A chemodynamic nanoenzyme with highly efficient Fenton reaction for cancer therapy.

Chemodynamic therapy (CDT) is a rising technology for cancer therapy by converting intracellular hydrogen peroxide (H2O2) into hydroxyl radical (•OH) via transition-metal-containing nanoparticles (NPs) catalysis reaction (i.e., Fenton reaction) to kill tumor cells. Highly efficient Fenton reaction and favorable delivery of the catalytic NPs "nanoenzyme" are the key for successful treatment of cancer. In this work, we developed a novel nanoenzyme MnFe2O4@GFP for in vitro and in vivo antitumor therapy. A new MnFe2O4 nanoparticle containing two transition-metal-element Fe and Mn was synthesized for elevated Fenton reaction, and further post-processed with dopamine polymerization, green fluorescent protein (GFP) adsorption and PEG coating for model-protein loading and enhanced biocompatibility. The over-expressed H2O2 and glutathione (GSH) in tumor tissue provided a feasible microenvironment for in situ generation of toxic free radicals. Fe3+ and GSH triggered a redox reaction to produce Fe2+, which in turn catalyzed H2O2 into •OH, while the antioxidant GSH was consumed. By introducing another catalyzer Mn2+, the catalytic efficiency of the nanoenzyme were greatly improved. Consequently, the nanoenzyme showed efficient tumor cell killing ability and good inhibiton effect of C6 xenografted glioma in mice. Moreover, the loaded GFP not only acted as a model of protein cargo but also played as a fluorescent indicator of the nanodrug, showing greating potential for future antitumor therapy of the nanosystem.