We report a new strategy that allows reversible tuning of the stiffness and stress–relaxation of viscoelastic hydrogels cross-linked via hydrazone bonds by incorporating a small-molecule competitor. The competitor molecule competes for the formation of reversible hydrazone bonds and temporarily reduces the cross-linking density in the hydrogel, thus softening the hydrogel and accelerating its stress–relaxation. By rapidly diffusing the competitor in and out of the hydrogel, the mechanical properties of hydrogels can be reversibly altered over many cycles. We further examined the biocompatibility of the competitor and explored its application in cell delivery via injection by temporarily adjusting the hydrogel mechanical properties to improve cell viability during the injection.

中文翻译：

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使用竞争分子可逆地调节粘弹性水凝胶的机械性能

我们报告了一种新策略，该策略允许通过掺入小分子竞争剂来可逆地调节通过腙键交联的粘弹性水凝胶的刚度和应力松弛。竞争分子竞争形成可逆的腙键并暂时降低水凝胶中的交联密度，从而软化水凝胶并加速其应力松弛。通过将竞争者快速扩散进水凝胶和从水凝胶中扩散出来，水凝胶的机械性能可以在许多循环中可逆地改变。我们进一步检查了竞争对手的生物相容性，并通过暂时调整水凝胶机械性能以提高注射过程中的细胞活力来探索其在注射细胞递送中的应用。