Tumor acidification and GSH depletion by bimetallic composite nanoparticles for enhanced chemodynamic therapy of TNBC.

Chemodynamic therapy (CDT) based on intracellular Fenton reaction to produce highly cytotoxic reactive oxygen species (ROS) has played an essential role in tumor therapy. However, this therapy still needs to be improved by weakly acidic pH and over-expression of glutathione (GSH) in tumor microenvironment (TEM), which hinders its future application. Herein, we reported a multifunctional bimetallic composite nanoparticle MnO@GA-Fe@CAI based on a metal polyphenol network (MPN) structure, which could reduce intracellular pH and endogenous GSH by remodeling tumor microenvironment to improve Fenton activity. MnO nanoparticles were prepared first and MnO@GA-Fe nanoparticles with Fe as central ion and gallic acid (GA) as surface ligands were prepared by the chelation reaction. Then, carbonic anhydrase inhibitor (CAI) was coupled with GA to form MnO@GA-Fe@CAI. The properties of the bimetallic composite nanoparticles were studied, and the results showed that CAI could reduce intracellular pH. At the same time, MnO could deplete intracellular GSH and produce Mn via redox reactions, which re-established the TME with low pH and GSH. In addition, GA reduced Fe to Fe. Mn and Fe catalyzed the endogenous HO to produce high-lever ROS to kill tumor cells. Compared with MnO, MnO@GA-Fe@CAI could reduce the tumor weight and volume for the xenograft MDA-MB-231 tumor-bearing mice and the final tumor inhibition rate of 58.09 ± 5.77%, showing the improved therapeutic effect as well as the biological safety. Therefore, this study achieved the high-efficiency CDT effect catalyzed by bimetallic through reshaping the tumor microenvironment.