Host‐Fueled Transient Supramolecular Hydrogels

Abstract

Inspired by the dissipative assembly in biological systems, transient hydrogels based on supramolecular interactions have been developed that are under thermodynamic nonequilibrium states. Host-guest interactions possess excellent properties including high selectivity and adjustable association constants, which are beneficial for controlling the properties and behaviors of transient colloidal materials. In this work, a host-fueled transient supramolecular hydrogel system is reported. The hydrogels based on host-guest interactions are formed by addition of a chemical fuel, α-cyclodextrin (α-CD), to the aqueous solutions containing Pluronic F127 and α-amylase. Meanwhile, as the host molecule of α-CD consumes, the hydrogel networks start to collapse. The lifetime of the transient supramolecular hydrogels can be precisely controlled by adjusting the temperature and hydrogel composition, and repeated sol-to-gel-to-sol transitions can be realized by refueling the system with α-CD. This study provides a new approach to regulate the nonequilibrium host-guest inclusion system by fueling it with host molecules.

Comprehensive Chemical Experiment of Dynamic Reconfiguration of Supramolecular Assemblies

“…化学奖 [1,2] 。这些重要成果是人类向生命体深入学习而获得的。在生物系统中，化学燃料或能量的输 入可激活结构单元，使其自组装形成瞬态结构。生命体利用这种受控于耗散热力学的非平衡超分子 组装来调整其结构和功能以实现自我调节 [3][4][5][6][7][8] 。受此启发，研究者们设计出了一系列化学燃料驱动 的、瞬态的、远离热力学平衡态的超分子体系，并将其应用于智能材料的研究和开发 [9][10][11][12][13][14][15][16] 。开发非 平衡组装体系并探究其组装机制可以加深对生命体的理解，并在设计和开发新型智能材料中发挥重 要作用。 利用非平衡组装可以制备出结构、功能、寿命可调的瞬态材料，其中以瞬态水凝胶材料最为典 型 [17] 。近年来，科学家通过模仿生命系统中的组装-解组装行为并结合化学反应网络，制备出了多种 可应用于药物控释及信息加密等领域的瞬态水凝胶材料 [9,10,15] 。与此同时，对合成体系非平衡组装机 制的深入研究同样备受关注。设计相关实验，可使学生初步接触超分子化学领域的前沿问题，激发 其学习兴趣与热情，并锻炼其综合实验技能。 在本实验中，将构建一个宏观上表现出沉淀→凝胶→沉淀转变现象的非平衡组装体系，并提出 超分子组装体动态重构机制。该实验操作简便，现象明显，适合实验教学，除基础操作外，还加入 透射电子显微镜(TEM)、荧光光谱仪、圆二色谱仪的使用，让学生在实验过程中不仅可以学习到非 平衡组装体系的构建方法及组装机制，还能满足学生学习现代科学表征技术的需求。…”

Short Peptide-Based Smart Thixotropic Hydrogels

“…Host–guest chemistry is one of the leading techniques to create a supramolecular peptide hydrogel [ 133 , 134 , 135 , 136 , 137 ]. The peptide sequence, Fmoc-ArgGlyAspSer (T 4 P13), was chosen by Ravoo’s group owing to its good water solubility and high biocompatibility nature [ 138 ].…”

Smart Hydrogels Bearing Transient Gel–Sol–Gel Transition Behavior Driven by a Biocompatible Chemical Fuel

“…Inspired by nature, chemically fueled dissipative self-assembly has been an active field of research and discussion, giving rise to numerous beautiful supramolecular materials that are capable of transiently changing their structures and functionalities over time. − One of the most important examples is the chemically fueled smart supramolecular hydrogels, which show enticing applications in the field of biomedicine. , Typically, the input of high-energy chemical fuel temporally converts the non-assembling precursors into gelators, which thereby self-assemble into hydrogels; however, once the chemical fuel is used out, the gelators will return to the original non-assembling state spontaneously, leading to a dynamic sol–gel–sol transition. − Along this line, various smart supramolecular hydrogels have been developed with the consumption of high-energy chemicals, such as methylating reagents, 1-(3-dimethylaminopropyl)-(3-ethyl)­carbonimide, − disulfide reducing agents, , and trichloroacetic acid (TCA) . However, to date, most of the reported examples undergo a fueled sol–gel–sol transition, where the gels reside under unstable states incapable of functioning steadily.…”