智能型水凝胶

智能型水凝胶是一类具有广泛应用前景的功能高分子材料，但由于传统水凝胶存在一些缺点因而限制了其应用，因此近年来围绕提高传统水凝胶的性能做了大量研究工作。本文从四个主要方面综述了近年来智能型水凝胶改性的研究进展。     

水凝胶功能改性研究与应用进展

水凝胶是一种三维网状亲水性高分子软材料,具有良好的固体力学和液体热力学性能,其自身柔软、可塑性强、生物相容性好,具有可降解性和刺激性响应特征。但传统方法制备的水凝胶有诸多缺陷,如有毒性、生物活性低、机械性能差等,使得其应用受限。本文综述了近10年来功能水凝胶制备与改性的主要研究进展及其应用现状,以多吸收位点和高机械强度等性能为主,重点阐述了国内外功能性水凝胶的最新制备方法,包括物理改性中的低分子复合材料交联与构建多重网络和化学改性中的接枝共聚等。详细介绍了该类功能材料在医药、生物、农业和食品等方面的应用现状与发展前景,特别关注了高效短时对外界环境微小变化具有响性的智能印迹水凝胶及其在检测领域的应用,为水凝胶的进一步开发和推广应用提供参考。     

光交联水凝胶材料的研究与生物医学应用进展

光交联制备水凝胶技术具有非物理接触以及时空精确可控等优势,在细胞3D培养/打印以及组织工程和再生医学领域具有广阔的应用前景.当前,光交联水凝胶的制备主要基于光引发自由基交联反应、光点击交联反应或光偶联交联反应.本文分别介绍了以上交联反应各自的技术发展史、应用现状以及相关的优势和技术瓶颈.还着重介绍了本课题组在光交联水凝胶领域开展的研究与转化工作,主要包括提出了利用光笼分子的光剪切释放活性基团触发偶联交联的非自由基光交联策略,即光偶联反应交联策略.该策略实现了光交联水凝胶的低毒、可控构筑,同时赋予了光交联水凝胶技术的原位组织黏附特性,为该技术的最终临床转化奠定了基础.     

海藻酸钠水凝胶的制备及其在药物释放中的应用

近年来,由于智能水凝胶在药物的控制释放、基因传送、组织工程等领域的应用前景诱人,研究者对智能水凝胶的研究十分活跃。合成类水凝胶常用的单体有丙烯酸及其衍生物、丙烯酰胺及其衍生物等,合成水凝胶具有较好的稳定性,但其生物降解性和生物相容性较差。天然类水凝胶的原料主要有壳聚糖、海藻酸钠、纤维素、淀粉等。由于这些天然多糖具有较好的生物相容性和生物降解性,同时价廉易得,因此,天然类水凝胶在药物控制释放领域更具有优势。海藻酸钠是β-D-甘露糖醛酸(β-D-mannuronic,M)和α-L-古洛糖醛酸(α-L-guluronic,G)按照(1→4)糖苷键连接而成的线型聚合物,每个糖醛酸单元上含有一个羧基,因此,海藻酸钠在中性或碱性条件下呈现聚阴离子电解质的性质。本文综述了海藻酸钠水凝胶的制备方法,包括物理交联法、化学交联法、酶交联法、互穿聚合物网络等;概述了海藻酸钠水凝胶在药物释放中的应用,包括口服给药、皮下给药、黏膜给药、肺部给药、经皮给药等;最后讨论了海藻酸钠水凝胶在研究与应用中存在的问题。     

医用高分子水凝胶的设计与合成

作为一类重要的医用功能材料,高分子水凝胶可望在药物控释、软骨支架构建、活性细胞封装等方面获得广泛应用。综述了基于化学交联和物理交联的有关水凝胶的设计与合成方法,重点介绍了通过自由基共聚反应、结构互补基团间化学反应形成的化学交联水凝胶以及通过荷电相反离子问相互作用、两亲性嵌段或接枝共聚物疏水缔合、结晶与氢键相互作用形成的物理交联水凝胶。     

水凝胶材料在类器官研究中的应用进展

类器官指通过干细胞自组织在体外三维(3D)培养条件下分化形成的功能性细胞组织复合体,能够反映人体来源组织或器官的部分关键结构和功能特征,是一种极具前景的体外模型体系.目前,多数类器官的形成和培养都依赖复杂的动物来源细胞外基质(如Matrigel),该类基质的肿瘤源性和批次差异性影响了类器官培养的重现性,难以满足生物医学研究的需求.相比之下,各种天然和合成基水凝胶成分明确,具有高度可调的物理和化学特性,已广泛用于各种细胞的3D培养.本文概述了类器官的形成与培养现状,重点介绍了各种已用于类器官研究的水凝胶材料及其设计与工程化策略,讨论了功能化水凝胶材料在类器官基础研究和转化应用方面的潜力,并对其未来的发展趋势与面临挑战进行了展望.     

含有锂皂土/聚多巴胺复合纳米微粒的再生丝蛋白水凝胶

在辣根过氧化物酶/过氧化氢酶促交联(化学交联)制备再生丝蛋白化学交联凝胶的过程中,通过引入锂皂土/聚多巴胺复合纳米材料作为第二组分,以调节反应并提高化学交联效率;再经乙醇熟化后,再生丝蛋白化学交联凝胶中可进一步形成物理网络,进而得到双交联凝胶.结果表明,第二组分的引入不仅能够提高再生丝蛋白化学交联水凝胶的力学性能,并有利于后续均匀物理交联网络的形成,致使最终所得双交联水凝胶具有更好的力学性能.同时,由此制备的双交联水凝胶传承了再生丝蛋白良好的生物相容性以及与交联结构密切相关的生物降解性,并具备了诱导干细胞成骨分化的能力,因而在软骨修复等领域具有潜在的应用价值.     

两性离子水凝胶的制备及生物医学应用

两性离子水凝胶是一类含有两性离子聚合物的凝胶材料,其分子结构中的阴阳离子基团能与水分子紧密结合,形成致密的水合层。这种静电诱导水合作用使得两性离子水凝胶具有极低的生物黏附性,能有效抵抗非特异性蛋白、细胞、细菌等的黏附,具有极低的免疫原性。这些特性使得两性离子水凝胶在生物医用领域有广阔的应用前景。本综述首先介绍了两性离子水凝胶的结构及性质,然后概述了其分类和制备方法,并进一步总结了其在组织工程、药物载体、创伤敷料、生物传感器、医疗器械水凝胶涂层等生物医学领域中的应用。最后展望了两性离子水凝胶未来的发展方向。     

交联聚乙烯醇水凝胶对胆红素的吸附性能研究

本文采用反相聚合的方法以戊二醛为交联剂合成了珠状交联聚乙烯醇凝胶，并研究了它对胆红素的吸附性能。结果表明交联聚乙烯醇对胆红素的体外吸附率受到吸附剂的交联度、颗粒直径、溶液中白蛋白的浓度、吸附温度及离子强度的影响。该类吸附剂对胆红素具有良好的吸附动力学性能。     

Lanthanide-containing photoluminescent materials: from hybrid hydrogel to inorganic nanotubes

Functional photoluminescent materials are emerging as a fascinating subject with versatile applicability. In this work, luminescent organic-inorganic hybrid hydrogels are facilely designed through supramolecular self-assembly of sodium cholate, and lanthanide ions such as Eu(3+), Tb(3+), and Eu(3+)/Tb(3+). Fluorescence microscopy and TEM visualization demonstrates the existence of spontaneously self-assembled nanofibers and 3D networks in hybrid hydrogel. Photoluminescence enhancement of lanthanide ions is realized through coordination with cholate and co-assembly into 1D nanofibers, which can successfully shield the Eu(3+) from being quenched by water. The photoluminescence emission intensity of a hybrid hydrogel exhibits strong dependence on europium/cholate molar ratio, with maximum emission appearing at a stoichiometry of 1:3. Furthermore, the emission color of a lanthanide-cholate hydrogel can be tuned by utilizing different lanthanide ions or co-doping ions. Moreover, photoluminescent lanthanide oxysulfide inorganic nanotubes are synthesized by means of a self-templating approach based on lanthanide-cholate supramolecular hydrogels. To the best of our knowledge, this is the first time that the lanthanide oxysulfide inorganic nanotubes are prepared in solution under mild conditions.     

Synthesis and properties of a novel double network nanocomposite hydrogel

A novel polyacrylamide/polyacrylic acid (PAAm/PAA) double network (DN) nanocomposite (NC) hydrogel had been synthesized by two‐step solution polymerization. The PAAm network was crosslinked by inorganic clay while the PAA network was crosslinked by a chemical crosslinker. The chemical structure of the network was confirmed by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and transmission electron microscopy (TEM). The swelling and mechanical strength properties of PAAm/PAA hydrogels were examined. The results showed that a DN hydrogel achieved both a high swelling capacity of 1219 g/g in deionized water and 124 g/g in 0.9 wt% NaCl solution and high compressive stress of 21.5 kPa in a high water content of 99.58%. Copyright © 2008 John Wiley & Sons, Ltd.     

Structures and antifouling properties of low surface energy non-toxic antifouling coatings modified by nano-SiO_2 powder

Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing or- ganisms, such as barnacles and weed, building up on the underwater hull and helping the ships movement through the water. Typically, marine coatings are tributyltin self-polishing copolymer paints containing toxic molecules called biocides. They have been the most successful in combating bio- fouling on ships, but their widespread use has caused severe pollution in the marine ecosystem. The low surface energy marine coating is an entirely non-toxic alternative, which reduces the adhesion strength of marine organisms, facilitating their hydrodynamic removal at high speeds. In this paper, the novel low surface energy non-toxic marine antifouling coatings were prepared with modified acrylic resin, nano-SiO2, and other pigments. The effects of nano-SiO2 on the surface structure and elastic modulus of coating films have been studied, and the seawater test has been carried out in the Dalian Bay. The results showed that micro-nano layered structures on the coating films and the lowest surface energy and elastic modulus could be obtained when an appropriate mass ratio of resin, nano-SiO2, and other pigments in coatings approached. The seawater exposure test has shown that the lower the sur- face energy and elastic modulus of coatings are, the less the marine biofouling adheres on the coating films.     

Slow release of wound healing drug from hydrogel wound dressing prepared by radiation crosslinking method

The hydrogel wound dressing was prepared by radiation crosslinking. It was used of on patients in the Navy 411 Hospital and some other hospitals. From sixty case studies of the clinical effects, the results showed that: 1. drug releasing slowly releives the pain effectively for prolonged period of application; 2. The dressing can reduce the oozing liquid from the wound and make the wound heal faster; 3. The number of the dressing change is greatly reduced. All the data indicates that the dressing is superior to the conventional kinds.     

Structures and antifouling properties of low surface energy non-toxic antifouling coatings modified by nano-SiO<Subscript>2</Subscript> powder

Antifouling coatings are used to improve the speed and energy efficiency of ships by preventing organisms, such as barnacles and weed, building up on the underwater hull and helping the ships movement through the water. Typically, marine coatings are tributyltin self-polishing copolymer paints containing toxic molecules called biocides. They have been the most successful in combating biofouling on ships, but their widespread use has caused severe pollution in the marine ecosystem. The low surface energy marine coating is an entirely non-toxic alternative, which reduces the adhesion strength of marine organisms, facilitating their hydrodynamic removal at high speeds. In this paper, the novel low surface energy non-toxic marine antifouling coatings were prepared with modified acrylic resin, nano-SiO₂, and other pigments. The effects of nano-SiO₂ on the surface structure and elastic modulus of coating films have been studied, and the seawater test has been carried out in the Dalian Bay. The results showed that micro-nano layered structures on the coating films and the lowest surface energy and elastic modulus could be obtained when an appropriate mass ratio of resin, nano-SiO₂, and other pigments in coatings approached. The seawater exposure test has shown that the lower the surface energy and elastic modulus of coatings are, the less the marine biofouling adheres on the coating films. Supported by High-Tech Research and Development Program of China (Grant No. 2004AA001520)     

Radiation preparation and thermo-response swelling of interpenetrating polymer network hydrogel composed of PNIPAAm and PMMA

Interpenetrating polymer network (IPN) hydrogel composed of hydrophilic poly(N-isopropylacrylamide) (PNIPAAm) and hydrophobic poly(methyl methacrylate) (PMMA) were synthesized by sequential IPN method using γ-rays from ⁶⁰Co source. Compared with pure PNIPAAm hydrogel, PNIPAAm/ PMMA IPN hydrogel not only behaved with obvious temperature sensitivity, but also had higher mechanical strength. The shrinking rate of the prepared IPN hydogel was slower than that of PNIPAAm hydrogel and the relative shrinkage was higher than that of PNIPAAm hydrogel. The IPN hydrogel with less PMMA was not stable while with more PMMA it was quite stable. In addition, the release of Methylene Blue (MB) from the IPN hydrogel was slower than that from PNIPAAm hydrogel as well.     

Surface‐dependent effect of functional silica fillers on photocuring kinetics of hydrogel materials

Two types of silica: precipitated (P, prepared in non‐polar media, a new type, submicrometer sized) and fumed (F, nanosized), both unmodified and surface modified are investigated as functional fillers for potential applications in nanocomposites with poly(2‐hydroxyethyl methacrylate) matrix. Special attention is paid to the kinetics of composite formation in an in situ photopolymerization process. Silica‐containing formulations polymerize faster; this effect is much stronger for silica P having much larger particle size than silica F. Surface treatment leads to further acceleration of the polymerization in case of silica P but to retardation in case of silica F; the effect of modification of the filler surface on properties of composites is different for each of the silicas. The obtained results are discussed in terms of effects of curvature of silica particles, surface properties, solvation cell, interphase region, viscosity changes, and morphology of the resulting composites. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3472–3487     

Synthesis and thermal properties of a novel lactose‐containing poly(N‐isopropylacrylamide‐co‐acrylamidolactamine) hydrogel

An improved, simple, and efficient method for the synthesis of lactose‐containing monomer acrylamidolactamine (LAM) has been reported. Free radical copolymerization of this monomer with N‐isopropylacrylamide (NIPAM) in the presence of the crosslinking reagent N,N′‐methylenebisacrylamide (BisA) (1.2 mol %) proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) as the initiating system and gave transparent hydrogels. Reactivity ratios were estimated from copolymerization reactions carried out in solution without BisA crosslinker and at low conversion, by using both linearization and nonlinearization methods. They were found to be r_LAM = 0.75 and r_NIPAM = 1.22. The swelling behavior of the hydrogels was studied by immersion of the hydrogels in deionized water at different temperatures. Equilibrium water uptake was increased when the LAM content was higher than 47 mol %, and reached ≈ 44‐fold with 100 mol % LAM at room temperature. Depending on the composition, the gels showed sharp swelling transitions with small changes in temperature. Differential scanning calorimetry (DSC) was used to characterize the swelling transition and the organization of water in the copolymer hydrogels. The amounts of freezable water in these hydrogels ranged from 81 to 89%, and was not correlated to the content of the sugar monomer. These gels have potential applications as biocompatible materials. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1393–1402, 1999     

Effect of thermal annealing on a bilayer polyvinyl alcohol/polyacrylic acid electrospun hydrogel nanofibres loaded with doxorubicin and clarithromycin for a synergism effect against osteosarcoma cells

Polyvinyl alcohol/polyacrylic acid (PVA/PAA) bilayer hydrogel nanofibres were successfully fabricated by electrospinning and physically crosslinked via heat treatment. The effects of the thermal annealing process on the structure, morphology, swelling, thermal properties and hydrophilicity of electrospun nanofibres were investigated. In addition, these membranes were also used to incorporate doxorubicin and clarithromycin for osteosarcoma treatment, one in each layer. These drugs were used because it is hypothesized in this work that a synergism occurs between both drugs. So, these membranes were analyzed towards their dual-drug release and potential cytotoxicity towards the U2OS human osteosarcoma cell line. Moreover, the water contact angle, disintegration, swelling and weight loss studies confirmed the rapid swelling and improved water stability of the annealed PVA/PAA bilayer nanofibres. The annealed bilayer nanofibres exhibited an increase in the average diameter and degree of crystallinity. In addition, the results revealed that a variation occurred in the degree of hydrophilicity of annealed PVA/PAA bilayer nanofibres. The PAA nanofibres surface exhibited higher hydrophilicity than the PVA nanofibres surface. Drug delivery presented to be as fast rate release for clarithromycin and slow-rate release for doxorubicin, which may be advantageous because both drugs exhibited to be synergetic for certain dosages presenting the combination of the drugs higher than 50% of cell inhibition, while these membranes had higher inhibition values (up to 90%), which was attributed to the PAA but also the drugs. These unique properties are of potential interest in drug delivery applications for dual drug delivery where the tunability of surfaces is desirable.     

Novel organic–inorganic hybrid materials from renewable resources: Hydrosilylation of fatty acid derivatives

Novel hybrid organic–inorganic materials were prepared from 10‐undecenoyl triglyceride and methyl 3,4,5‐tris(10‐undecenoyloxy)benzoate via hydrosilylation. 1,4‐Bis(dimethylsilyl)benzene, tetrakis(dimethylsilyloxy)silane, and 2,4,6,8‐tetramethylcyclotetrasiloxane were used as crosslinkers. The hydrosilylation reaction was catalyzed by Karstedt's catalyst [Pt(0)–divinyltetramethyldisiloxane complex]. The networks were structurally characterized by Fourier transform infrared spectroscopy, ¹³C NMR, and ²⁹Si magic‐angle‐spinning NMR. The thermal properties of these hybrids were studied with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The obtained materials showed good transparency and promising properties for optical applications. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6295–6307, 2005