可注射原位凝胶的制备及性能表征

以聚琥珀酰亚胺(PSI)为原料,利用酰亚胺基开环反应,首先制备得到α,β-聚(N-羟乙基)-DL-天门冬酰胺(PHEA),再与丙烯酰氯反应,制备得到接枝丙烯酰胺基α,β-聚(N-羟乙基)-DL-天门冬酰胺(PHA).通过FT-IR、NMR对其结构进行了表征.这种大分子单体的溶液可在人体温度下发生原位的交联反应,形成凝胶.可通过改变接枝率、大分子单体浓度等因素控制凝胶化时间.当选用质量浓度为0.1g/mL的PHA1#(接枝率为19.6%)单体、交联剂质量浓度为4mg/mL、引发剂浓度为20mmol/L时,凝胶化时间为90s.该凝胶具有可注射性和疏松的大孔结构,并且凝胶化时间可控,在模拟体液中有轻微溶胀,是较理想的治疗干眼症注射式材料.     

原子转移自由基聚合方法制备的半纤维素基水凝胶及其性能

以传统稀碱抽提法从农业废弃物——玉米芯中分离出的半纤维素为原料,采用原子转移自由基聚合方法(ATRP),通过控制反应条件,将具有温度响应特性的N-异丙基丙烯酰胺(NIPAM)和交联功能单体二甲基丙烯酸乙二醇酯(EDG)引入上述聚合物侧链中,制备出具有PNIPAM链段和不饱和双键封端侧链的半纤维素衍生物,经紫外光辐照交联成功制备出新型半纤维素基水凝胶。研究结果表明,这种半纤维素基水凝胶具有显著的温度负响应特性。此外,水凝胶的温度响应特性以及溶胀/消溶胀行为还受到聚合物的交联度、接枝共聚物原料组成以及功能单体添加量等因素的影响。     

交联方式对半乳糖基温敏凝胶结构和性能的影响

为改善传统化学交联水凝胶的低力学性能、透明度、溶胀度和生物相容性, 以无机纳米粒子硅酸镁锂(LMSH)作为物理交联剂, 半乳糖氨基化的丙烯酸衍生物(GAC)作为生物相容性单体, N-异丙基丙烯酰胺(NIPAM)为功能单体, 采用原位自由基聚合制备得到兼具温度敏感性和生物相容性的纳米复合水凝胶poly(NIPAM-LMSH-GAC)。结果表明: LMSH在水凝胶基体中被完全剥离, 并起到交联作用; 相比于传统化学交联剂制备的此类水凝胶, 所得物理交联的纳米复合水凝胶具有更高的溶胀度、良好的温敏性、优异的脉冲响应性, 但鼠成纤细胞(L929)在纳米复合水凝胶表面的细胞数量略低; 物理交联剂LMSH的使用和一定量的GAC的使用并没有明显改变水凝胶的体积相转变温度(VPTT), 仍保持在33℃左右。     

交联方式对半乳糖基温敏凝胶结构和性能的影响

为改善传统化学交联水凝胶的低力学性能、透明度、溶胀度和生物相容性,以无机纳米粒子硅酸镁锂(LMSH)作为物理交联剂,半乳糖氨基化的丙烯酸衍生物(GAC)作为生物相容性单体,N-异丙基丙烯酰胺(NIPAM)为功能单体,采用原位自由基聚合制备得到兼具温度敏感性和生物相容性的纳米复合水凝胶poly(NIPAM -LMSH-GAC).结果表明:LMSH在水凝胶基体中被完全剥离,并起到交联作用;相比于传统化学交联剂制备的此类水凝胶,所得物理交联的纳米复合水凝胶具有更高的溶胀度、良好的温敏性、优异的脉冲响应性,但鼠成纤细胞(L929)在纳米复合水凝胶表面的细胞数量略低;物理交联剂LMSH的使用和一定量的GAC的使用并没有明显改变水凝胶的体积相转变温度(VPTT),仍保持在33℃左右.     

pH-GSH双敏感型P(mPEGMA-DEAM-SS)水凝胶的溶胀动力学

以甲氧基聚乙二醇甲基丙烯酸酯(m PEGMA)、甲基丙烯酸-N-N-二乙氨基乙酯(DEAM)为单体,2,2'-二硫二乙醇的二甲基丙烯酸酯(SS)为交联剂,采用自由基交联共聚法制备了具有p H-GSH双敏感性的P(m PEGMA-DEAM-SS)水凝胶。研究了溶剂对凝胶溶胀性能的影响,并初步研究了在不同介质中水凝胶的溶胀动力学。结果表明,以N-N-二甲基甲酰胺(DMF)为溶剂时,可获得良好p H响应能力的水凝胶;水凝胶的溶胀过程表现出良好的p H-GSH双敏感性,该水凝胶的扩散行为在酸性介质中符合non-Fickian模型,而在中性介质则符合Fickian模型;在10 mmol/L GSH条件下,水凝胶溶胀率上升了4倍多,其扩散亦为non-Fickian扩散模式。     

多孔聚合物水凝胶的合成及正渗透性能

为了提高聚N-异丙基丙烯酰胺-丙烯酸钠(PNIPAM-PSA)水凝胶汲取剂的正渗透性能,加入致孔剂聚乙二醇(PEG),通过交联聚合法制备了多孔聚N-异丙基丙烯酰胺-丙烯酸钠(PNIPAM-PSA)水凝胶汲取剂。采用红外光谱、扫描电镜等测试方法对其进行了表征,并研究了水凝胶汲取剂的溶胀率、脱水率、水通量和再生性能。结果表明,加入致孔剂PEG(400)后,水凝胶的表面呈多孔结构;当PEG(400)与单体摩尔比为1∶2时,所制备的多孔水凝胶性能最好,与PNIPAM-PSA水凝胶相比,其溶胀率、脱水率和正渗透水通量分别提高了162.26%,15.08%和144.44%;再生的水凝胶,正渗透性能稳定。     

半纤维素的提取及其温敏性水凝胶的制备

以采用稀碱抽提法从植物残料中提取的半纤维素为原料,通过化学交联法,自由基聚合将单体接枝到半纤维素链上,并交联温敏性单体,促使形成共聚交联网络结构,得到温度敏感性水凝胶。通过物理交联法,半纤维素与壳聚糖物理交联,制备半纤维素基水凝胶。采用交联度测定、溶胀动力学研究、红外光谱、差示量热等手段对化学交联和物理交联两种方法制得的半纤维素基水凝胶温度响应性能进行表征。结果表明:10%NaOH提取的半纤维素得率最高;化学交联法和物理交联法制得的半纤维素基水凝胶,都具有温度负响应特性,为温敏性水凝胶。作为当下较为热门材料,广泛应用于医疗、农业和生物组织工程材料等领域。     

聚乙二醇双丙烯酸酯的紫外光聚合

以1-[4-(2-羟乙氧基)-苯基]-2-羟基-2甲基丙酮为光引发剂,通过紫外光自由基聚合制备了交联网状聚乙二醇双丙烯酸酯共聚物水凝胶。研究结果表明,随着光照时间的增加,单体共聚的转化率提高;随着引发剂浓度的增大,单体溶液中自由基增多,聚合速度增大。FI-IR结果表明PEGDA单体经30min紫外光照射后聚合完全。     

聚乙烯醇大分子单体及其功能微球的制备

由氨基乙醛二甲基缩醛与丙烯酰氯反应得到N-丙烯酰胺基乙醛二甲基缩醛(NAAADA),在酸性介质中使其与聚乙烯醇(PVA)发生缩醛交换反应,制得了PVA大分子单体(PVA-NAAADA)。用傅里叶红外(FT-IR)、核磁共振(1 H-NMR)对PVA-NAAADA的化学结构进行表征;并以制备的PVA-NAAADA及2-丙烯酰胺-2-甲基丙磺酸(AMPS)为共聚单体,经反相悬浮法制备了具有pH敏感性的交联型PVA功能微球,通过光学显微镜观察了微球的大小与形貌。结果表明:所制备的微球粒径较均一,单分散性良好,在pH=7.0的缓冲溶液中对5-氟尿嘧啶的释药率最大可达到72.3%,具有显著的pH敏感性。     

化学/离子交联水凝胶的透光度溶胀行为和力学性能EI北大核心CSCD

以丙烯酰胺(AM)和海藻酸钠(SA)为功能单体,N,N'-亚甲基双丙烯酰胺(MBA)和CaCl2为交联剂,制备得到化学/离子复合交联水凝胶(CIC型),同时合成出化学交联(CC)、离子交联(IC)和半互穿化学交联(SCC)型水凝胶作为对比,采用紫外可见分光光度计、场发射扫描电镜、称重仪和单纤维强力机对4种水凝胶的透光度、孔洞结构、溶胀行为和力学性能进行了研究。结果表明,CC型水凝胶的吸光度值为0.049,透光性最好,透光性由好及坏顺序为CC>SCC>CIC>IC;CIC方式制得的水凝胶吸光度为0.621;最大断裂应力为158.9 kPa,分别是CC型和SCC型水凝胶的5.17倍和1.96倍;最大拉伸倍数和最大溶胀比(MSR)为4.29 g/g和13.70 g/g,分别是IC型水凝胶的9.77倍和12.38倍;场发射扫描电镜结果表明CIC水凝胶具有海绵状规整的微孔结构,是用于替代肌腱组织的理想材料。     

Cell-laden photocrosslinked GelMA–DexMA copolymer hydrogels with tunable mechanical properties for tissue engineering

To effectively repair or replace damaged tissues, it is necessary to design three dimensional (3D) extracellular matrix (ECM) mimicking scaffolds with tunable biomechanical properties close to the desired tissue application. In the present work, gelatin methacrylate (GelMA) and dextran glycidyl methacrylate (DexMA) with tunable mechanical and biological properties were utilized to prepared novel bicomponent polymeric hydrogels by cross-linking polymerization using photoinitiation. We controlled the degree of substitution (DS) of glycidyl methacrylate in DexMA so that they could obtain relevant mechanical properties. The results indicated that copolymer hydrogels demonstrated a lower swelling ratio and higher compressive modulus as compared to the GelMA. Moreover, all of the hydrogels exhibited a honeycomb-like architecture, the pore sizes decreased as DS increased, and NIH-3T3 fibroblasts encapsulated in these hydrogels all exhibited excellent viability. These characteristics suggest a class of photocrosslinkable, tunable mechanically copolymer hydrogels that may find potential application in tissue engineering and regenerative medicine applications.     

可生物降解聚天冬氨酸水凝胶的合成及性能

采用两步交联法合成了可生物降解聚天冬氨酸水凝胶。首先用赖氨酸作为内交联剂对聚丁二酰亚胺进行开环反应,以侧基的形式引入聚合物链中,然后用戊二醛为表面交联剂进行进一步交联反应,从而形成水凝胶。研究了反应温度、时间、赖氨酸及戊二醛用量对水凝胶溶胀性能的影响。并对水凝胶的溶胀机理进行了初步的探讨,结果表明,溶胀过程属于非Fickian扩散。pH敏感性测试表明水凝胶在pH=3.4时收缩,而在pH<3.4和pH>3.4时溶胀,且在中性和碱性条件下的溶胀率大于在酸性条件下的溶胀率。     

半纤维素基水凝胶制备及应用研究进展

半纤维素基水凝胶是一种具有优异保水性、良好生物相容性和力学性能的三维网络状亲水聚合物,在软材料领域尤其是半纤维素基材料研究领域备受瞩目。本文综述了近年来半纤维素基水凝胶的研究进展,从化学交联和物理交联两个方面介绍了半纤维素基水凝胶的制备方法、形成机理和性能,比较了化学交联中光、酶、微波辐射和辉光放电电解等离子体等不同引发体系的差异,总结了半纤维素基水凝胶在药物控释、伤口敷料、高效吸附及3D打印等领域的最新应用和发展,并对半纤维素基水凝胶领域所面临的挑战进行了总结和展望,以期为新型半纤维素水凝胶的研究提供参考。     

温度/pH敏感性壳聚糖-聚乙烯吡咯烷酮水凝胶的制备

以壳聚糖（CS）和聚乙烯基吡咯烷酮（PVP）为原料,戊二醛为交联剂,硝酸铈铵为引发剂,制备了具有温度和pH双重敏感性的CS/PVP水凝胶。考察了制备条件对水凝胶溶胀率的影响,结果表明,在PVP∶CS（质量比）=10∶1,0.3%（质量分数,下同）交联剂（相对于PVP）,2.5%引发剂,60℃反应10 h的条件下,获得的...     

Highly Tunable Thiol-Ene Photoresins for Volumetric Additive Manufacturing

Volumetric additive manufacturing (VAM) forms complete 3D objects in a single photocuring operation without layering defects, enabling 3D printed polymer parts with mechanical properties similar to their bulk material counterparts. This study presents the first report of VAM-printed thiol-ene resins. With well-ordered molecular networks, thiol-ene chemistry accesses polymer materials with a wide range of mechanical properties, moving VAM beyond the limitations of commonly used acrylate formulations. Since free-radical thiol-ene polymerization is not inhibited by oxygen, the nonlinear threshold response required in VAM is introduced by incorporating 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a radical scavenger. Tuning of the reaction kinetics is accomplished by balancing inhibitor and initiator content. Coupling this with quantitative measurements of the absorbed volumetric optical dose allows control of polymer conversion and gelation during printing. Importantly, this work thereby establishes the first comprehensive framework for spatial–temporal control over volumetric energy distribution, demonstrating structures 3D printed in thiol-ene resin by means of tomographic volumetric VAM. Mechanical characterization of this thiol-ene system, with varied ratios of isocyanurate and triethylene glycol monomers, reveals highly tunable mechanical response far more versatile than identical acrylate-based resins. This broadens the range of materials and properties available for VAM, taking another step toward high-performance printed polymers.     

Multifunctional Nanoengineered Hydrogels Consisting of Black Phosphorus Nanosheets Upregulate Bone Formation

Tissue‐engineered hydrogels have received extensive attention as their mechanical properties, chemical compositions, and biological signals can be dynamically modified for mimicking extracellular matrices (ECM). Herein, the synthesis of novel double network (DN) hydrogels with tunable mechanical properties using combinatorial screening methods is reported. Furthermore, nanoengineered (NE) hydrogels are constructed by addition of ultrathin 2D black phosphorus (BP) nanosheets to the DN hydrogels with multiple functions for mimicking the ECM microenvironment to induce tissue regeneration. Notably, it is found that the BP nanosheets exhibit intrinsic properties for induced CaP crystal particle formation and therefore improve the mineralization ability of NE hydrogels. Finally, in vitro and in vivo data demonstrate that the BP nanosheets, mineralized CaP crystal nanoparticles, and excellent mechanical properties provide a favorable ECM microenvironment to mediate greater osteogenic cell differentiation and bone regeneration. Consequently, the combination of bioactive chemical materials and excellent mechanical stimuli of NE hydrogels inspire novel engineering strategies for bone‐tissue regeneration.     

Layered Rare‐Earth Hydroxide/Polyacrylamide Nanocomposite Hydrogels with Highly Tunable Photoluminescence

Polymer nanocomposite (NC) hydrogels, with 3D networks composed of delaminated inorganic nanoparticles and a polymer matrix, usually display super mechanical toughness. However, the few types of inorganic materials and relatively scarce research for NC hydrogel functions seriously limit their applications. For the first time layered rare‐earth hydroxide (LRH)/polyacrylamide NC hydrogels with highly tunable photoluminescence (PL) function are reported, prepared via a convenient and green in situ polymerization process. Interestingly, the NC hydrogels reveal exciting multicolored PL phenomenon (green, yellow, orange, reddish‐orange to bluish violet), long luminescence lifetime, and relatively high quantum efficiency. Furthermore, the fascinating PL function is highly tunable by adjusting LRH constituent or its concentration, and excitation wavelength. The results highlight the fabrication and applications of functional polymer NC hydrogels with highly tunable PL function.     

pH敏感性多孔半纤维素水凝胶的制备及药物释放性能研究

以聚乙二醇(PEG)为致孔剂,利用自由基聚合法制备了具有多孔结构的半纤维素接枝共聚丙烯酰胺水凝胶,分别用FT-IR和SEM对水凝胶的结构和表面形态进行了分析;研究了水凝胶的pH值敏感性以及单体比例、PEG用量、PEG分子量和交联剂对溶胀率的影响;最后,以亚甲基蓝为模型药物研究了该水凝胶对药物的释放性能。实验结果表明,PEG为致孔剂,没有参与聚合反应;该水凝胶具有多孔结构以及优良的pH值敏感性,能够实现药物的控制释放,有望成为一种良好的药物载体。     

Click synthesis of the thermo- and pH-sensitive hydrogels containing β-cyclodextrins

Novel intelligent hydrogels containing β-cyclodextrins were prepared by tandem physical and chemical crosslinking method based on Diels–Alder reaction. First, dienophile-functionalized cyclodextrins (HCD–AMI) were synthesized by the coupling reaction of hydroxyethyl-β-cyclodextrins and N-maleoyl alanine (AMI); diene-functionalized polymers (PFMIPA) were synthesized by free radical copolymerization of N-isopropylacrylamide and furfuryl amine maleic acid monoamide, a novel monomer synthesized in our lab. Then, the LCSTs of the PFMIPA were estimated by transmittance measurements of copolymer solutions. After the as-synthesized PFMIPA and HCD–AMI were dissolved separately in water and mixed, the hydrogels with physical crosslinks formed quickly within 10 s at 37 °C. Subsequently, chemical crosslinks came into being gradually due to Diels–Alder reaction. Therefore, there are both physical crosslinks and chemical crosslinks in as-prepared hydrogels, resulting in the improvement of the mechanical strength of the hydrogels. And the in vitro degradation behaviors of the resultant hydrogels were given a pilot study. A general gravimetric method was used to study the swelling behavior of the hydrogels. It was found that the hydrogels showed good pH/temperature-sensitivity. The strategy described here has several advantages for preparing intelligent hydrogels including tunable gelation rate, mild reaction conditions, no initiator or catalyzer, and no organic solvent. We believe that this novel, potentially biocompatible hydrogels could have biomedical applications, especially in the area of tissue engineering and drug-controlled release carriers.     

Organic redox-initiated polymerization process for the fabrication of hydrogels for colon-specific drug delivery

Organic-redox initiated polymerization technique based on the co-initiators system comprising benzoyl peroxide and N-phenyldiethanolamine was used at ambient temperature to fabricate pH-responsive hydrogels. The effects of changes in the concentration of the co-initiators system, the ratio in which the co-initiators combined, the type of the polymerization solvent, the pH of the hydrating medium, the concentration of the cross-linking agent based on azo-bond and the pH-sensitive cross-linking agent on the properties of the hydrogels were investigated. Increasing the concentration of the co-initiators system, decreasing the concentration of the two types of cross-linking agents, and replacing DMSO by ethanol as the polymerization solvent resulted in hydrogels with increased equilibrium swelling ratio and increased molecular weight between cross-links at pH 7.4. Increasing the concentration of N-phenyldiethanolamine while keeping the concentration of benzoyl peroxide constant gave hydrogels with increased equilibrium swelling ratios. The equilibrium swelling ratios of the hydrogels at pH 2.0 were not affected by the factors investigated. The polymerization technique may be suitable for the design of drug delivery systems containing thermolabile bioactive agents like peptides and proteins.