低分子量N,O-羧甲基壳聚糖的合成及吸湿保湿性能

采用不同反应温度、反应时间和低分子量壳聚糖与氯乙酸摩尔比,在非均相反应体系中合成了不同取代度的低分子量N,O-羧甲基壳聚糖。当反应温度为60°C,反应时间为4h,低分子量壳聚糖与氯乙酸投料比为1∶1.5时,目标产物的取代度可达71%。吸湿保湿性能测定表明:取代度越大,低分子量N,O-羧甲基壳聚糖的吸湿保湿性越好,在相对湿度为81%,取代度从27%增大到71%时,其吸湿性从32.14%增大到37.27%,保湿性从310.72%增大到348.69%。     

N,O-羧甲基壳聚糖修饰对L-天门冬酰胺酶血浆半衰期及其他性质影响

将具有抗癌作用的L-天门冬酰胺酶用N,O-羧甲基壳聚糖进行化学修饰,以降低酶的抗原性,提高其在体内的半衰期.实验结果表明,修饰酶的表观K_m值与自由酶相差不多,分别为2.6×10~(-4)mol/L和2.2×10~(-4)mol/L(20℃),而抗胰蛋白酶和糜蛋白酶水解能力有很大提高.酶经修饰后抗原性大大降低,且修饰剂分子量越高,降低抗原性的效果越好.自由酶在兔体内的半衰期为1.2h,而修饰酶为40h,提高了33倍.     

O-羧甲基壳聚糖的制备及应用研究进展

O_羧甲基壳聚糖是壳聚糖的一种衍生物 ,具有比壳聚糖更优良的特性 ,有着更广阔的应用前景。本文对它的制备、性质、应用 ,特别是其在药物释放及基因治疗方面应用的研究进展进行了综述。     

O-羧甲基黄原酸壳聚糖合成及应用研究

以壳聚糖(CS)为原料,先制备出O-羧甲基壳聚糖(OCMC),再和二硫化碳在碱性条件下合成O-羧甲基黄原酸壳聚糖(CXCS)。通过产物的含硫量对碱浓度、投料比和反应时间等因素进行了优化,采用固体13CNMR和SEM表征其结构。结果表明,合成CXCS的最佳条件为碱浓度10%,投料比1∶1,室温反应3h,产品的含硫量达10.22%。最后研究了CXCS对水溶液镉离子的吸附性能,结果表明CXCS具有优异的吸附性能,其最大吸附量可达288.5 mg/g,是壳聚糖吸附量的2.65倍。红外分析结果表明吸附主要依靠结构中的羧基和黄原酸基团。     

O-羧甲基壳聚糖纳米微粒制备及对Ni~(2+)吸附研究

将壳聚糖与氯乙酸反应,通过控制反应条件制备了取代度为0.71的O-羧甲基壳聚糖,将改性后的O-羧甲基壳聚糖与多聚磷酸钠反应,制备了粒径分布在370-710nm的O-羧甲基壳聚糖纳米微粒,透射电镜观察表明该微粒呈球状,平均粒径为450nm.在此基础上研究了O-羧甲基壳聚糖纳米微粒对工业电镀镍废水Ni~(2+)吸附性能,考察了溶液pH、Ni~(2+)起始浓度、平衡吸附时间、粒径等因素的影响,结果表明:O-羧甲基壳聚糖微粒最佳吸附条件是Ni~(2+)溶液pH为8.0、Ni~(2+)溶液起始浓度为33.28mg/ml、平衡吸附时间为0.5h、粒径较小的O-羧甲基壳聚糖纳米微粒对Ni~(2+)的吸附量要大于粒径较大的吸附量.     

离子凝胶反应法制备壳聚糖/N,O-羧甲基壳聚糖微球

以一氯乙酸与壳聚糖反应形成N,O-羧甲基壳聚糖两性聚电解质,分光光度法测定其等电点IEP=2．86。以此两性聚电解质与壳聚糖可以在一定条件下形成微球,光学显微镜和电子显微镜测试表明,控制两种聚电解质配比可以制备不同粒径大小的微球,而超声功率对微球粒径的影响较小。红外光谱测试表明微球中N,O-羧甲基壳聚糖羧基以羧酸根形式存在,分光光度与电导法联合测定表明两种聚电解质以离子凝胶作用形成微球,其最佳制备条件为IEP（CM-CHITOSAN）〈pH〈pKa（CS）,在此较宽的pH值范围内微球可稳定存在。     

O-羧甲基壳聚糖稀土配合物的制备及与牛血清白蛋白的作用

合成了O-羧甲基壳聚糖与稀土La(Ⅲ)、Nd(Ⅲ)的配合物,并研究了与牛血清白蛋白(BSA)的相互作用。BSA紫外吸收光谱随配合物浓度的增加而表现出明显的减色效应和较小的蓝移;配合物对BSA的荧光具有较强的猝灭作用。     

羧甲基壳聚糖/明胶共混膜的结构表征与吸湿保湿性

壳聚糖通过羧甲基化得到水溶性N，O-羧甲基壳聚糖，并将其配制成4Wt％水溶液，与4Wt％明胶水溶液共混，成功制得了羧甲基壳聚糖／明胶共混膜。采用红外光谱、x射线衍射、扫描电镜对共混膜进行结构表征，结果表明，共混膜中羧甲基壳聚糖和明胶分子间存在着较强的相互作用及良好的相容性。通过共混膜的力学性能测试，发现当羧甲基壳聚糖含量为20％时，共混膜的抗张强度达到最大值(75MPa)，分别比单独的羧甲基壳聚糖(45MPa)和明胶(43MPa)提高了66．7％和74％。经过吸湿和保湿性能测试，发现当羧甲基壳聚糖含量为80％时，吸湿率和保湿率分别为33．4％和69．2％，比单独的明胶膜分别提高了1．8倍和2．1倍。     

O-羧甲基壳聚糖稀土配合物的抑菌活性及与DNA的相互作用

用体外抑菌法研究了O-羧甲基壳聚糖镧、O-羧甲基壳聚糖钕配合物对大肠杆菌(E.coli)、金黄色葡萄球菌(St.aureus)、阴沟肠杆菌(E.cloacae)、枯草芽孢杆菌(B.subtilis)、粪肠杆菌(E.faecalis)和肺炎克罗伯杆菌(S.pneumoniae)的抑菌活性。采用紫外光谱研究了两种O-羧甲基壳聚糖稀土配合物与小牛胸腺DNA的相互作用。结果表明:O-羧甲基壳聚糖稀土配合物均有抑菌活性,且O-羧甲基壳聚糖稀土配合物与DNA以静电作用为主,能使DNA双螺旋结构破坏。     

两亲性羧甲基壳聚糖衍生物的表面活性研究

将羧甲基壳聚糖与烷基缩水甘油醚在碱性条件下反应,合成了一系列新型的两亲性化合物(2-羟基-3-烷氧基)丙基-羧甲基壳聚糖,对其表面性质的研究结果表明,对同一衍生物,在所研究范围内,取代度越高,降低表面张力的能力及效率越高;对同一取代度的不同衍生物,疏水链越长,降低表面张力的能力越强;对链较短和取代度较大的衍生物,如(2-羟基-3-丁氧基)丙基羧甲基壳聚糖(HBP-CMCHS),在外加电解质存在时溶液的表面张力曲线出现2个转折点,表明可能有分子内胶束形成;而对链较长的衍生物,如(2-羟基-3-十二烷氧基)丙基羧甲基壳聚糖(HDP-CMCHS),则无明显的临界胶束浓度,有外加电解质时表面张力曲线也未出现2个转折点.     

过渡金属离子液体EMIFeCl3的性质研究

在干燥高纯氩气氛的手套箱内, 直接将摩尔比为1∶1的高纯无水FeCl3与氯化1-甲基-3-乙基咪唑(EMIC)混合, 得到棕色透明的离子液体EMIFeCl4. 在293.15~343.15 K温度范围内测定了该离子液体的密度和表面张力. 利用Glasser经验方程和空隙模型研究了EMIFeCl4的性质, 并与离子液体EMIAlCl4进行比较, 指出空隙模型具有一定的合理性.     

Synthesis and characterization on a novel series of protic pyrrolidinium surfactants

<正>A novel series of protic tertiary pyrrolidinium surfactants were prepared and characterized by different techniques.These compounds show good conductivity and efficient ability to reduce surface tension.Thermogravimetric analysis proves their high thermal stability at decomposition temperatures over 250℃.Their lyotropic and thermotropic liquid crystalline properties are also discussed.     

N,N-二异丙基乙二胺盐酸盐的合成

N;N-二异丙基乙二胺盐酸盐的合成;二异丙胺;环氧乙烷;N;N-二异丙基乙醇胺;N;N-二异丙基氯乙胺;N;N-二异丙基乙二胺     

Sequence identification,structure prediction and validation of tannase from Aspergillusniger N5-5

Tannases produced by filamentous fungi are in a family of important hydrolases of gallotannins and have broad industry applications. But until now, the 3-D structures of fungi tannases have not been reported. The protein sequence deduced from the cDNA sequence obtained using RT-PCR amplification was identified as tannase through sequence alignment and phylogenetic analysis. Structure models based on the tannase sequence were collected using I-TASSER, and the model with the best match to the surface charge density-pH titration profile was selected as the final structure for tannase from Aspergillusniger N5-5. This work provides an effective method for protein structure research. The structure constructed in this work should be very important to understand the enzyme bioactivities and further developments of fungi tannases.     

聚(N,N-二甲基苯胺)的质子化研究

研究了聚(N,N-二甲基苯胺)在硫酸和三氯醋酸水溶液中的质子化行为,对其吸收光谱和核磁共振谱的研究发现,聚(N,N-二甲基苯胺)在不同酸度下存在两种质子化状态:在强酸体系中质子加在侧基氮原子上,在中等酸性体系中质子加在主链的苯环上.     

Synthesis and SAM formation of water soluble functional carboxymethylcelluloses: thiosulfates and thioethers

Functional thiomethyl and thiosulfate derivatives of carboxymethylcellulose (CMC, DS = 0.9) were synthesized by nucleophilic displacement reactions. Alkylation of CMC by allyl glycidyl ether took mainly place at the primary positions of the cellulose backbone and yielded a 6-O-(3-allyloxy-2-hydroxypropyl)-CMC 1 with a partial DS of 3-allyloxy-2-hydroxypropyl substituents DSallyl of up to 0.43. Addition of tetrathionate to the allyl groups gave rise to 6-O-(2,3-bis(thiosulfato)propoxy-2-hydroxypropyl)-CMC 2. As the addition of tetrathionate was sluggish and incomplete, alternatively bromine was added and the resulting dibromide was substituted by thiosulfate. A 40% conversion of the allyl groups was achieved by this two-step procedure. On the other hand, the addition of bromine to 1 in aqueous solution almost quantitatively yielded the bromohydrin derivative which was converted by displacement reaction with thiosulfate to 6-O-(2-hydroxy-3-thiosulfatopropoxy-2-hydroxypropyl)-CMC 4. 6-Thiomethyl-6-deoxy-CMC 6 was synthesized by displacement reaction of 6-O-tosylcellulose with sodium methylsulfide and subsequent carboxymethylation of the cellulose backbone. A partial DS of thiomethyl substituents DSThM=0.65 exclusively at the primary positions was obtained. All functional CMC derivatives, 2, 4, and 6 were readily available in gram quantities, rather stable and highly water soluble for pH > 3. On gold surfaces they form self-assembled monolayers (SAMs) with thicknesses of 1.2 to 2.4 nm as determined by surface plasmon resonance (SPR).     

Synthesis,Characterization, and Surface Properties of Cationic Gemini Surfactants

New pyridinium gemini surfactants have been synthesized by esterification of renewable fatty acids with mercaptoethanol furnishing respective esters (mercaptomethyl decanoate, mercaptomethyl dodecanoate, mercaptomethyl tetradecanoate, mercaptomethyl hexadecanoate) followed by their subsequent treatment with 4-dimethyl amino pyridine resulting in the formation of title gemini surfactants: 1-(5-(decanoyloxy)-2-hydroxypentyl)-4-((5-(decanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (9), 1-(5-(dodecanoyloxy)-2-hydroxypentyl)-4-((5-(dodecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (10), 1-(5-(tetradecanoyloxy)-2-hydroxypentyl)-4-((5-(tetradecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (11), and 1-(5-(hexadecanoyloxy)-2-hydroxypentyl)-4-((5-(hexadecanoyloxy)-2-hydroxypentyl)dimethyl ammonio)pyridin-1-ium chloride (12). Their identifications are based on infrared, ¹H NMR, ¹³C NMR, distortionless enhanced polarization transfer, co-relational spectroscopy (COSY), and mass spectral studies. Their surface active properties are also evaluated on the basis of surface tension and conductivity measurements. Thermal stability of these long chain cationic gemini surfactants have been measured by thermal gravimetric analysis under nitrogen atmosphere.     

N,N′-二-(2-吡啶基)苝四羧酸二酰亚胺的合成及性能研究

合成了N,N′ 二 (2 吡啶基)四羧酸二酰亚胺,并纯化、调晶.对产物进行了元素分析和IR光谱研究(环状二酰亚胺的CO以双峰1708.8cm-1、1664 5cm-1).α晶型产物溶液的紫外可见光谱(最大吸收波长为526.00nm)和荧光光谱(最大发射波长为538.0nm)存在很好的镜像对称关系.薄膜紫外可见光谱图在450—570nm范围内,α晶型比β晶型有较强的吸收峰.X粉末衍射也反映出α晶型在2θ为25.5°、26.3°上的衍射峰强度分别为1954、2603.α、β晶型分别作为电荷产生材料制得的功能分离型有机光导体,在光源波长λ=532nm曝光下,测得含α的感光体达到饱和电位的时间45s、半衰曝光量5.7μJ/cm2、残余电位22V等数据.测得含β的感光体达到饱和电位的时间49s、半衰曝光量9.9μJ/cm2、残余电位22V等性能数值.     

Modification of polybenzimidazole: Synthesis and thermal stability of poly(N1-methylbenzimidazole) and poly(N1,N3-dimethylbenzimidazolium) salt

Poly(N₁,N₃-dimethylbenzimidazolium) (PDMBI) salt and poly(N₁-methylbenzimidazole) (PMMBI) were synthesized by methylation of commercial polybenzimidazole [poly-2,2′-(m-phenylene)-5,5′-bibenzimidazole (PBI)]. First, the N-lithium salt of polybenzimidazole was formed by treating polybenzimidazole solution of 1-methyl-2-pyrolidinone (NMP) with lithium hydride at 80°C for 18 h. Ninety percent substitution of PMMBI was obtained by treating the N-lithium salt of PBI with equimolar ratio of iodomethane at room temperature. Upon addition of excess iodomethane to the lithium salt of PBI at 80°C, a polymer was formed that showed 100% substitution on the N₁ nitrogen and about 30% substitution of the methyl group on the N₃ nitrogen in the form of N₁,N₃-dimethylbenzimidazolium iodide salt [PDMBI (30%)]. The content of the benzimidazolium iodide salt was increased to about 90% by dissolving PDMBI (30%) in dimethyl sulfoxide (DMSO) and re-treating with excess iodomethane at 80°C overnight. The modified PBI polymers were characterized by NMR and FTIR. The modified PBI differed in solubility from PBI. PMMBI could be easily dissolved in NMP and PDMBI in DMSO at room temperature. The solution of PDMBI could be mixed with water in all proportions without precipitation. PDMBI could be also dissolved directly in a mixture of DMSO and water (1 : 1). Typical polyelectrolyte behavior of viscosity was found in solution of PDMBI (30%) and PDMBI (90%) when DMSO and a mixture of DMSO and water were used as solvents. A salt effect on viscosity was also found in the mixed solvent solution. Thermogravimetric analysis (TGA) showed that the methyl group on the imidazole ring was unstable above 180°C under nitrogen. When PDMBI was heated under nitrogen, one of the methyl groups was lost with the counterion to result in a neutral PMMBI. © 1993 John Wiley & Sons, Inc.     

STABILITY OF POLY（N,N＇-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE） MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.