热敏性印迹水凝胶的合成及对甘草酸分离性能的研究

以甘草酸分子为印迹分子,N-异丙基丙烯酰胺作为温度响应性单体,和甲基丙烯酸共同为甘草酸的吸附性单体,在大量交联剂存在下,N-甲基吡咯烷酮中经自由基模板聚合,制备了一种热敏性印迹凝胶,对水凝胶的热收缩动力学进行了表征;用红外光谱证实了甘草酸分子与单体分子间的相互作用,以旁证其模板作用的存在：同时还与没有模板作用所合成的同种凝胶作了实施对比,发现模板聚合所得的水凝胶可以富集水溶液中的甘草酸,并对它表现出特殊的选择性分离作用,分配系数约为非模板聚合水凝胶的11倍。     

热敏性珠状水凝胶的合成及其萃取分离性能的研究

热敏性水凝胶是指凝胶在水中在某一临界温度附近,随温度的微小变化,水凝胶的体积会发生突跃性变化。该性能可用于极稀的生物物质水溶液的浓缩和萃取分离。本文研究了用反相悬浮聚合法合成N-异丙基丙烯酰胺(NIPA)和N、N-次甲基双丙烯酰胺(Bis)的珠状水凝胶以及水凝胶的分离性能。     

腐植酸钠/聚丙烯酰胺/粘土杂化水凝胶的研究

以过硫酸钾为引发剂、N,N′-亚甲基双丙烯酰胺为交联剂、丙烯酰胺单体和腐植酸钠、Laponite RD粘土为原料,用溶液聚合交联法合成了腐植酸钠/聚丙烯酰胺/粘土(SH-PAM-Clay)系列水凝胶.用场发射扫描电镜对其表面形貌进行了研究,并对水凝胶的吸水性和流变性能进行了测试和研究.结果表明这系列水凝胶都具有致密的网络结构和优良的吸水性能.     

凝胶渗透色谱柱填料研究现状

凝胶渗透色谱法(GPC)是19世纪60年代开发的一种分离技术,作为一种液相分离色谱,其具有对流动相的要求不高、实验条件温和、重现性好、分析速度快、溶质回收率高等优点。这些优点使凝胶渗透色谱具有独特的分离效果,因此得到迅速发展并广泛用于石油化工、生物医药、食品卫生、环境监控等领域。该文对凝胶渗透色谱柱填料(如聚丙烯酰胺凝胶、聚苯乙烯凝胶等)的合成、性能以及应用进行综述,并对近年来出现的新型柱填料进行简要介绍。     

手性温敏凝胶Poly(NIPAM-co-AAc-L-Trp)的制备及性能

利用L-色氨酸(L-Trp)为手性源,经酯化、缩合等反应制备手性单体AAc-L-Trp,进而在交联剂N,N’-亚甲基双丙烯酰胺(MBAA)和引发剂偶氮二异丁腈(AIBN)的作用下,与N-异丙基丙烯酰胺(NIPAM)发生自由基共聚制备了一种可用于手性拆分的新型手性温敏水凝胶Poly(NIPAM-co-AAc-L-Trp),其结构经IR确证.通过对其温敏性研究发现,相比于PNIPAM凝胶,疏水性手性单体的引入使Poly(NIPAM-co-AAc-L-Trp)凝胶的温敏性下降,LCST随着手性单体含量的增加而降低.以DL-苯丙氨酸为模型药物对其手性识别和拆分性能进行研究,结果表明,手性温敏凝胶可选择性地吸附D-型对映体,且吸附量随着手性单体含量增加而增加;提高温度(45°C)有利于手性温敏凝胶对DL-苯丙氨酸的拆分.     

多孔聚N-异丙基丙烯酰胺水凝胶的制备与缓释性能

以N-异丙基丙烯酰胺(NIPA)、N,N-亚甲基双丙烯酰胺(MBA)和聚乙二醇(PEG)为原料,以60Co-γ射线为放射源制备了快速响应聚N-异丙基丙烯酰胺(PNIPA)多孔水凝胶。用红外光谱分析了水凝胶的结构,并测定了水凝胶的溶胀动力学、退溶胀动力学和平衡溶胀率。结果表明,PEG分子仅在聚合交联过程中充当成孔剂,不参与反应,反应后可被除去;水凝胶具有明显的温度敏感性,成孔剂的添加提高了水凝胶的溶胀性能和LCST。选用阿司匹林为模型药物,对水凝胶的药物缓释性能进行了初步研究。     

分离亲水气单胞菌外毒素的聚丙烯酰胺凝胶色谱填料

由丙烯酰胺和甲叉丙烯酰胺在水油悬浮液中共聚得到聚丙烯酰胺凝胶 (ZSP)系列 ,并用红外、溶剂吸收实验等对合成的ZSP的结构进行了研究。以商品葡聚糖凝胶SephadexG 10 0为对照 ,研究了ZSP 10对使中华鳖致病的亲水气单胞菌外毒素的分离性能。结果表明 :ZSP 10对毒素分离效率高 ,洗脱峰不拖尾 ,且结构和膨胀度可调 ,成本低廉 ,不易染菌霉变。经SephadexG 10 0和ZSP 10提纯的外毒素蛋白均保留了生物活性。根据SDS -PAGE的分析 ,确认经提纯的毒素蛋白的分子量为 3.2× 10 4     

温度敏感水凝胶包覆长周期光纤光栅传感器研究

以N-异丙基丙烯酰胺(NIPAM)为单体、N,N'-亚甲基双丙烯酰胺(MBAA)为交联剂、安息香二甲醚(DMPA)为引发剂,利用紫外光引发聚合制备了一系列温度敏感性聚(N-异丙基丙烯酰胺)(PNIPAM)水凝胶,并对其性能进行了测定.结果表明,PNIPAM水凝胶的平衡膨胀比随着交联程度的变化而改变.当交联程度适当时,水凝胶可具有最大的溶胀比.在此研究基础上,利用浸渍提拉法在长周期光纤光栅(LPFG)包层外制备了PNIPAM水凝胶薄膜包覆层.研究了得到的LPFG传感器对温度和湿度的响应性,该类型传感器表现出对温度的灵敏响应性.     

无皂种子分散聚合法制备单分散双重响应性微凝胶

以N-异丙基丙烯酰胺及2-乙烯基吡啶为主要单体, 采用无皂种子分散聚合法制备了单分散的、具有温度及pH双重响应性能的核-壳结构微凝胶, 并以扫描电镜及动态激光光散射等手段对微凝胶粒子的结构和性能进行了研究. 溶胀行为研究表明, 微凝胶粒子具有独立的互不干扰的温度及pH敏感性能, 其体积相变温度与纯聚N-异丙基丙烯酰胺(PNIPAM)凝胶基本一致, 说明局部分布的弱电离单体不会对PNIPAM凝胶的体积相变温度造成影响.     

基于壳聚糖/聚丙烯酸/纳米银的高强抗菌水凝胶

首先以丙烯酸(AA)和壳聚糖(CS)为单体、N,N′-亚甲基双丙烯酰胺(MBA)为交联剂,通过光聚合法制备了CS/PAA双网络水凝胶,然后将Ag~+以硝酸银的形式分散在水凝胶中并通过紫外光辐照获得CS/PAA/纳米银复合水凝胶,并对复合水凝胶的抗菌性能进行研究。采用红外光谱对其结构进行表征,研究单体含量对水凝胶力学性能以及溶胀行为的影响。结果表明,当丙烯酸质量分数为20%,壳聚糖质量分数为5%的情况下,水凝胶的拉伸性能最优。此外,纳米银的引入有效提高了水凝胶的抗菌性能。     

利用双水相体系的温度诱导效应萃取甘草酸

利用双水相分配技术结合温度诱导效应提取甘草酸，研究甘草酸单铵盐在环氧乙烷－环氧丙烷共聚物（EOPO）／混合磷酸钾（KHP）体系中的分配行为，通过实验确定了最佳体系：EOPO L64浓度为28（wt)%，K2HPO4浓度为32（wt）％。甘草酸单铵盐最大总收率达68.4%，为工业上采用双水相技术提取干草酸提供了一种新途径。     

Semi‐interpenetrating polymer networks composed of poly(N‐isopropyl acrylamide) and polyacrylamide hydrogels

Three series of semi‐interpenetrating polymer networks, based on crosslinked poly(N‐isopropyl acrylamide) (PNIPA) and 1 wt % nonionic or ionic (cationic and anionic) linear polyacrylamide (PAAm), were synthesized to improve the mechanical properties of PNIPA gels. The effect of the incorporation of linear polymers into responsive networks on the temperature‐induced transition, swelling behavior, and mechanical properties was studied. Polymer networks with four different crosslinking densities were prepared with various molar ratios (25:1 to 100:1) of the monomer (N‐isopropyl acrylamide) to the crosslinker (methylenebisacrylamide). The hydrogels were characterized by the determination of the equilibrium degree of swelling at 25 °C, the compression modulus, and the effective crosslinking density, as well as the ultimate hydrogel properties, such as the tensile strength and elongation at break. The introduction of cationic and anionic linear hydrophilic PAAm into PNIPA networks increased the rate of swelling, whereas the presence of nonionic PAAm diminished it. Transition temperatures were significantly affected by both the crosslinking density and the presence of linear PAAm in the hydrogel networks. Although anionic PAAm had the greatest influence on increasing the transition temperature, the presence of nonionic PAAm caused the highest dimensional change. Semi‐interpenetrating polymer networks reinforced with cationic and nonionic PAAm exhibited higher tensile strengths and elongations at break than PNIPA hydrogels, whereas the presence of anionic PAAm caused a reduction in the mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3987–3999, 2004     

Aqueous polyurethane-alginate compositions: Peculiarities of behavior and performance

A series of polyurethane-alginate (APU/AG) compositions with pH/temperature-responsive character and regulated viscosity were obtained by adding different quantities of sodium alginate into an aqueous polyurethane anionic dispersion. Rheological, thermoresponsive, mechanical properties and swelling behavior dependencies on composition have been determined. APU/AG compositions reached equilibrium swelling and deswelling states within about 60 min. They display non-Newtonian flow and posses thixotropic properties. The strength of the films increases after their treatment with CaCl₂ at the expense of cross-linking of alginate with divalent calcium ions and of forming an alginate network.     

几类甲基丙烯酸pH—敏感水凝胶的溶胀行为研究

本文合成了以甲基丙烯酸为基础的各类ｐＨ敏感型水凝胶,并研究它们的溶胀行为。初步探索了水凝胶的组成与其ｐＨ敏感的关系,比较了阴离子型水凝胶、阳离子型水凝胶和两性水凝胶的溶胀热力学动力学行为,得出了两性水凝胶在整个ｐＨ范围内都有一定的溶胀比,且在ｐＨ中性时,其溶胀速率要高于相应的阴离子型和阳离子型水凝胶。     

Stimuli-responsive hydrogels based on polysaccharides incorporated with thermo-responsive polymers as novel biomaterials

In recent years, intelligent hydrogels which can change their swelling behavior and other properties in response to environmental stimuli such as temperature, pH, solvent composition and electric fields, have attracted great interest. The hydrogels based on polysaccharides incorporated with thermo-responsive polymers have shown unique properties such as biocompatibility, biodegradability, and biological functions in addition to the stimuli-responsive characters. These "smart" hydrogels exhibit single or multiple stimuli-responsive characters which could be used in biomedical applications, including controlled drug delivery, bioengineering or tissue engineering. This review focuses on the recent developments and future trends dealing with stimuli-responsive hydrogels based on grafting/blending of polysaccharides such as chitosan, alginate, cellulose, dextran and their derivatives with thermo-sensitive polymers. This review also screens the current applications of these hydrogels in the fields of drug delivery, tissue engineering and wound healing.     

Preparation and characterization of a novel IPN hydrogel memberane of poly(N-isopropylacrylamide)/carboxymethyl chitosan (PNIPAAM/CMCS)

A novel type of interpenetrating polymer networks (IPN) hydrogel membrane of poly(N-isopropylacrylamide)/carboxymethyl chitosan (PNIPAAm)/(CMCS) was prepared, and the effects of the feed ratio of components, swelling medium and irradiation dose on the swelling and deswelling properties of the hydrogel was systematically studied. The results showed that the introduction of CMCS did not shift the LCST (at 32 °C), which is similar to the pure PNIPAAm. The lowest swelling ratio was at pH 2. There was little influence of irradiation dose on the thermo- and pH-sensitivity of the IPN hydrogel, increasing dose only decreased the swelling ratio. The PNIPAAm:CMCS=1:4 w/w hydrogel was not thermo-sensitive in distilled water, whereas it showed a discontinuous volume phase transition in pH 2 and a continuous one in pH 8 buffer. Consequently, a combination of pH and temperature can be coupled to control the responsive behavior of these hydrogels.     

Synthesis and Characterization of Crosslinked Hyperbranched Polyglycidol Hydrogel Films

Hyperbranched polyglycidol (PGLD) was synthesized via anionic ring‐opening polymerization of glycidol using a special anionic initiator with multiple initiation sites. The resultant polymers were characterized by ¹H and ¹³C‐NMR spectra for confirming their structures, which consisted of linear, hyperbranched and dendritic structures. Molecular weight characteristics were determined by means of the gel permeation chromatography (GPC). With the intention of investigating the possibility of broad applications, PGLD hydrogel films were prepared using various crosslinking agents, i.e., glutaraldehyde and some dicarboxylic acids, and their physical properties such as swelling behavior and tensile (or Young's) modulus were measured and compared.     

Temperature-responsive chromatography using poly(N-isopropylacrylamide) hydrogel-modified silica.

Poly(N-isopropylacrylamide) (PNIPAAm) has the sharpest phase transition of the class of thermo-sensitive N-alkyl acrylamide polymers. We developed a new method of HPLC using packing materials modified with cross-linked poly(N-isopropylacrylamide) (PNIPAAm) hydrogel. A temperature-responsive surface was prepared by polymerization of NIPAAm in the presence of a cross-linker on the silica support. The surface properties and functions of the stationary phases change in response to the external temperature. Therefore it easily changes the interaction of a solute with the surface with a constant aqueous mobile phase. A temperature-responsive elution behavior was observed on the separation of steroids and PTH-amino acids. The method is expected to be applicable to separation in the pharmaceutical and biomedical fields.     

Investigation on properties of re-dispersible cationic hydrogel nanoparticles

P(DMAEMA-g-EG) cationic hydrogel nanoparticles (CHNPs) were prepared by distillation-dispersion copolymerization of poly(ethylene glycol) methyl ether methacrylate (MPEGMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA) using acetonitrile (AN) as dispersion medium. The results of FTIR spectra indicate that the composition of P(DMAEMA-g-EG) CHNPs is consistent with the designed structure. The TEM image shows that P(DMAEMA-g-EG) CHNPs are of spherical morphology before and after swelling. The investigations on the properties of P(DMAEMA-g-EG) CHNPs indicate that P(DMAEMA-g-EG) CHNPs have pH-, ionic strength- and thermo-sensitive characters. This type of P(DMAEMA-g-EG) CHNP is very promising as environment-sensitive drug carriers.     

Liposomes as carriers in electrokinetic capillary chromatography

Liposomes are small membrane-enclosed vesicles composed of either natural or synthetic lipids. Their size can be adjusted on a wide scale and they can be made with well-defined compositions. While liposomes have been extensively used as model biomembranes they have also gained a considerable degree of attention as carriers for drugs as well as for genetic material. The physical properties of liposomes are critically dependent on their chemical composition. In this study liposomes were applied as pseudostationary phases in electrokinetic capillary chromatography. Various negatively charged liposomes, consisting of mixtures of zwitterionic and anionic lipids, were investigated. Major emphasis was put on clarifying the effects of the total lipid concentration, the lipid molar ratio, the lipid head group, and the buffer on the capillary electrophoretic separation of neutral analytes. In addition, the influence of the physical state of the membrane, ie., gel vs. fluid, on the separation was investigated. Corticosteroids were applied as model analytes.