Nanocarbon Framework-Supported Ultrafine Mo2C@MoOx Nanoclusters for Photothermal-Enhanced Tumor-Specific Tandem Catalysis Therapy.

Recent advances in the synthesis of multifunctional nanomaterials create new opportunities for the rational design of multimodal chemodynamic therapy (CDT) agents. Precisely tailoring the nanostructure and composition of CDT nanoagents for maximum efficacy remains a challenge. Herein, we report the successful synthesis of nanocarbon framework-supported ultrafine Mo2C@MoOx nanoclusters (C/Mo2C@MoOx) via a pyrolysis of a Mo/ZIF-8 MOF precursor at 900 °C followed by mild surface oxidation. The developed C/Mo2C@MoOx composite demonstrated outstanding performance in photothermal-enhanced tumor-specific tandem catalysis therapy. Specifically, C/Mo2C@MoOx efficiently catalyzed the conversion of endogenous H2O2 to cytotoxic 1O2 via a Russell mechanism, while also converting the O2 byproduct to cytotoxic ·O2- via an oxidase-like mechanism. A high dispersion of active Mo5+ sites in the exposed MoOx shell enhanced the reactive oxygen species (ROS)-generating efficiency of C/Mo2C@MoOx. Moreover, the Mo2C core in the ultrafine Mo2C@MoOx nanoclusters allowed NIR-II (1064 nm)-driven photothermal heating, which significantly boosted the CDT process through photothermal effects. Additionally, the CDT process relied on a redox cycle involving Mo5+/Mo6+ species, which could be sustained by glutathione (GSH) consumption. Given these advantages, C/Mo2C@MoOx demonstrated remarkable synergistic therapeutic efficacy for cancer treatment (both in vitro and in vivo) through tumor microenvironment-stimulated generation of multiple ROS and NIR-II photothermal activity.