Department of Chemical Engineering and Applied Chemistry, Donnelly Centre , University of Toronto , 160 College Street , Toronto , Ontario M5S3E1 , Canada.
Department of Chemistry , University of Windsor , Windsor , Ontario N9B 3P4 , Canada.
Biomacromolecules. 2018 Mar 12;19(3):926-935. doi: 10.1021/acs.biomac.7b01715. Epub 2018 Feb 23.
Engineered hydrogels have been extensively used to direct cell function in 3D cell culture models, which are more representative of the native cellular microenvironment than conventional 2D cell culture. Previously, hyaluronan-furan and bis-maleimide polyethylene glycol hydrogels were synthesized via Diels-Alder chemistry at acidic pH, which did not allow encapsulation of viable cells. In order to enable gelation at physiological pH, the reaction kinetics were accelerated by replacing the hyaluronan-furan with the more electron-rich hyaluronan-methylfuran. These new click-cross-linked hydrogels gel faster and at physiological pH, enabling encapsulation of viable cells, as demonstrated with 3D culture of 5 different cancer cell lines. The methylfuran accelerates Diels-Alder cycloaddition yet also increases the retro Diels-Alder reaction. Using computational analysis, we gain insight into the mechanism of the increased Diels-Alder reactivity and uncover that transition state geometry and an unexpected hydrogen-bonding interaction are important contributors to the observed rate enhancement. This cross-linking strategy serves as a platform for bioconjugation and hydrogel synthesis for use in 3D cell culture and tissue engineering.
通过狄尔斯-阿尔德（Diels-Alder）化学反应在酸性 pH 值下合成了透明质酸呋喃和双马来酰亚胺聚乙二醇水凝胶，这种方法不能封装活细胞。为了在生理 pH 值下实现凝胶化，通过用电子密度更高的透明质酸甲基呋喃代替透明质酸呋喃来加速反应动力学。这些新的点击交联水凝胶在生理 pH 值下更快地凝胶化，从而能够封装活细胞，这在 5 种不同癌细胞系的 3D 培养中得到了证明。甲基呋喃加速了 Diels-Alder 环加成反应，但也增加了逆 Diels-Alder 反应。通过计算分析，我们深入了解了增加的 Diels-Alder 反应性的机制，并揭示了过渡态几何形状和意想不到的氢键相互作用是观察到的速率增强的重要贡献者。这种交联策略可作为用于 3D 细胞培养和组织工程的生物共轭和水凝胶合成的平台。
