A cascade reaction nanoplatform with magnetic resonance imaging capability for combined photothermal/chemodynamic/gas cancer therapy

To effectively exploit the tumor microenvironment (TME), TME-responsive nanocarriers based on cascade reactions have received much attention. In this study, we designed a novel nanoparticle PB@SiO₂@MnO₂@P-Arg (PMP) to construct a cascade reaction nanoplatform. While using biosafety Prussian blue (PB) for photothermal therapy (PTT), this nanoplatform uses silica (SiO₂) as an intermediate layer to assemble Prussian blue and manganese dioxide (MnO₂) into a core-shell structure, which effectively enhances the response of the nanoplatform to TME and promotes the effect of chemodynamic therapy (CDT) resulting from glutathione (GSH) depletion and Fenton-like reaction. The released Mn²⁺ can also be used for magnetic resonance imaging (MRI). Through the cascade reaction, poly-l-arginine (P-Arg) coated on the surface of the nanoparticles can react with hydroxyl radical (•OH) obtained from the Fenton-like reaction to release nitric oxide (NO), which further reacts with O₂•^- to produce the more toxic peroxynitrite anion (ONOO^-). The photothermal effect of PB further enhances the effect of the cascade reaction while reducing the amount of heat required for treatment. <i>In vitro</i> and <i>in vivo</i> studies confirmed the antitumor effects of cascade reaction-based nanoplatforms in combined photothermal/chemodynamic/gas cancer therapies, providing new strategies for the design and fabrication of multifunctional nanoplatforms that integrate diagnostic and therapeutic functions, as well as the application of cascade reactions in multimodal synergistic therapy.