Photo- and sono-dynamic therapy: a review of mechanisms and considerations for pharmacological agents used in therapy incorporating light and sound

As irreplaceable energy sources of minimally invasive treatment, light and sound have, separately, laid solid foundations in their clinic applications. Limited by relatively shallow penetration depth of light, traditional therapeutic modality of photodynamic therapy (PDT) usually involves superficial targets such as shallow seated skin conditions, head and neck cancers, eye disorders, early stage cancer of esophagus, etc. For ultrasound-driven sonodynamic therapy (SDT), however, accessibility to various organs is permitted by superior transmission and focusing ability of ultrasound in biological tissues, enabling multiple therapeutic applications including treating glioma, breast cancer, hematologic tumor and opening blood-brain-barrier (BBB), etc. Considering the newly-emerged theranostics and precision therapy, these two classic energy sources and corresponding sensitizers are worth re-evaluating. In this review, three typical therapies using light and sound as trigger, PDT, SDT, and combined PDT and SDT are introduced. The therapeutic dynamics and current designs of pharmacological sensitizers involved in these therapies are presented. By introducing both the history of the field and the most up-to-date design strategies, this review provides a systemic summary on the development of PDT and SDT, and fosters inspiration for researchers working on 'multi-model' therapies involving light and sound.