低温保护剂载入关节软骨过程的传质建模

Mass Transport Modeling on Cryoprotectant Permeation into Articular Cartilage

掌握加载过程中软骨组织内部低温保护剂浓度的时空分布特性,这对合理设计加载程序进而成功保存关节软骨至关重要,为此构建描述低温保护剂载入关节软骨过程的扩散传质模型。根据二元扩散热力学模型,将有效扩散系数与无限稀释扩散系数进行关联,活度系数采用UNIFAC模型估算,扩散系数的浓度依赖性采用Vignes公式表示,无限稀释扩散系数采用Siddiqi-Lucas公式计算。对于二甲亚砜(Me2SO)、甘油(GLY)、乙二醇(EG)和丙二醇(PG)这4种典型的低温保护剂(CPA),由模型计算得到的软骨组织内CPA的平均浓度与文献报道的实验值之间的平均相对偏差(MRE)和决定系数(R2)分别为1.90%~36.29%和0.959~0.998(Me2SO),13.56%~19.19%和0.990~0.995(GLY),8.89%~22.09%和0.969~0.988(EG),5.35%~23.76%和0.971~0.992(PG)。结果表明,该模型能较好地适用于这4种CPA,可用于直接预测加载过程中软骨组织内部CPA浓度的时空分布,从而指导加载程序的设计与优化。

The knowledge of permeation kinetics of cryoprotective agent（ CPA） in articular cartilage（ AC） is of critical importance for designing optimal CPA addition protocols to achieve successful cryopreservation of AC.In this study,a mass transport model was developed for predicting CPA diffusion in AC. The effective diffusion coefficient was correlated to the infinite dilution coefficients through a binary diffusion thermodynamic model.The UNIFAC model was used to evaluate the activity coefficient,the Vignes equation was employed to estimate the composition dependence of the diffusion coefficient,and the Siddiqi-Lucas correlation was applied to determine the diffusion coefficient at infinite dilution. The model was demonstrated to predict the spatial and temporal CPA distribution in AC during addition. Results showed that the predicted overall CPA uptakes by AC match the experiment data well. The mean relative error（ MRE） and coefficient of determination（ R2） are1. 90% - 36. 29% and 0. 959 - 0. 998 for dimethyl sulfoxide,13. 56% - 19. 19% and 0. 990 - 0. 995 for glycerol,8. 89% - 22. 09% and 0. 969 - 0. 988 for ethylene glycol,and 5. 35% - 23. 76% and 0. 971 -0. 992 for propylene glycol,respectively.