In situ synthesis of highly luminescent glutathione-capped CdTe/ZnS quantum dots with biocompatibility

This paper focuses on the in situ synthesis of novel CdTe/ZnS core–shell quantum dots (QDs) in aqueous solution. Glutathione (GSH) was used as both capping reagent and sulfur source for in situ growth of ZnS shell on the CdTe core QDs. The maximum emission wavelengths of the prepared CdTe/ZnS QDs can be simply tuned from 569 nm to 630 nm. The PL quantum yield of CdTe/ZnS QDs synthesized is up to 84%, larger than the original CdTe QDs by around 1.7 times. The PL lifetime results reveal a triexponential decay model of exciton and trap radiation behavior. The average exciton lifetime at room temperature is 17.1 ns for CdTe (2.8 nm) and 27.4 ns for CdTe/ZnS (3.7 nm), respectively. When the solution of QDs is dialyzed for 3 h, 1.17 ppm of Cd2+ is released from CdTe QDs and 0.35 ppm is released from CdTe/ZnS. At the dose of 120 μg/ml QDs, 9.5% of hemolysis was induced by CdTe QDs and 3.9% was induced by CdTe/ZnS QDs. These results indicate that the synthesized glutathione-capped CdTe/ZnS QDs are of less toxicity and better biocompatibility, so that are attractive for use in biological detection and related fields.

The photoluminescence spectra of aqueous CdTe (a) and size-dependent GSH-capped CdTe/ZnS core–shell quantum dots (b–g) with high quantum yields.Figure optionsDownload high-quality image (163 K)Download as PowerPoint slideResearch highlights
► A novel strategy of in situ synthesizing CdTe/ZnS QDs was reported.
► The optimum PL QY of GSH-capped CdTe/ZnS QDs reaches as high as 84%.
► The GSH-capped CdTe/ZnS QDs are less toxic and better biocompatible than CdTe QDs.