Precise Design of TiO 2 @CoO x Heterostructure via Atomic Layer Deposition for Synergistic Sono-Chemodynamic Oncotherapy.

Sonodynamic therapy (SDT), a tumor treatment modality with high tissue penetration and low side effects, is able to selectively kill tumor cells by producing cytotoxic reactive oxygen species (ROS) with ultrasound-triggered sonosensitizers. N-type inorganic semiconductor TiO ₂ has low ROS quantum yields under ultrasound irradiation and inadequate anti-tumor activity. Herein, by using atomic layer deposition (ALD) to create a heterojunction between porous TiO ₂ and CoO _x , the sonodynamic therapy efficiency of TiO ₂ can be improved. Compared to conventional techniques, the high controllability of ALD allows for the delicate loading of CoO _x nanoparticles into TiO ₂ pores, resulting in the precise tuning of the interfaces and energy band structures and ultimately optimal SDT properties. In addition, CoO _x exhibits a cascade of H ₂ O ₂ →O ₂ →·O ₂ ^- in response to the tumor microenvironment, which not only mitigates hypoxia during the SDT process, but also contributes to the effect of chemodynamic therapy (CDT). Correspondingly, the synergistic CDT/SDT treatment is successful in inhibiting tumor growth. Thus, ALD provides new avenues for catalytic tumor therapy and other pharmaceutical applications.
(© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)