C/Si Exchange Strategy for Enhanced Photothermal Therapy of Oral Squamous Cell Carcinoma

The photothermal conversion efficiency (PCE) of photothermal agents serves as the primary determinant of the therapeutic efficacy. Enhancing PCE through a simple atomic editing strategy remains a challenging task. Herein, via a C/Si exchange strategy and donor–acceptor engineering, six semiconducting polymers were designed. Compared with C3, Si3 showed a more planar configuration and stronger intramolecular interactions, leading to red-shifted absorption and NIR-II 1330 nm emission. Notably, the PCE of PGB-Si hydrogel encapsulated Si3 reached 53.0%, nearly 3 times that of PGB-C encapsulated C3 of 19.4%. This is one of the most effective strategies to improve PCE through single atom modification. PGB-Si has been successfully applied in oral squamous cell carcinoma therapy by the Cell-line Derived Xenograft model and Patient-Derived Xenograft model. This C/Si exchange strategy provides valuable guidelines for the improvement of PCE, as well as the development of distinctive NIR-II OSCC photothermal polymers.