A near-infrared responsive germanium complex of Ge/GeO₂ for targeted tumor phototherapy

The development of photoactive nanomaterials with high biocompatibility for targeted tumor phototherapy is of great significance for antitumor applications; this study presents a novel phototherapeutic agent, the Ge/GeO₂ complex, which shows broad photoabsorption in the near infrared (NIR) region. As a result, it can synchronously produce reactive oxygen species (ROS) and heat under NIR irradiation. After being loaded onto macrophages, Ge/GeO₂ could be delivered to tumors in a targeted fashion. Combining the abovementioned merits together, macrophage-loaded Ge/GeO₂ realized in vivo synergetic photothermal and photodynamic outcomes to completely remove solid tumors in mice via intravenous administration. In this study, B-ultrasonography was also employed to monitor the tumor evolution after phototherapy, revealing a sequential process of tumor necrosis, liquefaction/softening, and finally disappearance. In addition, Ge/GeO₂ proposed in this study shows negligible cytotoxicity and hematotoxicity, especially after being loaded onto macrophages.