One-step synthesis of nontoxic Ag-In-Zn-S quantum dots via microwave-assisted hydrothermal method for bioimaging

Synthesis of nontoxic quantum dots (QDs) with excellent optical properties in aqueous phase to replace organic dyes with photobleaching drawbacks used in bioimaging has become a research priority. Herein, water-soluble Ag-In-Zn-S (AIZS) QDs were prepared by microwave-assisted hydrothermal method at 110 °C for 40 min. The luminescence peak of AIZS QDs was varied from 684.5 nm to 576.2 nm when the Ag/In molar ratio was changed in the range of 1/2–1/10. A clear blue-shift of PL peak from 616.8 nm to 551.5 nm was observed with increasing Zn 2+ element with the Ag/Zn molar ratio in the range of 1/0–1/14, indicating that the increase of Zn 2+ content caused the increase of band gap. The AIZS QDs exhibit the highest photoluminescent quantum yield (PLQY) of 20.67 % with the molar ratio of Ag/In/Zn=1/6/2, and fluorescence lifetime upped to 294.69 ns. Finally, human hepatocellular carcinomas (HepG2) cells and Hela cells were incubated with AIZS QDs solution at different concentrations and were found to have a high survival rate. Furthermore, HepG2 cells emitted bright yellow light when stimulated upon UV excitation, indicating that AIZS QDs can be applied in bioimaging field.