Cytotoxicity and Phototoxicity of Red Fluorescent Nontargeted Quantum Dots

Medicinal applications of luminescent quantum dots (QDs) are of growing interest. In spite of the fact that their fabrication and imaging functions have been extensively investigated during the last decade, very little is known on curative potential of the QDs. In this study, we focus on cytotoxicity and phototoxicity of red-absorbing ( <;630 nm) nontargeted CdSe/ZnS QDs with fluorescence peak at 655 nm. The studied QDs in the range of concentrations studied (0-100 nM) showed no prominent cytotoxicity toward prostate carcinoma Du145 cells, while retardation of the cell growth at higher concentrations (200-400 nM) was most likely caused by borate buffer used to suspend the QDs. Under exposure to blue or red light of the cells pretreated with the QDs, there was a tendency of photodynamic action of the QDs. However, the effect was not significant, and photosensitizing potential of QDs has yet to be demonstrated in the future by using QD immunoconjugates to target more vital cellular sites.