海藻酸锌纤维

海藻酸锌纤维是一种具有优良生物活性的功能性纤维材料,可以通过湿法纺丝直接制备,也可以通过对海藻酸钙纤维进行离子交换间接制备。在间接法制备海藻酸锌纤维的过程中,可以通过控制海藻酸钙纤维与锌盐的质量比例得到含不同浓度锌离子的纤维。由于纤维中含有对伤口的愈合有促进作用的锌离子,海藻酸锌纤维通过持续释放锌离子在医用敷料的生产中有特殊的应用价值。试验结果表明:海藻酸锌纤维在释放锌离子的过程中可以起到抑制细菌增长的作用,在医疗卫生领域具有特殊的应用价值。     

海藻酸微胶囊的制备及在药物控释中的研究进展

海藻酸具有相对温和的凝胶条件与良好的生物相容性 ,已广泛应用于药物缓释与生物医学工程。综述了海藻酸微胶囊的制作方法、增加海藻酸微囊的稳定性与控制物质扩散的主要方法及海藻酸凝胶在药物控释研究中的进展     

海藻酸钠与钙或锌离子吸附平衡过程研究

使用原子吸收分光光度法测定了海藻酸钠对锌、钙离子的吸附平衡过程。试验结果表明,海藻酸钠对钙离子的结合能力较强,对锌离子的吸附容量较高。吸附平衡热力学数据表明海藻酸钙体系较为稳定;混合离子吸附的试验结果表明对钙、锌离子的选择性系数为1.35;钙锌离子交换试验表明钙离子与锌离子在海藻酸古洛糖醛酸片段的离子交换会影响锌离子与甘露糖醛酸片段的结合。     

双乳化-凝胶法制备单分散海藻酸钙微球及其载BSA研究

采用双乳化-凝胶法制备了单分散的海藻酸钙凝胶微球,并通过正交试验系统考察了海藻酸钠浓度、氯化钙浓度、表面活性剂浓度、搅拌速度和油水比对海藻酸钙凝胶微球粒径及形貌的影响。在优化的条件下,制备出了平均粒径为4μm、单分散和球形度好的海藻酸钙凝胶微球。包埋模型药物牛血清白蛋白(BSA)的过程中,以去离子水作为洗涤液洗涤海藻酸钙微球时,BSA的包封率仅为13%左右;当水洗液的pH值为3.2时,BSA的包封率提高到66%左右,载药率可达16%,这是海藻酸钙pH值响应溶胀和BSA与海藻酸盐之间静电作用的结果。微球中BSA的体外释放曲线表明,该系统具有在模拟胃液中释药速率慢、释药量低、模拟肠液中释药迅速的特性。因此,双乳化-凝胶法制备海藻酸钙微球有望成为制备蛋白类药物控释制剂的一种新方法,以达到靶向快速给药的目的。     

高岭土的球磨疏水改性及其在海藻酸盐凝胶微球中的应用

为了提高高岭土(KL)对疏水性有机农药的亲和力,以聚甲基氢硅氧烷(PMHS)作为疏水改性剂,采用球磨法改性KL。进而,采用负压冷冻干燥技术将甲氨基阿维菌素苯甲酸盐(EB)负载到改性高岭土颗粒上,然后包覆于海藻酸盐基质中制得载药改性高岭土/海藻酸钙复合凝胶微球(MKL-CA-CMBs)。通过Zeta电位及激光粒度仪、FTIR、SEM、XRD、比表面积及孔径分析仪对改性后KL的结构、形貌和性能进行了表征,同时对MKL-CACMBs的载药和释药性能也进行了考察。结果表明,在球磨机械力作用下,PMHS以物理吸附或化学吸附的方式吸附于KL颗粒表面。改性后的KL粒径减小、比表面积增大,疏水性增强,利于疏水有机农药的负载,使高岭土/海藻酸钙复合凝胶微球(KL-CA-CMBs)的载药率(DLR)和包封率(EE)分别由6.5%和53.1%增长至9.7%和72.5%。MKL-CA-CMBs所具有的缓释性能主要基于MKL对疏水有机农药的亲和能力,剂型的释放模型属于Non-fickian扩散模型。     

超薄壁结构海藻酸钙胶囊膜制备及其功能化研究新进展

海藻酸钙胶囊膜由于具有制备过程温和环保、材料生物相容性优良等优点,广泛应用于生物医药等领域。薄壁结构的胶囊膜可减小跨膜传质阻力,加速囊膜内外物质的交换,因而备受学术界和工业界的广泛关注。近年来,具有超薄壁结构的海藻酸钙胶囊膜的制备与改性成为一个研究热点。本文综述了超薄壁结构海藻酸钙胶囊膜的制备方法及其功能化的研究新进展,重点介绍了利用共挤出毛细管装置制备超薄壁结构的海藻酸钙胶囊膜、利用精蛋白吸附与仿生硅化技术对超薄壁结构海藻酸钙胶囊膜的有机/无机杂化处理,以及利用复合纳米响应性凝胶颗粒的方法和接枝响应性聚合物高分子的方法实现超薄壁结构海藻酸钙胶囊膜的功能化改性等方面的研究现状。     

海藻酸镁凝胶的制备及其性能研究

在0.05～5 mol/L镁离子浓度范围内制备了一系列具有不同性能的海藻酸镁凝胶，考察了镁离子浓度、镁离子用量、镁盐种类和海藻酸钠M/G比值等因素对海藻酸镁凝胶成胶过程的影响，并测试了不同制备条件下凝胶的力学性能和溶胀性能。结果表明，高离子浓度可将海藻酸镁凝胶的拉伸强度提高到400 kPa以上；采用氯化镁、溴化镁、乙酸镁制备的凝胶力学性能较好。同时海藻酸镁具有成胶慢的特点，不同的制备条件可使凝胶形成时间在1 min～10 h内发生变化，显示了其在可注射水凝胶方面具有良好的应用前景。     

块状木质素磺酸钠/海藻酸钙复合气凝胶的制备、表征及性能

以木质素磺酸钠和海藻酸钠为原料,采用溶液共混法和真空冷冻干燥制备块状木质素磺酸钠/海藻酸钙复合气凝胶,通过扫描电子显微镜(SEM)、傅立叶变换红外光谱仪(FTIR)、X-射线衍射仪(XRD)、热重分析仪(TG)对其结构进行表征,并分析了其力学性能和吸附性能。结果表明,所制备的气凝胶表面呈层状包裹结构,存在尺寸不一的孔洞;木质素磺酸钠和海藻酸钠主要通过氢键和范德华力结合在一起;木质素磺酸钠的引入提高了海藻酸钙气凝胶的结晶度和热稳定性;气凝胶的压缩强度随木质素磺酸钠含量的增加逐渐减弱;气凝胶对亚甲基蓝和Pb~(2+)均表现出较强的吸附性能,其中气凝胶SA-75对亚甲基蓝的吸附率达到83.65%,气凝胶SA-50对Pb~(2+)的吸附率达到79.89%。     

国外海藻纤维的研制发展情况

<正>英国化学家ECC Stanford早在1881年首先介绍了从褐藻类海藻植物——狭叶海带(LaminariaStenophylla)中提取出的一种凝胶状物质,他把用稀碱溶液提取出的物质命名为Algin,加酸后生成的凝胶为Alginic acid,即海藻酸。1944年,英国人Speakman和Chamberlain发表了他们对海藻酸纤维的研究成果。Speakman和Chamberlain研究了从6组具有不同相对分子质量的海藻酸中加工出的纤维的性能。结果表明,海藻酸的相对分子质量对纤维的强度有一定的影响,但其影响程度不     

基于“蛋盒”结构高电化学性能活性炭的制备

与陆生植物不同,海藻中通常含有大量的海藻酸和海藻酸盐,其中海藻酸盐主要以海藻酸钙、海藻酸镁等形式存在于细胞壁中。本文利用海带中海藻酸钙的“蛋盒”式结构,对海带炭化产物进行盐酸酸洗处理,除去海藻酸钙中的钙离子,形成“蛋盒”式初始孔结构,然后采用KOH活化法制备海带基活性炭,研究海带基活性炭的孔结构特性以及电化学性能。实验结果表明：基于“蛋盒”结构制备的海带基活性炭拥有丰富的孔隙结构,其比表面积高达3027m²/g,其中73.3%由中孔比表面积提供,且中孔孔径分布比较集中,几乎全部分布在2～10nm。海带基活性炭在碱性电解液中展现出优秀的电化学性能,当电流密度为0.1A/g时,其比电容高达366F/g,即使在电流密度为10A/g的条件下,活性炭比电容仍然高达329F/g,显示出良好的比电容性能和倍率性能。     

Controlled release study of carbaryl insecticide from calcium alginate and nickel alginate hydrogel beads

In this study, controlled release formulations for reducing environmental impact of pesticides have been produced by encapsulating as a model pesticide carbaryl (Carb) in the alginate beads. The various hydrogel bead formulations were prepared by the ionotropic crosslinking of sodium alginate (NaAlg) with calcium and nickel ions. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as carbaryl entrapment efficiency, particle size, equilibrium swelling degree, and carbaryl release kinetics, were determined. The effects of the bead preparation conditions such as crosslinker concentration and type, carbaryl/sodium alginate (Carb/NaAlg) ratio and percentage of NaAlg on the carbaryl release from the calcium alginate (Ca‐Alg) and nickel alginate (Ni‐Alg) beads were investigated in distilled water at 25°C. It was observed that carbaryl release from the Ca‐Alg beads was slower than that of Ni‐Alg beads. The release results indicated that carbaryl release from both of the Ca‐Alg and Ni‐Alg beads decreases with the increasing crosslinker concentration, Carb/NaAlg ratio and percentage of NaAlg. The highest carbaryl release was found to be 100% for the Ni‐Alg beads at 3 days whereas the lowest carbaryl release was found to be 67% for the Ca‐Alg beads at 21 days. The swelling measurements of the beads were also in consistent with the carbaryl release results. The carbaryl release from most of the bead formulations followed Case II transport. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Tunable transport of glucose through ionically‐crosslinked alginate gels: Effect of alginate and calcium concentration

Alginate beads have numerous biomedical applications, ranging from cell encapsulation to drug release. The present study focuses on the controlled release of glucose from calcium‐alginate beads. The effects of alginate concentrations (1–6 wt %) and calcium chloride concentrations (0.1–1.0M) on glucose release from beads were examined. It was found that the time required for complete glucose release from beads could be tuned from 15 min to over 2 h, simply by varying alginate and calcium chloride concentrations in beads. For calcium‐alginate beads with sodium alginate concentrations of 1–4 wt %, higher sodium alginate concentrations lead to more prolonged release of glucose and thus a smaller value of a rate constant k, a parameter shown to be proportional to the diffusion coefficient of glucose in the alginate gel. For beads with sodium alginate concentrations of 4–6 wt %, there was no statistically significant difference in k values, indicating a lower limit for glucose release from calcium‐alginate beads. Similarly, higher calcium chloride concentrations appear to extend glucose release, however, no conclusive trend can be drawn from the data. In a 50 : 50 mixture of calcium‐alginate beads of two different alginate concentrations (1 and 4 wt %), glucose release showed a two‐step profile over the time range of 20–50 min, indicating that the pattern and time of glucose release from beads can be tuned by making combinations of beads with varying alginate and/or calcium chloride concentrations. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Controlled release formulations of carbaryl based on copper alginate,barium alginate,and alginic acid beads

A controlled release system for reducing environmental impact was produced by encapsulating the pesticide carbaryl (Carb) in the alginate beads. The various bead formulations were prepared by using sodium alginate (NaAlg) as a polymer, CuCl₂, BaCl₂ as a crosslinking agent, and HCl as a linking agent. The surface morphology of prepared beads was characterized with scanning electron microscopy (SEM). SEM confirmed the spherical nature and surface morphology of the particles. Bead characteristics, such as Carb entrapment efficiency, particle size, swelling degree, and Carb release kinetics, were determined. The effects of crosslinker or linker concentration, type, and carbaryl/sodium alginate (Carb/NaAlg) ratio on Carb release from the beads were investigated for 20 days at 25°C. It was observed that Carb release from the beads increased with the increase of Carb/NaAlg ratio whereas decreased with the increase of crosslinker concentration. At the end of 20 days, the Carb release from alginic acid beads was found to be higher than that of copper alginate (Cu‐Alg) and barium alginate (Ba‐Alg) beads. The swelling measurements of the beads supported the release results. Release kinetics were described by Fickian and non‐Fickian approaches. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4245–4253, 2006     

膨润土对海藻酸钠/壳聚糖凝胶微球性能的影响

为了得到一种对啶虫脒具有高负载率和良好的缓释性能的农药载体,以膨润土作为吸附剂,利用壳聚糖的成膜性,采用挤出外源凝胶法制备了啶虫脒凝胶微球。并通过FTIR、SEM、TG、溶胀实验和释药实验对其结构、形貌和性能进行表征。结果表明,所制得的凝胶微球的粒径为1.42～1.71 mm,膨润土可提高微球粒径与球形度,使啶虫脒的载药率和包封率分别由原来的4.16%和36.36%提升为4.91%和63.01%。壳聚糖与海藻酸钠通过静电作用形成了聚电解质复合物,辅助了钙离子交联,使啶虫脒的载药率和包封率分别由原来的4.16%和36.36%提升为5.23%和54.29%。膨润土表面含有大量的羟基,与海藻酸钠和壳聚糖形成氢键作用,可有效抑制海藻酸钙的大量溶胀,提高其缓释性能。     

Dynamics of controlled release of potassium nitrate from a highly swelling binary polymeric blend of alginate and carboxymethyl cellulose

Highly water absorbing and homogeneous binary biopolymeric blends in bead form were prepared of calcium alginate and carboxymethyl cellulose by solution cast method. The prepared blends were evaluated for controlled delivery of KNO₃ taking it as a model agrochemical. The beads characterized by Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were used to investigate the molecular structure and morphology of beads. The swelling experiments were performed for different compositions of beads and at varying pH and temperature of the aqueous media. The release experiments were performed under static and varying experimental conditions and the release data obtained were conductometrically fitted to Ficks equation to evaluate diffusion coefficients of released KNO₃. The release results were further analyzed by Ficks power law equation, and the possible mechanisms of KNO₃ release were explored at different experimental conditions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of synthesis temperature on characteristics of PNIPAM/alginate IPN hydrogel beads

Poly(N‐isopropylacrylamide)/alginate interpenetrating polymer network hydrogel beads (IPN beads) were prepared via modified inverse emulsion polymerization, and the effect of the synthesis temperature on the characteristics of the IPN beads was investigated. Varying the synthesis temperature from 10 to 40°C led to slight differences in the FTIR and elemental analysis results, whereas significant differences in optical color, thermoresponsive behavior, and release properties of vitamin B₁₂ were observed. The IPN beads prepared at low temperature were transparent and exhibited a large and drastic thermoresponsive volume change. On the other hand, the IPN beads prepared at high temperature were opaque and exhibited a small and gradual thermoresponsive volume change. In addition, the diffusion coefficient in the IPN beads prepared at 10°C decreased with increasing solution temperature, whereas the diffusion coefficient in IPN beads prepared at 40°C increased with increasing solution temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41814.     

Polymeric sodium alginate interpenetrating network beads for the controlled release of chlorpyrifos

Novel polymeric sodium alginate (Na‐Alg) interpenetrating network (IPN) beads have been prepared by crosslinking Na‐Alg blend with gelatin (GE) or egg albumin (EA) using glutaraldehyde (GA) as the crosslinking agent. These beads were used for the controlled release of chlorpyrifos. The swelling experiments were performed in water at different temperatures, and these data were used to calculate the molecular mass (M_C) between crosslinks as well as diffusion coefficients. Diffusion coefficients calculated from desorption data were lower by about two orders of magnitude than those calculated from sorption results. Higher values of M_C were obtained for the gelatin‐based IPNs than the neat Na‐Alg and egg albumin‐based matrices. Size of the beads did not vary significantly either by the network or by increasing the exposure time to the crosslinking agent. The scanning electron microscopy (SEM) was used to understand the surface characteristics of the beads. Differential scanning calorimetry (DSC) indicated a molecular level dispersion of chlorpyrifos in the polymer matrix. The percentage entrapment efficiency showed a dependence on the type of network polymer as well as time of exposure to the crosslinking agent. The encapsulation efficiency decreased with an increase in time of exposure to the crosslinking agent. In vitro release experiments have been performed to follow the release kinetics of chlorpyrifos from the matrices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 911–918, 2002     

乙酸乙烯酯接枝改性海藻酸钙凝胶微球

为了降低海藻酸钙凝胶微球的溶胀度,以乙酸乙烯酯（VAc)对海藻酸钠进行自由基接枝共聚,进而制备具有较低溶胀度的聚乙酸乙烯酯改性海藻酸钙(Ca-SA-PVAc)凝胶微球。红外光谱表明,改性之后海藻酸钙的分子上生成新的化学键;热重分析表明,改性微球受热失水行为发生变化,热稳定性提高;扫描电镜表明,改性微球结构孔隙结构发达;接枝反应条件如反应温度、VAc的浓度、引发剂用量、海藻酸钠浓度、钙离子浓度及反应时间等对改性凝胶微球在生理盐水中的抗溶胀性具有不同程度的影响。通过改变反应条件以控制接枝反应参数,可以获得溶胀行为可控的改性海藻酸钙凝胶微球。     

Development of silver nanoparticles‐loaded calcium alginate beads embedded in gelatin scaffolds for use as wound dressings

Silver nanoparticles (AgNPs)‐loaded calcium alginate beads embedded in gelatin scaffolds were developed to sustain and maintain the release of silver (Ag⁺) ions over an extended time period. The UV irradiation technique was used to reduce Ag⁺ ions in alginate solution to AgNPs. The average sizes of AgNPs ranged between ca 20 and ca 22 nm. The AgNPs‐loaded calcium alginate beads were prepared by electrospraying of a sodium alginate solution containing AgNPs into calcium chloride (CaCl₂) solution. The AgNPs‐loaded calcium alginate beads were then embedded into gelatin scaffolds. The release characteristics of Ag⁺ ions from both the AgNPs‐loaded calcium alginate beads and the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were determined in either deionized water or phosphate buffer solution at 37 °C for 7 days. Moreover, the AgNPs‐loaded calcium alginate beads embedded in gelatin scaffolds were tested for their antibacterial activity and cytotoxicity. © 2014 Society of Chemical Industry