In vitro sonodynamic cytotoxicity in regulated cavitation conditions.

Sonodynamic toxicity has always been linked to the cavitation phenomenon. In this work, sonodynamic effect with Photofrin was evaluated with a new ultrasound device: a regulated cavitation generator. In this way, acoustic intensity was substituted with cavitation level as ultrasound parameter. Photofrin potentiated significantly the cavitation cytotoxicity even for low setpoints where no inertial cavitation appeared. Therefore sonodynamic mechanism was principally mechanical, facilitated by the Photofrin insertion in cellular cytoplasmic membranes. This assertion was also supported by the fact that sonodynamic cytotoxicity was independent from the Photofrin presence or absence in the extracellular medium. Reproducible sonodynamic efficiency was perfectly obtained with this new regulated cavitation generator.