Quantum dots (QDs) as a kind of fluorescent semiconductor nanocrystal possess excellent optical properties, such as high brightness and photostability. Prof. Dai-Wen Pang’s group proposed a spatiotemporal coupling strategy for synthesis of QDs in live cells and further expanded the mode of synthesis from live cells to cell-free quasi-bio-systems. On this basis, they established methods for synthesizing heavy metals-free QDs in the second near-infrared window (from 1000nm to 2100nm) and developed QD-based single-virus tracking technique to systematically investigate the infection behaviors of viruses in live cells and QD-based visual detection for diagnosis of tumors.