Facile synthesis of highly luminescent ZnSe(S) alloyed quantum dot for biomedical imaging

An alloyed complex of zinc, sulphur and selenium was synthesized in a controlled fashion using 3-mercaptopropionic acid (MPA) surfactant to obtain a new class of biocompatible, highly luminescent imaging probes. These ZnSe(S) alloyed quantum dots (QDs) exhibited a five fold enhancement in photoluminescence over the native ZnSe nanocrystals. The enhancement in photoluminescence was brought about without any post-preparative surface treatments, under ambient conditions. 3-mercaptopropionic acid (MPA) was found to optimally stabilize the ZnSe(S) alloyed system. The incorporation of S2− from MPA after prolonged refluxing time enabled the formation of ZnSe(S) alloyed QDs with low cytotoxicity. The in vitro assays revealed the synergistic enhancement of photoluminescence with enhancement in dispersibility and high biocompatibility for the ZnSe(S) system. The experimental findings give us a novel range of blue-emitting, Zn-based high luminescence QDs for development of nano-probes for bioimaging applications.

► ZnSe(S) alloyed QDs were synthesized by a one-pot aqueous route.
► Five-fold photobrightening was obtained in ZnSe(S) compared to ZnSe QDs.
► Precursor ratios were optimized to have an efficient alloyed QD system.
► The alloyed QDs retain high biocompatibility and dispersibilty as the native ZnSe QDs.
► The so prepared ZnSe(S) QDs have high potential for biomedical imaging.