David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Department of Anesthesiology, Boston Children's Hospital, Boston, MA, 02115, USA.
Adv Mater. 2017 May;29(19). doi: 10.1002/adma.201605947. Epub 2017 Mar 15.
Hydrogels play a central role in a number of medical applications and new research aims to engineer their mechanical properties to improve their capacity to mimic the functional dynamics of native tissues. This study shows hierarchical mechanical tuning of hydrogel networks by utilizing mixtures of kinetically distinct reversible covalent crosslinks. A methodology is described to precisely tune stress relaxation in PEG networks formed from mixtures of two different phenylboronic acid derivatives with unique diol complexation rates, 4-carboxyphenylboronic acid, and o-aminomethylphenylboronic acid. Gel relaxation time and the mechanical response to dynamic shear are exquisitely controlled by the relative concentrations of the phenylboronic acid derivatives. The differences observed in the crossover frequencies corresponding to pK differences in the phenylboronic acid derivatives directly connect the molecular kinetics of the reversible crosslinks to the macroscopic dynamic mechanical behavior. Mechanical tuning by mixing reversible covalent crosslinking kinetics is found to be independent of other attributes of network architecture, such as molecular weight between crosslinks.
水凝胶在许多医学应用中起着核心作用，新的研究旨在通过设计其机械性能来提高其模拟天然组织功能动态的能力。本研究通过利用两种不同动力学可逆共价交联剂的混合物，展示了水凝胶网络的层次化机械调节。本文描述了一种精确调节聚乙二醇（PEG）网络应力松弛的方法，该方法是通过混合两种不同的苯硼酸衍生物（具有独特二醇络合速率的 4-羧基苯硼酸和邻氨基甲基苯硼酸）形成的。凝胶松弛时间和对动态剪切的机械响应可以通过苯硼酸衍生物的相对浓度来精确控制。在对应于苯硼酸衍生物 pKa 差异的交越频率上观察到的差异，直接将可逆交联的分子动力学与宏观动态力学行为联系起来。通过混合可逆共价交联动力学进行机械调节，与网络结构的其他属性（例如交联点之间的分子量）无关。
