Nanocatalytic Theranostics with Glutathione Depletion and Enhanced Reactive Oxygen Species Generation for Efficient Cancer Therapy.

Abstract

Chemodynamic therapy (CDT) is an emerging therapy method that kills cancer cells by converting intracellular hydrogen peroxide (H₂ O₂ ) into highly toxic hydroxyl radicals (^• OH). To overcome the current limitations of the insufficient endogenous H₂ O₂ and the high concentration of glutathione (GSH) in tumor cells, an intelligent nanocatalytic theranostics (denoted as PGC-DOX) that possesses both H₂ O₂ self-supply and GSH-elimination properties for efficient cancer therapy is presented. This nanoplatform is constructed by a facile one-step biomineralization method using poly(ethylene glycol)-modified glucose oxidase (GOx) as a template to form biodegradable copper-doped calcium phosphate nanoparticles, followed by the loading of doxorubicin (DOX). As an enzyme catalyst, GOx can effectively catalyze intracellular glucose to generate H₂ O₂ , which not only starves the tumor cells, but also supplies H₂ O₂ for subsequent Fenton-like reaction. Meanwhile, the redox reaction between the released Cu²⁺ ions and intracellular GSH will induce GSH depletion and reduce Cu²⁺ to Fenton agent Cu⁺ ions, and then trigger the H₂ O₂ to generate ^• OH by a Cu⁺ -mediated Fenton-like reaction, resulting in enhanced CDT efficacy. The integration of GOx-mediated starvation therapy, H₂ O₂ self-supply and GSH-elimination enhanced CDT, and DOX-induced chemotherapy, endow the PGC-DOX with effective tumor growth inhibition with minimal side effects in vivo.