Department of Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
Department of Chemical Engineering, Queen's University, Kingston, ON K7L 3N6, Canada.
J Control Release. 2015 Feb 10;199:10-6. doi: 10.1016/j.jconrel.2014.12.010. Epub 2014 Dec 10.
The ability to estimate the diffusion coefficient of a solute within hydrogels has important application in the design and analysis of hydrogels used in drug delivery, tissue engineering, and regenerative medicine. A number of mathematical models have been derived for this purpose; however, they often rely on fitted parameters and so have limited predictive capability. Herein we assess the ability of the obstruction-scaling model to provide reasonable estimates of solute diffusion coefficients within hydrogels, as well as the assumption that a hydrogel can be represented as an entangled polymer solution of an equivalent concentration. Fluorescein isothiocyanate dextran solutes were loaded into sodium alginate solutions as well as hydrogels of different polymer volume fractions formed from photoinitiated cross-linking of methacrylate sodium alginate. The tracer diffusion coefficients of these solutes were measured using fluorescence recovery after photobleaching (FRAP). The measured diffusion coefficients were then compared to the values predicted by the obstruction-scaling model. The model predictions were within ±15% of the measured values, suggesting that the model can provide useful estimates of solute diffusion coefficients within hydrogels and solutions. Moreover, solutes diffusing in both sodium alginate solutions and hydrogels were demonstrated to experience the same degree of solute mobility restriction given the same effective polymer concentration, supporting the assumption that a hydrogel can be represented as an entangled polymer solution of equivalent concentration.
估算溶质在水凝胶中扩散系数的能力在药物输送、组织工程和再生医学中使用水凝胶的设计和分析中具有重要应用。为此已经衍生出许多数学模型；然而，它们通常依赖于拟合参数，因此预测能力有限。在此，我们评估了阻塞缩放模型在提供水凝胶内溶质扩散系数的合理估计方面的能力，以及假设水凝胶可以表示为等效浓度的缠结聚合物溶液的假设。荧光素异硫氰酸酯葡聚糖示踪剂被加载到海藻酸钠溶液以及由甲基丙烯酰化海藻酸钠光引发交联形成的不同聚合物体积分数的水凝胶中。使用荧光恢复后光漂白（FRAP）测量这些示踪剂的扩散系数。然后将测量的扩散系数与阻塞缩放模型预测的值进行比较。模型预测值在测量值的±15%以内，表明该模型可以为水凝胶和溶液中的溶质扩散系数提供有用的估计。此外，在相同的有效聚合物浓度下，扩散在海藻酸钠溶液和水凝胶中的溶质被证明经历相同程度的溶质迁移限制，支持水凝胶可以表示为等效浓度的缠结聚合物溶液的假设。
