The diverse requirements of hydrogels for tissue engineering motivate the development of cross-linking reactions to fabricate hydrogel networks with specific features, particularly those amenable to the activity of biological materials (e.g., cells, proteins) that do not require exposure to UV light. We describe gelation kinetics for a library of thiolated poly(ethylene glycol) sulfhydryl hydrogels undergoing enzymatic cross-linking via horseradish peroxidase, a catalyst-driven reaction activated by hydrogen peroxide. We report the use of small-amplitude oscillatory shear (SAOS) to quantify gelation kinetics as a function of reaction conditions (hydrogen peroxide and polymer concentrations). We employ a novel approach to monitor the change of viscoelastic properties of hydrogels over the course of gelation (Δ tgel) via the time derivative of the storage modulus (d G'/d t). This approach, fundamentally distinct from traditional methods for defining a gel point, quantifies the time interval over which gelation events occur. We report that gelation depends on peroxide and polymer concentrations as well as system temperature, where the effects of hydrogen peroxide tend to saturate over a critical concentration. Further, this cross-linking reaction can be reversed using l-cysteine for rapid cell isolation, and the rate of hydrogel dissolution can be monitored using SAOS.

中文翻译：

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酶交联 PEG 水凝胶凝胶动力学的流变学分析。

组织工程对水凝胶的不同要求促进了交联反应的发展，以制造具有特定功能的水凝胶网络，特别是那些适合不需要暴露于紫外线的生物材料（例如细胞、蛋白质）活性的水凝胶网络。我们描述了硫醇化​​聚（乙二醇）硫氢基水凝胶库通过辣根过氧化物酶进行酶交联的凝胶化动力学，辣根过氧化物酶是一种由过氧化氢激活的催化剂驱动的反应。我们报告了使用小振幅振荡剪切（SAOS）来量化凝胶动力学作为反应条件（过氧化氢和聚合物浓度）的函数。我们采用一种新方法通过储能模量的时间导数 (d G'/dt) 来监测水凝胶在凝胶化过程中粘弹性特性的变化 (Δ tgel)。这种方法从根本上不同于定义凝胶点的传统方法，它量化了凝胶事件发生的时间间隔。我们报告说，凝胶化取决于过氧化物和聚合物浓度以及系统温度，其中过氧化氢的影响往往在临界浓度以上饱和。此外，可以使用 L-半胱氨酸逆转这种交联反应以快速分离细胞，并且可以使用 SAOS 监测水凝胶溶解速率。