Intracellular and extracellular ion variation measurement in alpha(α)-particle irradiated cells using t-FROZEN! and laser-induced breakdown spectroscopy

Many radiobiological changes occur in unirradiated cells due to concealed signals transmitted from the irradiated cells through the Radiation-induced bystander effect (RIBE). Calcium ions (Ca2+) remain the only ion–molecule extensively studied so far amongst the ions that control cell function. This is partly due to using fluorescent indicators to investigate the signaling process that suffers limitations in labelling procedure and ion specificity. To understand the ion imbalance in irradiated cells and cell medium serving as donor and carrier of the bystander signals. Here, we investigate ion concentrations in the extracellular and intracellular space of α-particle (Am-241) irradiated Chinese hamster ovary (CHO) cells exposed to two different radiation doses (0.3 nGy, and 0.7 nGy). Laser-induced breakdown spectroscopy (LIBS) with our novel t-FROZEN! method separating the cells from its extracellular matrix was employed as a tool. Also, X-ray fluorescence spectroscopy (XRF), inductively coupled plasma-optical emission spectrometry (ICP-OES), and electrical impedance measurements were employed as complementary techniques. Our results show that influx of K+ and outflux of Na+, Mg2+, Cl- and Ca2+ occur in the irradiated cells, compared with controls, leading to an imbalance in the concentration of crucial signaling ions across the cell membrane. Our study has provided vital insights into comprehensive composition of ion-based radiation-induced bystander signals and guide the development of Na+, Mg2+, Cl- and K+ channel targeting drugs.