淀粉基水凝胶的研究进展

淀粉是一种可再生的天然高分子,具有生物相容性好、可生物降解、无毒等优点,而水凝胶是具有吸水、保水性能的亲水聚合物网络。本文对近5年来淀粉基水凝胶的研究成果进行了归纳总结,以期为科研工作者提供淀粉基水凝胶的最新研究进展。文章分为如下部分：第一部分介绍了淀粉基水凝胶的研究背景;第二部分从淀粉基水凝胶的组成、形成原理、环境响应性等方面进行归纳总结;第三部分重点介绍了淀粉基水凝胶在水体净化、药物缓释、3D打印、农业和再生医学方面的应用。由此可知,目前淀粉基水凝胶在传感器、光电材料等方面的应用研究较少,同时其性能还不能够完全满足实际需求,因此科研工作者需进一步研究淀粉基水凝胶的结构与性能相互作用规律,完善淀粉基水凝胶的制备策略,拓展淀粉基水凝胶的应用范围,同时快速将其商品化及市场化,以产生巨大的经济效益与环境效益。     

生物质基水凝胶的传感应用进展

生物质材料是由动物、植物以及微生物等生命体衍生得到的材料,具备来源广泛、绿色安全、可再生和可生物降解等重要特征。生物质基水凝胶是以天然生物质大分子为原材料制备的水凝胶,已被广泛应用于污染物吸附、药物载体、生物工程以及多功能传感等领域。本文简要介绍了几种常见生物质基水凝胶的特点,包括基于蛋白质、纤维素、海藻酸盐、淀粉和壳聚糖等制备的水凝胶。同时,归纳了生物质基水凝胶在生物、应变、气体、湿度和温度等方面的最新传感应用。最后,结合目前研究现状,指出了生物质基水凝胶未来推广应用面临的挑战并提出了针对性解决思路。     

互穿网络聚合物水凝胶的制备及其吸附研究进展

互穿网络聚合物(IPN)水凝胶在分离技术领域具有广泛的应用前景,这些年受到人们广泛关注.本文介绍了聚多糖基(壳聚糖、海藻酸、淀粉和其他聚多糖)、蛋白质基(明胶、胶原蛋白、丝纤蛋白和大豆蛋白)和合成聚合物基(非离子型和离子型)IPN水凝胶的制备方法,主要包括同步-IPN、分步-IPN和半-IPN的制备方法.为了提高聚合物水凝胶的生物相容性、溶胀率和机械强度,采用天然高分子与合成高分子共混制备IPN水凝胶.与单网络水凝胶相比,IPN水凝胶对染料和重金属离子的吸附速率快、吸附容量大.为了达到选择性吸附和提高水凝胶的比表面积,制备离子印迹IPN水凝胶和多孔IPN复合冷冻凝胶,是未来研究高效吸附IPN水凝胶的发展方向之一.     

双网络水凝胶的研究进展

双网络水凝胶在保持高吸水性等性能的基础上改善了传统水凝胶机械性能差、不稳定等缺点.重点介绍了双网络水凝胶及其在组织工程、伤口敷料、离子吸附、农林业等方面的应用.当在组织工程、导电和伤口敷料等医学领域应用时,水凝胶的生物相容性及力学性能成为研究重点;当应用在林业和吸附染料、离子方面时,水凝胶的溶胀性能较为重要.     

纤维素基水凝胶的研究进展

纤维素是世界上最丰富的天然、可再生以及可生物降解的高分子材料,在化工、材料等领域有广泛的应用。本文主要对近几年来纤维素基水凝胶的研究进展进行了归纳总结。首先,介绍了纤维素基水凝胶的研究背景。其次,列举了纤维素水基凝胶的交联方法,主要有物理交联与化学交联。其中物理交联有氢键交联、疏水性交联、离子交联等,化学交联则是酯化交联、迈克尔加成、自由基共聚合、动态共价键交联等。最后,重点介绍了纤维素基水凝胶在可降解性、生物医学性、亲水性、吸附性、导电性等领域方面的应用。此外,对于纤维素基水凝胶材料在高机械性和产业化制备等方面的发展进行了展望。     

导电水凝胶的研究进展

导电水凝胶作为一种新型功能凝胶材料,受到了广大科研工作者的关注。本文总结了导电水凝胶的类型,分为聚电解质导电水凝胶、酸掺杂导电水凝胶、无机物填充导电水凝胶和导电高分子基导电水凝胶四大类。并综述其在柔性可穿戴电子产品、能源存储、能源转换及药物的可控释放等方面具有的应用前景。最后,对未来导电水凝胶的发展做了展望。     

温敏型分子印迹水凝胶的研究进展

近年来分子印迹技术发展迅速,以其高选择性、预定识别性等优点,在分离工程、化学传感器及模拟酶催化等领域均得到了广泛应用,但是其在水凝胶方面的研究却较少。将温敏水凝胶引入分子印迹技术制备温敏印迹水凝胶不仅能保持其特异识别性能,还赋予其对环境温度变化的响应性,使其对模板分子的识别具有温度可控性。本文简单介绍了温敏型分子印迹水凝胶的基本原理和制备方法,基于模板分子种类的不同,着重综述了温敏印迹凝胶在金属离子、有机小分子及生物蛋白方面的应用。同时对温敏印迹水凝胶的发展方向进行了展望,指出温敏印迹水凝胶将在物料分离、药物控释等领域表现出较好的应用前景。     

药物控释用智能水凝胶研究进展

智能水凝胶在药物控释方面具有智能化、效率高和安全方便等优点.近年来,研究开发药物控释用智能水凝胶非常活跃,展示了广阔的应用前景.本文综述了药物控释用温度、pH值、葡萄糖、电场、磁场及光敏感水凝胶的最新研究进展.     

湿化学法制备钛酸钡基粉体的研究进展

从反应机理、制备工艺及应用几方面出发,综述了钛酸钡基粉体的湿化学制备方法,包括溶胶-凝胶法、水热法、常压水相法和溶胶-凝胶水热法等,指出了这些方法的技术关键及优缺点,展望了湿化学法制备钛酸钡基粉体的发展前景。     

新型水凝胶基伤口敷料的研究进展

从结构特点、制备方法和性能效果等方面，综述了具有应用潜力的水凝胶基伤口敷料在近年来的国内外研究进展，包括海藻酸盐、壳聚糖、明胶、纤维素、羧甲基纤维素、聚乙烯醇和聚乙二醇，并对水凝胶基敷料的未来发展进行了展望。     

Tuning Strain Stiffening of Protein Hydrogels by Charge Modification

Strain-stiffening properties derived from biological tissue have been widely observed in biological hydrogels and are essential in mimicking natural tissues. Although strain-stiffening has been studied in various protein-based hydrogels, effective approaches for tuning the strain-stiffening properties of protein hydrogels have rarely been explored. Here, we demonstrated a new method to tune the strain-stiffening amplitudes of protein hydrogels. By adjusting the surface charge of proteins inside the hydrogel using negatively/positively charged molecules, the strain-stiffening amplitudes could be quantitively regulated. The strain-stiffening of the protein hydrogels could even be enhanced 5-fold under high deformations, while the bulk property, recovery ability and biocompatibility remained almost unchanged. The tuning of strain-stiffening amplitudes using different molecules or in different protein hydrogels was further proved to be feasible. We anticipate that surface charge adjustment of proteins in hydrogels represents a general principle to tune the strain-stiffening property and can find wide applications in regulating the mechanical behaviors of protein-based hydrogels.     

基于重组蛋白质的水凝胶

基于重组蛋白质的水凝胶在生物医学领域有广泛的潜在应用,因此这一领域在近20年吸引了研究工作者的极大研究热情并取得了巨大的进展。在这篇综述中,我们简要地讨论了基于重组蛋白质的水凝胶领域的最新进展,所涵盖的内容包括以生物识别为驱动力的物理交联的水凝胶以及化学交联的水凝胶的设计和构筑,以及它们在生物医学领域的应用。同时我们也讨论这一进展迅速的生物材料领域的发展前景与方向。     

Preparation and rheological investigation of tough PAAm hydrogel by adding branched polyethyleneimine

In this article, tough hydrogels are prepared by introducing the polyethyleneimine (PEI) with branched structure and a large number of  NH₂ and  NH groups into permanently crosslinked polyacrylamide (PAAm) hydrogels matrix. To investigate the effects of B-PEI and chemical crosslinking agent (Bis) on the strength and toughness of hydrogels, a series of B-PEI/PAAm hydrogels with different mass percentage of Bis and B-PEI were manufactured and the rheological and swelling properties were compared. For all hydrogels, the storage modulus (G′) was much higher than the loss modulus (G″) in the linear viscoelastic region through the whole frequency range. The solid-like behavior and elastic nature (G′ > G″) are attributed to the permanent covalence crosslinking. Therefore, G′ increased when more Bis was added. For the nonlinear oscillatory shear measurement, hydrogels with B-PEI broke at larger γ than the pure PAAm hydrogels, indicating that the toughness of B-PEI/PAAm hydrogels has been improved by introducing B-PEI. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48541.     

Reversible Control of Gelatin Hydrogel Stiffness by Using DNA Crosslinkers**

Biomaterials with dynamically tunable properties are critical for a range of applications in regenerative medicine and basic biology. In this work, we show the reversible control of gelatin methacrylate (GelMA) hydrogel stiffness through the use of DNA crosslinkers. We replaced some of the inter-GelMA crosslinks with double-stranded DNA, allowing for their removal through toehold-mediated strand displacement. The crosslinks could be restored by adding fresh dsDNA with complementary handles to those on the hydrogel. The elastic modulus (G’) of the hydrogels could be tuned between 500 and 1000 Pa, reversibly, over two cycles without degradation of performance. By functionalizing the gels with a second DNA strand, it was possible to control the crosslink density and a model ligand in an orthogonal fashion with two different displacement strands. Our results demonstrate the potential for DNA to reversibly control both stiffness and ligand presentation in a protein-based hydrogel, and will be useful for teasing apart the spatiotemporal behavior of encapsulated cells.     

Polypropylene oxide/polyethylene oxide-cellulose hybrid nanocomposite hydrogels as drug delivery vehicle

This article deals with the synthesis of hybrid nanocomposite hydrogels through the combination of cellulose (C), polypropylene oxide/poly ethylene oxide (PPO/PEO), and silver nanoparticles (AgNPs) by in situ polymerization technique for the in vitro release of ornidazole drugs. The structure of the resulted materials is identified using SEM, XRD, FTIR, XPS, and TGA spectroscopic techniques. The resulting structure, morphology, thermo responsive property, water retention, and swelling behavior of hydrogels are investigated. The rheological measurement is studied to establish the enhancement of the viscoelasticity and stiffness of hydrogels. The antibacterial activity of the biodegradable silver hybrid nanocomposite hydrogel is investigated by inhibition zone method against gram positive and negative bacteria. Maximum drug release of 96.4% is recorded at 7.4 pH in 5 h. The biocompatibility and cytotoxicity of the hybrid nanocomposite hydrogel are verified using mouse fibroblast cell line L-929 (ATCC CCL-1) cells for their possible use as controlled drug delivery vehicles. The nontoxic nature makes the materials more biocompatible and suitable to apply in the biological systems. Therefore, nontoxic and biocompatible natures of present materials with improved thermal and rheological properties support for their possible uses as drug delivery vehicles.     

Crosslinked poly(vinyl alcohol)/carboxymethyl chitosan hydrogels for removal of metal ions and dyestuff from aqueous solutions

Hydrogels composed of poly(vinyl alcohol) (PVA) and carboxymethyl chitosan (CMCh) were synthesized via ultraviolet (UV) irradiation that can be used in several industrial fields. Several analysis tools were used to characterize the physical and thermal properties of CMCh/PVA hydrogels namely FT‐IR, scanning electron microscope (SEM), XRD, thermogravimetric analysis (TGA), and differential scanning calorimetery (DSC). TGA results showed that CMCh/PVA hydrogels are thermally more stable than CMCh and their thermal stability increases as PVA content increases in the hydrogel. Also, DSC results showed that CMCh/PVA hydrogels are at least partial miscible blends. Moreover, the swelling behavior of the CMCh/PVA hydrogels was studied in different buffered solutions and in different salt solutions at various concentrations. CMCh/PVA hydrogels swell much more than CMCh especially at alkaline pH. Both metal and dye uptake were studied for CMCh/PVA hydrogels. The hydrogels adsorb much more dyestuff and metal ions like Cu²⁺, Cd²⁺, and Co²⁺ than CMCh itself. Much dyestuff and metal ions are adsorbed by the hydrogels as PVA content increases in the hydrogel. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermoresponsive hydrogels based on renewable resources

This work aims to synthesize novel thermoresponsive hydrogels from renewable resources, bacterial cellulose (BC), and castor oil (CO), and to investigate the effect of CO on physical and thermal behaviors of BC/Poly(N-isopropylacrylamide) (PNIPAM) hydrogels. The structural properties of the hydrogels are analyzed by Fourier-transform infrared (FTIR) spectroscopy. Differential scanning calorimeter (DSC) technique and thermogravimetric analysis (TGA) are also performed to examine the thermal properties of the hydrogels. The morphological differences of the hydrogels are analyzed by scanning electron microscope (SEM). The thermoresponsive performances of the hydrogels are examined by swelling and deswelling behaviors. The hydrogel with CO is found to be more sensitive to temperature changes than the one without CO. Deswelling study demonstrates 91 and 25% of water loss for hydrogels with and without CO, respectively. The present study shows a novel approach to synthesize thermoresponsive hydrogels with renewable resources for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48861.     

Preparation and characterization of chitosan based hydrogels containing cyclodextrin inclusion compounds or nanoemulsions of thyme oil

Hydrogels derived from natural polysaccharides are ideal scaffolds for use in biomedical applications. pH‐sensitive polyvinyl alcohol and chitosan hydrogels containing inclusion compounds of thyme oil (TM) with host methyl‐β‐cyclodextrin (MβCD) and hydroxypropyl‐β‐cyclodextrin (HβCD) and TM nanoemulsion (TM‐nano) were prepared via controlled, biocompatible and low cost freeze–thaw method. The structure of the hydrogels was characterized by Fourier transform IR spectroscopy and optical and scanning electron microscopy. The physicochemical properties of the hydrogels such as gel fraction, swelling ratio and tensile properties were measured. The water vapor transmission rate of the hydrogels indicated that they can maintain a moist environment over the wound bed. Encapsulation and release of antibacterial TM from the hydrogels were determined by UV spectroscopy. In all cases, hydrogels with lower amounts of TM evidenced slower and more controlled release. Different kinetic models were applied for evaluating the drug release mechanism. The antibacterial activity of the samples was studied by counting the number of both Gram‐negative and Gram‐positive bacteria surviving in a broth medium and the results proved the antibacterial activity of all prepared hydrogels. The results of an MTT (3‐(4,5‐dimethylthiazol‐2yl)‐2,5‐diphenyltetrazolium bromide) assay indicated more cell viability of TM‐nano hydrogels in comparison with those of TM‐βCD inclusion compounds. Cell attachment observations also showed great biocompatibility of TM‐nano hydrogels. The prepared hydrogels, especially those containing TM‐nano, might be used as potential wound dressings to improve the wound healing process. © 2019 Society of Chemical Industry     

温度及pH敏感生物水凝胶的研究

运用互穿网络技术,合成了具有温敏性的聚(N 异丙基丙烯酰胺)(PNIPAm)和生物大分子明胶(gelatin)的互穿网络聚合物(PNIPAm/Gelatinsemi IPN和PNIPAm/GelatinIPN)水凝胶,该水凝胶的最低临界溶液温度(LCST)与PNIPAm水凝胶的LCST基本相同,均为33℃左右,但在LCST以下的平衡溶胀率减小、相变区域略微变宽。在此基础上,通过N 异丙基丙烯酰胺(NIPAm)与丙烯酸(AAc)交联共聚,改变了水凝胶的LCST,在pH=4 0的缓冲溶液中,各水凝胶的溶胀行为基本一致,与AAc含量无关,LCST都为28℃左右;在pH>4 0的缓冲溶液中,LCST随AAc组分含量的增加而增加,但温敏性减小。同时,AAc的加入,使水凝胶具有pH敏感性,敏感点为pH=4 5左右。还考察了该水凝胶降解的特点:戊二醛(GA)交联后的明胶网络,保留了明胶的生物降解性,但互穿网络水凝胶在实验条件下几乎未被胃蛋白酶和胰蛋白酶降解,在pH=9 6的碱性条件下,水凝胶可发生化学降解。     

Protein-Based Nanoparticle Vaccines for SARS-CoV-2

The pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has upended healthcare systems and economies around the world. Rapid understanding of the structural biology and pathogenesis of SARS-CoV-2 has allowed the development of emergency use or FDA-approved vaccines and various candidate vaccines. Among the recently developed SARS-CoV-2 candidate vaccines, natural protein-based nanoparticles well suited for multivalent antigen presentation and enhanced immune stimulation to elicit potent humoral and cellular immune responses are currently being investigated. This mini-review presents recent innovations in protein-based nanoparticle vaccines against SARS-CoV-2. The design and strategy of displaying antigenic domains, including spike protein, receptor-binding domain (RBD), and other domains on the surface of various protein-based nanoparticles and the performance of the developed nanoparticle-based vaccines are highlighted. In the final part of this review, we summarize and discuss recent advances in clinical trials and provide an outlook on protein-based nanoparticle vaccines.