Effects induced in cells by ultrasound revealed by ATR-FTIR spectroscopy

In this study we have used for the first time the infrared spectroscopy as a tool to reveal the effects induced on a cell line, Jurkat T-lymphocytes, by ultrasound (US) used in therapy at 1 MHz frequency. We carried out the experiments using two different setups allowing to change the acoustic field parameters by varying the position of the sample with respect to the ultrasonic transducer and the sonication time with different duty cycles. The parameters of acoustic field measured by a hydrophone were compatible with the cavitation phenomenon in both setups. Genotoxic damage in exposed cells was ascertained by the cytokinesis-block micronucleus (CBMN) assay whilst cell structural changes due to sonication, were revealed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, a non-destructive technique that allows, by the acquisition of IR spectra within a few minutes, one to obtain simultaneous information on all cellular macromolecules in a cell population. Infrared spectroscopy results highlight changes of functional groups typical of proteins, nucleic acids and lipids at 118 J/cm 2 energy dose, while the micronuclei test shows no toxic damage to the cellular samples; higher energy doses are necessary to reveal significant toxic effects together with structural changes.