P. Rodríguez-Fragoso

Synthesis, characterization and toxicological evaluation of maltodextrin capped cadmium sulfide nanoparticles in human cell lines and chicken embryos

BackgroundSemiconductor Quantum dots (QDs) have become quite popular thanks to their properties and wide use in biological and biomedical studies. However, these same properties entail new challenges in understanding, predicting, and managing potential adverse health effects following exposure. Cadmium and selenium, which are the major components of the majority of quantum dots, are known to be acutely and chronically toxic to cells and organisms. Protecting the core of nanoparticles can, to some degree, control the toxicity related to cadmium and selenium leakage.ResultsThis study successfully synthesized and characterized maltodextrin coated cadmium sulfide semiconductor nanoparticles. The results show that CdS-MD nanoparticles are cytotoxic and embryotoxic. CdS-MD nanoparticles in low concentrations (4.92 and 6.56 nM) lightly increased the number of HepG2 cell. A reduction in MDA-MB-231 cells was observed with concentrations higher than 4.92 nM in a dose response manner, while Caco-2 cells showed an important increase starting at 1.64 nM. CdS-MD nanoparticles induced cell death by apoptosis and necrosis in MDA-MD-231 cells starting at 8.20 nM concentrations in a dose response manner. The exposure of these cells to 11.48-14.76 nM of CdS-MD nanoparticles induced ROS production. The analysis of cell proliferation in MDA-MB-231 showed different effects. Low concentrations (1.64 nM) increased cell proliferation (6%) at 7 days (p < 0.05). However, higher concentrations (>4.92 nM) increased cell proliferation in a dose response manner (15-30%) at 7 days. Exposures of chicken embryos to CdS-MD nanoparticles resulted in a dose-dependent increase in anomalies that, starting at 9.84 nM, centered on the heart, central nervous system, placodes, neural tube and somites. No toxic alterations were observed with concentrations of < 3.28 nM, neither in cells nor chicken embryos.ConclusionsOur results indicate that CdS-MD nanoparticles induce cell death and alter cell proliferation in human cell lines at concentrations higher than 4.92 nM. We also demonstrated that they are embryotoxic. However, no toxic effects were observed with doses lower than 3.28 nM in neither cells nor chicken embryos. The CdS-MD nanoparticles used in this study can be potentially used in bio-imaging applications. However, further studies using mammalian species are required in order to discard more toxic effects.

Pharmacokinetics of Maltodextrin Coated Cadmium Sulfide Quantum Dots in Rats

Quantum Dots (QDs) are rapidly becoming popular as novel tools for theragnostic purposes. This report evaluates the pharmacokinetics parameters of CdS-MDx QDs of different tissues following a single dose i.p. to rodents at several time points, as a model system for determining their tissue uptake, time of residence and elimination. We employed an analysis of tissue images using fluorescence microscopy and tissue homogenates by spectroscopy to identify and measure the CdS-MDx QDs content and analyze the concentration of QDs in each tissue at predetermined time intervals. The pharmacokinetics analysis of CdS-MDx QDs (Cmax, Tmax, AUC0-t, AUC0-∞, Ke and MRT) were different for each tissue after a single dose of QDs during 360 h. Liver and kidney tissues took up the most QDs, but their Ke and MRT evidenced a rapid kinetic of elimination, suggesting QDs might get eliminated by these organs. Our data clearly showed that CdS-MDx QDs were not completely cleared from in vivo systems after 360 h. CdS-MDx QDs appears to be nanomaterials with favorable pharmacokinetics properties to develop novel therapeutic and diagnostic modalities.

Potential Harm of Maltodextrin‐Coated Cadmium Sulfide Quantum Dots in Embryos and Fetuses

Over the past years, there has been significant interest in the study of nanoparticles for clinical applications, particularly quantum dots (QDs). However, previous studies have also shown that QDs can reach the embryo through the placenta, a natural barrier for a large variety of organic substances with diverse molecular structures, and may cause developmental deformities. Due to its essential role in a toxicological profile and its relevance to human safety, knowledge regarding embryotoxicity is of great importance. Previous studies by this research group have shown that CdS‐maltodextrin QDs are biocompatible and nontoxic to cells and animals; however, QDs are able to induce embryotoxic effects. Therefore, as an effort to further address the issue, we studied the effects of CdS‐maltodextrin QDs on embryo and fetus development using an embryo‐ toxicity and teratogenicity assay on chicken embryos. Chicken embryos exposed to CdS‐maltodextrin QDs (0.001, 0.01, 0.1 and 1 μg/kg) in ovo for 72 h showed growth and developmental alterations during the early stage and at the end of their development in a dose‐dependent manner. Decreased development was observed during early stages (Stages 9/10 on the Hamburger‐Hamilton scale) when compared with untreated eggs (Stage 13). Chicken embryos exposed to lower CdS‐maltodextrin QDs doses (0.01, 0.1 and 1 ng/kg) and incubated in ovo for 21 h also showed growth and development alterations during the early stages and at the end of their development in a dose‐ dependent manner. However, reduced development was observed at the end of the development period (21 days), and this was associated with death of the chick. Current studies have also shown that CdS‐dextrin induces embryotoxicity and teratogenicity, affecting mainly the CNS, the neural tube and somites in chicken embryos. The nature of the observed abnormalities suggests that these effects could be directly associated with nanoparticle concentrations affecting somitogenesis. Therefore, according to the

InGaAsSb p‐n Heterojunctions Studied by Photoluminescence and Photoacoustic Spectroscopies for Photovoltaic Applications

By using the liquid phase epitaxy (LPE) technique we report the growth of p‐n InGaAsSb layer structures on top of (100) GaSb substrates under lattice‐matched conditions. The 1st layer was an n‐type InGaAsSb (Te‐doped), whereas the 2nd layer was a p‐type InGaAsSb (Zn‐doped). The Zn‐doped InGaAsSb layer in the heterostructure was characterized using microRaman spectroscopy, the photoacoustic (PA) technique, and the low temperature photoluminescence (PL) spectroscopy. From the Raman spectra we found the presence of the LO GaAs‐like, the TO (GaSb+InAs) and the TO and LO InSb modes with energies that agree with reported results for this type of heterostructures. The PA characterization shows that for those samples with lower Zn‐doping levels, the non‐radiative recombination times are higher indicating better crystalline quality. The photoluminescence (PL) spectra showed bands centered at 2015, 1980 and 2120 nm for the samples doped with 0.23, 0.54 and 0.89 mg of Zn in the melt solution. For the first two sampl...