Luminescent gold nanoclusters for in vivo tumor imaging

Fluorescent gold nanoclusters (AuNCs) are emerging as novel imaging contrast agents. These molecules offer excellent prospects for non-invasive tumor diagnosis strategies because of their ultra-small size, tunable emissions from the visible to the near-infrared range, excellent biocompatibility, and suitable pharmacokinetic properties. In this tutorial review, we introduce the physiological features of the tumor microenvironment, followed by a description of AuNC pharmacokinetics. Next, we outline the strategies used to deliver AuNCs specifically to tumor tissues for in vivo tumor imaging. Finally, examples are presented to highlight the application potential of AuNCs for in vivo tumor imaging.