Two-step synthesis of high-quality water-soluble near-infrared emitting quantum dots via amphiphilic polymers.

High-quality water-soluble near-infrared emitting quantum dots (QDs) are synthesized using a two-step approach for the first time. The CdS shell efficiently increases the structural stability of PbS QDs during water transfer and leads to good photostability and a significantly enhanced quantum yield as high as 30% in buffer.