Efficient generation of reactive oxygen species sonochemically generated by cavitation bubbles

Background: Sonodynamic treatment is a cancer treatment method using by cavitation bubbles generated by ultrasound. In sonodynamic treatment, generating ROS efficiently by cavitation bubbles at target cancerous tissue is important. Objective: The aim of this paper is generating ROS efficiently by using exposure sequence which have short, high-intensity ultrasound pulse (triggered pulse) immediate followed by long, moderately low-intensity ultrasound burst (sustaining waves). Experiment: Cavitation bubbles were generated by using two sequences. The firsts sequence had both of triggered pulse and sustaining waves. The second one had only triggered pulse. After ultrasound exposure finished, the amount of ROS was quantified by KI method. Result and conclusion: The sequence which had both trigger pulse and sustaining waves generated ROS more efficient than the sequence which had only triggered pulse. The reason of this result is that sustaining waves oscillated cavitation bubbles volumetrically which were generated by triggered pulse and such volume oscillation of bubbles by sustaining waves contributes for efficient generation of ROS.