Enzyme-Regulated Healable Polymeric Hydrogels

Abstract

The enzyme-regulated healable polymeric hydrogels are a kind of emerging soft material capable of repairing the structural defects and recovering the hydrogel properties, wherein their fabrication, self-healing, or degradation is mediated by enzymatic reactions. Despite achievements that have been made in controllable cross-linking and de-cross-linking of hydrogels by utilizing enzyme-catalyzed reactions in the past few years, this substrate-specific strategy for regulating healable polymeric hydrogels remains in its infancy, because both the intelligence and practicality of current man-made enzyme-regulated healable materials are far below the levels of living organisms. A systematic summary of current achievements and a reasonable prospect at this point can play positive roles for the future development in this field. This Outlook focuses on the emerging and rapidly developing research area of bioinspired enzyme-regulated self-healing polymeric hydrogel systems. The enzymatic fabrication and degradation of healable polymeric hydrogels, as well as the enzymatically regulated self-healing of polymeric hydrogels, are reviewed. The functions and applications of the enzyme-regulated healable polymeric hydrogels are discussed.

Stimuli responsive dynamic transformations in supramolecular gels

“…Enzyme-triggered assembly of small molecules provides a facile approach to study the properties of the assembled structures in a cellular environment which is important for exploring the possibilities of supramolecular gels in biomedical research. [76][77][78] Enzyme responsive assemblies are usually formed by enzyme-reactive centres on a gelator skeleton which leads to either formation or cleavage of a covalent bond upon enzymatic reaction. Such chemical transformations result in a change in chemical structure of the building blocks which in turn perturbs the existing non-covalent interactions, leading to selfassembly.…”

Systems Chemistry in Self‐Healing Materials

“…In addition to the microcapsule‐ and microvascular‐based self‐healing strategies, systems chemistry can be useful in recovering both the structure and property of synthetic materials by rationally integrating dynamic chemistry with chemical reaction networks through learning the hierarchically and temporally controlled healing strategy in biological systems. Along these lines, we recently embedded enzymes such as urease (Figure 4a) [16d] and glucose oxidase (GOx, Figure 4b) [16c] or microbes such as baker's yeast ( Saccharomyces cerevisiae , Figure 4c) [30] in the polymer hydrogels with kinetically locked covalent bonds or kinetically inert metal‐ligand interactions [31] . When healing was needed, the fracture surfaces could be fed with proper chemical nutrients (or fuels), in which case a locally activated state was temporally programmed for structural healing.…”

Nonequilibrium Regulation of Interfacial Chemistry for Dissipative Supramolecular Assembly of Macroscopic Hydrogels

“…8,9 Learning from nature, the dissipative assembly of synthetic molecules driven by chemical fuels was suggested in 2010 by Boekhoven et al 10 Now, scientists have successfully constructed diverse nonequilibrium systems by adopting various types of microscopic building blocks, such as small molecules, [11][12][13][14] synthetic polymers, 15,16 biomacromolecules, 17,18 and nanoparticles. [19][20][21] Recent work has also shown promise in controlling drug release behaviors 22 and self-healing functions 15,[23][24][25] in nonequilibrium systems. Despite these achievements, current studies in this filed are still focusing on the micro level, and far too little attention has been paid to the macroscopic nonequilibrium assembly.…”