Quantum dots (QDs) as a kind of fluorescent nanomaterial possess excellent optical properties, such as high brightness and photostability. Pang Daiwen's group proposed a spatiotemporal coupling strategy for producing QDs and 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, developed QD-based single-virus tracking technique to systematically investigate the infection behaviors of viruses in live cells, and built QD-based visual detection approaches for the detection and diagnosis of tumors.