The influence of congelation and gamma-irradiation on cord blood serum through the data of VHF-dielectrometry

Abstract

Influence of freezing to -196°C and subsequent gamma-irradiation with doses 20, 50, 100, and 150 Gy on human cord blood serum by method VHF-dielectrometry have been studied in this work. Cord blood serum was frozen at the rate of 300 400°C/min to the temperature of -196°С by immersing it in liquid nitrogen. Native specimens and specimens after freezing-thaw were irradiated at room temperature in an air atmosphere with gamma - rays source Co⁶⁰. Measurement of the real part of frozen, irradiated, and subsequently frozen and irradiated serum specimens complex permittivity ε' was done by the cavity method on frequency 9,3 GHz at room temperature (20°С). As the results of the investigation done freezing of cord blood serum to -196°C was lead to the result of the increase of permittivity what may be serum proteins cryoaggregation. On the contrary, gamma-irradiation leads to decrease cord blood serum permittivity. Decrease of dielectric parameters of serum after irradiation is assumed to be due to conformational changes in its proteins connected with break-in intramolecular hydrogen bonds, loosening in macromolecules surface and increasing amount of hydration water owing to the formation of new hydrogen bonds with volume water molecules. Magnitudes of the real part of complex permittivity ε' of the cord blood after freezing to 196°C and subsequent gamma-irradiation have lower values than those just after freezing but higher than those only after gamma-irradiation. It justifies to the additive contribution of these physical factors in the magnitude of permittivity of the cord blood serum. Diversities of these magnitudes of permittivity of the serum after freezing and serum after subsequent action of freezing and gamma-irradiation are coincide within the limits of error and are independent of the dose of irradiation showing independent nature of the action of low temperatures and irradiation with doses up to 150 Gy on properties of cord blood serum.