Effects of CdSe and CdSe/ZnS Core/Shell Quantum Dots on Singlet Oxygen Production and Cell Toxicity.

Four types of quantum dots (QDs) with varying emission wavelengths were synthesized in this study. The dots included CdSe and CdSe/ZnS core/shell QDs with short emission wavelengths of 540 nm and 560 nm, respectively, as well as CdSe and CdSe/ZnS core/shell QDs with longer emission wavelengths of 585 nm and 595 nm, respectively. The ligands on the QD surfaces were exchanged with mercaptopropionic acid (MPA) to make them water-soluble. The efficiency of singlet oxygen (1O2) production from both CdSe and CdSe/ZnS core/shell QDs was highest at a QD concentration of 14 μg/ml Singlet oxygen production from the CdSe QDs was higher than that with the CdSe/ZnS core/shell QDs after 1 h of LED470 irradiation. However, the singlet oxygen production of CdSe/ZnS core/shell QDs was much higher than that of CdSe QDs at concentrations above 14 μg/ml. The cytotoxicities of both CdSe and CdSe/ZnS core/shell QDs were investigated using HeLa cells.