The atomic force microscopy force–volume technique was used to investigate the surface properties of two hydrogels during their enzymatic degradation. Agarose gels with concentrations of 0.5, 1.0 and 1.5% w/v were selected for the degradation study to show that the mechanical effects of degradation could be measured in a spatially resolved way on the hydrogel surface. The agarase enzyme was used to degrade the agarose gels. The agarose gels were found to be heterogeneous with multiple stiffness domains that were degraded at different erosion rates. It was inferred that agarose gels contained both tightly and loosely packed regions. The loosely packed regions degraded first, followed by the regions that were packed more tightly. The second hydrogels containing hyaluronic acid and gelatin with 5% w/v hyaluronic acid and 5% w/v gelatin cross-linked in equal amounts were also studied. These hybrid gels were degraded either by using hyaluronidase or collagenase type IV. With hyaluronidase, gelatin was left on the surface as a homogeneous layer. With collagenase, cross-linked hyaluronic acid remained on the surface. Post-degradation the hyaluronic acid-rich surface had a stiffness of ∼20 kPa, while the gelatin-rich surface stiffness was only ∼15 kPa.

中文翻译：

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酶降解过程中水凝胶刚度的空间分辨映射

原子力显微镜力-体积技术用于研究两种水凝胶在酶促降解过程中的表面性质。选择浓度为 0.5、1.0 和 1.5% w/v 的琼脂糖凝胶用于降解研究，以表明降解的机械效应可以在水凝胶表面以空间分辨的方式测量。琼脂酶用于降解琼脂糖凝胶。发现琼脂糖凝胶是异质的，具有在不同侵蚀速率下降解的多个刚度域。据推断，琼脂糖凝胶包含紧密和松散的区域。松散堆积的区域首先降解，其次是堆积更紧密的区域。还研究了含有透明质酸和明胶的第二种水凝胶，其中 5% w/v 透明质酸和 5% w/v 明胶等量交联。这些混合凝胶通过使用透明质酸酶或 IV 型胶原酶降解。使用透明质酸酶，明胶作为均质层留在表面上。使用胶原酶，交联的透明质酸保留在表面。降解后富含透明质酸的表面刚度为~20 kPa，而富含明胶的表面刚度仅为~15 kPa。