Specific-Tuning Band Structure in Hetero-Semiconductor Nanorods to Match with Reduction of Oxygen Molecules for Low-Intensity Yet Highly Effective Sonodynamic/Hole Therapy of Tumors

Abstract

Sonosensitizers-assisted sonodynamic therapy (SDT) has been emerging as a promising treatment for cancers, and yet few specific regulations of band structure of sonosensitizers have been reported in relation to oxygen in tissues. Herein, by a gradient doping technique to modulate the band structure of hetero-semiconductor nanorods, it is found that the reduction potential of band-edge is very critical to reactive oxygen species (ROS) production under low-intensity ultrasound (US) irradiation and particularly, when aligned with the reduction of oxygen, ROS generation is found to be most significantly enhanced. Withal, US-generated oxidation holes are found to be effective in consuming overexpressed glutathione in tumor lesions, which amplifies cellular oxidative stress and finally induces tumor cell death. Moreover, the intrinsic fluorescence property of semiconductors provides imaging capability to illumine tumor area and guide the SDT process. This study demonstrates that the reduction potential state of sonosensitizers is of crucial importance in ROS generation and the proposed reduction potential-tailored hetero-semiconductor nanorods materialize low-intensity US irradiation yet highly effective SDT and synergetic hole therapy of tumors with imaging guidance and reduced radiation injury.

Keywords: band-edge redox potentials; low intensity ultrasound; semiconductor heterojunctions; sonodynamic therapy; sonosensitizers.