tellurium and 2-mercaptoacetate

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

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

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

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

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

Reviewing the mode of interaction between this kind of active pharmaceutical ingredients and DNA has received much more attention in current years. Anthracycline drugs such as Epirubicin are frequently used in cancer treatment for breast cancer treatment. In the present study, the Epirubicin -calf thymus DNA interaction was investigated by using spectroscopic, fluorimetric and molecular docking methods. Water-soluble quantum dots (QDs) with nanometric particle size fabricated and characterized by transmission electron microscope and photon correlation spectroscopy. The binding constant value and the free energy change for this interaction were obtained to be 3.00×106 M-1 and -42.26 kJ mol-1, using the spectroscopic method and docking investigations, respectively. Additionally, fluorescent thioglycolic acid-capped CdTe QDs were used for investigation of EPI and DNA interaction. Epirubicin as a quencher quenched the fluorescence of CdTe QDs after electrostatic adsorption on the surface of QDs. With the addition of DNA, EPI will be desorbed from the surface of CdTe QDs, inserted into the DNA. Subsequently, fluorescence changes of QDs were used for calculation of binding constant value, which was in good agreement with that obtained by the spectroscopic method. By the comparison of the achieved results, the intercalation mode of interaction between Epirubicin and DNA proved.

Topics: Antibiotics, Antineoplastic; Cadmium Chloride; DNA; Epirubicin; Fluorescence; Hydrophobic and Hydrophilic Interactions; Molecular Conformation; Molecular Docking Simulation; Nanoparticles; Particle Size; Quantum Dots; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates

The potential toxicity of Quantum dots (QDs) should be assessed comprehensively for their fast spreading applications. Many studies have shown the toxicity of QDs is associated with their surface ligands. In this work, two analog ligands with one carbon difference, 2-mercaptoacetic acid (TGA) and 3-mercaptopropionic acid (MPA) were used as coating materials in the syntheses of two types of CdTe QDs with similar physicochemical properties. Then the biological effects of QDs on isolated mitochondria were studied. It was found that the two types of QDs could impair mitochondrial respiration and induce mitochondrial permeability transition (MPT). However, as compared with TGA-CdTe QDs, MPA-CdTe QDs had a stronger effect on MPT. The weaker effect of TGA-CdTe QDs on MPT might be owing to their better stability and thus less amount of released Cd

Topics: 3-Mercaptopropionic Acid; Cadmium Compounds; Ligands; Mitochondria; Quantum Dots; Tellurium; Thioglycolates

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

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

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

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

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

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

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

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

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

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

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

In this paper, we have presented a novel CdTe quantum dots (QDs) based fluorescent sensor for visual and turn-on sensing of citrate in human urine samples. The europium ion (Eu(3+)) can lead to the fluorescence quenching of thioglycollic acid (TGA) modified CdTe QDs due to photoinduced electron transfer accompanied by the change of emission color from yellow to orange. Next, addition of citrate breaks the preformed assembly because citrate can replace the CdTe QDs, based on the fact that the Eu(3+) ion displays higher affinity with citrate than the CdTe QDs. Thus the photoinduced electron transfer is switched off, and the fluorescence emission of CdTe QDs is rapidly (within 5min) recovered, simultaneously, the orange emission color restores to yellow. Such proposed strategy may conveniently discriminate the patient of renal stone from normal person by naked eyes. In addition to visualization detection, the fluorescence responses can be used for well quantifying citrate in the range of 0.67-133μM. So, the present, simple, low-cost and visualized citrate fluorescence sensor has great potential in the applications for earlier screening in clinical detection.

Topics: Adult; Cadmium; Citric Acid; Europium; Female; Fluorescence; High-Throughput Screening Assays; Humans; Male; Microscopy, Electron, Transmission; Quantum Dots; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tellurium; Thioglycolates; Urinalysis; Young Adult

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 main objective of this work is to synthesize CdTe quantum dots (QDs) conjugated with Concanavalin A (Con A) as a novel biosensor to be selective and specific for the detection of Lipopolysaccharide (LPS). In addition, the conjugated CdTe QDs-Con A was used as fluorescence labels to capture Serratia marcescens bacteria through the recognition between CdTe QDs-Con A and LPS of S. marcescens. The appearance of the lattice plans in the high resolution transmission electron photograph indicated a high crystalline with an average size of 4-5 nm for the CdTe QDs. The results showed that the relative fluorescence intensity of CdTe QDs-Con A decreased linearly with LPS concentration in the range from 10 to 90 fg/mL and with correlation coefficient (R(2)) equal to 0.9713. LPS surrounding the S. marcescens bacteria was bound to the CdTe QDs-Con A and leads to quenching of PL intensity. It was found that a good linear relationship between the relative PL intensity and the logarithmic of cell population of S. marcescens in range from 1×10 to 1×10(6) CFU/mL at pH 7 with R(2) of 0.952 was established.

Topics: Biosensing Techniques; Cadmium Compounds; Concanavalin A; Fluorescence; Lipopolysaccharides; Quantum Dots; Serratia marcescens; Spectrometry, Fluorescence; Tellurium; Thioglycolates

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

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

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

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

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

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

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

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

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

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 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

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

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

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

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

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

We report herein on the development of a synthetic route towards SWNT/polyelectrolyte/QD nanohybrids. On one hand, negatively charged thioglycolic acid capped CdTe QDs were prepared via an aqueous solution based synthesis. On the other hand, SWNTs were coated with a positively charged polyelectrolyte. By virtue of electrostatic interactions between QDs and SWNTs, SWNT/ polyelectrolyte/QD nanohybrids were realized, whose formation was corroborated by thorough spectroscopic and microscopic investigations. Of particular relevance are changes of the QD related emission - quantum yields and lifetimes - upon their integration into the nanohybrids. The latter is indicative for electronic communication between both the photo- and redoxactive constituents, namely QDs and SWNTs, whose nature is electron transfer.

Topics: Cadmium; Electrochemistry; Electrolytes; Electron Transport; Green Chemistry Technology; Nanotubes; Photochemistry; Photosynthesis; Quantum Dots; Solar Energy; Solutions; Spectrum Analysis; Static Electricity; Sunlight; Tellurium; Thioglycolates; Water

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

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

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

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

A novel fluorescent probe for Cu(2+) determination based on the fluorescence quenching of glyphosate (Glyp)-functionalized quantum dots (QDs) was firstly reported. Glyp had been used to modify the surface of QDs to form Glyp-functionalized QDs following the capping of thioglycolic acid on the core-shell CdTe/CdS QDs. Under the optimal conditions, the response was linearly proportional to the concentration of Cu(2+) between 2.4×10(-2)μg mL(-1) and 28μg mL(-1), with a detection limit of 1.3×10(-3)μg mL(-1) (3δ). The Glyp-functionalized QDs fluorescent probe offers good sensitivity and selectivity for detecting Cu(2+). The fluorescent probe was successfully used for the determination of Cu(2+) in environmental samples. The mechanism of reaction was also discussed.

Topics: Cadmium Compounds; Copper; Environmental Monitoring; Fluorescence; Fluorescent Dyes; Glycine; Glyphosate; Ions; Limit of Detection; Microscopy, Electron, Transmission; Molecular Probe Techniques; Quantum Dots; Sensitivity and Specificity; Sulfides; Tellurium; Thioglycolates; Wastewater

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

Water-soluble CdTe quantum dots (QDs) stabilized by thioglycolic acid (TGA) with high quantum yield were synthesized. And the small biomolecule 17beta-amino-estradiol was marked successfully by CdTe QDs. The analysis of UV-Vis spectroscopy, fluorescence spectroscopy, infrared spectroscopy and inverted microscope photographs showed that the surface carboxyl of CdTe quantum dots conjugated with the amino of 17beta-amino-estradiol through the activation of N-hydroxysuccinimide. 17beta-amino-estradiol marked by CdTe QDs successfully provided an experimental basis for new drug screening model.

Topics: Cadmium Compounds; Estrogens; Quantum Dots; Spectrometry, Fluorescence; Succinimides; Tellurium; Thioglycolates; Water

Engineered nanoparticles are increasingly used in consumer products. While the potential of these products hold great promise, it is not known what potential toxic effects these nanomaterials may have on human health. There is a need to develop affordable, systematic, short-term in vitro assays aimed at allowing rapid assessment of potential toxicity. The method reported in this paper describes a system in which the intestinal lining is mimicked (Caco-2 human intestinal cell line) and provides an environment in which quantum dots (QDs), and possibly other nanomaterials, can be applied. Transepithelial electrical resistance (TEER) measurements assessed whether the epithelial integrity was breached because of QD exposure. QDs were suspended in calcium/magnesium-free phosphate buffered saline to study non-aggregated QDs. To maintain cell integrity, normal cell culture conditions were retained below the epithelium to provide necessary nutrients and ions. Toxicity studies completed here show that the nanosized QDs coated with hydrophilic thioglycolate capping ligands purchased for these experiments caused disruption in the epithelium monolayer and cell death at 0.1mg/L of QDs. This toxicity was caused by the nano-size of the QDs rather than the cadmium ions or the sodium thioglycolate capping ligands. Aggregated QDs did not cause toxicity as measured by TEER.

Topics: Caco-2 Cells; Cadmium Compounds; Cell Death; Electric Impedance; Humans; Ligands; Particle Size; Quantum Dots; Tellurium; Thioglycolates; Toxicity Tests