Manganese Dioxide Coated Piezoelectric Nanosonosensitizer for Cancer Therapy with Tumor Microenvironment Remodeling and Multienzyme-Like Catalysis.

Sonodynamic therapy (SDT) as an emerging method for cancer therapy has encountered difficulty in insufficient production of reactive oxygen species (ROS), especially in tumor microenvironment (TME) with elevated antioxidants and hypoxic conditions. In this work, the authors have fabricated heterostructured manganese dioxide (MnO 2 )-coated BaTiO 3 nanoparticles (BTO@M NPs) as a piezoelectric sonosensitizer, which exhibits the capacity of remodeling TME and multienzyme-like catalysis for boosting SDT. Benefitting from the piezotronic effect, the formation of a p-n junction between MnO 2 and piezoelectric BTO with a built-in electric field and band bending efficiently promotes the separation of charge carriers, facilitating the generation of superoxide anion (•O 2 - ) and hydroxyl radical (•OH) under ultrasound (US) stimulation. Moreover, BTO@M NPs can catalyze the overexpressed hydrogen peroxide (H 2 O 2 ) in TME to produce oxygen for replenishing the gas source in SDT, and also deplete antioxidant glutathione (GSH), realizing TME remodeling. During this process, the reduced Mn(II) can convert H 2 O 2 into •OH, further amplifying cellular oxidative damage. With these combination effects, the versatile BTO@M NPs exhibit prominent cytotoxicity and tumor growth inhibition against 4T1 breast cancer. This work provides a feasible strategy for constructing high-efficiency sonosensitizers for cancer SDT.