Self-Adaptive Sn-Fe Electron Pair Centers in Pt/SnFe₂O₄ for Anti-Tumor Synergistic Therapy

Despite the multiple advantages of high tissue penetration depth, selectivity, and noninvasiveness of photothermal-assisted antitumor synergistic therapy, developing photothermal agents with multifunctional characteristics, desirable tumor therapeutic effects, and biological stability remains a key challenge. Herein, an electronic structure-regulated strategy is proposed to activate self-adaptive Sn-Fe electron pair centers (Sn²⁺/Sn⁴⁺ and Fe²⁺/Fe³⁺) through loading the electron donor Pt (Pt/SFO-1, -2, -3, -4). Experimental and theoretical calculations indicate that abundant dynamic active centers can facilitate the production of reactive oxygen species (ROS), which enables Pt/SFO samples to possess catalase (CAT), peroxidase (POD), and oxidase (OXD) enzyme-like activities. Upon near-infrared (NIR) laser irradiation, Pt/SFO-2 with a Pt load of 0.9% achieves the highest ROS production, showing a 9-fold compared with SnFe₂O₄ and implements the synergistic therapy of photothermal therapy (PTT), photodynamic therapy (PDT), and chemodynamic therapy (CDT). The electronic state regulation of inorganic photothermal agents not only improves tumor therapeutic effects but also offers a novel strategy to regulate the electron structure of active centers.