Controlled Synthesis of Ag<sub>2</sub>Te@Ag<sub>2</sub>S Core–Shell Quantum Dots with Enhanced and Tunable Fluorescence in the Second Near‐Infrared Window
Yejun Zhang, Hongchao Yang, Xinyi An, Zan Wang, Xiaohu Yang, Mengxuan Yu, Rong Zhang, Ziqiang Sun, Qiangbin Wang
Abstract
Abstract Fluorescence in the second near‐infrared window (NIR‐II, 900–1700 nm) has drawn great interest for bioimaging, owing to its high tissue penetration depth and high spatiotemporal resolution. NIR‐II fluorophores with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. In this work, a Ag‐rich Ag 2 Te quantum dots (QDs) surface with sulfur source is successfully engineered to prepare a larger bandgap of Ag 2 S shell to passivate the Ag 2 Te core via a facile colloidal route, which greatly enhances the PLQY of Ag 2 Te QDs and significantly improves the stability of Ag 2 Te QDs. This strategy works well with different sized core Ag 2 Te QDs so that the NIR‐II PL can be tuned in a wide range. In vivo imaging using the as‐prepared Ag 2 Te@Ag 2 S QDs presents much higher spatial resolution images of organs and vascular structures as compared with the same dose of Ag 2 Te nanoprobes administrated, suggesting the success of the core–shell synthetic strategy and the potential biomedical applications of core–shell NIR‐II nanoprobes.