Cathodic stripping synthesis and cytotoxity studies of glutathione-capped CdTe quantum dots.

A cathodic stripping of Te precursor in the presence of Cd2+ and biocompatible glutathione (GSH) was reported for facile synthesis of lowly cytotoxic and highly luminescent CdTe quantum dots (QDs) in aqueous solution. The photoluminescence, electrogenerated chemiluminescence (ECL), toxicity, and cyto-osmosis of the QDs were evaluated to reveal their potential bio-applications. The morphology and composition of as-prepared QDs were investigated by HRTEM and powder XRD spectroscopy, which indicated that the QDs consisted of a CdTe core coated with a CdS shell. The obtained CdTe/CdS core/shell QDs possessed good crystallinity, narrow monodispersity and long-term stability. These QDs showed high fluorescence quantum yields of 49% to 63% over a broad spectral range of 540-650 nm. Efficient and stable ECL of QDs was observed on the anodic potential region upon the electrode potential cycled between 1.5 and -2.0 V versus Ag/AgCl. Furthermore, human liver cancer HepG2 cells were chosen as model cells for toxicity assay of QDs. Effects of the concentration, size, and incubation time of CdTe QDs capped with GSH or mercaptoacetic acid (MAA) on the cell metabolic viability and cyto-osmosis were evaluated. GSH-capped CdTe QDs could infiltrate cytomembrane and karyothecas, and were less cytotoxic than MAA-capped ones under the same experimental conditions. The reported CdTe QDs could be good candidates of fluorescent and ECL probes for biosensing and cell imaging.