School of Electronic Information Engineering, Internet of Things and Big Data Research Center, Xijing University, Xi'an, China.
Biopreserv Biobank. 2021 Feb;19(1):19-26. doi: 10.1089/bio.2020.0045. Epub 2020 Oct 16.
Cryopreservation, which refers to preservation of cells or tissues at subzero temperatures, inevitably involves the problem of cryoinjury caused by ice crystals. The application of an external electric field during the freezing process has been shown to be a promising approach to produce miniature ice grains and decrease the fraction of ice crystallization at a slow cooling rate. Thus, the dielectric and thermodynamic properties of NaCl-HO binary solutions at subzero temperatures were tremendously important for understanding the mechanism of ice formation under the manipulation of an AC electric field in biopreservation. However, there was still a lack of relevant information in the literature. The first objective of this study was to systematically measure the dielectric spectrum of 0.9% NaCl-HO binary solutions at temperatures ranging from -100°C to 0°C with a cooling/heating rate of 2°C/min. We further measured the thermodynamic properties of a 0.9% NaCl-HO binary solution while applying a series of electric fields near its dielectric relaxation frequency. The effect of the electric field on the crystal morphology was studied last. Pure water was selected as the control group. The results showed that an AC electric field can alter the thermodynamic process and thus the phase transition and ice crystal structure could be manipulated. It was concluded that the AC electric-assistant preservation method will be a promising technology in cryopreservation.
冷冻保存是指将细胞或组织保存在低温下，不可避免地会涉及到由冰晶引起的冷冻损伤问题。在冷冻过程中施加外电场已被证明是一种很有前途的方法，可以产生微小的冰晶，并在缓慢冷却速率下减少冰晶形成的比例。因此，了解在交流电场作用下生物保存过程中冰形成的机制，需要对 NaCl-H2O 二元溶液在低温下的介电和热力学性质有深入的认识。然而，文献中仍然缺乏相关信息。本研究的首要目标是系统地测量在冷却/加热速率为 2°C/min 的情况下，温度范围从-100°C 到 0°C 的 0.9%NaCl-H2O 二元溶液的介电谱。我们进一步测量了在接近其介电弛豫频率的一系列电场下 0.9%NaCl-H2O 二元溶液的热力学性质。最后研究了电场对晶体形态的影响。选择纯水作为对照组。结果表明，交流电场可以改变热力学过程，从而可以操纵相变和冰晶结构。结论是，交流电场辅助保存方法将是冷冻保存中一种很有前途的技术。
