Emerging NIR-II Luminescent Gold Nanoclusters for In Vivo Bioimaging

Gold nanoclusters (AuNCs) with near-infrared II (NIR-II) photoluminescence (PL) have emerged as novel bioimaging probes for in vivo disease diagnosis. So far, it still lacks a systematic review focusing on the synthesis, PL tuning, and in vivo imaging of NIR-II luminescent AuNCs. In this review, we briefly introduce the synthesis of NIR-II luminescent AuNCs using various surface ligands. We discuss the origins and properties of NIR-II PL in AuNCs, and summarize the strategies for improving and/or tuning NIR-II PL emissions. We also provide an overview of the recent progress in the application of AuNCs in tumor-targeted imaging, molecular imaging, and other areas (such as the sensitive imaging of bones, vessels, lymph nodes, etc.). Finally, we present the prospects and challenges in the field of NIR-II luminescent AuNCs and related imaging applications, expecting to offer comprehensive understanding of this field, and thereby deepening and broadening the biological application of AuNCs.