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

Abstract

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 Zn2+ element with the Ag/Zn molar ratio in the range of 1/0–1/14, indicating that the increase of Zn2+ 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.