Ultrasound Research Today is a free monthly online journal that collates and summarizes the latest research about Ultrasound, including details on screening, diagnosis, pregnancy, detection.

Study of sonoporation dynamics affected by ultrasound duty cycle.

Pan H, Zhou Y, Izadnegahdar O, Cui J, Deng CX

Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 44106-7207, USA.

Sonoporation is the ultrasound-induced membrane porosity and has been investigated as a means for intracellular drug delivery and nonviral gene transfection. The dynamic characteristics of sonoporation, such as formation, duration and resealing of the pores in the cell membrane, determine the process of intracellular uptake of molecules or agents of interest that are otherwise obstructed by the cell membrane barrier. Sonoporation dynamics is also important for postultrasound cell survival. In this study, we investigated the effects of ultrasound duty cycle on sonoporation dynamics using Xenopus oocyte as a model system. Transducer with a center frequency of 0.96 MHz was used to generate pulsed ultrasound of desired duty cycle (5%, 10% and 15%) at a pulse repetition frequency of 1 Hz and an acoustic pressure of 0.4 MPa in our experiments. Employing voltage clamp techniques, we measured the transmembrane current as the direct result of decreased membrane resistance due to pore formation induced by ultrasound application. We characterized the sonoporation dynamics from these time-resolved recordings of transmembrane current to indicate cell membrane status, including pore formation, extension and resealing. We observed that the transmembrane current amplitude increased with increasing duty cycle, while the recovering process of membrane pores and cell survival rate decreased at higher duty cycles.

Published 6 June 2005 in Ultrasound Med Biol, 31(6): 849-56.
Full-text of this article is available online (may require subscription).

© 2004-2008 Ultrasound Research Today. All Rights Reserved.