School of Chemistry, the Australian Centre for Nanomedicine and The ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, the University of New South Wales , Sydney, NSW 2052, Australia.
J Am Chem Soc. 2018 Feb 28;140(8):2869-2874. doi: 10.1021/jacs.7b12198. Epub 2018 Feb 16.
It remains challenging to program soft materials to show dynamic, tunable time-dependent properties. In this work, we report a strategy to design transient supramolecular hydrogels based on kinetic control of competing reactions. Specifically, the pH-triggered self-assembly of a redox-active supramolecular gelator, N,N'-dibenzoyl-l-cystine (DBC) in the presence of a reducing agent, which acts to disassemble the system. The lifetimes of the transient hydrogels can be tuned simply by pH or reducing agent concentration. We find through kinetic analysis that gel formation hinders the ability of the reducing agent and enables longer transient hydrogel lifetimes than would be predicted. The transient hydrogels undergo clean cycles, with no kinetically trapped aggregates observed. As a result, multiple transient hydrogel cycles are demonstrated and can be predicted. This work contributes to our understanding of designing transient assemblies with tunable temporal control.
将软物质编程为具有动态、可调的时变特性仍然具有挑战性。在这项工作中，我们报告了一种基于竞争反应的动力学控制来设计瞬态超分子水凝胶的策略。具体来说，在还原剂存在下，氧化还原活性的超分子凝胶剂 N,N'-二苯甲酰-L-胱氨酸（DBC）的 pH 触发自组装，还原剂的作用是使系统解体。瞬态水凝胶的寿命可以通过 pH 值或还原剂浓度简单地进行调节。我们通过动力学分析发现，凝胶形成阻碍了还原剂的能力，使瞬态水凝胶的寿命比预期的要长。瞬态水凝胶经历了干净的循环，没有观察到动力学捕获的聚集体。结果，展示并可以预测多个瞬态水凝胶循环。这项工作有助于我们理解具有可调时间控制的瞬态组装的设计。
