Investigating the contributions of ultrasonic cavitation in skin permeability enhancement

Sonophoresis uses low-frequency ultrasound (US) to enhance transdermal drug delivery through acoustic cavitation bubbles formed in the coupling medium applied to the skin for US transmission, creating localised permeable regions on the skin for drug transport. To address the poor coverage of permeable regions on the treated skin, which limits drug delivery at clinically relevant doses, we propose to visualise the cavitation dynamics in different hydrogel-based coupling media and to correlate it to the resulting skin permeability assessed in terms of superficial skin damage. Experiments will be conducted on animal-derived biological skin samples using ultrafast X-ray phase contrast imaging and microtomography. The results will elucidate the key physical mechanism underlying sonophoresis-based drug delivery and reveal how different coupling medium compositions affect the efficacy of sonophoresis treatments, identifying the most effective one.