Rapid Decomposition and Catalytic Cascade Nanoplatforms Based on Enzymes and Mn-Etched Dendritic Mesoporous Silicon for MRI-Guided Synergistic Therapy.

The endogenous tumor microenvironment (TME) can signally influence the therapeutic effects of cancer, so it is necessary to explore effective synergistic therapeutic strategies based on changing of the TME. Here, a catalytic cascade nanoplatform based on manganese (Mn)-etched dendritic mesoporous silicon nanoparticles (designated as DMMnSiO NPs) loaded with indocyanine green (ICG) and natural glucose oxidase (GOD) is established (designated as DIG nanocomposites). As the Mn-O bonds in DMMnSiO NPs are susceptive to mildly acidic and reducing environments, the DIG nanocomposites can be rapidly decomposed because of the biodegradation of DMMnSiO NPs once internalized into the tumor by the consumption of glutathione (GSH) in TME to weaken the antioxidant capability of the tumors. The released Mn could catalyze endogenous hydrogen peroxide (HO) to generate oxygen (O) to relieve the hypoxia in TME. The generation of O may promote the catalyzed oxidation of glucose by GOD, which will cut off nutrient supplies, accompanied by the regeneration of HO. The regenerated HO could be sequentially catalyzed by Mn to compensate for the consumed O, and thus, the catalytic cascade process between Mn and GOD was set up. As a result, a synergistic therapeutic strategy based on -weighted magnetic resonance imaging (MRI) of Mn, starvation therapy by O-compensation enhanced catalyzing glucose, dual-model (GSH consumption and O compensation) enhanced photodynamic therapy, and effective photothermal therapy of ICG (η = 23.8%) under 808 nm laser irradiation has been successfully established.