Copper-induced synthesis of versatile FeOx nanozymes for catalytic cancer therapy

The recent advancement of nanocatalysis offers great promise for cancer therapy, and the development of efficient nanozymes for catalytic biological reactions is highly desirable, but still challenging. Herein, we report the synthesis of ultra-small FeO x nanozymes which is enabled by the introduction of Cu 2+ . The obtained nanozymes exhibit versatile catalytic activities integratively for effective cancer treatment. In particular, the as-synthesized nanozymes display pH-dependent peroxidase (POD)-like catalytic activity and approach the optimal performance at around pH = 4, endowing it with the possibility for the precise treatment of tumors with acidic microenvironment. Furthermore, the FeO x nanozyme possesses a promising glutathione (GSH) depleting capability and allows to reverse the abnormal GSH level in the tumor issues. Additionally, the fabricated nanozymes are able to catalyze the decomposition of hydrogen peroxide (H 2 O 2 ) to O 2 , allowing to alleviate the hypoxic environment of the tumors and improving the function of immune system for the treatment of tumors. More importantly, the FeO x nanozymes showed remarkable stability and maintained the enzymatic activity after six months in storage. Collectively, the FeO x nanozyme was demonstrated as a promisingly effective nanomedicine for tumor treatment by 4T1 cells, providing insight into the rational design of efficient nanozymes for cancer treatment. Graphical abstract