Effects of low-dose gamma radiation on DNA measured using a quartz tuning fork sensor

Despite the expected direct effects of radiation on DNA through its direct interaction with the biomolecule, research indicates that radiation also interacts with the DNA's environment, resulting in indirect effects. Therefore, in this study, we explored the feasibility of using the quartz tuning fork (QTF) sensor system in biomedical applications, specifically in detecting DNA damage caused by low doses of gamma radiation, directly and indirectly. We differentiated between direct and indirect damage by analyzing the fork's resonance frequency changes. This experiment was divided into three stages: before, during, and after irradiation. Each stage involved samples of pure DNA and DNA in a 60-mu L aqueous solution, evaluated under identical conditions. Before irradiation, we measured frequency shifts (Delta f) over a 20-min period, resulting in values of 19.34, 20.25, and 7.6 Hz for water, DNA, and DNA in water, respectively. Subsequently, the samples were irradiated with cesium-137 for the specified duration, resulting in frequency shifts of 39.21, 28.37, and 41.23 Hz for the same conditions. Our investigations showed an increase in Delta f from 20.25 to 28.3 Hz at doses ranging from 7.5 to 30 mu Gy for pure DNA. Interestingly, DNA in aqueous solution exhibited hypersensitivity to radiation, with frequency shifts ranging from 7.6 to 41.23 Hz. Furthermore, we observed a significant difference in frequency shift after irradiation between pure DNA and DNA in water, with shifts of 70.75-98.45 Hz and 56.32-79.28 Hz for DNA and DNA in water, respectively. This result indicates a significant increase in DNA damage in aqueous environments, driven by the generation of active hydroxyl radicals (OH-), resulting in base damage and an associated increase in strand breaks. Consequently, our research indicates a lack of substantial direct impact on DNA repair owing to the absence of a conducive postirradiation environment. Therefore, QTF is a valuable biomarker for radiation sensitivity and is promising for future applications as a mass-sensitive biosensor.