A new approach to studying the effects of ionising radiation on single cells using FTIR synchrotron microspectroscopy

The effect of ionizing radiation on single cells using a proton source was investigated using Fourier transform infrared (FTIR) microspectroscopy. The prostate cancer cells (DU-145) were irradiated by a specific number (50, 200, 400, 2000 and 4000) of protons per cell. Next after fixing the cells with 70% ethanol micro-FTIR spectra were obtained using both: (a) the synchrotron radiation source with a Mercury–Cadmium–Telluride (MCT) detector and (b) a globar source with a focal plane array (FPA) detector. FTIR spectra obtained from both instrumental configurations were analyzed independently to investigate the changes in the DNA phosphodiester region (1150–950 cm−1) of irradiated and control (untreated by ionizing radiation) cells. A Principal Component Analysis (PCA) scores plot revealed distinct clusters for all groups of irradiated cells, even for those irradiated by the smallest dose of protons. The dose-dependent changes in the relative intensities of DNA peak at 970 cm−1 (ribose-phosphate skeletal motions), along with a shift of the O–P–O band corresponding to the symmetric phosphodiester stretching mode at 1090 cm−1 were observed. The results demonstrate that FTIR spectroscopy is a promising tool to investigate DNA damage in single cells and may become an important tool in assessing cell damage following radiotherapy. - Highlights: • Prostate cancer cells derived from brain metastasis (DU-145 cell line) were used as a model. • Single cells were irradiated with a controlled number (20–4000) of 1 MeV protons from the Cracow microbe. • After fixation, irradiated and control cells were investigated using FTIR microspectroscopy. • Quantitative and qualitative changes in phosphodiester region associated with DNA radiation damage, were observed