Gold clusters: A promising NIR-II probe for bioimaging and biosensing

Abstract

Optical imaging and biosensing in the second near-infrared window (NIR-II, 1000–1700 nm) have gained significant interest due to their high signal-to-noise ratio (SNR) and excellent spatial and temporal resolution. These features enable accurate monitoring and treatment of deeper bio-pathological processes. Gold nanoclusters (Au NCs) have emerged as promising candidates for NIR-II emission, offering advantages such as their ultra-small size, outstanding biocompatibility, large Stokes shift, and favorable photoluminescence (PL) properties. This review begins by highlighting the benefits and applications of NIR-II luminescent Au NCs in bioimaging and biosensing. We then explore current strategies to enhance the photoluminescence quantum yield (PLQY) of Au NCs, including techniques such as metal doping, ligand engineering, and the aggregation-induced emission (AIE). Furthermore, we discuss advancements in red-shifting the emission wavelength of Au NCs. Our goal is to provide researchers with fresh insights into improving and fine-tuning the photoluminescent properties of Au NCs, thereby broadening their potential applications in NIR-II bioimaging and biosensing.