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1.
在制备水溶性较好的O-季铵化壳聚糖基础上,进一步与糠醛反应制备O-季铵化-N-呋喃亚甲基壳聚糖席夫碱及还原产物O-季铵化-N-呋喃亚甲基壳聚糖衍生物,用FTIR、1H NMR、EA(元素分析)、TG(热重分析)对产物进行表征。测定产物的最低抑菌浓度和抑菌率,并与O-季铵化-N-苯亚甲基壳聚糖席夫碱的抑菌效果进行比较。结果表明,产物对革兰氏阳性菌S.aureus的抗菌效果优于革兰氏阴性菌E. coli,在pH值5.5的条件下抗菌效果优于pH 值7.2。并且O-季铵化-N-呋喃亚甲基壳聚糖的抗菌效果>O-季铵化-N-呋喃亚甲基壳聚糖席夫碱>O-季铵化-N-苯亚甲基壳聚糖席夫碱 > O-季铵化-壳聚糖。研究表明,含呋喃杂环的壳聚糖衍生物的抗菌活性明显优于不含杂环的壳聚糖衍生物。 相似文献
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以壳聚糖为原料,通过反相悬浮交联法制备交联壳聚糖树脂,将其用于吸附Cr(Ⅵ),考察了吸附时间、溶液pH、树脂用量、Cr(Ⅵ)的初始浓度和介质等因素对吸附的影响。实验结果表明,吸附平衡时间为20 min,最佳吸附pH为6.0,最佳用量为10 mg,Cr(Ⅵ)起始浓度为6 mg/mL,介质对吸附的影响大小顺序:Cu2+〉Na+。重复使用3次,再生性能好。 相似文献
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Novel chitosan-N-inulin graft copolymers with different degree of substitution (DS) of chitosan were synthesized via water-soluble 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide mediated reaction. Chemical structure and composition of the chitosan derivatives was confirmed by chemical analysis, FT-IR, XPS, 1H and 13C NMR spectroscopy, and potentiometry. Chitosan–inulin copolymers were high-molecular-weight hydrophilic products soluble in water in a wide pH range forming extraordinary viscous solutions. Intrinsic viscosity of N-modified chitosans was sharply suppressed by added electrolyte and had tendency to decrease at higher DS of chitosan. pKα values of the chitosan–inulin copolymers determined from potentiometric titration data using Henderson–Hasselbalch equation were in the range 6–7 slightly increasing at higher DS. Novel water-soluble chitosan copolymers retained cationic properties of chitosan and could be used as surface conditioners. 相似文献
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Tohru Saitoh Yusuke Sugiura Kotaro Asano Masataka Hiraide 《Reactive and Functional Polymers》2009,69(10):792-796
Chitosan-conjugated thermo-responsive polymers (PNIPAAm-CSs) containing 2.0–8.7% (w/w) chitosan were readily synthesized by the condensation of chitosan and poly(N-isopropylacrylamide-co-acrylic acid) with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. PNIPAAm-CSs were water-soluble at 30 °C, while they deposited above the lower critical solution temperature (LCST, ca. 34 °C in 50 mM sodium phosphate, pH 6.8). Tyrosinase-induced phenol oxidation was performed in the dilute aqueous polymer solution at 30 °C for the rapid binding of oxidized compounds to the amino moiety of PNIPAAm-CS. By heating and shaking the solution, the polymer containing highly concentrated oxidized compounds deposited and agglutinated to a condensed coagulate. Increasing polymer concentration and chitosan content in the polymer increased the removal of phenol and its oxidized compounds. When 1.0 g of PNIPAAm-CS containing 8.7% chitosan was employed for treating 1 l of contaminated water, the concentration of phenol (19 mg l−1) was reduced below the detection limit (0.08 mg l−1) within 2 h. 相似文献
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The hydroxymethyl groups of 2‐amino‐2‐deoxy‐D ‐glucose units in chitosan were selectively oxidized to carboxyl groups with NO2 gas to form 6‐carboxy‐chitosan in aqueous 0.5 mol/L acetic acid. In optimal conditions, the 52.5% hydroxymethyl groups in chitosan could be converted into carboxyl groups. When the pH value of the solution is lower than 4.0 or more than 5.4, 6‐carboxy‐chitosan has common characteristics of a polycation or polyanion electrolyte, respectively, and when the pH value of the solution is 4.0—5.4, 6‐carboxy‐chitosan has common characteristics of an amphoteric polyelectrolyte. 6‐Carboxy‐chitosan has same macromolecular backbones as chitosan, and its isoelectric point (pI) value is 4.9. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1126–1130, 2004 相似文献
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A. I. Azarova P. A. Perminov N. R. Kil’deeva S. N. Mikhailov L. V. Vladimirov 《Fibre Chemistry》2011,43(2):129-133
The possibility of using oxidized nucleotides and nuclosides as cross-linking reagents for preparing chitosan hydrogels with
a broad range of applications was examined. It was found that the ratio of dialdehyde to chitosan amine and the reaction medium
pH affected gel formation in aqueous acetic acid solutions of chitosan in the presence of the cross-linking reagents glutaraldehyde
and oxidized nucleic acid derivatives. IR spectra of chitosan and its derivatives were recorded and characterized. Immobilization
of the proteolytic enzyme trypsin in chitosan films on fibrous materials was studied. 相似文献
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以碳酸钠为催化剂,室温下制备了水溶性的马来酰化壳聚糖.由红外光谱分析的结果说明了马来酸酐成功接枝到壳聚糖分子上,且酰化反应后的壳聚糖的热性能较壳聚糖有了很大提高.采用MPT-2自动滴定仪和Nano-ZS粒度仪对不同pH值下的颗粒粒径和Zeta电位进行测定,发现存在2个等电点:pH=2.24和pH=5.45. 相似文献
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以水溶性壳聚糖(CS)与稀土离子La3+, Nd3+, Sm3+, Eu3+和Dy3+在常温和pH值为4~5的条件下制备了水溶性壳聚糖稀土配合物CS-La, CS-Nd, CS-Sm, CS-Eu和CS-Dy. 并运用FT-IR, UV和TG-DTA对其配合物进行表征,并研究了配体和配合物的热稳定性及配合物的抑菌活性. 结果表明,5种配合物均有选择性抑菌性能;其对大肠杆菌和金黄色葡萄球菌均有很好的抑菌作用;其对5种菌的最小抑菌浓度(MIC)为120~500 mg/mL,低于800 mg/mL,且抑菌效果明显优于单独的壳聚糖和稀土硝酸盐. CS-Sm对大肠杆菌的抑菌性最好,MIC为125 mg/mL;而CS-Nd和CS-Sm对金黄色葡萄球菌的抑菌性最强,MIC均为120 mg/mL. 相似文献
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Stimuli responsive gels based on interpenetrating network of chitosan and poly(vinylpyrrolidone) 总被引:1,自引:0,他引:1
New spherically shaped crosslinked IPN hydrogels based on chitosan and poly(vinylpyrrolidone) were prepared. The IPN hydrogels were synthesized in two steps: (1) chitosan (CHT) crosslinked beads were obtained by reaction of chitosan with ethyleneglycol diglycidyl ether (EGDE); (2) absorption of a suitable amount of a solution of vinylpyrrolidone (VP) monomer from the porous CHT beads followed to VP polymerization and crosslinking inside the network. Sequential IPN's at different composition were obtained: they reversibly swell in water at various pH and show sensitive volumetric behaviour. 相似文献
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壳聚糖季铵盐及其衍生物的应用研究进展 总被引:1,自引:0,他引:1
壳聚糖是一种天然无毒多糖,可生物降解,具有生物相容性。在实际应用中壳聚糖水溶性差,只能在酸性介质中溶解。为了提高壳聚糖的溶解度并改善其理化及生物特性以扩大其应用范围,有必要对壳聚糖进行化学修饰。壳聚糖季铵盐是一种常见的壳聚糖修饰产物,属于水溶性壳聚糖衍生物,由于骨架上有强正电荷,因此其pH值溶解范围较宽。综述了壳聚糖季铵盐及其衍生物在抗菌活性、基因运载、给药系统、抗凝血材料、传感器等方面的应用进展,提出改进壳聚糖季铵盐及其衍生物的合成路线,可合成一系列生物学性能改良的壳聚糖季铵盐及其衍生物,有望将其应用于特殊领域。 相似文献
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In Young Kim Seon Jeong Kim Mi‐Seon Shin Young Moo Lee Dong‐Ic Shin Sun I. Kim 《应用聚合物科学杂志》2002,85(13):2661-2666
Graft copolymerization of epoxy‐terminated poly(dimethylsiloxane) (PDMS) onto chitosan was reacted without using a catalyst. pH‐sensitive hydrogels were obtained that are based on two different components: a natural polymer and a synthetic polymer. These PDMS substitutents provide the basis for hydrophobic interactions that contribute to the formation of hydrogels. Various graft hydrogels were prepared from different weight ratios of chitosan and PDMS. Swelling behavior of these hydrogels was studied by immersion of the gels in various buffer solution. Photocrosslinked hydrogels exhibited a high equilibrium water content (EWC). Particularly, the sample CP31 of the highest chitosan–PDMS weight ratio showed the highest EWC in time‐dependent, temperature‐dependent, and pH‐dependent swelling behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2661–2666, 2002 相似文献
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以化学共沉淀法合成Fe3O4纳米粒子为磁核,采用乳化交联法制备磁性壳聚糖微球,并对其形貌、结构和磁饱和强度等性质进行了表征。以磁性壳聚糖微球作为载体,固定化猪肺粗提物中的血管紧张素转化酶,并对固定化条件进行研究。结果表明,固定化血管紧张素转化酶的最佳条件为:pH值为8.3,最佳温度为50 ℃,最佳时间为1.5 h,最佳酶溶液蛋白浓度为6 mg/mL,此时固定化酶活力最高为0.048 U/g微球。与游离酶相比,固定化酶的pH值稳定性和热稳定性均得到提高。固定化酶重复使用10次,仍然保持40%以上相对活力,说明磁性壳聚糖微球是固定化血管紧张素转化酶的良好载体。 相似文献
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以巯基乙酸为稳定剂在水相中合成了CdTe量子点,并将合成的CdTe量子点进行表征、纯化。通过用0.05 mol.L-1PBS缓冲溶液调节不同的pH来考察量子点的荧光强度和pH的关系。研究发现,水溶性的CdTe量子点是pH敏感的,随着pH值的降低,量子点荧光强度的下降规律与溶液pH值呈现良好的线性关系。结果表明,CdTe量子点是一个令人满意的pH敏感的探针,有潜在的化学和生物传感能力。 相似文献
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In this paper, we report the interaction of chitosan with tetraethyl orthosilicate on the formation of silica nanoparticles under different conditions of pH (5–9) and chitosan concentration (0–0.001379 mM). The silica nanoparticles were characterized by means of N2-sorption, scanning electron microscopy and transmission electron microscopy. It was found that chitosan played two different roles on the formation of silica nanoparticles, depending on the pH values. At a low chitosan concentration, chitosan promoted the formation of larger silica nanoparticles in the pH range of 5–6, while it reduced the size of silica nanoparticles when the pH value was increased to the range of 6.5–8.5. However, based on the results of N2-sorption analysis, two different sizes of silica nanoparticles caused by the growth of silica at different phases were observed. At high chitosan concentration, the size of silica nanoparticles continuously increased in the pH range of 5–6, while only smaller size of silica nanoparticles was obtained in the pH range of 6.5–8.5. At pH 9, chitosan molecules were found to have no significant effect on the formation of silica nanoparticles even though a large amount of chitosan was employed. 相似文献
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《国际聚合物材料杂志》2012,61(12):628-636
The viscometric parameters of chitosan/poly(vinyl alcohol) mixtures determined at 37°C are sensitive to polymer composition and pH changes, giving information about interpolymer complexes formation. Hybrid composites based on interpolymeric chitosan/poly(vinyl alcohol) complexes and the inorganic matrix of layered double hydroxides were synthesized in the presence of glutaraldehyde. The viscoelastic parameters showed a stronger network formation at pH = 5.5 which is not broken down by the mechanical shear forces. The swelling kinetics of hybrid hydrogels is pH sensitive and the type of diffusion of small molecules into the network was established. 相似文献
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Nívia do Nascimento Marques Priscila Schroeder Curti Ana Maria da Silva Maia Rosangela de Carvalho Balaban 《应用聚合物科学杂志》2013,129(1):334-345
This study describes the stability and rheological behavior of suspensions of poly(N‐isopropylacrylamide) (PNIPAM), poly(N‐isopropylacrylamide)‐chitosan (PNIPAM‐CS), and poly(N‐isopropylacrylamide)‐chitosan‐poly(acrylic acid) (PNIPAM‐CS‐PAA) crosslinked particles sensitive to pH and temperature. These dual‐sensitive materials were simply obtained by one‐pot method, via free‐radical precipitation copolymerization with potassium persulfate, using N,N′‐methylenebisacrylamide as a crosslinking agent. Incorporation of the precursor materials into the chemical networks was confirmed by elementary analysis and infrared spectroscopy. The influence of external stimuli such as pH and temperature, or both, on particle behavior was investigated through rheological measurements, visual stability tests, and analytical centrifugation. The PNIPAM‐CS particles showed higher stability in acid and neutral media, whereas PNIPAM‐CS‐PAA particles were more stable in neutral and alkaline media, both below and above the lower critical solution temperature of PNIPAM (stability data). This is due to different interparticle interactions as well as those between the particles and the medium (also evidenced by rheological data), which were also influenced by the pH and temperature of the medium. Based on the results obtained, we found that the introduction of pH‐sensitive polymers to crosslinked PNIPAM particles not only produced dual‐sensitive materials but also allowed particle stability to be adjusted, making phase separation faster or slower, depending on the desired application. Thus, it is possible to adapt the material to different media. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献