Combinatorial discovery of Mo-based polyoxometalate clusters for tumor photothermal therapy and normal cell protection

Nanomaterials with multiple functions such as precision diagnosis, therapeutic efficacy and biosafety are attractive for tumor treatment but remain a technical challenge. In this study, molybdenum (Mo)-based polyoxometalate clusters (Mo-POM) with considerable photothermal conversion efficiency (∼56.6%) and high stability (>30 days) were prepared through a modification of the Folin-Ciocalteu method. These synthetic particles accumulated at the target site, and induced thermal ablation of the tumor following near infrared (NIR) absorption. Furthermore, the Mo-POM effectively scavenged reactive oxygen species (ROS) through charge transfer between Mo(vi) and Mo(v) states, thereby avoiding off-target effects on normal cells and improving the therapeutic efficiency both in vitro and in vivo. Therefore, for the first time, we prepared Mo-POM having two key functions, i.e., photothermal therapy (PTT) for cancer cells and protection of normal cells. These exceptional features may open up the exploration of Mo-POM as new tools for PTT against tumors in clinical applications.