equation showed that the binding affinities between the GSH-Au NCs and CdTe QDs was in the order of 10(5) L x mol(-1), which indicated that the binding force was larger and the effective quenching occurred. The thermodynamic parameters studies revealed that the binding was characterized by positive enthalpy and positive entropy changes and hydrophobic force played a major role for QDs-Au association. In addition, all the quenching experiments were conducted in the phosphate-buffered saline (PBS) buffer solution at pH 7.4 and the investigation is expected to be applied in the biology.

Topics: Cadmium Compounds; Glutathione; Hydrophobic and Hydrophilic Interactions; Nanoparticles; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A series of red to near-infrared (NIR) emitting quantum dots (QDs) with spherical morphologies and tunable photoluminescence (PL) properties have been synthesized by a facile organic route using octadecene (ODE) as solvent and oleic acid (OA) as single capping agent. CdSe cores with the average size of 4.5 nm display the typical optical behaviors with the PL emission peak around 610 nm. The coating CdZnS shells are introduced on the surface of CdSe cores for improving the photostability and PL efficiency of the initial QDs. As the thickness of CdZnS shells increasing, the gradual red-shift of emission wavelength varying from 617 to 634 nm of the resulting QDs can be observed, along with the remarkable increase of PL quantum yield (QY). The composition-dependent CdTe(x)Se(1-x) (CdTeSe) cores with the emission in NIR region are easily carried out by adjusting the molar ratio of Se/Te. The abnormal variation of optical bowling effect is mainly ascribed to the composition effect of alloyed QDs. Compared with CdTe0.1Se0.9/CdZnS core/shell QDs, the introducing of CdZnS shells on CdTe0.05Se0.95 cores can exhibit better passivation effect on surface status, consequently leading to the red-shifted emission peaks in the range of 739-752 nm with the maximum PL QY reaching up to 45.09%. The unique PL properties of CdTeSe-based QDs in the red to NIR range make these core/shell QDs attractive for future biological sensing and labeling applications.

Topics: Cadmium Compounds; Luminescent Agents; Quantum Dots; Selenium; Spectroscopy, Near-Infrared; Tellurium; Zinc

CdTe quantum dots (QDs) were synthesized by 3-mercaptopropionic acid (MPA) and thioglycollic acid (TGA) as capping agents. It is confirmed that TGA and MPA molecules were attached on the surface of the QDs using Fourier transform infrared (FT-IR) spectra. The movement of the QDs in agarose gel electrophoresis indicated that MPA-capped CdTe QDs had small hydrodynamic diameter. The photoluminescence (PL) intensity of TGA-capped QDs is higher than that of MPA-capped QDs at same QD concentration because of the surface passivation of TGA. To systemically investigate the photodegradation, CdTe QDs with various PL peak wavelengths were dispersed in phosphate buffered saline (PBS) and Tris-borate-ethylenediaminetetraacetic acid (TBE) buffer solutions. It was found that the PL intensity of the QDs in PBS decreased with time. The PL peak wavelengths of the QDs in PBS solutions remained unchanged. As for TGA-capped CdTe QDs, the results of PL peak wavelengths in TBE buffer solutions indicated that S(2-) released by TGA attached to Cd(2+) and formed CdS-like clusters layer on the surface of aqueous CdTe QDs. In addition, the number of TGA on the CdTe QDs surface was more than that of MPA. When the QDs were added to buffer solutions, agents were removed from the surface of CdTe QDs, which decreased the passivation of agents thus resulted in photodegradation of CdTe QDs in buffer solutions.

Topics: 3-Mercaptopropionic Acid; Buffers; Cadmium Compounds; Photolysis; Quantum Dots; Spectrum Analysis; Tellurium; Thioglycolates

To impart biocompatibility, stability, and specificity to quantum dots (QDs)-and to reduce their toxicity-it is essential to carry out surface modification. However, most surface-modification processes are costly, complicated, and time-consuming. In addition, the modified QDs often have a large size, which leads to easy aggregation in biological environments, making it difficult to excrete them from in vivo systems. To solve these problems, three kinds of conventional polymers, namely, polyvinyl alcohol (PVA, neutral), sodium polystyrene sulfonate (PSS, negative charged), and poly(diallyl dimethyl ammonium chloride) (PDDA, positive charged) were selected to modify the surface of QDs at low cost via a simple process in which the size of the QDs was kept small after modification. The effect of polymer modification on the photoluminescence (PL) properties of the QDs was systematically investigated. High quantum yields (QYs) of 65 % were reached, which is important for the realization of bio-imaging. Then, the cytotoxicity of CdTe QD-polymer composites was systematically investigated via MTT assay using the Cal27 and HeLa cell lines, especially for high concentrations of QD-polymer composites in vitro. The experimental results showed that the cytotoxicity decreased in the order CdTe-PDDA>CdTe>CdTe-PSS>CdTe-PVA, indicating that PSS and PVA can reduce the toxicity of the QDs. An obvious cytotoxicity of CdTe-PVA and CdTe-PSS was present until 120 h for the Cal27 cell line and until 168 h for the HeLa cell line. At last, the Cal27 cell line was selected to realize bio-imaging using CdTe-PSS and CdTe-PVA composites with different emission colors under one excitation wavelength.

Topics: Cadmium Compounds; Cell Line, Tumor; HeLa Cells; Humans; Luminescence; Molecular Imaging; Molecular Structure; Particle Size; Photochemical Processes; Polymers; Quantum Dots; Surface Properties; Tellurium

A color change observable by the naked eye to indicate the content of an analyte is considered to be the most conceivable way of various sensing protocols. By taking advantage of the Förster resonance energy transfer (FRET) principles, we herein designed a dual-emission ratiometric fluorescent aptasensor for ochratoxin A (OTA) detection via a dual mode of fluorescent sensing and onsite visual screening. Amino group-modified OTA's aptamer was firstly labeled with the green-emitting CdTe quantum dots (gQDs) donor. The red-emitting CdTe QDs (rQDs) which were wrapped in the silica sphere could serve as the reference signal, while the gold nanoparticle (AuNP) acceptors were attached on the silica surface to bind with the thiolated complementary DNA (cDNA). The hybridization reaction between the aptamer and the cDNA brought gQD-AuNP pair close enough, thereby making the FRET occur in the aptasensor fabrication, while the subsequent fluorescence recovery induced by OTA was obtained in the detection procedure. Based on the red background of the wrapped rQDs, the aptasensor in response to increasing OTA displayed a distinguishable color change from red to yellow-green, which could be conveniently readout in solution even by the naked eye. Since the bioconjugations used as the aptasensor can be produced at large scale, this method can be used for in situ, rapid, or high-throughput OTA detection after only an incubation step in a homogeneous mode. We believe that this novel aptasensing strategy provides not only a promising method for OTA detection but also a universal model for detecting diverse targets by changing the corresponding aptamer.

Topics: Aptamers, Nucleotide; Cadmium Compounds; Color; Colorimetry; DNA, Complementary; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Food Analysis; Food Contamination; Gold; Metal Nanoparticles; Microscopy, Electron, Transmission; Nucleic Acid Hybridization; Ochratoxins; Quantum Dots; Reproducibility of Results; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium; Wine

With the applications of quantum dots (QDs) expanding, many studies have described the potential adverse effects of QDs, yet little attention has been paid to potential toxicity of QDs in the liver. The aim of this study was to investigate the effects of cadmium telluride (CdTe) QDs in mice and murine hepatoma cells alpha mouse liver 12 (AML 12). CdTe QDs administration significantly increased the level of lipid peroxides marker malondialdehyde (MDA) in the livers of treated mice. Furthermore, CdTe QDs caused cytotoxicity in AML 12 cells in a dose- and time-dependent manner, which was likely mediated through the generation of reactive oxygen species (ROS) and the induction of apoptosis. An increase in ROS generation with a concomitant increase in the gene expression of the tumor suppressor gene p53, the pro-apoptotic gene Bcl-2 and a decrease in the anti-apoptosis gene Bax, suggested that a mitochondria mediated pathway was involved in CdTe QDs' induced apoptosis. Finally, we showed that NF-E2-related factor 2 (Nrf2) deficiency blocked induced oxidative stress to protect cells from injury induced by CdTe QDs. These findings provide insights into the regulatory mechanisms involved in the activation of Nrf2 signaling that confers protection against CdTe QDs-induced apoptosis in hepatocytes.

Topics: Animals; Apoptosis; Cadmium Compounds; Liver; Male; Malondialdehyde; Mice; NF-E2-Related Factor 2; Oxidative Stress; Quantum Dots; Reactive Oxygen Species; Signal Transduction; Tellurium

It is of great importance to develop novel and sensitive sensing materials for the detection of proteins and microorganisms to fulfill the demand of disease diagnosis. As the selectivity and sensitivity of sensing systems are highly dependent on the receptor, the fluorescent sensor array with imidazolium ionic liquids (ILs) and ionic liquid-quantum dots conjugates as semiselective receptors is developed for protein/bacteria differential sensing or discrimination. The IL sensing system formed by 1,3-dibutylimidazolium chloride (BBimCl), 1,3-diethylimidazolium bromine (EEimBr), 1,3-dibutylimidazolium bromine (BBimBr), 1,3-dihexylimidazolium bromine (HHimBr), and 1,3-dioctylimidazolium bromine (OOimBr) and the IL@QDs/QDs sensing system formed by CdTe, BBimCl@CdTe, EEimBr@CdTe, BBimBr@CdTe, and HHimBr@CdTe are tested, by transferring the interaction binding difference between receptors and proteins to the fluorescent response pattern. The IL sensing system is applied to the identification of 48 samples (8 proteins at 500 nM) with an accuracy of 91.7%. For the IL@QDs/QDs sensing system, 8 proteins are completely distinguished with 100% accuracy at a very low concentration level of 10 nM. Remarkably, 36 training cases (6 strains of bacteria from 3 different species) are discriminated with 100% (OD600 of 0.1).

Topics: Bacteria; Cadmium Compounds; Ionic Liquids; Proteins; Quantum Dots; Tellurium

Porcine reproductive and respiratory syndrome virus (PRRSV) has been a significant pathogen towards global swine industry upon its emergence in the late 1980s and since then has exemplified a rapidly evolving, widely spreading pathogen. It is urgently important to develop a simple, rapid and cost effective method to detect this pathogen when virus outbreaks. In the present work, it was found that virus antibody modified platinum nanotubes (Pt-Ab) could act as a superquencher to CdTe:Zn(2+) quantum dots (CdTe:Zn(2+) QDs) fluorescence by Stern-Volmer constants nearly 10(9) M(-1) without any aggregation, the CdTe:Zn(2+) QDs fluorescence will recover as the Pt-Ab goes away by antibody and antigen interaction when virus was added into the probe solution, releasing CdTe:Zn(2+) QDs from the surface of Pt-Ab. By the recovery fluorescence intensity, it can realize qualitative and quantitative detection of PRRSV. This method gives a fast response to PRRSV concentration and provides a sensitive detection limit (2.4 ng/mL). Moreover, it can be applied in infected porcine serum samples and obtain satisfied results.

Topics: Animals; Antibodies, Viral; Biosensing Techniques; Cadmium Compounds; Feasibility Studies; Immunoassay; Limit of Detection; Nanotubes; Platinum; Porcine respiratory and reproductive syndrome virus; Quantum Dots; Spectrometry, Fluorescence; Swine; Tellurium; Water; Zinc

In this study, some effort has been performed to provide low temperature, less time consuming and facile routes for the synthesis of CdTe quantum dots using ultrasound and water soluble capping agent thioglycolic acid. TGA-capped CdTe quantum dots were characterized through x-ray diffraction, transmission electron microscopy, Fourier transform infrared, ultraviolet-visible and fluorescence spectroscopy. The prepared quantum dots were used for warfarin determination based on the quenching of the fluorescence intensity in aqueous solution. Under the optimized conditions, the linear range of quantum dots fluorescence intensity versus the concentration of warfarin was 0.1-160.0 μM, with the correlation coefficient of 0.9996 and a limit of detection of 77.5 nM. There was no interference to coexisting foreign substances. The selectivity of the sensor was also tested and the results show that the developed method possesses a high selectivity for warfarin.

Topics: Blood Chemical Analysis; Buffers; Cadmium Compounds; Humans; Hydrogen-Ion Concentration; Limit of Detection; Osmolar Concentration; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thioglycolates; Ultrasonic Waves; Warfarin

Although it has been reported that fluorescent quantum dots (QDs) have obvious acute toxic effects in vitro, their toxic effects at low doses or threshold doses are still unknown. Therefore, we evaluated the biological histocompatibility and in vitro toxicity of three types of QDs at threshold doses. Also, we compared the toxic effects of QDs with different raw chemical compositions and sizes. The results showed that low concentrations of QDs (≤7 μg/mL) had no obvious effect on cell viability and cell membrane damage, oxidative damage, cell apoptosis or DNA damage. However, QD exposure led to a significant cytotoxicity at higher doses (≥14 μg/mL) and induced abnormal cellular morphology. In addition, when comparing the three types of QDs, 2.2 nm CdTe QDs exposure showed a significantly increased proportion of apoptotic cells and significant DNA damage, suggesting that size and composition contribute to the toxic effects of QDs. Based on these discussions, it was concluded that the concentration (7 μg/mL) may serve as a threshold level for these three types of QDs only in L929 fibroblasts, whereas high concentrations (above 14 μg/mL) may be toxic, resulting in inhibition of proliferation, induction of apoptosis and DNA damage in L929 fibroblasts.

Topics: Animals; Apoptosis; Cadmium Compounds; Cell Line; Cell Survival; DNA Damage; Fibroblasts; Hemolysis; Mice; Oxidative Stress; Particle Size; Quantum Dots; Selenium Compounds; Tellurium; Toxicity Tests

Quantum dots (QDs) have become one of the most promising luminescent materials for tracking viral infection in living cells. However, several issues regarding how QDs interact with the virus remain unresolved. Herein, the effects of Glutathione (GSH) capped CdTe QDs on virus were investigated by using pseudorabies virus (PRV) as a model. One-step growth curve and fluorescence colocalization analyses indicate that CdTe QDs inhibit PRV multiplication in the early stage of virus replication cycle by suppressing the invasion, but have no significant effect on the PRV penetration. Fluorescence spectrum analysis indicates that the size of QDs is reduced gradually after the addition of PRV within 30 min. Release of Cd(2+) was detected during the interaction of QDs and PRV, resulting in a decreased number of viruses which can infect cells. Further Raman spectra and Circular Dichroism (CD) spectroscopy analyses reveal that the structure of viral surface proteins is altered by CdTe QDs adsorbed on the virus surface, leading to the inhibition of virus replication. This study facilitates an in-depth understanding of the pathogenic mechanism of viruses and provides a basis for QDs-labeled virus research.

Topics: Animals; Cadmium Compounds; Cell Line; Glutathione; Herpesvirus 1, Suid; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Spectrum Analysis, Raman; Static Electricity; Swine; Tellurium; Viral Plaque Assay; Virus Replication

Aldo-ketoreductase family 1 member B10 (AKR1B10) is a novel prognostic predictor and therapeutic target for colorectal cancer (CRC), and enzyme-linked immunosorbent assays (ELISAs) and electrochemiluminescence (ELC) assays are sample-consuming and high-cost methods. Therefore, it is very necessary to develop a new, simple, and fast yet highly sensitive and specific method for the detection of AKR1B10 in serum. Semiconducting quantum dots (QDs) possess a high fluorescence quantum yield, stability against photobleaching, and size-controlled luminescence properties; thus, they are suitable for photoelectrochemical tumor marker detection, especially in complex biological samples. However, CdTe/CdS QDs have not been applied for the detection of AKR1B10 in serum.. AKR1B10 in peripheral blood has been established using anti-AKR1B10-conjugated CdTe/CdS QDs and measurements. The assay sensitivity was determined by measuring the quenched fluorescence intensity of AKR1B10 at 0.5, 1, 2, 5, or 10 ng/mL in phosphate-buffered solution (PBS) or 0.25%, 0.5%, 1.0%, 2.0%, or 5% human serum diluted in PBS. The assay was optimized under different pH values (7.00 - 7.40) for different reaction durations (10 - 60 minutes). The specificity of anti-AKR1B10-QDs was determined by testing the inhibition of AKR1B10 activity with carcinoembryonic antigen (CEA), immunoglobulin G (IgG), or alpha-fetoprotein (AFP), each at 1 ng/mL.. Under the optimized incubation time (30 minutes) at room temperature and optimal pH (7.1 - 7.2), a correlation between the decreased fluorescence intensity of anti-AKR1B10-conjugated CdTe/CdS QDs and the concentration of AKR1B10 in the range from 0.05 to 100 ng/mL was established. The assay was sensitive for the detection of AKR1B10 in the range from 0.05 to 100 ng/mL, and the detection limit was 0.02 ng/mL. The assay presented a high specificity because the anti-AKR1B10-conjugated CdTe/CdS QDs only reacted with AKR1B10 in the sera in the presence of CEA, IgG, or AFP.. In conclusion, the immunofluorescence assay to detect AKR1B10 in serum using anti-AKR1B10-conjugated CdTe/CdS QDs was simple and fast yet presented high sensitivity and specificity. Our findings provide a promising tool for the early prediction of CRC.

Topics: Aldehyde Reductase; Aldo-Keto Reductases; Cadmium Compounds; Fluorescent Antibody Technique; Humans; Quantum Dots; Sensitivity and Specificity; Sulfides; Tellurium

Water-soluble Zn-doped CdTe quantum dots (CdTe:Zn(2+) QDs) have attracted great attention in biological and biomedical applications. In particular, for any potential in vivo application, the interaction of CdTe:Zn(2+) QDs with human serum albumin (HSA) is of greatest importance. As a step toward the elucidation of the fate of CdTe:Zn(2+) QDs introduced to organism, the molecular interactions between CdTe:Zn(2+) QDs with three different sizes and HSA were systematically investigated by spectroscopic techniques. Three CdTe:Zn(2+) QDs with maximum emission of 514 nm (green QDs, GQDs), 578 nm (yellow QDs, YQDs), and 640 nm (red QDs, RQDs) were tested. The binding of CdTe:Zn(2+) QDs with HSA was a result of the formation of HSA-QDs complex and electrostatic interactions played major roles in stabilizing the complex. The Stern-Volmer quenching constant, associative binding constant, and corresponding thermodynamic parameters were calculated. The site-specific probe competitive experiments revealed that the binding location of CdTe:Zn(2+) QDs with HSA was around site I. The microenvironmental and conformational changes of HSA induced by CdTe:Zn(2+) QDs were analyzed. These results suggested that the conformational change of HSA was dramatically at secondary structure level and the biological activity of HSA was weakened in the present of CdTe:Zn(2+) QDs with bigger size.

Topics: Cadmium Compounds; Circular Dichroism; Humans; Quantum Dots; Serum Albumin; Spectrometry, Fluorescence; Tellurium; Zinc

Hypoxia is a characteristic of cancer and plays a key role in tumorigenesis, angiogenesis and resistance to cancer therapies. SiRNA treatment is effective against hypoxic tumors by gene silencing. However, siRNA delivery to the hypoxic regions of solid tumors still presents a challenge due to the distance from blood vessels and the increased presence of efflux transporters. Therefore, tumor therapies would be improved through the immediate development of an effective siRNA delivery system to hypoxic regions. To this end, we synthesized a system to deliver HIF-1α siRNA into hypoxic tumor cells. The system consists of a functional shell composed of 2-deoxyglucose (DG)-polyethylene glycol (PEG) connected with the compound of lipoic acid, lysine and 9-poly-d-arginine (LA-Lys-9R) by a hydrazone bond and a core of CdTe quantum dots (QDs). The molecular structure of DG-PEG-LA-Lys-9R was confirmed by liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The multifunctional CdTe QDs measured approximately 200 nm and showed excellent biocompatibility, perfect siRNA binding capability and enhanced hypoxic tumor targeting. Importantly, the system described here is pH-responsive with a hydrazone bond; therefore, it avoids GLUT1 receptor-mediated endocytic recycling, resulting in irreversible delivery of the siRNA. We used Western blots to confirm the superior gene silencing efficiency induced by the DG-PEG-LA-Lys-9R with hydrazone modified CdTe QDs. Here, we demonstrate high efficacy of the siRNA tumor delivery system using in vitro and in vivo experiments. In addition, these studies demonstrate that pH-responsive hybrid quantum dots show improved antitumor efficacy with decreased organ toxicity, indicating a promising siRNA delivery system for hypoxic cancer therapy.

Topics: Animals; Cadmium Compounds; Cell Hypoxia; Cell Survival; Deoxyglucose; Gene Expression Regulation, Neoplastic; Gene Transfer Techniques; Glucose Transporter Type 1; Hep G2 Cells; Humans; Hydrazones; Hydrogen-Ion Concentration; Hypoxia-Inducible Factor 1, alpha Subunit; Liver Neoplasms; Lysine; MCF-7 Cells; Mice, Inbred BALB C; Mice, Nude; Oxygen; Peptides; Polyethylene Glycols; Quantum Dots; RNA, Small Interfering; RNAi Therapeutics; Tellurium; Thioctic Acid; Time Factors; Tumor Burden; Tumor Microenvironment; Xenograft Model Antitumor Assays

A novel flow-injection chemiluminescence (FI-CL) method was described for the determination of sinomenine hydrochloride (SIN). The method was based on the inhibitory effect of SIN on the CL reaction of luminol and K3Fe(CN)6 in an alkaline solution, which was sensitized by CdTe/CdS quantum dots (QDs). Under the optimized conditions, the linear range for the determination of SIN was 1.0 × 10(-8) to 1.4 × 10(-6) mol/L. The detection limit was 7.5 × 10(-9) mol/L, and the relative standard deviation was 2.47% (n = 11). The current CL method was applied to determine SIN in pharmaceutical formulations and biological fluids with satisfactory results. The possible CL reaction mechanism was discussed briefly.

Topics: Cadmium Compounds; Ferricyanides; Flow Injection Analysis; Kinetics; Limit of Detection; Luminescent Measurements; Luminol; Morphinans; Quantum Dots; Sulfides; Tellurium

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

Topics: Cadmium Compounds; Catalysis; Chlorophenols; Nanocomposites; Photolysis; Tellurium; Titanium; Ultraviolet Rays

Water-soluble glutathione (GSH)-capped core/shell CdTe/CdS quantum dots (QDs) were synthesized. In pH5.4 sodium phosphate buffer medium, the interaction between GSH-CdTe/CdS QDs and sanguinarine (SA) was investigated by spectroscopic methods, including fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy. Addition of SA to GSH-CdTe/CdS QDs results in fluorescence quenching of GSH-CdTe/CdS QDs. Quenching intensity was in proportion to the concentration of SA in a certain range. Investigation of the quenching mechanism, proved that the fluorescence quenching of GSH-CdTe/CdS QDs by SA is a result of electron transfer. Based on the quenching of the fluorescence of GSH-CdTe/CdS QDs by SA, a novel, simple, rapid and specific method for SA determination was proposed. The detection limit for SA was 3.4 ng/mL and the quantitative determination range was 0.2-40.0 µg/mL with a correlation coefficient of 0.9988. The method has been applied to the determination of SA in synthetic samples and fresh urine samples of healthy human with satisfactory results.

Topics: Benzophenanthridines; Cadmium Compounds; Fluorescence; Glutathione; Isoquinolines; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Sulfates; Tellurium

Herein, we synthesized a novel core-satellite CdTe/Silica/Au NCs hybrid sphere by covalently linking the separately synthesized highly fluorescent bovine serum albumin (BSA) stabilized gold nanoclusters (Au@BSA NCs) to the surface of the amino functionalized CdTe@SiO2 spheres by using the EDC chemistry. Numerous "satellites" of Au NCs were linked on the surface of the CdTe@SiO2 by the way of amide bonding. The synthesized dual-emission hybrid spheres were further characterized by the transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), UV-vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL), etc. Finally, the CdTe/Silica/Au NCs hybrid spheres were developed as ratiometric fluorescence probe for the determination of Cu(2+) with high sensitivity and selectivity. The fluorescence intensity ratio (F545 nm/F655 nm) of the probe against the concentration of Cu(2+) showed a good linear relationship from 6.0×10(-7) mol L(-1) to 100.0×10(-7) mol L(-1). It showed an excellent reproducibility (0.67% relative standard deviation for 10 replicate measurements of Cu(2+) at 40.0×10(-7) mol L(-1)) and low detection limit (4.1×10(-7) mol L(-1)). Furthermore, the ratiometric fluorescent probe was successfully applied in the determination of Cu(2+) in vegetable samples with satisfactory results.

Topics: Biosensing Techniques; Cadmium Compounds; Cations, Divalent; Copper; Fluorescent Dyes; Gold; Limit of Detection; Nanostructures; Reproducibility of Results; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium; Vegetables

Purification is a separated post-treatment step after the synthesis of nanocrystals (NCs) in order to exclude excess ligands and monomers in NC solution. The common purification process involves many manipulations, such as concentrating, addition of anti-solvents and centrifugation, which are troublesome and time consuming. In this work, we originally integrate NC synthesis and NC purification in one-pot via selecting water-ethanol co-environment for NC synthesis and NC purification. Our research shows that NCs can grow in water-ethanol mixture. When growing into critical size, NCs will automatically precipitate from the solution. Element analysis demonstrates that precipitates fraction fits well with stoichiometric of ligand-capped NCs. Excess monomers are left in supernatant, and thus achieving automatically purification of NCs in the water-ethanol co-environment. By adjusting the volume ratios of water and ethanol in bi-solvent system, different-sized purified NCs can be controlled. Besides, this water-ethanol co-environment can be used in both thermal-promoted and hydrazine-promoted growth.

Topics: Automation; Cadmium Compounds; Ethanol; Nanoparticles; Tellurium; Water

A distance-dependent electrochemiluminescence resonance energy transfer (ERET) system based on CdTe nanocrystals and Au nanoclusters (Au NCs) was designed with the aid of ligase for highly selective detection of microRNA (miRNA). First, Au NCs functionalized hairpin DNA was synthesized via Au-S chemistry, and characterized with transmission electron microscopy and dynamic light scattering. The resulting hairpin DNA-Au NCs composite can be bound to the carboxylated CdTe nanocrystals via amide reaction on glass carbon electrode. The strong interaction between CdTe nanocrystals and AuNCs led to the electrochemiluminescence (ECL) quenching of CdTe nanocrystals. In the presence of assistant DNA and miRNA, the ligase can selectively ligate both of them on the strand of the hairpin DNA to form long DNA-RNA heteroduplexes. Thus the ECL signal was recovered due to the blocking of the ERET. As a comparison, when directly opening the hairpin DNA by the target, the ECL emission signal is weak owing to the presence of ERET effect at the short distance. Based on the distance-dependent ERET, a 'signal on' ECL system was utilized for the detection of miRNA with the advantages of 6 orders magnitude linear range and excellent sequence specificity. The total detection processing time of the biosensor was approximately 70 min. By substituting the hairpin DNA with different sequences, this strategy as a new signal transduction approach could be conveniently extended for detection of other short miRNA and DNA.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Gold; Limit of Detection; Luminescent Measurements; MicroRNAs; Nanoparticles; Nanostructures; Tellurium

Both CdTe and CdTe/CdS/ZnS quantum dots induce similar levels of autophagy in PC12 and HEK293 cells, while the former exhibits higher toxicity. Low levels of cadmium ions are not sufficient to induce either autophagy or cytotoxicity by themselves. Interestingly, the combination of cadmium ions and CdTe/CdS/ZnS mimics the toxic effect of CdTe, suggesting that autophagy sensitizes cells to cadmium ions.

Topics: Animals; Apoptosis; Autophagy; Cadmium; Cadmium Compounds; Cell Survival; HEK293 Cells; Humans; Ions; PC12 Cells; Quantum Dots; Rats; Tellurium

Novel luminescent ratiometric nanosensors (QD-NAPTHs) were prepared based on cadmium telluride (CdTe655) quantum dots as luminescent nanoscaffolds with naphthyridine dyes as fluorescent receptors. This biosensing bifluorophoric nanosystem has been designed to achieve detection of guanosine 3',5'-cyclic monophosphate (cyclic GMP) in buffered media. Cyclic GMP is a secondary messenger that is an important factor for detecting cancer, diabetes and, cardiovascular diseases. Due to low concentration levels, even in pathological conditions, sensitive cGMP detection remains a challenge for modern biomedical diagnostics. Here, QD-NAPTH nanosensors were tested in the presence of a target nucleotide and with various structural cGMP analogues. Steady-state fluorescence spectroscopy was used to monitor a change in the nucleotide concentration. A 5-fold increase in naphthyridine fluorescence with a simultaneous decrease in QD luminescence was observed after adding 50 μM of cGMP. Using this novel nanosystem with ratiometric detection, it was possible to recognize cGMP with limit of detection (3σ) equal to 70 ng/ml. Moreover, the enhancement in fluorescence upon interaction with the target nucleotide constitutes a favourable approach towards the detection of cGMP in buffered media. These bifluorophoric nanosensors have a potential for application in fluorescence microscopy imaging and in-vitro assays.

Topics: Biosensing Techniques; Cadmium Compounds; Cyclic GMP; Nanoparticles; Naphthyridines; Tellurium

Quantum dots (QDs) are semiconductor nanocrystals with unique optical properties. Different proteins or polymers are commonly bound to their surfaces to improve biocompatibility. However, such surface modifications may not provide sufficient protection from cytotoxicity due to photodegradation and oxidative degradation. In this study, the cytotoxic effects of QDs, CdTe, and CdSe/ZnS were investigated using cadmium-resistant cells. CdTe QDs significantly reduced cell viability, whereas, CdSe/ZnS treatment did not markedly decrease the cell number. CdTe QDs were cytotoxic in cadmium-resistant cells suggesting that internalized QDs degraded and cadmium ions contributed to the cytotoxic effects. CdTe QDs were consistently more cytotoxic than CdSe/ZnS QDs, but both QDs as well as cadmium ions activated heat shock protein 70B' promoter. QDs themselves are likely to contribute to HSP70B' promoter activation in cadmium-resistant cells, because CdSe/ZnS QDs do not release sufficient cadmium to activate this promoter.

Topics: Animals; Cadmium; Cadmium Compounds; Cell Survival; Heat-Shock Response; Hot Temperature; HSP70 Heat-Shock Proteins; Mice; Nanoparticles; Promoter Regions, Genetic; Quantum Dots; Selenium Compounds; Surface Properties; Tellurium

The aim of this work is the evaluation of the design for a nonconventional PET scanner, the voxel imaging PET (VIP), based on pixelated room-temperature CdTe detectors yielding a true 3-D impact point with a density of 450 channels/cm(3), for a total 6 336 000 channels in a seamless ring shaped volume. The system is simulated and evaluated following the prescriptions of the NEMA NU 2-2001 and the NEMA NU 4-2008 standards. Results show that the excellent energy resolution of the CdTe detectors (1.6% for 511 keV photons), together with the small voxel pitch (1 × 1 × 2 mm(3)), and the crack-free ring geometry, give the design the potential to overcome the current limitations of PET scanners and to approach the intrinsic image resolution limits set by physics. The VIP is expected to reach a competitive sensitivity and a superior signal purity with respect to values commonly quoted for state-of-the-art scintillating crystal PETs. The system can provide 14 cps/kBq with a scatter fraction of 3.95% and 21 cps/kBq with a scatter fraction of 0.73% according to NEMA NU 2-2001 and NEMA NU 4-2008, respectively. The calculated NEC curve has a peak value of 122 kcps at 5.3 kBq/mL for NEMA NU 2-2001 and 908 kcps at 1.6 MBq/mL for NEMA NU 4-2008. The proposed scanner can achieve an image resolution of ~ 1 mm full-width at half-maximum in all directions. The virtually noise-free data sample leads to direct positive impact on the quality of the reconstructed images. As a consequence, high-quality high-resolution images can be obtained with significantly lower number of events compared to conventional scanners. Overall, simulation results suggest the VIP scanner can be operated either at normal dose for fast scanning and high patient throughput, or at low dose to decrease the patient radioactivity exposure. The design evaluation presented in this work is driving the development and the optimization of a fully operative prototype to prove the feasibility of the VIP concept.

Topics: Animals; Brain; Cadmium Compounds; Humans; Image Processing, Computer-Assisted; Mice; Models, Biological; Phantoms, Imaging; Positron-Emission Tomography; Signal Processing, Computer-Assisted; Tellurium

The size dependence of the temperature coefficient (sensitivity) of the photoluminescence (PL) peak position of CdTe quantum dots stabilized by thioglycolic acid in aqueous solution has been investigated. Temperature sensitivity increases as the average radius of CdTe quantum dots decreases. This must be taken into account in the design of solar light concentrators and light-emmiting diode-monitors as well as other technologies in which a fine tuning of the light emission is important.

Topics: Cadmium Compounds; Luminescence; Particle Size; Quantum Dots; Solutions; Surface Properties; Tellurium; Temperature; Thioglycolates; Water

CdTe quantum dots, 3.28 nm in size, were synthesized using a one-step method in an aqueous medium. The CdTe quantum dots were successfully employed as hybrid phosphors for white light-emitting diode (LED) devices by combining them with yellow-emitting YAG:Ce phosphor. The color-rendering index value and International Commission on illumination coordinates for hybrid phosphor white LEDs were 75 and (x = 0.30, y = 0.29), respectively. Compared with conventional phosphors, semiconductor quantum dots have larger band gap energy and broader absorption features, and can be excited more efficiently by optical pumping sources. The results confirmed that the high color-rendering index value of the white LED was due to the CdTe quantum dots introduced in the hybrid phosphor system.

Topics: Cadmium Compounds; Cerium; Lasers, Solid-State; Light; Luminescence; Luminescent Agents; Quantum Dots; Tellurium

We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies.

Topics: Animals; Cadmium Compounds; Cell Death; Cell Line, Tumor; Cell Membrane; Cell Survival; Cells; Fluorescent Dyes; Humans; Light; Mice; Microscopy, Fluorescence; NIH 3T3 Cells; Quantum Dots; Receptor, ErbB-2; Reproducibility of Results; Tellurium; Thioglycolates; X-Ray Diffraction

In this paper, we fabricated novel carboxymethyl chitosan-coated CdTe quantum dots (CMC-CdTe QDs) via the electrostatic interaction between amino groups in the carboxymethyl chitosan polymeric chains and carboxyl groups of the CdTe QDs. Carboxymethyl chitosan on the surface of CdTe QDs had strong binding ability with Zn(2+), resulting in the obvious enhancement of the photoluminescence of CdTe QDs. The photoluminescence intensity of CMC-CdTe QDs probe was proportional to the concentration of Zn(2+) in the range of 5.0 × 10(-6) to 5.0 × 10(-3) mol l(-1). The detection limit for Zn(2+) was 4.5 × 10(-6) mol l(-1). The experimental results indicate that the CMC-CdTe QDs possess favorable cell compatibility, good sensitivity and selectivity for intracellular Zn(2+) sensing, and are promising candidates for cellular imaging and sensing in prostate cancer cells. The present study also provides an approach for the further development of nanoprobes dedicated to intracellular sensing.

Topics: Cadmium Compounds; Chitosan; Fluorescence; Humans; Intracellular Space; Ions; Male; Molecular Probes; Prostatic Neoplasms; Quantum Dots; Tellurium; Time Factors; Zinc

Rapid and sensitive assay of thrombin and its inhibition in a high-throughput manner is of great significance in the diagnostic and pharmaceutical fields. In this article, we developed a novel biosensor for the detection of thrombin and its inhibition based on the aggregation behavior of the unmodified CdTe QDs. A cationic substrate peptide of thrombin (GGLVPRGSCC-NH2, S-peptide) can attach to the surface of CdTe QDs, partly balance their surface negative charge, and induce the aggregation of QDs, which results in the fluorescence quenching of QDs. After hydrolysis of S-peptide by thrombin, two kinds of shorter peptides (P1-peptide, GGLVPR, and P2-peptide, GSCC) are produced. The uncharged P2-peptide rather than the cationic P1-peptide would bind to QDs. Hence, the CdTe QDs were kept stable in the solution with the fluorescence being maintained. The change of fluorescence intensity would sensitively respond to thrombin activity and its inhibition. Fluorescence spectroscopy, transmission electron microscopy and dynamic light scattering were performed to discuss the quenching mechanism. Under optimized conditions, this method enables measurement of thrombin in the range of 10-100 μU/mL with the detection limit of 1.5 μU/mL. Not only in buffer, but also in blood serum, such sensor exhibited extraordinarily high sensitivity and excellent specificity. In addition, the typical inhibitor of thrombin, hirudin, was also successfully assayed by this method (from 2 μU/mL to 30 μU/mL with the LOD of 0.21 μU/mL). Furthermore, the present approach could also be potentially extended to other proteases and their inhibitors detection with unmodified CdTe QDs.

Topics: Amino Acid Sequence; Biosensing Techniques; Cadmium Compounds; Humans; Limit of Detection; Peptides; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thrombin

Novel thermoresponsive CdTe/ZnS quantum dots (QDs) decorated with a copolymer ligand (CPL) containing 8-hydroxyquinoline and NIPAM units are prepared through coordinate bonding in aqueous solution. The dependence of the morphology and optical properties of the QDs/CPL assemblies formed via coordinate bonding on the experimental conditions is studied. The coordinate induced self-assemblies are observed by controlling the molar ratio of QDs and CPL. The self-organized structure of QDs/CPL proceeds through a first step of QDs-chains, followed by a necklace-like single annular chain, and subsequently increases its annular chain structure, forming a network. The CPL functionalized QDs can emit multiple colors from the cooperating interaction between the inherent emission (606 nm) of the QDs and the surface-coordinated emission (517 nm) of the CPL complex formed on the QD surface. For QDs-CPL systems, both Förster resonance energy transfer (FRET) and a high rate of photoinduced electron transfer (PET) are simultaneous, the latter mainly contributing to PL quenching. The thermoresponsive QDs/CPL assemblies also exhibit dual reversible PL properties between the inherent emission of QDs and surface-coordinated emission.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Microscopy, Electron, Transmission; Polymers; Quantum Dots; Sulfides; Tellurium; Zinc Compounds

A novel epitope molecularly imprinted polymer (EMIP) for specific recognition and direct fluorescent quantification of the target protein bovine serum albumin (BSA) was demonstrated where polymerization was performed on the surface of silica nanospheres embedded CdTe quantum dots (QDs). The synthetic peptide derived from the surface-exposed C-terminus of bovine serum albumin (BSA, residues 599-607) was selected as the template molecule. The resulting EMIP film was able to selectively capture the template peptide and the corresponding target protein BSA via the recognition cavities. Based on the fluorescence quenching, the EMIP-coated QDs (molecular imprinted polymer coating CdTe QDs using epitope as the template) nanospheres were successfully applied to the direct fluorescence quantification of BSA. Compared with BMIP-coated QDs (molecular imprinted polymer coating CdTe QDs using BSA as the template), the imprinting factor and adsorption capacity of EMIP-coated QDs were greatly increased. The prepared EMIP-coated QDs can also discriminate even one mismatched sequences from the original sequences of the epitope of the BSA. The practical analytical performance of the EMIP-coated QDs was examined by evaluating the detection of BSA in the bovine calf serum sample with satisfactory results. In addition, the resulting EMIP-coated QDs nanospheres were also successfully applied to separating BSA from the bovine blood sample.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Cattle; Limit of Detection; Polymerization; Polymers; Quantum Dots; Serum Albumin, Bovine; Silicon Dioxide; Spectrometry, Fluorescence; Surface Properties; Tellurium

Estimation of left ventricular ejection fraction (LVEF) with equilibrium 99MTc-HSA equilibrium radionuclide angiography (MUGA) is frequently used for assessing cardiac function. The purpose of this study was to compare intra- and interobserver variation between three different gamma cameras.. Eighty-two patients, scanned in the same sequential order on the three cameras. Each acquisition was analyzed twice by two technologists. Inter- and intraobserver variations were calculated as the coefficient of variation and the 95% confidence interval for limits of agreement between each sequence of analyses for each of the three cameras.. The lowest intraobserver variations in LVEF for the two NaI-detector cameras were 3.1% (-4.0% to 3.5%) for the planar and 3.4% (-4.2% to 4.5%) for SPECT (P ≤ 0.001-0.019), the highest result for the CZT SPECT camera was 2.6% (-2.9% to 3.1%). Similarly, interobserver variation was 4.8% (-4.8% to 6.4%) and 4.9% (-5.4% to 7.5%), respectively, for each of the NaI-detector cameras and 3.3% (-3.4% to 4.3%) for the CZT SPECT camera (P ≤ 0.001-0.008).. The CZT detector camera was superior to both NaI detector cameras regarding intra- and interobserver variation. The CZT SPECT camera may identify changes in LVEF with greater certainty than its NaI detector-equipped counterparts.

Topics: Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Female; Gamma Cameras; Gated Blood-Pool Imaging; Humans; Image Enhancement; Male; Middle Aged; Reproducibility of Results; Sensitivity and Specificity; Tellurium; Ventricular Dysfunction, Left; Zinc

Synthesis of magnetic Fe3O4/SiO2/graphene-CdTe QDs/chitosan nanocomposites (FGQCs) is investigated with respect to their potential of improving the drug loading content above that of magnetic/fluorescent bifunctional nanocomposites. To evaluate the performance of the FGQCs, their surface morphology was thoroughly assessed. The in vitro interaction between the FGQCs and heptoma cell line smmc-7721 cells was observed for the first time by TEM ultrathin section imaging. At an excitation wavelength of 365 nm, the graphene-QDs exhibit a strong luminescence in aqueous environments. The loading content and entrapment efficiency of the FGQCs were 70% and 50%, respectively. The cytotoxicity of this novel drug delivery system was evaluated in vitro using heptoma cell line smmc-7721 and quantified by the 3-(4,5-dimethylthiazol-z-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results show that FGQCs are a promising new multifunctional material for drug delivery in biological and medical applications.

Topics: Biocompatible Materials; Cadmium Compounds; Cell Death; Cell Line, Tumor; Chitosan; Drug Delivery Systems; Ferric Compounds; Graphite; Humans; Magnetic Phenomena; Nanocomposites; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) have gained significant attention due to their superior optical properties and wide usage in biological and biomedical studies. In recent years, there has been intense concern regarding the in vivo toxicity of QDs. This study was undertaken to examine the toxicity of CdTe QDs on hematopoiesis in an invertebrate model organism, Bombyx mori. Vascular injection of sub-lethal doses of QDs in B. mori larvae caused time- and dose-dependent damage in the hematopoietic organ and hematocytes. QDs with the maximum emission wavelength of 530 nm (QDs530) were quickly observed in cystocytes and plasmacytes, and gradually bleached their green fluorescence, followed by a decrease in peripheral hematocytes. Additionally, the proportion of abnormal hematocytes increased. In marked contrast, QDs with the maximum emission wavelength of 720 nm (QDs720) were quickly surrounded by hematocytes and subsequently enriched in cystocytes like the human's leukocytes, but with weaker cytotoxicity. QDs exposure promoted the mitotic nucleus in prohemocytes and hematocytes similar to peripheral blood stem cells in humans, but aggravated apoptosis. A decrease in hematopoiesis was accompanied by shrinkage and death of hematopoietic organs via an increase in reactive oxygen species. QDs with smaller size resulted in more severe hematopoiesis toxicity.

Topics: Animals; Apoptosis; Bombyx; Cadmium Compounds; Cell Count; Cell Nucleus; Hematopoiesis; Hemocytes; Microscopy, Fluorescence; Mitosis; Models, Animal; Organ Specificity; Quantum Dots; Reactive Oxygen Species; Tellurium; Toxicity Tests

We have developed a simple and an economical one-pot method to synthesize water-soluble CdTe quantum dots (QDs) using hydroxylamine hydrochloride (HAH) as reduction and l-cysteine (CYS) as the ligand. The size of the CdTe QDs could easily be controlled by the duration of reflux and monitored by absorption and photoluminescence spectra. The factors influencing the photoluminescence quantum yields (PL QYs) on the QYs of CdTe NCs were investigated and the optimum conditions were determined. Under the optimum conditions (pH=11.0, the concentration of Cd(2+) was 1.0mmolL(-1) and the molar ratio of Cd(2+):Te(2)(-):CYS:HAH was 1:0.05:2.4:5), photoluminescence quantum yields of the CdTe QDs have been improved significantly and the maximum QYs of the QDs can achieve to 47%. The QDs were characterized by Fourier transform infrared spectrometry (FTIR), transmission-electron microscopy (TEM) and X-ray powder diffraction (XRD). The XRD patterns indicated that CdS was formed in the preparation process of CdTe QDs. This CdS shell could effectively passivate the surface trap states, and enhance the PL QY and stability of the CdTe QDs.

Topics: Cadmium Compounds; Cysteine; Hydroxylamine; Luminescence; Oxidation-Reduction; Quantum Dots; Tellurium; X-Ray Diffraction

A fluorescence polarization homogenous system based on CdTe/CdS QDs that employed a K(+)-mediated G-quadruplex as an enhancer was identified for sensitive and selective detection of Hg(2+) and biothiols in complex samples.

Topics: Cadmium Compounds; Fluorescence Polarization; G-Quadruplexes; Mercury; Potassium; Quantum Dots; Sulfhydryl Compounds; Sulfides; Tellurium

A simple and sensitive method for quantification of nanomolar copper with a detection limit of 1.2×10(-10)M and a linear range from 10(-9) to 10(-8)M is reported. For the most useful analytical concentration of quantum dots, 1160μg/ml, a 1/Ksv value of 11μM Cu(2+) was determined. The method is based on the interaction of Cu(2+) with glutathione-capped CdTe quantum dots (CdTe-GSH QDs) synthesized by a simple and economic biomimetic method. Green CdTe-GSH QDs displayed the best performance in copper quantification when QDs of different sizes/colors were tested. Cu(2+) quantification is highly selective given that no significant interference of QDs with 19 ions was observed. No significant effects on Cu(2+) quantification were determined when different reaction matrices such as distilled water, tap water, and different bacterial growth media were tested. The method was used to determine copper uptake kinetics on Escherichia coli cultures. QD-based quantification of copper on bacterial supernatants was compared with atomic absorption spectroscopy as a means of confirming the accuracy of the reported method. The mechanism of Cu(2+)-mediated QD fluorescence quenching was associated with nanoparticle decomposition.

Topics: Biological Transport; Biomimetics; Cadmium Compounds; Cells, Cultured; Copper; Culture Media; Escherichia coli; Glutathione; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Time Factors; Water

We compared the effects of several ligands frequently used in aqueous synthesis, including L-cysteine, L-cysteine hydrochloride, N-acetyl-L-cysteine (NAC), glutathione and 3-mercaptopropionic acid, for microwave synthesis of CdTe quantum dots (QDs) in a sealed vessel with varied temperatures and times, and then developed a rapid microwave-assisted protocol for preparing highly luminescent, photostable and biocompatible CdTe/CdS/ZnS core-multishell QDs. The effects of molecular structures of these ligands on QD synthesis under high temperatures were explored. Among these ligands, NAC was found to be the optimal ligand in terms of the optical properties of resultant QDs and reaction conditions. The emission wavelength of NAC-capped CdTe QDs could reach 700 nm in 5 min by controlling the reaction temperature, and the resultant CdTe/CdS/ZnS core-multishell QDs could achieve the highest quantum yields up to 74% with robust photostability. In addition, the effects of temperature, growth time and shell-precursor ratio on shell growth were examined. Finally, cell culturing indicated the low cytotoxicity of CdTe/CdS/ZnS core-multishell QDs as compared to CdTe and CdTe/CdS QDs, suggesting their high potential for applications in biomedical imaging and diagnostics.

Topics: Biocompatible Materials; Cadmium Compounds; Cell Survival; Dose-Response Relationship, Drug; HEK293 Cells; Humans; Ligands; Luminescence; Microwaves; Molecular Structure; Particle Size; Quantum Dots; Structure-Activity Relationship; Sulfides; Surface Properties; Tellurium; Temperature; Zinc Compounds

Due to the high importance of detecting DNA with both fast speed and high sensitivity, we proposed a new dsDNA detection method relying on a novel single-color fluorescence "off-on" switch system. Water-soluble glutathione capped CdTe QDs (emission at 605 nm) was prepared for taking advantage of the readily tunable emission property of QDs. Initially, QDs was completely quenched by the Ru(phen)2(dppz)(2+), as the spontaneous formation of QDs-Ru assembling dyads. Then, in the case of the addition of dsDNA, the Ru(phen)2(dppz)(2+) was removed away from the CdTe QDs, producing free CdTe QDs and the Ru-dsDNA complex. Both of them could be excited at the same wavelength and emit overlaid fluorescence. This single-color fluorescence "off-on" signal was sensitive to the concentration of dsDNA. Native dsDNA with the concentration of 10 pg/mL could be detected when 0.5 nM CdTe QDs was used, and ssDNA, RNA or BSA had no interference on it. With this system, the dsDNA samples of hepatitis B virus (HBV) patients were tested. The results were in good agreement with those detected by fluorescence quantitative PCR (P>0.05), and for those samples with very low DNA concentrations, this system could provide more accurate results, demonstrating the possible clinical applicability of this "off-on" switch system. For this system, chemical conjugation or labeling of probes is not required, and unmodified native DNA targets could be detected in less than half an hour. Therefore, a simple, fast, sensitive, low cost, highly selective and practically applicable detection system for dsDNA has been described.

Topics: Biosensing Techniques; Cadmium Compounds; Coordination Complexes; DNA, Viral; Fluorescent Dyes; Hepatitis B; Hepatitis B virus; Humans; Quantum Dots; Ruthenium; Spectrometry, Fluorescence; Tellurium

In this paper, we have elucidated the fundamental principle of employing CV to investigate the band structures of semiconductor nanocrystals (SNCs), and have also built up an optimal protocol for performing such investigation. By utilizing this protocol, we are able to obtain well-defined and characteristic electrochemical redox signals of SNCs, which allows us to intensively explore the influences of the particle size, the surface ligand and particle composition on the band structures of CdSe, CdTe and their alloy nanocrystals. The size-, ligand- and composition-dependent band structures of CdSe and CdTe nanocrystals (NCs) have therefore been mapped out, respectively, which are generally consistent with the previous theoretical and experimental reports. We believe that the optimal protocol and the original results regarding electrochemical characterization of SNCs demonstrated in this paper will definitely benefit the better understanding, modulation and application of the unique electronic and optical properties of SNCs.

Topics: Alloys; Cadmium Compounds; Electrochemical Techniques; Ligands; Particle Size; Quantum Dots; Selenium Compounds; Tellurium

Glycyrrhetic acid (GA), a pentacyclic triterpenoid derivative obtained from hydrolysis of glycyrrhizic acid, was found to have synergistic anti-asthmatic effects with the β2-adrenergic receptor (β2AR) agonist via the β2AR-mediated pathway. This study visualized the location of GA on a human cell expressing β2AR via chemical biological approaches. A CdTe/ZnS quantum dot modified with an alkynyl group (QD-AL) was first synthesized, and an azide-terminal GA (ATGA) was also prepared. The QD-AL was used for fluorescence visualization of the distribution of GA on human embryonic kidney 293 cells expressing fusion β2AR (HEK293-β2AR) through the "click reaction" between QD-AL and ATGA. The average size of the QD-AL nanoparticle was about 10 nm, and its fluorescent emission wavelength was 620 nm. The location of GA on the HEK293-β2AR cell membrane can be visualized by the click reaction (between QD-AL and ATGA). The ability of QD-AL targeting to ATGA on the cell membrane of a HEK293-β2AR cell was further investigated using both confocal laser-scanning microscopy and a cellular uptake-inhibition assay. The results reveal that QD-AL can recognize ATGA on the cell membrane through the click reaction, which provides a new approach for visualizing the location of GA on the cell in an indirect way, and it can be applied to explore the synergistic anti-asthmatic mechanism of GA with β2AR agonist through the β2AR mediated pathway.

Topics: Cadmium Compounds; Click Chemistry; Glycyrrhetinic Acid; HEK293 Cells; Humans; Microscopy, Confocal; Particle Size; Quantum Dots; Receptors, Adrenergic, beta-2; Tellurium

In this study, it was found that horseradish peroxidase (HRP)-mimicking DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)-H2O2 system, whereas HRP could not enhance the CL intensity. The CL enhancement mechanism was investigated, and the CL enhancement was supposed to originate from the catalysis of HRP-mimicking DNAzyme on the CL reaction between CdTe QDs and H2O2. Meantime, compared with CdTe QDs-H2O2 CL system, H2O2 concentration was markedly decreased in QDs-H2O2-HRP-mimicking DNAzyme CL system, improving the stability of QDs-H2O2 CL system. The QDs-based CL system was used to detect sensitively CdTe QDs and HRP-mimicking DNAzyme (as biologic labels). This work gives a path for enhancing CL efficiency of QDs system, and will be helpful to promote the step of QDs application in various fields such as bioassay and trace detection of analyte.

Topics: Cadmium Compounds; Calibration; DNA, Catalytic; Horseradish Peroxidase; Hydrogen Peroxide; Luminescent Measurements; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Tellurium

An automated multi-pumping flow system is proposed for the chemiluminometric determination of ascorbic acid in pharmaceutical formulations, relying on the ability of semiconductor nanocrystals to generate short-lived reactive species upon photo-irradiation. A photo-unit based on visible-light-emitting diodes is used to photo-excite cadmium telluride (CdTe) quantum dots capped with glutathione, leading to the generation of radicals that react with luminol under alkaline conditions, yielding the chemiluminescence. Ascorbic acid acts as a radical scavenger, preventing the oxidation of luminol, thus ensuring a concentration-dependent chemiluminescence quenching. After system optimization, a linear working range of 5.0 × 10(-7) to 5.0 × 10(-6) mol/L ascorbic acid (r = 0.9967, n = 5) was attained, with a detection limit of 3.05 × 10(-7) mol/L and a sampling rate of 200/h. The flow system was applied to the analysis of pharmaceutical formulations and the results were in good agreement with those obtained by the reference titrimetric procedure (RD < ± 4.3%, n = 7).

Topics: Ascorbic Acid; Cadmium Compounds; Chemistry, Pharmaceutical; Glutathione; Luminescent Measurements; Luminol; Molecular Structure; Photochemical Processes; Quantum Dots; Reactive Oxygen Species; Tellurium

Stable protein one (SP1) has been demonstrated as an appealing building block to design highly ordered architectures, despite the hybrid assembly with other nano-objects still being a challenge. Herein, we developed a strategy to construct high-ordered protein nanostructures by electrostatic self-assembly of cricoid protein nanorings and globular quantum dots (QDs). Using multielectrostatic interactions between 12mer protein nanoring SP1 and oppositely charged CdTe QDs, highly ordered nanowires with sandwich structure were achieved by hybridized self-assembly. QDs with different sizes (QD1, 3-4 nm; QD2, 5-6 nm; QD3, ∼10 nm) would induce the self-assembly protein rings into various nanowires, subsequent bundles, and irregular networks in aqueous solution. Atomic force microscopy, transmission electron microscopy, and dynamic light scattering characterizations confirmed that the size of QDs and the structural topology of the nanoring play critical functions in the formation of the superstructures. Furthermore, an ordered arrangement of QDs provides an ideal scaffold for designing the light-harvesting antenna. Most importantly, when different sized QDs (e.g., QD1 and QD3) self-assembled with SP1, an extremely efficient Förster resonance energy transfer was observed on these protein nanowires. The self-assembled protein nanostructures were demonstrated as a promising scaffold for the development of an artificial light-harvesting system.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Light; Models, Molecular; Protein Conformation; Proteins; Quantum Dots; Static Electricity; Tellurium

A novel procedure for the optosensing of clenbuterol and melamine was developed using molecularly imprinted polymer-capped CdTe quantum dots (MIP-CdTe QDs). The MIP-CdTe QDs were synthesized by a radical polymerization process among CdTe QDs, a template, 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS). The sizes of the MIP-CdTe particles were controlled by the speed of polymerization, concentration of the template, concentration of the quantum dots, and the ratio of template, monomer and cross-linker. Excellent selectivity and high sensitivity of MIP-CdTe QDs toward clenbuterol/melamine molecules were observed based on the fluorescence quenching of QDs. Experimental results showed that the optimum molar ratios of template, monomer, and cross-linker were 1:8:20 and 1:4:20 for analyzing clenbuterol and melamine, respectively. Under optimum conditions, these MIP-CdTe QDs showed a limit of detection of 0.4 μM (120 ng/mL) for clenbuterol and 0.6 μM (75 ng/mL) for melamine. The feasibility of the developed method in real samples was successfully evaluated through the analysis of clenbuterol and melamine in milk and liver samples with satisfactory recoveries of 92-97%. The MIP-CdTe QDs could be easily regenerated for subsequent sample analysis with water.

Topics: Adrenergic beta-Agonists; Animals; Biosensing Techniques; Cadmium Compounds; Clenbuterol; Food Contamination; Limit of Detection; Milk; Molecular Imprinting; Propylamines; Quantum Dots; Silanes; Tellurium; Triazines

Considering the fact that polyphenols have versatile activity in-vivo, its detection and quantification is very much important for a healthy diet. Laccase enzyme can convert polyphenols to yield mono/polyquinones which can quench Quantum dots fluorescence. This phenomenon of charge transfer from quinones to QDs was exploited as optical labels to detect polyphenols. CdTe QD may undergo dipolar interaction with quinones as a result of broad spectral absorption due to multiple excitonic states resulting from quantum confinement effects. Thus, "turn-off" fluorescence method was applied for ultrasensitive detection of polyphenols by using laccase. We observed proportionate quenching of QDs fluorescence with respect to polyphenol concentration in the range of 100 µg to 1 ng/mL. Also, quenching of the photoluminescence was highly efficient and stable and could detect individual and total polyphenols with high sensitivity (LOD-1 ng/mL). Moreover, proposed method was highly efficient than any other reported methods in terms of sensitivity, specificity and selectivity. Therefore, a novel optical sensor was developed for the detection of polyphenols at a sensitive level based on the charge transfer mechanism.

Topics: Biosensing Techniques; Cadmium Compounds; Enzymes, Immobilized; Laccase; Limit of Detection; Polyphenols; Quantum Dots; Rhus; Spectrometry, Fluorescence; Tellurium

Novel, water-soluble CdTe quantum dots (QDs) capped with β-cyclodextrin (β-CD) and ~ 4.0 nm in diameter were synthesized in aqueous solution, and characterized using transmission electron microscopy (TEM). A fluorescence-sensing system based on the photoinduced electron transfer (PET) of (mono-6-thio-β-CD)-CdTe QDs was then designed to measure the interaction of phenothiazine dyes [methylene blue (MB) and methylene green (MG)] with herring sperm DNA (hsDNA). This fluorescence-sensing system was based on a fluorescence "OFF-ON" mode. First, MB/MG adsorbed on the surface of (mono-6-thio-β-CD)-CdTe QDs effectively quenches the fluorescence of (mono-6-thio-β-CD)-CdTe QDs through PET. Then, addition of hsDNA restores the fluorescence intensity of (mono-6-thio-β-CD)-CdTe QDs, because hsDNA can bind with MB/MG and remove it from the as-prepared (mono-6-thio-β-CD)-CdTe QDs. In addition, detailed reaction mechanisms of the (mono-6-thio-β-CD)-CdTe QDs-MB/MG-hsDNA solution system were studied using optical methods, by comparison with the TGA-CdTe QDs-MB/MG-hsDNA solution system.

Topics: Animals; beta-Cyclodextrins; Cadmium Compounds; DNA; Fishes; Male; Methylene Blue; Molecular Structure; Quantum Dots; Spectrometry, Fluorescence; Spermatozoa; Tellurium

A new assay was developed for the determination of five quinolone antibiotic residues in foods, loxacin, enrofloxacin, ciprofloxacin, lomefloxacin, and norfloxacin, by micellar electrokinetic capillary chromatography with indirect laser-induced fluorescence, in which cadmium telluride quantum dots were used as a fluorescent background substance. Some factors that affected the peak height and the resolution were examined. The optimized running buffer was composed of 20 mM SDS, 7.2 mg/L quantum dots, and 10 mM borate at pH 8.8. The separation voltage was 20 kV. Under these conditions, five quinolone antibiotic residues were separated successfully within 8 min. The detection limits ranged from 0.003 to 0.008 mg/kg; the linear dynamic ranges were all 0.01 ∼ 10 mg/kg; and the average recoveries of the spiked samples were 81.4 ∼ 94.6 %. The assay can meet the requirement of maximum residue limits to these five quinolone antibiotics in the regulations of the European Union and Japan and has been applied for determining their residues in animal-derived food.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Cadmium Compounds; Chromatography, Micellar Electrokinetic Capillary; Ciprofloxacin; Enrofloxacin; European Union; Fluorescence; Fluoroquinolones; Hydrogen-Ion Concentration; Japan; Lasers; Limit of Detection; Loxapine; Norfloxacin; Quantum Dots; Quinolones; Spectrometry, Fluorescence; Tellurium

In this contribution, a simple and sensitive fluorescent sensor for the determination of both the three ruthenium anticancer drugs (1 to 3) and calf thymus DNA (ctDNA) was established based on the CdTe quantum dots (QDs) fluorescence "OFF-ON" mode. Under the experimental conditions, the fluorescence of CdTe QDs can be effectively quenched by ruthenium anticancer drugs because of the surface binding of these drugs on CdTe QDs and the subsequent photoinduced electron transfer (PET) process from CdTe QDs to ruthenium anticancer drugs, which render the system into fluorescence "OFF" status. The system can then be "ON" after the addition of ctDNA which brought the restoration of CdTe QDs fluorescence intensity, since ruthenium anticancer drugs broke away from the surface of CdTe QDs and inserted into double helix structure of ctDNA. The fluorescence quenching effect of the CdTe QDs-ruthenium anticancer drugs systems was mainly concentration dependent, which could be used to detect three ruthenium anticancer drugs. The limits of detection were 5.5 × 10(-8) M for ruthenium anticancer drug 1, 7.0 × 10(-8) M for ruthenium anticancer drug 2, and 7.9× 10(-8) M for ruthenium anticancer drug 3, respectively. The relative restored fluorescence intensity was directly proportional to the concentration of ctDNA in the range of 1.0 × 10(-8) M ∼ 3.0 × 10(-7) M, with a correlation coefficient (R) of 0.9983 and a limit of detection of 1.1 × 10(-9) M. The relative standard deviation (RSD) for 1.5 × 10(-7) M ctDNA was 1.5% (n = 5). There was almost no interference to some common chemical compounds, nucleotides, amino acids, and proteins. The proposed method was applied to the determination of ctDNA in three synthetic samples with satisfactory results. The possible reaction mechanism of CdTe QDs fluorescence "OFF-ON" was further investigated. This simple and sensitive approach possessed some potential applications in the investigation of interaction between drug molecules and DNA.

Topics: Animals; Antineoplastic Agents; Biosensing Techniques; Cadmium Compounds; Cattle; DNA; Fluorescence; Linear Models; Quantum Dots; Ruthenium; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

After an introduction of Timepix detector, results of these detectors with silicon and cadmium telluride detection layer in assessment of activity of short-lived radon decay products are presented. They were collected on an open-face filter by means of one-grab sampling method from the NRPI radon chamber. Activity of short-lived radon decay products was estimated from measured alpha decays of 218,214Po. The results indicate very good agreement between the use of both Timepix detectors and an NRPI reference instrument, continuous monitor Fritra 4. Low-level detection limit for EEC was estimated to be 41 Bq m(-3) for silicon detection layer and 184 Bq m(-3) for CdTe detection layer, respectively.

Topics: Air Pollutants, Radioactive; Cadmium Compounds; Equipment Design; Humans; Radiation Monitoring; Radiation Protection; Radon Daughters; Silicon; Tellurium

Recent developments have shown that high resolution phase contrast x-ray computed tomography (CT) of the breast can be performed at clinically compatible doses. Results have yet been obtained in vitro on full breasts, and the clinical translation of the technique seems more and more possible. This work presents a method to quickly estimate the average dose in the organ using the software GATE. The influence of different parameters on the dose distribution, like breast composition and thickness, and for preclinical test, the presence of a skin/PMMA external layer, has been investigated. Several correction factors, to be applied to the given dose database, are also introduced to allow the use of these results in geometries different from those studied here. An energy optimization study is presented that considers also the influence on the energy choice of x-ray detector. A simple analytical method to estimate the best energy that minimizes the dose-transmittance ratio in CT imaging is presented and compared with the results of simulations.

Topics: Breast; Cadmium Compounds; Databases, Factual; Humans; Mammography; Monte Carlo Method; Polymethyl Methacrylate; Radiation Dosage; Synchrotrons; Tellurium

The manipulation of the surface chemistry of semiconductor nanocrystals has been exploited to implement distinct sensing strategies in many analytical applications. In this work, reduced glutathione (GSH) was added at reaction time, as an electron-donor ligand, to markedly increase the quantum yield and the emission efficiency of MPA-capped CdTe quantum dots. The developed approach was employed in the implementation of an automated flow methodology for hydrogen peroxide determination, as this can oxidize GSH preventing its surface passivating effect and producing a manifest fluorescence quenching. After optimization, linear working calibration curve for hydrogen peroxide concentrations between 0.0025% and 0.040% were obtained (n=6), with a correlation coefficient of 0.9975. The detection limit was approximately 0.0012%. The developed approach was employed in the determination of H₂O₂ in contact lens preservation solutions and the obtained results complied with those furnished by the reference method, with relative deviations comprised between -1.18 and 4.81%.

Topics: Cadmium Compounds; Glutathione; Hydrogen Peroxide; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A simple and highly sensitive chemiluminescence (CL) method is reported for the determination of naphazoline hydrochloride (NH). It was found that the weak CL from the reaction of luminol and KIO4 in an alkaline medium could be highly amplified by cysteine-capped cadmium telluride quantum dots (QDs) and the enhanced CL was effectively quenched by NH and this finding was utilized as a basis for the determination of NH. The QDs were synthesized in aqueous medium and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis and photoluminescence spectroscopy. A possible mechanism was proposed for the CL system based on radical identification experiments, along with CL spectrum of the system. The experimental parameters were optimized by the reliable response surface methodology (RSM). Under the optimized experimental conditions, the proposed method allowed the determination of NH over the range of 5.0 × 10(-10) -2.0 × 10(-7) mol/L (r(2) = 0.9993, n = 10). The precision (RSD%) of the method, obtained from five replicate determinations of 2.0 and 150 nmol/L NH, was found to be 1.0% and 1.3%, respectively. The method was successfully applied to the determination of NH in pharmaceutical formulations and human urine and serum samples with results corroborated with the aid of those obtained from a standard method.

Topics: Cadmium Compounds; Calibration; Cysteine; Humans; Luminescent Measurements; Luminol; Microscopy, Electron, Transmission; Naphazoline; Ophthalmic Solutions; Quantum Dots; Reproducibility of Results; Tellurium; X-Ray Diffraction

We present here a new and alternative method that uses a Fluorescence Plate Reader in a different approach, not to study protein-protein interactions, but to evaluate the efficiency of the protein bioconjugation to quantum dots (QDs). The method is based on the QDs' native fluorescence and was successfully tested by employing two different QDs-proteins conjugation methodologies, one by promoting covalent binding and other by inducing adsorption processes. For testing, we used bioconjugates between carboxyl coated CdTe QDs and bovine serum albumin, concanavalin A lectin and anti-A antibody. Flow cytometry and fluorescence spectroscopy studies corroborated the results found by the Fluorescence Plate Reader assay. This kind of analysis is important because poor bioconjugation efficiency leads to unsuccessful applications of the fluorescent bioconjugates. We believe that our method presents the possibility of performing semi-quantitative and simultaneous analysis of different samples with accuracy taking the advantage of the high sensitivity of optical based measurements.

Topics: Cadmium Compounds; Flow Cytometry; Quantum Dots; Serum Albumin; Spectrometry, Fluorescence; Tellurium

High-quality colloidal photoluminescent (PL) CdTe(x)Se(1-x) quantum dots (QDs) with gradient distribution of components, consisting of Te-rich inner cores and Se-rich outer shells, were synthesized via a facile organic method using stearic acid as a capping agent. The transmission electron microscopy observation and X-ray diffraction analysis indicated that the CdTe(x)Se(1-x) QDs revealed a "dot" shaped morphology and exhibited a zinc-blende structure which located between those of bulk CdTe and CdSe (with the lattice parameters between those of bulk CdTe and CdSe). The ternary CdTe(x)Se(1-x) QDs were emitting in the red to near-infrared (NIR) range. In order to enhance the PL properties and reduce the sensitivity to oxidation of CdTe-based QDs, the CdTe(x)Se(1-x) QDs were coated with Cd(y)Zn(1-y)S multishells by using different growth kinetics of CdS and ZnS. The coated QDs exhibited a controlled red shift of PL compared with the initial CdTe(x)Se(1-x) cores and revealed much improved PL intensity. Because of thier tunable emission from red to NIR, these composite QDs open new possibilities in band gap engineering and in developing NIR fluorescent probes for biological imaging and detection.

Topics: Absorption; Biosensing Techniques; Cadmium; Cadmium Compounds; Fluorescent Dyes; Kinetics; Luminescence; Microscopy, Electron, Transmission; Photochemistry; Quantum Dots; Selenium; Semiconductors; Spectroscopy, Near-Infrared; Tellurium; X-Ray Diffraction; Zinc

In this study, anti-Vibrio parahaemolyticus polyclonal and monoclonal antibodies were prepared through intradermal injection immune and lymphocyte hybridoma technique respectively. CdTe quantum dots (QDs) were synthesized at pH 9.3, 98 °C for 1 h with stabilizer of 2.7:1. The fluorescence intensity was 586.499, and the yield was 62.43%. QD probes were successfully prepared under the optimized conditions of pH 7.4, 37 °C for 1 h, 250 μL of 50 mg/mL EDC · HCl, 150 μL of 4 mg/mL NHS, buffer system of Na2HPO4-citric acid, and 8 μL of 2.48 mg/mL polyclonal antibodies. As gold nanoparticles could quench fluorescence of quantum dots, the concentration of V. parahaemolyticus could be detected through measuring the reduction of fluorescence intensity in immune sandwich reaction composed of quantum dot probe, gold-labeled antibody, and the sample. For pure culture, fluorescence intensity of the system was proportional with logarithm concentration of antigen, and the correlation coefficient was 99.764%. The fluorescence quenching immunoassay based on quantum dots is established for the first time to detect Vibrio parahaemolyticus. This method may be used as rapid testing procedure due to its high simplicity and sensitivity.

Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Cadmium Compounds; Ethyldimethylaminopropyl Carbodiimide; Female; Fluorescent Dyes; Gold; Immunoassay; Metal Nanoparticles; Mice; Quantum Dots; Rabbits; Spectrometry, Fluorescence; Succinimides; Tellurium; Time Factors; Vibrio parahaemolyticus

Highly fluorescent CdTe quantum dots (QDs) with emission in red to near-infrared (NIR) wavelength were successfully prepared by using 3-mercaptobutyric acid (3MBA) as capping agent. The maximum of quantum yield (QY) could reach up to 82% for QDs with emission peak at 686 nm and FWHM of 66 nm at optimal conditions. The QY of these QDs could maintain above 65% in the 650-750 nm region and QDs with emission over 800 nm were still strong fluorescent (28-41%). These optical properties of CdTe quantum dots are among the best results prepared by the state-of-the-art methods, suggesting their promising applications in bio-imaging. The success of 3MBA as excellent capping agent in this method was attributed to the balanced chain length and methyl side chain in comparison to a series of linear and branched mercapto acids, namely thioglycolic acid, thiolactic acid, 3-mercaptopropionic acid, 4-mercaptobutyric acid, 5-mercaptovaleric acid, 4-mercaptovaleric acid and 3-mercapto-2-methylbutyric acid.

Topics: Butyrates; Cadmium Compounds; Crystallization; Infrared Rays; Materials Testing; Particle Size; Quantum Dots; Solubility; Spectrometry, Fluorescence; Tellurium; Water

Octachlorostyrene (OCS), a persistent and bioaccumulative toxicant (PBT), was assayed by fluorescence immunoassay based on the Förster resonance energy transfer (FRET) between CdTe quantum dots (QDs) and rhodamine B-labeled OCS (RB-OCS). Anti-OCS antibody produced in this lab is adsorbed on a microtiter plate. The RB-OCS competes with OCS for the highly specific immunoreaction with the anti-OCS antibodies adsorbed on the microtiter plate. The solution is then isolated and mixed with CdTe QDs as fluorescent donor which excite the emission of RB-OCS through FRET. As a result, the emission of CdTe QDs at 530 nm decreases, whereas the emission of RB-OCS at 580 nm increases. The ratio of fluorescence intensity at 580 nm to that at 530 nm is proportional to the RB-OCS concentration at a fixed CdTe QDs concentration, and consequently proportional to the OCS concentration. Selective and sensitive responses to OCS are achieved with a linear range of 8-80 nM and a LOD of 3.8 nM. Because OCS is quantified based on the fluorescence ratio, the sensor-to-sensor difference is greatly eliminated, making the proposed method a useful approach for in site scanning of OCS.

Topics: Biosensing Techniques; Cadmium Compounds; Environmental Monitoring; Environmental Pollutants; Equipment Design; Equipment Failure Analysis; Fluorescence Resonance Energy Transfer; Quantum Dots; Rhodamines; Spectrometry, Fluorescence; Styrenes; Tellurium

The PL lifetime optimization of CdTe QDs capped with TGA has yet to be understood from a perspective of growth kinetics. In this work, the growth kinetics and PL properties of CdTe QDs growing in aqueous solutions of two TGA concentrations, 0 mM and 57 mM, were systematically investigated using UV, TEM, and PL methods. CdTe QDs in 0 mM TGA solution were found to follow the mixed OA (Oriented Attachment)-OR (Ostwald Ripening) growth kinetics. The PL peaks experienced a red-shift with almost unchanged intensity and the PL lifetimes increased gradually. In 57 mM TGA solution, the QDs followed the OA dominated growth mechanism. The PL peak broadened greatly with a red-shift and its intensity decreased significantly. The PL lifetime increased much higher than that in 0 mM TGA solution. Based on the different growth kinetic models of the two systems, we suggest that in the low (0 mM) TGA solution, the increased surface defects induced by TGA desorption and the existence of partial internal defects caused by OA growth were the main reasons for the gradual increase of PL lifetime, while in high (57 mM) TGA solution, the increase of PL lifetime was ascribed to the abundant internal defects produced by OA collision. Finally, kinetic data showed the effect of the TGA concentration on crystal growth and PL lifetime of CdTe QDs. The results might provide guidance for understanding the mechanism behind the phenomena of ligand-related PL properties.

Topics: Cadmium Compounds; Crystallization; Kinetics; Luminescence; Particle Size; Quantum Dots; Surface Properties; Tellurium; Thioglycolates; X-Ray Diffraction

Daminozide (B9) is a growth inhibitor with important regulatory roles in plant growth and development. Locating and quantifying B9-binding proteins in plant tissues will assist in investigating the mechanism behind the signal transduction of B9. In this study, red fluorescent Mn-doped CdTe quantum dots (CdTeMn QDs) were synthesized by a high-temperature hydrothermal process. Since CdTeMn QDs possess a maximum fluorescence emission peak at 610nm, their fluorescence properties are more stable than those of CdTe QDs. A B9-CdTeMn probe was synthesized by coupling B9 with CdTeMn QDs. The fluorescence intensity of the probe is double that of CdTeMn QDs; its fluorescence stability is also superior under different ambient conditions. The probe retains the biological activity of B9 and is unaffected by interference from the green fluorescent protein present in plants. Therefore, we used this probe to label B9-binding proteins selectively in root tissue sections of mung bean seedlings. These proteins were observed predominantly on the surfaces of the cell membranes of the cortex and epidermal parenchyma.

Topics: Cadmium Compounds; Fabaceae; Fluorescent Dyes; Manganese; Microscopy, Fluorescence; Plant Growth Regulators; Plant Proteins; Plant Roots; Quantum Dots; Seedlings; Spectrometry, Fluorescence; Succinates; Tellurium

Based on the recovery of the quantum dot (QD) electrochemiluminescence (ECL) and exonuclease-catalyzed target recycling amplification, the development of a highly sensitive aptasensor for Ochratoxin A (OTA) detection is described. The duplex DNA probes containing the biotin-modified aptamer are immobilized on a CdTe QD composite film-coated electrode. The presence of the OTA target leads to effective removal of the biotin-aptamers from the electrode surface via exonuclease-catalyzed recycling and reuse of OTA, which prevents the attachment of streptavidin-alkaline phosphatase (STV-ALP) through biotin-STV interaction. The electron transfer (ET) from the excited state CdTe QD ([CdTe](⁎)) to the electro-oxidized species of the enzymatic product of ALP during the potential scan is thus inhibited and the QD ECL emission is restored for quantitative OTA detection. Due to the exonuclease-catalyzed target recycling amplification, the inhibition effect of ET is significantly enhanced to achieve sensitive detection of OTA down to 0.64 pg mL(-1). The proposed method is selective for OTA and can be used to monitor OTA in real red wine samples. Our developed ECL recovery-based aptasensor thus offers great potential for the development of new ECL sensing platforms for various target analytes.

Topics: Alkaline Phosphatase; Biosensing Techniques; Biotin; Cadmium Compounds; Calibration; Catalysis; DNA; Electrochemistry; Electrodes; Electrons; Equipment Design; Exonucleases; Food Analysis; Luminescence; Ochratoxins; Quantum Dots; Streptavidin; Tellurium; Wine

In this paper, we developed dopamine functionalized-CdTe quantum dots as fluorescence probes for the determination of l-histidine. Firstly, CdTe was covalently linked to dopamine to form a kind of fluorescence sensor with pyrocatechol structure on the surface. The photoluminescence intensity of CdTe-dopamine (QDs-DA) could be quenched by Ni(2+) due to the strong coordination interaction between the pyrocatechol structure of QDs-DA and Ni(2+). In the presence of l-histidine, Ni(2+) preferred to bind with l-histidine due to high affinity of Ni(2+) to l-histidine and the photoluminescence intensity of QDs-DA was recovered. The recovered photoluminescence intensity of QDs-DA was proportional to the concentration of l-histidine in the ranges of 1.0×10(-6)-1.0×10(-4)mol L(-1) and the detection limit was 5.0×10(-7)mol L(-1) respectively. The established method showed a good selectivity for l-histidine among other common amino acids, and it was applied for determination of l-histidine in human serum sample with satisfactory results.

Topics: Amino Acids; Body Fluids; Cadmium Compounds; Dopamine; Fluorescent Dyes; Histidine; Humans; Hydrogen-Ion Concentration; Light; Limit of Detection; Nickel; Photochemistry; Protein Binding; Quantum Dots; Regression Analysis; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Tellurium; Temperature

We designed a turn-on fluorescence assay for glyphosate based on the fluorescence resonance energy transfer (FRET) between negatively charged CdTe quantum dots capped with thioglycolic acid (TGA-CdTe-QDs) and positively charged gold nanoparticles stabilized with cysteamine (CS-AuNPs). Oppositely charged TGA-CdTe-QDs and CS-AuNPs can form FRET donor-acceptor assemblies due to electrostatic interactions, which effectively quench the fluorescence intensity of TGA-CdTe-QDs. The presence of glyphosate could induce the aggregation of CS-AuNPs through electrostatic interactions, resulting in the fluorescence recovery of the quenched QDs. This FRET-based method has been successfully utilized to detect glyphosate in apples with satisfactory results. The detection limit for glyphosate was 9.8 ng/kg (3σ), with the linear range of 0.02-2.0 μg/kg. The attractive sensitivity was obtained due to the efficient FRET and the superior fluorescence properties of QDs. The proposed method is a promising approach for rapid screening of glyphosate in real samples.

Topics: Cadmium Compounds; Citric Acid; Electrochemistry; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Food Contamination; Glycine; Glyphosate; Gold; Malus; Metal Nanoparticles; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates; Water

In this work, we developed an ultrasensitive "turn on-off" fluorescence nanosensor for lysozyme (Lyz) detection. The novel nanosensor was constructed with the carboxymethyl chitosan modified CdTe quantum dots (CMCS-QDs). Firstly, the CMCS-QDs were fabricated via the electrostatic interaction between amino groups in CMCS polymeric chains and carboxyl groups on the surface of QDs. In the fluorescence "turn-on" step, the strong binding ability between Zn(2+) and CMCS on the surface of QDs can enhance the photoluminescence intensity (PL) of QDs. In the following fluorescence "turn-off" step, the N-acetyl-glucosamine (NAG) section along the CMCS chains was hydrolyzed by Lyz. As a result, Zn(2+) was released from the surface of QDs, and the Lyz-QDs complexes were formed to quench the QDs PL. Under the optimal conditions, there was a good linear relationship between the PL of QDs and the Lyz concentration (0.1-1.2 ng/mL) with the detection limit of 0.031 ng/mL. The developed method was ultrasensitive, highly selective and fast. It has been successfully employed in the detection of Lyz in the serum with satisfactory results.

Topics: Biosensing Techniques; Cadmium Compounds; Chitosan; Fluorescence; Humans; Limit of Detection; Muramidase; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Zinc

Self-assembly of proteins and inorganic nanoparticles into terminal assemblies makes possible a large family of uniformly sized hybrid colloids. These particles can be compared in terms of utility, versatility and multifunctionality to other known types of terminal assemblies. They are simple to make and offer theoretical tools for designing their structure and function. To demonstrate such assemblies, we combine cadmium telluride nanoparticles with cytochrome C protein and observe spontaneous formation of spherical supraparticles with a narrow size distribution. Such self-limiting behaviour originates from the competition between electrostatic repulsion and non-covalent attractive interactions. Experimental variation of supraparticle diameters for several assembly conditions matches predictions obtained in simulations. Similar to micelles, supraparticles can incorporate other biological components as exemplified by incorporation of nitrate reductase. Tight packing of nanoscale components enables effective charge and exciton transport in supraparticles and bionic combination of properties as demonstrated by enzymatic nitrate reduction initiated by light absorption in the nanoparticle.

Topics: Cadmium Compounds; Colloids; Cytochromes c; Humans; Metal Nanoparticles; Molecular Docking Simulation; Nitrate Reductase; Pichia; Static Electricity; Tellurium

A novel quantum dots-based multifunctional nanovehicle (DOX-QD-PEG-FA) was designed for targeted drug delivery, fluorescent imaging, tracking, and cancer therapy, in which the GSH-CdTe quantum dots play a key role in imaging and drug delivery. To exert curative effects, the antineoplastic drug doxorubicin hydrochloride (DOX) was loaded on the GSH-CdTe quantum dots through a condensation reaction. Meanwhile, a polyethylene glycol (PEG) shell was introduced to wrap the DOX-QD, thus stabilizing the structure and preventing clearance and drug release during systemic circulation. To actively target cancer cells and prevent the nanovehicles from being absorbed by normal cells, the nanoparticles were further decorated with folic acid (FA), allowing them to target HeLa cells that express the FA receptor. The multifunctional DOX-QD-PEG-FA conjugates were simply prepared using the 'one pot' method. In vitro study demonstrated that this simple, multifunctional nanovehicle can deliver DOX to the targeted cancer cells and localize the nanoparticles. After reaching the tumor cells, the FA on the DOX-QD-PEG surface allowed folate receptor recognition and increased the drug concentration to realize a higher curative effect. This novel, multifunctional DOX-QD-PEG-FA system shows great potential for tumor imaging, targeting, and therapy.

Topics: Antibiotics, Antineoplastic; Cadmium Compounds; Doxorubicin; Drug Delivery Systems; Female; Folic Acid; Glutathione; HeLa Cells; Humans; Polyethylene Glycols; Quantum Dots; Tellurium

A novel and label-free fluorescence polarization (FP) method for the determination of pyrophosphate (PPi) is developed based on the change in FP signals during fast reversible transformation between CdTe zero-dimensional (0D) nanocrystals (NCs) and one-dimensional (1D) nanorods (NRs) induced by addition of PPi. Under optimum conditions, the FP ratio was linearly proportional to the logarithm of the concentration of PPi between 2.0 × 10(-5) and 1.0 × 10(-9) M with a detection limit of 8.0 × 10(-10) M. The developed method, with high signal selectivity and stability, was successfully applied to the detection of PPi in human urine samples.

Topics: Cadmium Compounds; Diphosphates; Fluorescence Polarization; Humans; Limit of Detection; Nanoparticles; Nanotubes; Tellurium

Since myocardial perfusion imaging (MPI) with conventional sodium iodine (NaI) device has low spatial resolution, there have been some cases in which small structures such as non-transmural myocardial infarction could not be properly detected. The purpose of this study was to evaluate potential usefulness of cadmium-telluride (CdTe) semiconductor detector-based high spatial resolution gamma cameras in detecting myocardial infarction sites, especially non-transmural infarction.. A total of 38 patients (mean age ± SD: 64 ± 21 year) who were clinically diagnosed with acute myocardial infarction were included. Twenty-eight cases of them were with ST segment elevation myocardial infarction (STEMI) and 10 cases with non-ST segment elevation myocardial infarction (NSTEMI). In all patients, myocardial perfusion single photon emission computed tomography images were acquired with Infinia (NaI device) and R1-M (CdTe device), and the images were compared concerning the detectability of acute myocardial infarction sites.. The detection rates of the myocardial infarction site in cases with STEMI were 100% both by NaI and CdTe images. In cases with NSTEMI, detection rate by NaI images was 50%, while that of CdTe images was 100% (p = 0.033). The summed rest score (SRS) value derived from CdTe images was significantly higher than that from NaI images in cases with STEMI [NaI images: 12 (7-18) versus CdTe images: 14 (9-20)] (p < 0.001). SRS derived from CdTe images was significantly higher than that derived from NaI images in cases with NSTEMI [NaI images: 2 (0-5) versus CdTe images: 6 (6-8)] (p = 0.006).. These results indicate that MPI using CdTe-semiconductor device will provide a much more accurate assessment of acute myocardial infarction in comparison to current methods.

Topics: Acute Disease; Aged; Cadmium Compounds; Female; Gamma Cameras; Humans; Male; Middle Aged; Myocardial Infarction; Myocardial Perfusion Imaging; Phantoms, Imaging; Semiconductors; Tellurium; Tomography, Emission-Computed, Single-Photon

Quantum dots (QDs) are recognized as some of the most promising semiconductor nanocrystals in biomedical applications. However, the potential toxicity of QDs has aroused wide public concern. Catalase (CAT) is a common enzyme in animal and plant tissues. For the potential application of QDs in vivo, it is important to investigate the interaction of QDs with CAT. In this work, the effect of N-Acetyl-L-cysteine-Capped CdTe Quantum Dots with fluorescence emission peak at 612 nm (QDs-612) on CAT was investigated by fluorescence, synchronous fluorescence, fluorescence lifetime, ultraviolet-visible (UV-vis) absorption and circular dichroism (CD) techniques. Binding of QDs-612 to CAT caused static quenching of the fluorescence, the change of the secondary structure of CAT and the alteration of the microenvironment of tryptophan residues. The association constants K were determined to be K288K=7.98×10(5)Lmol(-1) and K298K=7.21×10(5)Lmol(-1). The interaction between QDs-612 and CAT was spontaneous with 1:1 stoichiometry approximately. The CAT activity was also inhibited for the bound QDs-612. This work provides direct evidence about enzyme toxicity of QDs-612 to CAT in vitro and establishes a new strategy to investigate the interaction between enzyme and QDs at a molecular level, which is helpful for clarifying the bioactivities of QDs in vivo.

Topics: Acetylcysteine; Animals; Cadmium Compounds; Catalase; Cattle; Circular Dichroism; Kinetics; Protein Binding; Protein Structure, Secondary; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium; Thermodynamics

In this work, using the quenching of fluorescence of thioglycollic acid (TGA)-capped CdTe quantum dots (QDs), a novel method for the determination of kaempferol (KAE) has been developed. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 552nm against the concentration of KAE was observed in the range of 4-44μgmL(-1) with a detection limit (3σ/K) of 0.79μgmL(-1). In addition, the detailed reaction mechanism has also been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption and fluorescence (FL) spectroscopy. The method has been applied for the determination of KAE in pharmaceutical preparations with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.

Topics: Cadmium Compounds; Fluorescent Dyes; Kaempferols; Limit of Detection; Pharmaceutical Preparations; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates

The development of a nanobody-based electrochemiluminescent immunosensor for procalcitonin quantification is described. A highly specific and enhanced sensitivity of target detection was achieved by CdTe quantum dot encapsulated silica nanoparticle-assisted signal amplification.

Topics: Amino Acid Sequence; Biosensing Techniques; Cadmium Compounds; Calcitonin; Calcitonin Gene-Related Peptide; Electrochemical Techniques; Equipment Design; Humans; Immunoassay; Limit of Detection; Luminescent Measurements; Molecular Sequence Data; Nanoparticles; Protein Precursors; Quantum Dots; Silicon Dioxide; Tellurium

The amphoteric drug molecule tetracycline, which contains groups with pKa 3.4-9.9, was used as a template for conjugating molecularly imprinted polymers (MIPs) and as a quencher for CdTe quantum dot (QD) fluorescence. Two MIP-QD composites were synthesized by a sol-gel method using a silicon-based monomer and a monomer linker between the MIP and QD, i.e., tetraethoxylsilane/3-mercaptopropyltriethoxysilane (MPS) and tetraethoxylsilane/3-aminopropyltriethoxysilane (APS). Another MIP-QD composite was synthesized by the chain-growth polymerization of methacrylic acid (MAA) and an allyl mercaptan linker. The prepared MIP-QDs were characterized by FTIR and SEM and utilized at 0.33 mg/mL to determine the tetracycline content in phosphate buffers (pH 7.4, 50mM) through the Perrin and Stern-Volmer models of quenching fluorometry. The Perrin model was applied to tetracycline concentrations of 7.4 μM-0.37 mM for MIP-MPS-QD, 7.4 μM-0.12 mM for MIP-APS-QD, and 7.4 μM-0.10mM for MIP-MAA-QD (R(2)=0.9988, 0.9978, and 0.9931, respectively). The Stern-Volmer model was applied to tetracycline concentrations of 0.12-0.37 mM for MIP-APS-QD (R(2)=0.9983) and 0.10-0.37 mM for MIP-MAA-QD (R(2)=0.9970). The detection limits were 0.45 μM, 0.54 μM, and 0.50 μM for MIP-MPS-QD, MIP-APS-QD, and MIP-MAA-QD, respectively. Equilibrium times, differences between imprinted and nonimprinted polymers, and MIP-QD quenching mechanisms were discussed. Finally, specificity studies demonstrated that MIP-MAA-QD exhibited optimal recoveries of 96% from bovine serum albumin (n=5, RSD=3.6%) and 91% from fetal bovine serum (n=5, RSD=4.8%).

Topics: Acrylates; Animals; Anti-Bacterial Agents; Biosensing Techniques; Cadmium Compounds; Cattle; Fluorescent Dyes; Fluorometry; Limit of Detection; Molecular Imprinting; Phase Transition; Quantum Dots; Serum Albumin, Bovine; Tellurium; Tetracycline

A simple and sensitive method for the detection of cadmium ion was proposed based on the electrochemiluminescence (ECL) of thioglycolic acid capped-CdTe quantum dots (CdTe QDs). The ECL of CdTe QDs was firstly quenched by introduction of S(2)(-) and was restored due to following addition of Cd(2+), on the basis of which, a "turn-on" ECL method for the detection of Cd(2+) was demonstrated. The ECL of CdTe QDs exhibited linear response toward Cd(2+) concentration in the range from 6.3nM to 3.4μM (R=0.999) with a detection limit of 2.1nM. The proposed assay was simple, sensitive, selective, and practicable in real water samples.

Topics: Cadmium; Cadmium Compounds; Electrochemical Techniques; Limit of Detection; Luminescent Measurements; Quantum Dots; Tellurium; Water

We report herein the facile surface-functionalization of one type of biocompatible, oligomeric nanoparticles 1-NPs with NIR-emitting CdTe/CdS QDs and folate for tumor-targeted imaging in vivo. The -NH2 and -SH groups of cysteine residues on the 1-NPs were utilized to covalently conjugate CdTe/CdS QDs and Mal-FA to prepare the hybrid nanoparticles 1-NPs-QDs-FA. As-prepared 1-NPs-QDs-FA showed NIR-fluorescence emission at 734 nm, selective uptake by FR-overexpressing tumor cells in vitro, and selective FR-overexpressing tumor-targeted imaging in vivo. This first example of oligomeric/inorganic hybrid nanoparticles provides people with new type of biomaterials for tumor-targeted imaging with high selectivity.

Topics: Animals; Cadmium Compounds; Diagnostic Imaging; Fluorescence; Folic Acid; Mice, Nude; Nanoparticles; Neoplasms; Optical Imaging; Organ Specificity; Quantum Dots; Spectroscopy, Near-Infrared; Sulfides; Tellurium

Quantum dots (QDs) are one of the most promising nanomaterials, due to their size-dependent characteristics as well as easily controllable size during the synthesis process. They are promising label material and their interaction with biomolecules is of great interest for science. In this study, CdTe QDs were synthesized under optimal conditions for 2 nm size. Characterization and verification of QDs synthesis procedure were done by fluorimetric method and with CE. Afterwards, QDs interaction with chicken genomic DNA and 500 bpDNA fragment was observed employing CE-LIF and gel electrophoresis. Performed interaction relies on possible matching between size of QDs and major groove of the DNA, which is approximately 2.1 nm.

Topics: Animals; Cadmium Compounds; Chickens; DNA; Electrophoresis, Capillary; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Thin-film photovoltaic (PV) technologies have improved significantly recently, and similar improvements are projected into the future, warranting reevaluation of the environmental implications of PV to update and inform policy decisions. By conducting a hybrid life cycle assessment using the most recent manufacturing data and technology roadmaps, we compare present and projected environmental, human health, and natural resource implications of electricity generated from two common thin-film PV technologies-copper indium gallium selenide (CIGS) and cadmium telluride (CdTe)-in the United States (U.S.) to those of the current U.S. electricity mix. We evaluate how the impacts of thin films can be reduced by likely cost-reducing technological changes: (1) module efficiency increases, (2) module dematerialization, (3) changes in upstream energy and materials production, and (4) end-of-life recycling of balance of system (BOS). Results show comparable environmental and resource impacts for CdTe and CIGS. Compared to the U.S. electricity mix in 2010, both perform at least 90% better in 7 of 12 and at least 50% better in 3 of 12 impact categories, with comparable land use, and increased metal depletion unless BOS recycling is ensured. Technological changes, particularly efficiency increases, contribute to 35-80% reductions in all impacts by 2030.

Topics: Cadmium Compounds; Carcinogens; Climate Change; Conservation of Natural Resources; Electricity; Energy-Generating Resources; Environment; Gallium; Gases; Greenhouse Effect; Metals; Selenium; Tellurium; Uncertainty; United States

Lattice-strained CdTe/CdS:Cu quantum dots (QDs) with a widely tunable near-infrared (NIR) fluorescence emission spectrum (700-910 nm) and long lifetime (up to 1 μs) are synthesized. Based on the multiemission and multi-lifetime of the well-defined QDs, NIR-emitting two-dimensional (2D) codes are achieved by embedding as-prepared QDs into agarose beads. This provides a new strategy for fluorescent 2D codes.

Topics: Cadmium Compounds; Light; Materials Testing; Quantum Dots; Spectroscopy, Near-Infrared; Sulfides; Tellurium

In many bioanalytical applications, important molecules such as DNA, proteins, and antibodies are routinely conjugated with fluorescent tags to reach an extraordinary sensitivity of analyses. Semiconductor nanoparticles, quantum dots, have already proved to be suitable components of highly luminescent tags, probes, and sensors with a broad applicability in analytical chemistry. Quantum dots provide high extinction coefficients together with a wide range of excitation wavelengths, size- and composition-tunable emissions, narrow and symmetric emission spectra, good quantum yields, relatively long size-dependent luminescence lifetime, and practically no photobleaching. Most of these properties are superior when compared with conventional organic fluorescent dyes. In this chapter, optimized procedures for the preparation of water-dispersed cadmium telluride (CdTe) quantum dots, conjugating reactions with antibodies, DNA, and macrocycles as well as their analyses by capillary electrophoresis are described. The potential of capillary electrophoresis for fast analyses of nanoparticles, their conjugates with antibodies, and immunocomplexes with targeted antigens is demonstrated on examples.

Topics: Cadmium Compounds; DNA; Electrophoresis, Capillary; Fluorescence Resonance Energy Transfer; Immunoassay; Lasers; Luminescent Measurements; Macrocyclic Compounds; Quantum Dots; Semiconductors; Tellurium; Water

An essential parameter to evaluate the light emission properties of fluorophores is the fluorescence quantum yield, which quantify the conversion efficiency of absorbed photons to emitted photons. We detail here an alternative nonfluorescent method to determine the absolute fluorescence quantum yield of quantum dots (QDs). The method is based in the so-called Thermal Lens Spectroscopy (TLS) technique, which consists on the evaluation of refractive index gradient thermally induced in the fluorescent material by the absorption of light. Aqueous dispersion carboxyl-coated cadmium telluride (CdTe) QDs samples were used to demonstrate the Thermal Lens Spectroscopy technical procedure.

Topics: Cadmium Compounds; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Quantum dots (QDs) have been used as fluorescent probes in biological and medical fields such as bioimaging, bioanalytical, and immunofluorescence assays. For these applications, it is important to characterize the QD-protein bioconjugates. This chapter provides details on a versatile method to confirm quantum dot-protein conjugation including the required materials and instrumentation in order to perform the step-by-step semiquantitative analysis of the bioconjugation efficiency by using fluorescence plate readings. Although the protocols to confirm the QD-protein attachment shown here were developed for CdTe QDs coated with specific ligands and proteins, the principles are the same for other QDs-protein bioconjugates.

Topics: Animals; Cadmium Compounds; Cattle; Humans; Immobilized Proteins; Immunoglobulins; Quantum Dots; Serum Albumin, Bovine; Spectrometry, Fluorescence; Tellurium; Water

A study of the interactions between nanoparticles and living cells is invaluable in understanding the nano-biological effect and the mechanism of cellular endocytosis. Here we describe two methods for the preparation of semiconductor quantum dots with different physiochemical properties. Furthermore, we describe how to study the interaction of the two quantum dots with living HeLa cells and red blood cells with confocal microscopy.

Topics: Cadmium Compounds; Cell Survival; Erythrocytes; HeLa Cells; Humans; Ligands; Microscopy, Confocal; Nanotechnology; Penicillamine; Quantum Dots; Sulfides; Tellurium; Thiomalates; Zinc Compounds

The substrate-overlayer approach has been used to acquire surface enhanced Raman spectra (SERS) during and after electrochemical atomic layer deposition (ECALD) of CdSe, CdTe, and CdS thin films. The collected data suggest that SERS measurements performed with off-resonance (i.e. far from the surface plasmonic wavelength of the underlying SERS substrate) laser excitation do not introduce perturbations to the ECALD processes. Spectra acquired in this way afford rapid insight on the quality of the semiconductor film during the course of an ECALD process. For example, SERS data are used to highlight ECALD conditions that yield crystalline CdSe and CdS films. In contrast, SERS measurements with short wavelength laser excitation show evidence of photoelectrochemical effects that were not germane to the intended ECALD process. Using the semiconductor films prepared by ECALD, the substrate-overlayer SERS approach also affords analysis of semiconductor surface adsorbates. Specifically, Raman spectra of benzenethiol adsorbed onto CdSe, CdTe, and CdS films are detailed. Spectral shifts in the vibronic features of adsorbate bonding suggest subtle differences in substrate-adsorbate interactions, highlighting the sensitivity of this methodology.

Topics: Cadmium Compounds; Electrochemistry; Selenium Compounds; Spectrum Analysis, Raman; Sulfides; Surface Properties; Tellurium

Water-soluble cysteamine (CA) capped CdTe quantum dots (QDs) conjugated with lysozyme binding DNA (LBD) was constructed for luminescent sensing of lysozyme by forming a ternary self-assembly complex. Addition of negatively charged lysozyme binding DNA to the positively charged CA capped CdTe QDs buffer solution (Tris-HCl pH 7.4) could lead to the formation of QDs-LBD complex through electrostatic interactions. Once lysozyme was introduced into the CdTe QDs-LBD system, it could bind specifically with the QDs-LBD complex, resulting in fluorescence emission enhancement of the QDs due to the surface inert of QDs. At a given amount of LBD and CdTe QDs (LBD: QDs=2: 1), the fluorescence intensity enhancement of QDs was linear with lysozyme concentration over the range of 8.9-71.2 nM, with a detection limit of 4.3 nM. Due to the specific binding of LBD with lysozyme, this approach displayed high selectivity for lysozyme recognition. The sensing mechanism was confirmed by DLS and zeta potential measurement, and agarose gel electrophoresis experiment. Furthermore, the proposed CA-capped CdTe QDs-LBD sensor was applied to lysozyme detection in mouse serum and human morning urine samples, which showed high sensitivity and selectivity in the complex biological sample.

Topics: Amino Acids; Animals; Anisotropy; Biosensing Techniques; Cadmium Compounds; Cysteamine; DNA; Electrophoresis, Agar Gel; Fluorescent Dyes; Humans; Limit of Detection; Mice; Muramidase; Nanotechnology; Quantum Dots; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium; Urinalysis

A cross-reactive sensor array using mercaptopropionic acid modified cadmium telluride (CdTe), glutathione modified CdTe, poly(methacrylic acid) modified silver nanoclusters, bovine serum albumin modified gold nanoclusters, rhodamine derivative and calcein blue as fluorescent indicators has been designed for the detection of seven heavy metal ions (Ag(+), Hg(2+), Pb(2+), Cu(2+), Cr(3+), Mn(2+) and Cd(2+)). The discriminatory capacity of the sensor array to different heavy metal ions in different pH solutions has been tested and the results have been analyzed with linear discriminant analysis. Results showed that the sensor array could be used to qualitatively analyze the selected heavy metal ions. The array performance was also evaluated in the identification of known and unknown samples and the preliminary results suggested the promising practicability of the designed sensor assay.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Cattle; Fluoresceins; Fluorescent Dyes; Glutathione; Gold; Hydrogen-Ion Concentration; Ions; Metals, Heavy; Nanoparticles; Nanotechnology; Rhodamines; Serum Albumin, Bovine; Silver; Spectrometry, Fluorescence; Tellurium

Sulfonated magnetic microspheres (PSt-DVB-SNa MPs) have been successfully prepared as adsorbents via an aqueous suspension polymerization of styrene-divinylbenzene and a sulfonation reaction successively. The resulting adsorbents were confirmed by means of Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS) and vibrating sample magnetometer (VSM). The leaching process of CdTe was optimized, and the removal efficiency of Cd and Te from the leaching solution was investigated. The adsorbents could directly remove all cations of Cd and Te from a highly acidic leaching solution of CdTe. The adsorption process for Cd and Te reached equilibrium in a few minutes and this process highly depended on the dosage of adsorbents and the affinity of sulfonate groups with cations. Because of its good adsorption capacity in strong acidic media, high adsorbing rate, and efficient magnetic separation from the solution, PSt-DVB-SNa MPs is expected to be an ideal material for the recycling of CdTe photovoltaic waste.

Topics: Acids; Adsorption; Cadmium Compounds; Electronic Waste; Industrial Waste; Ion Exchange Resins; Kinetics; Magnetics; Microscopy, Electron, Scanning; Microspheres; Particle Size; Semiconductors; Tellurium; Thermodynamics

The worldwide trend in nanoparticle technology toward increasing complexity must be directly linked to more advanced characterization methods of size, shape and related properties, applicable to many different particle systems in science and technology. Available techniques for nanoparticle characterization are predominantly focused on size characterization. However, simultaneous size and shape characterization is still an unresolved major challenge. We demonstrate that analytical ultracentrifugation with a multiwavelength detector is a powerful technique to address multidimensional nanoparticle analysis. Using a high performance optical setup and data acquisition software, information on size, shape anisotropy and optical properties were accessible in one single experiment with unmatched accuracy and resolution. A dynamic rotor speed gradient allowed us to investigate broad distributions on a short time scale and differentiate between gold nanorod species including the precise evaluation of aggregate formation. We report how to distinguish between different species of single-wall carbon nanotubes in just one experiment using the wavelength-dependent sedimentation coefficient distribution without the necessity of time-consuming purification methods. Furthermore, CdTe nanoparticles of different size and optical properties were investigated in a single experiment providing important information on structure-property relations. Thus, multidimensional information on size, density, shape and optical properties of nanoparticulate systems becomes accessible by means of analytical ultracentrifugation equipped with multiwavelength detection.

Topics: Cadmium Compounds; Gold; Limit of Detection; Nanoparticles; Nanotubes; Nanotubes, Carbon; Particle Size; Signal-To-Noise Ratio; Tellurium; Ultracentrifugation

A novel molecular imprinted sensor based on CdTe@SiO2 quantum dots (QDs) was developed for norepinephrine (NE) recognition. The molecularly imprinted polymer (MIP) on the surface of CdTe@SiO2 QDs (CdTe@SiO2@MIP) was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescence spectroscopy. The synthesized nanosensor had a distinguished selectivity and high binding affinity to NE. Under optimal conditions, the relative fluorescence intensity of CdTe@SiO2@MIP linearly decreased with increase of the concentration of NE in the range of 0.04-10 μM. The limit of detection was 8 nM (3σ/K). The proposed method was applied to the analysis of NE in rat plasma, and the result obtained by the method was in good agreement with that assayed by the fluorescence derivatization method. The method developed is simple, fast, and can be applied to the determination of NE in biological samples.

Topics: Cadmium Compounds; Fluorescent Dyes; Limit of Detection; Microscopy, Electron, Transmission; Molecular Imprinting; Norepinephrine; Polymers; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Tellurium

There is an increased use of Quantum Dot (QDs) in biological and biomedical applications, but little is known about their marine ecotoxicology. So, the aim of this study was to investigate the possible immunocytotoxic, cytogenotoxic and genotoxic effects of cadmium telluride QDs (CdTe QDs) on the marine mussel Mytilus galloprovincialis. Mussels were exposed to 10 μg L(-1) of CdTe QDs or to soluble Cd [Cd(NO3)2] for 14 days and Cd accumulation, immunocytotoxicity [hemocyte density, cell viability, lysosomal membrane stability (LMS), differential cell counts (DCC)], cytogenotoxicity (micronucleus test and nuclear abnormalities assay) and genotoxicity (comet assay) were analyzed. Results show that in vivo exposure to QDs, Cd is accumulated in mussel soft tissues and hemolymph and induce immunotoxic effects mediated by a decrease in LMS, changes in DCC, as well as genotoxicity (DNA damage). However, QDs do not induce significant changes in hemocytes density, cell viability and cytogenetic parameters in opposition to Cd(2+). Soluble Cd is the most cytotoxic and cytogenotoxic form on Mytilus hemocytes due to a higher accumulation of Cd in tissues. Results indicate that immunotoxicity and genotoxicity of CdTe QDs and Cd(2+) are mediated by different modes of action and show that Mytilus hemocytes are important targets for in vivo QDs toxicity.

Topics: Animals; Cadmium Compounds; Environmental Exposure; Hemocytes; Mytilus; Quantum Dots; Stress, Physiological; Tellurium; Toxicity Tests

In this paper, we report microwave-assisted, one-stage synthesis of high-quality functionalized water-soluble cadmium telluride (CdTe) quantum dots (QDs). By selecting sodium tellurite as the Te source, cadmium chloride as the Cd source, mercaptosuccinic acid (MSA) as the capping agent, and a borate-acetic acid buffer solution with a pH range of 5-8, CdTe nanocrystals with four colors (blue to orange) were conveniently prepared at 100 °C under microwave irradiation in less than one hour (reaction time: 10-60 min). The influence of parameters such as the pH, Cd:Te molar ratio, and reaction time on the emission range and quantum yield percentage (QY%) was investigated. The structures and compositions of the prepared CdTe QDs were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, selective area electron diffraction, and X-ray powder diffraction experiments. The formation mechanism of the QDs is discussed in this paper. Furthermore, AS1141-aptamer-conjugated CdTe QDs in the U87MG glioblastoma cell line were assessed with a fluorescence microscope. The obtained results showed that the best conditions for obtaining a high QY of approximately 87% are a pH of 6, a Cd:Te molar ratio of 5:1, and a 30-min reaction time at 100 °C under microwave irradiation. The results showed that AS1141-aptamer-conjugated CdTe QDs could enter tumor cells efficiently. It could be concluded that a facile high-fluorescence-strength QD conjugated with a DNA aptamer, AS1411, which can recognize the extracellular matrix protein nucleolin, can specifically target U87MG human glioblastoma cells. The qualified AS1411-aptamer-conjugated QDs prepared in this study showed excellent capabilities as nanoprobes for cancer targeting and molecular imaging.

Topics: Aptamers, Nucleotide; Cadmium Compounds; Cell Line, Tumor; Fluorescence; Humans; Molecular Imaging; Molecular Probes; Molecular Structure; Neoplasms; Oligodeoxyribonucleotides; Quantum Dots; Staining and Labeling; Tellurium

Tellurium-based devices, such as photovoltaic (PV) modules and thermoelectric generators, are expected to play an increasing role in renewable energy technologies. Tellurium, however, is one of the scarcest elements in the earth's crust, and current production and recycling methods are inefficient and use toxic chemicals. This study demonstrates an alternative, bacterially mediated tellurium recovery process.. We show that the hydrothermal vent microbe Pseudoalteromonas sp. strain EPR3 can convert tellurium from a wide variety of compounds, industrial sources and devices into metallic tellurium and a gaseous tellurium species. These compounds include metallic tellurium (Te(0)), tellurite (TeO3(2-)), copper autoclave slime, tellurium dioxide (TeO2), tellurium-based PV material (cadmium telluride, CdTe) and tellurium-based thermoelectric material (bismuth telluride, Bi2Te3). Experimentally, this was achieved by incubating these tellurium sources with the EPR3 in both solid and liquid media.. Despite the fact that many of these tellurium compounds are considered insoluble in aqueous solution, they can nonetheless be transformed by EPR3, suggesting the existence of a steady state soluble tellurium concentration during tellurium transformation.. These experiments provide insights into the processes of tellurium precipitation and volatilization by bacteria, and their implications on tellurium production and recycling.

Topics: Bismuth; Cadmium Compounds; Pseudoalteromonas; Tellurium

There has been great progress in the development of fluorescence biosensors based on quantum dots (QDs) for the detection of lead ions. However, most methods are detecting lead ions in aqueous solution rather than in human serum due to the influence of protein autofluorescence in serum excited by visible light. Thus, we developed a novel fluorescence resonance energy transfer (FRET) biosensor by choosing the upconversion NaYF4:Yb(3+)/Tm(3+) nanoparticles as the energy donor and the CdTe QDs as the energy acceptor for lead ion detection. It is the first near infrared (NIR)-excited fluorescent probe for determination of lead ions in serum that is capable of overcoming self-luminescence from serum excitation with visible light. The sensor also shows high selectivity, a low detection limit (80 nm) and good linear Stern-Volmer characteristics (R = 0.996), both in the buffer and serum. This biosensor has great potential for versatile applications in lead ion detection in biological and analytical fields.

Topics: Biosensing Techniques; Cadmium Compounds; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; Gold; Humans; Ions; Lead; Light; Limit of Detection; Microscopy, Electron, Transmission; Nanotechnology; Quantum Dots; Spectroscopy, Near-Infrared; Static Electricity; Tellurium

In this study, magnetic-encoded fluorescent (CdTe/Fe3O4)@SiO2 multifunctional nanospheres were constructed by adjusting the initial concentration of Fe3O4 in a fabrication process based on reverse microemulsion. The resultant multifunctional nanospheres were characterized by transmission electron microscopy, X-ray diffraction measurements, fluorescence spectrophotometry, and vibrating sample magnetometry. They showed good fluorescence properties, gradient magnetic susceptibility (weak, moderate, and strong), and easy biofunctionalization for biomolecules, such as immunoglobulin G (IgG), protein, and antibody. Then the capture efficiency of the (CdTe/Fe3O4)@SiO2 nanospheres were investigated by using the fluorophore-labeled IgG-conjugated nanospheres as a model. Further studies demonstrated the ability of these (CdTe/Fe3O4)@SiO2 multifunctional nanospheres to accomplish sequentially magnetic separation, capture, and fluorescent detection for each corresponding antigen of CA125, AFP, and CEA with a detection limit of 20 KU/L, 10 ng/mL, and 5 ng/mL, respectively, from a mixed sample under a certain external magnetic field within a few minutes. The strategy of combining magnetic-encoding-based separation and fluorescence-based detection proposed in this study shows great potential to achieve easy, rapid, economical, and near-simultaneous multicomponent separation and analysis for a variety of targets such as drugs, biomarkers, pathogens, and so on.

Topics: alpha-Fetoproteins; CA-125 Antigen; Cadmium Compounds; Carcinoembryonic Antigen; Emulsions; Ferrosoferric Oxide; Fluorescent Dyes; Humans; Immunoconjugates; Immunoglobulin G; Limit of Detection; Magnets; Membrane Proteins; Nanospheres; Silicon Dioxide; Solutions; Spectrometry, Fluorescence; Tellurium

Although various strategies have been reported for double-stranded DNA (DNA) detection, development of a time-saving, specific, and regeneratable fluorescence sensing platform still remains a desired goal. In this study, we proposed a new DNA detection method that relies on an "off-on" switch of a regenerated fluorescence biosensor based on an electron transfer mechanism from glutathione (GSH)-capped CdTe quantum dots (QDs) to nile blue (NB). Initially, the high fluorescence of GSH-capped CdTe QDs could be effectively quenched by NB due to the binding of NB to the GSH on the surface of the QDs and the electron transfer from the photoexcited GSH-capped CdTe QDs to NB. Then, the high affinity of DNA to NB enabled the NB to be dissociated from the surface of GSH-capped CdTe QDs to form a more stable complex with DNA and suppress the electron transfer process between GSH-capped CdTe QDs and NB, thereby restoring the fluorescence of NB surface modified GSH-capped CdTe QDs (QDs-NB). In addition, we have testified the regenerability of the proposed DNA senor. The corresponding result shows that this DNA sensor is stable for two reuses. This fluorescence "off-on" signal was sensitive to the concentration of DNA in the range from 0.0092 to 25.0 μg mL(-1) with a good correlation coefficient of 0.9989, and the detection limit (3σ/S) was 2.78 ng mL(-1). To further investigate for perfect analysis performance, the developed biosensor was applied for the determination of DNA in human fresh serum samples with satisfactory results.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electron Transport; Glutathione; Microscopy, Electron, Transmission; Oxazines; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

Nanometer-sized semiconductor particles (CdTe) were used as an inorganic matrix for the laser desorption/ionization mass spectrometry of fatty acids. The excitation power dependence of the peak intensity of stearic acid (Ste), [Ste - H](-), was observed, and it was proportional to the square of the excitation power. The peak intensity of [Ste - H](-) decreased by addition of a hole scavenger (KSCN). It was understood that the ionization of fatty acids were due to the biexciton Auger recombination and electron ejection from CdTe. CdTe were then loaded on zeolite surface. The peak intensity enhancement of the deprotonated ion of fatty acid were observed. This phenomenon was explained by measuring the carrier lifetime for Auger recombination in CdTe. In addition, reproducibility of fatty acid ions was highly improved reflecting homogeneous distribution of CdTe on zeolite surface. CdTe/HM20 was successfully applied to the quantitative analysis of Ste in human serum by isotope dilution using (13)C18-Ste. The concentration of Ste in human serum samples was estimated to be 76.62 mg/kg with the standard deviation (SD) of 2.37 mg/kg.

Topics: Cadmium Compounds; Fatty Acids, Nonesterified; Humans; Nanoparticles; Spectrometry, Fluorescence; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tellurium; Zeolites

The electronic and photoconductive characteristics of CdTe nanowire-based field effect transistors were studied systematically. The electrical characterization of a single CdTe nanowire FET verifies p-type behavior. The CdTe NW FETs respond to visible-near infrared (400-800 nm) incident light with a fast, reversible and stable response characterized by a high responsivity (81 A W(-1)), photoconductive gain (∼2.5 × 10(4)%) and reasonable response and decay times (0.7 s and 1 s, respectively). These results substantiate the potential of CdTe nanowire-based photodetectors in optoelectronic applications.

Topics: Cadmium Compounds; Electric Conductivity; Infrared Rays; Light; Nanowires; Tellurium; Transistors, Electronic

Sensitive and rapid detection of multiple analytes and the collection of components from complex samples are important in fields ranging from bioassays/chemical assays, clinical diagnosis, to environmental monitoring. A convenient strategy for creating magnetically encoded luminescent CdTe@SiO2 @n Fe3 O4 composite nanoparticles, by using a layer-by-layer self-assembly approach based on electrostatic interactions, is described. Silica-coated CdTe quantum dots (CdTe@SiO2 ) serve as core templates for the deposition of alternating layers of Fe3 O4 magnetic nanoparticles and poly(dimethyldiallyl ammonium chloride), to construct CdTe@SiO2 @n Fe3 O4 (n=1, 2, 3, …︁) composite nanoparticles with a defined number (n) of Fe3 O4 layers. Composite nanoparticles were characterized by zeta-potential analysis, fluorescence spectroscopy, vibrating sample magnetometry, and transmission electron microscopy, which showed that the CdTe@SiO2 @n Fe3 O4 composite nanoparticles exhibited excellent luminescence properties coupled with well-defined magnetic responses. To demonstrate the utility of these magnetically encoded nanoparticles for near-simultaneous detection and separation of multiple components from complex samples, three different fluorescently labeled IgG proteins, as model targets, were identified and collected from a mixture by using the CdTe@SiO2 @n Fe3 O4 nanoparticles.

Topics: Cadmium Compounds; Ferric Compounds; Luminescence; Luminescent Measurements; Magnetics; Nanocomposites; Quantum Dots; Silicon Dioxide; Tellurium

A TiO2/CdS:Mn hybrid structure cosensitized with two different sizes of CdTe quantum dots (QDs) was designed to develop a novel and ultrasensitive photoelectrochemical DNA assay. In this protocol, TiO2/CdS:Mn hybrid structure was prepared by successive adsorption and reaction of Cd(2+)/Mn(2+) and S(2-) ions on the surface of TiO2 film and then was employed as matrix for immobilization of hairpin DNA probe, whereas large-sized CdTe-COOH QDs and small-sized CdTe-NH2 QDs as signal amplification elements were successively labeled on the terminal of hairpin DNA probe. The target DNA detection was based upon the photocurrent change originated from conformation change of the hairpin DNA probe after hybridization with target DNA. In the absence of target DNA, the immobilized DNA probe was in the hairpin form and the anchored different sizes of CdTe-COOH and CdTe-NH2 QDs were close to the TiO2/CdS:Mn electrode surface, which led to a very strong photocurrent intensity because of the formation of the cosensitized structure. However, in the presence of target DNA, the hairpin DNA probe hybridized with target DNA and changed into a more rigid, rodlike double helix, which forced the multianchored CdTe QDs away from the TiO2/CdS:Mn electrode surface, resulting in significantly decreased photocurrent intensity because of the vanished cosensitization effect. By using this cosensitization signal amplification strategy, the proposed DNA assay could offer an ultrasensitive and specific detection of DNA down to 27 aM, and it opened up a new promising platform to detect various DNA targets at ultralow levels for early diagnoses of different diseases.

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Electrochemical Techniques; Limit of Detection; Manganese; Microscopy, Electron, Transmission; Photochemical Processes; Quantum Dots; Sulfides; Tellurium; Titanium

A magnetic molecularly imprinted fluorescent sensor for the sensitive and convenient determination of ciprofloxacin or norfloxacin in human urine was synthesized and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, ultraviolet/visible spectroscopy, and fluorescence spectroscopy. Both cadmium telluride quantum dots and ferroferric oxide nanoparticles are introduced into the polymer for the rapid separation and detection of the target molecules. The synthesized molecularly imprinted polymers were applied to detect ciprofloxacin or its structural analog norfloxacin in human urine with the detection limit 130 ng/mL. A computational study was developed to evaluate the template-monomer geometry and interaction energy in the polymerization mixture to determine the reaction molar ratio of the template and monomer molecules.

Topics: Cadmium Compounds; Ciprofloxacin; Ferric Compounds; Fluorescence; Fluorescent Dyes; Humans; Magnetic Phenomena; Molecular Dynamics Simulation; Molecular Imprinting; Molecular Structure; Nanospheres; Norfloxacin; Particle Size; Polymers; Quantum Dots; Silicon Dioxide; Surface Properties; Tellurium

Under the two-photon excitation, upconversion luminescent "INHIBIT" and "OR" logic gates of water-dispersed CdTe quantum dots (QDs) were constituted by conjugating the QDs with dopamine. This facilitated the development of a novel QDs-based upconversion luminescent probe for efficient turn-on sensing of glutathione.

Topics: Biosensing Techniques; Cadmium Compounds; Computers, Molecular; Dopamine; Glutathione; Logic; Luminescent Measurements; Quantum Dots; Tellurium

Nanoparticles (NPs) are becoming increasingly widespread in the environment. Free cadmium ions released from commonly used NPs under ultraviolet-B (UV-B) radiation are potentially toxic to living organisms. With increasing levels of UV-B radiation at the Earth's surface due to the depletion of the ozone layer, the potential additive effect of NPs and UV-B radiation on plants is of concern. In this study, we investigated the synergistic effect of CdTe quantum dots (CdTe-QDs), a common form of NP, and UV-B radiation on wheat seedlings. Graded doses of CdTe-QDs and UV-B radiation were tested, either alone or in combination, based on physical characteristics of 5-day-old seedlings. Treatments of wheat seedlings with either CdTe-QDs (200 mg/L) or UV-B radiation (10 KJ/m(2)/d) induced the activation of wheat antioxidant enzymes. CdTe-QDs accumulation in plant root cells resulted in programmed cell death as detected by DNA laddering. CdTe-QDs and UV-B radiation inhibited root and shoot growth, respectively. Additive inhibitory effects were observed in the combined treatment group. This research described the effects of UV-B and CdTe-QDs on plant growth. Furthermore, the finding that CdTe-QDs accumulate during the life cycle of plants highlights the need for sustained assessments of these interactions.

Topics: Antioxidants; Apoptosis; Cadmium Compounds; Oxidoreductases; Plant Proteins; Quantum Dots; Seedlings; Tellurium; Triticum; Ultraviolet Rays

Hybrid SiO2-coated CdTe/CdSe quantum dots (QDs) were prepared using CdTe/CdSe QDs prepared by hydrothermal synthesis. A CdSe interlayer made CdTe/CdSe cores with unique type II heterostructures. The hybrid SiO2-coated CdTe/CdSe QDs revealed excellent photoluminescence (PL) properties compared with hybrid SiO2-coated CdTe QDs. Because of the existence of spatial separations of carriers in the type II CdTe/CdSe core/shell QDs, the hybrid QDs had a relatively extended PL lifetime and high stability in phosphate-buffered saline buffer solutions. This is ascribed to the unique components and stable surface state of hybrid SiO2-coated CdTe/CdSe QDs. During the stabilization test in phosphate-buffered saline buffer solutions, both static and dynamic quenching occurred. The quenching mechanism of the hybrid QDs was not suited with the Stern–Volmer equation. However, the relative stable surface of CdTe/CdSe QDs resulted in lower degradation and relative high PL quantum yields compared with hybrid SiO2-coated CdTe QDs. As a result, hybrid SiO2-coated CdTe/CdSe QDs can be used in bioapplications.

Topics: Cadmium Compounds; Luminescence; Particle Size; Photochemical Processes; Quantum Dots; Selenium Compounds; Silicon Dioxide; Surface Properties; Tellurium

CdTe nanocrystals capped by cysteamine were synthesized to study Cr(V)-induced genotoxicity. On the surface of TiO2 thin films, the stepwise process of DNA breakage induced by Cr(V)-GSH complexes was vividly observed by using CdTe-DNA self-assembled fluorescent probes; in acetate buffer solution, an analytical method was developed to detect Cr(V)-induced genotoxicity with CdTe fluorescent probes.

Topics: Animals; Cadmium Compounds; Cattle; Chromates; DNA; DNA Fragmentation; Fluorescent Dyes; Glutathione; Microscopy, Fluorescence; Mutagens; Nanoparticles; Tellurium

The development of a rapid, label free, cost effective and highly efficient sensor for DNA detection is of great importance in disease diagnosis. Herein, we have reported a new hybrid fluorescent probe based on a cationic curcumin-tryptophan complex and water soluble mercapto succinic acid (MSA) capped CdTe quantum dots (QDs) for the detection of double stranded DNA (ds DNA) molecules. The cationic curcumin-tryptophan complex (CT) directly interacts with negatively charged MSA capped quantum dots via electrostatic coordination, resulting in photoluminescence (PL) quenching of QDs via the Photoinduced Electron Transfer (PET) process. Further, addition of ds DNA results in restoration of PL, as CT would intercalate between DNA strands. Thus, this process can be utilized for selective sensing of ds DNA via fluorescence measurements. Under optimized experimental conditions, the PL quenching efficiency of QDs is found to be 99.4% in the presence of 0.31 × 10(-9) M CT. Interestingly, the regain in PL intensity of QD-CT is found to be 99.28% in the presence of 1 × 10(-8) M ds DNA. The detection limit for ds DNA with the developed sensing probe is 1.4 × 10(-10) M. Furthermore, the probe is found to be highly sensitive towards bacterial DNA isolated from Streptomyces sanglieri with a detection limit of 1.7 × 10(-6) M. The present work will provide a new insight into preparation of bio-inspired hybrid materials as efficient sensors for disease diagnosis and agricultural development.

Topics: Cadmium Compounds; Curcumin; DNA, Bacterial; Electron Transport; Fluorescent Dyes; Intercalating Agents; Limit of Detection; Quantum Dots; Soil Microbiology; Spectrometry, Fluorescence; Streptomyces; Tellurium; Tryptophan

We describe the use of cadmium telluride quantum dots (CdTe QDs) as antennas for the photosensitization of nitric oxide release from a ruthenium nitrosyl complex with visible light excitation. The CdTe QDs were capped with mercaptopropionic acid to make them water-soluble, and the ruthenium nitrosyl complex was cis-[Ru(NO)(4-ampy)(bpy)2](3+) (Ru-NO; bpy is 2,2'-bipyridine, and 4-ampy is 4-aminopyridine). Solutions of these two components demonstrated concentration-dependent quenching of the QD photoluminescence (PL) as well as photoinduced release of NO from Ru-NO when irradiated by 530 nm light. A NO release enhancement of ∼8 times resulting from this association was observed under longer wavelength excitation in visible light range. The dynamics of the quenching determined by both PL and transient absorption measurements were probed by ultrafast flash photolysis. A charge transfer mechanism is proposed to explain the quenching of the QD excited states as well as the photosensitized release of NO from Ru-NO.

Topics: Cadmium Compounds; Nitrogen Oxides; Photochemical Processes; Quantum Dots; Ruthenium; Tellurium

While spectral CT using single photon counting detector has shown a number of advantages in diagnostic imaging, knowledge of the detector response function of an energy-resolved detector is needed to correct the signal bias and reconstruct the image more accurately.. The objective of this paper is to study the photo counting detector response function using laboratory sources, and investigate the signal bias correction method.. Our approach is to model the detector response function over the entire diagnostic energy range (20 keV

Topics: Cadmium Compounds; Calibration; Models, Theoretical; Tellurium; Tomography, Emission-Computed, Single-Photon

An ultrasensitive photoelectrochemical sandwich immunoassay was developed to detect matrix metalloproteinase-2 (MMP-2, antigen, Ag) based on CdS:Mn/CdTe cosensitized TiO2 nanotubes (TiO2-NTs) and signal amplification of SiO2@Ab2 conjugates. Specifically, the TiO2-NTs electrode was first deposited with CdS:Mn by successive ionic layer adsorption and reaction technique and then further coated with CdTe quantum dots (QDs) via the layer-by-layer method, forming TiO2-NTs/CdS:Mn/CdTe cosensitized structure, which was employed as a matrix to immobilize capture MMP-2 antibodies (Ab1); whereas, SiO2 nanoparticles were coated with signal MMP-2 antibodies (Ab2) to form SiO2@Ab2 conjugates, which were used as signal amplification elements via the specific antibody-antigen immunoreaction between Ag and Ab2. The ultrahigh sensitivity of this immunoassay derived from the two major reasons as below. First, the TiO2-NTs/CdS:Mn/CdTe cosensitized structure could adequately absorb the light energy, dramatically promote electron transfer, and effectively inhibit the electron-hole recombination, resulting in significantly enhanced photocurrent intensity of the sensing electrode. However, in the presence of target Ag, the immobilized SiO2@Ab2 conjugates could evidently increase the steric hindrance of the sensing electrode and effectively depress the electron transfer, leading to obviously decreased photocurrent intensity. Accordingly, the well-designed photoelectrochemical immunoassay exhibited a low detection limit of 3.6 fg/mL and a wide linear range from 10 fg/mL to 500 pg/mL for target Ag detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising platform for the detection of other important biomarkers.

Topics: Cadmium Compounds; Immunoassay; Limit of Detection; Manganese; Matrix Metalloproteinase 2; Photochemical Processes; Selenium Compounds; Silicon Dioxide; Tellurium

Most semiconductor nanoparticles used in biomedical applications are made of heavy metals and involve synthetic methods that require organic solvents and high temperatures. This issue makes the development of water-soluble nanoparticles with lower toxicity a major topic of interest. In a previous work our group described a biomimetic method for the aqueous synthesis of CdTe-GSH Quantum Dots (QDs) using biomolecules present in cells as reducing and stabilizing agents. This protocol produces nanoparticles with good fluorescent properties and less toxicity than those synthesized by regular chemical methods. Nevertheless, biomimetic CdTe-GSH nanoparticles still display some toxicity, so it is important to know in detail the effects of these semiconductor nanoparticles on cells, their levels of toxicity and the strategies that cells develop to overcome it.. In this work, the response of E. coli exposed to different sized-CdTe-GSH QDs synthesized by a biomimetic protocol was evaluated through transcriptomic, biochemical, microbiological and genetic approaches. It was determined that: i) red QDs (5 nm) display higher toxicity than green (3 nm), ii) QDs mainly induce expression of genes involved with Cd+2 stress (zntA and znuA) and tellurium does not contribute significantly to QDs-mediated toxicity since cells incorporate low levels of Te, iii) red QDs also induce genes related to oxidative stress response and membrane proteins, iv) Cd2+ release is higher in red QDs, and v) QDs render the cells more sensitive to polymyxin B.. Based on the results obtained in this work, a general model of CdTe-GSH QDs toxicity in E. coli is proposed. Results indicate that bacterial toxicity of QDs is mainly associated with cadmium release, oxidative stress and loss of membrane integrity. The higher toxicity of red QDs is most probably due to higher cadmium content and release from the nanoparticle as compared to green QDs. Moreover, QDs-treated cells become more sensitive to polymyxin B making these biomimetic QDs candidates for adjuvant therapies against bacterial infections.

Topics: Anti-Bacterial Agents; Biomimetic Materials; Cadmium Compounds; Cell Wall; Escherichia coli; Glutathione; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Quantum Dots; Reactive Oxygen Species; Tellurium; Transcriptome

Using the intrinsic toxicity of nanomaterials for anticancer therapy is an emerging concept. In this work, we discovered that CdTe/CdS quantum dots, when coated with lipids (QD-LC) instead of popular liposomes, polymers, or dendrimers, demonstrated extraordinarily high specificity for cancer cells, which was due to the difference in the macropinocytosis uptake pathways of QD-LC between the cancer cells and the normal cells. QD-LC-induced HepG2 cell apoptosis was concomitant with the activation of the JNK/caspase-3 signaling pathway. Moreover, QD-LC treatment resulted in a delay in the latent period for microtumor formation of mouse hepatocarcinoma H22 cells and inhibited tumor growth, with a reduction of 53.2% in tumor volume without toxicity in major organs after intratumoral administrations to tumor-bearing mice. Our results demonstrate that QD-LC could be a very promising theranostic agent against liver cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cadmium Compounds; Cell Survival; Endocytosis; Hep G2 Cells; Humans; Lipids; Liver Neoplasms; Male; Mice; Mice, Inbred ICR; Quantum Dots; Selenium Compounds; Tellurium

Energy resolved photon-counting detectors could achieve more than one spectral measurement. The goal of this study is to investigate, with experiment, the ability to decompose five materials using energy discriminating detectors and multiple discriminant analysis (MDA). A small field-of-view multi-energy CT system was built. Linear attenuation coefficient was considered as features of multiple energy CT. MDA was used to decompose five materials with six measurements of the energy dependent linear attenuation coefficients. The results of the experimental study showed that a CT system based on CdTe detectors with MDA can be used to decompose five materials.

Topics: Cadmium Compounds; Discriminant Analysis; Image Processing, Computer-Assisted; Tellurium; Tomography, X-Ray Computed

An X-ray spectrum measured with CdTe detector has to be corrected with response function, because the spectrum is composed of full energy peaks (FEP) and escape peaks (EP). Recently, various simulation codes were developed, and using them the response functions can be calculated easily. The aim of this study is to propose a new method for measuring the response function and to compare it with the calculated value by the Monte Carlo simulation code. In this study, characteristic X-rays were used for measuring the response function. These X-rays were produced by the irradiation of diagnostic X-rays with metallic atoms. In the measured spectrum, there was a background contamination, which was caused by the Compton scattering of the irradiated X-ray in the sample material. Therefore, we thought of a new experimental methodology to reduce this background. The experimentally derived spectrum was analyzed and then the ratios of EP divided by FEP (EP/FEP) were calculated to compare the simulated values. In this article, we showed the property of the measured response functions and the analysis accuracy of the EP/FEP, and we indicated that the values calculated by Monte Carlo simulation code could be evaluated by using our method.

Topics: Cadmium Compounds; Image Processing, Computer-Assisted; Monte Carlo Method; Radiography; Spectrum Analysis; Tellurium

Highly luminescent CdTe quantum dots (QDs) were synthesized through a co-precipitation route in aqueous salt solutions using different thiols as stabilizers. The synthetic procedure was simple, efficient, and stable. It could also allow controlling the emission wavelength by varying the experimental conditions such as reaction time and pH values. The strong luminescence of the QDs was observed under UV-excitation and emission colors could be adjusted. The interaction between CdTe QDs and triethylenetetramine dihydrochloride (TETA) which is a candidate treatment for diabetic cardiovascular complication was investigated by fluorescence spectroscopy. Based on the quenching effect on CdTe photoluminescence intensity by TETA, a simple assay system for analyzing the content of TETA in aqueous samples was developed. The linearity was maintained in the range of 0.2 μM to 1.2 μM (R2 = 0.994) with a limit of detection (LOD; S/N = 3) at 28 nM. The results showed that CdTe QDs capped with diverse thiols has a potential for the quantitative analysis of TETA in urine samples.

Topics: Cadmium Compounds; Hydrogen-Ion Concentration; Kinetics; Nanotechnology; Optical Phenomena; Quantum Dots; Sulfhydryl Compounds; Surface-Active Agents; Tellurium; Thioglycolates; Trientine

Highly luminescent water soluble CdTe quantum dots (QDs) were synthesized and conjugated with anti-HbA1c antibody to generate specific nanobioprobe. A sandwich immunoassay model was employed using capture HbA1c antibody as a specific receptor molecule and the QD-labeled secondary antibody as a dual (fluorescence cum electrochemical) tracer to quantify the concentration of HbA1c. A linear increase in current was observed for HbA1c analytical standards with a R(2) value of 0.990 and coefficient of variance ~5%. A comparison between HPLC and dual immunoassay for clinical samples showed a correlation coefficient of 89% and 96% for fluorescence and electrochemical detection methods respectively. The QD-based immunoassay shows great promise for rapid reproducible and cost effective analysis of HbA1c in clinical samples.

Topics: Adult; Biomarkers; Cadmium Compounds; Diabetes Mellitus; Electrochemical Techniques; Glycated Hemoglobin; Humans; Immunoassay; Immunoconjugates; Luminescent Agents; Quantum Dots; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium

To develop a silicon (Si) and cadmium telluride (CdTe) imaging Compton camera for biomedical application on the basis of technologies used for astrophysical observation and to test its capacity to perform three-dimensional (3D) imaging.. All animal experiments were performed according to the Animal Care and Experimentation Committee (Gunma University, Maebashi, Japan). Flourine 18 fluorodeoxyglucose (FDG), iodine 131 ((131)I) methylnorcholestenol, and gallium 67 ((67)Ga) citrate, separately compacted into micro tubes, were inserted subcutaneously into a Wistar rat, and the distribution of the radioisotope compounds was determined with 3D imaging by using the Compton camera after the rat was sacrificed (ex vivo model). In a separate experiment, indium 111((111)In) chloride and (131)I-methylnorcholestenol were injected into a rat intravenously, and copper 64 ((64)Cu) chloride was administered into the stomach orally just before imaging. The isotope distributions were determined with 3D imaging after sacrifice by means of the list-mode-expectation-maximizing-maximum-likelihood method.. The Si/CdTe Compton camera demonstrated its 3D multinuclear imaging capability by separating out the distributions of FDG, (131)I-methylnorcholestenol, and (67)Ga-citrate clearly in a test-tube-implanted ex vivo model. In the more physiologic model with tail vein injection prior to sacrifice, the distributions of (131)I-methylnorcholestenol and (64)Cu-chloride were demonstrated with 3D imaging, and the difference in distribution of the two isotopes was successfully imaged although the accumulation on the image of (111)In-chloride was difficult to visualize because of blurring at the low-energy region.. The Si/CdTe Compton camera clearly resolved the distribution of multiple isotopes in 3D imaging and simultaneously in the ex vivo model.

Topics: Animals; Cadmium Compounds; Citrates; Copper; Equipment Design; Fluorodeoxyglucose F18; Gallium; Gallium Radioisotopes; Gamma Cameras; Imaging, Three-Dimensional; Indium; Iodine Radioisotopes; Pets; Radiopharmaceuticals; Rats; Rats, Wistar; Silicon; Tellurium; Tomography, Emission-Computed, Single-Photon

A biomimetic quantum dot synthesis-based strategy for ultrasensitive label-free detection of protease activities is reported. A dithiol peptide substrate can be activated by the protease through cleavage to form monothiol peptides, which then triggers QD growth and generates a photoluminescence signal readout. As low as 0.8 nM trypsin can be detected directly in buffer and serum and 4 pM trypsin can be detected via trypsinogen amplification with high signal to background ratios.

Topics: Animals; Biomimetics; Cadmium Compounds; Cattle; Fluorescent Dyes; Luminescence; Nanoparticles; Peptide Hydrolases; Peptides; Quantum Dots; Staining and Labeling; Tellurium; Trypsin

Quantum dots (QDs) have strong adsorption capacity; therefore, their potential toxicity of the facilitated transport of other trace toxic pollutants when they co-exist to aquatic organisms has become a hot research topic. The lab study was performed to determine the developmental toxicities to the zebrafish after exposed to the combined pollution of Cadmium-telluride (CdTe) QDs and copper ion (Cu(2+)) compared to the single exposure. Our findings for the first time revealed that: 1) CdTe QDs facilitated the accumulation of Cu(2+) in zebrafish, 2) the higher mortality, lower hatch rate, and more malformations can be clearly observed, 3) the diverse vascular hyperplasia, turbulence, and bifurcation of the exposed FLI-1 transgenic zebrafish larvae appeared together, 4) the synergistic effects played more important role during joint exposure. These observations provide a basic understanding of CdTe QDs and Cu(2+) joint toxicity to aquatic organisms.

Topics: Animals; Cadmium Compounds; Copper; Quantum Dots; Risk Assessment; Tellurium; Toxicity Tests; Water Pollutants, Chemical; Zebrafish

A novel strategy for immobilization of CdTe quantum dots (QDs) onto amino functionalized solid supports was developed. QDs capped with compounds holding an amino group were covalently bonded to the substrate under mild reaction conditions, exhibiting great stability and strong luminescence.

Topics: Amines; Cadmium Compounds; Cysteine; Glutathione; Microscopy, Fluorescence; Quantum Dots; Spectroscopy, Fourier Transform Infrared; Surface Properties; Tellurium

A new method based on the use of highly fluorescent water-soluble cadmium telluride (CdTe) quantum dots (QDs) capped with mercaptosuccinic acid (MSA) was explored to develop latent fingerprints. After optimized the effectiveness of QDs method contains pH value and developing time, super fast detection was achieved. Excellent fingerprint images were obtained in 1-3s after immersed the latent fingerprints into quantum dots solution on various non-porous surfaces, i.e. adhesive tape, transparent tape, aluminum foil and stainless steel. High sensitivity of the new latent fingerprints develop method was obtained by developing the fingerprints pressed on aluminum foil successively with the same finger. Compared with methyl violet and rhodamine 6G, the MSA-CdTe QDs showed the higher develop speed and fingerprint image quality. Clear image can be maintained for months by extending exposure time of CCD camera, storing fingerprints in a low temperature condition and secondary development.

Topics: Cadmium Compounds; Dermatoglyphics; Fluorescent Dyes; Gentian Violet; Humans; Hydrogen-Ion Concentration; Male; Photography; Quantum Dots; Rhodamines; Solubility; Surface Properties; Tellurium; Thiomalates; Ultraviolet Rays; Water

We report wavelength-dependent enormous enhancement of the nonlinear refractive index of wild-type bacteriorhodopsin in the presence of semiconductor quantum dots. The effect is strongest in the region just below the absorption edge of both constituents of this hybrid material and in samples that show strong Förster resonance energy transfer. We show that enhancements of up to 4000% can be achieved by controlled engineering of the hybrid structure involving variations of the molar ratio of the constituents. This new hybrid material with exceptional nonlinear properties will have numerous photonic and optoelectronic applications employing its photochromic, energy transfer, and conversion properties.

Topics: Amino Acid Substitution; Bacteriorhodopsins; Cadmium Compounds; Fluorescence Resonance Energy Transfer; Models, Molecular; Mutagenesis, Site-Directed; Nanocomposites; Nanostructures; Nanotechnology; Nonlinear Dynamics; Optical Phenomena; Quantum Dots; Tellurium

In this study, thioglycolic acid capped-CdTe quantum dots (QDs) were modified by polyethylenimine (PEI), and then combined with fluorescein isothiocyanate (FITC) to fabricate FITC-CdTe conjugates. The self-assembly of FITC, CdTe and PEI was ascribed to electrostatic interactions in aqueous solution. The resulting conjugates were developed toward two routes. In route one, ratiometric photoluminescence (PL) intensity of conjugates (IFITC/IQDs) was almost linear toward pH from 5.3 to 8.7, and a ratiometric PL sensor of pH was favorable obtained. In route two, firstly added S(2-) induced remarkable quenching of QDs PL peak (at the "OFF" state), which was restored due to following addition of Cd(2+) (at the "ON" state). In the conjugates, successive introduction of S(2-) and Cd(2+) hardly influenced on FITC PL peaks. According to this PL "OFF-ON" mode, a ratiometric PL method for the detection of Cd(2+) was achieved. Experimental results confirmed that the IFITC/IQDs exhibited near linear proportion toward Cd(2+) concentration in the range from 0.1 to 15μM, and the limit of detection was 12nM. Interferential experiments adequately testified that the proposed sensors of pH and Cd(2+) were practicable in real samples and complex systems. In comparison with conventional analytical techniques, the ratiometric PL method was simple, rapid, economic and highly selective.

Topics: Cadmium; Cadmium Compounds; Fluorescein-5-isothiocyanate; Fluorescence; Hydrogen-Ion Concentration; Polyethyleneimine; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thioglycolates

We report herein the controllable generation of encodable multi-fluorescence CdTe@carbon nanoparticles (CdTe@C NPs) via the pyrolysis of quantum dot/photonic crystal (QD/PC) guest-host ensembles. The precursors of CdTe/poly(styrene-co-glycidylmethacrylate) (PS-co-PGMA) QD/PC guest-host ensembles were initially formed via the assembly of epoxy groups of PCs and carboxyl groups on the surface of CdTe QDs, followed by a pyrolysis process to generate CdTe@C NPs. The as-prepared CdTe@C NPs not only integrate the optical properties for both the carbon and CdTe QD constituents, but also enable an impressive enhancement of the fluorescence lifetime for CdTe QDs. The multifarious fluorescent spectra coding for CdTe@C NPs was further generated through regulating the embedded sizes or concentrations of CdTe QDs and the excitation wavelength, and their applications in DNA detection and luminescent patterns were achieved.

Topics: Cadmium Compounds; Carbon; Crystallization; Fluorescent Dyes; Luminescent Measurements; Macromolecular Substances; Materials Testing; Molecular Conformation; Nanoparticles; Particle Size; Quantum Dots; Surface Properties; Tellurium

Defects in Au-catalysed CdTe nanowires vapour-liquid-solid-grown on polycrystalline underlayers have been critically evaluated. Their low-temperature photoluminescence spectra were dominated by excitonic emission with rarely observed above-gap emission also being recorded. While acceptor bound exciton lines due to monovalent metallic impurities (Ag, Cu or Na) were seen, only deeper, donor-acceptor-pair emission could be attributed to the Au contamination that is expected from the catalyst. Annealing under nitrogen acted to enhance the single crystal-like PL emission, whilst oxidizing and reducing anneals of the type that is used in solar cell device processing caused it to degrade. The incidence of stacking faults, polytypes and twins was related only to the growth axes of the wires (<111> 50%, <112> 30% and <110> 20%), and was not influenced by annealing. The potential electrical activity of the point and extended defects, and the suitability of these nanowire materials (including processing steps) for solar cell applications, is discussed. Overall they have a quality that is superior to that of thin polycrystalline films, although questions remain about recombination due to Au.

Topics: Cadmium Compounds; Electric Power Supplies; Equipment Design; Equipment Failure Analysis; Nanotechnology; Nanotubes; Particle Size; Solar Energy; Tellurium

The mechanisms of toxicity related to human hepatocellular carcinoma HepG2 cell exposures to cadmium telluride quantum dots (CdTe-QDs) were investigated. CdTe-QDs caused cytotoxicity in HepG2 cells in a dose- and time-dependent manner. Treated cells showed an increase in reactive oxygen species (ROS). Altered antioxidant levels were demonstrated by depletion of reduced glutathione (GSH), a decreased ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) and an increased NF-E2-related Factor 2 (Nrf2) activation. Enzyme assays showed that superoxide dismutase (SOD) activity was elevated whereas catalase (CAT) and glutathione-S-transferase (GST) activities were depressed. Further analyses revealed that CdTe-QD exposure resulted in apoptosis, indicated by changes in levels of caspase-3 activity, poly ADP-ribose polymerase (PARP) cleavage and phosphatidylserine externalization. Extrinsic apoptotic pathway markers such as Fas levels and caspase-8 activity increased as a result of CdTe-QD exposure. Involvement of the intrinsic/mitochondrial apoptotic pathway was indicated by decreased levels of B-cell lymphoma 2 (Bcl2) protein and mitochondrial cytochrome c, and by increased levels of mitochondrial Bcl-2-associated X protein (Bax) and cytosolic cytochrome c. Further, mitogen-activated protein kinases (MAPKs) such as c-Jun N-terminal kinases (JNK), extracellular signal-regulated kinases (Erk1/2), and p38 were all activated. Our findings reveal that CdTe-QDs cause oxidative stress, interfere with antioxidant defenses and activate protein kinases, leading to apoptosis via both extrinsic and intrinsic pathways. Since the effects of CdTe-QDs on selected biomarkers were similar or greater compared to those of CdCl2 at equivalent concentrations of cadmium, the study suggests that the toxicity of CdTe-QDs arises from a combination of the effects of cadmium and ROS generated from the NPs.

Topics: Apoptosis; Cadmium Compounds; Carcinoma, Hepatocellular; Catalase; Cell Survival; Cytochromes c; Glutathione; Glutathione Disulfide; Hep G2 Cells; Humans; Liver Neoplasms; Microscopy, Confocal; Mitogen-Activated Protein Kinases; NF-E2-Related Factor 2; Oxidative Stress; Quantum Dots; Signal Transduction; Superoxide Dismutase; Tellurium

Understanding the biophysical and chemical interactions of nanoprobes and their fate upon entering live cells is critical for developing fundamental insights related to intracellular diagnostics, drug delivery and targeting. In this article we report herein a single molecule analysis procedure to quantitate site-specific exclusive membrane binding of N-acetyl-L-cysteine (NAC)-capped cadmium telluride (CdTe) quantum dots (QDs) in A-427 lung carcinoma cells (k(eq) = 0.075 ± 0.011 nM(-1)), its relative intracellular distribution and dynamics using fluorescence correlation spectroscopy (FCS) combined with scanning confocal fluorescence lifetime imaging (FLIM). In particular, we demonstrate that the binding efficacy of QDs to the cell membrane is directly related to their size and the targeting of QDs to specific membrane sites is exclusive. We also show that QDs are efficiently internalized by endocytosis and enclosed within the endosome and organelle-dependent diffusion dynamics can be monitored in live cells.

Topics: Binding Sites; Cadmium Compounds; Cell Membrane; Fluorescence; Humans; Microscopy, Confocal; Organelles; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium; Thermodynamics; Tumor Cells, Cultured; Water

A facile and ultrasensitive electrochemiluminescent (ECL) immunosensor for detection of prostate-specific antigen (PSA) was designed by using CdTe quantum dots coated silica nanoparticles (SiO2@QDs) as bionanolabels. To construct such an electrochemiluminescence immunosensor, gold nanoparticles-dotted graphene composites were immobilized on the working electrode, which can increase the surface area to capture a large amount of primary antibodies as well as improve the electronic transmission rate. The as-prepared SiO2@QDs used as bionanolabels, showed good ECL performance and good ability of immobilization for secondary antibodies. The approach provided a good linear response ranging from 0.005 to 10 ng mL(-1) with a low detection limit of 0.0032 ng mL(-1). Such immunosensor showed good precision, acceptable stability, and reproducibility. Satisfactory results were obtained for determination of PSA in human serum samples. Therefore, the proposed method provides a new promising platform of clinical immunoassay for other biomolecules.

Topics: Amplifiers, Electronic; Biosensing Techniques; Cadmium Compounds; Coated Materials, Biocompatible; Conductometry; Electrodes; Equipment Design; Equipment Failure Analysis; Gold; Graphite; Immunoassay; Luminescent Measurements; Metal Nanoparticles; Quantum Dots; Reproducibility of Results; Sensitivity and Specificity; Tellurium

Extremely efficient quenching of the excited state of aqueous CdTe quantum dots (QDs) by photoinduced electron transfer to a europium cyclen complex is facilitated by surface coordination to the thioglycolic acid capping ligand. The quenching dynamics are elucidated using steady-state emission and picosecond transient absorption.

Topics: Cadmium Compounds; Coordination Complexes; Cyclams; Electrons; Europium; Heterocyclic Compounds; Luminescence; Quantum Dots; Surface Properties; Tellurium; Thioglycolates

Although the unique optical properties of surface-modified quantum dots (QDs) have attracted wide interest in molecular biology and bioengineering, there are very few reports of their in vivo biodistribution, due to a lack of analytical techniques for characterizing the dynamic variation of QDs in living animals. In this study, we used an in vivo online monitoring system and a batch-wise elemental analytical method to investigate the biodistribution/extravasation of various surface-modified CdTeSe/ZnS (QDs) in rat liver. It is found that the surface modification dictated not only the blood retention profile but also the degree of extravasation and the clearance of extracellular QDs, making it an important variable for regulating the transfer and exchange process of QDs among three physiological compartments-bloodstream, extracellular space and Kupffer cells/hepatocytes.

Topics: Animals; Cadmium Compounds; Equipment Design; Kinetics; Liver; Mass Spectrometry; Perfusion; Polyethylene Glycols; Quantum Dots; Rats; Selenium; Solid Phase Extraction; Sulfides; Tellurium; Tissue Distribution; Zinc Compounds

With the widespread use of quantum dots (QDs), the likelihood of exposure to quantum dots has increased substantially. The application of quantum dots in numerous biomedical areas requires detailed studies on their toxicity. In this study, we aimed to determine the threshold dose which reduced or eliminated CdTe-induced toxicity in L929 cells by controlling the exposure dose. We established a cellular model of acute exposure to CdTe QDs. Cells were exposed to different concentrations of CdTe QDs (2.2 nm and 3.5 nm) followed by illustrative cytotoxicity analysis. The results showed that low concentrations of CdTe QDs (under 10 µg/mL) promoted cell viability, caused no obvious effect on the rate of cell apoptosis, intracellular calcium levels and changes in mitochondrial membrane potential, while high concentrations significantly inhibited cell viability. In addition, reactive oxygen species in the 10 µg/mL-treated group was significantly reduced compared with the control group. In summary, the cytotoxicity of CdTe QDs on L929 cell is dose-dependent, time-dependent and size-dependent. Low concentrations of CdTe QDs (below 10 µg/mL) may be nontoxic and safe in L929 cells, whereas high concentrations (above 10 µg/mL) may be toxic resulting in inhibition of proliferation and induction of apoptosis in L929 cells.

Topics: Animals; Apoptosis; Cadmium Compounds; Calcium; Cell Line; Cytotoxins; Dose-Response Relationship, Drug; Intracellular Space; Membrane Potential, Mitochondrial; Mice; Quantum Dots; Reactive Oxygen Species; Reference Values; Safety; Tellurium

The resurgence of infectious diseases and associated issues related to antibiotic resistance has raised enormous challenges which may possibly be confronted primarily by nanotechnology routes. One key need of critical significance in this context is the development of an agent capable of inhibiting quorum sensing mediated biofilm formation in pathogenic organisms. In this work we examine the possible use of a nanocomposite, CdTe-TiO2, as an impeder of growth and biofilm. In the presence of CdTe-TiO2, scanning electron microscopy (SEM) analysis shows exposed cells without the surrounding matrix. Confocal laser scanning microscopy shows spatially distributed fluorescence, a typical indication of an impeded biofilm, as opposed to the control which shows matrix-covered cells and continuous fluorescence, typical of biofilm formation. Quantitatively, the inhibition of biofilm was ∼57%. CdTe-TiO2 also exhibits good antibacterial properties against Gram positive and Gram negative organisms by virtue of the generation of reactive oxygen species inside the cells, reflected by a ruptured appearance in the SEM analysis.

Topics: Anti-Bacterial Agents; Bacillus subtilis; Bacterial Infections; Biofilms; Cadmium Compounds; Escherichia coli; Humans; Nanocomposites; Pseudomonas aeruginosa; Quantum Dots; Quorum Sensing; Tellurium; Titanium

The field of light-emitting nanoparticles has experienced an enormous development over the past two decades. The fluorescence of these nanometer-size crystalline particles, called quantum dots (QDs), can be both quenched and enhanced by different compounds. Since a high percentage of articles related to QDs are focused on theoretical studies, the development of analytical methods with real applications is an important step in order to progressively demonstrate the versatility of these particles. Moreover, taking into account that most of the QDs-based analytical methods are non-automated, the development of automated flow methodologies is still a field that presents an important analytical potential. With this purpose, two automatic methodologies, multicommutated flow injection analysis and sequential injection analysis, have been here applied to the analysis of quinolones in pharmaceutical formulations, making use of the quenching effect caused by the analytes over mercaptopropionic acid-capped CdTe QDs fluorescence. Both methodologies were compared in terms of versatility, sample throughput, sensitivity, etc., and applied to the determination of five quinolones in pharmaceutical preparations available in the Spanish Pharmacopoeia. The detection limits ranged between 26 and 50μmolL(-1), and Relative Standard Deviations lower than 3% were observed in all cases.

Topics: 3-Mercaptopropionic Acid; Automation; Cadmium Compounds; Flow Injection Analysis; Fluorescence; Limit of Detection; Quantum Dots; Quinolones; Sensitivity and Specificity; Tellurium

To investigate oxidative damage effects induced by CdTe quantum dots (QDs) in mice liver.. 40 ICR mice were randomly divided into 5 groups, one control group (normal saline), four CdTe QDs (exposed by intravenous injection of 0.2 ml CdTe QDs at the concentration of 0, 0.5, 5, 50 and 500 nmol/ml respectively). All mice were decapitated 24h after the injection. Concentration of MDA and the activities of SOD, CAT, 8-OHdG expression were examined by immunohistochemistry and hepatocellular apoptosis was measured with TUNEL resperctively.. The results showed in 500 nmol/ml CdTe QDs group, MDA concentration in the liver tissue were significantly higher than those of control group (P < 0.05). The activities of SOD in 50 and 500 nmol/ml and CAT in 5, 50 and 500 nmol/ml CdTe QDs groups were significantly lower than those of control group (P < 0.01). Positive staining for 8-OHdG appeared in 50 and 500 nmol/ml CdTe QDs groups and the apoptosis of liver cells was observed in 500 nmol/ml CdTe QDs group by TUNEL technique.. It was suggested that CdTe QDs at certain doses could induce oxidative damage effects of the mice liver in the condition of this experiment.

Topics: Animals; Apoptosis; Cadmium Compounds; DNA Damage; Liver; Male; Mice; Mice, Inbred ICR; Oxidative Stress; Quantum Dots; Tellurium

A facile and sensitive label-free approach for detection of thrombin based on CdTe quantum dots (QDs) and thrombin binding aptamer (TBA) is presented. The crude QDs can be "activated" with fluorescence enhancement by adding extra Cd(2+) to the solution in basic medium. As a result, the positively charged Cd(2+)-activating CdTe QDs could interact with the negatively charged TBA, leading to fluorescence quenching. When thrombin was added, TBA was induced to form a G-quadruplex structure and combined specifically with its target, releasing the QDs with a recovery of the fluorescence intensity. The sensing approach is based on the strongly specific interactions between TBA and thrombin over the electrostatic interactions between TBA and positively charged QDs. Based on the fluorescence enhancement of QDs, selective detection of thrombin was successfully achieved. A linear response for thrombin was observed in the range from 1.4 nM to 21 nM with a detection limit of 0.70 nM.

Topics: Aptamers, Nucleotide; Cadmium; Cadmium Compounds; Fluorescent Dyes; G-Quadruplexes; Humans; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thrombin

This study explored a simple and fast method utilizing ultraviolet (UV) irradiation to synthesize CdTe/CdS/ZnS QDs in aqueous solution. Based on the reaction of photolysis and chemical deposition, the CdS and ZnS shell can be successively deposited around the thiol-capped CdTe cores through the interaction of Cd²⁺/Zn²⁺ and S²⁻ produced by UV irradiation. The effect of the UV irradiation time, the ratios of thioglycolic acid (TGA)/Cd and TGA/Zn on the shell formation, shell stability, and the photoluminescence (PL) intensity of the QDs, was systematically investigated. Keeping the ratio of TGA/Cd, increasing UV irradiation time from 30 to 120 s, the blue-shift of the fluorescence emission peak position of CdTe/CdS QDs was observed. As the irradiation time increased continuously from 120 to 300 s, the red-shift of the emission peak position was observed. In the total irradiation time, the PL intensity of all the samples was enhanced. By applying 300 s irradiation on the samples, the emission peak was blue-shifted at a fixed TGA/Cd ratio of 1:1 and red-shifted at the ratios of 2:1, 4:1, 8:1, and 13:1. The PL intensity reached its highest value at the ratio of 2:1. The effect of TGA/Zn ratio on ZnS shell formation showed a similar progress. Under an optimum synthesized reaction condition, the particle sizes of CdTe core, CdTe/CdS core-shell and CdTe/CdS/ZnS core-shell-shell QDs were 2.6 nm, 3.4 nm, and 4.6 nm respectively. This study confirmed that with the core-shell-shell structure, CdTe/CdS/ZnS QDs had high anti-oxidability, photostability, and low toxicity. Therefore they can be further used in cell imaging efficiently.

Topics: Biocompatible Materials; Cadmium Compounds; Cell Line; Cell Survival; Fluorescent Dyes; Humans; Microscopy, Confocal; Quantum Dots; Spectrometry, Fluorescence; Sulfides; Tellurium; Ultraviolet Rays; Water; Zinc Compounds

Detection of DNA damage is significant for the evaluation of genotoxicity of new chemicals in the early stages of its development. An electrogenerated chemiluminescence (ECL) biosensor was fabricated to detect specific sequences of DNA by using CdTe@SiO2 as nanoprobes for signal amplification. This DNA biosensor was constructed by self-assembly of an aminated capture DNA on the glass carbon electrode. DNA detection was realized by outputting a remarkable ECL signal of the CdTe@SiO2 labeled probe DNA. When the target DNA was introduced into the system, it was complementary to the probe DNA at the one-half-segment and complementary to the capture DNA at the other half-segment, resulting in the formation of a stable duplex complex. As a result, the CdTe@SiO2 labeled probe was proximate to the electrode surface and the ECL was observed. This DNA biosensor was proved to have a low detection limit (0.03 nM) and a wide dynamic range (from 0.1 nM to 2 μM). Most importantly, the sensing system could differentiate the single base mismatched DNA from the complementary DNA. It was successfully applied to study the damage to DNA caused by several genotoxicity chemicals, which was rapid, simple, reliable and sensitive compared to the classical biological methods.

Topics: Base Sequence; Cadmium Compounds; Carbon; DNA; DNA Damage; Electrochemistry; Electrodes; Glass; Luminescent Measurements; Nanoparticles; Nanotechnology; Silicon Dioxide; Tellurium

In recent years, the number of scientific papers regarding the use of quantum dots (QDs) has increased almost exponentially, especially emphasizing their use for new applications and describing new approaches. One of the future trends in the development of new methods of analysis is the use of automated methodologies. Among them, Multicommutated Flow Injection Analysis has been here selected in order to show its potentiality in pharmaceutical and food analysis. Using water-soluble CdTe QDs modified by mercaptopropionic acid, a flow system was developed for the determination of ascorbic acid. The system was based on the quenching effect produced by ascorbic acid on the fluorescence of QDs. Under the optimized conditions, the relationship between the fluorescence intensity of the QDs and ascorbic acid concentration was linear in the range of 12-250 μg mL(-1), obtaining a sample throughput of 68 determinations per hour. The proposed method was applied to the determination of ascorbic acid in pharmaceutical formulations, goji capsules and fruit juices. The results obtained were in good agreement with those showed by a reference method, so indicating the utility of the proposed method in the clinical and alimentary fields.

Topics: 3-Mercaptopropionic Acid; Ascorbic Acid; Beverages; Cadmium Compounds; Capsules; Chemistry, Pharmaceutical; Equipment Design; Flow Injection Analysis; Food Analysis; Quantum Dots; Spectrometry, Fluorescence; Tellurium

An ultrasensitive electrochemiluminescent immunoassay (ECLIA) for aflatoxins M1 (ATM1) in milk using magnetic Fe3O4-graphene oxides (Fe-GO) as the absorbent and antibody-labeled cadmium telluride quantum dots (CdTe QDs) as the signal tag is presented. Firstly, Fe3O4 nanoparticles were immobilized on GO to fabricate the magnetic nanocomposites, which were used as absorbent to ATM1. Secondly, aflatoxin M1 antibody (primary antibody, ATM1 Ab1), was attached to the surface of the CdTe QDs-carbon nanotubes nanocomposite to form the signal tag (ATM1 Ab1/CdTe-CNT). The above materials were characterized. The optimal experimental conditions were obtained. Thirdly, Fe-GO was employed for extraction of ATM1 in milk. Results indicated that it can adsorb ATM1 efficiently and selectively within a large extent of pH from 3.0 to 8.0. Adsorption processes reached 95% of the equilibrium within 10 min. Lastly, the ATM1 with a serial of concentrations absorbed on Fe-GO was conjugated with ATM1 Ab1/CdTe-CNT signal tag based on sandwich immunoassay. The immunocomplex can emit a strong ECL signal whose intensity depended linearly on the logarithm of ATM1 concentration from 1.0 to 1.0 × 10(5) pg/mL, with the detection limit (LOD) of 0.3 pg/mL (S/N = 3). The method was more sensitive for ATM1 detection compared to the ELISA method. Finally, ten samples of milk were tested based on the immunoassay. The method is fast and requires very little sample preparation, which was suitable for high-throughput screening of mycotoxins in food.

Topics: Aflatoxin M1; Animals; Antibodies; Cadmium Compounds; Electrochemistry; Food Contamination; Graphite; Immunoassay; Luminescent Measurements; Magnetite Nanoparticles; Microscopy, Electron, Transmission; Milk; Nanocomposites; Nanotubes, Carbon; Quantum Dots; Tellurium; X-Ray Diffraction

The cytotoxicity of quantum dots (QDs) under normal conditions has received more and more attention, but their cytotoxicity under light illumination has not been fully investigated. In this study, different sized CdTe QDs coated with mercaptopropionic acid (MPA) and N-acetylcysteine (NAC) were employed to investigate the influences of size distribution and surface modification on their UV-enhanced cytotoxicity and mechanism. The results indicated that different sized MPA-CdTe QDs exhibited distinct cytotoxicity under UV illumination and the smaller-sized QDs presented more obviously damages to cells than the larger-sized QDs. Comparing with MPA-CdTe QDs, NAC-CdTe QDs had better cellular metabolizability and lower cytotoxicity. The generation of reactive oxygen species (ROS) were also investigated. The results revealed that ROS in cells containing MPA-CdTe QD538 were about 1.7 times of NAC-CdTe QD538 under UV illumination. ROS might play an important role in the UV-enhanced cytotoxicity of QDs. By selecting appropriate surface modifications and particle sizes, the cytotoxicity of QDs under UV illumination could be controlled.

Topics: Cadmium Compounds; Cell Line, Tumor; Cell Survival; Humans; Quantum Dots; Tellurium; Ultraviolet Rays

Aimed at the facile detection of lengthy DNA molecules, an easily operated sandwich-type electrochemiluminescence (ECL) DNA biosensor was constructed on a glassy carbon electrode (GCE) based on CdTe quantum dots coated hollow ZnO nanoparticles (CdTe-ZnO NPs)-S(2)O(8)(2-) ECL system in this work. To fabricate a high-performance protocol, the GCE surface was successively modified by graphene nanosheet (GS), carbon nanotube (CNT) and gold nanoparticles (AuNPs) to form AuNPs dotted CNT-GS composites (Au@CNT-GS) platform, which improved the electronic transmission rate as well as increased the amount of immobilized capture probe CMV-F (S(1)). For further ultrasensitive, stable and low-potential ECL detection, CdTe-ZnO NPs were synthesized, and employed to label signal probe T7 promoter (S(3)). Based on the hybridization effect, the immobilized capture probe S(1), target DNA and labeled signal probe S(3) formed a sandwich-type DNA complex, which produced the ECL emission in the presence with S(2)O(8)(2-) coreactant. Under optimal conditions, the DNA ECL biosensor showed a good linear range over 10(-14) M to 10(-19) M with a low detection limit of 0.61 × 10(-19) M. The proposed strategy demonstrates a reproducible, stable, and potent method that can be expanded to detect the genome which exists in living cells.

Topics: Base Sequence; Biosensing Techniques; Cadmium Compounds; DNA; Electrochemistry; Electrodes; Gold; Graphite; Luminescent Measurements; Nanotubes, Carbon; Reproducibility of Results; Tellurium; Zinc Oxide

Well-defined Au-SiO(2)-CdTe composite nanoparticles were synthesized via a multistep chemical approach in water solution to gain insight into the interaction between metal and semiconductor nanostructures. Photoluminescence measurement reveals that the fluorescence of CdTe quantum dots (QDs) in this composite with optimized SiO(2) thickness (4 nm) has over ten times enhancement compared with that of bare CdTe QDs. The considerable fluorescence enhancement of CdTe QDs is attributed to the surface plasmon resonance, which is further confirmed by the lifetime measurement. The enhanced fluorescence can be used to improve the performance of CdTe QDs as fluorescence probe and may find potential applications in biolabeling.

Topics: Cadmium Compounds; Fluorescent Dyes; Gold; Nanoparticles; Photons; Silicon Dioxide; Surface Plasmon Resonance; Tellurium

The discrimination of ferrous and ferric states in the human body is one of the basic issues for disease control and prevention because Fe(II) and Fe(III) are a crucial redox pair during the process of material and energy metabolism. Herein, aqueous CdTe quantum dots (QDs) with diversified surface functionalities are applied to discriminate between heme (Fe(II)) and hemin (Fe(III)) by virtue of their difference in quenching QD fluorescence. In aqueous media, the interaction between QDs and heme/hemin mainly involves electrostatic interaction, which is greatly determined by the surface functionalities of the QDs. Thus, by combining the different fluorescence quenching behavior of carboxyl- and/or hydroxyl-functionalized QDs, heme and hemin are discriminated between. In comparison to the discrimination using QDs with single surface functionality, the current method has improved reliability and accuracy.

Topics: Cadmium Compounds; Feasibility Studies; Heme; Hemin; Oxidation-Reduction; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium; Water

High quality and facile DNA functionalized quantum dots (QDs) as efficient fluorescence nanomaterials are of great significance for bioimaging both in vitro and in vivo applications. Herein, we offer a strategy to synthesize DNA-functionalized Zn(2+) doped CdTe QDs (DNA-QDs) through a facile one-pot hydrothermal route. DNA is directly attached to the surface of QDs. The as-prepared QDs exhibit small size (3.85 ± 0.53 nm), high quantum yield (up to 80.5%), and excellent photostability. In addition, the toxicity of QDs has dropped considerably because of the Zn-doping and the existence of DNA. Furthermore, DNA has been designed as an aptamer specific for mucin 1 overexpressed in many cancer cells including lung adenocarcinoma. The aptamer-functionalized Zn(2+) doped CdTe QDs (aptamer-QDs) have been successfully applied in active tumor-targeted imaging in vitro and in vivo. A universal design of DNA for synthesis of Zn(2+) doped CdTe QDs could be extended to other target sequences. Owing to the abilities of specific recognition and the simple synthesis route, the applications of QDs will potentially be extended to biosensing and bioimaging.

Topics: Animals; Aptamers, Nucleotide; Cadmium Compounds; Cell Line, Tumor; Chlorocebus aethiops; Humans; Mice, Nude; Neoplasms; Optical Imaging; Quantum Dots; SELEX Aptamer Technique; Tellurium; Vero Cells; X-Ray Diffraction; Zinc

Results of the studies related to fabrication of sensitive electrochemical biosensor using an interface based on quantum dots (QDs) self-assembly is reported. The QDs assembly is sought to provide improved fundamental characteristics to the electrode interface in terms of electroactive surface area, diffusion coefficient, and electron transfer kinetics. This QDs modified electrode has been utilized to serve as a transducer surface for covalent immobilization of chronic myelogenous leukemia (CML) specific probe oligonucleotide, designed from the BCR-ABL fusion gene. The electrochemical characteristics of this biosensor toward various designed synthetic oligonucleotides reveal a significant enhancement in its mismatch discrimination capability compared to the biosensing assay without QDs under similar experimental conditions. The sensing characteristics of this biosensor offer a potential for detection of target oligonucleotide at a concentration as low as 1.0 pM. Furthermore, the PCR-amplified CML-positive patient samples with various BCR-ABL transcript ratios can be electrochemically distinguished from healthy samples, indicating promising application of the QDs based biosensor for clinical investigations.

Topics: Biosensing Techniques; Cadmium Compounds; Electrodes; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Oligonucleotide Probes; Particle Size; Quantum Dots; Surface Properties; Tellurium

The increasing use of products derived from nanotechnology has raised concern about their potential toxicity to aquatic life. This study sought to examine the comparative immunotoxicity of capped cadmium sulphide/cadmium telluride (CdS/CdTe) quantum dots (QDs) and possible impact of particle/aggregate size on two bivalves (Mytilus edulis and Elliptio complanata) and a fish (Oncorhynchus mykiss). The QDs were dispersed in sterile water and fractionated using a series of micro/ultrafiltration membranes of decreasing pore size: 450 nm, 100 nm, 50 nm, 25 nm, 100 kDa (6.8 nm), 30 kDa (4.6 nm), 10 kDa (3.2 nm) and 1 kDa (1.5 nm). The total concentrations of cadmium and tellurium were determined for the filtered material and for that retained on the filters (retentate). The immunotoxicity was determined by measuring cell viability and phagocytosis. Results revealed that nanoparticles retained on the ultrafilters had a higher Cd/Te ratio compared to the permeate fraction (ratio of 5 and 2 respectively) which could indicate that the CdS core was not associated with the permeable fraction of Cd. Our results demonstrate that the toxicity of CdS/CdTe QDs was concentration and size dependent. Large CdS/CdTe QD aggregates (25 nm < size < 100 nm) reduced phagocytosis more than did smaller nanoparticles (<25 nm). Moreover, our results revealed that the different species responded differently to these fractions. Mytilus edulis hemocytes were less sensitive to CdS/CdTe QDs than the Oncorhynchus mykiss macrophage and Elliptio complanata hemocytes.

Topics: Animals; Bivalvia; Cadmium Compounds; Cell Survival; Hemocytes; Macrophages; Oncorhynchus mykiss; Particle Size; Phagocytosis; Quantum Dots; Sulfides; Tellurium

In this paper, the efficient quenching effect of deoxyguanosine-5'-phosphate (dGMP) on anodic electrochemiluminescence (ECL) of the CdTe/ZnS quantum dots (QDs) is reported for the first time. This ECL quenching was found to be specific for free dGMP and not observed for dGMP residues in different DNA structures. The unique dGMP-based QDs ECL quenching was then utilized to develop a versatile biosensing strategy to determine various protein-DNA interactions with the assistance of exonuclease, Exo I, to hydrolyze DNA and liberate dGMP. Taking single-stranded DNA binding protein (SSB) and thrombin as examples, two novel detection modes have been developed based on dGMP-QDs ECL strategy. The first method used hairpin probes and SSB-promoted probe cleavage by Exo I for facile signal-off detection of SSB, with a wide linear range of 1-200 nM and a low detection limit of 0.1 nM. The second method exploited aptamer-thrombin binding to protect probes against Exo I degradation for sensitive signal-on detection of thrombin, giving a linear response over a range of 1-150 nM and a detection limit as low as 0.1 nM. Both methods were homogeneous and label-free without QDs or DNA modification. Therefore, this dGMP-specific QDs ECL quenching presents a promising detection mechanism suitable for probing various protein-nucleic acid interactions.

Topics: Biosensing Techniques; Cadmium Compounds; Deoxyguanine Nucleotides; Electrochemical Techniques; Luminescent Measurements; Nucleic Acids; Protein Binding; Quantum Dots; Tellurium; Thrombin; Zinc Sulfate

Hormones regulate the mechanism of plant growth and development, senescence, and plants' adaptation to the environment; studies of the molecular mechanisms of plant hormone action are necessary for the understanding of these complex phenomena. However, there is no measurable signal for the hormone signal transduction process. We synthesized and applied a quantum dot-based fluorescent probe for the labeling of jasmonic acid (JA) binding sites in plants. This labeling probe was obtained by coupling mercaptoethylamine-modified CdTe quantum dots with JA using N-hydroxysuccinimide (NHS) as a coupling agent. The probe, CdTe-JA, was characterized by transmission electron microscopy, dynamic light scattering, and fluorescent spectrum and applied in labeling JA binding sites in tissue sections of mung bean seedlings and Arabidopsis thaliana root tips. Laser scanning confocal microscopy (LSCM) revealed that the probe selectively labeled JA receptor. The competition assays demonstrated that the CdTe-JA probe retained the original bioactivity of JA. An LSCM three-dimensional reconstruction experiment demonstrated excellent photostability of the probe.

Topics: Arabidopsis; Binding Sites; Cadmium Compounds; Cyclopentanes; Cysteamine; Imaging, Three-Dimensional; Molecular Imaging; Oxylipins; Quantum Dots; Seedlings; Spectrometry, Fluorescence; Tellurium

The catalytic activity of copper ion gives, from the physiological point of view, a central role in many biological processes. Variations in the composition and location of cellular copper have been addressed given their physiological and pathological consequences. In this paper L-cysteine capped CdTe quantum dots is used for the fluorimetric determination of Cu(II) in biological samples from healthy individuals and patients admitted to the Intensive Care Units (ICU). An acceptable homogeneity in the CdTe QDs size has been obtained with an average value of 3 nm. No significant alterations in the spectral properties were observed for 2 months when stored in vacutainers at 6°C and a concentration of approximately 2 μM. Data from oxidative stress markers such superoxide dismutase, total antioxidant capacity and DNA damage can be correlated with a Cu(II) deficiency for the ICU patients as measured by flame-atomic absorption spectroscopy (FAAS) and inductively coupled plasma source mass spectrometry (ICP-MS). Aqueous solutions 0.3 μM of L-cysteine capped CdTe QDs in MOPS buffer (6 mM, pH 7.4) used at 21°C in the range 15-60 min after preparation of the sample for the measurements of fluorescence gives contents in Cu(II) for erythrocytes in good agreement with those obtained in FAAS and ICP-MS but the comparative ease of use makes the fluorimetric technique more suitable than the other two techniques for routine analysis.

Topics: Cadmium Compounds; Comet Assay; Copper; Critical Illness; Cysteine; DNA Damage; Erythrocytes; Fluorometry; Humans; Intensive Care Units; Ions; Mass Spectrometry; Oxidative Stress; Quantum Dots; Spectrophotometry, Atomic; Superoxide Dismutase; Tellurium

Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24h of CdSO4 or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks. Measured levels of stress defense and DNA repair genes were elevated in both cases. However, removal of bulky DNA adducts by nucleotide excision repair (NER) was inhibited with CdSO4 but not with CdTe QDs. The adverse effects caused by acute exposure of CdTe QDs might be mediated through differing mechanisms than those resulting from ionic cadmium toxicity, and studying the effects of metallic components may be not enough to explain QD toxicities in aquatic organisms.

Topics: Animals; Cadmium Compounds; Cell Culture Techniques; Cell Survival; Cells, Cultured; DNA Repair; Hepatocytes; Liver; Quantum Dots; Reactive Oxygen Species; Sulfates; Tellurium; Water Pollutants, Chemical; Zebrafish

The purpose of this paper was to investigate the effect of photon flux on the recorded energy spectrum and images produced with a photon-counting detector. We used a photon-counting cadmium telluride (CdTe) x-ray detector (model PID350, Oy Ajat, Finland). The CdTe array was composed of 16 384 pixels, each 0.35 × 0.35 × 0.75 mm(3) in dimension. The photon flux is controlled by an additional aluminum filter (1, 10, 20, 30 and 40 mm). Images were acquired at three different tube voltages (50, 70 and 90 kVp) with various thicknesses of photon flux control (PFC) filters. The data acquisition time was changed to acquire an approximately equal number of counts within the selected energy window between different thicknesses of PFC filters at the same tube voltage. A phantom was manufactured to evaluate the photon flux effect on the image. The phantom was made from polymethyl methacrylate and four concentrations of iodine. The photon flux effect on the image was evaluated by the signal-difference-to-noise ratio (SDNR) between iodine and the background material. The changes of photon flux affected the recorded energy spectra and image. The thickness of the PFC filter that showed the maximum SDNR differed according to the tube voltage. The 10 mm PFC filter showed the highest SDNR at 50 and 70 kVp, while the 30 mm PFC filter exhibited the highest SDNR at 90 kVp. The SDNR was improved up to, on average, 30-fold in optimal photon flux conditions which acquired a spectrum including the lowest electronic noise with no pulse pile-up effect. The results of this study showed that the photon flux affected not only the acquired energy spectrum but also the image. Based on these results, the spectral distortion correction should be considered in connection with the image that is the ultimate purpose of medical imaging.

Topics: Cadmium Compounds; Phantoms, Imaging; Photons; Tellurium; Tomography, X-Ray Computed

We have investigated crosstalk in HgCdTe photovoltaic pixel arrays employing a photon trapping (PT) structure realized with a periodic array of pillars intended to provide broadband operation. We have found that, compared to non-PT pixel arrays with similar geometry, the array employing the PT structure has a slightly higher optical crosstalk. However, when the total crosstalk is evaluated, the presence of the PT region drastically reduces the total crosstalk; making the use of the PT structure not only useful to obtain broadband operation, but also desirable for reducing crosstalk in small pitch detector arrays.

Topics: Artifacts; Cadmium Compounds; Computer Simulation; Computer-Aided Design; Equipment Design; Equipment Failure Analysis; Light; Mercury Compounds; Models, Theoretical; Photometry; Scattering, Radiation; Signal Processing, Computer-Assisted; Signal-To-Noise Ratio; Tellurium

Picoliter droplets were developed as microreactors for ultrafast and continuous synthesis of multi-color, water-soluble CdTe quantum dots (QDs). Through a slight change in the local controllable reaction temperature of 1-2 °C, we could obtain a series of different colored fluorescent QDs in about 1 min.

Topics: Cadmium Compounds; Color; Fluorescent Dyes; Quantum Dots; Solubility; Tellurium; Time Factors; Water

To observed the chromosome oberration of CHL cells induced by CdTe QDs.. The chromosome oberration test of Chinese hamster lung (CHL) cell was conducted in CdTe QDs at the concentrations of 1.6, 3.2, 6.3, 12.6 and 25.2 microl/ml, under the metabolic (+S9) and non-metabolic (-S9) activation systems.. The chromosome oberration rate of 12.6 and 25.2 microl/ml CdTe QDs groups were significantly higher than the control groups (P<0.01) Under the condition of metabolic activation. Main types of chromosomal aberrations was broken, fragmented and exchange.. It was suggested that CdTe QDs could induce the effects of chromosome oberration under the metabolic activation systems (+S9).

Topics: Animals; Cadmium Compounds; Cell Line; Chromosome Aberrations; Cricetinae; Cricetulus; Fibroblasts; Lung; Quantum Dots; Tellurium

Two complementary colors mixed in a proper proportion will produce a neutral color in the color theory. A novel colorimetric method on basis of the color complementarity principle has been well-established to detect recombinant prion protein (rPrP). We found that a colorless solution appeared after mixing orange CdTe quantum dots (QDs) with green-blue malachite green (MG) because of color complementarity. After the addition of rPrP into the mixed solution, the color changed from colorless to green-blue because rPrP could induce the aggregation of QDs, rapidly. And it could be observed by naked eyes. Based on this phenomenon, we developed a simple assay for visual detection of rPrP. At the same time, we obtained excellent correlation between absorption and concentrations of rPrP from 1 nmol L(-1) to 78 nmol L(-1) with the limit of detection of 0.3 nmol L(-1) (3σ). Moreover, it can be applied to determine rPrP in human serum successfully. Importantly, this assay possesses the advantages of simplicity, rapidity, sensitivity, and selectivity, and shows the potential in the clinical diagnostic test of early prion disease and provides the possibility of preventing the spread of prion diseases.

Topics: Biosensing Techniques; Cadmium Compounds; Colorimetry; Humans; Limit of Detection; Prions; Quantum Dots; Recombinant Proteins; Tellurium

In this paper, we report a simple, selective, sensitive and low-cost turn-on photoluminescent sensor for cysteine and homocysteine based on the fluorescence recovery of the CdTe/CdS quantum dots (QDs)-phenanthroline (Phen) system. In the presence of Phen, the fluorescence of QDs could be quenched effectively due to the formation of the non-fluorescent complexes between water-soluble thioglycolic acid (TGA)-capped QDs and Phen. Subsequently, upon addition of cysteine and homocysteine, the strong affinity of cysteine and homocysteine to QDs enables Phen to be dissociated from the surface of QDs and to form stable and luminescent complexes with cysteine and homocysteine in solution. Thus, the fluorescence of CdTe/CdS QDs was recovered gradually. A good linear relationship was obtained from 1.0 to 70.0 μM for cysteine and from 1.0 to 90.0 μM for homocysteine, respectively. The detection limits of cysteine and homocysteine were 0.78 and 0.67 μM, respectively. In addition, the method exhibited a high selectivity for cysteine and homocysteine over the other substances, such as amino acids, thiols, proteins, carbohydrates, etc. More importantly, the sensing system can not only achieve quantitative detection of cysteine and homocysteine but also could be applied in semiquantitative cysteine and homocysteine determination by digital visualization. Therefore, as a proof-of-concept, the proposed method has potential application for the selective detection of cysteine and homocysteine in biological fluids.

Topics: Body Fluids; Cadmium Compounds; Cysteine; Homocysteine; Humans; Phenanthrolines; Quantum Dots; Spectrometry, Fluorescence; Sulfates; Tellurium

An octachlorostyrene (OCS) photoelectrochemical (PEC) immunosensor was developed by cross-linking anti-OCS antibody onto a CdTe/CdS-sensitized TiO2 nanotube arrays (NTAs). The anti-OCS polyclonal antibody was developed in rabbit as a result of immunization with BSA-OCS hapten conjugate. TiO2 NTAs were immobilized firstly with hydrothermally synthesized CdTe quantum dots (QDs), and then CdS which filled the spaces within the CdTe-TiO2 composite and encapsulated the CdTe QDs, forming an ideal stepwise bandedge structure, which benefited the light harvesting. The PEC immunosensor therefore shows high specificity and high sensitivity with a limit of detection of 2.58 pM, and a linear range from 5 pM to 50 nM. The testing time is 4 min. The analysis of river water reveals that the proposed sensor can be applied in the analysis of OCS in real water samples without complicated pre-treatments.

Topics: Animals; Cadmium Compounds; Electrochemical Techniques; Environmental Monitoring; Equipment Design; Immunoassay; Limit of Detection; Nanotubes; Quantum Dots; Rabbits; Rivers; Styrenes; Sulfides; Tellurium; Titanium; Water Pollutants, Chemical

Hydroxytyrosol (HXT) has been reported to have beneficial effects for human health, such as antioxidant and antimicrobial properties and an important contribution to the prevention of cardiovascular disease. Hence, exhaustive research is currently being performed to prepare functional foods, such as tomato juice or milk, with HXT. This paper presents a multi-commutated flow method based on the quenching effect that HXT has on the fluorescence of water-soluble mercaptopropionic acid-capped CdTe quantum dots. Under optimal conditions a linear working range was obtained for concentrations between 10 and 250 ng µl⁻¹. In order to demonstrate the suitability of the proposed method for the determination of HXT, HXT-enriched samples were prepared. Using a QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure for extraction, HXT was determined in the prepared functional foods (milk, infant formula, tomato juice and tomato soup). Recoveries of 100% ± 8%, relative standard deviations (RSDs) lower than 5% and high sample throughput of 70 samples per h show the potential of the system for the analysis of HXT in food samples.

Topics: 3-Mercaptopropionic Acid; Anti-Infective Agents; Antioxidants; Automation, Laboratory; Cadmium Compounds; Chromatography, High Pressure Liquid; Food Inspection; Food, Fortified; High-Throughput Screening Assays; Indicators and Reagents; Limit of Detection; Phenylethyl Alcohol; Quality Control; Quantum Dots; Reproducibility of Results; Spectrometry, Fluorescence; Surface Properties; Tellurium

Synthesis of quantum nanoparticles of specific size, shape and composition are an aspect important in nanotechnology research. Although these nanostructures are routinely synthesized by chemical routes, the use of microorganisms has emerged as a promising option. The synthesis of cadmium telluride (CdTe) quantum dots by two hitherto unreported marine bacteria (Bacillus pumilus and Serratia marcescens) is reported here. Ultraviolet-visible (UV-vis) spectroscopy indicated the synthesis of CdTe nanoparticles and X-ray diffraction (XRD) patterns implicated their crystalline face-centered cubic nature. The size of the synthesized CdTe nanostructures estimated by XRD and dynamic light scattering (DLS) analysis was found to be approximately 10 nm. Photoluminescence (PL) studies were used to confirm the fluorescence properties of these semi-conducting nanoparticles. Scanning electron microscope (SEM) analysis showed the presence of well-defined nanostructures and energy dispersive spectra (EDS) confirmed the microbial synthesis of these nanoparticles. These bio-inspired CdTe nanostructures could be effectively used in imaging of yeast and animal cells. This work thus describes a cost-effective green method for synthesizing highly fluorescent biocompatible CdTe nanoparticles suitable for bio-labeling purposes.

Topics: Bacillus; Cadmium Compounds; Microscopy, Electron, Scanning; Particle Size; Quantum Dots; Serratia marcescens; Spectrophotometry, Ultraviolet; Tellurium; X-Ray Diffraction

A FRET-based nanoprobe consisting of CdTe quantum dot as donor and rhodamine B as acceptor embedded in gelatin nanoparticles was constructed and the photophysics of the system was characterized. The FRET-based sensors were led to at fixed donor/acceptor distance by synthesizing via a two-step desolvation way. This approach allowed for short acceptor-donor separation and thus for high energy transfer efficiencies. The morphology of the nanoprobes was presented spherically and relatively uniform with a diameter of about 100 nm, which was characterized by transmission electron microscope. The luminescent property was proved to be stable in vitro and in living cells, indicating that the nanoprobes can be expected to be promising candidates for biological imaging studies.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Gelatin; Microscopy, Electron, Transmission; Nanoparticles; Quantum Dots; Rhodamines; Spectrometry, Fluorescence; Tellurium

A highly sensitive and selective DNA biosensor based on hybridization chain reaction is described, which combines CdTe quantum dots (QDs) and a ruthenium complex. Based on the variation of fluorescence signals of the CdTe QDs, the target DNA is determined.

Topics: Biosensing Techniques; Cadmium Compounds; Coordination Complexes; DNA; DNA, Viral; Equipment Design; Papillomaviridae; Quantum Dots; Ruthenium; Sensitivity and Specificity; Spectrometry, Fluorescence; Tellurium

We here report the CdTe quantum dot (CdTe QDs)-based sensor for probing vitamin B12 derivatives in aqueous solution. In this paper, simple and sensitive fluorescence quenching measurements has been employed. The Stern-Volmer constant (KSV), quenching rate constant (kq) and binding constant (K) were rationalized from fluorescence quenching measurement. Furthermore, the fluorescence resonance energy transfer (FRET) mechanism was discussed. This method was applicable over the concentration ranging from 1 to 14μg/mL (VB12) with correlation coefficient of 0.993. The limit of detection (LOD) of VB12 was found to be 0.15μg/mL. Moreover, the present approach opens a simple pathway for developing cost-effective, sensitive and selective QD-based fluorescence sensors/probes for biologically significant VB12 in pharmaceutical sample with mean recoveries in the range of 100-102.1%.

Topics: Absorption; Cadmium Compounds; Dosage Forms; Electrochemical Techniques; Energy Transfer; Fluorescent Dyes; Humans; Hydrogen-Ion Concentration; Kinetics; Limit of Detection; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Thiomalates; Vitamin B 12; X-Ray Diffraction

Molecularly imprinted polymers (MIPs) with trinitrophenol (TNP) as a dummy template molecule capped with CdTe quantum dots (QDs) were prepared using 3-aminopropyltriethoxy silane (APTES) as the functional monomer and tetraethoxysilane (TEOS) as the cross linker through a seed-growth method via a sol-gel process (i.e., DMIP@QDs) for the sensing of 2,4,6-trinitrotoluene (TNT) on the basis of electron-transfer-induced fluorescence quenching. With the presence and increase of TNT in sample solutions, a Meisenheimer complex was formed between TNT and the primary amino groups on the surface of the QDs. The energy of the QDs was transferred to the complex, resulting in the quenching of the QDs and thus decreasing the fluorescence intensity, which allowed the TNT to be sensed optically. DMIP@QDs generated a significantly reduced fluorescent intensity within less than 10 min upon binding TNT. The fluorescence-quenching fractions of the sensor presented a satisfactory linearity with TNT concentrations in the range of 0.8-30 μM, and its limit of detection could reach 0.28 μM. The sensor exhibited distinguished selectivity and a high binding affinity to TNT over its possibly competing molecules of 2,4-dinitrophenol (DNP), 4-nitrophenol (4-NP), phenol, and dinitrotoluene (DNT) because there are more nitro groups in TNT and therefore a stronger electron-withdrawing ability and because it has a high similarity in shape and volume to TNP. The sensor was successfully applied to determine the amount of TNT in soil samples, and the average recoveries of TNT at three spiking levels ranged from 90.3 to 97.8% with relative standard deviations below 5.12%. The results provided an effective way to develop sensors for the rapid recognition and determination of hazardous materials from complex matrices.

Topics: Cadmium Compounds; Fluorescent Dyes; Hazardous Substances; Molecular Imprinting; Polymers; Propylamines; Quantum Dots; Silanes; Tellurium; Trinitrotoluene

In this work, we develop a sensitive and selective method for the detection of a cancer biomarker (carcinoembryonic antigen, CEA) based on a new electrochemiluminescence (ECL) energy transfer mechanism, in which the energy transfer occurs from the excited quantum dots (QDs) to the in situ electro-generated quenchers. A CdTe QD-containing composite film is first deposited on the electrode followed by the conjugation of the primary antibody (Ab1) on the film. Subsequent incubation of the modified sensing electrode with CEA and the secondary antibody-alkaline phosphatase-gold nanoparticle labels (Ab2-ALP-AuNP) leads to the formation of the Ab1/CEA/Ab2-ALP-AuNPs immunocomplexes on the electrode surface. The captured ALP catalyzes the p-nitrophenyl phosphate disodium salt (p-NPP) substrate in the ECL detection buffer to p-nitrophenol (p-NP). The potential sweep on the electrode results in the oxidation of p-NP to p-benzoquinone (p-BQ) and the generation of excited QDs. The ECL emission of the excited QDs is therefore quenched through direct energy transfer from the excited QDs to p-BQ. This ECL quenching effect is significantly amplified because of the numerous ALP enzymes involved in each antibody-antigen recognition event. This proposed method of amplified quenching of QD ECL emission offers a low detection limit of 1.67 pg mL(-1) for CEA. In addition, this method exhibits high reproducibility and selectivity and can also be applied to serum samples. Given these advantages, this new ECL energy transfer approach holds great promise for the detection of other biological targets and has potential applications in clinical diagnoses.

Topics: Biosensing Techniques; Cadmium Compounds; Carcinoembryonic Antigen; Humans; Limit of Detection; Luminescent Measurements; Quantum Dots; Tellurium

In this paper, tris(2,3-dibromopropyl) isocyanurate (TBC) is for the first time as far as we know determined by ultrasensitive photoelectrochemical (PEC) immunoassay using an antibody-modified ternary hybrid CdTe/Au-TiO2 nanotube arrays (NTAs) photoelectrode, developed by the pulse electrodeposition technique. The as-prepared hybrid shows enhanced photon absorption and photocurrent response, which subsequently increased the photoelectrical conversion efficiency in the visible region. TBC-antibody (Ab) was developed in rabbits as a result of immunization with the BSA-TBC conjugate and covalently cross-linked onto the CdTe/Au-TiO2 NTAs. Since the photocurrent is highly dependent on the TiO2 surface properties, the specific interaction between TBC and the antibody results in a sensitive change in the photocurrent, which displayed a linear range of 5.0 × 10(-11) to 5.0 × 10(-5) M and a low detection limit of 5.0 × 10(-11) M for TBC determination. This proposed strategy highlights the application of TiO2 nanotube in visible-light-activated photoelectrochemical biosensing, which could largely reduce the destructive effect of UV light on biomolecules.

Topics: Animals; Biosensing Techniques; Cadmium Compounds; Dental Alloys; Electrochemical Techniques; Enzyme-Linked Immunosorbent Assay; Immunoassay; Nanotubes; Organophosphates; Photochemical Processes; Rabbits; Tellurium; Triazines

Quantum dots (QDs) are recognized as some of the most promising candidates for future applications in biomedicine. However, concerns about their safety have delayed their widespread application. Human serum albumin (HSA) is the main protein component of the circulatory system. It is important to explore the interaction of QDs with HSA for the potential in vivo application of QDs. Herein, using spectroscopy and isothermal titration calorimetry (ITC), the effect of glutathione-capped CdTe quantum dots of different sizes on the HSA was investigated. After correction for the inner filter effect, the fluorescence emission spectra and synchronous fluorescence spectra showed that the microenvironment of aromatic acid residues in the protein was slightly changed when the glutathione (GSH)-cadmium telluride (CdTe) QDs was added, and GSH-CdTe QDs with larger particle size exhibited a much higher effect on HSA than the small particles. Although a ground-state complex between HSA and GSH-CdTe QDs was formed, the UV-vis absorption and circular dichroism spectroscopic results did not find appreciable conformational changes of HSA. ITC has been used for the first time to characterize the binding of QDs with HSA. The ITC results revealed that the binding was a thermodynamically spontaneous process mainly driven by hydrophobic interactions, and the binding constant tended to increase as the GSH-CdTe QDs size increased. These findings are helpful in understanding the bioactivities of QDs in vivo and can be used to assist in the design of biocompatible and stable QDs.

Topics: Cadmium Compounds; Calorimetry; Circular Dichroism; Fluorescence; Glutathione; Humans; Models, Molecular; Particle Size; Protein Binding; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Quantum Dots; Serum Albumin; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

The present work describes synthesis of water soluble L-cysteine-functionalized CdTe quantum dots (QDs) with size tunable emission at different time intervals for chitosan based film. The characterization of the synthesized CdTe QDs-chitosan film was made by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and scanning electron microscope (SEM). The optical property of CdTe QDs-chitosan film was determined by UV-vis and photo-luminescence (PL) spectroscopy whereas their antibacterial activity was screened for Gram positive (Staphylococcus aureus) as well as Gram negative (Pseudomonas aurigionasa and Escherichia coli) bacteria by disc diffusion method. The loss of tunable light emission effect of QDs as well as the positive result of antibacterial study reveals that the synthesized QDs based chitosan film is a promising candidate for wide range of biomedical applications.

Topics: Anti-Bacterial Agents; Cadmium Compounds; Calorimetry, Differential Scanning; Chitosan; Cysteine; Escherichia coli; Luminescence; Microbial Sensitivity Tests; Microscopy, Electron, Scanning; Pseudomonas aeruginosa; Quantum Dots; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Staphylococcus aureus; Tellurium; Temperature; Thermogravimetry

Quantum dots (QDs) have been used as novel fluorescent nanoprobes for various bioapplications. The degradation of QDs, and consequent release of free cadmium ions, have been suggested to be the causes of their overall toxicity. However, in contrast to sufficient investigations regarding the biological fate of QDs, a paucity of studies have reported their chemical fate in vivo. Therefore, the overall aim of our study was to understand the chemical fate of QDs in vivo and explore analytical techniques or methods that could be used to define the chemical fate of QDs in vivo.. Male ICR mice were administered a single intravenous dose (0.2 μmol/kg) of aqueous synthesized CdTe/ZnS aqQDs. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to simultaneously measure the concentrations of cadmium (Cd) and tellurium (Te) in the blood and tissues over the course of a 28 day period. We compared the blood kinetic parameters and biodistributions of Cd and Te, and used the molar ratio of Cd:Te as a marker for QDs degradation.. Cd and Te display different blood kinetics and biodistribution profiles. The Cd:Te ratio in the blood did not vary significantly within the first hour compared with intact CdTe/ZnS aqQDs. The Cd:Te ratio decreased gradually over time from the 6 h time point on. Cd accumulated in the liver, kidneys, and spleen. Te was distributed primarily to the kidneys. Sharp time-dependent increases in the Cd:Te ratio were found in liver tissues.. QDs can undergo degradation in vivo. In vitro, QDs are chemically stable and do not elicit the same biological responses or consequences as they do in vivo. Our methods might provide valuable information regarding the degradation of QDs in vivo and may enable the design and development of QDs for biological and biomedical applications.

Topics: Animals; Cadmium Compounds; Injections, Intravenous; Kidney; Liver; Male; Mass Spectrometry; Mice, Inbred ICR; Quantum Dots; Spleen; Sulfides; Tellurium; Tissue Distribution; Zinc Compounds

A stepwise chemical reaction strategy based on the specific recognition of boronic acid to diol, and N-hydroxysuccinimide (NHS) ester to amine group, was designed to construct a "signal on" electrochemiluminescence (ECL) platform for highly sensitive detection of dopamine. A boronic acid-functionalized pyrene probe was synthesized and was self-assembled on the sidewalls of carbon nanotubes via π-π stacking interactions as capture probes on a glassy carbon electrode. Meanwhile, 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP)-functionalized CdTe quantum dots (QDs) were designed as signal probes and characterized with transmission electron microscopy and spectroscopic techniques. Upon stepwise chemical reaction of dopamine with boronic acid and then DSP-QDs, the QDs were captured on the electrode as ECL emitters for signal readout, leading to an ultralow background signal. By using O2 as an endogenous coreactant, the "signal on" ECL method was employed to quantify the concentration of dopamine from 50 pM to 10 nM with a detection limit of 26 pM. Moreover, the stepwise chemical reaction-based biosensor showed high specificity against cerebral interference and was successfully applied in the detection of dopamine in cerebrospinal fluid samples. The stepwise chemical reaction strategy should be a new concept for the design of highly selective analytical methods for the detection of small biomolecules.

Topics: Cadmium Compounds; Dopamine; Electrochemical Techniques; Limit of Detection; Luminescence; Microscopy, Electron, Transmission; Quantum Dots; Spectrometry, Mass, Electrospray Ionization; Tellurium

When ligands are coordinated to quantum dots (QDs), the ring current of the ligand strongly influences the applications of the QDs, for example in solar cell technology. The Raman spectrum of the ligand can be used to probe and identify ions or measure ion concentrations. Here, we investigated, using a theoretical method, the aromaticities and Raman spectra of CdTe, CdSe, and CdS QDs coordinated with thiosalicylic acid ligands. We found that the aromaticity of the benzene ring in free thiosalicylic acid increased when it was used as a QD ligand. The ring currents of the benzene rings in the CdTe-ligand, CdSe-ligand, and CdS-ligand systems were stronger than the ring current of the benzene ring in free thiosalicylic acid; in other words, the QDs influence the ring current--they enhance the electron transfer rate of the benzene ring. We also discovered that the CdTe-ligand and CdSe-ligand systems have stronger ring currents than the CdS-ligand system. The high electronegativity and vacant d orbital of the sulfur atom influence the ring current of the ligand in the CdS-ligand system. Further, the Raman spectrum of free thiosalicylic acid was different from the spectra of the ligands in the QD-ligand systems: the Raman spectra of COO(-) in each QD-ligand system was enhanced compared with that of the COO(-) in free thiosalicylic acid.

Topics: Cadmium Compounds; Models, Theoretical; Quantum Dots; Salicylates; Selenium Compounds; Solar Energy; Spectrum Analysis, Raman; Sulfhydryl Compounds; Tellurium

In this paper, we report on the versatile self-assembly of water-soluble thiol-capped CdTe quantum dots (QDs), nanoparticles (NPs), or nanocrystals induced by L-cysteine (L-Cys). Major efforts are focused on the control of the self-organization of QDs into nanosheets (NSs), for example, by altering the solution pH and the QD size. The as-prepared nanosheets exhibit bright photoluminescence (PL) and retain the size-quantized properties of initial CdTe QDs, since they are actually formed by a 2D network of assembled QDs. By optical techniques, TEM, EDX, powder XRD, etc., it is found that the unique L-Cys-induced external destabilization is responsible for the template-free self-organization process, with the further assistance of the specific NP-NP interactions. And the internal chemical stability of initial CdTe QDs also is proven for the first time to play an important role. These results help to enhance the current understanding about the mechanism for the destabilization of colloidal NPs and their self-assembly behavior.

Topics: Cadmium Compounds; Quantum Dots; Solubility; Tellurium; Water

The bioaccumulation kinetics of thioglycolic acid stabilized CdTe quantum dots (TGA-CdTe-QDs) in a freshwater alga Ochromonas danica was comprehensively investigated. Their photoluminescence (PL) was determined by flow cytometry. Its cellular intensity increased hyperbolically with exposure time suggesting real internalization of TGA-CdTe-QDs. This hypothesis was evidenced by the nanoparticle uptake experiment with heat-killed or cold-treated cells and by their localization in the vacuoles. TGA-CdTe-QD accumulation could further be well simulated by a biokinetic model used previously for conventional pollutants. Moreover, macropinocytosis was the main route for their internalization. As limited by their diffusion from the bulk medium to the cell surface, TGA-CdTe-QD uptake rate increased proportionally with their ambient concentration. Quick elimination in the PL of cellular TGA-CdTe-QDs was also observed. Such diminishment resulted mainly from their surface modification by vacuolar biomolecules, considering that these nanoparticles remained mostly undissolved and their expulsion out of the cells was slow. Despite the significant uptake of TGA-CdTe-QDs, they had no direct acute effects on O. danica. Overall, the above research shed new light on nanoparticle bioaccumulation study and would further improve our understanding about their environmental behavior, effects and fate.

Topics: Cadmium Compounds; Fresh Water; Kinetics; Luminescent Measurements; Models, Biological; Ochromonas; Quantum Dots; Tellurium; Thioglycolates

In the present work, a flow injection (FI) "turn off-on" chemiluminescent method was developed for the determination of glutathione (GSH). Strong chemiluminescence (CL) signals were observed from the hydrogen peroxide and CdTe quantum dots (QDs) system under basic condition, addition of trace amount of Cu(Ⅱ) could caused significant CL quenching of the CdTe QDs-H2O2 system. In the presence of biothiols, Cu(Ⅱ) can be removed from CdTe QDs surface via forming Cu(Ⅱ)-S bond with thiols, and the CL signal of CdTe QDs-H2O2 system was recovered. Thus, the CL signals of CdTe QDs-H2O2 system were turned off and on by the addition of Cu(Ⅱ) and biothiols respectively, and a flow injection CL analysis system for the determination of biothiols was established. Under the optimum conditions, the CL intensity and the concentration of GSH have a good linear relationship in the range of 2.0×10(-9)-6.5×10(-7) mol L(-1) (R(2)=0.9993). The limit of detection for GSH is 1.5×10(-9) mol L(-1) (S/N=3). This method has been applied to detect GSH in human serum with satisfactory results.

Topics: Cadmium Compounds; Copper; Flow Injection Analysis; Glutathione; Humans; Hydrogen Peroxide; Luminescence; Quantum Dots; Sodium Hydroxide; Tellurium

This paper details the use of scanning photocurrent microscopy to examine localized current collection efficiency of thin-film photovoltaic devices with in-plane patterning at a submicrometer length scale. The devices are based upon two interdigitated comb electrodes at the micrometer length scale prepatterned on a substrate, with CdSe electrodeposited on one electrode and CdTe deposited over the entire surface of the resulting structure by pulsed laser deposition. Photocurrent maps provide information on what limits the performance of the windowless CdSe/CdTe thin-film photovoltaic devices, revealing "dead zones" particularly above the electrodes contacting the CdTe which is interpreted as recombination over the back contact. Additionally, the impact of ammonium sulfide passivation is examined, which enables device efficiency to reach 4.3% under simulated air mass 1.5 illumination.

Topics: Cadmium Compounds; Electrodes; Quantum Dots; Selenium Compounds; Solar Energy; Sulfides; Tellurium

The novel crystalline alloys CdTe-CuInTe2 were synthesized. The photoinduced spectral changes of the anharmonic phonon modes were explored by cw CO2 laser at power about 2 kW in the vicinity of the 1650 cm(-1) mode. The changes of the intensities for principal phonon modes were found. These modes were assigned both to harmonic as well as anharmonic modes. All the measurements are studied after the Ir illumination. The performed quantum chemical calculations with application of the norm-conserving pseudopotential method and Green functions allow to identify the origin of the content dependent anharmonic phonon modes. Some correlation between the intensities of the corresponding phonon modes at about 1600-1700 cm(-1) and the corresponding IR induced changes were found.

Topics: Alloys; Cadmium Compounds; Copper; Crystallization; Indium; Models, Molecular; Phonons; Quantum Theory; Spectroscopy, Fourier Transform Infrared; Tellurium

In this present study, we investigated thio glycolic acid-capped cadmium telluride quantum dots (TGA-CdTe QDs) as nano carrier to study the antiarthritic activity of quercetin on adjuvant induced arthritic Wistar rats. The free radical scavenging activity of QDs-QE complex was evaluated by 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO) and superoxide anion scavenging assays. Fifteen days after adjuvant induction, arthritic rats received QDs-QE complex orally at the dose of 0.2 and 0.4mg/kg daily for 3 weeks. Diclofenac sodium (DF) was used as a reference drug. Administration of QDs-QE complex showed a significant reduction in inflammation and improvement in cartilage regeneration. Treatment with QDs-QE complex significantly (P<0.05) reduced the expressions lipid peroxidation and showed significant (P<0.05) increase in activities of antioxidant enzymes such as superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx) catalase (CAT) levels in paw tissue. C-reactive protein (CRP), rheumatoid factor (RF), red blood cells (RBC) and white blood cells (WBC) count and erythrocyte sedimentation rate (ESR) of experimental animals were also estimated. Histology of hind limb tissue in experimental groups confirmed the complete cartilage regeneration in arthritis induced rats treated with QDs-QE complex. Based on our findings, we suggest that the QDs act as nano carrier for the drugs used in the treatment of various degenerative diseases.

Topics: Animals; Antioxidants; Arthritis, Experimental; Cadmium Compounds; Drug Carriers; Drug Delivery Systems; Female; Particle Size; Quantum Dots; Quercetin; Rats; Rats, Wistar; Spectrophotometry; Tellurium; Thioglycolates

Soluble inorganic nanocrystals offer a potential route to the fabrication of all-inorganic devices using solution deposition techniques. Spray processing offers several advantages over the more common spin- and dip-coating procedures, including reduced material loss during fabrication, higher sample throughput, and deposition over a larger area. The primary difference observed, however, is an overall increase in the film roughness. In an attempt to quantify the impact of this morphology change on the devices, we compare the overall performance of spray-deposited versus spin-coated CdTe-based Schottky junction solar cells and model their dark current-voltage characteristics. Spray deposition of the active layer results in a power conversion efficiency of 2.3 ± 0.3% with a fill factor of 45.7 ± 3.4%, Voc of 0.39 ± 0.06 V, and Jsc of 13.3 ± 3.0 mA/cm(2) under one sun illumination.

Topics: Cadmium Compounds; Glass; Nanoparticles; Particle Size; Solar Energy; Tellurium; Tin Compounds

The study aims at the targeted imaging using CdTe/ZnTe core shell QDs and delivery of paclitaxel (PTX) loaded fibrinogen coated yellow-QDs (PTX-fib-yellow-QDs) towards breast cancer cells via the alpha5Beta1-integrins. We developed fibrinogen coated different sized CdTe/ZnTe core shell quantum dots of 2-10 nm size, which have been prepared by one-pot aqueous-phase approach. The fib-coated-QDs (fib-coated-QDs) and PTX-fib-yellow-QDs were prepared by two-step coacervation technique using CaCl2 as cross-linker. Particle size of fib-coated-QDs was in between 60-220 nm while PTX-fib-yellow-QDs showed 180 +/- 40 nm. The MTT assay confirmed cytocompatibility of fib-coated-QDs on L929 and MCF-7 than bare QDs, whereas significant toxicity toward MCF-7 by PTX-fib-yellow-QDs was observed. The hemocompatible fib-coated-QDs showed enhanced localization and retention toward alpha5beta1-integrins +ve MCF-7 compared to alpha5beta1-integrins -ve L929 cells. The specific binding of fib-coated-yellow-QDs was further confirmed with alpha5beta1-integrins +ve HeLa and alpha5/beta1-integrins -ve HT29 cells. Cellular uptake studies revealed localization of PTX-fib-coated-yellow-QDs inside MCF-7 cells compared to the normal L929 cells. These results indicated that fib-coated-QDs could be used for targeted imaging and as a suitable "nanocarrier" aiming breast cancer cells.

Topics: Animals; Antineoplastic Agents, Phytogenic; Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; Diffusion; Female; Fibrinogen; Humans; Mice; Nanocapsules; Paclitaxel; Tellurium; Zinc

We describe here a simple fluorometric assay for the highly sensitive detection of caspase-3 activities on the basis of the inner-filter effect of gold nanoparticles (AuNPs) on CdTe quantum dots (QDs). The method takes advantage of the high molar absorptivity of the plasmon band of gold nanoparticles as well as the large absorption band shift from 520 to 680 nm upon nanoparticle aggregation. When labeled with a peptide possessing the caspase-3 cleavage sequence (DEVD), the monodispersed Au-Ps (peptide-modified AuNPs) exhibited a tendency to aggregate when exposed to caspase-3, which induced the absorption band transition from 520 to 680 nm and turned on the fluorescence of the CdTe QDs for caspase-3 sensing. Under optimum conditions, a high sensitivity towards caspase-3 was achieved with a detection limit as low as 18 pM, which was much lower than the corresponding assays based on absorbance or other approaches. Overall, we demonstrated a facile and sensitive approach for caspase-3 detection, and we expected that this method could be potentially generalized to design more fluorescent assays for sensing other bioactive entities.

Topics: Absorption; Biosensing Techniques; Cadmium Compounds; Caspase 3; Gold; Humans; Metal Nanoparticles; Quantum Dots; Tellurium

The properties of the Te-antisite defect in the neutral state in CdTe were examined using ab initio calculations. The influence of three types of deformations (1D, 2D and 3D) on the defect energy levels and formation energies was investigated. It was found that the 2D deformation is the most effective for pushing the defect levels towards the band edges and opening up the bandgap of the semiconductor, and hence may improve the performance of CdTe as a detector material. We studied the defect levels and their occupancies including Jahn-Teller distortions. The Jahn-Teller distorted configuration places the 2A1(a) defect level closer to the valence band and this defect level position coincides with the 'unknown deep donor' measured in some experiments. Partial densities of states and band structures have been analysed to understand the arrangement of the defect bonds.

Topics: Cadmium Compounds; Computer Simulation; Elastic Modulus; Electron Transport; Energy Transfer; Models, Chemical; Models, Molecular; Tellurium

Near-infrared (NIR, 700-900 nm) fluorescent quantum dots are highly promising as NIR bioprobes for high-resolution and high-sensitivity bioimaging applications. In this article, we present a class of NIR-emitting CdTe/CdS/ZnS core-shell-shell quantum dots (QDs), which are directly prepared in aqueous phase via a facile microwave synthesis. Significantly, the prepared NIR-emitting QDs possess excellent aqueous dispersibility, strong photoluminescence, favorable biocompatibility, robust storage-, chemical-, and photo-stability, and finely tunable emission in the NIR range (700-800 nm). The QDs are readily functionalized with antibodies for use in immunofluorescent bioimaging, yielding highly spectrally and spatially resolved emission for in vitro and in vivo imaging. In comparison to the large size of 15-30 nm of the conventional NIR QDs, the extremely small size (≈ 4.2 nm or 7.5 nm measured by TEM or DLS, respectively) of our QDs offers great opportunities for high-efficiency and high-sensitivity targeted imaging in cells and animals.

Topics: Animals; Cadmium Compounds; HeLa Cells; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms; Optical Imaging; Quantum Dots; Solubility; Sulfides; Tellurium; Water; Zinc Compounds

Diagnostic X-ray equipment was used to develop an experimental apparatus for calibrating a CdTe detector. Powder-type samples were irradiated with collimated X-rays. On excitation of the atoms, characteristic X-rays were emitted. We prepared Nb2O5, SnO2, La2O3, Gd2O3, and WO3 metal oxide samples. Experiments using the diagnostic X-ray equipment were carried out to verify the practicality of our apparatus. First, we verified that the collimators involving the apparatus worked well. Second, the X-ray spectra were measured using the prepared samples. Finally, we analyzed the spectra, which indicated that the energy calibration curve had been obtained at an accuracy of ±0.06 keV. The developed apparatus could be used conveniently, suggesting it to be useful for the practical training of beginners and researchers.

Topics: Cadmium Compounds; Calibration; Equipment Design; Metals; Oxides; Radiography; Tellurium

Fluorescent quantum dots (QDs) have been widely applied in biological and biomedical areas, but relatively little is known about the interaction of QDs with some natural enzymes. Herein, the interactions between 3-mercaptopropionic acid-capped CdTe QDs (MPA-QDs) and papain were systematically investigated by UV-Vis absorption spectra, fluorescence spectra and circular dichroism (CD) spectra under the physiological conditions. The fluorescence spectra results indicated that MPA-QDs quenched the fluorescence intensity of papain. The modified Stern-Volmer quenching constant K a at different temperatures and the corresponding thermodynamic parameters ΔH, ΔG and ΔS were also calculated. The binding of MPA-QDs and papain is a result of the formation of QDs-papain complex and the electrostatic interactions play a major role in stabilizing the complex. The CD technique was further used to analyze the conformational changes of papain induced by MPA-QDs and the results indicated that the biological activity of papain was affected by MPA-QDs dramatically.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Circular Dichroism; Kinetics; Papain; Protein Binding; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Temperature

We prepared and studied novel fluorescent nanocomposites based on gambogic acid (GA) and cadmium-tellurium (CdTe) quantum dots (CdTe QDs) modified with cysteamine for purpose of cancer cell labeling and combined treatment. The nanocomposites were denoted as GA-CdTe. Characterization results indicated that the CdTe QDs can readily bind onto cell plasma membranes and then be internalized into cancer cells for real-time labeling and tracing of human liver hepatocellular carcinoma cell line (HepG2) cells. GA-CdTe significantly enhanced drug accumulation in HepG2 cells and inhibited cancer cell proliferation. GA-CdTe nanocomposites also improved the drug action of GA molecules in HepG2 cells and induced the G2/M phase arrest of the cancer cell cycle, promoting cell apoptosis. Given the sensitive, pH-triggered release of GA-CdTe, the side effects of GA anticancer agents on normal cells/tissues in the blood circulation markedly decreased. Efficient drug release and accumulation in target tumor cells were also facilitated. Thus, the fluorescent GA-CdTe offered a new strategy for potential multimode cancer therapy and provided new channels for research into naturally-active compounds extracted from traditional Chinese medicinal plants.

Topics: Antineoplastic Agents; Apoptosis; Cadmium Compounds; Cell Proliferation; Cell Survival; Combined Modality Therapy; Drug Synergism; Hep G2 Cells; Humans; Microscopy, Fluorescence; Nanoparticles; Neoplasms, Experimental; Quantum Dots; Staining and Labeling; Tellurium; Xanthones

For high-sensitivity brain imaging, we have developed a two-head single-photon emission computed tomography (SPECT) system using a CdTe semiconductor detector and 4-pixel matched collimator (4-PMC). The term, '4-PMC' indicates that the collimator hole size is matched to a 2 × 2 array of detector pixels. By contrast, a 1-pixel matched collimator (1-PMC) is defined as a collimator whose hole size is matched to one detector pixel. The performance of the higher-sensitivity 4-PMC was experimentally compared with that of the 1-PMC. The sensitivities of the 1-PMC and 4-PMC were 70 cps/MBq/head and 220 cps/MBq/head, respectively. The SPECT system using the 4-PMC provides superior image resolution in cold and hot rods phantom with the same activity and scan time to that of the 1-PMC. In addition, with half the usual scan time the 4-PMC provides comparable image quality to that of the 1-PMC. Furthermore, (99m)Tc-ECD brain perfusion images of healthy volunteers obtained using the 4-PMC demonstrated acceptable image quality for clinical diagnosis. In conclusion, our CdTe SPECT system equipped with the higher-sensitivity 4-PMC can provide better spatial resolution than the 1-PMC either in half the imaging time with the same administered activity, or alternatively, in the same imaging time with half the activity.

Topics: Adult; Brain; Cadmium Compounds; Humans; Image Processing, Computer-Assisted; Male; Phantoms, Imaging; Semiconductors; Sensitivity and Specificity; Tellurium; Tomography, Emission-Computed, Single-Photon; Young Adult

Novel CdTe/CdS/SiO2 core/multishell fluorescent composite nanoparticles were prepared by reverse microemulsion method in this paper. Water-soluble CdTe/CdS core/shell quantum dots (QDs) were synthesized with 3-mercaptopropionic acid as the stabilizers and thiourea as the sulphur source in aqueous solution. CdTe/CdS/SiO2 fluorescent nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) at room temperature in cyclohexane solution when polyethylene glycol tert-octylphenyl ether (Triton X-100) as the surfactant and n-hexanol as the co-surfactant. The resultant core/multishell fluorescent composite nanoparticles were inert and chemically stable in harsh environments because of the silica layer. In this paper, the diameter of these particles was about 64 nm, and the maximum emission was about 678 nm. The coating of silica could provide a great convenience for the biological functionalization of the surface of luminescent QDs and be useful to label biological molecules in vitro and vivo in the biological analyses.

Topics: Cadmium Compounds; Microscopy, Electron, Transmission; Nanoparticles; Silicon Dioxide; Sulfides; Tellurium

This work presented a novel strategy for the synthesis of the hybrid structure silica/CdTe/molecularly imprinted polymer (Si-NP/CdTe/MIP) to recognize and detect the template bovine hemoglobin (BHb). First, amino-functionalized silica nanoparticles (Si-NP) and carboxyl-terminated CdTe quantum dots (QDs) were assembled into composite nanoparticles (Si-NP/CdTe) using the EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) chemistry. Next, Si-NP/CdTe/MIP was synthesized by anchoring molecularly imprinted polymer (MIP) layer on the surface of Si-NP/CdTe through the sol-gel technique and surface imprinting technique. The hybrid structure possessed the selectivity of molecular imprinting technique and the sensitivity of CdTe QDs as well as well-defined morphology. The binding experiment and fluorescence method demonstrated its special recognition performance toward the template BHb. Under the optimized conditions, the fluorescence intensity of the Si-NP/CdTe/MIP decreased linearly with the increase of BHb in the concentration range 0.02-2.1 μM, and the detection limit was 9.4 nM. Moreover, the reusability and reproducibility and the successful applications in practical samples indicated the synthesis of Si-NP/CdTe/MIP provided an alternative solution for special recognition and determination of protein from real samples.

Topics: Adsorption; Animals; Cadmium Compounds; Cattle; Hemoglobins; Microscopy, Electron, Scanning; Molecular Imprinting; Polymers; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

MicroRNAs (miRNAs) regulate many biological processes by post-translational gene silencing. Analysis of miRNA expression profiles is a reliable method for investigating particular biological processes due to the stability of miRNA and the development of advanced sequencing methods. However, this approach is limited by the broad specificity of miRNAs, which may target several mRNAs.. In this study, we developed a method for comprehensive annotation of miRNA array or deep sequencing data for investigation of cellular biological effects. Using this method, the specific pathways and biological processes involved in Alzheimer's disease were predicted with high correlation in four independent samples. Furthermore, this method was validated for evaluation of cadmium telluride (CdTe) nanomaterial cytotoxicity. As a result, apoptosis pathways were selected as the top pathways associated with CdTe nanoparticle exposure, which is consistent with previous studies.. Our findings contribute to the validation of miRNA microarray or deep sequencing results for early diagnosis of disease and evaluation of the biological safety of new materials and drugs.

Topics: Alzheimer Disease; Cadmium Compounds; High-Throughput Nucleotide Sequencing; Humans; MicroRNAs; Oligonucleotide Array Sequence Analysis; Quantum Dots; Tellurium; Transcriptome

This study examines dose effects of cadmium telluride quantum dots (CdTe-QDs) from two commercial sources on model macrophages (J774A.1) and colonic epithelial cells (HT29). Effects on cellular immune signalling responses were measured following sequential exposure to QDs and Pseudomonas aeruginosa strain PA01. At CdTe-QD concentrations between 10(-2) and 10 µg/ml, cells exhibited changes in metabolism and morphology. Confocal imaging revealed QD internalisation and changes in cell-cell contacts, shapes and internal organisations. QD doses below 10(-2) µg/ml caused no observed effects. When QD exposures at 10(-7) to 10(-3) µg/ml preceded PA01 (10(7) bacteria/ml) challenges, there were elevated cytotoxicity (5-22%, p < 0.05) and reduced levels (two- to fivefold, p < 0.001) of nitric oxide (NO), TNF-α, KC/CXC-1 and IL-8, compared with PA01 exposures alone. These results demonstrate that exposures to sub-toxic levels of CdTe-QDs can depress cell immune-defence functions, which if occurred in vivo would likely interfere with normal neutrophil recruitment for defence against bacteria.

Topics: Animals; Cadmium Compounds; Cell Survival; Cytokines; Dose-Response Relationship, Drug; Energy Metabolism; Epithelial Cells; HT29 Cells; Humans; Intercellular Junctions; Macrophages; Mice; Microscopy, Confocal; Nitric Oxide; Particle Size; Pseudomonas aeruginosa; Quantum Dots; Tellurium; Time Factors

3MPA-CdTe QDs in aqueous dispersion was used as a fluorescent probe for the determination of lapachol, a natural naphthoquinone found in plants of the Bignoniaceae family genus Tabebuia. Working QDs dispersions (4.5×10(-8) mol L(-1) of QDs) was prepared in aqueous media containing Tris-HCl buffer pH 7.4 and methanol (10% in volume). The excitation was made at 380 nm with signal measurement at 540 nm. To establish a relationship between fluorescence (corrected to inner filter effect) and concentration of lapachol, a Stern-Volmer model was used. The linear range obtained was from 1.0×10(-5) to 1.0×10(-4) mol L(-1). The limit of detection (x(b)-3s(b)) was 8.0×10(-6) mol L(-1). The 3MPA-CdTe QDs probe was tested in the determination of lapachol in urine, previously cleansed in an acrylic polymer. The average recovery was satisfactory.

Topics: 3-Mercaptopropionic Acid; Absorption; Cadmium Compounds; Fluorescent Dyes; Humans; Naphthoquinones; Quantum Dots; Spectrometry, Fluorescence; Tellurium

This study was undertaken to evaluate the antioxidant potential of an aqueous extract from Merremia emarginata leaves because this plant has a very high flavonoid and phenol content. The in vitro antioxidant activity was measured by diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS), superoxide anion scavenging assay and lipid peroxidation activity; the total reducing capability of the plant extract indicates that this plant is a source for natural antioxidants. Furthermore, we investigated thio glycolic acid-capped cadmium telluride quantum dots (TGA-CdTe QDs) as fluorescent probes to study the antioxidant activity of the M. emarginata extract through fluorescence quenching. The antimicrobial activity was also investigated using a disc diffusion method and fluorescence microscopy. The TGA-CdTe QDs and M. emarginata complex could provide antimicrobial activity through a reactive oxygen species pathway and/or microbial endocytosis through an electrostatic attraction. Based on our findings, we suggest that the QDs act as potential probes for the in vitro antioxidant and antimicrobial activities. In addition, their cooperative effect with the plant extract indicates that QDs could be used as nanocarriers to enhance the antimicrobial capability. Further in vivo studies on the photolabelling of antioxidants with QDs will provide insights into the mechanistic pathways of secondary metabolites against various degenerative diseases.

Topics: Anti-Bacterial Agents; Antioxidants; Benzothiazoles; Biphenyl Compounds; Cadmium Compounds; Convolvulaceae; Diffusion; Escherichia coli; Flavonoids; Indicators and Reagents; Lipid Peroxidation; Microbial Sensitivity Tests; Nanoparticles; Phenols; Picrates; Plant Extracts; Plant Leaves; Quantum Dots; Spectrometry, Fluorescence; Sulfonic Acids; Superoxides; Tellurium; Thioglycolates

Fluorescent quantum dots (QDs) have attracted great attention in biological and biomedical fields. In particular, for any potential application, the interaction of QDs with some biomolecules is much important. Herein, the interactions between QDs with different sizes and human serum albumin (HSA) were systematically investigated by UV-vis absorption spectra, fluorescence spectra and circular dichroism (CD) spectra under the physiological conditions. Four sizes of CdTe QDs with maximum emission of 520 nm (green QDs, GQDs), 568 nm (yellow QDs, YQDs), 620 nm (red QDs, RQDs) and 680 nm (crimson QDs, CQDs) were tested. The fluorescence spectra results indicated that QDs could quench the fluorescence intensity of HSA effectively with a size-dependent relationship. The binding of QDs and HSA is a result of the formation of QDs-HSA complex and the electrostatic interaction plays a major role in stabilizing the complex. The modified Stern-Volmer quenching constants K(a) at different temperatures and corresponding thermodynamic parameters ΔH, ΔG and ΔS were calculated. The conformational changes of HSA induced by QDs have been analyzed by CD spectra, and the results indicated that the biological activity of HSA was weakened in the present of QDs with bigger size.

Topics: Adsorption; Cadmium Compounds; Circular Dichroism; Humans; Molecular Conformation; Quantum Dots; Serum Albumin; Tellurium; Thermodynamics

Cysteine and triethanolamine capped CdTe nanoparticles have been synthesized using a simple aqueous solution based method. This method involves the reaction of tellurium powder with sodium borohydride (NaBH(4)) in water to produce telluride ions (Te(2-)), followed by the simultaneous addition of an aqueous solution of cadmium chloride or other cadmium source (acetate, carbonate and nitrate) and solution of L-cysteine ethyl ester hydrochloride or triethanolamine. The effect of capping agent on the size, structure and morphology of the as-synthesized nanoparticles was investigated. The particles were characterized using optical spectroscopy, transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.

Topics: Ascorbic Acid; Borohydrides; Cadmium; Cadmium Compounds; Cysteine; Ethanolamines; Indicators and Reagents; Luminescence; Microscopy, Electron, Transmission; Nanoparticles; Particle Size; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Tellurium; X-Ray Diffraction

The toxicity of CdTe QDs modified with three different ligands, namely mercaptopropionic acid (MPA), N-acetyl-L-cysteine (NAC), and glutathione (GSH), were investigated via microcalorimetric, spectroscopic, and microscopic methods. The three ligand-modified QDs have nearly identical hydrodynamic size. The results of the calorimetric experiments and optical density measurements indicate that the QDs inhibited the growth of Gram-negative Escherichia coli. The toxicity order of the three QDs is MPA-CdTe QDs>GSH-CdTe QDs>NAC-CdTe QDs. The inhibitory effects of the QDs, cadmium chloride (CdCl(2)), MPA, and the CdCl(2) and MPA mixture on E. coli growth indicate that the toxicity mechanism of QDs may be related to their bacterial adhesion. When dispersed in the cell suspensions, QDs tend to have their high surface energy reduced through adsorption to the bacterial surface, as confirmed by transmission electron microscopy and inductively coupled plasma atomic emission spectroscopy results. Furthermore, the effect of QDs on the membrane fluidity and permeability was investigated. GSH-CdTe QDs have a greater effect on the membrane function of E. coli than those of MPA-CdTe and NAC-CdTe QDs. This result may be attributed to the stronger lipophilicity of GSH compared with those of MPA and NAC.

Topics: Acetylcysteine; Cadmium Compounds; Escherichia coli; Glutathione; Ligands; Particle Size; Quantum Dots; Sulfhydryl Compounds; Tellurium; Toxicity Tests

QDs have large scale application in many important areas with potential of unintentional exposure to the environment or organism during processing of a nanotechnology containing product's life cycle. In this paper, two classical electrochemical methods, cyclic voltammetry and electrochemical impedance spectroscopy were applied to investigate the influence of particle sizes of CdTe QDs on their toxicity targeted to human serum albumin (HSA) under simulative physiological conditions. The results show that the toxicity of yellow emitting QDs (YQDs) on HSA is slightly stronger than that of the green-emitting (GQDs) and red-emitting QDs (RQDs). We also compared these two classical electrochemical methods with the traditional fluorescence spectroscopy through the above results. The electrochemical methods may be more accurate and comprehensive to investigate the toxicity of QDs at the biomacromolecular level under certain conditions, though fluorescence spectroscopy is simpler and more sensitive.

Topics: Binding Sites; Cadmium Compounds; Electric Impedance; Electrochemical Techniques; Humans; Models, Molecular; Particle Size; Protein Binding; Protein Structure, Tertiary; Quantum Dots; Serum Albumin; Solutions; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

Water-soluble CdTe/CdS quantum dots (QDs) with tuneable emissions were prepared in aqueous solution at pH=6-7 via refluxing and hydrothermal treatment. The resultant CdTe/CdS QDs are stabilized with mercaptosuccinic acid (MSA) and show high fluorescence quantum yields (maximum QY is 84%). Characterization with UV-Vis, PL, XPS, XRD and TEM demonstrates a core (CdTe)-shell (CdS) structure, which leads to high fluorescence quantum yields. The effective protection from CdS shell and MSA enables CdTe QDs to be chemically stable in a pH range of 6-9 and less toxic. These merits make our CdTe/CdS QDs very promising for bio-imaging applications, as exemplified by labelling HEK 293 cells.

Topics: Cadmium Compounds; HEK293 Cells; Humans; Hydrogen-Ion Concentration; Materials Testing; Quantum Dots; Sulfides; Tellurium

Topics: Biocatalysis; Biosensing Techniques; Cadmium Compounds; Dopamine; Enzymes; Fluorescent Dyes; Hydrogels; Monophenol Monooxygenase; Quantum Dots; Tellurium

We have developed a new fluorescent probe based on direct conjugation between 1,10-phenanthroline (Phen) and water-soluble thioglycolic acid (TGA) capped CdTe quantum dots (QDs) for the detection of double-stranded DNA (dsDNA). Phen could directly adsorb onto the QDs surface by metal-affinity driven coordination, quenching the photoluminescence (PL) of QDs via the photoinduced hole transfer process; addition of dsDNA would bring the restoration of QDs PL, as Phen could intercalate into dsDNA followed by its dissociation from the QDs surface. The dependence of QDs PL on the dsDNA amount as well as temperature was utilized to investigate the Phen-dsDNA interaction. The obtained binding constant of the QD-Phen dyad was 2-3 orders of magnitude higher than that of Phen-based metal complexes. Both the binding constant and the binding site of dsDNA with Phen increased with the elevated temperature, owing to an endothermic process. At 37 °C, sensitive detection of dsDNA with a detection limit of ~3 nmol L(-1) was achieved. Therefore, the QD-molecule direct conjugation based fluorescent probe could provide an effective alternative to those based on QD-bioconjugation and QD-ionic conjugation.

Topics: Cadmium Compounds; Coordination Complexes; DNA; Kinetics; Light; Phenanthrolines; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Thermodynamics; Thioglycolates

Ordered ultrathin films based on alternate assembly of CdTe QDs and layered double hydroxide monolayers have been fabricated, which can be used as a photoluminescence temperature sensor with dual-parameter signals and high response sensitivity.

Topics: Cadmium Compounds; Hydroxides; Luminescent Measurements; Quantum Dots; Tellurium; Temperature

The synthesis of designer solid-state materials by living organisms is an emerging field in bio-nanotechnology. Key examples include the use of engineered viruses as templates for cobalt oxide (Co(3)O(4)) particles, superparamagnetic cobalt-platinum alloy nanowires and gold-cobalt oxide nanowires for photovoltaic and battery-related applications. Here, we show that the earthworm's metal detoxification pathway can be exploited to produce luminescent, water-soluble semiconductor cadmium telluride (CdTe) quantum dots that emit in the green region of the visible spectrum when excited in the ultraviolet region. Standard wild-type Lumbricus rubellus earthworms were exposed to soil spiked with CdCl(2) and Na(2)TeO(3) salts for 11 days. Luminescent quantum dots were isolated from chloragogenous tissues surrounding the gut of the worm, and were successfully used in live-cell imaging. The addition of polyethylene glycol on the surface of the quantum dots allowed for non-targeted, fluid-phase uptake by macrophage cells.

Topics: Animals; Biotechnology; Cadmium Compounds; Cell Line; Environmental Exposure; Gastrointestinal Tract; Histocytochemistry; Luminescent Agents; Macrophages; Mice; Nanotechnology; Oligochaeta; Particle Size; Quantum Dots; Tellurium

Molecular breast imaging (MBI) is a dedicated nuclear medicine breast imaging modality that employs dual-head cadmium zinc telluride (CZT) gamma cameras to functionally detect breast cancer. MBI has been shown to detect breast cancers otherwise occult on mammography and ultrasound. Currently, a MBI-guided biopsy system does not exist to biopsy such lesions. Our objective was to consider the utility of a novel conical slant-hole (CSH) collimator for rapid (<1 min) and accurate monitoring of lesion position to serve as part of a MBI-guided biopsy system.. An initial CSH collimator design was derived from the dimensions of a parallel-hole collimator optimized for MBI performed with dual-head CZT gamma cameras. The parameters of the CSH collimator included the collimator height, cone slant angle, thickness of septa and cones of the collimator, and the annular areas exposed at the base of the cones. These parameters were varied within the geometric constraints of the MBI system to create several potential CSH collimator designs. The CSH collimator designs were evaluated using Monte Carlo simulations. The model included a breast compressed to a thickness of 6 cm with a 1-cm diameter lesion located 3 cm from the collimator face. The number of particles simulated was chosen to represent the count density of a low-dose, screening MBI study acquired with the parallel-hole collimator for 10 min after a ∼150 MBq (4 mCi) injection of Tc-99m sestamibi. The same number of particles was used for the CSH collimator simulations. In the resulting simulated images, the count sensitivity, spatial resolution, and accuracy of the lesion depth determined from the lesion profile width were evaluated.. The CSH collimator design with default parameters derived from the optimal parallel-hole collimator provided 1-min images with error in the lesion depth estimation of 1.1 ± 0.7 mm and over 21 times the lesion count sensitivity relative to 1-min images acquired with the current parallel-hole collimator. Sensitivity was increased via more vertical cone slant angles, larger annular areas, thinner cone walls, shorter cone heights, and thinner radiating septa. Full width at half maximum trended in the opposite direction as sensitivity for all parameters. There was less error in the depth estimates for less vertical slant angles, smaller annular areas, thinner cone walls, cone heights near 1 cm, and generally thinner radiating septa.. A Monte Carlo model was used to demonstrate the feasibility of a CSH collimator design for rapid biopsy application in molecular breast imaging. Specifically, lesion depth of a 1-cm diameter lesion positioned in the center of a typical breast can be estimated with error of less than 2 mm using circumferential count profiles of images acquired in 1 min.

Topics: Breast; Cadmium Compounds; Equipment Design; Humans; Image-Guided Biopsy; Molecular Imaging; Radionuclide Imaging; Tellurium

Bandgap engineering of single-crystalline alloy Cd(x)Zn(1-x)Te (0 ≤ x ≤ 1) nanowires is achieved successfully through control of growth temperature and a two zone source system in a vapor-liquid-solid process. Extensive characterization using electron microscopy, Raman spectroscopy and photoluminescence shows highly crystalline alloy nanowires with precise tuning of the bandgap. It is well known that bulk Cd(x)Zn(1-x)Te is popular for construction of radiation detectors and availability of a nanowire form of this material would help to improve detection sensitivity and miniaturization. This is a step forward towards the accomplishment of tunable and predetermined bandgap emissions for various applications.

Topics: Cadmium Compounds; Crystallization; Macromolecular Substances; Materials Testing; Molecular Conformation; Nanostructures; Particle Size; Surface Properties; Tellurium; Temperature; Zinc

A novel dual-function material was synthesized by anchoring a molecularly imprinted polymer (MIP) layer on CdTe/ZnS quantum dots (QDs) using a sol-gel with surface imprinting. The material exhibited highly selective and sensitive determination of ractopamine (RAC) through spectrofluorometry and solid-phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). A series of adsorption experiments revealed that the material showed high selectivity, good adsorption capacity and a fast mass transfer rate. Fluorescence from the MIP-coated QDs was more strongly quenched by RAC than that of the non-imprinted polymer, which indicated that the MIP-coated QDs acted as a fluorescence sensing material could recognize RAC. In addition, the MIP-coated QDs as a sorbent was also shown to be promising for SPE coupled with HPLC for the determination of trace RAC in feeding stuffs and pork samples. Under optimal conditions, the spectrofluorometry and SPE-HPLC methods using the MIP-coated QDs had linear ranges of 5.00×10(-10)-3.55×10(-7) and 1.50×10(-10)-8.90×10(-8) mol L(-1), respectively, with limits of detection of 1.47×10(-10) and 8.30×10(-11) mol L(-1), the relative standard deviations for six repeat experiments of RAC (2.90×10(-9) mol L(-1)) were below 2.83% and 7.11%.

Topics: Adsorption; Animal Feed; Cadmium Compounds; Chromatography, High Pressure Liquid; Meat; Molecular Imprinting; Optical Devices; Phenethylamines; Polymers; Quantum Dots; Solid Phase Extraction; Sulfides; Tellurium; Zinc Compounds

A facile electrodeposition technique was utilized to deposit single-walled carbon nanotubes (SWNTs) with cadmium telluride (CdTe) with well-controlled size, density, surface morphology, and composition. By controlling the applied charge, the morphology of these hybrid nanostructures was altered from CdTe nanoparticles on SWNTs to SWNT/CdTe core/shell nanostructures and the composition of the CdTe nanoparticles was altered from Te-rich (29 at% Cd) to Cd-rich (79 at% Cd) CdTe by adjusting the deposition potential. The electrical and optoelectrical properties of these hybrid nanostructures showed that photo-induced current can be tuned by tailoring the conductivity type (n-type or p-type), morphology, and size of the CdTe nanostructures, with a maximum photosensitivity (ΔI/I(0)) of about 30% for SWNT/Cd-rich CdTe (n-type) core/shell nanostructures. This work demonstrates a novel approach for synthesizing metal chalcogenide/SWNT hybrid nanostructures for various electrical and optoelectrical applications.

Topics: Cadmium Compounds; Electric Conductivity; Electromagnetic Fields; Electroplating; Light; Materials Testing; Nanotubes, Carbon; Radiation Dosage; Refractometry; Tellurium

The growing demand for semiconductor [quantum dots (Q-dots)] nanoparticles has fuelled significant research in developing strategies for their synthesis and characterization. They are extensively investigated by the chemical route; on the other hand, use of microbial sources for biosynthesis witnessed the highly stable, water dispersible nanoparticles formation. Here we report, for the first time, an efficient fungal-mediated synthesis of highly fluorescent CdTe quantum dots at ambient conditions by the fungus Fusarium oxysporum when reacted with a mixture of CdCl2 and TeCl4. Characterization of these biosynthesized nanoparticles was carried out by different techniques such as Ultraviolet-visible (UV-Vis) spectroscopy, Photoluminescence (PL), X-ray Diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM) and Fourier Transformed Infrared Spectroscopy (FTIR) analysis. CdTe nanoparticles shows antibacterial activity against Gram positive and Gram negative bacteria. The fungal based fabrication provides an economical, green chemistry approach for production of highly fluorescent CdTe quantum dots.

Topics: Anti-Bacterial Agents; Bacteria; Bacterial Infections; Cadmium Compounds; Fusarium; Humans; Quantum Dots; Tellurium

Water-solubilized quantum dots have led to a promising application in cellular labeling and biological imaging. The physicochemical properties of water-solubilized quantum dots, particularly in a physiological environment, are strongly dependent on their size. In this paper, we systematically studied the stability of mercaptosuccinic acid-coated CdTe quantum dots (MSA-QDs) of about 2.3 and 5.4 nm diameters in various buffers with different pH values and under laser irradiation by fluorescence spectroscopy. It was found that larger MSA-QDs showed better stability. Size-dependent uptake of MSA-QDs by living HeLa cells was further investigated by confocal microscopy. In phosphate buffer solution, the larger MSA-QDs entered the cells mainly by endocytosis, and part of the smaller ones entered the cells by passive penetration. In cell culture medium, their uptake pathways could be changed due to the changes of their surface properties. The cytotoxicity of smaller and larger MSA-QDs was significantly decreased due to the adsorption of some biological components in the cell culture medium on the nanoparticles surface.

Topics: Cadmium Compounds; Culture Media; HeLa Cells; Humans; Microscopy, Confocal; Particle Size; Quantum Dots; Tellurium

Quantitative real-time PCR (qPCR), as an important quantitative technique for nucleic acids, has been widely used in many fields including clinical diagnosis, molecular biology, and cancer research. However, non-specific amplification products are still a frequent problem in qPCR. In this study, we investigated the effects of QDs on real-time amplification based on either SYBR Green I or EvaGreen. It was found that QDs could raise the amplification sensitivity and thus enhance the efficiency using SYBR Green I detection system. In the case of EvaGreen detection systems, addition of QDs also led to a better correlation coefficient than without QDs. EvaGreen-based system gave sharper peaks for melting curves than SYBR Green I. The experiments indicated that the polymerase activity could be partially blocked by QDs at the pre-PCR temperatures, resulting in the improvement of PCR specificity. These results indicated that CdTe QDs could be used as a descent qPCR enhancer. Good amplification fidelity in QDs-facilitated qPCR was also a plus that has not been reported elsewhere.

Topics: Benzothiazoles; Cadmium Compounds; Diamines; DNA; Electrophoresis, Agar Gel; Fluorescent Dyes; Humans; Linear Models; Organic Chemicals; Quantum Dots; Quinolines; Real-Time Polymerase Chain Reaction; Sensitivity and Specificity; Sequence Alignment; Tellurium

Quantum dots have drawn tremendous attention in the field of in vitro and small animal in vivo fluorescence imaging in the last decade. However, concerns over the cytotoxicity of their heavy metal constituents have limited their use in clinical applications. Here, we report our comparative studies on the toxicities of quantum dots (QDs) and silica coated CdTe nanoparticles (NPs) to mice after intravenous injection. The blood cells analysis showed significant increased level of white blood cells (WBCs) in groups treated with CdTe QDs as compared to the control while red blood cells (RBCs) and platelet counts were normal in treated as well as control groups. The concentration of biochemical markers of hepatic damage, alanine amino transferase (ALT) and aspartate aminotransferase (AST) were in the normal range in all the groups. However, renal function analyses of mice showed significantly increased in the concentration of blood urea nitrogen (BUN) and creatinine (CREA) in mice treated with CdTe QDs while remained within normal ranges in both the CdTe@SiO2 NPs and control group. The results of histopathology showed that the CdTe QDs caused mild nephrotoxicity while other organs were normal and no abnormalities were detected in control and CdTe@SiO2 treated group. These findings suggest that the nephrotoxicity could be minimized by silica coating which would be useful for many biomedical applications.

Topics: Animals; Cadmium Compounds; Coated Materials, Biocompatible; Dose-Response Relationship, Drug; Female; Hydrophobic and Hydrophilic Interactions; Kidney Diseases; Mice; Mice, Inbred BALB C; Nanoparticles; Quantum Dots; Silicon Dioxide; Tellurium

Binding energy of neutral (D(0)) and negatively charged (D(-)) hydrogenic impurity located at the center of the CdTe/ZnTe spherical quantum dot has been investigated. Calculations are performed under the effective mass approximation on the basis of exact solution of the Schrödinger and Poisson equations. Eigenfunctions are expressed in terms of the Whittaker and Coulomb wave functions. Calculated results show that D(0) and D(-) impurity binding energies of ground 1s, 1S(1s2) and 2p, 3P(1s2p) excited states strongly depend on CdTe/ZnTe QD size if QD radius is less than one effective Bohr radius.

Topics: Cadmium Compounds; Energy Transfer; Models, Chemical; Nanospheres; Particle Size; Quantum Dots; Tellurium; Titanium; Zinc

Cellular adaptation is the dynamic response of a cell to adverse changes in its intra/extra cellular environment. The aims of this study were to investigate the role of: (i) the glutathione antioxidant system, and (ii) the transcription factor EB (TFEB), a newly revealed master regulator of lysosome biogenesis, in cellular adaptation to nanoparticle-induced oxidative stress. Intracellular concentrations of glutathione species and activation of TFEB were assessed in rat pheochromocytoma (PC12) cells following treatment with uncapped CdTe quantum dots (QDs), using biochemical, live cell fluorescence and immunocytochemical techniques. Exposure to toxic concentrations of QDs resulted in a significant enhancement of intracellular glutathione concentrations, redistribution of glutathione species and a progressive translocation and activation of TFEB. These changes were associated with an enlargement of the cellular lysosomal compartment. Together, these processes appear to have an adaptive character, and thereby participate in the adaptive cellular response to toxic nanoparticles.

Topics: Adaptation, Physiological; Animals; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Blotting, Western; Cadmium Compounds; Cell Culture Techniques; Cell Survival; Glutathione; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Oxidative Stress; PC12 Cells; Protein Transport; Quantum Dots; Rats; Reactive Nitrogen Species; Reactive Oxygen Species; Selenium Compounds; Sulfides; Surface Properties; Tellurium; Zinc Compounds

Recently, investigations of biological toxicity of cadmium QDs and their toxic interaction with plasma proteins have attracted great interest. In this work, flavonoids were studied for the affinities for human serum albumin (HSA) in the presence and absence of CdTe G-QDs by fluorescence quenching method. CdTe G-QDs obviously enhanced the binding affinities of kaempferol, genistein and biochanin A by 3.78 to 154.88 times depending on the QDs concentration. However, the affinity of kaempferide for HSA was slightly weakened in the presence of G-QDs. The non-methylated flavonoids were more sensitive to G-QDs than their methylated forms. The affinities of kaempferide and kaempferol for HSA at first were slightly improved and then obviously decreased with increasing G-QDs concentration. For genistein, the affinities for HSA decreased with increasing G-QDs concentration. However, the G-QDs concentration showed no obvious effect on the affinity of biochanin A. The binding affinities of flavonoids for HSA improved with increasing QDs size.

Topics: Cadmium Compounds; Dose-Response Relationship, Drug; Drug Interactions; Flavonoids; Humans; Particle Size; Protein Binding; Quantum Dots; Serum Albumin; Spectrometry, Fluorescence; Tellurium

CdTe quantum dots (QDs) were prepared in an aqueous solution using various mercaptocarboxylic acids, such as 3-mercaptopropionic acid (MPA) and thioglycolic acid (TGA), as stabilizing agents. The experimental result indicated that these stabilizing agents played an important role for the properties of the QDs. Although both TGA and MPA-capped CdTe QDs exhibited the tunable photoluminescence (PL) from green to red color, the TGA-capped QDs revealed a higher PL quantum yield (QY) up to 60% than that of MPA-capped QDs (up to 50%) by using the optimum preparation conditions, such as a pH value of ~11.2 and a TGA/Cd molar ratio of 1.5. PL lifetime measurements indicate that the TGA-capped QDs exhibited a short average lifetime while the MPA-capped QDs revealed a long one. Furthermore, the average lifetime of the TGA-capped QDs increased with the increase of the QDs size, while a decreased lifetime for the MPA-capped QDs was obtained. This means that the PL lifetime depended strongly on the surface state of the CdTe QDs. These results should be utilized for the preparation and applications of QDs.

Topics: Cadmium Compounds; Carboxylic Acids; Luminescent Agents; Luminescent Measurements; Optical Phenomena; Particle Size; Quantum Dots; Tellurium; Thioglycolates; Water

This paper describes the development of a simplified and rapid method for the aqueous synthesis of quantum dots (QDs) with CdTe cores and gradient CdS external shells (CdTe/CdS QDs) aided by microwave irradiation. Several synthesis parameters, such as molar ratio of reagents, pH, reaction temperature, and reaction time, were studied in details. Under the optimized conditions, highly effective CdTe/CdS QDs could be synthesized in aqueous phase in only 15 min. In order to improve the biocompatibility of the CdTe/CdS QDs, these QDs were then interacted with carboxymethyl chitosan (CMC) so as they could be used as fluorescent probes in the aqueous phase. With the incorporation of CMC, the stability of modified QDs was found to have improved significantly (from 4 months to more than 10 months at room temperature). The photoluminescence quantum yield (PLQY) of the modified QDs could reach 75%, other parameters include a full width at half maximum of the emission (FWHM) spectrum as 40 ~ 60 nm, and an average size, estimated from electron microscopic images, as 3.5 nm. As fluorescent probes, these modified QDs were successfully used for imaging live Madin-Darby canine kidney (MDCK) cells, in which the preliminary results indicated that these modified QDs demonstrated good biocompatibility and showed promising applications for bio-labeling and imaging.

Topics: Animals; Cadmium Compounds; Cell Line; Cell Survival; Chitosan; Dogs; Fluorescent Dyes; Microwaves; Molecular Imaging; Optical Phenomena; Quantum Dots; Spectrometry, Fluorescence; Sulfides; Tellurium; Water

To investigate the metalloestrogenic effects of cadmium telluride quantum dots (QDs) in both human breast cancer cells and in vivo in mice.. Human breast cancer cells (MCF-7 cells) were utilized to study QDs, cadmium and 17β-estradiol induced estrogen-related genomic and nongenomic signaling. Female prepubescent and ovariectomized adult mice were treated with CdTe QDs to assess whether QD-induced estrogenicity would lead to uterine changes.. Our findings demonstrate that in vitro cadmium-containing QDs induce cellular proliferation, estrogen receptor α activation, and biphasic phosphorylation of AKT and ERK1/2, comparable with 17β-estradiol. Green QDs elicited a more robust estrogenic response than orange QDs. Addition of the selective estrogen receptor antagonist, ICI 182780, completely abolished all QD-induced estrogenic effects, suggesting that QD-induced estrogenic signaling is mediated via the estrogen receptor. In vivo, chronic treatment of mice with QDs led to a two- to three-fold increase in uterine weight, comparable or greater than 17β-estradiol.. These findings suggest that certain cadmium-containing nanocrystals are endocrine disruptors, whose effects can exceed those induced by ionic cadmium or 17β-estradiol.

Topics: Animals; Cadmium Compounds; Cell Line, Tumor; Cell Proliferation; Estradiol; Female; Fulvestrant; Humans; MAP Kinase Signaling System; Mice; Oncogene Protein v-akt; Phosphorylation; Quantum Dots; Receptors, Estrogen; Tellurium; Uterus

A new type of molecularly imprinted polymer (MIP)-based fluorescent artificial receptor was developed by anchoring MIP on the surface of denatured bovine serum albumin (dBSA) modified CdTe quantum dots (QDs) using the surface molecular imprinting process. The approach combined the merits of molecular imprinting technology and the fluorescent property of the CdTe QDs. The dBSA was used not only to modify the surface defects of the CdTe QDs, but also as assistant monomer to create effective recognition sites. Three different proteins, namely lysozyme (Lyz), cytochrome c (Cyt) and methylated bovine serum albumin (mBSA), were tested as the template molecules and then the receptors were synthesized by sol-gel reaction (imprinting process). The results of fluorescence and binding experiments demonstrated the recognition performance of the receptors toward the corresponding template. Under optimum conditions, the linear range for Lyz was from 1.4×10(-8) to 8.5×10(-6) M, and the detection limit was 6.8 nM. Moreover, the new artificial receptors were applied to separate and detect Lyz in real samples. This fluorescent artificial receptor may serve as a starting point in the design of highly effective synthetic fluorescent receptor for recognition of target protein.

Topics: Biosensing Techniques; Cadmium Compounds; Equipment Design; Equipment Failure Analysis; Polymers; Protein Array Analysis; Protein Denaturation; Serum Albumin, Bovine; Spectrometry, Fluorescence; Surface Properties; Tellurium

It was found that CdTe semiconductor nanocrystals (NCs) can induce a great sensitized effect on chemiluminescence (CL) emission from peroxynitrous acid (ONOOH)-Na(2)CO(3) system. CL spectra, fluorescence (FL) spectra, and the quenching effect of reactive oxygen species were used to investigate the CL reaction mechanism. The CL intensity was proportional to the concentration of nitrite in the range from 0.05 to 50μM. The detection limit (S/N=3) was 0.024μM and the relative standard deviation (RSD) for five repeated measurements of 0.5μM nitrite was 4.2%. This method has been successfully applied to determine nitrite in well water samples with recoveries of 94.0-100.5%. This was the first work for direct (not inhibition effect) determination of analytes using semiconductor NCs-based CL sensor.

Topics: Cadmium Compounds; Carbonates; Drinking Water; Equipment Design; Luminescent Measurements; Nanoparticles; Nitrites; Peroxynitrous Acid; Sensitivity and Specificity; Tellurium

A novel disposable solid-state electrochemiluminescent (ECL) biosensor was fabricated by immobilizing glucose oxidase and surface-unpassivated CdTe quantum dots (QDs) on a screen-printed carbon electrode (SPCE). The surface morphology of the biosensor was characterized with scanning electron microscopy and atomic force microscopy. With dissolved O(2) as an endogenous coreactant, QDs/SPCE showed strong ECL emission in pH 9.0 HCl-Tris buffer solution with low ECL peak potential at -0.89 V. The ECL intensity was twice that with hydrogen peroxide as coreactant at the same concentration. This phenomenon meant the ECL decreased upon consumption of dissolved O(2) and thus could be applied to the construction of oxidase-based ECL biosensors. With glucose oxidase as a model enzyme, the biosensor showed rapid response to glucose with a linear range of 0.8 to 100 μM and a detection limit of 0.3 μM. Further detection of glucose contained in human serum samples showed acceptable sensitivity and selectivity. This work provided a promising application of QDs in ECL-based disposable biosensors.

Topics: Biosensing Techniques; Buffers; Cadmium Compounds; Carbon; Chelating Agents; Disposable Equipment; Electrochemistry; Electrodes; Glucose; Humans; Hydrogen-Ion Concentration; Limit of Detection; Luminescent Measurements; Quantum Dots; Succimer; Tellurium

On the basis of flow injection analysis technology, a simple, accurate, and sensitive method has been developed for the determination of volatile phenols in environmental water samples by using CdTe/ZnSe nanocrystals as a fluorescent probe. The influences of coexisting metal ions and volatile phenol substitutes were also investigated. The method developed for analysis of volatile phenols displayed very good linearity in the range from 1.0 × 10(-8) to 4.0 × 10(-7) g L(-1), with a correlation coefficient greater than 0.995 and a detection limit down to 2.7 × 10(-9) g L(-1) (signal-to-noise ratio 3). The proposed method was successfully applied to determine the content of volatile phenols in environmental water samples, and the quantitative recoveries were 93.4-106.1%. A possible reaction mechanism for the quenching of fluorescence is discussed using UV-vis absorption spectra, fluorescence spectra, and time-resolved luminescence spectra of volatile phenols obtained by titrating a CdTe/ZnSe nanocrystal aqueous solution and zeta potential data.

Topics: Cadmium Compounds; Flow Injection Analysis; Fluorescent Dyes; Nanoparticles; Particle Size; Phenols; Selenium Compounds; Surface Properties; Tellurium; Volatile Organic Compounds; Water Pollutants, Chemical; Zinc Compounds

L-Cysteine capped CdTe nanoparticles (NPs) were synthesized in aqueous medium, and their application as fluorescence probes in the determination of paracetamol was studied. The L-cysteine capped CdTe NPs were characterized by transmission electron microscopy, X-ray diffraction spectrometry, spectrofluorometry, ultraviolet-visible and Fourier transform infrared spectrometry. Based on the distinct fluorescence quenching of CdTe fluorescence probes in the presence of paracetamol, a simple, rapid and specific method for paracetamol determination was presented. Under optimum conditions, the relative fluorescence intensity of CdTe NPs was linearly proportional to paracetamol concentration from 1.0 × 10(-8) mol/L to 1.6 × 10(-7) mol/L with a detection limit of 4.2 × 10(-9) mol/L. The proposed method was applied to detect paracetamol in commercial tablets with satisfactory results.

Topics: Acetaminophen; Cadmium Compounds; Cysteine; Fluorescent Dyes; Luminescence; Nanoparticles; Particle Size; Surface Properties; Tellurium

The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH(·) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV-vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH(·) radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH(·) may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH(·) is proposed.

Topics: Biphenyl Compounds; Cadmium Compounds; Fluorescence; Fluorometry; Free Radicals; Kinetics; Picrates; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium

A new approach to deep tissue imaging is presented based on 8 nm CdTe semiconductor quantum dots (QDs). The characteristic 800 nm emission was found to be efficiently excited via two-photon absorption of 900 nm photons. The fact that both excitation and emission wavelengths lie within the "biological window" allows for high resolution fluorescence imaging at depths close to 2 mm. These penetration depths have been used to obtain the first deep tissue multiphoton excited fluorescence image based on CdTe-QDs. Due to the large thermal sensitivity of CdTe-QDs, one may envisage, in the near future, their use in high resolution deep-tissue thermal imaging.

Topics: Cadmium Compounds; Fluorescent Dyes; HeLa Cells; Humans; Particle Size; Photons; Quantum Dots; Spectroscopy, Near-Infrared; Tellurium

Due to their unique fluorescent properties, quantum dots present a great potential for biolabelling applications; however, the toxic interactions of quantum dots with biopolymers are little known. The toxic interactions of glutathione-capped CdTe quantum dots with trypsin were studied in this paper using synchronous fluorescence spectroscopy, fluorescence emission spectra, and UV-vis absorption spectra. The interaction between CdTe quantum dots and trypsin resulted in structure changes of trypsin and inhibited trypsin's activity. Fluorescence emission spectra revealed that the quenching mechanism of trypsin by CdTe quantum dots was a static quenching process. The binding constant and the number of binding sites at 288 and 298 K were calculated to be 1.98 × 10(6) L mol(-1) and 1.37, and 6.43 × 10(4) L mol(-1) and 1.09, respectively. Hydrogen bonds and van der Waals' forces played major roles in this process.

Topics: Binding Sites; Cadmium Compounds; Glutathione; Hydrogen Bonding; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Trypsin

Nanoconjugates composed of drug molecules encapsulated in quantum dots (QDs) attract enormous attention due to their promising bioimaging and biomedical applications. Here, the anticancer efficiency of potential pharmacophore agents (o-carborane (Cb), o-carborane-C-carboxylic acid (Cbac1), and o-carborane-C(1)C(2)-dicarboxylic acid (Cbac2) coupling with cadmium telluride QDs capped with cysteamine (CA-CdTe QDs)) have been explored. Compared with free CA-CdTe QDs, the composites consisting of Cbac1/Cbac2 and safe-dosage QDs can greatly improve the inhibition efficiency toward SMMC-7721 hepatocellular carcinoma cells with the aid of our real-time cell bioelectronic sensing system and the MTT assay. The enhanced cytotoxicity correlates with increased intracellular reactive oxygen species generation and cell apoptosis. Confocal laser scanning fluorescent microscopy shows improved cellular uptake and drug distribution of the Cbac1/Cbac2-CdTe QDs nanoconjugates. This work raises the possibility that the carborane pharmacophore in combination with QDs or other anticancer drugs may be viable for efficient cancer diagnosis and chemotherapy.

Topics: Apoptosis; Cadmium Compounds; Carboxylic Acids; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Survival; Humans; Nanostructures; Tellurium

Diatom-templated noble metal (Ag, Pt, Au) and semiconductor (CdTe) nanoparticle arrays were synthesized by the attachment of prefabricated nanoparticles of defined size. Two different attachment techniques-layer-by-layer deposition and covalent linking-could successfully be applied. The synthesized arrays were shown to be useful for surface-enhanced Raman spectroscopy (SERS) of components, for catalysis, and for improved image quality in scanning electron microscopy (SEM).

Topics: Cadmium Compounds; Diatoms; Gold; Metals, Heavy; Microscopy, Scanning Probe; Nanoparticles; Platinum; Semiconductors; Silicon Dioxide; Silver; Spectrum Analysis, Raman; Surface Properties; Tellurium

In this work, the energy response functions of Si(Li), SDD and CdTe detectors were studied in the mammographic energy range through Monte Carlo simulation. The code was modified to take into account carrier transport effects and the finite detector energy resolution. The results obtained show that all detectors exhibit good energy response at low energies. The most important corrections for each detector were discussed, and the corrected mammographic x-ray spectra obtained with each one were compared. Results showed that all detectors provided similar corrected spectra, and, therefore, they could be used to accurate mammographic x-ray spectroscopy. Nevertheless, the SDD is particularly suitable for clinic mammographic x-ray spectroscopy due to the easier correction procedure and portability.

Topics: Cadmium Compounds; Lithium; Mammography; Silicon; Spectrum Analysis; Tellurium; X-Rays

A novel dual-fluorescence quantum dots (QD) nanocomposite with tuning emission wavelength and fluorescence intensity was synthesized, in which CdS and CdTe were the internal standard and probe, respectively. This nanocomposite exhibited good photobleaching and pH stability, and exhibited selective sensing for Hg(2+) with a detection limit (3SD/k) of 5.6 nM. Based on the blue background emitted by the internal standard CdS, a novel visual fluorescence detection method has been established, and can be used for the qualitative and semi-quantitative colorimetric analysis of Hg(2+).

Topics: Cadmium Compounds; Environmental Pollutants; Fluorescent Dyes; Mercury; Nanocomposites; Quantum Dots; Reference Standards; Spectrometry, Fluorescence; Sulfides; Tellurium; Thioglycolates

Functionalized CdTe quantum dots (QDs) synthesized via ion exchange demonstrated a selective response toward fluoride in aqueous solutions based on a rapid sol-gel transition that was visible to the naked eye. The fluoride-induced hydrogel exhibited excellent fluorescent performance because of the incorporation of QDs. As a result, this highly fluorescent fluoride-induced hydrogel may pave a new way to sense fluoride using a visible sol-gel transition.

Topics: Cadmium Compounds; Fluorides; Hydrogels; Quantum Dots; Siloxanes; Spectroscopy, Fourier Transform Infrared; Tellurium; Temperature

A thermo-sensitive imprinted polymer coating CdTe quantum dots was developed to prepare fluorescent thermo-sensitive protein-affinity materials, which exhibited high specific recognition ability towards target proteins.

Topics: Animals; Cadmium Compounds; Fluorescent Dyes; Molecular Imprinting; Proteins; Quantum Dots; Tellurium; Temperature

The reversible electrochemical modulation of fluorescence and selective sensing of ascorbic acid has been achieved using a DCIP-CA-CdTe QD system. Ascorbic acid could be detected over a linear range from 2.33 μM to 56.49 μM, with a detection limit of 0.50 μM.

Topics: 2,6-Dichloroindophenol; Ascorbic Acid; Cadmium Compounds; Chemistry Techniques, Analytical; Electrochemistry; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Mercaptopropionic acid (MPA) and cysteamine (Cys) capped CdTe quantum dots (QDs) were successfully prepared and used to investigate the combined influence of surface modification, size distribution, and interaction time on their cytotoxicity in human pancreatic carcinoma (PANC-1) cells. Results indicated that the smaller the size of MPA-CdTe QDs, the higher the cytotoxicity, which could be partly due to the difference of their distribution inside cells. Comparing with MPA-CdTe QDs, Cys-CdTe QDs had better cellular metabolizability and lower cytotoxicity. These QDs' cellular distribution and cytotoxicity were closely related to their interaction time with cells. Their cytotoxicity was found to be significantly enhanced with the increase of incubation time in medium. After QD treatments, the influence of recover time on the final cell viability was also dependent on the concentration and surface modification of QDs used in pretreatment. The combined influence of these factors discussed here might provide useful information for understanding and reducing the cytotoxicity of QDs in future biomedical applications.

Topics: Cadmium Compounds; Carcinoma; Cell Line, Tumor; Cell Survival; Chemistry, Physical; Fluorescent Dyes; Humans; Microscopy, Confocal; Nanotechnology; Pancreatic Neoplasms; Quantum Dots; Surface Properties; Tellurium; Tetrazolium Salts; Thiazoles

Water-soluble CdTe quantum dots of different sizes capped with thioglycolic acid (TGA-CdTe QDs) were synthesised via a microwave-assisted method. It was found that melamine could quench the fluorescence emission of TGA-CdTe QDs in aqueous solution. Based on this, a novel method for the determination of melamine has been developed. Under optimum conditions, the fluorescence intensity of TGA-CdTe QDs versus melamine concentrations gave a linear response according to the Stern-Volmer equation. The proposed method has been successfully used to detect melamine in liquid milk with a detection limit of 0.04 mg L⁻¹, and the whole process including sample pre-treatment could be accomplished within 30 min. The obvious merits provided by this method, such as simplicity, rapidity, low cost and high sensitivity would make it promising for on-site screening of melamine adulterant in milk products. The possible mechanism involved in the interaction of melamine with TGA-CdTe QDs is discussed.

Topics: Animals; Cadmium Compounds; Calibration; Feasibility Studies; Fluorescent Dyes; Food Contamination; Food Inspection; Hydrogen-Ion Concentration; Limit of Detection; Milk; Particle Size; Quantum Dots; Solubility; Spectrometry, Fluorescence; Surface Properties; Tellurium; Thioglycolates; Time Factors; Triazines

The inherent toxicity of unmodified Quantum Dots (QDs) is a major hindrance to their use in biological applications. To make them more potent as neuroprosthetic and neurotherapeutic agents, thioglycolic acid (TGA) capped CdTe QDs, were coated with a gelatine layer and investigated in this study with differentiated pheochromocytoma 12 (PC12) cells. The QD--cell interactions were investigated after incubation periods of up to 17 days by MTT and APOTOX-Glo Triplex assays along with using confocal microscopy.. Long term exposure (up to 17 days) to gelatinated TGA-capped CdTe QDs of PC12 cells in the course of differentiation and after neurites were grown resulted in dramatically reduced cytotoxicity compared to non-gelatinated TGA-capped CdTe QDs.. The toxicity mechanism of QDs was identified as caspase-mediated apoptosis as a result of cadmium leaking from the core of QDs. It was therefore concluded that the gelatine capping on the surface of QDs acts as a barrier towards the leaking of toxic ions from the core QDs in the long term (up to 17 days).

Topics: Animals; Apoptosis; Cadmium Compounds; Cell Differentiation; Cytoplasm; Gelatin; Neurites; PC12 Cells; Quantum Dots; Rats; Tellurium; Thioglycolates; Toxicity Tests, Chronic

People exposed to engineered nanomaterials have potential health risks associated. Human α-amylase is one of the key enzymes in the digestive system. There are few reports about the influence of quantum dots (QDs) on the digestive enzymes and their inhibition system. This work focused on the toxic effect of CdTe/CdSe QDs on the interactions between α-amylase and its natural inhibitors. Thirty-six dietary polyphenols, natural α-amylase inhibitors from food, were studied for their affinities for α-amylase in the absence and presence of CdTe/CdSe QDs by a fluorescence quenching method. The magnitudes of apparent binding constants of polyphenols for α-amylase were almost in the range of 10(5)-10(7) L mol(-1) in the presence of CdTe/CdSe QDs, which were higher than the magnitudes of apparent binding constants in the absence of CdTe/CdSe QDs (10(4)-10(6) L mol(-1)). CdTe/CdSe QDs obviously improved the affinities of dietary polyphenols for α-amylase up to 389.04 times. It is possible that the binding interaction between polyphenols and α-amylase in the presence of CdTe/CdSe QDs was mainly caused by electrostatic interactions. QDs significantly influence the digestive enzymes and their inhibition system.

Topics: alpha-Amylases; Cadmium Compounds; Digestive System; Humans; In Vitro Techniques; Kinetics; Nanotechnology; Polyphenols; Quantum Dots; Selenium Compounds; Spectrometry, Fluorescence; Static Electricity; Systems Biology; Tellurium

In this work we demonstrate progress in the colloidal synthesis of amphiphilic CdTe nanocrystals stabilized by thiolated PEG oligomers with the aim of facilitating cellular uptake of the particles. High-boiling, good coordinating solvents such as dimethylacetamide and dimethylformamide accelerate the growth of the nanoparticles yielding stable colloids of which photoluminescence maxima can be tuned to cover the region of 540-640 nm with quantum yields of up to 30%. The CdTe nanocrystals capped by thiolated methoxypolyethylene glycol are shown to penetrate through the lipid bilayer of giant unilamellar vesicles and giant plasma membrane vesicles which constitute basic endocytosis-free model membrane systems. Moreover, the penetration of amphiphilic particles through live cell plasma membranes and their ability to escape the endocytic pathway have been demonstrated.

Topics: Animals; Cadmium Compounds; Cell Membrane; CHO Cells; Cricetinae; Cricetulus; Endocytosis; Hydrophobic and Hydrophilic Interactions; Intracellular Space; Molecular Weight; Polyethylene Glycols; Quantum Dots; Tellurium; Transition Temperature; Unilamellar Liposomes

Adsorption is a promising technique for decolorization of effluents of textile dyeing industries but its application is limited due to requirement of high amounts of adsorbent required. The objective of this study was to assess the potential of cadmium telluride nanoparticles loaded onto activated carbon (CdTN-AC) for the removal of sunset yellow (SY) dye from aqueous solution. Adsorption studies were conducted in a batch mode varying solution pH, contact time, initial dye concentration, CdTN-AC dose, and temperature. In order to investigate the efficiency of SY adsorption on CdTN-AC, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion kinetic models were studied. It was observed that the pseudo-second-order kinetic model fits better than other kinetic models with good correlation coefficient. Equilibrium data were fitted to the Langmuir model. Thermodynamic parameters such as enthalpy, entropy, activation energy, and sticking probability were also calculated. It was found that the sorption of SY onto CdTN-AC was spontaneous and endothermic in nature. The proposed adsorbent is applicable for SY removal from waste of real effluents including pea-shooter, orange drink and jelly banana with efficiency more than 97%.

Topics: Adsorption; Azo Compounds; Cadmium Compounds; Charcoal; Coloring Agents; Hydrogen-Ion Concentration; Kinetics; Nanoparticles; Tellurium; Thermodynamics; Water Pollutants, Chemical; Water Purification

Highly crystalline, doped polythiophene is grown from the surfaces of CdTe quantum dots by ligand exchange of 3-thenoic acid followed by an oxidant-initiated polymerization. The facile synthesis generates a composite of highly ordered fibers, which exhibit efficient charge transfer between the polythiophene and the inorganic CdTe quantum dots.

Topics: Cadmium Compounds; Nanofibers; Nanotechnology; Polymers; Quantum Dots; Tellurium; Thiophenes

Based on the polyelectrolyte-protected CdTe quantum dots (QDs), which were prepared by self-assembling of QDs and poly-diallyldimethylammonium chloride (PDADMAC) in the help of electrostatic attraction, the strong fluorescence silica nanoparticles (QDs-PDADMAC@SiO(2)) have been prepared via a water-in-oil reverse microemulsion method. Transmission electron microscopy and Zeta potential analysis were used to characterize the as-prepared nanoparticles. All of the particles were almost spherical and there is a uniform distribution of the particle size with the average diameter about 25 nm. There is a large Zeta potential of -35.07 mV which is necessary for good monodispersity of nanoparticles solution. As compared with the QDs coated by SiO(2) (QDs@SiO(2)), the QDs-PDADMAC@SiO(2) nanoparticles have much stronger fluorescence, and their fluorescence stability could be obviously improved. Moreover, QDs-PDADMAC@SiO(2) exhibits good biological compatibility which promotes their application in cellular imaging.

Topics: Cadmium Compounds; Cell Line, Tumor; Electrolytes; Emulsions; Fluorescent Dyes; Humans; Microscopy, Fluorescence; Nanoparticles; Oils; Particle Size; Polyethylenes; Quantum Dots; Quaternary Ammonium Compounds; Silicon Dioxide; Static Electricity; Tellurium; Water

To investigate the feasibility of breast tissue composition in terms of water, lipid, and protein with a cadmium-zinc-telluride (CZT) based computed tomography (CT) system to help better characterize suspicious lesions.. Simulations and experimental studies were performed using a spectral CT system equipped with a CZT-based photon-counting detector with energy resolution. Simulations of the figure-of-merit (FOM), the signal-to-noise ratio (SNR) of the dual energy image with respect to the square root of mean glandular dose (MGD), were performed to find the optimal configuration of the experimental acquisition parameters. A calibration phantom 3.175 cm in diameter was constructed from polyoxymethylene plastic with cylindrical holes that were filled with water and oil. Similarly, sized samples of pure adipose and pure lean bovine tissues were used for the three-material decomposition. Tissue composition results computed from the images were compared to the chemical analysis data of the tissue samples.. The beam energy was selected to be 100 kVp with a splitting energy of 40 keV. The tissue samples were successfully decomposed into water, lipid, and protein contents. The RMS error of the volumetric percentage for the three-material decomposition, as compared to data from the chemical analysis, was estimated to be approximately 5.7%.. The results of this study suggest that the CZT-based photon-counting detector may be employed in the CT system to quantify the water, lipid, and protein mass densities in tissue with a relatively good agreement.

Topics: Animals; Breast; Cadmium Compounds; Calibration; Cattle; Female; Image Processing, Computer-Assisted; Mammography; Phantoms, Imaging; Photons; Reference Standards; Reproducibility of Results; Tellurium; Tomography, X-Ray Computed; Zinc

CdTe quantum dots (QDs) are nanocrystals of unique composition and properties that have found many new commercial applications; therefore, their potential toxicity to aquatic organisms has become a hot research topic. The lab study was performed to determine the developmental and behavioral toxicities to zebrafish under continuous exposure to low concentrations of CdTe QDs (1-400 nM) coated with thioglycolic acid (TGA). The results show: (1) the 120 h LC(50) of 185.9 nM, (2) the lower hatch rate and body length, more malformations, and less heart beat and swimming speed of the exposed zebrafish, (3) the brief burst and a higher basal swimming rate of the exposed zebrafish larvae during a rapid transition from light-to-dark, and (4) the vascular hyperplasia, vascular bifurcation, vascular crossing and turbulence of the exposed FLI-1 transgenic zebrafish larvae.

Topics: Abnormalities, Drug-Induced; Animals; Blood Vessels; Cadmium Compounds; Embryo, Nonmammalian; Female; Growth; Heart Rate; Larva; Male; Photoperiod; Quantum Dots; Reproduction; Swimming; Tellurium; Zebrafish

A novel flow injection nanocrystals (NCs) chemiluminescence (CL) analysis method has been established for the determination of estradiol, estriol and estrone based on the enhancement of CdTe NCs-KMnO(4) CL reaction catalyzed by sodium hexametaphosphate. Glutathione (GSH)-capped CdTe nanocrystals were synthesized in aqueous medium, and the CdTe NCs emitted at around 555 nm was selected as the light emitter in CdTe NCs-KMnO(4) chemiluminescence (CL) system. It has been found that sodium hexametaphosphate (SHMP) enhanced the CL of the CdTe NCs-KMnO(4) system and estrogens increased these CL signals again in near neutral solution. UV-visible spectra, photoluminescence (PL) spectra, transmission electron microscopy (TEM) and CL spectra were used to characterize CdTe nanoparticles and investigate the mechanism of the CL reaction. On the basis of the enhancement, a novel flow-injection CL method has been established for the determination of estrogens. Under the optimum experimental conditions, three linear relationships were obtained. The method described is simple, sensitive, and has been successfully utilized for the determination of estrogens in tap water samples.

Topics: Cadmium Compounds; Catalysis; Drinking Water; Estrogens; Luminescent Measurements; Nanoparticles; Phosphates; Potassium Permanganate; Sensitivity and Specificity; Tellurium; Water Pollutants, Chemical

Light-harvesting complex (LHCII) of the photosynthetic apparatus in plants is attached to type-II core-shell CdTe/CdSe/ZnS nanocrystals (quantum dots, QD) exhibiting an absorption band at 710 nm and carrying a dihydrolipoic acid coating for water solubility. LHCII stays functional upon binding to the QD surface and enhances the light utilization of the QDs significantly, similar to its light-harvesting function in photosynthesis. Electronic excitation energy transfer of about 50% efficiency is shown by donor (LHCII) fluorescence quenching as well as sensitized acceptor (QD) emission and corroborated by time-resolved fluorescence measurements. The energy transfer efficiency is commensurable with the expected efficiency calculated according to Förster theory on the basis of the estimated donor-acceptor separation. Light harvesting is particularly efficient in the red spectral domain where QD absorption is relatively low. Excitation over the entire visible spectrum is further improved by complementing the biological pigments in LHCII with a dye attached to the apoprotein; the dye has been chosen to absorb in the "green gap" of the LHCII absorption spectrum and transfers its excitation energy ultimately to QD. This is the first report of a biological light-harvesting complex serving an inorganic semiconductor nanocrystal. Due to the charge separation between the core and the shell in type-II QDs the presented LHCII-QD hybrid complexes are potentially interesting for sensitized charge-transfer and photovoltaic applications.

Topics: Absorption; Cadmium Compounds; Energy Transfer; Fluorescent Dyes; Light-Harvesting Protein Complexes; Pisum sativum; Quantum Dots; Selenium Compounds; Semiconductors; Sulfides; Tellurium; Zinc Compounds

Here we report a facile immunoassay for detecting a synthetic peptide fragment of neurogenin3 (amino acid sequence: SKQRRSRRKKANDRERNRMH) by harnessing the aggregation-dependent fluorescence property of antibody-conjugated CdTe quantum dots in the presence of the target.

Topics: Amino Acid Sequence; Basic Helix-Loop-Helix Transcription Factors; Cadmium Compounds; Immunoassay; Molecular Sequence Data; Nerve Tissue Proteins; Quantum Dots; Spectrometry, Fluorescence; Tellurium

A novel electrochemiluminescence (ECL) immunosensor for sensitive detection of human chorionic gonadotrophin antigen (HCG-Ag) was constructed using CdTe quantum dot functionalized nanoporous PtRu alloys (QDs@PtRu) as labels for signal amplification. In this paper, nanoporous PtRu alloy was employed as the carrier for immobilization of CdTe QDs and antibodies. Primary monoclonal antibody to alfa-HCG antigen (McAb(1)) was immobilized onto the surface of chitosan coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)/CS MNPs) by glutaraldehyde (GA) as coupling agent. Then McAb(1) could be easily separated and assembled on the surface of indium tin oxide glass (ITO) owing to their excellent magnetic properties with external magnetic forces holding the MNPs. Due to signal amplification from the high loading of CdTe QDs, 4.67-fold enhancements in ECL signal for HCG-Ag detection was achieved compared to the unamplified method (single QDs as labels). Under optimal conditions, a wide detection range (0.005~50 ng mL(-1)) and low detection limit (0.8 pg mL(-1)) were achieved through the sandwich-type immunosensor. The novel immunosensor showed high sensitivity and selectivity, excellent stability, and good reproducibility, and thus has great potential for clinical detection of HCG-Ag. In particular, this approach presents a novel class of combining bifunctional nanomaterials with preferable ECL properties and excellent magnetism, which suggests considerable potential in a wide range of applications for bioassays.

Topics: Alloys; Biomarkers, Tumor; Biosensing Techniques; Cadmium Compounds; Chitosan; Electrochemistry; Ferrosoferric Oxide; Flow Injection Analysis; Humans; Immunoassay; Luminescent Measurements; Magnets; Microspheres; Nanopores; Platinum; Quantum Dots; Ruthenium; Tellurium

To be able to label a gene and monitor its migration are key important approaches for the clinical application of cancer suicide gene therapy. Photonic nanomaterials are introduced in this work. One of the most promised suicide genes - herpes simplex virus thymidine kinase (HSV-TK) gene - is successfully linked with CdTe/CdS core/shell quantum dots (QDs) via EDC/NHS coupling method. From confocal microscopy it was demonstrated that plasmid TK intracellular trafficking can be effectively and distinctly traced via monitoring the luminescence of the QDs up to 96 h after transfection of QDs-TK conjugates into Hela cells. MTT results show that the QDs-TK conjugates have a high efficient cytotoxicity after adding GCV into Hela cells, whereas the QDs exert no detectable deleterious effects on the cellular processes. The apoptosis induced by QDs-TK conjugates with GCV is distinctly traced partly due to the strong luminescence of the QDs. Our results indicate that photonic nanomaterials, e.g. QDs, provide a tool for monitoring TK gene delivery and anti-cancer activity.

Topics: Antineoplastic Agents; Cadmium Compounds; Cell Death; Cell Shape; Cell Survival; Electrophoresis, Agar Gel; Ganciclovir; Genes, Transgenic, Suicide; Genetic Therapy; HeLa Cells; Humans; Neoplasms; Quantum Dots; Reproducibility of Results; Simplexvirus; Solubility; Sulfides; Tellurium; Thymidine Kinase; Transfection; Water

To investigate the effects of CdTe QDs (cadmium telluride quantum dots) on oxidative stress and DNA damage of liver cells in mice.. Thirty ICR male mice were randomly divided into 5 groups: one negative control (normal saline) group. Three CdTe QDs groups (exposed by intravenous injection of 0.2 ml of CdTe QDs at the concentration of 3.75, 37.5 and 375 nmol/ml respectively) for electron paramagnetic resonance (EPR) test, and another positive control group (exposed by intravenous injection of 0.2 ml of cyclophosphamide 20 mg/ml) for single cell gel electrophoresis (SCGE) test. All mice were decapitated 24h after the injection, free radicals and DNA damage of liver cells were detected by EPR and SCGE.. The levels of oxygen free radicals detected by EPR were increased with the increase of CdTe QDs. The tail length, olive tail moment, tail DNA (%) and the ratio of tail/head examined by SCGE were also increased with the increase of the dosage of CdTe QDs (P < 0.01).. CdTe QDs could induce oxidative stress and DNA damage of liver cells in mice with a dose-effect relationship.

Topics: Animals; Cadmium Compounds; DNA Damage; Hepatocytes; Male; Mice; Mice, Inbred ICR; Oxidative Stress; Quantum Dots; Tellurium

We here report an efficient and enhanced fluorescence energy transfer system between confined quantum dots (QDs) by entrapping CdTe into the mesoporous silica shell (CdTe@SiO₂) as donors and gold nanoparticles (AuNPs) as acceptors. At pH 6.50, the CdTe@SiO₂-AuNPs assemblies coalesce to form larger clusters due to charge neutralization, leading to the fluorescence quenching of CdTe@SiO₂ as a result of energy transfer. As compared with the energy transfer system between unconfined CdTe and AuNPs, the maximum fluorescence quenching efficiency of the proposed system is improved by about 27.0%, and the quenching constant, K(sv), is increased by about 2.4-fold. The enhanced quenching effect largely turns off the fluorescence of CdTe@SiO₂ and provides an optimal "off-state" for sensitive "turn-on" assay. In the present study, upon addition of melamine, the weak fluorescence system of CdTe@SiO₂-AuNPs is enhanced due to the strong interactions between the amino group of melamine and the gold nanoparticles via covalent bond, leading to the release of AuNPs from the surfaces of CdTe@SiO₂; thus, its fluorescence is restored. A "turn-on" fluorimetric method for the detection of melamine is proposed based on the restored fluorescence of the system. Under the optimal conditions, the fluorescence enhanced efficiency shows a linear function against the melamine concentrations ranging from 7.5 × 10⁻⁹ to 3.5 × 10⁻⁷ M (i.e., 1.0-44 ppb). The analytical sensitivity is improved by about 50%, and the detection limit is decreased by 5.0-fold, as compared with the analytical results using the CdTe-AuNPs system. Moreover, the proposed method was successfully applied to the determination of melamine in real samples with excellent recoveries in the range from 97.4 to 104.1%. Such a fluorescence energy transfer system between confined QDs and AuNPs may pave a new way for designing chemo/biosensing.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Food Contamination; Food Inspection; Gold; Metal Nanoparticles; Quantum Dots; Silicon Dioxide; Tellurium; Triazines

We report a new class of derivatized 4,4'-bipyridinium ligands for use in synthesizing highly fluorescent, extremely stable, water-soluble CdSe and CdTe quantum dots (QDs) for bioconjugation. We employed an evaporation-condensation technique, also known as solvated metal atom dispersion (SMAD), followed by a digestive ripening procedure. This method has been used to synthesize both metal nanoparticles and semiconductors in the gram scale with several stabilizing ligands in various solvents. The SMAD technique comprised evaporation condensation and stabilization of CdSe or CdTe in tetrahydrofuran. The as-prepared product was then digestively ripened in both water and dimethyl formamide, leading to narrowing of the particle size distributions. The ligands were synthesized by nucleophilic substitution (S(N)2) reactions using 4,4'-bipyridine as a nucleophile. Confocal microscopy images revealed the orange color of the nanocrystalline QDs with diameters of ~5 nm. The size has been confirmed by using transmission electron microscopy. As a part of our strategy, 85% of the 4,4'-bipyridinium salt was synthesized as propionic acid derivative and used to both stabilize the QDs in water and label basic amino acids and different biomarkers utilizing the carboxylic acid functional group. Fifteen percent of the 4,4'-bipyridinium salt was synthesized as N-propyl maleimide and used as a second ligand to label any protein containing the amino acid cysteine by means of a 1,4-Michael addition.

Topics: Cadmium Compounds; Chemistry Techniques, Synthetic; Ligands; Pyridines; Quantum Dots; Selenium Compounds; Solvents; Tellurium; Time Factors; Water

Thiol stabilized CdTe quantum dot (QD) nanoparticles were synthesized in aqueous phase and were used as energy donors to tetra-triethyleneoxythia substituted aluminum, gallium and indium phthalocyanines through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to phthalocyanines upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizer on the QDs was observed. As a result of the nanoparticle and the phthalocyanine mixing, the photoluminescence efficiency of the phthalocyanine moieties in the mixtures does not strictly follow the quantum yields of the bare phthalocyanines. The photochemistry study of phthalocyanines in the presence of the QDs revealed high singlet oxygen quantum yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy of cancer. The fluorescence of the CdTe quantum dots-phthalocyanine conjugates (QDs-Pc) were effectively quenched by addition of 1,4-benzoquinone.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Indoles; Isoindoles; Photosensitizing Agents; Quantum Dots; Sulfhydryl Compounds; Tellurium

The enzyme α-L-fucosidase (AFu) plays an important role in the diagnosis of hepatocellular carcinoma (HCC) and fucosidosis. In this paper, a simple, sensitive and precise method based upon measuring the fluorescence quenching of CdTe semiconductor quantum dots (QDs) was developed for detecting the enzymatic activity of AFu. The detection limit of AFu was 0.01 U/L (n = 3) and the linear relationship was 0.01-4 U/L. The selectivity experiment indicated excellent selectivity for AFu over a number of interfering species. We have also studied the detection mechanism of AFu by X-ray photoelectron spectroscopy (XPS) and found that the quenching effect was caused by the oxidation of tellurium by 2-chloro-4-nitrophenol (2-CNP) which produced in AFu catalytic reaction. Moreover, the AFu sensor based on QDs was used satisfactorily for the assessment of AFu activity in serum samples. It will most probably be applicable in assembling diagnostic microdevice to realize the rapid clinic analysis of AFu.

Topics: alpha-L-Fucosidase; Cadmium Compounds; Carcinoma, Hepatocellular; Fucosidosis; Humans; Limit of Detection; Liver Neoplasms; Quantum Dots; Spectrometry, Fluorescence; Tellurium

We developed a novel chitosan-based luminescent/magnetic hybrid nanoparticles with folate-conjugated tetrapeptide composites (CLMNPs-tetrapeptide-FA) by conjugation in situ. First, chitosan, CdTe quantum dots (QDs), and superparamagnetic iron oxide were directly gelled into ternary hybrid nanogels. Subsequently, tetrapeptides (GFFG and LGPV) and folate were conjugated orderly into the hybrid nanoparticles. The morphology, composition, and properties of the as-prepared copolymers have also been characterized and determined using TEM, EDX, XRD, FTIR spectra, DLS, fluorescence spectroscopy, VSM, and fluorescence microscopy imaging studies. The size range of the end product CLMNPs-tetrapeptide-FA copolymers was from 150 to 190 nm under simulated physiological environment. In vivo, the experimental results of magnetic accumulation showed that the copolymers could be trapped in the tumor tissue under magnetic guidance. Under the present experimental conditions, the loading efficiencies of CPT were approximately 8.6 wt % for CLMNPs-GFFG-FA and 1.1 wt % for CLMNPs-LGPV-FA, respectively. The CPT cumulative release under dialysis condition mainly occurred for the first 28 h, and could reach 55% at pH 5.3 and 46% at pH 7.4 from CPT-loaded CLMNPs-GFFG-FA, and 69% at pH 5.3 and 57% at pH 7.4 from CPT-loaded CLMNPs-LGPV-FA within 28 h, respectively. The hemolysis percentages (<2%) and coagulation properties of blank and CPT-loaded copolymers were within the scope of safe values. Compared to free CPT, the CPT-loaded CLMNPs-tetrapeptide-FA copolymers showed specific targeting to A549 cells in vitro. More than 75% viability in L02 cells were seen in CLMNPs-GFFG-FA and CLMNPs-LGPV-FA copolymer concentration of 500 μg/mL, respectively. It was found that the two kinds of copolymers were transported into the A549 cells by a folate-receptor-mediated endocytosis mechanism. These results indicate that the multifunctional CLMNPs-tetrapeptide-FA copolymers possess a moderate CPT loading efficiency, low cytotoxicity, and favorable biocompatibility, and are promising candidates for tumor-targeted drug delivery.

Topics: Antineoplastic Agents, Phytogenic; Cadmium Compounds; Camptothecin; Cell Line, Tumor; Chitosan; Drug Delivery Systems; Folic Acid; Humans; Luminescence; Luminescent Agents; Magnetite Nanoparticles; Micelles; Neoplasms; Oligopeptides; Quantum Dots; Tellurium

We have successfully synthesized GSH and TGA co-capped CdTe quantum dots (QDs) with good biological compatibility and high fluorescence intensity. The effects of different reaction time, temperature, pH value, ligand concentration and the molar ratio of GSH/TGA were carefully investigated to optimize the synthesis condition. The optical properties of as-prepared CdTe QDs were studied by UV-visible absorption spectrum and fluorescence spectrum, meanwhile their structure and morphology were characterized using transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR) and X-ray powder diffraction (XRD). Compared with the CdTe QDs that are single-capped with either GSH or TGA, the GSH-TGA co-capped CdTe QDs demonstrated significantly improved fluorescence intensity and optical stability. In addition, GSH-TGA co-capped CdTe QDs were conjugated to amonoclonal antibody ND-1. The GSH-TGA co-capped CdTe QDs-antibody probe was successfully used to label colorectal cancer cells, CCL187, in vitro.

Topics: Cadmium Compounds; Colorectal Neoplasms; Glutathione; Hot Temperature; Humans; Molecular Imaging; Quantum Dots; Tellurium; Thioglycolates

CdTe/CdS core(small)/shell(thick) quantum dots (QDs) with tunable near-infrared fluorescence were directly synthesized in aqueous phase through a facile one-step strategy. The QDs possessed bright fluorescence, ultrasmall size, excellent photostability and good biocompatibility. Their applicability for biological imaging was demonstrated with the in vivo active tumor targeting of nude mice.

Topics: Animals; Cadmium Compounds; Fluorescent Dyes; Mice; Mice, Nude; Neoplasms; Quantum Dots; Sulfides; Tellurium

This work designs an enzyme-stimulated nanogel aggregation system for the naked-eye assays of α-amylase activity. The visible aggregation of the starch-stabilized CdTe nanogels may be accelerated by α-amylase through its efficient cleavage of glycosidic bonds in the starch network, which has been verified by the evidences from transmission electron microscopy and dynamic light scattering spectra. The required aggregation time, as validated by both the theoretical deduction and the experimental results, is inversely proportional to the enzymatic activity. Therefore a facile method has been proposed for the detection of enzyme activity, with an excellent linear range and a low detection limit. This nanogel-based protocol can be successfully applied in the fast and accurate assays of α-amylase activity in saliva samples with a satisfactory correlation with the standard protocol, suggesting its promising applications in the biomedical and clinical fields, especially in point-of-care testing.

Topics: alpha-Amylases; Cadmium Compounds; Humans; Kinetics; Light; Maltose; Nanogels; Polyethylene Glycols; Polyethyleneimine; Saliva; Scattering, Radiation; Spectrophotometry, Ultraviolet; Starch; Tellurium; Time Factors

Quantum dot thermal imaging has been used to analyse the chromatic dependence of laser-induced thermal effects inside optofluidic devices with monolithically integrated near-infrared waveguides. We demonstrate how microchannel optical local heating plays an important role, which cannot be disregarded within the context of on-chip optical cell manipulation. We also report on the thermal imaging of locally illuminated microchannels when filled with nano-heating particles such as carbon nanotubes.

Topics: Cadmium Compounds; Lasers; Microfluidic Analytical Techniques; Nanotubes, Carbon; Optical Devices; Quantum Dots; Semiconductors; Tellurium; Temperature

The approach for DNA detection was established by using a fluorescence resonance energy transfer (FRET) system, in which the energy donor was poly-diallyldimethylammonium chloride-protected quantum dots and the energy receptor was ethidium bromide (EB) inserting into the double stranded DNA. The concentration of the probe DNA, EB and NaCl was optimized. Under the optimized conditions, the FRET system has a stable signal and good reproducibility. The linear range is 7.7-61.6 nM with the correlation coefficient of 0.998 and the limit of detection is 7.7 nM. This method is simple and sensitive, and makes the label-free DNA detection come true.

Topics: Cadmium Compounds; DNA; DNA Probes; Ethidium; Fluorescence Resonance Energy Transfer; Polyethylenes; Quantum Dots; Quaternary Ammonium Compounds; Sodium Chloride; Tellurium

Here we demonstrate the aqueous synthesis of colloidal nanocrystal heterostructures consisting of the CdTe core encapsulated by CdS/ZnS or CdSe/ZnS shells using glutathione (GSH), a tripeptide, as the capping ligand. The inner CdTe/CdS and CdTe/CdSe heterostructures have type-I, quasi-type-II, or type-II band offsets depending on the core size and shell thickness, and the outer CdS/ZnS and CdSe/ZnS structures have type-I band offsets. The emission maxima of the assembled heterostructures were found to be dependent on the CdTe core size, with a wider range of spectral tunability observed for the smaller cores. Because of encapsulation effects, the formation of successive shells resulted in a considerable increase in the photoluminescence quantum yield; however, identifying optimal shell thicknesses was required to achieve the maximum quantum yield. Photoluminescence lifetime measurements revealed that the decrease in the quantum yield of thick-shell nanocrystals was caused by a substantial decrease in the radiative rate constant. By tuning the diameter of the core and the thickness of each shell, a broad range of high quantum yield (up to 45%) nanocrystal heterostructures with emission ranging from visible to NIR wavelengths (500-730 nm) were obtained. This versatile route to engineering the optical properties of nanocrystal heterostructures will provide new opportunities for applications in bioimaging and biolabeling.

Topics: Cadmium Compounds; Glutathione; Molecular Structure; Nanoparticles; Particle Size; Sulfides; Surface Properties; Tellurium; Water; Zinc Compounds

Fate and transport analysis has been performed to evaluate potential exposures to cadmium (Cd) from cadmium telluride (CdTe) photovoltaics (PV) for rainwater leaching from broken modules in a commercial building scenario. Leaching from broken modules is modeled using the worst-case scenario of total release of Cd, and residential screening levels are used to evaluate potential health impacts to on-site workers and off-site residents. A rooftop installation was considered rather than a ground-mount installation because rainwater runoff is concentrated via building downspouts in a rooftop installation rather than being dispersed across large areas in a ground-mount installation. Fate and transport of Cd from leachate to soil are modeled using equilibrium soil/soil-water partitioning. Subsequent migration to ambient air as windblown dust is evaluated with a screening Gaussian plume dispersion model, and migration to groundwater is evaluated with a dilution-attenuation factor approach. Exposure point concentrations in soil, air, and groundwater are one to six orders of magnitude below conservative (residential soil, residential air, drinking water) human health screening levels in both a California and southern Germany (Baden-Württemberg) exposure scenario. Potential exposures to Cd from rainwater leaching of broken modules in a commercial building scenario are highly unlikely to pose a potential health risk to on-site workers or off-site residents.

Topics: Air Pollutants; Cadmium Compounds; California; Environmental Exposure; Germany; Humans; Models, Chemical; Risk Assessment; Soil; Soil Pollutants; Solar Energy; Tellurium; Water Movements; Water Pollutants, Chemical

Semiconductor nanostructures produced by wet chemical synthesis are extremely heterogeneous, which makes single particle techniques a useful way to interrogate their properties. In this paper the ultrafast dynamics of single CdTe nanowires are studied by transient absorption microscopy. The wires have lengths of several micrometers and lateral dimensions on the order of 30 nm. The transient absorption traces show very fast decays, which are assigned to charge carrier trapping into surface defects. The time constants vary for different wires due to differences in the energetics and/or density of surface trap sites. Measurements performed at the band edge compared to the near-IR give slightly different time constants, implying that the dynamics for electron and hole trapping are different. The rate of charge carrier trapping was observed to slow down at high carrier densities, which was attributed to trap-state filling. Modulations due to the fundamental and first overtone of the acoustic breathing mode were also observed in the transient absorption traces. The quality factors for these modes were similar to those measured for metal nanostructures, and indicate a complex interaction with the environment.

Topics: Absorption; Cadmium Compounds; Electron Transport; Materials Testing; Nanoparticles; Particle Size; Sound; Tellurium

Polyacrylamide gel electrophoresis (PAGE) has been one of the most powerful and widely used separation techniques for complex biological samples, whose traditional detection methods include organic dye or silver staining. As a simple, convenient, and ultrasensitive detection of proteins for PAGE, a novel enhanced photoluminescent (PL) imaging method was developed. Thioglycolic acid (TGA)-capped CdTe quantum dots (QDs) and the enhanced reagent of tetramethylethylenediamine (TEMED) are introduced, achieving the direct detection of various proteins in native 1-DE, 2-DE, and SDS gels. Here, we describe the general protocol of TEMED-enhanced PL imaging by QDs, including materials, practical procedures, as well as some notes.

Topics: Blood Proteins; Cadmium Compounds; Coloring Agents; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; Ethylenediamines; Humans; Luminescence; Quantum Dots; Reference Standards; Rosaniline Dyes; Staining and Labeling; Tellurium; Thioglycolates

Based on a modular design, a novel ultrahigh-intensity nanoparticle probe was synthesized by orderly assembling supramolecular DNA/CdTe quantum dot nanowires and recognition DNA sequences on polystyrene microbeads. The probe was successfully applied to cancer cell imaging and visual detection of nucleic acids.

Topics: Cadmium Compounds; Cell Line, Tumor; Diagnostic Imaging; DNA; Humans; Molecular Probes; Nanoparticles; Nanowires; Neoplasms; Nucleic Acids; Particle Size; Polystyrenes; Quantum Dots; Surface Properties; Tellurium

This work reports an ECL immunoassay method for ultrasensitive detection of prostate protein antigen (PSA), by remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from the CdS nanoparticles (NPs) sensitized TiO(2) nanotube array (CdS-TiO(2) NTs) to the activated CdTe NPs functionalized multi-wall carbon nanotubes (CdTe-MWNTs) composite. The coupling of TiO(2) and CdS NPs results in a cathodic ECL intensity 14.7 times stronger than that of the pure TiO(2) NTs electrode, which could be efficiently quenched by the CdTe-MWNTs. The enhanced mechanism of TiO(2) NTs ECL by CdS NPs was studied in detail by cyclic voltammetry and ECL spectroscopy. The strong absorption of the CdTe-MWNTs in the wavelength range of 400-800 nm renders them highly efficient for ECL quenching labeled on anti-PSA antibody. Based on a sandwich structure, we developed an ECL immunoassay method for the sensitive and selective detection of PSA. The ECL intensity decrement was logarithmically related to the concentration of the PSA in the range of 1.0 fg mL(-1) to 10 pg mL(-1) with a detection limit of 1 fg mL(-1). Human serum samples were then tested using the proposed immunoassay with excellent correlations, suggesting that the proposed immunoassay method is of great promise in clinical screening of cancer biomarkers.

Topics: Antigens; Cadmium Compounds; Electrochemical Techniques; Humans; Male; Microscopy, Electron, Transmission; Nanotubes, Carbon; Prostate; Sulfides; Tellurium; Titanium

Synthesized nanoparticles often require fine fractionation according to shape, dimension, mass, chemical composition, charge, and other properties in order to become suitable for practical use. Quantum dots (QDs) are luminescent nanocrystals with narrow emission peaks. This property has been widely utilized for the multiplexed sensing and barcoding of microparticles. QDs with narrower emission peaks are preferred for such applications. The width of the emission peaks can be significantly reduced after purification. A newly developed preparative isotachophoretic method employs the dependence of spectral properties and electrophoretic mobility on the diameter of QDs. Separated fractions of QDs revealed narrower emission peaks (72% of the original width) and improved quantum yield (two-fold). The usefulness of the developed isotachophoresis for purification and analysis of other nanostructures, for example, plasmonic nanoparticles and nanobioconjugates, is expected, too.

Topics: Cadmium Compounds; Isotachophoresis; Nanoparticles; Particle Size; Quantum Dots; Tellurium

Topics: Biosensing Techniques; Cadmium Compounds; DNA; Fluorescence Resonance Energy Transfer; Hepatitis B virus; Microscopy, Fluorescence; Oligonucleotides; Quantum Dots; Tellurium

Homogeneous immunoassays are becoming more and more attractive for modern medical diagnosis because they are superior to heterogeneous immunoassays in sample and reagent consumption, analysis time, portability and disposability. Herein, a universal platform for homogeneous immunoassay, using human immunoglobulin (IgG) as a model analyte, has been developed. This assay relies upon the inner filter effect (IFE) of gold nanoparticles (AuNPs) on CdTe QDs fluorescence. The immunoreaction of antigen and antibody can induce the aggregation of antibody-functionalized AuNPs, and after aggregation the IFE of AuNPs on CdTe QDs fluorescence is greatly enhanced, resulting in a decrease of fluorescence intensity in the system. Based on this phenomenon, a wide dynamic range of 1-100 pg mL(-1) for determination of IgG can be obtained. The proposed method shows a detection limit of 0.3 pg mL(-1) for human IgG, which is much lower than the corresponding absorbance-based approach and compares favorably with other reported fluorescent methods. This immunoassay method is simple, rapid, cheap, and sensitive. The proposed method has been successfully applied to measuring IgG in serum samples, and the obtained results agreed well with those of the enzyme-linked immunosorbent assay (ELISA).

Topics: Absorption; Animals; Cadmium Compounds; Gold; Humans; Immunoassay; Immunoglobulin G; Metal Nanoparticles; Optical Phenomena; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Detection of micrometastases plays an important role in early-stage and recurrent cancer diagnosis. In the study, a new method of screening micrometastases of lung cancer in peripheral blood by magnetic nanoparticles (MNPs) and quantum dots (QDs) was developed to achieve early diagnosis and recurrence prevention. MNPs were prepared by combining miniemulsion polymerization and Stöber coating methods. QDs were prepared by using Cd(Ac)(2) · 2H(2)O and oxygen-free NaHTe with thioglycolic acid as the stabilizer. The carbodiimide-mediated condensation method was used to couple pan-cytokeratin (pan-ck) antibody (Ab) to the surface of the MNPs, and Lunx and SP-A Abs to the surface of the QDs. After four kinds of epithelial tumor cells were enriched by MNPs coupled with pan-ck Ab (MNP-pan-ck), lung cancer cells A549 and SPC-A-1 were successfully identified by QDs with double-labeled Abs. Finally, 32 patients with non-small cell lung cancer (NSCLC) were collected, out of 26 cases with the enriched circulating tumor cells (CTCs), 21 cases were successfully identified by QDs. Therefore, a new method was established in which MNP-pan-ck collected CTCs and QDs with double-labeled Abs could be used simultaneously to identify CTCs from NSCLC patients.

Topics: Aged; Cadmium Compounds; Carcinoma, Non-Small-Cell Lung; Case-Control Studies; Cell Line, Tumor; Female; Glycoproteins; Hep G2 Cells; Humans; Immunohistochemistry; Keratins; Leukocytes, Mononuclear; Lung Neoplasms; Magnetite Nanoparticles; Male; Middle Aged; Neoplasm Micrometastasis; Neoplastic Cells, Circulating; Phosphoproteins; Pulmonary Surfactant-Associated Protein A; Quantum Dots; Tellurium

Along with the widespread development of their bioapplications, concerns about the biosafety of quantum dots (QDs) have increasingly attracted intensive attention. This study examines the toxic effect and subcellular location of cadmium telluride (CdTe) QDs with different sizes against yeast Saccharomyces cerevisiae. The innovative approach is based on the combination of microcalorimetric, spectroscopic, electrochemical, and microscopic methods, which allows analysis of the toxic effect of CdTe QDs on S. cerevisiae and its mechanism. According to the values of the half inhibitory concentration (IC(50)), CdTe QDs exhibit marked cytotoxicity in yeast cells at concentrations as low as 80.81 nmol L(-1) for green-emitting CdTe QDs and 17.07 nmol L(-1) for orange-emitting CdTe QDs. QD-induced cell death is characterized by cell wall breakage and cytoplasm blebbing. These findings suggest that QDs with sizes ranging from 4.1 to 5.8 nm can be internalized into yeast cells, which then leads to QD-induced cytotoxicity. These studies provide valuable information for the design and development of aqueous QDs for biological applications.

Topics: Cadmium Compounds; Calorimetry; Electrochemical Techniques; Inhibitory Concentration 50; Microscopy, Confocal; Quantum Dots; Saccharomyces cerevisiae; Spectrometry, Fluorescence; Subcellular Fractions; Tellurium

A myoglobin-cadmium telluride quantum dot conjugate was constructed using an artificial heme modified with a thiol moiety as a linker. Irradiation of the myoglobin-cadmium telluride conjugate generated the photoreduced ferrous myoglobin via an electron transfer from the photoexcited quantum dot, leading to the formation of CO-bound myoglobin under a CO atmosphere.

Topics: Cadmium Compounds; Carbon Monoxide; Electron Transport; Heme; Luminescence; Models, Molecular; Myoglobin; Oxidation-Reduction; Quantum Dots; Sulfhydryl Compounds; Tellurium

The transport of polyacrylic acid capped cadmium telluride (CdTe) quantum dots (QDs), carboxylate-modified latex (CML), and bare silica nanoparticles (NPs) was studied in packed columns at various electrolyte concentrations and cation types. The breakthrough curves (BTCs) of QDs and CML particles in acid-treated Accusand showed significant amounts of increasing deposition with 0.5, 1, and 2 mM Ca(2+), but only minute deposition at 50 and 100 mM Na(+). Negligible QD and CML deposition occurred at 2mM Ca(2+) in columns packed with ultrapure quartz sand that was similar in size to the Accusand. These observations are not consistent with interpretations based on Derjaguin-Landau-Verwey-Overbeek (DLVO) calculations of interaction energies. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis demonstrated that there were regions on the acid-treated Accusand covered with small amounts of clay that were absent on the ultrapure quartz sand. A salt cleaning method was therefore used to remove the clay from the acid-treated Accusand. The BTCs of QDs and CML in this acid+salt treated Accusand exhibited much less deposition at any given Ca(2+) concentration compared to those obtained from the acid-treated sand. SEM images showed that most of the QD deposited in acid-treated Accusand occurred on clay surfaces. Unlike our results with QDs and CML, negligible deposition of bare silica NPs occurred at 5 and 10 mM Ca(2+) in acid-treated Accusand. The high deposition of QDs and CML particles was therefore attributed to bridging complexation in which Ca(2+) serves as a bridge between the cation exchange locations on the clay and carboxyl functional groups on the QD and CML particles, which were absent on the bare silica NPs. Our results suggest that the transport of carboxylic ligand-modified NPs may be limited in subsurface environments because of the ubiquitous presence of clay and divalent cations.

Topics: Acrylic Resins; Cadmium Compounds; Electrolytes; Kinetics; Microscopy, Electron, Scanning; Nanoparticles; Porosity; Quantum Dots; Silicon Dioxide; Surface Properties; Tellurium

Nitric oxide (NO) donor compounds are primarily monofunctional in that they release NO under the requisite conditions. To detect the amount and duration of NO released, subsequent analysis methods are required. It would be advantageous if a NO donor compound could both release and detect NO at the same time. This would eliminate potential errors in the analysis. In this paper, novel cadmium telluride quantum dots (CdTe QD)-carboxymethyl chitosan (CMCS) nanocomposite NO donors, including both diazeniumdiolates and fluorescence probes, were fabricated by first synthesizing CdTe QD in CMCS aqueous solution and then reacting NO as well as ethyl bromide with the resultant CdTe QD-CMCS nanocomposites. Transmission electron microscopy, scanning electron microscopy and particle size analysis were used to examine the morphology and size distribution of the CdTe QD-CMCS nanocomposite NO donors. The donors are nanospheres with CdTe QD encapsulated and have dimensions of ~300 nm. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and contact angle tests were employed to characterize the chemical structure of the donors, and the results also show that CdTe QD are well incorporated into CMCS, and many of them are close to the surface of the donors. The precursors of the donors exhibit a fluorescent effect, and the fluorescence can be quenched by NO. The donors can release NO spontaneously in a phosphate-buffered saline solution similar to a physiological environment, and can quantitatively detect the release of NO in situ based on fluorescence quenching of the donors by the NO.

Topics: Animals; Cadmium Compounds; Cell Death; Cell Survival; Chitosan; Endothelial Cells; Microscopy, Fluorescence; Nanocomposites; Nitric Oxide; Nitric Oxide Donors; Particle Size; Photoelectron Spectroscopy; Quantum Dots; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Sus scrofa; Tellurium; Water

Quantum dots (QDs) have a great potential for applications in nanomedicine. However, a few studies showed that they also exhibited toxicity. We used Escherichia coli (E. coli) as the model to study the effect of CdTe QDs on the cell growth by microcalorimetric technique, optical density (OD(600)) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra. Three size aqueous-compatible CdTe QDs with maximum emission of 543 nm (green-emitting QDs, GQDs), 579 nm (yellow-emitting QDs, YQDs) and 647 nm (red-emitting QDs, RQDs) were tested. The growth rate constants (k) and half-inhibiting concentration (IC(50)) were calculated from the microcalorimetric data. The results indicated that CdTe QDs exhibited a dose-dependent inhibitory effect on cell growth. The order of toxicity is GQDs>YQDs>RQDs. The smaller the particle size of QDs is, the more toxicity it is. ATR-FTIR spectra indicated that the outer membrane of the cell was changed or damaged by the QDs, which may induce QDs and harmful by-products to enter into the cells. These could be one of the reasons that CdTe QDs have cytotoxic effects on E. coli.

Topics: Animal Testing Alternatives; Cadmium Compounds; Escherichia coli; Inhibitory Concentration 50; Particle Size; Quantum Dots; Tellurium; Toxicity Tests

Quantum dots (QD) are semiconductor nanocrystals able to generate free radical species upon exposure to an electromagnetic radiation, usually in the ultraviolet wavelength range. In this work, CdTe QD were used as highly reactive oxygen species (ROS) generators for the control of pharmaceutical formulations containing epinephrine. The developed approach was based on the chemiluminometric monitoring of the quenching effect of epinephrine on the oxidation of luminol by the produced ROS. Due to the relatively low energy band-gap of this chalcogenide a high power visible light emitting diode (LED) lamp was used as photoirradiation element and assembled in a laboratory-made photocatalytic unit. Owing to the very short lifetime of ROS and to ensure both reproducible generation and time-controlled reaction implementation and development, all reactional processes were implemented inline by using an automated multipumping micro-flow system. A linear working range for epinephrine concentration of up to 2.28×10(-6) mol L(-1) (r=0.9953; n=5) was verified. The determination rate was about 79 determinations per hour and the detection limit was about 8.69×10(-8) mol L(-1). The results obtained in the analysis of epinephrine pharmaceutical formulations by using the proposed methodology were in good agreement with those furnished by the reference procedure, with relative deviations lower than 4.80%.

Topics: Antioxidants; Bronchodilator Agents; Cadmium Compounds; Epinephrine; Equipment Design; Light; Limit of Detection; Luminescent Agents; Luminescent Measurements; Luminol; Oxidation-Reduction; Pharmaceutical Preparations; Photochemical Processes; Quantum Dots; Reactive Oxygen Species; Tellurium

We report photocatalytic H(2) production by hydrogenase (H(2)ase)-quantum dot (QD) hybrid assemblies. Quenching of the CdTe exciton emission was observed, consistent with electron transfer from the quantum dot to H(2)ase. GC analysis showed light-driven H(2) production in the presence of a sacrificial electron donor with an efficiency of 4%, which is likely a lower limit for these hybrid systems. FTIR spectroscopy was employed for direct observation of active-site reduction in unprecedented detail for photodriven H(2)ase catalysis with sensitivity toward both H(2)ase and the sacrificial electron donor. Photosensitization with Ru(bpy)(3)(2+) showed distinct FTIR photoreduction properties, generating all of the states along the steady-state catalytic cycle with minimal H(2) production, indicating slow, sequential one-electron reduction steps. Comparing the H(2)ase activity and FTIR results for the two systems showed that QDs bind more efficiently for electron transfer and that the final enzyme state is different for the two sensitizers. The possible origins of these differences and their implications for the enzymatic mechanism are discussed.

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Catalysis; Catalytic Domain; Electron Transport; Hydrogen; Hydrogenase; Light; Models, Molecular; Oxidation-Reduction; Photochemical Processes; Quantum Dots; Tellurium; Thiocapsa roseopersicina

The quenching of quantum dots' emission by some analytes (Hg(2+), Pb(2+), etc.) has long been hindering the fabrication of QD-based 'turn-on' or ratiometric fluorescent sensors for these analytes. In this study, we demonstrate a facile solution for constructing a robust FRET-based ratiometric sensor for Hg(2+) detection in water with CdTe QDs as the donor. By using the reverse microemulsion approach, CdTe QDs were first embedded into nanosized silica particles, forming the QDs/silica cores, a positively charged ultrathin spacer layer was then deposited on each QDs/silica core, followed by the coating of a mercury ion probe on the particle surfaces. The resultant multilayered QDs/silica composite nanoparticles are dispersible in HEPES buffered water; and in the presence of mercury ions, the QDs inside the nanoparticles will not be quenched by mercury ions due to the existence of the positively charged spacer layer, but can transfer their excited energy to the acceptors (probe/Hg(2+) complex), thus achieving the FRET-based ratiometric sensing for mercury ions in totally aqueous media. With its detection limit of 260 nM, this QD-based sensor exhibits high selectivity toward mercury ion and can be used in a wide pH range. This strategy may be used to construct QDs-based ratiometric assays for other ions which quench the emission of QDs.

Topics: Cadmium Compounds; Fluorescence Resonance Energy Transfer; Hydrogen-Ion Concentration; Mercury; Quantum Dots; Silicon Dioxide; Static Electricity; Tellurium; Waste Disposal, Fluid; Water; Water Pollutants, Chemical

Four types of water-soluble luminescent quantum dots (QDs) whose surface was functionlaized with thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), or glutathione (GSH), were investigated for the sensitive and selective detection of hydroxyl radical (·OH) in aqueous media. It was found that the type of capping agent and QD influenced the sensitivity of the probe. The order of sensitivity of the probe was: GSH-CdTe@ZnS > MPA-CdTe@ZnS > TGA-CdTe > MPA-CdTe QDs. Under the optimum conditions, a limit of detection as low as 8.5 × 10(-8) M was obtained using GSH-CdTe@ZnS. The effects of foreign reactive oxygen species and the Fenton reactants and products as possible interferences on the proposed probe were negligible for CdTe@ZnS QDs. Besides, experimental results indicated that CdTe@ZnS QDs were more attractive for the selective recognition of ·OH than CdTe QDs. The mechanistic reaction pathway between the QDs and ·OH is proposed.

Topics: Buffers; Cadmium Compounds; Chemistry Techniques, Analytical; Hydrogen-Ion Concentration; Hydroxyl Radical; Optical Phenomena; Quantum Dots; Spectrometry, Fluorescence; Sulfhydryl Compounds; Sulfides; Tellurium; Zinc Compounds

The purpose of this study was to test the efficacy of cyclic Arg-Gly-Asp (RGD) peptide conjugated with polyionic complex nanomicelles as targeted therapy for glioma.. A stable cyclic RGD polyionic complex nanostructure, ie, a c(RGDfC) polyionic complex micelle, was synthesized and its biocompatibility with cultured neurons was assessed using a cell viability assay. Targeted binding to cultured glioma cells was evaluated by the CdTe quantum dot marking technique and a cell viability assay. The inhibitory effect of the nanomicelles against glioma cells was also evaluated, and their targeted migration into rat brain glioma cells and apoptotic effects were traced by the CdTe quantum dot marking and immunohistochemical staining.. c(RGDfC) polyionic complex micelles did not affect the growth of neurons but bonded selectively to and inhibited proliferation of glioma cells in vitro. When tested in vivo, the micelles migrated into glioma cells, inducing apoptosis in the rat brain.. The c(RGDfC) polyionic complex micelle is an effective targeted therapy against glioma.

Topics: Analysis of Variance; Animals; Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cadmium Compounds; Cell Proliferation; Cell Survival; Cells, Cultured; Dose-Response Relationship, Drug; Drug Delivery Systems; Glioma; Hydrogen-Ion Concentration; Immunohistochemistry; Materials Testing; Micelles; Neurons; Oligopeptides; Quantum Dots; Rats; Rats, Wistar; Tellurium; Xenograft Model Antitumor Assays

Vascular endothelium is a potential target for therapeutic intervention in diverse pathological processes, including inflammation, atherosclerosis, and thrombosis. By virtue of their intravascular topography, endothelial cells are exposed to dynamically changing mechanical forces that are generated by blood flow. In the present study, we investigated the interactions of negatively charged 2.7 nm and 4.7 nm CdTe quantum dots and 50 nm silica particles with cultured endothelial cells under regulated shear stress (SS) conditions. Cultured cells within the engineered microfluidic channels were exposed to nanoparticles under static condition or under low, medium, and high SS rates (0.05, 0.1, and 0.5 Pa, respectively). Vascular inflammation and associated endothelial damage were simulated by treatment with tumor necrosis factor-α (TNF-α) or by compromising the cell membrane with the use of low Triton X-100 concentration. Our results demonstrate that SS is critical for nanoparticle uptake by endothelial cells. Maximal uptake was registered at the SS rate of 0.05 Pa. By contrast, endothelial exposure to mild detergents or TNF-α treatment had no significant effect on nanoparticle uptake. Atomic force microscopy demonstrated the increased formation of actin-based cytoskeletal structures, including stress fibers and membrane ruffles, which have been associated with nanoparticle endocytosis. In conclusion, the combinatorial effects of SS rates, vascular endothelial conditions, and nanoparticle physical and chemical properties must be taken into account for the successful design of nanoparticle-drug conjugates intended for parenteral delivery.

Topics: Actin Cytoskeleton; Cadmium Compounds; Cell Growth Processes; Cell Membrane; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Microfluidics; Microscopy, Atomic Force; Models, Biological; Nanoparticles; Octoxynol; Quantum Dots; Silicon Dioxide; Stress, Mechanical; Tellurium; Tumor Necrosis Factor-alpha

CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

Topics: Cadmium Compounds; Microscopy, Atomic Force; Spectrophotometry; Surface Properties; Tellurium; Temperature; X-Ray Diffraction

A novel and portable strategy based on fluorescence polarization immunoassay (FPIA) using quantum dots (QDs) was described in this study for simple, rapid, and sensitive detection of carcinoembryonic antigen (CEA). Under optimal conditions, the sensor has a wide dynamic range (from 0.5 ng/mL to 200 ng/mL) and a good correlation. The limit of detection (LOD) is 0.21 ng/mL (S/N = 3). The sensor has been applied for detection of carcinoembryonic antigen in 10 human serum samples with the range of recovery from 92.1 % to 103.6 %. Furthermore, bioconjugation of the core-shell QDs with streptavidin (SA) has been successfully applied in immunofluorescent imaging of the human hepatocellular carcinoma (HEPG2) cell line. The experimental results demonstrated the successful application of QDs-based fluorescence polarization immunoassay for detection of target proteins of biomedical importance. This strategy shows great promise for clinical diagnoses and basic discovery with high sensitivity, good specificity, simple procedures and short analysis time.

Topics: Antibodies; Biophysical Phenomena; Cadmium Compounds; Calibration; Carcinoembryonic Antigen; Fluorescence Polarization Immunoassay; Hep G2 Cells; Humans; Molecular Imaging; Sulfides; Tellurium; Time Factors

Semiconductor luminescent Quantum Dots (QDs) constitute a growing area of research for biological imaging and other biomedical applications. One of the main challenges is to provide QDs with a biocompatible and easy to functionalize surface while retaining the core optical properties. Gelatine is an excellent candidate for that purpose as it is a very common natural polymer, highly biocompatible and bearing various functional groups. Here we present a simple, one-pot method for manufacturing gelatinated QDs with chosen optical properties.

Topics: Biocompatible Materials; Cadmium Compounds; Gelatin; Quantum Dots; Tellurium; Thioglycolates

Successful development of safe and effective nanoprobes for targeted imaging and selective therapy of in-situ gastric cancer is a great challenge. Herein, one kind of multifunctional HER2 monoclonal antibody conjugated RNase A-associated CdTe quantum dot cluster (HER2-RQDs) nanoprobes was prepared, its cytotoxicity was evaluated. Subcutaneous gastric cancer nude mouse models and in-situ gastric cancer SCID mouse models were established, and were intravenously injected HER2-RQDs nanoprobes, the bio-distribution and therapeutic effects of HER2-RQDs in vivo were evaluated. Results showed that HER2-RQDs nanoprobes could selectively kill gastric cancer MGC803 cells, could target imaging subcutaneous gastric cancer cells at 3 h post-injection, and in-situ gastric cancer cells at 6 h post-injection, and could inhibit the growth of gastric cancer tissues and extended survival time of gastric cancer bearing mouse models, which is closely associated with destroying functional RNAs in cytoplasm by RNase A released from HER2-RQDs nanoprobes, preventing protein synthesis and inducing cell apoptosis. High-performance HER2-RQDs nanoprobes exhibit great potential in applications such as in-situ gastric cancer targeted imaging, and selective therapy in the near future.

Topics: Animals; Antibodies, Monoclonal; Biocompatible Materials; Cadmium Compounds; Cell Line, Tumor; Cytoplasm; Diagnostic Imaging; Humans; Mice; Mice, Nude; Mice, SCID; Nanotechnology; Neoplasm Transplantation; Quantum Dots; Receptor, ErbB-2; Ribonuclease, Pancreatic; Stomach Neoplasms; Tellurium; Time Factors

This paper investigates the interactions between human serum albumin (HSA) and CdTe quantum dots (QDs) with nearly identical hydrodynamic size, but capped with four different ligands (MPA, NAC, and GSH are negatively charged; CA is positively charged) under physiological conditions. The investigation was carried out using fluorescence spectroscopy, circular dichroism (CD) spectra, UV-vis spectroscopy, and dynamic light scattering (DLS). The results of fluorescence quenching and UV-vis absorption spectra experiments indicated the formation of the complex of HSA and negatively charged QDs (MPA-CdTe, NAC-CdTe, and GSH-CdTe), which was also reconfirmed by the increasing of the hydrodynamic radius of QDs. The K(a) values of the three negatively charged QDs are of the same order of magnitude, indicating that the interactions are related to the nanoparticle itself rather than the ligands. ΔH<0 and ΔS>0 implied that the electrostatic interactions play predominant roles in the adsorption process. Furthermore, it was also proven that QDs can induce the conformational changes of HSA from the CD spectra and the three-dimensional fluorescence spectra of HSA. However, our results demonstrate that the interaction mechanism between the positively charged QDs (CA-CdTe) and HSA is significantly different from negatively charged QDs. For CA-CdTe QDs, both the static and dynamic quenching occur within the investigated range of concentrations. According to the DLS results, some large-size agglomeration also emerged.

Topics: Cadmium Compounds; Fluorescence; Humans; Kinetics; Ligands; Light; Molecular Conformation; Particle Size; Protein Binding; Protein Structure, Secondary; Quantum Dots; Scattering, Radiation; Serum Albumin; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Temperature

Quantum dots (QDs) have recently been the focus of attention of many investigators for development of diagnostic tools in many research areas. In this work, we established a new QD-based assay to evaluate the antioxidant/polyphenolic activity. This assay is based on measurement of the inhibitory effect of the antioxidant/polyphenolic compounds on the UV-induced bleaching of CdTe QDs with L-cysteine capping. QDs exhibited excellent photostability without any UV exposure, while they bleached rapidly under UV irradiation. Generation of reactive oxygen species (ROS) under UV irradiation is probably the main cause of the photobleaching of QDs. By comparing the photostability of QDs in buffer solution in the absence and presence of sodium azide, as a known (1)O(2) quencher, the involvement of (1)O(2) in photobleaching of QDs was confirmed. The photobleaching effect induced by ROS could be reduced in the presence of antioxidant/polyphenolic compounds. We tested several antioxidant/polyphenolic compounds as well as known antioxidants such as trolox and 4 different types of tea. The results obtained by the QD-based assay revealed a very good correlation with the data acquired by Folin-Ciocalteu assay. Furthermore, a deeper understanding of the mechanism and the solution for photobleaching of QDs under UV irradiation might be very meaningful in promoting their clinical applications.

Topics: Antioxidants; Cadmium Compounds; Cysteine; Oxidation-Reduction; Photobleaching; Polyphenols; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium

A simple and straightforward quantification method integrated in a fully automated multi-pumping flow system (MPFS) using water-soluble mercaptopropionic acid (MPA)-capped CdTe quantum dots (QDs) was implemented for the fluorescence quantification of N-acetyl-L-cysteine (NAC) in pharmaceutical formulations. The developed approach was based on NAC ability to establish surface interactions that result in enhanced nanocrystals fluorescence intensity, proportional to analyte concentration. Size and concentration of QDs, ageing, composition, concentration and pH of the buffer solution revealed to have a noticeable effect on the enhancing efficiency affecting sensitivity and linear working range of the methodology. Under the optimal conditions, a linear working range was obtained for NAC concentrations ranging from 50 to 750μmolL(-1) (r=0.9978), with good precision (r.s.d.<1.6%; n=5) and a sampling rate of about 75hr(-1). The detection limit (LOD) was approximately 1.6μmolL(-1). The method was applied to pharmaceutical preparations and the results revealed good agreement with those obtained by the reference procedure with relative deviations between -2.1 and +4.2%. Advantages of the new procedure include speed, low consumption of reagents, minor waste generation, requiring also much less work than the recommended HPLC method. The mechanism for luminescence enhancement of CdTe QDs is discussed. FT-IR spectra revealed that sulphydryl groups of NAC have a high affinity with the nanocrystals.

Topics: Acetylcysteine; Buffers; Cadmium Compounds; Chemistry, Pharmaceutical; Feasibility Studies; Flow Injection Analysis; Hydrogen-Ion Concentration; Kinetics; Nanoparticles; Spectrometry, Fluorescence; Surface Properties; Tellurium; Time Factors

Fluorescent quantum dots (QDs) used for biomedical imaging and diagnostics have attracted considerable attention over the past decade. Here, we report our finding regarding the therapeutic efficacy of the popularly used red/brown, brown or close to black CdTe and CdSe QDs. Upon 671-nm laser irradiation, these QDs can rapidly convert light energy into heat, both in vitro and in vivo. In the present study, the growth of mouse melanoma tumors injected with CdTe(710) QDs coated with a silica shell (SiO(2)) was significantly inhibited after laser irradiation, with eventual disappearance of the tumor. In contrast, tumors injected with the silica-coated QDs without subsequent irradiation continued to grow over time. They had a growth rate close to that of tumors injected with SiO(2) or phosphate-buffered saline, with or without laser irradiation. In conclusion, our data suggest that the popularly used CdTe and CdSe QDs have great potential in the treatment of cancer using photothermal therapy.

Topics: Animals; Cadmium Compounds; Cell Line, Tumor; Humans; Lasers; Light; Liver; Melanoma; Mice; Mice, Inbred BALB C; Optics and Photonics; Photochemistry; Quantum Dots; Reactive Oxygen Species; Selenium Compounds; Skin Neoplasms; Tellurium; Temperature; Time Factors

A new assay was developed by use of micellar electrokinetic capillary chromatography with indirect LIF fluorescence for the determination of thiamethoxam, acetamiprid, and imidacloprid residues in vegetables, in which the cadmium telluride quantum dots (QDs) synthesized in aqueous phase were used as fluorescent background substance and their excitation and emission wavelengths matched with LIF detector by engineering their size. The factors that affected the peak height and the resolution were optimized. The running buffer was composed of 4.4 μM cadmium telluride QDs as fluorescent background substance, 40 mM borate and 60 mM SDS, and its pH was adjusted to 8.0. The separation voltage was 25 kV. Under the optimum conditions, the detection limits were 0.05, 0.01, and 0.009 mg/kg; the linear dynamic ranges were 0.5-30, 0.1-30, and 0.1-30 mg/L; and the average recoveries of spiked samples were 72.0-101.2, 74.0-106.7, and 77.8-105.1% for thiamethoxam, acetamiprid, and imidacloprid, respectively. The assay can meet the requirement of maximum residue limits to these three pesticides in the regulations of European Union and Japan, and has been applied for determining their residues in vegetables.

Topics: Cadmium Compounds; Chromatography, Micellar Electrokinetic Capillary; Fluorescence; Imidazoles; Lasers; Limit of Detection; Neonicotinoids; Nitro Compounds; Oxazines; Pesticide Residues; Pyridines; Quantum Dots; Tellurium; Thiamethoxam; Thiazoles; Vegetables

Quantum dots (QDs) are fluorescent semiconductor nanoparticles with size-dependent emission spectra that can be excited by a broad choice of wavelengths. QDs have attracted a lot of interest for imaging, diagnostics, and therapy due to their bright, stable fluorescence. QDs can be conjugated to a variety of bio-active molecules for binding to bacteria and mammalian cells. QDs are also being widely investigated as cytotoxic agents for targeted killing of bacteria. The emergence of multiply-resistant bacterial strains is rapidly becoming a public health crisis, particularly in the case of Gram negative pathogens. Because of the well-known antimicrobial effect of certain nanomaterials, especially Ag, there are hundreds of studies examining the toxicity of nanoparticles to bacteria. Bacterial studies have been performed with other types of semiconductor nanoparticles as well, especially TiO(2), but also ZnO and others including CuO. Some comparisons of bacterial strains have been performed in these studies, usually comparing a Gram negative strain with a Gram positive. With all of these particles, mechanisms of toxicity are attributed to oxidation: either the photogeneration of reactive oxygen species (ROS) by the particles or the direct release of metal ions that can cause oxidative toxicity. Even with these materials, results of different studies vary greatly. In some studies the Gram positive test strain is reportedly more sensitive than the Gram negative; in others it is the opposite. These studies have been well reviewed. In all nanoparticle studies, particle composition, size, surface chemistry, sample aging/breakdown, and wavelength, power, and duration of light exposure can all dramatically affect the results. In addition, synthesis byproducts and solvents must be considered. High-throughput screening techniques are needed to be able to develop effective new nanomedicine agents. CdTe QDs have anti-microbial effects alone or in combination with antibiotics. In a previous study, we showed that coupling of antibiotics to CdTe can increase toxicity to bacteria but decrease toxicity to mammalian cells, due to decreased production of reactive oxygen species from the conjugates. Although it is unlikely that cadmium-containing compounds will be approved for use in humans, such preparations could be used for disinfection of surfaces or sterilization of water. In this protocol, we give a straightforward approach to solubilizing CdTe QDs with mercaptopropionic a

Topics: Anti-Bacterial Agents; Bacteria; Cadmium Compounds; Escherichia coli; Microbial Sensitivity Tests; Propionates; Quantum Dots; Solubility; Spectrophotometry, Ultraviolet; Tellurium

An automated technique for the identification, tracking and analysis of biological cells is presented. It is based on the use of nanoparticles, enclosed within intra-cellular vesicles, to produce clusters of discrete, point-like fluorescent, light sources within the cells. Computational analysis of these light ensembles in successive time frames of a movie sequence, using k-means clustering and particle tracking algorithms, provides robust and automated discrimination of live cells and their motion and a quantitative measure of their proliferation. This approach is a cytometric version of the moving light display technique which is widely used for analyzing the biological motion of humans and animals. We use the endocytosis of CdTe/ZnS, core-shell quantum dots to produce the light displays within an A549, epithelial, lung cancer cell line, using time-lapse imaging with frame acquisition every 5 minutes over a 40 hour time period. The nanoparticle moving light displays provide simultaneous collection of cell motility data, resolution of mitotic traversal dynamics and identification of familial relationships allowing construction of multi-parameter lineage trees.

Topics: Cadmium Compounds; Cell Line, Tumor; Cell Proliferation; Humans; Models, Theoretical; Nanoparticles; Nanotechnology; Quantum Dots; Sulfides; Tellurium; Zinc Compounds

In this paper, we prepared three types of transferrin-quantum dots conjugates (QDs-Tf) using three different methods (electrostatic interaction, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) coupling, denatured transferrin (dTf) coating). Fluorescence emission spectra, surface characteristics, zeta potentials of quantum dots (QDs) and QDs-Tf fluorescent probes were characterized by spectrophotometer, capillary electrophoresis, and dynamic light scattering. Fluorescent imaging of HeLa cells was also performed by QDs and QDs-Tf fluorescent probes. It was found that the fluorescence imaging performances of QDs-Tf probes prepared by electrostatic interaction and EDC coupling were better compared with the one prepared by dTf coating. Then a real-time single cell detection system was established to quantitatively evaluate cell labeling effects of QDs-Tf fluorescent probes. It was found that for cell labeling efficiency, the proportion of cells labeled by quantum dot probes to a group of cells, QDs-Tf probe prepared by EDC coupling showed the highest labeling efficiency (85.55±3.88%), followed by electrostatic interaction (78.86±9.57%), and dTf coating showed the lowest (40.09±10.2%). This efficiency order was confirmed by flow cytometry results. This study demonstrated the relationship between conjugation methods and the resultant QDs-Tf probes and provided a foundation for choosing appropriate QDs-Tf probes in cell labeling.

Topics: Cadmium Compounds; Flow Cytometry; Fluorescent Dyes; HeLa Cells; Humans; Molecular Imaging; Quantum Dots; Selenium Compounds; Spectrometry, Fluorescence; Staining and Labeling; Tellurium; Thioglycolates; Transferrin

Quantum dots (QDs) show promise as novel nanomaterials for sentinel lymph node (SLN) mapping through their use in noninvasive in vivo fluorescence imaging, and they have provided remarkable results. However, in vivo fluorescence imaging has limitations mainly reflected in the strong autofluorescence and low deepness of tissue penetration associated with this technique. Here, we report on the use of self-illuminating 3-mercaptopropionic acid-capped CdTe/CdS QDs for mouse axillary SLN mapping by bioluminescence resonance energy transfer, which was found to overcome these limitations [corrected]. We used CdTe/CdS QDs synthesized in aqueous solution to conjugate a mutant of the bioluminescent protein, Renilla reniformis luciferase. The nanobioconjugates obtained had an average hydrodynamic diameter of 19 nm, and their luminescence catalyzed by the substrate (coelenterazine) could penetrate into at least 20 mm of hairless pigskin, which could be observed using an in vivo imaging system equipped with a 700 nm emission filter. Conversely, the fluorescence of the nanobioconjugates penetrated no more than 10 mm of pigskin and was observed with a strong background. When 80 μL of the nanobioconjugates (containing about 0.5 μmol/L of QDs) and 5 μL of coelenterazine (1 μg/μL) were intradermally injected into a mouse paw, the axillary SLN could be imaged in real time without external excitation, and little background interference was detected. Furthermore, the decayed luminescence of QD-Luc8 in SLNs could be recovered after being intradermally reinjected with the coelenterazine. Our data showed that using self-illuminating QDs, as opposed to fluorescence QDs, has greatly enhanced sensitivity in SLN mapping, and that the SLN could be identified synchronously by the luminescence and fluorescence of the self-illuminating QDs.

Topics: 3-Mercaptopropionic Acid; Animals; Cadmium Compounds; Fluorescent Dyes; Injections, Intradermal; Luminescent Measurements; Lymph Nodes; Mice; Nanoconjugates; Optical Imaging; Quantum Dots; Sentinel Lymph Node Biopsy; Skin; Skin Absorption; Spectrometry, Fluorescence; Sulfides; Swine; Tellurium; Whole Body Imaging

BACKGROUND AND OBJECTIVE. Nanotechnology works with substances at a nanometer scale, and it offers many solutions for biomedicine. Nanoparticles (NPs) have been shown as effective agents for imaging, drug delivery, pathogen detection, etc. However, to date, NP toxicity is poorly known. The aim of our study was to investigate the embryotoxicity and teratogenicity of quantum dots (QDs) at the different stages of rat embryogenesis. MATERIALS AND METHODS. Wistar rats were injected with CdSe/ZnS or CdTe QDs on the 6th, 13th, and 18th days of embryogenesis. Cyclophosphamide was chosen as a positive control of embryotoxicity. On the 21st day, the number of resorptions, weight, length, and external malformations of the embryos were estimated. Fluorescence spectroscopy and microscopy analysis were used to determine the accumulation of QDs in the tissues. RESULTS. Exposure to cyclophosphamide during the pregnancy decreased the embryonic weight and length when compared with the control group and produced numerous malformations. The effects depended on the stage of embryogenesis. Meanwhile, QDs did not cause any embryotoxic or teratogenic effects. However, CdTe QDs induced necrosis in the tissues of the peritoneal cavity. The necrotic tissues contained QDs with altered spectroscopic properties. Spectroscopic and microscopic tissue examination revealed that QDs accumulated in the placenta, but no penetration to the embryonic tissues was observed. CONCLUSIONS. QDs did not cause any direct embryotoxic or teratogenic effects, but they had adverse effects on the maternal organism. The observed QD effects and the long-term accumulation of QDs in the maternal organism may increase the risk of adverse effects on embryo development.

Topics: Abnormalities, Drug-Induced; Animals; Cadmium Compounds; Cyclophosphamide; Embryo, Mammalian; Embryonic Development; Female; Nanoparticles; Pregnancy; Quantum Dots; Rats; Selenium Compounds; Sulfides; Tellurium; Zinc Compounds

The typical reaction of spironaphthoxazine is the conversion between the non-polar spiro form and polar merocyanine form. Quantum dots (QDs) have unique optical properties and several advantages over conventional organic dyes. In this work, the CdTe QDs containing a water-soluble spironaphthoxazine was used as the optical probe photoisomerization between spiro and merocyanine. The initial bright fluorescence of CdTe QDs was effectively quenched by water-soluble spironaphthoxazine using UV irradiation. Reversible modulation of fluorescence intensity of CdTe QDs was achieved using alternating irradiation with UV and visible light. The possible mechanism is discussed.

Topics: Absorption; Cadmium Compounds; Luminescence; Oxazines; Quantum Dots; Solubility; Spectrometry, Fluorescence; Spiro Compounds; Tellurium; Temperature; Ultraviolet Rays; Water

CdTe/CdSe core/shell nanocrystals are the prototypical example of type-II nanoheterostructures, in which the electron and the hole wave functions are localized in different parts of the nanostructure. As the thickness of the CdSe shell increases above a few monolayers, the spectroscopic properties of such nanocrystals change dramatically, reflecting the underlying type-I → type-II transition. For example, the exciton Stokes shift and radiative lifetime increase, while the decreasing biexciton binding energy changes sign from positive to negative. Recent experimental results for CdSe nanocrystals isoelectronically doped with a few Te substitutional impurities, however, have revealed a very different dependence of the optical and electronic properties on the nanocrystal size. Here we use atomistic calculations based on the pseudopotential method for single-particle excitations and the configuration-interaction approach for many-particle excitations to investigate carrier localization and electronic properties of CdTe/CdSe nanocrystals as the size of the CdTe core decreases from a few nm (characteristic of core/shell CdTe/CdSe nanocrystals) to the single impurity limit. We find that the unusual spectroscopic properties of isoelectronically doped CdSe:Te nanocrystals can be rationalized in terms of the change in the localization volume of the electron and hole wave functions as the size of the nanocrystal increases. The size dependence of the exciton Stokes shift, exciton radiative lifetime, and biexciton binding energy reflects the extent of carrier localization around the Te impurities.

Topics: Cadmium Compounds; Computer Simulation; Electron Transport; Light; Models, Chemical; Models, Molecular; Nanostructures; Particle Size; Scattering, Radiation; Selenium Compounds; Tellurium

Temperature and photo-responsive aqueous CdTe quantum dots (QDs)/spironaphthoxazine (WSPO)/poly(N-isopropylacrylamide) (PNIPAM) hybrid was studied in this paper. Phase transition and fluorescent decrease were observed in aqueous QDs/WSPO/PNIPAM hybrid by rising temperature, and color and fluorescent switching were also observed upon irradiation of UV/Vis light.

Topics: Absorption; Acrylamides; Acrylic Resins; Benzopyrans; Cadmium Compounds; Indoles; Light; Oxazines; Polymers; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spiro Compounds; Tellurium; Temperature; Water

An aqueous synthesis method to obtain highly luminescent cadmium telluride nanocrystals is described. We have shown water-soluble semi-conductor quantum dots with high photoluminescence quantum yield have great potential for biological applications. The spectral properties of these nanocrystals can be easily tuned according to their particle size to yield multicolours simultaneously by a single excitation light source. A stable precursor material sodium tellurite is utilised instead of the traditional oxygen sensitive NaHTe or H2Te as Te source. We have introduced mercaptosuccinic acid and propylisobutyl polyhedral oligomeric silsesquioxane nanoparticles as novel capping agents to stabilize the nanocrystals, synthesized in borate-citrate buffering system. Inclusion of propylisobutyl polyhedral oligomeric silsesquioxane nanoparticles in the capping procedure showed enhanced stability and biocompatibility. The presence of mercaptosuccinic acid/propylisobutyl polyhedral oligomeric silsesquioxane coatings was confirmed by Fourier Transform Infrared spectroscopy and average sizes of 2-5 nm by transmission electron microscopy measurements. The functionalized and targeted quantum dots detected cancer cell death on exposure to some anticancer drugs. Studies have indicated that apoptotic cells can activate signaling pathways in dendritic cells via ligation of surface receptors. Cells treated with specific class of pro-apototic drug such as anthracyclines mount an anti-tumour immune response when introduced into mice. Apoptotic cells may be immunogenic or non-immunogenic depending on the presence of calreticulin on the plasma membrane of dying tumour cells. Here the confocal microscopy showed localization of conjugated mercaptosuccinic acid/propylisobutyl polyhedral oligomeric silsesquioxane cadmium telluride quantum dots on MCF-7 cells when exposed to cadmium ions at 50 microM, compared to coated quantum dots. We have used cadmium ions as a model drug as certain anticancer drugs (anthracyclines) induce translocation of calreticulin to the cell membrane, an indicator of apoptosis. Antibodies generated against a peptide to human calreticulin and conjugated to quantum dots detected the protein on cell membrane of stimulated cells were visualized by confocal microscopy. Stimulating natural immune response, against tumours has enormous potential to improve current regimens of cancer detection and therapy.

Topics: Breast Neoplasms; Cadmium Compounds; Cell Line, Tumor; Humans; Microscopy, Fluorescence; Nanocapsules; Organosilicon Compounds; Quantum Dots; Staining and Labeling; Tellurium; Thiomalates

Sugar chains are important molecules in cellular recognition and signaling, and quantum dots (QDs) are a very powerful tool for in vitro and in vivo imaging. Herein, we report the preparation of stable sugar-chain-immobilized fluorescent nanoparticles (SFNPs) and their application to the analysis of sugar-chain-protein interactions and cellular imaging. SFNPs were easily prepared by mixing CdTe/CdS core/shell QDs with our previously developed sugar-chain-ligand conjugates. The obtained SFNPs were very stable and could be stored for several months. In the binding analysis, β-galactose- and α-glucose-immobilized SFNPs were specifically interacted with Ricinus communis agglutinin I and concanavalin A, respectively, and made into aggregates. The binding interaction was detected visually, fluorescently, or both. In the experiment for cellular imaging, it was found that SFNPs were predominantly taken up by human hepatocyto carcinoma cells (HepG2), suggesting the possible usage of our designed SFNPs for various biochemical analyses of sugar chains.

Topics: Cadmium Compounds; Concanavalin A; Galactose; Glucose; Hep G2 Cells; Humans; Microscopy, Confocal; Plant Lectins; Protein Binding; Quantum Dots; Selenium Compounds; Tellurium

Quantum dots (QDs) are fluorescent semiconductor nanocrystals that have the potential for major advancements in the field of nanomedicine through their unique photophysical properties. They can potentially be used as fluorescent probes for various biomedical imaging applications, including cancer localization, detection of micrometastasis, image guided surgery, and targeted drug delivery. Their main limitation is toxicity, which requires a biologically compatible surface coating to shield the toxic core from the surrounding environment. However, this leads to an increase in QD size that may lead to problems of excretion and systemic sequestration. We describe a one pot synthesis, characterization, and in vitro cytotoxicity of a novel polyhedral oligomeric silsesquioxane (POSS)-coated CdTe-cored QD using mercaptosuccinic acid (MSA) and D-cysteine as stabilizing agents. Characterization was performed using transmission electron microscopy Fourier transform infrared spectroscopy, and photoluminescence studies. POSS-coated QDs demonstrated high colloidal stability and enhanced photostability on high degrees of ultraviolet (UV) excitation compared to QDs coated with MSA and D-cysteine alone (P value < 0.05). In vitro toxicity studies showed that both POSS and MSA-QDs were significantly less toxic than ionized salts of Cd(+2) and Te(-2). Confocal microscopy confirmed high brightness of POSS-QDs in cells at both 1 and 24 hours, indicating that these QDs are rapidly taken up by cells and remain photostable in a biological environment. We therefore conclude that a POSS coating confers biological compatibility, photostability, and colloidal stability while retaining the small size and unique photophysical properties of the QDs. The amphiphilic nature of the coating allows solubility in aqueous solutions and rapid transfer across cell membranes, enabling the use of lower concentrations of the QDs for an overall reduced toxicity particularly for prolonged live cell and in vivo imaging applications.

Topics: Analysis of Variance; Cadmium Compounds; Cell Shape; Cell Survival; Cysteine; Hep G2 Cells; Humans; Microscopy, Confocal; Organosilicon Compounds; Quantum Dots; Solubility; Spectroscopy, Fourier Transform Infrared; Surface Properties; Tellurium; Thiomalates; Ultraviolet Rays

Aqueous quantum dots (QDs) directly synthesized with various thiol ligands have been investigated as imaging probes in living cells. However, the effect of the surface chemistry of these ligands on QDs' cellular uptakes and their intracellular fate remains poorly understood. In this work, four CdTe QDs were directly synthesized under aqueous conditions using four different thiols as stabilizers and their interactions with cells were investigated. Fluorescence correlation spectroscopy (FCS), X-ray photoelectron spectroscopy (XPS), and zeta potential measurements on QDs primarily show that the surface structure of these QDs is highly dependent on the thiol ligands used in the preparation of QDs' precursors, including its layer thicknesses, densities, and surface charges. Subsequently, FCS integrated with the maximum-entropy-method-based FCS (MEMFCS) was used to investigate the concentration distribution and dynamics of these QDs in living A-427 cells. Our findings indicate that QDs' surface characteristics affect cell membrane adsorption and subsequent internalization. More critically, we show that the cellular uptake of aqueous QDs is dependent on their hydrodynamic diameter and might have the potential to escape trapped environments to accumulate in the cytoplasm.

Topics: Cadmium Compounds; Cells, Cultured; Fluorescent Dyes; Humans; Hydrodynamics; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium; Water

The analyte-induced formation of exciton trapping leads to the decrease of cathode photocurrent of mercapto-capped CdTe quantum dots (QDs), which produces a sensitive cathode photoelectrochemical method for selective sensing of trace Cu(2+) as the analyte with a linear range from 0.06 to 100 μM.

Topics: Cadmium Compounds; Copper; Electrochemical Techniques; Electrodes; Photochemical Processes; Quantum Dots; Tellurium

Chemically denatured ovalbumin (dOB) was used to modify the surface of 3-mercaptopropionic acid (MPA) stabilized CdTe quantum dots (QDs), which resulted in a great enhancement of the synchronous fluorescence intensity. Moreover, dOB shell layer can effectively prevent the binding of other cations onto the QDs core and enhance the selective binding ability of Hg(2+) to dOB coated CdTe QDs (CdTe-dOB QDs). A simple method with high sensitivity and selectivity was developed for the determination of Hg(2+) with the CdTe-dOB QDs as fluorescence probe based on the merits of synchronous fluorescence spectroscopy (SFS). When scanning with excitation and emission wavelengths of 250 nm and 470 nm (Δλ=λ(em)-λ(ex)=220 nm), respectively, the maximum synchronous fluorescence peak of the CdTe-dOB QDs was located at 328 nm. Under optimal conditions, the change of the synchronous fluorescence intensity was in good linear relationship with the Hg(2+) concentration in the range of 0.08×10(-7) to 30.0×10(-7) mol L(-1) and the detection limit was 4.2×10(-9) mol L(-1) (S/N=3). The relative standard deviation of seven replicate measurements for the concentration of 2.0×10(-7) mol L(-1) and 20.0×10(-7) mol L(-1) were 2.8% and 2.3%, respectively. Compared with general fluorescence methods, the proposed method, which combined the advantages of high sensitivity of synchronous fluorescence and specific response of Hg(2+) to CdTe-dOB, had a wider linear range and higher sensitivity. Furthermore, the proposed method was applied to the determination of trace Hg(2+) in water samples with satisfactory results.

Topics: Cadmium Compounds; Fluorescent Dyes; Hydrogen-Ion Concentration; Mercury; Ovalbumin; Protein Denaturation; Quantum Dots; Spectrometry, Fluorescence; Tellurium; Water

A highly sensitive electrochemiluminescence (ECL) immunosensor for the detection of prostate specific antigen (PSA) was designed using biofunctionalized magnetic graphene nanosheets (G@Fe(3)O(4)) as immunosensing probes and CdTe quantum dots coated silica nanospheres (Si/QDs) as signal amplification labels. In this work, a sandwich-type immunosensor was fabricated, which was assembled on the surface of indium tin oxide glass (ITO). The analyte was detected in a home-made flow injection ECL (FI-ECL) cell through the immunosensor. Owing to the signal amplification of G@Fe(3)O(4) composite and Si/QDs, the ECL measurement showed a great increase in detection signals compared with the unamplified method. Under optimal conditions, a wide detection range (0.003-50 ng mL(-1)) and a low detection limit (0.72 pg mL(-1)) were obtained through the sandwich-type immunosensor. The proposed strategy successfully demonstrated a reproducible, specific, and potent method that can be expanded to detect other proteins.

Topics: Biomarkers, Tumor; Cadmium Compounds; Electrochemistry; Electron Transport; Graphite; Humans; Immunoassay; Luminescent Measurements; Magnetite Nanoparticles; Models, Molecular; Molecular Conformation; Prostate-Specific Antigen; Quantum Dots; Silicon Dioxide; Staining and Labeling; Tellurium

We report a conjugate of thioglycolic acid (TGA) capped CdTe quantum dot and Eu(3+) ion (TGA-CdTe QD-Eu(3+)) that can be used as an ultrasensitive luminescence turn-on sensor for nucleoside triphosphates (NTPs). The TGA-CdTe QD-Eu(3+) conjugate is a weakly luminescent species as a result of the strong quenching effect of Eu(3+) ion on the luminescence of TGA-CdTe QDs. The conjugate's luminescence can be readily restored by its reaction with adenosine triphosphate (ATP) and other NTPs, and thus gives an ultrasensitive detection of NTPs, with a detection limit of 2 nM. The sensing mechanism has also been explored, and the effective quenching of TGA-CdTe QDs emission by Eu(3+) ions has been attributed to photoinduced electron transfer (PET). ATP, as the representative of NTPs, can remove Eu(3+) from the surface of TGA-CdTe QDs, leading to restoration of the TGA-CdTe QDs luminescence.

Topics: Adenosine Triphosphate; Cadmium Compounds; Chemistry Techniques, Analytical; Electron Transport; Europium; Luminescent Measurements; Nucleotides; Quantum Dots; Tellurium; Thioglycolates

In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1-30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography.

Topics: Cadmium Compounds; Computer Simulation; Mammography; Signal Processing, Computer-Assisted; Spectrum Analysis; Tellurium; X-Rays

Monodisperse CdTe composite microspheres with a spherical shape were prepared using organosilane chemicals in aqueous solution. CdTe nanocrystals (NCs) were loaded into the matrix of silica microspheres during the formation of composite microspheres. Detailed characterization of the CdTe composite microspheres by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and spectrofluorimeter was performed to elucidate the morphology and fluorescence of the composite microspheres. In contrast to CdTe NCs in aqueous solution, CdTe NCs in the composite microspheres revealed high stability and fluorescence due to the confined effects of silica matrix. In addition, multicolored CdTe QDs were encoded into the microspheres at precise ratios.

Topics: Cadmium Compounds; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Microspheres; Nanoparticles; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

Spectroscopic x-ray imaging by means of photon counting detectors has received growing interest during the past years. Critical to the image quality of such devices is their pixel pitch and the sensor material employed. This paper describes the imaging properties of Medipix2 MXR multi-chip assemblies bump bonded to 1 mm thick CdTe sensors. Two systems were investigated with pixel pitches of 110 and 165 μm, which are in the order of the mean free path lengths of the characteristic x-rays produced in their sensors. Peak widths were found to be almost constant across the energy range of 10 to 60 keV, with values of 2.3 and 2.2 keV (FWHM) for the two pixel pitches. The average number of pixels responding to a single incoming photon are about 1.85 and 1.45 at 60 keV, amounting to detective quantum efficiencies of 0.77 and 0.84 at a spatial frequency of zero. Energy selective CT acquisitions are presented, and the two pixel pitches' abilities to discriminate between iodine and gadolinium contrast agents are examined. It is shown that the choice of the pixel pitch translates into a minimum contrast agent concentration for which material discrimination is still possible. We finally investigate saturation effects at high x-ray fluxes and conclude with the finding that higher maximum count rates come at the cost of a reduced energy resolution.

Topics: Cadmium Compounds; Contrast Media; Image Processing, Computer-Assisted; Phantoms, Imaging; Radiometry; Tellurium; Temperature; Tomography, X-Ray Computed; Water

Quantum Dots have shown remarkable potentials in biomedical research. Herein, we reported the effects of CdTe quantum dots (QDs) and CdTe@SiO2 nanoparticles (NPs) on human embryonic kidney 293 (HEK 293A) cells with the aim of investigating their in vitro cytotoxicity. The CdTe@SiO2 particles were prepared by reverse microemulsion method. The structural morphology of the CdTe and hydrophilic silica-coated CdTe particles were characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectrometry and photoluminescence (PL) spectrometry. The in vitro cytotoxicity of CdTe QDs and CdTe@SiO2 nanoparticles was assessed in 293A cells using standard MTT assay, western blot and fluorescent microscopy. The results showed that the CdTe and CdTe@SiO2 particles were relatively uniform with the diameter of about 3.8 nm, 75 nm respectively. The cell viability and the adhesion ability were similar to the control 293A cells. The level of the fibronectin protein expression was decreased with the increasing concentration of CdTe while the no effects were observed on expression of beta-actin in CdTe as well as CdTe@SiO2 treated cells even at highest concentration of 45 microg/mL which demonstrated their good biocompatibility to 293A cells. The results indicate that the CdTe@SiO2 nanoparticles are attractive candidates for biological imaging studies as expected.

Topics: Cadmium Compounds; Cell Line; Humans; Microscopy, Electron, Transmission; Nanoparticles; Quantum Dots; Silicon Dioxide; Tellurium

The assembly and isolation of DNA oligonucleotide-functionalized gold nanoparticles (AuNPs) has become a well-developed technology that is based on the strong bonding interactions between gold and thiolated DNA. However, achieving DNA-functionalized semiconductor quantum dots (QDs) that are robust enough to withstand precipitation at high temperature and ionic strength through simple attachment of modified DNA to the QD surface remains a challenge. We report the synthesis of stable core/shell (1-20 monolayers) QD-DNA conjugates in which the end of the phosphorothiolated oligonucleotide (5-10 nucleotides) is "embedded" within the shell of the QD. These reliable QD-DNA conjugates exhibit excellent chemical and photonic stability, colloidal stability over a wide pH range (4-12) and at high salt concentrations (>100 mM Na(+) or Mg(2+)), bright fluorescence emission with quantum yields of up to 70%, and broad spectral tunability with emission ranging from the UV to the NIR (360-800 nm).

Topics: Cadmium Compounds; DNA; Fluorescence; Gold; Infrared Rays; Metal Nanoparticles; Quantum Dots; Semiconductors; Sulfides; Tellurium; Ultraviolet Rays

This work reports a novel nanobiosensor based on a thioglycolic acid (TGA)-capped CdTe quantum dot-laccase (Lac) enzyme system for sensitive detection of dopamine (DA). The enzyme used catalyzes the oxidation of DA to dopamine-o-quinone (DOQ), which can selectively quench the strong luminescence of CdTe nanocrystals at neutral pH. The relationship between luminescence intensity of CdTe nanocrystals and DA concentration is nicely described by the Stern-Volmer equation. At an optimum pH of 7.4, the proposed sensor gives a linear calibration over a DA concentration range of 0.3 to 100 μM, with a limit of detection of 0.16 μM and a response time of 2 min. The relative standard deviation for seven replicate determinations of 6.0 μM of DA was found to be 3.7%. The sensor was successfully applied to the determination of DA in a blood plasma sample and in a DA injection formulation.

Topics: Biosensing Techniques; Cadmium Compounds; Dopamine; Laccase; Quantum Dots; Tellurium

Mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs) with particle size 3 nm have been successfully synthesized in aqueous medium by hydrothermal synthesis method. And the effects of different metal ions on MPA capped CdTe QDs fluorescence were studied using fluorescence spectrometry. The results demonstrated that at the same concentration level, Ag(+) could strongly quench CdTe QDs fluorescence, and the other metal ions had little effect on CdTe QDs fluorescence except Cu(2+). On the basis of this fact, a rapid, simple, highly sensitive and selective method based on fluorescence quenching principle for Ag(+) detection in aqueous solution was proposed. Under optimal conditions, the quenched fluorescence intensity (F(0)-F) increased linearly with the concentration of Ag(+) ranging from 4 × 10(-7) to 32 × 10(-7)mol L(-1). The limit of detection for Ag(+) was 4.106 × 10(-8)mol L(-1). The obtained plot of F(0)/F versus [Ag(+)] was an upward curvature, concave towards the y-axis, rather than a straight line. The modified form of the Stern-Volmer equation was third order in Ag(+) concentration. According to the modified Stern-Volmer equation, it can be inferred that dynamic quenching and static quenching simultaneously occurred when Ag(+) interacted with MPA capped CdTe QDs. At the same time other factors might also influence the quenching process. Based on this study, hydrothermal synthesized MPA capped CdTe QDs with particle size 3 nm may be used as a novel fluorescence probe to quantificationally and selectively detect Ag(+).

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Cations, Monovalent; Fluorescent Dyes; Limit of Detection; Particle Size; Quantum Dots; Silver; Spectrometry, Fluorescence; Tellurium

Droplet methods have been successfully applied in DNA hybridization analysis and protein-protein interaction. Existing assay methods implemented in droplet platforms are severely limited by expensive and high-maintenance equipment. As a convenient detection method, colorimetry provides a new path for microscale assay since it can enhance assay efficiency and simplify the detection procedure. Here, a microscale immunoassay for α-fetoprotein (AFP) was developed for the first time by the incorporation of colorimetry and droplet platform. Ru(bpy)(2)(mcbpy-O-Su-ester)(PF(6))(2) complex (Ru) was coupled with the monoclonal antibody (Ab) of AFP to form a stable red Ru-Ab complex both as a quencher for green CdTe quantum dots (QDs) and as a capture probe for AFP. In the absence of AFP, the mixed droplet showed a red color. With the increase of AFP concentration, the color change of the droplet was from red to green as a result of the competition of AFP with QDs for Ru-Ab. The biosensor exhibited not only good sensitivity and specificity for AFP with a detection limit of 0.06 ng ml(-1), but also satisfactory performance in diluted human sera with a detection limit of 0.4 ng ml(-1). Notably, a visual droplet platform for screening cancer biomarkers by the naked eye based on this principle is anticipated.

Topics: alpha-Fetoproteins; Biosensing Techniques; Cadmium Compounds; Colorimetry; Coordination Complexes; Immunoassay; Limit of Detection; Quantum Dots; Ruthenium; Spectrometry, Fluorescence; Tellurium

Colloidal CdTe quantum wires are reported having ensemble photoluminescence efficiencies as high as 25% under low excitation-power densities. High photoluminescence efficiencies are achieved by formation of a monolayer CdS shell on the CdTe quantum wires. Like other semiconductor nanowires, the CdTe quantum wires may contain frequent wurtzite-zinc-blende structural alternations along their lengths. The present results demonstrate that the optical properties, emission-peak shape and photoluminescence efficiencies, are independent of the presence or absence of such structural alternations.

Topics: Cadmium Compounds; Colloids; Quantum Dots; Semiconductors; Sulfides; Tellurium

We have designed a series of short RGD peptide ligands and developed one-pot aqueous synthesis of integrin-binding CdTe and CdZnTe quantum dots (QDs). We first examined the effects of different RGD peptides, including RGDS, CRGDS, Ac-CRGDS, CRGDS-CONH₂, Ac-CRGDS-CONH₂, RGDSC, CCRGDS, and CCCRGDS, on the synthesis of CdTe QDs. CRGDS were found to be the optimal ligand, providing the CdTe QDs with well-defined wavelength ranges (500-650 nm) and relatively high photoluminescence quantum yields (up to 15%). The key synthesis parameters (the pH value of the Cd²⁺-RGD precursors and the molar ratio of RGD/Cd²⁺) were assessed. In order to further improve the optical properties of the RGD-capped QDs, zinc was then incorporated by the simultaneous reaction of Cd²⁺ and Zn²⁺ with NaHTe. By using a mixture of CRGDS and cysteine as the stabilizer, the quantum yields of CdZnTe alloy QDs reached as high as 60% without any post-treatment, and they also showed excellent stability against time, pH, and salinity. Note that these properties could not be obtained with CRGDS or cysteine alone as the stabilizer. Finally, we demonstrated that the RGD-capped QDs preferentially bind to cell surfaces because of the specific recognition of the RGD sequence to cell surface integrin receptors. Our synthesis strategy based on RGD peptides thus represents a convenient route for opening up QD technologies for cell-specific tagging and labeling applicable to a wide range of diagnostics and therapy.

Topics: Cadmium Compounds; Crystallization; HeLa Cells; HL-60 Cells; Humans; Integrins; Materials Testing; Microscopy, Fluorescence; Oligopeptides; Quantum Dots; Subcellular Fractions; Tellurium; Zinc

A novel fluorescence immunoassay method for fast and ultrasensitive detection of avian influenza virus (AIV) was developed. The immunoassay method which integrated lateral flow test strip technique with fluorescence immunoassay used the label-free and high luminescent quantum dots (QDs) as signal output. By the sandwich immunoreaction performed on lateral flow test strip, the gold nanoparticle (NP) labels were captured in the test zone and further dissolved to release a large number of gold ions as a signal transduction bridge that was detected by the QDs-based fluorescence quenching method. Under the optimal conditions, the relative fluorescence intensity of QDs was linear over the range of 0.27-12 ng mL(-1) AIV, and the limit of detection was estimated to be 0.09 ng mL(-1) which was 100-fold greater than enzyme-linked immunosorbent assay (ELISA). The sensitive and specific response was also coupled with high reproducibility in the proposed method. A series of six parallel measurements produced reproducible fluorescent signals with a relative standard deviation of 4.7%. The proposed method can be used to directly detect clinical sample without any pretreatment, and showed high efficiency (90.0%), sensitivity (100.0%) and specificity (88.2%) compared with virus isolation (gold method). The new method shows great promise for rapid, sensitive, and quantitative detection of AIV in-field or point-of-care diagnosis.

Topics: Animals; Antibodies, Viral; Cadmium Compounds; Chickens; Cost-Benefit Analysis; Fluorescent Dyes; Gold; Immunoassay; Influenza A virus; Influenza in Birds; Metal Nanoparticles; Point-of-Care Systems; Quantum Dots; Reagent Strips; Spectrometry, Fluorescence; Tellurium; Time Factors

The synthesis of water-soluble quantum dots (QDs) in aqueous phase has received much attention recently. To date various kinds of QDs such as CdTe, CdSe, CdTe/CdS and CdSe/ZnS have been synthesized by aqueous methods. However, generally poor-quality QDs (photoluminescent quantum yield (PLQY) lower than 30%) are obtained via this method and the 3-mercaptopropionic acid stabilizer is notorious for its toxicity and awful odor. Here we introduce a novel thiol ligand, N-acetyl-L-cysteine, as an ideal stabilizer that is successfully employed to synthesize high-quality CdTe/CdS/ZnS QDs via a simple aqueous phase. The core/shell/shell structures of the CdTe/CdS/ZnS QDs were verified by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, x-ray powder diffraction and transmission electron microscopy. These QDs not only possess a high PLQY but also have excellent photostability and favorable biocompatibility, which is vital for many biological applications. This type of water-dispersed QD is a promising candidate for fluorescent probes in biological and medical fields.

Topics: Biocompatible Materials; Cadmium Compounds; Crystallization; Fluorescent Dyes; Materials Testing; Phase Transition; Quantum Dots; Selenium Compounds; Tellurium; Water; Zinc Compounds

The vast application of fluorescent semiconductor nanoparticles (NPs) or quantum dots (QDs) has prompted the development of new, cheap and safer methods that allow generating QDs with improved biocompatibility. In this context, green or biological QDs production represents a still unexplored area. This work reports the intracellular CdTe QDs biosynthesis in bacteria. Escherichia coli overexpressing the gshA gene, involved in glutathione (GSH) biosynthesis, was used to produce CdTe QDs. Cells exhibited higher reduced thiols, GSH and Cd/Te contents that allow generating fluorescent intracellular NP-like structures when exposed to CdCl(2) and K(2)TeO(3). Fluorescence microscopy revealed that QDs-producing cells accumulate defined structures of various colors, suggesting the production of differently-sized NPs. Purified fluorescent NPs exhibited structural and spectroscopic properties characteristic of CdTe QDs, as size and absorption/emission spectra. Elemental analysis confirmed that biosynthesized QDs were formed by Cd and Te with Cd/Te ratios expected for CdTe QDs. Finally, fluorescent properties of QDs-producing cells, such as color and intensity, were improved by temperature control and the use of reducing buffers.

Topics: Cadmium Compounds; Citrates; Escherichia coli; Genes, Bacterial; Glutathione; Microscopy, Fluorescence; Nanoparticles; Particle Size; Quantum Dots; Spectrometry, Fluorescence; Spectroscopy, Fourier Transform Infrared; Tellurium; Temperature; X-Ray Diffraction

High-quality cysteamine-coated CdTe quantum dots (CA-CdTe QDs) were successfully synthesized in aqueous phase by a facile one-pot method. Through hydroxylamine hydrochloride-promoted kinetic growth strategy, water-soluble CA-CdTe QDs could be obtained conveniently in a conical flask by a stepwise addition of raw materials. The photoluminescence quantum yield (PL QY) of the obtained QDs reached 9.2% at the emission peak of 520nm. The optical property and the morphology of the QDs were characterized by UV-vis absorption spectra, photoluminescence spectra (PL) and transmission electron microscopy (TEM) respectively. Furthermore, the fluorescence of the resultant QDs was quenched by copper (II) (Cu(2+)) and mercury (II) (Hg(2+)) meanwhile. It is worthy of note that to separately detect Hg(2+), cyanide ion could be used to eliminate the interference of Cu(2+). Under the optimal conditions, the response was linearly proportional to the logarithm of Hg(2+) concentration over the range of 0.08-3.33μM with a limit of detection (LOD) of 0.07μM.

Topics: Cadmium Compounds; Copper; Cyanides; Cysteamine; Ions; Mercury; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium

Bovine serum albumin (BSA)-coated CdTe/ZnS quantum dots (BSA-QDs) were selected to conjugate with folic acid (FA), forming FA-BSA-QDs. This study aims to develop these small FA-BSA-QDs (less than 10 nm) for the diagnosis of cancers in which the FA receptor (FR) is overexpressed. The enhancement of cellular uptake in FR-positive human nasopharyngeal carcinoma cells (KB cells) for FA-BSA-QDs was found by means of confocal fluorescence microscopy under single-photon and two-photon excitation. The uptake enhancement for FA-BSA-QDs was further evaluated by flow-cytometric analysis in 10(4) KB cells, and was about 3 times higher than for BSA-QDs on average. The uptake enhancement was suppressed when KB cells had been pretreated with excess FA, reflecting that the enhancement was mediated by the association of FR at cell membranes with FA-BSA-QDs. When human embryonic kidney cells (293T) (FR-negative cells) and KB cells, respectively, were incubated with FA-BSA-QDs (1 μM) for 40 min, the FA-BSA-QD uptake by 293T cells was much weaker than that by KB cells, demonstrating that FA-BSA-QDs could undergo preferential binding on FR-positive cancer cells. These characteristics suggest that FA-BSA-QDs are potential candidates for cancer diagnosis.

Topics: Animals; Antineoplastic Agents; Cadmium Compounds; Carcinoma; Cattle; Cell Survival; Cells, Cultured; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Folic Acid; Humans; Microscopy, Confocal; Molecular Imaging; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Particle Size; Photons; Quantum Dots; Serum Albumin, Bovine; Structure-Activity Relationship; Sulfides; Surface Properties; Tellurium; Zinc Compounds

Luminescent near-infrared (NIR) CdTe/CdSe QDs were synthesized and encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanospheres to prepare stable and biocompatible QDs-loaded nanospheres for in vivo imaging. QDs were encapsulated with PLGA nanospheres by a solid dispersion method and optimized to have high fluorescence intensity for in vivo imaging detection. The resultant QDs-loaded PLGA nanospheres were characterized by various analytical techniques such as UV-Vis measurement, dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM). Finally, we evaluated toxicity and body distribution of QDs loaded in PLGA nanospheres in vitro and in vivo, respectively. From the results, the QDs loaded in PLGA nanospheres were spherical and showed a diameter range of 135.0-162.3 nm in size. The QD nanospheres increased their stability against photooxidation and photobleaching, which have the high potential for applications in biomedical imaging. We have also attained non-invasive in vivo imaging with light photons, representing an intriguing avenue for obtaining biological information by the use of NIR light.

Topics: Animals; Cadmium Compounds; Cell Line, Tumor; Cell Survival; Humans; Lactic Acid; Luminescent Measurements; Mice; Nanospheres; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Quantum Dots; Selenium Compounds; Spectroscopy, Near-Infrared; Tellurium; Whole Body Imaging

Although CdTe nanocrystal has been applied in quantum dot (QD)-based solar cells, there is no report on a graphene-CdTe QD hybrid system and its photoresponses. In this work, graphene-CdTe QD composed nanosheets were one-step synthesized in aqueous solution using a hydrothermal method and demonstrated enhanced photoresponses, rendering potentials in optoelectronics applications. This work could provide an environmental-friendly and universal approach to fabricate graphene-based hybrid nanomaterials for various applications.

Topics: Cadmium Compounds; Graphite; Nanostructures; Nanotechnology; Photochemistry; Quantum Dots; Tellurium

Here we report a facile switchable fluorescent QD probe for F(-) ions, which is based on the hydrogen bonding-driven aggregation and the analyte-triggered disaggregation.

Topics: Cadmium Compounds; Cysteamine; Fluorescent Dyes; Hydrogen Bonding; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Herein, we present a novel label-free fluorescent assay for monitoring the activity and inhibition of protein kinases based on the aggregation behavior of unmodified CdTe quantum dots (QDs). In this assay, cationic substrate peptides induce the selective aggregation of unmodified QDs with anionic surface charge, whereas phosphorylated peptides do not. Phosphorylation by kinase alters the net charge of peptides and subsequently inhibits the aggregation of unmodified QDs, causing an enhanced fluorescence with a 45 nm blue-shift in emission and a yellow-to-green emission color change. Hence the fluorescence response allows this QD-based method to easily probe kinase activity by a spectrometer or even by the naked eye. The feasibility of the method has been demonstrated by sensitive measurement of the activity of cAMP-dependent protein kinase (PKA) with a low detection limit (0.47 mU μL(-1)). On the basis of the fluorescence response of QDs on the concentration of PKA inhibitor H-89, the IC(50) value, the half maximal inhibitory concentration, was estimated, which was in agreement with the literature value. Moreover, the system can be applicable to detect the Forskolin/3-isobutyl-1-methylxantine (IBMX)-stimulated activation of PKA in cell lysate. Unlike the existing QD-based enzyme activity assays in which the modification process of QDs is essential, this method relies on unmodified QDs without the requirement of peptide labeling and QDs' modification, presenting a promising candidate for cost-effective kinase activity and inhibitor screening assays.

Topics: Amino Acid Sequence; Cadmium Compounds; Cell Extracts; Cell Line, Tumor; Cyclic AMP-Dependent Protein Kinases; Enzyme Activation; Enzyme Assays; Fluorescent Dyes; Humans; Peptides; Protein Kinase Inhibitors; Protein Kinases; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium

Multiple CdTe quantum dots (QDs) were incorporated in SiO(2) beads using a reverse micelle route (i.e., a water-in-oil emulsion) and a precursor solution of SiO(2)-coated CdTe QDs as the water phase. The QDs in the beads retained their initial photoluminescence efficiency (56%) because they had a thin SiO(2) shell that prevented removal of the ligands from their surface during incorporation. Because of the SiO(2) sol in the precursor solution, the size of the water pools in water-in-oil emulsion increased to 700±320nm compared to 25±5nm when an aqueous CdTe QD solution was used. The size of the beads prepared in the water pools depended strongly on the preparation parameters (water phase injection speed, tetraethyl orthosilicate concentration, reaction time). The beads were easily separated into three size ranges (60±23, 160±40, and 650±200nm) by filtering for further application.

Topics: Cadmium Compounds; Luminescence; Particle Size; Quantum Dots; Silicon Dioxide; Tellurium

A newly designed molecularly imprinted polymer (MIP) material was fabricated and successfully utilized as recognition element to develop a quantum dots (QDs) based MIP-coated composite for selective recognition of the template cytochrome c (Cyt). The composites were synthesized by sol-gel reaction (imprinting process). The imprinting process resulted in an increased affinity of the composites toward the corresponding template. The fluorescence of MIP-coated QDs was stronger quenched by the template versus that of non-imprinted polymer (NIP)-coated QDs, which indicated the composites could recognize the corresponding template. The results of specific experiments further exhibited the recognition ability of the composites. Under optimum conditions, the linear range for Cyt is from 0.97 μM to 24 μM, and the detection limit is 0.41 μM. The new composites integrated the high selectivity of molecular imprinting technology and fluorescence property of QDs and could convert the specific interactions between imprinted cavities and corresponding template to the obvious changes of fluorescence signal. Therefore, a simple and selective sensing system for protein recognition has been realized.

Topics: Biosensing Techniques; Cadmium Compounds; Cytochromes c; Equipment Design; Equipment Failure Analysis; Molecular Probe Techniques; Polymers; Quantum Dots; Spectrometry, Fluorescence; Surface Properties; Tellurium

The purpose of the study was to compare the image generated by a classic panoramic machine equipped with a cadmium telluride sensor capable of digital tomosynthesis and special software with images produced by other popular panoramic X-ray machines using a charge-coupled device and native software for image capture.. Panoramic images were made using a phantom of a human skull on Planmeca ProMax, Planmeca EC Proline, Kodak 8000 and PC-1000. With the last machine we used the PanoACT® software to adjust the entire arch and to adjust the image in selected regions of interest (ROIs). Ten viewers evaluated the images and provided the viewer data. ANOVA for repeated measures was used to compare the means by pairwise comparisons of means.. The image of the entire arch adjusted by the PanoACT® software was statistically superior to the images produced by other machines. The images generated and individually adjusted by PanoACT® were statistically superior to all other images.. The image generated by the cadmium telluride sensor has great potential and can be processed to create superior images to those taken with other machines. Furthermore, the ROI individual images enhanced by the PanoACT® were superior to the entire arch adjusted by the same software.

Topics: Analysis of Variance; Cadmium Compounds; Cracked Tooth Syndrome; Dental Pulp Cavity; Humans; Image Processing, Computer-Assisted; Periodontal Ligament; Phantoms, Imaging; Radiography, Panoramic; Skull; Software; Tellurium; Tomography, X-Ray Computed; Tooth Apex; X-Ray Intensifying Screens

By controlling the reflux time and the quantity of the shell materials, different sizes of thioglycollic acid (TGA) modified CdTe/CdSe core/shell quantum dots were synthesized in aqueous solution. This type of QDs was used for sensitive and selective determination of ascorbic acid in commercial tablets. Under optimal conditions, a good linearity was observed between the relative fluorescence (FL) intensity and the concentration of ascorbic acid in the range of 4.0 to 64.0 μg/mL with a correlation coefficient of 0.9968. The limit of detection was 2.4 μg/mL. This method was applied to the determination of the ascorbic acid in Vitamin C tablets and Vitamin C Yinqiao pills, and satisfactory results were obtained.

Topics: Ascorbic Acid; Cadmium Compounds; Fluorescent Dyes; Hydrogen-Ion Concentration; Molecular Probe Techniques; Quantum Dots; Selenium Compounds; Tellurium

Microchannel is basic functional component of microfluidic chip and every step-forward of its construction technique has been receiving concern all over the world. The present work describes a novel, rapid and simple fabrication technique for building 3D microchannels in poly(dimethyl siloxane) (PDMS) elastomer. These microchannels were used for rapid detection of antigens (E. coli) by quantum dot (QD) based approach. Luminescent QD (CdTe) were synthesized by aqueous method and characterized using high resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy and X-ray diffraction (XRD). The QDs were functionalized with anti-E. coli antibodies for immuno-detection. The reported process allowed easier and faster method of fabrication of circular 3D micochannels and demonstrated their potential use in an immuno-biosensor device.

Topics: Antibodies, Bacterial; Antibodies, Immobilized; Antigens, Bacterial; Biosensing Techniques; Cadmium Compounds; Dimethylpolysiloxanes; Escherichia coli; Microfluidic Analytical Techniques; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Microtechnology; Nanotechnology; Quantum Dots; Spectrometry, Fluorescence; Tellurium; X-Ray Diffraction

The optical transducer of CdTe semiconductor quantum dots (QDs) has been integrated with acetylcholinesterase enzyme (AChE) by the layer-by-layer (LbL) assembly technique, resulting in a highly sensitive biosensor for detection of organophosphorus pesticides (OPs) in vegetables and fruits based on enzyme inhibition mechanism. The detection limits of the proposed biosensors are as low as 1.05 × 10(-11) M for paraoxon and 4.47 × 10(-12) M for parathion, which are significantly better than those of the conventional GC/MS methods or amperometric biosensors (0.5 nM). These biosensors are used for quick determination of low concentrations of OPs in real vegetable and fruit samples and exhibit satisfactory reproducibility and accuracy. Moreover, the stock stability of the biosensors are very good due to the stabilizing environment for the enzyme in the nanostructures made by LbL technique. Many advantages provided by these biosensors, like fluorescent change recognized by naked eyes and mass production with low cost, will facilitate future development of rapid and high-throughput screening of OPs.

Topics: Acetylcholinesterase; Biosensing Techniques; Cadmium Compounds; Enzymes, Immobilized; Food Contamination; Fruit; Microtechnology; Nanostructures; Nanotechnology; Organophosphorus Compounds; Paraoxon; Parathion; Pesticides; Quantum Dots; Tellurium; Vegetables

An easy process was developed to synthesize TiO(2) nanowires sensitized with CdS and CdTeS quantum dots (QDs) requiring no pretreatment of the TiO(2) nanowires prior to nanoparticle generation. CdS and CdTeS nanoparticles were firstly grown by an in situ colloidal method directly onto the TiO(2) surface, hence not requiring subsequent functionalization of the QDs. The resulting nanostructure assembly and composition was confirmed by transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Successful decoration of the TiO(2) nanowires by the QDs was observed by TEM, while XPS spectra provided clear evidence for the coexistence of CdS and CdTeS QDs and TiO(2) nanowires. The electronic structure of the TiO(2) nanowires was preserved as indicated by Raman spectroscopy. Preliminary photocurrent measurements showed that inclusion of Te in CdS QDs improved the photocurrent efficiency. Compared to bare TiO(2) nanowires, CdS/TiO(2) nanoassemblies showed an enhancement in photocurrent efficiency of 300% while CdTeS/TiO(2) presented an improvement of 350%. This study indicates that the generation of strongly anchored CdS and CdTeS QDs on a TiO(2) nanowire surface is achievable without introduction of a linker molecule, whose presence is known to decrease the electron injection efficiency.

Topics: Cadmium Compounds; Nanowires; Particle Size; Photochemical Processes; Quantum Dots; Spectrum Analysis, Raman; Sulfides; Tellurium; Titanium; X-Ray Diffraction

Motivated by the urgent demand for the detection of latent fingerprints using fluorescence-based nanotechnology, this work was devoted to developing a simple synthetic approach to obtain positively charged CdTe QDs with enhanced fluorescence and affinity for the improvement of latent fingerprint detection. Through this synthetic method, the positively charged CdTe-COONH(3)NH(3)(+) QDs were successfully achieved by using hydrazine hydrate as both the surface stabilizer and pH adjuster during the preparation process. In comparison to the negatively charged CdTe-COO(-) QDs prepared by using sodium hydroxide as the pH adjuster, the CdTe-COONH(3)NH(3)(+) QDs showed enhanced fluorescence. The effectiveness of CdTe-COO(-) and CdTe-COONH(3)NH(3)(+) QDs for detection of latent fingerprints present on a large variety of smooth objects was systematically and comparatively studied. The results indicate that the detection of latent fingerprints by using CdTe-COONH(3)NH(3)(+) QDs as fluorescent labeling marks was greatly enhanced, and more characteristic finger ridge details were detected and identified due to their enhanced affinity with latent fingerprints, in comparison to the detection by using CdTe-COO(-) QDs as fluorescent labeling marks. The CdTe-COONH(3)NH(3)(+) QDs show superior detection capability than the CdTe-COO(-) QDs, which greatly improves the applicability of CdTe QDs for practical application in latent fingerprint detection.

Topics: Adsorption; Adult; Cadmium Compounds; Color; Dermatoglyphics; Female; Humans; Hydrogen-Ion Concentration; Male; Nanotechnology; Quantum Dots; Solutions; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Static Electricity; Tellurium; Young Adult

CdTe quantum dots coated with a silica layer containing CdS-like clusters exhibit intense photoluminescence and a spectral red-shift. Biexciton Auger recombination of these particles is examined by transient absorption spectroscopy. A lengthening of the Auger recombination lifetime by a factor of ∼3.5 in the presence of the CdS-like clusters is observed and may contribute to the good PL properties of these nanostructures.

Topics: Cadmium Compounds; Electrons; Quantum Dots; Silicon Dioxide; Spectrometry, Fluorescence; Tellurium

In this paper, different sizes of glutathione-capped CdTe (GSH/CdTe) quantum dots (QDs) have been prepared directly in aqueous solution. The QDs have tunable fluorescence in the range of 510-670 nm, and they also have high photoluminescence quantum yield (PLQY) without any postpreparative treatment. Furthermore, the QDs have strong resistance to photobleaching, and they also have to be considered as cytocompatible. In addition, for the first time, folic acid was covalently conjugated to the GSH/CdTe QDs for imaging of cancer cells, demonstrating their potentially broad application as biolabels.

Topics: Cadmium Compounds; Cell Survival; Diagnostic Imaging; Fluorescence; Glutathione; Hep G2 Cells; Humans; Quantum Dots; Tellurium; Water

CdTe quantum dots (QDs) were used as a highly selective probe for the detection of prion protein. Orange-emitting precipitates appeared within 30s of the addition of recombination prion protein (rPrP) to a solution of green-emitting CdTe QDs. This allowed colorimetric qualitative and semi-quantitative detection of rPrP. The decrease in fluorescence intensity of the supernatant could be used for quantitative detection of rPrP. The fluorescence intensity of the supernatant was inversely proportional to the rPrP concentration from 8 to 200 nmol L(-1) (R(2)=0.9897). Transmission electron microscopy results showed that fibrils existed in the precipitates and these were partly transformed to amyloid plaques after the addition of rPrP.

Topics: Cadmium Compounds; Colorimetry; Microscopy, Electron, Transmission; Models, Biological; Prions; Quantum Dots; Spectrometry, Fluorescence; Tellurium

Three water-soluble CdTe quantum dots (QDs) (green-emitting, yellow-emitting and red-emitting) were synthesised for different refluxing time with 3-mercaptopropionic acid (MPA) as stabiliser. Then the red-emitting CdTe QDs and mouse immunoglobulin G (IgG) were taken as the representative to study the conjugation behaviour of QDs and antibody by a novel immunochromatographic method. After comparing with several methods, that is, direct conjugation, 1-ethyl-3(3-dimethylaminopropyl) carbodiimides hydrochloride (EDC)-mediated conjugation, N-hydroxysuccinimide (NHS)-mediated conjugation, EDC/NHS-mediated conjugation by immunochromatographic strips, EDC and NHS were selected together as coupling agents to conjugate QDs with antibody efficiently. Finally, the K562 leukaemia cells were incubated with the EDC/NHS-mediated conjugates to evaluate the performance in practical application, and the result from fluorescence images showed that it was successfully applied to label cells. The immunochromatographic strip was a superior method to study the conjugation of the fluorophore and antibody.

Topics: Animals; Antibodies, Immobilized; Cadmium Compounds; Carbodiimides; Cell Line, Tumor; Chromatography, Affinity; Fluorescent Dyes; Histocytochemistry; Humans; Hydrogen-Ion Concentration; Immunoglobulin G; Mice; Quantum Dots; Spectrometry, Fluorescence; Succinimides; Tellurium