Green synthesis of MPA-capped CdTe/CdSe quantum dots at different pH and its effect on the cell viability of fibroblast histiocytoma cells

Quantum dots (QDs) have attracted great attention due to their superior optical properties compared to organic dyes. However, the cytotoxicity of the QDs has been a major source of concern for their biological applications thus, finding solution to this problem has become an interesting area of research. We herein report green synthesis of mercaptopropionic acid (MPA) capped CdTe/CdSe core/shell QDs at different pH and their characterization using UV–vis absorption and photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). By varying the pH of the reaction, the temporal evolution of the optical properties and cytotoxicity of the QDs were monitored. The optical analysis showed that, increase in the solution pH, produce CdTe/CdSe QDs with excellent optical properties such as red-emission with enhanced luminescence intensity and narrow full width at half maximum (FWHM). The cell viability assay of QDs using fibroblast histiocytoma (KM-Luc/GFP) cells indicated improved cell viability as the pH of the reaction increased. The improved cell viability as the pH increase is attributed to the higher stability of the material and hence lower release of Cd²⁺.