Synergistically Enhanced Chemodynamic Therapy Induced by NIR-II Photothermal Therapy with MRI/CT Imaging Guidance for Colorectal Cancer

Chemodynamic therapy (CDT) exhibits unsatisfactory therapeutic efficacy for colorectal cancer (CRC) due to the hyposensitive Fenton reaction. Herein, we constructed a novel multifunctional nanoplatform based on bismuth-doped iron selenide nanoparticles (BFS NPs) for promoting the therapeutic performance of CDT on CRC. BFS NPs can realize CDT and second near-infrared photothermal therapy (NIR-II PTT) by means of the Fenton reaction and an excellent photothermal conversion efficiency (η = 31.9%). Moreover, the rising temperature induced by NIR irradiation accelerates the Fenton reaction rate because of there being more activated H2O2, thereby improving reactive oxygen species (ROS) levels to address the insufficient hydrogen peroxide concentration. The results showed that the combination of CDT with NIR-II PTT significantly inhibits the growth of CRC and minimizes adverse reactions. Meanwhile, bismuth doping endows the BFS NPs with superior CT imaging and T2-weighted magnetic resonance imaging (T2-MRI) capacities. These unique properties offer an appropriate treatment time window for guiding NIR-II PTT. In summary, this nanoplatform improves the therapeutic effect of CDT and accurately regulates NIR-II PTT by MRI/CT imaging guidance, which provides a new perspective for effective and precise therapy of CRC.