Near Infrared Ag2S Quantum Dots: Synthesis, Functionalization, and In Vivo Stem Cell Tracking Applications

Abstract

Near infrared fluorescent semiconductor quantum dots (QDs) have become one of the most widely used nanoprobes in biomedical imaging researches due to their high optical and chemical stability, tunable emission, and the ability to image multiple targets. In particular, the recently developed Ag2S QDs emitting in the second near infrared window (NIR-II, 1000–1700 nm) have significantly improved the tissue penetration depth, sensitivity, temporal resolution, and spatial resolution of QD-based fluorescence imaging because of the minimal absorption and scattering of NIR-II light in tissues. Thus, the Ag2S QD-based fluorescence imaging has been successfully applied in numerous biomedical studies including in vivo stem cell tracking. In this chapter, we introduce methods for synthesis of photoluminescent Ag2S QDs, summarize the surface functionalization strategies for preparing highly stable and cell-targeting Ag2S QDs, and systematically illustrate the applications of Ag2S QDs in stem cell tracking.