Abstract
Transient cell membrane permeabilization by using ultrasound with the aid of microbubbles, i.e., sonoporation, is one of promising techniques for non-invasive drug delivery system. To improve the efficiency of successful sonoporation and the survival fraction of cells after the procedure, various in vitro sonoporation systems have been developed. Here, we report how experimental settings of the Well-on-Water-Surface (WWS) type in vitro sonoporation system affect the survival fraction of cells under sonoporation conditions. By changing the medium height of the cell culture dish by 0.1 mm, we measured the peak pressure amplitude in the dish during exposure to 1 MHz continuous wave ultrasound and counted the number of viable cells before and after exposure to the ultrasound with the aid of 0.1 ml/dish microbubbles SONAZOID[○!R]. Under the experimental condition, the peak pressure amplitude varied in the range from 0.4 to 0.6 MPa, and the survival fraction, the fraction of the number of viable cells after the procedure, from 25 to 85 %, which may be explained by the effects of standing wave in the dish. For the better estimation of sonoporation efficiency in the WWS type sonoporation system, the medium height in the dish should be set carefully.
