引入细胞内冰晶体积项至经典的Mazur方程,将其适用范围拓宽至可用于描述整个冷冻过程中透过细胞膜的水输运.通过耦合改进后的Mazur方程、冰晶成核、扩散控制的晶体生长理论,建立新的胞内冰晶成核与生长的模型.新模型不受低温保护剂浓度的限制,可正确预测细胞内冰晶成核、生长、最终体积份额、冰晶大小分布等关键信息.使用新模型详细研究了甘油初始浓度、降温速率等因素对于冷冻过程中细胞体积变化、胞内溶液冰晶成核和生长过程,以及最终胞内冰晶体积份额等的影响.结果表明:低温保护剂的存在可有效缓解细胞的失水过程,减少细胞内冰晶的体积份额;对特定的初始低温保护剂浓度,存在最佳降温速率对应最小细胞内冰晶体积份额.
The classical water transport model developed by Mazur was extended to be capable of predicting cell volumetric change even after intracellular ice formation (IIF). By coupling the modified Mazur model, ice nucleation, and the diffusion-limited ice growth theory, the new model describing IIF and the growth of the intracellular ice (IIG) was developed based on Karlsson's work in 1994. The new model could be used to predict IIF, IIG, the final volumetric fraction of the intracellular ice without the limitation of initial cryoprotective agent (CPA) concentration. The model was then used to study the effect of cooling rate and initial CPA concentration on IIF and IIG. It was found that i) the presence of CPA could markedly slow down IIG and decrease the final volume of intracellular ice, and ii) there exists the optimal cooling rate with minimal final volume of intracellular ice corresponding to certain initial CPA and its concentration.