Two-dimensional silicene composite nanosheets enable exogenous/endogenous-responsive and synergistic hyperthermia-augmented catalytic tumor theranostics

Silicene as an emerging two-dimensional material (2DM) spurs the broad research interests due to its prominent electronic and physical properties, however, still lacking in exploitation for the biological and medical practices. Herein, we constructed a 2D silicene-based theranostic nanoplatform, MnOx@silicene-BSA (MS-BSA), with tumor microenvironment (TME)-responsive and synergistic hyperthermia-augmented catalytic activity when irradiated by near infrared-II (NIR-II) laser because of the high photothermal-conversion efficiency of 2D silicene matrix. Such MS-BSA nanosheets possess the capability to react with glutathione (GSH) to generate Mn2+ and glutathione disulfide (GSSG) under acidity/reducing TME condition. With the presence/assistance of HCO3-, the released Mn2+ exhibited sensitive catalytic activity towards endogenous H2O2 via Fenton-like reaction, enabling the generation of highly toxic hydroxyl radicals (center dot OH), which finally led to the enhanced nanocatalytic therapeutic efficacy followed by exogenous NIR-II laser exposure, originating from hyperthermia-augmented catalytic activity. Especially, these MS-BSA nanosheets accumulated into the tumor region to enable superb contrast enhancement of TME-responsive T-1-weighted magnetic resonance imaging (MRI) and photoacoustic imaging (PAI), and high-efficient in vivo synergistic tumor eradication. Therefore, such an intelligent photothermal-enhanced catalytic theranostic nanoplatform could realize the exogenous/endogenous-responsive and cooperative hyperthermia-augmented tumor treatment and accurate tumor positioning/monitoring.