TOWARDS THE PREPARATION OF HIGHLY LUMINESCENT WATER-SOLUBLE QUANTUM DOTS

Abstract

Quantum dots (QDs) are the semiconductor crystals of three dimensions in nanometer scale exhibiting quantum confinement effect. The size-dependent optical properties trigger numerous applications based on QDs. In biological research, highly luminescent water-soluble QDs are inevitably required. The investigations described in this study bridge the gap between the as-synthesized QDs in the organic phase and the ones ready for biological application. Firstly, an aqueous synthetic route of CdTe/CdS core/shell QDs under ambient air atmosphere without inert gas protection throughout the entire fabrication process was developed. The obtained QDs were highly luminescent with a widely tunable photoluminescence emission window of 535-815 nm. Secondly, a facile and general method was devised to transfer oleophilic QDs to aqueous media with high transfer efficiency (~100%) and essentially retained PLQY (> 80%). The transfer is based on ligand exchange mediated by ethylenediamine. This method was further employed to assemble DNA strands on QDs.