Sonodynamic Therapy with Metal Complexes: A New Promise in Cancer Therapy

Abstract

In recent years, to overcome the problem of low tissue penetration power of light in photodynamic therapy (PDT), sonodynamic therapy (SDT) with ultrasound (US) as the drug stimulus has emerged as a potential alternative to PDT. The significantly higher tissue penetration capacity of US is reported to allow the treatment of deep‐seated tumours. In general, organic molecules and nanomaterials dominate as the sonosensitizers in this area of research, and the potential of metal complexes in SDT is not yet well explored. In this highlight, we have summarized two recent literature reports in which researchers have explored the efficiency of metal complexes as sonosensitizers for the first time. These reports indicate the high potential of metal complexes in SDT.

Newly developed gas-assisted sonodynamic therapy in cancer treatment

“…Integrating SDT with gas therapy has attracted considerable attention as a suitable treatment modality for cancer on account of the combination of the noninvasiveness and high penetration of US and with high efficacy and biosafety of gases 102 , 103 , 104 . Based on the supportive exploratory findings, gas-assisted therapy can synergistically enhance the effects of SDT primarily through the following mechanisms.…”

Facile synthesis of a hydrazone-based zinc(ii) complex for ferroptosis-augmented sonodynamic therapy

“…Some of them are mainly derived from traditional photosensitizers, such as organic small molecule chlorin e6 (Ce6) and transition metal complex tripyridinium ruthenium ([Ru(bpy) 3 ] 2+ ), which can exhibit both photodynamic and sonodynamic activities. 5a,22 Among them, transition metal complexes could exhibit superiority in the aspect of photodynamic or sonodynamic performance than that of organic small molecules due to the heavy atom effect, 23,24 but their potential physiological toxicity limits their further clinical applications.…”

Nanomaterial-based sonosensitizers: from exemplary design towards purposeful improvement

“…Sonodynamic therapy (SDT), which is conceptually similar to photodynamic therapy (PDT), has attracted great attention in tumor therapy since its emergence. 1 In comparison with conventional therapies (surgery, radiotherapy and chemodynamic therapy (CDT)) with low relevance, high recurrence rate and unignorable damage to normal tissues, SDT showed satisfactory effects especially when facing malignant tumors with a high recurrence rate. 2 For PDT, which used light to activate photosensitizers (PSs) and generated cytotoxic reactive oxygen species (ROS), it was limited by the penetration depth of the light, and the penetration depth of near-infrared-II (NIR-II) fluorescence was approximately equal to 8 mm, which was still unsuitable for deep tumor therapy.…”