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。     

双硒葡聚糖水凝胶的合成及其药物释放行为

首先,通过双硒化钠(Na2Se2)与11-溴-1-十一醇的亲核取代反应合成了一种二羟基二硒化物;然后,通过该二硒化物与异佛尔酮二异氰酸酯(IPDI)反应合成了一种异氰酸根封端的双硒交联剂;最后,通过葡聚糖与该交联剂的反应合成了一种含双硒键的葡聚糖水凝胶。采用核磁共振氢谱(~1H-NMR)、傅里叶红外光谱(FT-IR)、凝胶渗透色谱(GPC)、拉曼光谱(Raman)、旋转流变仪(Rheology)、紫外-可见分光光度计(UV-Vis)等表征方法研究了产物的结构、溶胀性能、氧化响应行为、流变性能和体外药物释放行为。结果表明:含双硒键的葡聚糖水凝胶具有氧化响应能力;在没有氧化刺激条件下,该水凝胶24h的累积药物释放量为45%左右,而在氧化刺激条件下(w(H_2O_2)=0.2),只需14h便可释放90%的负载药物。     

形状记忆水凝胶研究进展

形状记忆水凝胶(SMHs)是一种功能高分子材料,兼具形状记忆效应、高含水量以及良好的生物相容性等优点,其较高强度的三维多孔结构为细胞粘附、生长和迁移提供了良好的类组织微环境,尤其是在外界刺激下的形状记忆能力使其在人工智能和医疗领域显示出诱人的应用前景.本文总结了SMHs的合成方法与形状记忆原理,并阐述了其在3D打印、传...     

聚乙烯醇/聚乙烯吡咯烷酮/碘复合水凝胶的制备与性能

采用低温冷冻的方法,通过改变聚乙烯醇(PVA)和聚乙烯吡咯烷酮碘络合物(PVP-I)的配比、冷冻时间、冷冻-解冻循环次数,制备出一种可调控力学性能的PVA/PVP-I复合水凝胶.研究了该复合水凝胶的机械性能、微观结构、碘缓释性能和抑菌性质.研究结果表明, PVA/PVP-I复合水凝胶可调控的力学性质可以满足伤口敷料对水凝胶力学性质的需求;复合水凝胶的网络结构可以有效降低碘在紫外线下的分解速度,实现对碘的稳定保护作用及控制释放,从而发挥水凝胶持续抑菌性能,为抑菌水凝胶的设计制备提供了新思路.     

非共价键交联海藻酸钠水凝胶的制备与性能

天然多糖海藻酸钠制备的水凝胶具有优越的生物相容性和生物组织相似性,作为生物医用材料在药物控制释放、组织工程支架、抗菌材料及创伤敷料等领域发挥着越来越大的作用。本文在介绍海藻酸钠物化性质的基础上,重点综述了非共价键交联(静电作用、氢键、范德华力、亲疏水作用等)海藻酸钠水凝胶的制备方法以及性能表征方法,最后讨论了制备方法及性能表征研究中的一些需要解决的问题。     

PEGDA/NIPAM共聚物水凝胶的药物释放性能研究

以IRGACURE2959为光引发剂,聚乙二醇双丙烯酸酯(PEGAD)和N-异丙基丙烯酰胺(NIPAM)为单体,通过紫外光引发光聚合,合成了PEGDA/NIPAM共聚物水凝胶,研究了凝胶于不同酸度介质及不同温度中对阿司匹林的释放行为。结果表明,模拟胃肠液中,随释放时间的延长,载药凝胶对药物的累积释放率增加。NIPAM单体的引入增大药物累积释放率,药物缓释时间延长,具有良好的药物释放性能。凝胶对药物的缓释受温度与释放时间的影响,在37℃和45℃时,随释放时间增加,药物累积释放率增大;在30℃时,随释放时间的增长,累积释放率先增大后减小。     

CO2致孔的海藻酸钠水凝胶对BSA的可控释放

本文以碳酸氢钠(NaHCO3)为致孔剂制备了海藻酸钠/聚丙烯酸复合水凝胶(G-APCGs),采用扫描电子显微镜(SEM)观察了其形貌.水凝胶(G-APCGs)有清晰的孔洞结构,其结构受到单体和致孔剂投加量影响.进一步研究了丙烯酸(AA)、NaHCO3投加量对复合水凝胶溶胀性能的影响.结果表明,复合水凝胶具有良好的pH敏...     

PVP-semi-IPN-PCL/PLA水凝胶制备及负载卡马西平药物共晶体外释放

通过N-乙烯基吡咯烷酮(N-vinyl pyrrolidone, NVP)在聚己内酯(polycaprolactone, PCL)、聚乳酸(poly(lactic acid),PLA)乙酸乙酯溶液中自由基聚合,制得聚乙烯吡咯烷酮(Polyvinylpyrrolidone, PVP)/聚己内酯、聚乳酸半互穿网络(semi-interpenetrating network, semi-IPN)水凝胶(PVP-semi-IPN-PCL/PLA)。实验制得疏水/亲水比例分别为1∶9、3∶7、5∶5的三种水凝胶。采用溶剂挥发法制备卡马西平-丁二酸药物共晶(carbamazepine-succinic acid, CBZ-SUC)。使用PVP-semi-IPN-PCL/PLA负载CBZ-SUC共晶,考察上述三种凝胶药物载体的载药能力及体外释放行为。使用1∶9、3∶7、5∶5比例凝胶制备了载药量分别为17%、19%、21%,包封率分别为71%、83%、89%的载药凝胶,其在37℃,pH=6.8 PBS溶液中体外释放效果均优于未使用凝胶载体的CBZ-SUC共晶。其中,3∶7组载药凝胶的累积释放量最高,...     

疏水改性凝胶的合成及其药物释放性能的研究

以偶氮二异丁腈为引发剂,通过化学引发聚合合成甲基丙烯酸β-羟乙酯(HEMA)/N-乙烯基吡咯烷酮(NVP)二元共聚物和HEMA/NVP/甲基丙烯酸乙酯(或甲基丙烯酸丁酯)三元共聚物水凝胶,研究了凝胶在不同的酸度介质中对小分子药物阿司匹林的释放过程,结果表明,在模拟胃肠道条件下,随着疏水性单体的加入使凝胶的药物释放速率减缓,可实现药物的控制缓释作用。     

大茴香醛改性海藻酸钠凝胶的制备及释药性能

在酸催化下使海藻酸钠与对甲氧基苯甲醛(又名大茴香醛)发生缩醛化反应,使其疏水改性,并将其制备成凝胶。利用红外(FTIR)、荧光、透射电镜(TEM)、扫描电镜(SEM)、紫外、热重分析(TGA)对产物进行了表征。结果表明,大茴香醛成功地与海藻酸钠发生了反应。该凝胶可以作为药物载体对牛血清白蛋白进行包埋释放,结果发现,改性后的产物其载药率和缓释性能比未改性的海藻酸钠有了一定的提高。     

Preparation and characterization of ternary composite films of polyvinyl alcohol/sodium alginate/TiO<Subscript>2</Subscript>

Nano-TiO₂ with anionic surface active agent sodium dodecylsulfate (SDS) modified, the poly(vinyl alcohol)/sodium alginate/TiO₂ composite films were prepared by method of solution blending representing. The structure of the films was analyzed by XRD and SEM. In addition, air permeability rate, swelling ratio, light transmittance, mechanical properties, and antibacterial properties were tested. The results showed that in compound membrane there was a strong force between poly(vinyl alcohol)/sodium alginate and TiO₂ particles, indicating that there was good compatibility between the sodium alginate and the poly(vinyl alcohol). The mixed membranes were of good water resistance, tensile strength, and closure. When the titanium dioxide content increased appropriately, they had very good mechanical properties. In addition, the antibacterial properties of composite membrane gradually increased with the increase in the TiO₂content.     

The controlled release behavior and pH‐ and thermo‐sensitivity of alginate/poly(vinyl alcohol) blended hydrogels

Poly(vinyl alcohol) (PVA) was blended with sodium alginate (Alg) in various ratios and crosslinked with calcium chloride and made into hydrogel membranes. The dependence of the swelling behavior of these Alg‐Ca/PVA hydrogels on pH was investigated. The temperature‐dependent swelling behavior of the semi‐interpenetrating network (semi‐IPN) hydrogels was examined at temperatures from 2 to 45°C and the enthalpy of mixing (ΔH_mix) was determined at various temperatures. The molecular structure of the hydrogels was studied by infrared spectroscopy and their water structure in the semi‐IPN hydrogels was measured by differential scanning calorimetry (DSC). The influence of Ca²⁺ content on the network structure of Alg‐Ca/PVA hydrogels was investigated in terms of the compressive elastic modulus, effective crosslinking density, and the polymer–solvent interaction parameter based on the Flory theory. The loading of alizarin red S (ARS) followed the Langmuir isotherm mechanism and the release kinetics of ARS from the Alg‐Ca/PVA hydrogels followed the Fickian diffusion mechanism. Copyright © 2008 John Wiley & Sons, Ltd.     

Electrically induced gel-sol transition of polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels

Polyvinyl alcohol/polyacrylamide semi-interpenetrated hydrogels were prepared via freeze-thaw process. When a 20 V of DC was applied across the gels, the gels with lower polyacrylamide content underwent a contraction or partly turned into solution, while for the gels with higher polyacrylamide concentration, a complete gel-sol transition was observed in a short time.     

PVA/Gel水凝胶的电刺激可逆弯曲偏转行为研究

制备不同比例的聚乙烯醇/明胶水凝胶,在直流电场作用下,测试聚乙烯醇/明胶水凝胶在不同温度和不同浓度Na2CO3溶液中的电刺激弯曲偏转行为,绘制聚乙烯醇/明胶水凝胶弯曲偏转角随时间的变化曲线,考察了可逆弯曲偏转变化的周期性。     

多孔纳米羟基磷灰石/聚乙烯醇复合水凝胶的表征

本文通过采用溶盐致孔法,制备了多孔纳米羟基磷灰石／聚乙烯醇复合水凝胶材料。用透射电子显微镜、红外光谱、扫描电子显微镜和图像分析对材料进行了表征。结果表明纳米羟基磷灰石与聚乙烯醇之间有一定键合,并且多孔纳米羟基磷灰石／聚乙烯醇复合水凝胶中大孔呈均匀分布且相互贯通,复合水凝胶的含水率在80％左右。该种多孔复合水凝胶是可用于人工角膜支架,是一种很有开发前景的生物医用材料。     

十聚钨酸/聚乙烯醇导电膜的制备

最近发现粉状白钨酸在聚乙烯醇(PVA)或其它高分子水溶液中有相当大的溶解度,可以得到稳定的十聚钨酸溶液,并进而得到含十聚钨酸的高分子薄膜。通过光谱鉴定和组成分析,证明了在聚乙烯醇存在下,十聚钨酸能以固态形式存在,而且这是首例十聚钨酸/高分子复合物,并且还研究了组成、湿度、光致变色对复合物薄膜导电性的影响。     

Preparation and characterization of aqueous stable electro-spun nanofibers using polyvinyl alcohol/polyvinyl pyrrolidone/zeolite

Cross-linked polyvinyl alcohol/polyvinyl pyrrolidone/zeolite fibers were prepared in the presence of potassium peroxodisulphate (K₂S₂O₈) under the curing process by the electrospinning technique. The narrowest nanofibers of PVA/PVP (50:50) were prepared under optimum experimental conditions of 2.5 × 10^?4 mol of K₂S₂O₈, an applied voltage of 22 KV, the distance of 15 cm and the feed rate of 0.2 mL/h. The progress of the cross-linking was examined by immersion of the prepared nanofibers in water and following the swelling degrees. By raising the K₂S₂O₈ amount and curing time, the cross-linking density was increased. X-ray diffraction (XRD) demonstrated that the crystallinity of the nanofibers was decreased by the increase of K₂S₂O₈ and the lowest crystallinity was observed for PVA/PVP (70:30). The contact angle of nanofibers was decreased from 72° to 34 by increasing PVP ratio from 30 to 70. The morphology of the nanofibers before and after immersion in the simulated body fluid (SBF) was studied using electron scanning microscopy (SEM) and PVA/PVP (70:30) showed the highest changes in the morphology while the lowest one was observed for PVA/PVP (50:50). Moreover, the cross-linked PVA/ PVP with the ratio of 50:50 had the narrowest diameter of 200 ± 100 nm, and by addition of about 0.5% zeolite, it was even reduced more to 150 ± 50 nm. The cross-linked nanofibers (50:50) with 0.5 wt% and 1.5 wt% zeolite nanoparticles showed the tensile modules of 416.26 and 703.52 MPa, respectively, while in the absence of zeolite, it was209.25 MPa. Fibroblast L929 cells were cultured on the cross-linked PVA/PVP/zeolite (50:50:0.5) nanofiber, and the cell proliferation and growth was evaluated by MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Fibroblasts grew on the surface of scaffold showed good morphology and proliferation after seven days and the absorption amount was increased from 0.075 to 0.78     

Fabrication of polyvinyl alcohol/chitosan oligosaccharide hydrogel: physicochemical characterizations and in vitro drug release study

Abstract

Hydrogel composites from polyvinyl alcohol and chitosan have been developed by various researchers as a function of their composition for various medical applications. Although, the solubility of chitosan in acidic solvents may limit its wide bioengineering applications. In this article, we demonstrate that polyvinyl alcohol-chitosan oligosaccharide (water soluble) to develop cross-linked hydrogel network using chemical cross linker. X ray diffraction, Fourier transform infrared spectroscopy, and wettability study of these hydrogels were also performed. Lomefloxacin drug was loaded into the hydrogels and its release profile was studied.     

Viscoelastic properties of cross-linked polyvinyl alcohol and surface-oxidized cellulose whisker hydrogels

Reinforcement of polyvinyl alcohol (PVA) hydrogels was achieved by direct chemical cross-linking of surface modified microcrystalline cellulose (MCC) whiskers with PVA. In order to produce hydrogels, the MCC whiskers were first obtained by TEMPO-mediated oxidation of the cellulose substrate and ultrasonication followed by direct cross-linking to PVA (Mw 98,000) via forming acetal bonds and freeze–thawing. The viscoelastic properties of the produced hydrogels were clearly improved following the chemical cross-linking, featuring values for viscous and elastic moduli G′ and G″ on the order of 10 kPa, which is particularly interesting for biomedical orthopedic applications.     

Preparation and drug release behavior of temperature-responsive mesoporous carbons

A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery.