Ligand's Role in the Near-Infrared Light-to-Heat Conversion of Au

Non-invasive photothermal therapy (PTT) using nanoscale materials is a promising therapeutic method for cancer treatment, where real-time temperature monitoring is critical for clinical efficacy. This study employs atomically precise Au25 nanoclusters (NCs) that exhibit photothermal activities under near-infrared (NIR) excitation and systematically investigates how the light-to-heat conversion efficiency can be modulated by changing the surface ligands of the Au25 NCs. The photothermal efficiency of these Au25 NCs can be correlated to their photoluminescence (PL) lifetime, which is strongly influenced by the surface-capping ligands. Remarkably, by rigidifying the surface ligands within the protein scaffold, photothermal conversion efficiency of the NCs is further strikingly enhanced. Furthermore, we highlight the bimodal role of Au25 NCs as photothermal agents and luminescent lifetime-based nanothermometer. Indeed, Au25 NCs exhibit a linear correlation between the lifetime and temperature, enabling real-time monitoring of both local (in the NCs) and global (in the solutions) temperature changes during PTT.