The Ultrasound effects on non tumoral cell line at 1 MHz therapeutic frequency

The aim of this research is to investigate some bioeffects due to Therapeutic Ultrasound (1 MHz and 50<IPA<60 W/cm2) which could allow to enhance drugs or genes delivery in non tumoral cells [1]. Ultrasound (US) has been demonstrated to alter the cell membrane permeability due to a biophysical mechanism, Sonoporation, and exploited as a promising non-invasive gene transfer method. We have used the NIH-3T3 cell line as a model system and exposed it to US medical equipment for 15, 30, 45, 60 minutes at distances of 10 and 15 cm from the source transducer, corresponding to the far field region where 0.4 4.0 42> = = ±?az zlast cm. We have worked with the maximum power in pulsed system with 75% duty cycle. Characterization of the unfocused, planar and with a circular geometry 1 MHz source transducer, was performed and the acoustics pressure was measured by a calibrated 0.5 mm needle hydrophone; moreover, the pressure field generated by the source transducer was simulated. The US effects on cells were assessed by Fourier transform infrared (FTIR) Imaging with focal plane array (FPA) detector. By the IR analysis, the US exposure on non tumoral cells has induced a change of the intensity for CH2 asymmetric stretching (2924 cm-1) band in the lipid region (3000-2800 cm-1) that it could detect an energy-dependent process. It has already shown that cells invest energy to catalyze lipid movement in order to maintain a specific transmembrane phospholipid distribution. Although asymmetry is the rule for control cells, the loss of asymmetry could be associated with the permeability change of plasma membrane inducing temporary pores