CdTe And Cytotoxicity Of CdTe @ ZnS Quantum Dots And Their Impact On Protein Structure

In this work, the CdTe and CdTe@ZnS quantum dots were successfully synthesized in aqueous solution using glutathione (GSH) as a stabilizer. To obtain the optimal operating conditions, the influences of reaction time, concentration ratio and pH on preparation process were discussed. After that, the interaction between QDs and proteins were studied by fluorescence spectrometry.The prepared CdTe QDs were characterized by transmission electron microscopy (TEM), scanning transmission electron microscope (STEM), selected area electron diffraction (SAED), energy dispersive spectroscopy (EDS), and fluorescence spectroscopy to study their structures, properties, morphology and optical properties. The results showed that both CdTe and CdTe@ZnS QDs prepared in aqueous solution have excellent optical stability. The average diameter of CdTe QDs was3.9nm, while the size of CdTe@ZnS QDs increased to4.2nm. SAED showed that the lattice structure of both CdTe and CdTe@ZnS is cubic (zinc blende).The cytotoxicity of CdTe and CdTe@ZnS core-shell quantum dots (QDs) with proteins and cells has been studied. According to discuss structural changes in human serum albumin (HSA) and lysozme (LYS) bound to CdTe QDs, we found that the secondary structure has been impacted significantly from the circular dichroism (CD) results. Proteins reduce their stability with a more flexible folded structure with CdTe QDs, while the proteins with CdTe@ZnS QDs showed weaker change. The fluorescence spectroscopy showed that the fluorescence intensity has been reduced greatly with QDs.From the study of inhibition and morphology of human erythroleukemia cells (K562cell) with QDs, we have demonstrated that the CdTe QDs are highly toxic for cells due to the release of cadmium ions, while the ZnS outlayer has greatly improved the safty of QDs. These results give rise to the evaluation about the safety of QDs application in nanobiotechnology and nanomedicine.