Kuo Catherine K, Ma Peter X
Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, Michigan 48109-1078, USA.
J Biomed Mater Res A. 2008 Mar 15;84(4):899-907. doi: 10.1002/jbm.a.31375.
Ionically crosslinked alginate hydrogels are attractive scaffolds because of their biocompatibility and mild gelation reaction that allows for gentle cell incorporation. However, the instability of ionically crosslinked hydrogels in an aqueous environment is a challenge that limits their application. This report presents a novel method to control the dimensions and mechanical properties of ionically crosslinked hydrogels via control of the ionic concentration of the medium. Homogeneous calcium-alginate gels were incubated in physiological saline baths adjusted to specific calcium ion concentrations. Swelling and shrinking occurred at low and high ionic concentrations of the medium, respectively, while an "optimal" intermediate calcium ion concentration of the medium was found to maintain original size and shape of the hydrogel. This optimal calcium ion concentration was found to be a function of crosslinking density and polymer concentration of the hydrogel and chemical composition of the alginate. The effects of optimal and high calcium ion concentrations of the medium on swelling behavior, calcium content, dry weight, and mechanical properties of the immersed hydrogels were investigated. It was found that the resulting hydrogel composition and mechanical properties depended on not only the calcium concentration of the medium, but also the crosslinking density and polymer concentration of the gel. In an 8-week experiment, controlled dimensions and mechanical properties of alginate gels in an aqueous environment were demonstrated. This new technique significantly enhances the potential of alginate hydrogels for tissue engineering and other biomedical applications.
离子交联藻酸盐水凝胶因其生物相容性和温和的凝胶化反应（允许细胞轻柔地掺入）而成为有吸引力的支架材料。然而，离子交联水凝胶在水性环境中的不稳定性是一个挑战，限制了它们的应用。本报告提出了一种通过控制介质离子浓度来控制离子交联水凝胶尺寸和机械性能的新方法。将均匀的钙 - 藻酸盐凝胶置于调整到特定钙离子浓度的生理盐水中孵育。在介质离子浓度低时发生膨胀，在高时发生收缩，而发现介质中存在一个“最佳”的中间钙离子浓度可维持水凝胶的原始尺寸和形状。发现这个最佳钙离子浓度是水凝胶交联密度、聚合物浓度以及藻酸盐化学成分的函数。研究了介质中最佳和高钙离子浓度对浸泡水凝胶的溶胀行为、钙含量、干重和机械性能的影响。发现所得水凝胶的组成和机械性能不仅取决于介质的钙浓度，还取决于凝胶的交联密度和聚合物浓度。在一个为期8周的实验中，展示了在水性环境中藻酸盐凝胶尺寸和机械性能的可控性。这项新技术显著增强了藻酸盐水凝胶在组织工程和其他生物医学应用中的潜力。
