抗冻高分子水凝胶的设计策略及应用进展

高分子水凝胶具有优异的生物相容性、延展性和变形能力,在诸多领域显示出巨大的应用前景。然而,在低温下水分子冻结,水凝胶会失去其优异的性能。近年来抗冻水凝胶材料受到广大研究者的青睐。文中主要综述了抗冻高分子水凝胶的设计策略与方法,重点介绍了3类抗冻水凝胶,即基于离子水合作用的抗冻水凝胶、基于氢键作用的抗冻水凝胶及基于离子水合与氢键协同作用的抗冻水凝胶,并阐述了抗冻水凝胶材料在软致动器、超级电容器/电池和传感器等领域的应用进展,最后讨论了抗冻水凝胶在未来发展中仍然需要解决的关键性问题和发展方向。     

纤维素基导电水凝胶的合成及其结构性能表征

以离子液体(氯化-1-丁基-三甲基咪唑,BMIMCl)溶解微晶纤维素(MCC),以N,N-亚甲基双丙烯酰胺作为交联剂形成的纤维素水凝胶为基体,同时吡咯(Py)作为导电聚合物单体,制备了纤维素基导电水凝胶。对MCC/PPy复合导电水凝胶的化学结构和表面形貌进行了表征,研究了该导电水凝胶的导电性、溶胀性能和热稳定性。结果表明,PPy与MCC水凝胶形成了具有半互穿网络结构的导电水凝胶,该水凝胶表面呈蜂窝状;其电导率数量级可达10-4~10-3,且对甲苯磺酸钠掺杂可大幅提高其电导率;随着MCC浓度的增加,纤维素水凝胶的平衡溶胀率呈下降趋势,所得导电水凝胶的溶胀率比纯纤维素水凝胶的溶胀率略有下降,但仍能维持500%的水平;此外,该导电水凝胶的热稳定性较纯MCC水凝胶有所下降。     

抗菌水凝胶的研究进展

抗菌水凝胶在现代医学领域有着重要的地位,更优的抗菌性能一直是专家学者们的研究重点。对天然抗菌剂/水凝胶、无机抗菌剂/水凝胶和有机抗菌剂/水凝胶的研究进展进行了综述,新型抗菌水凝胶中双重模式抗菌的MOFs/水凝胶将是今后研究的重点。     

高强度水凝胶的制备及其研究进展

水凝胶因其拥有较高的溶胀比和极高的含水率,被广泛应用于各种领域,但力学性能较弱的缺点限制了其在组织工程、软体机器人、可穿戴电子设备等高负载领域的发展。综述了近年来纳米复合水凝胶、双网络水凝胶、大分子微球复合水凝胶、疏水缔合水凝胶等高强度水凝胶的制备方法及研究进展;讨论了各类型高强水凝胶的特点并指出了目前研究中存在的问题;同时,对高强度水凝胶未来的研究方向进行了展望。     

合成水凝胶材料在组织工程中的应用

水凝胶材料因其高保湿、高吸水等特点,在组织工程、生物医药等领域具有广阔的现实意义和应用前景,特别是作为药物缓释剂、组织填充剂、酶的包埋剂、人造皮肤等方面。按原料来源分,水凝胶材料可分为天然水凝胶材料和合成水凝胶材料。尽管天然水凝胶材料的生物相容性、生物降解性优于合成水凝胶材料,但合成水凝胶材料具有相对较高的机械性能,备受研究者青睐。近年来,如何将两种类型的水凝胶材料的优点结合在一起应用成为研究热点。大量关于水凝胶材料的改性研究相继开展,并取得了一定进展。主要概述了以聚乙二醇、聚乙烯醇、聚丙烯酰胺为基础合成的水凝胶材料的研究及发展状况,并对几种水凝胶材料进行了初步生物学评价,探讨了此类水凝胶在组织工程中的应用。     

PAAm-LGSNa+光致变色水凝胶的合成及表征

采用接枝法将木质素磺酸钠接入聚丙烯酰胺水凝胶中,合成了聚丙烯酰胺-木质素磺酸钠水凝胶,通过浸泡工艺将钼酸铵引入水凝胶网络中实现视觉显示。UV-Vis、FT-IR和SEM分别测量了木质素磺酸钠-聚丙烯酰胺水凝胶的吸光度和透明度、结构、形貌。UV-Vis测量结果表明该水凝胶具有低成本,易于制备,5 min内快速响应的优异性能。此外,水凝胶的光致变色和褪色过程可以在紫外光照射,不同时间和温度下精确控制。FT-IR测量结果表明成功将木质素磺酸钠接入聚丙烯酰胺水凝胶中。SEM研究结果表明,水凝胶在完全干燥后表现出致密的结构,这使得水凝胶在光致变色后不易褪色。     

环糊精衍生物水凝胶材料的研究进展

水凝胶是一种由化学或物理交联的高分子聚合材料,具有亲水性的三维网络结构,使其能够吸收并保持大量的水分。水凝胶相对其他材料有着明显优势,其具有含水量高、性质柔软、通透性高、生物相容性好等优点,这些优异的性质使水凝胶在工业、农业、生物医学乃至生活中都有着广泛的应用。近些年来国内外研究者都致力于开发新型水凝胶,以解决传统水凝胶存在的力学强度差、功能单一的问题。因此,涌现了大批多功能、高强度的新型水凝胶,如温度、pH、光、电磁刺激响应性水凝胶,双网络、互穿网络水凝胶,纳米复合水凝胶,自愈合性水凝胶。其中,环糊精及其衍生物的引入是改善水凝胶不足的重要方法之一。环糊精存在特殊的外缘亲水、内部疏水的环状分子结构以及疏水性空腔,能够通过主客体偶合作用稳定络合疏水性分子。近年来,研究者们充分利用环糊精独特的结构和性质,在设计更好的环糊精衍生物水凝胶结构和功能方面不断地进行尝试,取得了丰硕的研究成果,制备了一系列具有优异性能的环糊精及其衍生物高分子水凝胶。环糊精及其衍生物水凝胶不仅在力学性能方面表现出优势,还具有显著的功能性,如刺激响应性、自修复性、形状记忆性、可注射性等。目前,已报道的环糊精衍生物水凝胶结构多样、性质各异,按其网络结构可分为:(1)化学修饰环糊精作为交联剂合成水凝胶;(2)环糊精衍生物的主客体超分子水凝胶;(3)环糊精衍生物的物理/化学双交联水凝胶;(4)环糊精衍生物的滑环水凝胶。各种交联结构的环糊精衍生物水凝胶的开发,赋予了水凝胶不同的功能和性质,为突破传统水凝胶的应用瓶颈提供了思路,使其在催化工程、药物控释、骨/软骨组织修复和水污染物净化领域具有广阔的应用前景。本文归纳了环糊精衍生物高分子水凝胶的研究进展,按水凝胶的交联结构对环糊精衍生物水凝胶进行分类,分别对环糊精分子、环糊精衍生物水凝胶的结构、制备方法、应用等进行介绍,分析了环糊精衍生物高分子水凝胶所面临的问题并展望其前景,以期为制备多功能、高强度环糊精衍生物水凝胶提供参考。     

DNA水凝胶的设计与构建

DNA水凝胶同时兼有DNA的生物功能和水凝胶的骨架功能,具有良好的生物相容性、生物可降解性、选择特异性、结构可设计性以及精确的分子识别能力等优点,在生物医学领域中应用前景广阔。随着研究的持续深入进行,研究人员巧妙地设计了各种各样的DNA水凝胶的交联制备方法,并通过向其中引入其它功能分子或基元,或与其它类型的功能材料进行结合,构建了具有优异性能的DNA水凝胶。文中从物理水凝胶和化学水凝胶两方面,介绍了DNA水凝胶的研究动态,重点分析和阐述了DNA水凝胶的设计和构建方法以及内部交联机制,并对所存在的问题及未来研究发展趋势进行了总结和展望,为DNA水凝胶的进一步发展提供参考。     

快速响应的聚(N-异丙基丙烯酰胺)水凝胶的合成及性能

以羧甲基纤维素的水溶液为反应介质制备了快速响应的温度敏感性聚(N-异丙基丙烯酰胺)水凝胶。利用DSC对其相转变温度进行了表征,并测定了不同温度下达到平衡时水凝胶的溶胀比,研究了水凝胶的去溶胀动力学。结果表明,在聚合/交联过程中羧甲基纤维素的存在对PN IPA水凝胶的相转变温度几乎没有影响;与传统水凝胶相比,该水凝胶的溶胀性能有所提高,并且具有较快的响应速率。     

不同体系的双网络水凝胶及其增强机理

双网络水凝胶是由两种不同性质的聚合物形成的互穿网络,第一层为紧密交联的刚而脆聚电解质网络,第二层为松散交联的软而韧中性网络.双网络水凝胶具有极高的机械强度和韧性,甚至可以与橡胶相媲美.其中,刚而脆聚电解质网络为双网络水凝胶提供了“牺牲键”,起到分散外界应力的作用;而软而韧的中性聚合物填补于剐性网络中,为双网络水凝胶提供了支架,保持水凝胶外形.基于上述机理,研究者设计合成了具有高强度、良好生物相容性、低摩擦和低磨损等特性的双网络水凝胶.着重讨论了不同体系双网络水凝胶的力学性能和增强机理,并展望了双网络水凝胶研究前景.     

Near‐Infrared Light Responsive Multi‐Compartmental Hydrogel Particles Synthesized Through Droplets Assembly Induced by Superhydrophobic Surface

Light‐responsive hydrogel particles with multi‐compartmental structure are useful for applications in microreactors, drug delivery and tissue engineering because of their remotely‐triggerable releasing ability and combinational functionalities. The current methods of synthesizing multi‐compartmental hydrogel particles typically involve multi‐step interrupted gelation of polysaccharides or complicated microfluidic procedures with limited throughput. In this study, a two‐step sequential gelation process is developed to produce agarose/alginate double network multi‐compartmental hydrogel particles using droplets assemblies induced by superhydrophobic surface as templates. The agarose/alginate double network multi‐compartmental hydrogel particles can be formed with diverse hierarchical structures showing combinational functionalities. The synthesized hydrogel particles, when loaded with polypyrrole (PPy) nanoparticles that act as photothermal nanotransducers, are demonstrated to function as near‐infrared (NIR) light triggerable and deformation‐free hydrogel materials. Periodic NIR laser switching is applied to stimulate these hydrogel particles, and pulsatile release profiles are collected. Compared with massive reagents released from single‐compartmental hydrogel particles, more regulated release profiles of the multi‐compartmental hydrogel particles are observed.     

Photocontrolled Healable Structural Color Hydrogels

Structural color hydrogels with healable capability are of great significance in many fields, however the controllability of these materials still needs optimizing. Thus, this work presents a healable structural color hydrogel with photocontrolling properties. The component parts of the hydrogel are a graphene oxide (GO) integrated inverse opal hydrogel scaffold and a hydrogel filler with reversible phase transition. The inverse opal scaffold provides stable photonic crystal structure and the hydrogel filler is the foundation of healing. Taking advantage of the prominent photothermal conversion efficiency of GO, the healable structural color material is imparted with photocontrolled properties. It is found that the structural color hydrogel shaped in complex patterns can heal under near‐infrared (NIR) irradiation. These features indicate that the optical controllable healable structural color hydrogel can be employed in various applications, such as constructing complex objects, repairing tissues, and so on.     

2D simulation of the deformation of pH-sensitive hydrogel by novel strong-form meshless random differential quadrature method

The objective of presented work is to simulate the response of 2D hydrogel when subjected to the varying pH of buffer solution and initial fixed-charge concentration inside the hydrogel. The novelty of the work is that this is the first attempt to perform the 2D simulation of pH-responsive hydrogel by novel strong-form meshless method, such as random differential quadrature (RDQ) method. The analytical equations, derived for the hydrogel deformation in the x and y directions, are numerically verified by the square shaped hydrogel disc. The jumps in the distributions of ionic concentrations and electrical potential, across the interface between solution and hydrogel, are effectively captured by the RDQ method. A novel approach is proposed to correctly impose natural boundary conditions for non-uniform boundary. The effects of solution pH and initial fixed-charge concentration on the hydrogel swelling are also successfully investigated.     

聚乙烯醇水凝胶功能化改性研究进展

PVA水凝胶化学性质稳定、无毒、生物相容性好、耐生物老化、吸水量高及易于加工,广泛应用于固定化载体、药物释放、组织工程等领域。综述了当前国内外聚乙烯醇水凝胶的制备方法最新研究进展,详细介绍了国内外关于聚乙烯醇水凝胶的力学性能、溶胀性能、细胞亲和性、智能化等改性方法的研究进展。最后展望了未来聚乙烯醇水凝胶功能化改性的研究方向和前景。     

Polymersomes Containing a Hydrogel Network for High Stability and Controlled Release

Capillary microfluidic devices are used to prepare monodisperse polymersomes consisting of a hydrogel core and a bilayer membrane of amphiphilic diblock‐copolymers. To make polymersomes, water‐in‐oil‐in‐water double‐emulsion drops are prepared as templates through single‐step emulsification in a capillary microfluidic device. The amphiphile‐laden middle oil phase of the double‐emulsion drop dewets from the surface of the innermost water drop, which contains hydrogel prepolymers; this dewetting leads to the formation of a bilayer membrane. Subsequently, the oil phase completely separates from the innermost water drop, leaving a polymersome. Upon UV illumination of the polymersome, the prepolymers encapsulated within the interior are crosslinked, forming a hydrogel core. The hydrogel network within the polymersomes facilitates sustained release of the encapsulated materials and increases the stability of the polymersomes through the formation of a scaffold to support the bilayer. In addition, this approach provides a facile method to make monodisperse hydrogel particles directly dispersed in water.     

Transient modeling of the reversible response of the hydrogel to the change in the ionic strength of solutions

In this paper, a multi-effect-coupling ionic-strength-stimulus (MECis) model, which couples the mechanical, chemical and electrical effects on the swelling/shrinking of the smart hydrogel responsive to the ionic strength of the environmental solution, is presented for the transient analysis of the reversible kinetics of the ionic-strength-sensitive hydrogel. The MECis model is based on the laws of momentum and mass conservation, and considers the poroelasticity of the ionic-strength-sensitive hydrogel. In order to examine the model, the simulation results are compared with the experimental data with reversible swelling-shrinking kinetics, and they are in quite agreement. The reversible characteristics, including the mobile ions concentrations, the fixed charge density, the electric potential and the hydrogel displacement, are studied in order to fully understand the kinetics behavior of the ionic-strength-sensitive hydrogel.     

磁性水凝胶作为药物载体的应用研究进展

磁性水凝胶是一类同时具有磁性材料、高分子材料及水凝胶的性质特点的无机/有机复合材料。因具有优良的磁学性能及生物相容性,其作为新一代的药物载体可以实现磁响应、磁靶向及磁热疗等功能,在药物控制释放领域具有广阔的应用前景。对磁性水凝胶的制备方法及其在药物载体领域的研究情况进行了综述,详细介绍了磁性水凝胶作为药物载体的两种药物释放机理(ON/OFF模型及热敏释放原理),及其在磁靶向药物控释、磁热疗和磁共振成像方面的应用研究现状。     

Fabrication of nanozyme@DNA hydrogel and its application in biomedical analysis

Nanozymes have received great attention owing to the advantages of easy preparation and low cost.Unlike natural enzymes that readily adapt to physiological environments,artificial nanozymes are apt to passivate in complex clinical samples (e.g.,serum),which may damage the catalytic capability and consequently limit the application in biomedical analysis.To conquer this problem,in this study,we fabricated novel nanozyme@DNA hydrogel architecture by incorporating nanozymes into a pure DNA hydrogel.Gold nanoparticles (AuNPs)were adopted as a model nanozyme.Results indicate that AuNPs incorporated in the DNA hydrogel retain their catalytic capability in serum as they are protected by the hydrogel,whereas AuNPs alone totally lose the catalytic capability in serum.The detection of hydrogen peroxide and glucose in serum based on the catalysis of the AuNPs@DNA hydrogel was achieved.The detection limit of each reaches 1.7 and 38 μM,respectively,which is equal to the value obtained using natural enzymes.Besides the mechanisms,some other advantages,such as recyclability and availability,have also been explored.This nanozyme@DNA hydrogel architecture may have a great potential for the utilization of nanozymes as well as the application of nanozymes for biomedical analysis in complex physiological samples.     

D型Fmoc-苯丙氨酸/透明质酸复合双网络水凝胶的制备及应用

将N-芴甲氧羰基-D-苯丙氨酸(Fmoc-DPhe)和甲基丙烯酸缩水甘油酯(Glycidyl methacrylate,GMA)修饰的透明质酸(HA-GMA)在磷酸缓冲液中共混加热,冷却后Fmoc-DPhe分子先自组装形成超分子水凝胶,超分子水凝胶中的HA-GMA再经光照引发交联制备双网络复合水凝胶。研究该双网络水凝胶的力学性能、光学性质、微观形貌、药物缓释能力和抑菌性能。研究结果表明,双网络水凝胶比HA-GMA单网络水凝胶的力学性能强一倍左右且HA-GMA网络存在于双网络水凝胶中;光学性质显示双网络水凝胶中存在Fmoc-DPhe网络;微观形貌表明有两种水凝胶网络均存在于复合水凝胶中。当复合水凝胶包裹小分子模拟药物后,复合水凝胶达到模拟药物最大累积释放量的时间要比Fmoc-DPhe单网络水凝胶的长6 h;针对革兰氏阳性细菌的抑菌能力研究显示,双网络水凝胶的抑菌效果也比Fmoc-DPhe单网络水凝胶的更好。      

Biofriendly,Stretchable, and Reusable Hydrogel Electronics as Wearable Force Sensors

The ever‐growing overlap between stretchable electronic devices and wearable healthcare applications is igniting the discovery of novel biocompatible and skin‐like materials for human‐friendly stretchable electronics fabrication. Amongst all potential candidates, hydrogels with excellent biocompatibility and mechanical features close to human tissues are constituting a promising troop for realizing healthcare‐oriented electronic functionalities. In this work, based on biocompatible and stretchable hydrogels, a simple paradigm to prototype stretchable electronics with an embedded three‐dimensional (3D) helical conductive layout is proposed. Thanks to the 3D helical structure, the hydrogel electronics present satisfactory mechanical and electrical robustness under stretch. In addition, reusability of stretchable electronics is realized with the proposed scenario benefiting from the swelling property of hydrogel. Although losing water would induce structure shrinkage of the hydrogel network and further undermine the function of hydrogel in various applications, the worn‐out hydrogel electronics can be reused by simply casting it in water. Through such a rehydration procedure, the dehydrated hydrogel can absorb water from the surrounding and then the hydrogel electronics can achieve resilience in mechanical stretchability and electronic functionality. Also, the ability to reflect pressure and strain changes has revealed the hydrogel electronics to be promising for advanced wearable sensing applications.