Controlled synthesis, optical properties and cytotoxicity studies of CdSe-poly(lactic acid) multifunctional nanocomposites by ring-opening polymerization.

A facile synthetic route has been developed for the covalent grafting of biocompatible poly(lactic acid) (PLA) onto CdSe Quantum Dots (QDs) using surface initiated ring opening polymerization (ROP) to afford CdSe-g-PLA nanocomposites. At first, 2-mercaptoethanol (ME) capped CdSe QDs were synthesized through a wet chemical process. The surface initiated ROP of lactide was accomplished with Sn(Oct)2 to give CdSe-g-PLA nanocomposites having surface hydroxyl functionality. FT-IR data suggested that a robust covalent bond was formed between ME capped CdSe QDs and polymer moieties. The grafting density of PLA on CdSe QDs was found to be moderate as measured by TGA analysis. The CdSe QDs were well dispersed in CdSe-g-PLA nanocomposites matrices as captured by TEM. The cubic phase crystal structure of CdSe QDs in the nanocomposites was determined by XRD. The optical properties of the CdSe-g-PLA nanocomposites were investigated by UV-vis and photoluminescence spectroscopy which suggested their potentialities as optical materials in biomedical application. Cell viability studies revealed that the biocompatibility of CdSe QDs was improved upon PLA immobilization.