Recent exploration of inorganic sonosensitizers for sonodynamic therapy of tumors

With the rapid development of nanomedicine and nanobiotechnology, various therapeutic methods have been applied with good efficacy and biological safety. As a non-invasive treatment method, sonodynamic therapy (SDT) can effectively treat deep tumors with less damage to the surrounding tissue and high adaptability. The ultrasound sensitizer is an indispensable and important part of the SDT process, and its structure and properties directly determine the therapeutic effect of SDT. Compared with conventional organic sonosensitizers, inorganic sonosensitizers including noble metal-based, transition metal-based, silicon-based and carbon-based sonosensitizers have high stability, controllable morphology and long circulation time in the human body, which has greatly expanded their research applications in SDT. In this review, the possible mechanisms of SDT, i.e. the cavitation effect and the generation of reactive oxygen species, are briefly discussed. Subsequently, recent research progress of inorganic sonosensitizers is systematically summarized in terms of their formulations and antitumor effects with a focus on strategies to optimize therapeutic efficacy. The current challenges and future are presented to provide insights into strengthening the interdisciplinary collaborations so as to promote the innovation and development of SDT technology in clinical application.