tellurium and cadmium-sulfate

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

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

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

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

Nanotechnology has gained increasing commercial attention over recent years and its use has raised concerns about its potential release in the environment. The purpose of this study was to determine the size distribution of CdTe in freshwater, bioavailability and potential toxic effects of cadmium telluride quantum dots (CdTe QD) to the freshwater mussel Elliptio complanata. Mussels were exposed to increasing concentrations (0 to 8 mg Cd L(-1)) of CdTe and 0.5 mg/L CdSO4 for 24 h at 15 degrees C to examine the initial uptake and toxic effects of Cd from CdTe QDs and dissolved CdSO4. After the exposure period, Cd bioaccumulation in the gills, digestive gland and gonad tissues and metallothionein (MT) levels were determined. The results revealed that about 80% of Cd was retained by a 450 nm pore filter (aggregates) and that 14% of the Cd was in the dissolved phase (i.e., eluted through a 1 kDa ultrafiltration membrane) which suggested that uncoated CdTe QDs were not stable in freshwater. In mussels, Cd was accumulated principally by the gills and digestive gland and the bioaccumulation factors of Cd from CdTe were similar to that of dissolved Cd. Indeed, tissue-levels of Cd were below the proportion of dissolved Cd from CdTe which suggests that Cd rather comes from the dissociation of Cd from the ingested QDs than from the internalization of the QDs in mussel tissues. The levels of MT were induced in both the digestive gland and gonad but were readily decreased in the gills by both CdTe and CdSO4. The observed decrease in the metallic form of MT might result from the oxidative stress by CdTe and dissolved Cd. In conclusion, uncoated CdTe QD in freshwater leads to aggregates and a dissolved component of Cd where the latter explained the contribution of the observed accumulation pattern in mussel tissues and effects on MT levels in mussels.

Topics: Animals; Biological Availability; Bivalvia; Body Burden; Cadmium Compounds; Digestive System; Dose-Response Relationship, Drug; Fresh Water; Gills; Gonads; Metallothionein; Oxidative Stress; Quantum Dots; Solubility; Sulfates; Tellurium; Up-Regulation; Water Pollutants, Chemical

The purpose of this study was to examine the toxic effects of cadmium-telluride (CdTe) quantum dots on freshwater mussels. Elliption complanata mussels were exposed to increasing concentrations of CdTe (0, 1.6, 4 and 8 mg/L) and cadmium sulfate (CdSO(4), 0.5mg/L) for 24h at 15 degrees C. After the exposure period, they were removed for assessments of immunocompetence, oxidative stress (lipid peroxidation) and genotoxicity (DNA strand breaks). Preliminary experiments revealed that CdTe dissolved in aquarium water tended to aggregate in the particulate phase (85%) while 15% of CdTe was found in the dissolved phase. Immunotoxicity was characterized by a significant decrease in the number of hemocytes capable of ingesting fluorescent beads, and hemocyte viability. The cytotoxic capacity of hemocytes to lyse mammalian K-562 cells was significantly increased, but the number of circulating hemocytes remained unchanged. Lipid peroxidation was significantly increased at a threshold concentration of 5.6 mg/L in gills and significantly reduced in digestive glands at a threshold concentration <1.6 mg/L CdTe. The levels of DNA strand breaks were significantly reduced in gills at <1.6 mg/L CdTe. In digestive glands, a transient but marginal increase in DNA strand breaks occurred at the lowest concentration and dropped significantly at the higher concentrations. A multivariate analysis revealed that the various response patterns differed based on the concentration of CdTe, thus permitting the identification of biomarkers associated with the form (colloidal vs. molecular) of cadmium.

Topics: Animals; Bivalvia; Cadmium Compounds; Cell Line; Digestive System; Discriminant Analysis; DNA Breaks; Fresh Water; Gills; Hemocytes; Lipid Peroxidation; Oxidative Stress; Particle Size; Phagocytosis; Statistics as Topic; Sulfates; Tellurium; Water Pollutants, Chemical