Qualitative evaluation of human serum proteins accelerated ageing after neutron radiation exposure by differential scanning calorimetry

Abstract Introduction Among biological macromolecules, proteins are increasingly recognised as key radiation targets. Conformational modifications of proteins and their stability after exposure to ionising radiation are fundamental issues in radiobiology and radiotherapy. This study aimed to qualitatively assess the accelerated ageing of human serum proteins after in vitro exposure to neutron radiation using differential scanning calorimetry (DSC). Material and methods Human serum samples from healthy volunteers were exposed to a 5 Gy dose of neutron radiation. The Californ-252 was utilised as the radiation source, with activity ranging from 65 to 58 MBq and an average neutron energy of 2.35 MeV. DSC profiles were acquired for fresh, control, and irradiated serum samples immediately after exposure. Subsequent DSC measurements were conducted weekly for one month. Results A qualitative analysis of DSC profiles made it possible to assess alterations in the serum proteins’ denaturation processes over time. The appearance of a low-temperature exothermic transition before the endothermic transition appears to be a characteristic feature of ageing-altered DSC serum profiles. All the changes visible on the DSC profiles of the irradiated samples are much more advanced than on the profiles of the control samples. In addition, the DSC method made it possible to observe the effect of individual variability on the shape of the DSC serum profiles of particular volunteers. Conclusions The study revealed that neutron irradiation most likely accelerates serum protein ageing processes. The results indicate a considerable variation in individual radiosensitivity of proteins taken from individuals to the effect of neutron radiation. In the future, the DSC measurement could be a simple test that provides information on the magnitude of personal radiosensitivity, an interesting aspect in the context of personalised radiotherapy.