基于动态可逆非共价体系的自愈合水凝胶构建方法研究进展

Progress on Constructing of Self-healing Hydrogel Based on Dynamic Reversible Non-covalent System

材料的完整性是保证其呈现应有性能的前提,任何破损或缺陷都可能导致材料性能不能满足使用需求。在众多材料中,用作药物缓释载体、组织工程支架和功能器件涂层的水凝胶因其特殊的应用环境而对自我修复性能需求迫切。自愈合水凝胶在受到外界破坏后能自我修复以维持初始性能,保证了使用过程中材料的安全性和可靠性。因此,具有自愈合性能的新型功能材料是目前重要的研究方向。基于高分子链之间相互作用力形成的自愈合水凝胶分为两类:(1)通过动态共价键形成的水凝胶,包括双硫键、Diels-Alder环加成反应、亚胺键/席夫碱作用等;(2)通过范德华力或氢键等非共价键作用,即物理交联形成的水凝胶,包括氢键作用、主体-客体之间力的作用、聚阴阳离子间的相互作用、金属配体的相互作用、疏水缔合等。由于共价键的稳定性,大多数共价键交联所形成的水凝胶稳定存在并表现出良好的力学性能。然而,这些水凝胶存在对外界刺激反应性低、制造之后不能被重塑、受到破坏之后不能自我修复等局限性,因此发展基于动态共价键或物理交联的自愈合水凝胶已成趋势。自愈合水凝胶不仅具有水凝胶独特的溶胀性能、极高的含水量、良好的生物组织相似性,而且具有自我修复断层的能力,可用于组织工程、伤口敷料、药物缓释、生物传感等生物医学研究领域,可有效延长材料的使用寿命,具有极好的应用前景。本文介绍了近年来基于动态可逆非共价体系构建自愈合水凝胶的研究进展,按照不同的愈合机理对自愈合水凝胶进行分类,分别讨论了基于氢键、可逆金属配位作用、疏水缔合以及多种作用力相结合等作用机理构建自愈合水凝胶的方法和应用进展,分析了基于动态可逆非共价构建自愈合水凝胶可能面临的问题,并对其发展前景进行了展望,以期指导此类水凝胶的设计、制备与应用。

The integrity of materials is a prerequisite for ensuring their performance.Any damage or defect may result in materials not meeting the requirements of application.For all kinds of materials,self-healing properties are strongly needed,especially for the hydrogels used as drug delivery carriers,tissue engineering scaffolds and functional device coatings because of their special application requirements.Developing self-healing hydrogels which can heal itself to maintain its initial performance after being damaged is vital to ensure the safety and reliability of materials in the use cycle,and thus has attracted more and more attentions.In general,self-healing hydrogels can be divided into two types based on the forces between polymer chains.The first kind is formed by dynamic covalent bonds,including disulfide bonds,Diels-Alder cycloaddition reaction,imine bond/Schiff base interaction,etc.Others are formed by physically crosslinking of non-valent bonds like hydrogen bonds or van der Waals’force,host-guest interaction,the interaction between polyelectrolyte,interaction of metal ligand,hydrophobic association,etc.Due to the stability of covalent bonds,most hydrogels formed by covalent bonds are stable and can exhibit good mechanical properties.Howe-ver,these hydrogels have many limitations,including poor response to external stimuli,inability to be remodeled after being manufactured,and unable to heal themselves after being damaged.Thus,the development of self-healing hydrogels based on dynamic covalent or physical crosslinking has become a trend.Self-healing hydrogel not only exhibit high swelling ratio and water content,biocompatibility and biodegradability,but also has the ability to repair the fault,which can be used for tissue engineering,wound dressing,drug release and biosensing fields,prolonging the lifespan of materials and showing excellent application potential.This review introduces the progress on the development of self-healing hydrogels based on dynamic reversible non-covalent system in recent years.The self-healing hydrogels are classified according to different healing mechanisms.The fabrication methods and application fields of self-healing hydrogels based on hydrogen bonding,reversible metal coordination,hydrophobic association and various interaction forces are reviewed respectively,and the problems and prospects of hydrogels based on dynamic reversible non-covalent system are discussed,aiming at providing ideas for the design,preparation and application of such hydrogels.