Nanoparticle-assisted ultrasound: A special focus on sonodynamic therapy against cancer

TLDR

Ultrasound is widely used in medicine for diagnosis and therapy, and its interaction with nanoparticles during acoustic cavitation involves complex, synergistic physical‑chemical processes. This review examines therapeutically active nanoparticles stimulated by ultrasound, focusing on sonodynamic therapy and the debated mechanisms of NP‑assisted treatments. The authors outline ultrasound‑based oncologic techniques, describe various nanoparticle types (liposomes, micro/nano‑bubbles, metal and metal‑oxide NPs), and explain how NP structure and interaction with ultrasonic pressure waves drive cancer cell death. Clinical applications of NP‑assisted ultrasound are summarized, highlighting its innovative potential yet noting that it remains in the early stages of clinical cancer treatment.

Abstract

At present, ultrasound radiation is broadly employed in medicine for both diagnostic and therapeutic purposes at various frequencies and intensities. In this review article, we focus on therapeutically-active nanoparticles (NPs) when stimulated by ultrasound. We first introduce the different ultrasound-based therapies with special attention to the techniques involved in the oncological field, then we summarize the different NPs used, ranging from soft materials, like liposomes or micro/nano-bubbles, to metal and metal oxide NPs. We therefore focus on the sonodynamic therapy and on the possible working mechanisms under debate of NPs-assisted sonodynamic treatments. We support the idea that various, complex and synergistics physical-chemical processes take place during acoustic cavitation and NP activation. Different mechanisms are therefore responsible for the final cancer cell death and strongly depends not only on the type and structure of NPs or nanocarriers, but also on the way they interact with the ultrasonic pressure waves. We conclude with a brief overview of the clinical applications of the various ultrasound therapies and the related use of NPs-assisted ultrasound in clinics, showing that this very innovative and promising approach is however still at its infancy in the clinical cancer treatment.