X-ray-facilitated redox cycling of nanozyme possessing peroxidase-mimicking activity for reactive oxygen species-enhanced cancer therapy

Nanomaterials with shifting or mixed redox states is one of the most common studied nanozyme with peroxidase-like activity for chemodynamic therapy (CDT), which can decompose hydrogen peroxide (H 2 O 2 ) of tumor microenvironment into highly toxic reactive oxygen species (ROS) by a nano-catalytic way. However, most of them exhibit an insufficient catalytic efficiency due to their dependence on catalytic condition. Herein, a potential methodology is proposed to enhance their enzymatic activity by accelerating the redox cycling of these nanomaterials with shifting or mixed redox states in the presence of X-ray. In this study, the nanocomposite consisting of SnS 2 nanoplates and Fe 3 O 4 quantum dots with shifting or mixed redox states (Fe 2+ /Fe 3+ ) is used to explore the strategy. Under external X-ray irradiation, SnS 2 cofactor as electron donor can be triggered to transfer electrons to Fe 3 O 4 , which promotes the regeneration of Fe 2+ sites on the surface of the Fe 3 O 4 . Consequently, the regenerated Fe 2+ sites react with the overexpressed H 2 O 2 to persistently generate ROS for enhanced tumor therapy. The designed nanocomposite displays the synergistic effects of radiotherapy and CDT. The strategy provides a new avenue for the development of artificial nanozymes with shifting or mixed redox states in precise cancer treatments based on X-ray-enhanced enzymatic efficacy.