基于互穿网络技术构筑的氧化海藻酸钠/纤维素纳米晶/聚丙烯酰胺-明胶双网络水凝胶与性能

为了提高海藻酸盐水凝胶的生物应用性，以氧化海藻酸钠（OSA）为原料，采用互穿网络技术、纤维素纳米晶（CNCs）补强和明胶（GT）表面覆积相结合的方法构建了OSA/CNCs/PAM-GT复合水凝胶（其中，PAM为聚丙烯酰胺）。通过FTIR、TGA、XRD、SEM、溶胀性和降解性实验以及细胞相容性测试考察了CNCs含量对OSA/CNCs/PAM-GT复合水凝胶结构和性能的影响。结果表明，CNCs能够与基体中的聚合物产生相互作用力。随着CNCs含量的增加，OSA/CNCs/PAM-GT复合水凝胶的孔隙率下降，力学性能提高，其溶胀率随CNCs含量增加呈下降趋势（下降幅度较小）而生物降解率呈上升趋势，说明CNCs能够在一定程度上调控复合水凝胶的物化性能。OSA/CNCs/PAM-GT复合水凝胶展现出较好的细胞黏附、增殖和分化性能。当CNCs的含量为0.5%时（以OSA溶液质量为基准，下同），人骨瘤(MG63)细胞增殖效果最佳，而CNCs的含量为1.5%时，MG63细胞分化效果最显著。     

3D打印纳米纤维/藻酸盐基水凝胶的制备与表征

以2,2,6,6-四甲基哌啶氧化物(TEMPO)氧化细菌纤维素(TOBC)作为增强体,制备了一系列的纳米纤维/藻酸盐(SA)基纳米复合水凝胶,研究了TOBC对纳米复合水凝胶的微观形貌、压缩、溶胀、生物相容性等性能的影响。通过流变实验与3D打印实验探究TOBC/SA纳米复合水凝胶的可印刷能力。结果表明,TOBC的加入显著增强了SA水凝胶的压缩性能。当TOBC含量为50%时,水凝胶压缩强度可达260.9 kPa,压缩性能最优。TOBC增强了混合油墨的非牛顿性,并使触变恢复能力最高达到83%,可3D打印制造出结构可控的复杂结构。纳米复合水凝胶表现出优异的细胞相容性,在生物医用领域特别是组织再生具有潜在的应用前景。     

PAM/SA/CNFs复合水凝胶的制备与性能研究

通过溶液交联聚合法制备了聚丙烯酰胺(PAM)/海藻酸钠(SA)/纤维素纳米纤维(CNFs)半互穿网络结构复合水凝胶。研究了不同添加量的CNFs对SA/PAM/CNFs复合水凝胶的溶胀性能和力学性能的影响;并测定了该复合水凝胶对亚甲基蓝染料的吸附性能。结果表明:当CNFs添加量为0.1ω/%时,复合水凝胶对亚甲基蓝染料的吸附效果最好,且平衡溶胀度最大为9.47,复合水凝胶压缩应力达到114.64 kPa。     

纳米纤维/海藻酸钙抗菌复合水凝胶的制备与表征

海藻酸钙水凝胶敷料作为一种"湿疗法"产品广泛用于伤口护理领域,但其无抗菌性,且缺乏细胞黏附的位点。通过将海藻酸盐和纳米氧化细菌纤维素(TOBC)共混,使用浸渍富集法负载抗菌剂聚六亚甲基双胍(PHMB)制备出一种多功能复合水凝胶,并使用场发射扫描电镜、酶标仪、激光共聚焦显微镜对复合水凝胶的结构和性能进行表征。结果表明:复合水凝胶为透明状,表面存在大量的纳米纤维,生物活性得到提高。使用0.001%PHMB溶液处理后,复合水凝胶对于大肠埃希菌和金黄葡萄球菌均具有良好抗菌效果,同时兼具优异的生物相容性。     

壳聚糖/明胶/聚乙烯醇复合水凝胶的溶胀性能研究

以聚乙烯醇(PVA)、明胶和壳聚糖为原料,以戊二醛为交联剂,在醋酸溶液中通过共混交联反应合成了壳聚糖/明胶/聚乙烯醇复合水凝胶,考察了聚乙烯醇/壳聚糖/明胶的质量比、交联剂用量、反应温度、反应时间对复合水凝胶溶胀性能的影响。通过正交实验,确定制备复合水凝胶的优化条件如下:交联剂用量为6 mL、反应温度为75℃、反应时间为70 min、聚乙烯醇/壳聚糖/明胶的质量比为1∶2∶2,在此优化条件下合成的壳聚糖/明胶/聚乙烯醇复合水凝胶溶胀性能良好,对水的平衡溶胀度达到985%。     

蔗渣纤维素/羧甲基纤维素钠复合水凝胶的制备与性能研究

利用LiOH/尿素低温溶剂溶解蔗渣纤维素,以环氧氯丙烷为化学交联剂,通过调控蔗渣纤维素与羧甲基纤维素钠(CMC)的质量比例,制备蔗渣纤维素/CMC高吸水复合水凝胶。通过FT-IR、TG和SEM等仪器对水凝胶进行结构表征和性能分析,并研究水凝胶的溶胀性能及其影响因素。结果表明,蔗渣纤维素/CMC复合水凝胶在纯水中具有很高的溶胀率,均超过1000g/g,其在纯水中的再溶胀率,最高可达182 g/g,且再溶胀行为符合二级速率方程。     

化学交联法制备ZnO/PVA复合水凝胶

以氯化锌为原料制备纳米氧化锌(ZnO),采用化学交联法法制备ZnO/聚乙烯醇(PVA)复合水凝胶,研究ZnO加入量对复合水凝胶拉伸强度、断裂伸长率以及溶胀性能的影响。实验结果表明:ZnO含量为0.1%时,复合水凝胶的拉伸强度和断裂伸长率最大,而ZnO含量为0.4%时,复合水凝胶的溶胀率最大。     

可注射甘油磷酸钠-壳聚糖/海藻酸钠复合水凝胶的制备及性能研究

通过物理交联方法,将海藻酸钠(SA)与甘油磷酸钠-壳聚糖(GP-CS)复合制备可注射GP-CS/SA复合水凝胶,考察了物料比(GP-CS与SA的质量比)对复合水凝胶凝胶化时间、溶胶含量、微观形态、热稳定性、平衡溶胀等物理化学性能的影响。结果表明,复合水凝胶中SA比例越大,凝胶化时间越短,溶胶含量越少;扫描电镜和红外光谱分析表明,GP-CS与SA通过物理交联形成三维网络结构的水凝胶;热重分析表明,复合水凝胶与GP-CS水凝胶的热稳定性没有很显著差异;平衡溶胀实验表明,随着SA比例的增大,复合水凝胶的溶胀率和平衡溶胀率升高。GP-CS/SA复合水凝胶比单一的GP-CS水凝胶具有更高的机械强度、更好的吸水性和平衡溶胀性能。     

纳米铜碳/海藻酸钠复合水凝胶的制备及性能

以吸附了硫酸铜的天然棉纤维为原料,高温热解制备纳米铜碳复合材料(NCCC),并利用原位释放法以二价钙离子为交联剂制备出纳米铜碳复合材料/海藻酸钠(NCCC/SA)复合水凝胶,来缓释抑藻材料NCCC。调节CaCO₃/SA的质量比,考察海藻酸钠水凝胶的力学性能、溶胀和降解性能来优选凝胶载体。调节NCCC/SA质量比,考察NCCC/SA复合水凝胶力学性能、溶胀和降解性能。NCCC/SA质量比越大,复合水凝胶的力学性能越差,但其溶胀和降解性能几乎没有影响。为了应对动态水环境的使用要求,最终选用CaCO₃/SA的质量比为18.18%的海藻酸钠水凝胶为载体,NCCC/SA质量比为2∶1来制备复合水凝胶,并模拟NCCC的缓释,为NCCC应用于抑藻的研究奠定了理论基础。     

壳聚糖纤维/壳聚糖/海藻酸钠水凝胶溶胀性能与抑菌性能

制备了壳聚糖(CS)/海藻酸钠(SA)复合水凝胶,并通过加入吸水性壳聚糖长纤维、45%壳聚糖水刺无纺布、80%壳聚糖水刺无纺布、100%壳聚糖水刺无纺布、100%壳聚糖针刺无纺布这五种纤维,增强复合水凝胶的力学性能,探究了复合水凝胶的吸水溶胀性能与抑菌性能。结果表明,加入纤维后水凝胶在蒸馏水中的溶胀比明显降低,在碱性环境中,水凝胶的溶胀比显著上升,在偏中性环境中,水凝胶的溶胀比最低;加入纤维后,复合水凝胶仍具有一定的抑菌性,无纤维添加的水凝胶呈现出的抑菌能力一般,而加入了吸水性壳聚糖长纤维的具有最佳的抑菌性能。     

Fabrication of alginate/sericin/cellulose nanocrystals interpenetrating network composite hydrogels with enhanced physicochemical properties and biological activity

Sodium alginate (SA) possesses good biocompatibility and can form hydrogel materials under certain conditions, which has been widely used in tissue engineering. However, the absence of cellular recognition sites and low mechanical strength for single-component alginate (ALG) hydrogels limit their practical applications. Therefore, enhancing the shortcomings of ALG hydrogels and augmenting their characteristics hold immense importance for their medical uses. In this study, comprehensively considering the excellent properties of cellulose nanocrystals (CNCs) and sericin (SS), the alginate/sericin/cellulose nanocrystalline (ALG/SS/CNCS) composite hydrogels were constructed by interpenetrating network (IPN) technique using hydroxyapatite/D-glucono-δ-lactone (HAP/GDL) as the endogenous ionic cross-linking agent of SA, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) as the chemical covalent cross-linking agent of SS and CNCS as the reinforcing agent. The effects of SS and CNCs additions on the comprehensive properties of ALG/SS/CNCs composite hydrogels, such as their morphologies, structure, mechanical properties, swelling, degradability, and cytocompatibility were investigated. The findings indicated that the ALG/SS/CNCS IPN composite hydrogels which were created through the physical blending of SA and SS, displayed a consistent three-dimensional form and a porous configuration. The weak mechanical strength of pure ALG hydrogels can be effectively improved and the swelling stability and mechanical properties of the composite hydrogels can be enhanced through the construction of IPN network and the incorporation of CNCs, thanks to the presence of intermolecular hydrogen bonding. The biodegradability of ALG/SS/CNCS composite hydrogels increased as the SS content increased, indicating that SS facilitated their biomineralization due to its inherent susceptibility to degradation. The results of the cell compatibility test conducted in a laboratory setting showed that SS and CNCS had the ability to enhance the attachment, proliferation, and differentiation of MC3T3-E1 cells on the ALG/SS/CNCS composite hydrogels. Hence, incorporating SS and CNCS into the alginate matrix to create IPN composite hydrogels could significantly enhance the physicochemical and biological characteristics of ALG hydrogels, thus rendering them appropriate for tissue engineering purposes.     

pH/temperature‐responsive semi‐IPN hydrogels composed of alginate and poly(N‐isopropylacrylamide)

Amino semitelechelic poly(N‐isopropylacrylamide) (PNIPAAm) was prepared by radical polymerization with aminoethanethiol hydrochloride as a chain‐transfer agent. Semi‐interpenetrating polymer network (semi‐IPN) hydrogels, composed of alginate and amine‐terminated PNIPAAm, were prepared by crosslinking with calcium chloride. From the swelling behaviors of semi‐IPNs at various pH's and Fourier transform infrared spectra at high temperatures, the formation of a polyelectrolyte complex was confirmed from the reaction between carboxyl groups in alginate and amino groups in modified PNIPAAm. Semi‐IPN hydrogels reached an equilibrium swelling state within 24 h. The water state in hydrogels, investigated by differential scanning calorimetry, showed that sample CAN55 [alginate/PNIPAAm (w/w) = 50/50] exhibited the lowest equilibrium water content and free water content among the hydrogels tested, which was attributed to its more compact structure compared to other samples and the high content of interchain bonding within the hydrogels. Alginate/PNIPAAm semi‐IPN hydrogels exhibited a reasonable sensitivity to the temperature, pH, and ionic strength of swelling medium. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1128–1139, 2002     

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

This work refers to the synthesis and characterization of thermosensitive hydrogels based on interpenetrating polymer networks (IPNs) of poly(N‐isopropylacrylamide) (PNIPAAm) and calcium alginate in the form of films. The influence of the crosslinking degree of PNIPAAm and alginate content on thermal, swelling, mechanical, and morphological properties of hydrogels is investigated in detail. Characterization of pure PNIPAAm hydrogels and IPN hydrogels was performed by FTIR, DSC, DMA, and SEM. In addition, the studies of equilibrium swelling behavior as well as swelling, deswelling, and reswelling kinetics are performed. The results obtained imply the benefits of synthesizing IPNs based on PNIPAAm and calcium alginate over pure PNIPAAm hydrogels. The presence of calcium alginate contributes to the improvement of mechanical properties, the deswelling rate of hydrogels, and the network porosity, without altering the thermosensitivity of PNIPAAm significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of alginate/poly(N‐isopropylacrylamide) semi‐interpenetrating and fully interpenetrating polymer network hydrogels with γ‐ray irradiation and their swelling behaviors

Semi‐interpenetrating polymer network (semi‐IPN) and fully interpenetrating polymer network (full‐IPN) hydrogels composed of alginate and poly(N‐isopropylacrylamide) were prepared with γ‐ray irradiation. The semi‐IPN hydrogels were prepared through the irradiation of a mixed solution composed of alginate and N‐isopropylacrylamide (NIPAAm) monomer to simultaneously achieve the polymerization and self‐crosslinking of NIPAAm. The full‐IPN hydrogels were formed through the immersion of the semi‐IPN film in a calcium‐ion solution. The results for the swelling and deswelling behaviors showed that the swelling ratio of semi‐IPN hydrogels was higher than that of full‐IPN hydrogels. A semi‐IPN hydrogel containing more alginate exhibited relatively rapid swelling and deswelling rates, whereas a full‐IPN hydrogel showed an adverse tendency. All the hydrogels with NIPAAm exhibited a change in the swelling ratio around 30–40°C, and full‐IPN hydrogels showed more sensitive and reversible behavior than semi‐IPN hydrogels under a stepwise stimulus. In addition, the swelling ratio of the hydrogels continuously increased with the pH values, and the swelling processes were proven to be repeatable with pH changes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4439–4446, 2006     

Injectable self-healing nanocellulose hydrogels crosslinked by aluminum: Cellulose nanocrystals vs. cellulose nanofibrils

With excellent biocompatibility and unique physiochemical properties, nanocelluloses including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are promising candidates for preparing biomedical hydrogels. CNCs and CNFs are different in morphology and surface charges. Herein, CNCs and two CNFs (CNFs-C, Carboxylated CNFs; CNFs-P, Phosphorylated CNFs) were synthesized and applied to fabricate hydrogels through metal crosslinking. Aluminum crosslinking was found to be the best choice for enhancing the strength. This study systematically compared the morphologies, storage modulus, loss factor, continuous shear ramp, self-healing, swelling, in vitro degradation and injectable properties of the fabricated hydrogels. Further, a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications. At the same nanocellulose concentration and after Al³⁺ crosslinking, CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels. While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs. These results provide detailed insights into nanocellulose hydrogels, making it possible to use these guidelines to select hydrogels for desired performance.     

Synthesis and characteristics of interpenetrating polymer network hydrogels composed of alginate and poly(diallydimethylammonium chloride)

Temperature‐ and pH‐responsive interpenetrating polymer network (IPN) hydrogels, with sodium alginate (SA) and poly(diallydimethylammonium chloride) (PDADMAC), constructed by a sequential IPN method, were studied. The characterizations of the IPN hydrogels were investigated by FTIR, DSC, and swelling tests under various conditions. The prepared IPN hydrogels exhibited relatively high swelling ratios, in the range of 380–690%, at 25°C. The swelling ratios of SA/PDADMAC IPN hydrogels were pH and temperature dependent. DSC was used for the quantitative determination of the freezing and nonfreezing water contents of the hydrogels. The amount of free water increased with the increasing PDADMAC content of the IPN hydrogels. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3705–3709, 2004     

Water-swellable,tough, and stretchable inorganic–organic sulfoaluminate cement/polyacrylamide double-network hydrogel composites

Effectively improving the mechanical properties of the hydrogel can greatly broaden its application range. The design concept of forming a double-network structure by organic–inorganic hybridization can greatly enhance the mechanical properties of traditional hydrogels. Here, a series of organic–inorganic double-network (OIDN) polyacrylamide/(sulfoaluminate cement) (PAM/SAC) composite gels by solution polymerization were synthesized at room temperature. The OIDN composite gels not only retain the characteristics of water swelling but also exhibit excellent tensile properties (stress and strain are 12 MPa and 2500%, respectively) and compressive strength (stress and strain are 65 MPa and 80%, respectively). In the preparation process, a brittle inorganic network of hydrated sulfoaluminate (hydra-SAC) and a ductile network of polyacrylamide (PAM) were formed by the manner of interpenetrating. The phase composition and thermal stability of the OIDN composite gels were characterized and determined by FTIR, XRD, SEM, and TGA, respectively. The effect of SAC on swelling and mechanical performance of the OIDN composite gels was also investigated. The results show that the use of SAC hybrid hydrogels can effectively improve the mechanical strength, and the OIDN composite gels are expected to be a potential grouting and plugging functional material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47905.     

Electrospun cellulose nanofiber reinforced soybean protein isolate composite film

This article presents the fabrication of cellulose nanofibrous mats (CNM) reinforced soybean protein isolate (SPI) composite with high visible light transmittance. The CNM was composed of cellulose nanofibers generated from electrospinning technique. The microstructure of the fractured surface of composite films was characterized by scanning electron microscopy (SEM). The light transmittance, mechanical properties, and swelling ratio of CNM/SPI composite were investigated in terms of CNM content in the composite. Because of the ultrafine diameter and superhigh length‐to‐diameter ratio of nanofibers, large amount of cellulose nanofibers fibers distribute in the SPI matrix to form an interpenetrating network (IPN) like composite material. It was found that strong interfacial interactions occurred at the cellulose nanofiber/SPI interfaces. The incorporation of 20 wt % cellulose nanofibers in the SPI matrix resulted in great improvement of mechanical strength and Young's modulus by respectively 13 and 6 times more than neat SPI film. More interestingly, this composite was translucent with light transmittance of over 75% at 700 nm. Furthermore, the swelling ratio of this IPN‐like CNM/SPI composite decreased from 106 to 22% as CNM content increased from 0 to 20 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and properties of temperature‐sensitive soy protein/poly(N‐isopropylacrylamide) interpenetrating polymer network hydrogels

Temperature‐sensitive interpenetrating polymer network (IPN) hydrogels based on soy protein and poly(N‐isopropylacrylamide) were successfully prepared. The structure and properties were systematically characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis, and the swelling and deswelling behavior was also investigated. It was found that the hydrogels had good miscibility, thermal stability and temperature sensitivity, and the lower critical solution temperature was ca 32 °C. Changing the content of soy protein or crosslinker could be used to control the swelling behavior, water retention and network structure of the IPN hydrogels. The results show that the novel IPN hydrogels may be of potential interest in drug delivery systems. Copyright © 2011 Society of Chemical Industry     

The electrospun polyhydroxybutyrate fibers reinforced with cellulose nanocrystals: Morphology and properties

Polyhydroxybutyrate (PHB) has been used in the biomedical field. However, the poor mechanical properties of PHB have limited its application. Here, electrospun fibrous nanocomposite mats reinforced with cellulose nanocrystals (CNCs) were fabricated by using PHB as polymeric matrix. The morphological, thermal, mechanical properties, as well as cytotoxicity were characterized. Increasing the concentration of CNCs caused a decrease in diameter of the electrospun fibers. Moreover, thermal analysis indicated that melting temperature of PHB/CNCs electrospun fibers were improved with the increased CNCs content. The addition of CNCs gradually enhanced the tensile strength till 8 wt % content followed by a gradual decrease at higher CNCs content (12–22 wt %) in tensile strength. The PHB/CNCs electrospun fibers were nontoxic to L‐929 and capable of supporting cell proliferation in all conditions. This study demonstrates that fibrous PHB/CNCs electrospun fibers are cytocompatible and potentially useful mechanical properties for biomedical application. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43273.