组织工程相关壳聚糖-明胶基生物材料

组织工程相关壳聚糖-明胶基生物材料;表面修饰剂;综述     

壳聚糖改性及其用于止血海绵的研究进展

壳聚糖具有抗菌、止血、无毒、促凝血、可降解以及良好的生物相容性等特点,现已被广泛应用于止血海绵的制备研究.本文针对单纯壳聚糖力学强度不足的缺点,综述了壳聚糖添加交联剂京尼平、醛类、单宁酸增强力学强度的研究进展;针对单纯壳聚糖不易溶于水的特点,综述了壳聚糖改性为羧甲基壳聚糖,壳聚糖季铵盐和烷基化壳聚糖增加或减少溶解度的研...     

贻贝启发功能改性的明胶基海绵止血材料的制备与性能

由战争、手术等而造成的大出血通常会导致更大的伤痛或更高的死亡率,因此,非常需要及时有效的止血以减少创伤导致死亡.而目前的止血材料都存在止血速度慢、止血效果差等问题.为提高材料的止血效率,本文受贻贝启发使用多巴胺和赖氨酸接枝改性的明胶(GDL)和氧化葡聚糖(ODE)为原料,通过冷冻干燥法制备多孔海绵状止血材料(GDL/O...     

壳聚糖水杨酸盐-明胶共混膜结构表征及其抗菌性

以溶液共混法成功制备出壳聚糖水杨酸盐－明胶共浊膜，用FT－IR、XRD、SEM表征了其结构，并测试了其吸水率，力学性能及抑菌性能。结果表明，壳聚糖水杨酸盐－胶胶共混膜中存在强烈的氢键相互作用及良好相容性，共混膜的力学性能随明胶含量增大而明显提高，当明胶含量为30％时，共混膜的抗张强度最大，其干、湿态抗张强度分别达99．9MPa和34．9MPa，比纯壳聚糖膜干，湿态抗张强度分别提高了99．8％有83．75，共浊膜抑菌性随明胶含量增加而下降，但其抑菌性仍明显高于壳聚糖膜。水杨酸的引入有利于改善其力学性能及抗菌性能，该共漫漫经膜作为一种潜在的伤口包扎材料，将具有广阔应用前景。     

壳聚糖-明胶共聚物的酶促合成及抑菌性质

壳聚糖;明胶;共聚物;微生物转谷氨酰胺酶;抗菌     

锌离子对壳聚糖复合膜结构和性能的影响

通过在壳聚糖溶液里加入乙酸锌制备Zn2+/壳聚糖复合膜,并利用FTIR、XRD、DSC、DMA和AFM考察了加入不同量Zn2+对壳聚糖复合膜微观结构、表面形貌、结晶性能以及热行为的影响.结果表明,壳聚糖分子中的—NH2、—OH、—NHCO—活性基团和Zn2+发生了配位反应,且随着Zn2+量的增加,有关复合膜表面的粗糙度明显增大.Zn2+的量增加到一定程度后会导致发生明显的相分离,复合膜的储能模量也随之明显下降.     

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。     

原位交联羧甲基壳聚糖/碳酸钙凝胶海绵的制备及其止血性能研究

以羧甲基壳聚糖(CMCS)、碳酸钙(CaCO₃)、葡萄糖酸内酯(GDL)和甘油(GLY)为原料,通过原位相转变制备水凝胶,经冷冻干燥工艺得到止血海绵,用于躯体非压迫性出血。通过扫描电镜、吸水率、孔隙率、溶血实验和全血凝固时间测试分别对海绵的理化性能、血液安全性、止血性能进行研究。当CaCO₃与CMCS的质量比为15%时,制得的海绵综合性能最好。该海绵呈疏松多孔片层状,止血时间较医用棉纱布材料缩短了35%,无血液毒性,是一种优良的止血海绵材料。     

巯基化壳聚糖/明胶的制备研究

仿生杂化构建可注射水凝胶支架是制备组织工程材料的一条有效途径,而天然聚合物的改性即成为其前提条件。本文以巯基乙酸和4-丁巯内酯为反应试剂采用均相反应法制备了巯基化天然聚合物衍生物。结果表明,利用壳聚糖和明胶上的氨基等活性基团,可采用不同途径对它们进行巯基化改性;在水溶性碳二亚胺的活化作用下巯基乙酸的羧基与壳聚糖的氨基形成酰胺键,从而将活性巯基引入到壳聚糖中,但大部分被氧化;随着贮存时间的延长,各改性物中的巯基含量逐渐降低,因此需将改性物保存于低温惰性环境中,以保持其反应活性。     

片状壳聚糖的脱乙酰化反应

本文采用一种新方法制备 10 0 %脱乙酰度的壳聚糖。低脱乙酰度壳聚糖溶解在酸溶液中并通过溶剂蒸发制备得到片状壳聚糖。片状壳聚糖进行一步碱处理就可以得到高脱乙酰度壳聚糖。     

Catalytic Acetylation of Alcohols and Phenols with Potassium Dodecatungstocobaltate Trihydrate

Summary.  Alcohols and phenols are converted to esters in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of potassium dodecatungstocobaltate trihydrate (K₅CoW₁₂O₄₀ · 3H₂O). Received August 27, 2001. Accepted (revised) October 29, 2001     

Simple and Efficient Method for Acetylation of Alcohols,Phenols, Amines,and Thiols Using Anhydrous NiCl2 Under Solvent-Free Conditions

Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac₂O) in the presence of 0.1 mol% (13 mg) anhydrous NiCl₂, an inexpensive and easily available catalyst. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.     

Simple and Efficient Method for Acetylation of Alcohols,Phenols, Amines,and Thiols Using Anhydrous NiCl2 Under Solvent-Free Conditions

Solvent-free acetylation of alcohols, phenols, amines, and thiols with acetic anhydride (Ac₂O) in the presence of 0.1 mol% (13 mg) anhydrous NiCl₂, an inexpensive and easily available catalyst, is described. Excellent yields, short reaction time, and mild reaction conditions are important features of this method.     

丁烯酮-丙烯腈共聚物与过渡金属的配合物催化甲醇羰基化制乙酸和乙酸酐

合成了一系列丁烯酮-丙烯腈共聚物与过渡金属的配位化合物,用X-射线光电子能谱(XPS)研究了其中存在的配位特征。通过甲醇羰基化反应制备乙酸、乙酸酐的反应,考察了不同催化剂的活性。实验结果表明,在反应中其活性顺序:铑配合物>镍配合物>钌配合物>钴配合物。     

三（2—吡啶甲基）甲烷为配体的双金属配合物的制备及其催化性能研究

报道了一种新的以三（２－吡啶甲基）甲烷为配体，以铑为主催化活性中心，并辅以其它金属为辅助催化的双金属配合物该配合物在相对温和的条件下，可迅速催化甲醇羰基化为醋酸，及醋酸甲酯羰基化为醋酐。实验结果证明，第二种金属的引入提高了配合物的催化活性，这种催化活性的提高因第二种金属的不同而有所差异。另外，根据配体的结构阐述了其对羰基化反应的作用机理。     

丙二酸锂-铑配合物的结构及催化性能研究

本文采用丙二酸锂为配体，与四羰基二氯二铑形成双齿配位的顺二羰基铑配合物，研究表明，在催化甲醇羰基化制乙酸的反应中，该配合物显示出高的活性和选择性。     

Al(HSO4)3 as an Efficient Catalyst for the Acetylation of Alcohols in Solution and Under Solvent Free Conditions

Summary. Alcohols are acetylated in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of Al(HSO₄)₃ in solution and under solvent free conditions. All reactions were performed at room temperature in good to high yields.     

A small-angle neutron scattering and rheology study of the composite of chitosan and gelatin

The composite chitosan/gelatin solutions and films formed from these solutions were studied by rheological measurements, SANS and tensile tests. The relationship between the inter-molecule interactions with microstructure, rheological behaviour of a solution and eventually the mechanical performance of formed films was established. It was found that the complex formed between chitosan and gelatin was mainly through hydrogen bond but the size of the structure was also affected by electrostatic repulsions. The local structure (correlation length) and the global structure (large inhomogeneous structure size) in the composite solutions were found to be highly correlated to each other. It was also found that the interactions between these two polymers in solution were closely related to the mechanical properties of the formed films. This work will enable one to design films with desired mechanical properties through the combination of different polymers at optimum weight ratios.     

A Novel Application of Ammonium Formate/Palladium on Carbon for Selective Reduction of the Heterocyclic Ring in Quinolines and Isoquinolines

Ammonium formate/palladium on carbon was found to be a convenient system for selective reduction, in good yields, of the heterocyclic ring in quinoline and isoquinoline derivatives.     

Facile synthesis of simple mono-alkyl phosphates from phosphoric acid and alcohols

Simple aliphatic alcohols can be selectively converted into mono-alkyl phosphate esters at the laboratory scale using the acetic anhydride-mediated activation of inorganic phosphate.