【作者】 马贵平；

【导师】 聂俊；

【作者基本信息】 北京化工大学 ， 材料加工工程， 2009， 博士

【摘要】 甲壳素是自然界中储存量仅次于纤维素的第二大天然生物高分子,是一种环境友好型高分子。壳聚糖是由甲壳素脱乙酰氨基制备而得。壳聚糖不仅有生物相容性、生物可降解性、无毒等优点,还有抗癌性、止血性、抗菌性等优异性能。因此,壳聚糖在食品、化妆品、环保等工业上有较大的应用价值,尤其在生物医学领域可以作为烧伤敷料、术后粘连材料、药物载体和组织工程支架材料等。但由于壳聚糖的特殊结构,其不溶解于水和有机溶剂,只溶解于稀酸水溶液,极大地限制了其在生物医学的应用。为改进壳聚糖的溶解性能并拓宽其作为生物医用材料的应用范围,我们分别采用迈克尔加成反应和酰氯化反应制备了水性和油性壳聚糖衍生物,并利用改性的壳聚糖衍生物,采用静电纺丝方法和混合浇注法制备了可以用作皮肤烧伤敷料和人工软骨组织的生物医学材料。主要工作如下:1、在稀醋酸的水溶液中,对天然高分子壳聚糖和丙烯酰胺类单体采用迈克尔加成反应对其进行化学改性,考察了反应温度、反应时间和反应配比等实验因素对壳聚糖衍生物的取代度的影响,重点对壳聚糖和丙烯酸羟乙酯反应后壳聚糖衍生物的性质进行了研究,对壳聚糖衍生物的热稳定性性能、取代度、抗大肠杆菌性能以及溶菌酶降解能力作出初步评价。2、以改性水溶性壳聚糖衍生物(HEA-CS)为主体,和其他高分子聚乙烯醇(PVA)采用流延成膜法制备了可用作人工软骨组织的材料,对流延膜的结晶行为、热稳定性能、抗大肠杆菌和软骨组织细胞(SW1353)细胞毒性和细胞生长繁殖进行观察。抗大肠杆菌结果表明,流延膜具有一定的抗菌性能,SW1353细胞毒性测试(MTT)结果说明,以此为原料的流延膜无细胞毒性,其有利于细胞生长粘附、繁殖和生长,是人工软骨组织的良好替代品。3、在有机溶剂混合溶液中,实现了壳聚糖和长链酰氯的酰氯化反应,制备了有机溶解型(油性)壳聚糖衍生物。通过调节二者反应配比可以制备不同取代度的壳聚糖衍生物。采用红外光谱、氢核磁、XRD对其结构和形态进行分析,通过TG对其衍生物的热稳定性能进行分析,制备的衍生物可以溶解在丙酮、三氯甲烷等12种有机溶剂中,改性壳聚糖衍生物的结晶行为受侧链规整性的影响,其结晶行为与壳聚糖完全不同,热稳定性也较壳聚糖有所降低,拓展了壳聚糖衍生物的生物医学应用范围。4、以油溶性壳聚糖衍生物和聚羟基丁酸酯为原料,利用电纺丝技术,制备了纳米纤维无纺布。本部分考察了聚合物含量、纺丝电压和电导率对纺丝纤维的形成和形貌的影响。重点研究了该纺丝纤维材料的细胞毒性、细胞的贴附和生长繁殖状况等性质。研究结果表明,当油溶性壳聚糖衍生物/聚羟基丁酸酯质量之比小于70/30,能得到形貌均一且分布均匀的纤维。间接细胞毒性结果显示,油溶性壳聚糖衍生物和聚羟基丁酸酯电纺丝纤维膜对L929细胞没有毒性,有很好的生物相容性。细胞培养结果也显示,纺丝纤维膜能很好地促进细胞的贴附和生长繁殖。该纺丝纤维膜适合用作促进皮肤组织再生的伤口敷料。5、以油溶性壳聚糖衍生物和聚氧化乙烯为原料,利用电纺丝技术,制备了纳米纤维无纺布。本部分考察了聚合物浓度、纺丝电压和二者组分对纺丝纤维的形成和形貌的影响。此外,还重点研究了该纺丝纤维材料的水接触角,对其竹节和多孔结构的纤维采用相图方法进行了重点的分析和讨论。6、以壳聚糖、聚乙烯醇和聚乙烯吡咯烷酮三混合组分进行纺丝制备了纳米纤维,并以三氯甲烷溶液对纤维进行处理得到了表面粗糙的纳米纤维。本部分考察了混合溶液的聚乙烯醇含量、纺丝电压和聚乙烯吡咯烷酮含量对纺丝纤维的形貌和直径分布影响。这种多孔结构的纳米纤维有望在生物组织工程得到应用。更多还原

【Abstract】 Chitosan is an environmental friendly natural macromolecule and one of the most important and partially deacetylated derivatives obtained from chitin which is the second most abundant natural polysaccharide only next to cellulose in the world.Due to its biocompatibility, biodegradability,antibacterial and wound-healing activity and nontoxic property,chitosan is currently receiving a great deal of interest for biomedical and pharmaceutical application such as wound dressing,drug carrier and tissue engineered scaffolds and so on.However,chitosan is frequently limited by its insoluble nature in both water and current organic solvents because of its rigid crystalline structure and intra- and/or intermolecular hydrogen bonding which limited its application in the field of biomedical materials.In order to improve water and organic solubility for the further application of chitosan in biomedical materials fields,the water-soluble and organic-soluble chitosan derivatives were prepared by the Michael addition reaction and acylation reaction,respectively.Then,these derivatives were used to prepare biomedical application such as non-woven fabrics/nanofibers and tissue engineered scaffolds by electrospinning and blend solution-casting method techniques.The main contents and conclusions are described as follows.1.Water-soluble Hydroxyethylacryl-chitosan（HEA-CS） with different degrees of substitution from 0.18 to 1.2 was prepared by Michael addition reaction of chitosan and hydroxyethylacrylate. Hydroxyethylacryl-chitosan exhibited excellent solubility in distilled water.The thermal stability of hydroxyethylacryl-chitosan was lower than that of chitosan.Hydroxyethylacryl-chitosan showed strong lysozyme degradation and the degradation of hydroxyethylacryl-chitosan at the initial time depended on its molecular weight.The antimicrobial activity of hydroxyethylacryl-chitosan was low.This derivatiation procedure would be useful for the novel chemical modification to prepare water-soluble and biodegradable chitosan derivatives.2.The biocompatible blend films of HEA-CS/PVA were prepared by solution casting.The TS and the elongation increased with an increase content of PVA.The water contract angle of the blend film was low owing to the hydrophilic groups and the hydrophilic ability of the HEA-CS was higher than PVA.The surface morphologies of the freeze-dried blend films showed small pores and some interconnectivity. The blend film was thermally-stable owing to cross-linking with glutaraldehyde.The water swelling properties analysis indicated that HEA-CS in the blends promoted the water absorption owing to its porous structure.The antimicrobial ability of the blend films was decreased,but still had antimicrobial ability.Indirect cytotoxicity assessment of the blend films with human bone sarcoma cell（SW1353） indicated that the biomaterials were non-toxic and did not release substances harmful to living cells.3.The acylated chitosan with different degree of substitution from 1.8 to 3.8 were prepared by reaction of chitosan and stearoyl chloride in the mixed organic solutions.The acylated chitosan exhibited an excellent solubility in organic solvents at 25℃such as acetone,pyridine,benzene and dichloromethane.The thermal stability of acylated chitosan was lower than that of chitosan and the thermal stability of acylated chitosan decreased with increase of DS.The acylated chitosan had different crystallinity compared to that of chitosan for the long chain reside structure.This procedure could be a facile chemical modification method to prepare organic-soluble,and it could extent the application scope of chitosan.4.Biocompatible carboxyethyl organic soluble chitosan（O-CS）/ Polyhydroxybutyrate（PHB） fibers were successfully prepared by electrospinning.This part investigated the effects of polymer composition, electrospun voltage and electrospun distance on the fiber formation, morphology and the diameter distribution of blend fibers.Additionally, potential use of the electrospun fibers for wound dressing was studied by examining its cytotoxicity and cellular compatibility.The results showed that the fibers were hydrophobic.Indirect cytotoxicity assessment of the fiber mats indicated that the O-CS/PHB electrospun mat was nontoxic to L929 cell.Cell culture results showed that fibrous mats were well in promoting the cell attachment and proliferation.This novel electrospun matrix would be used as potential wound dressing for skin regeneration.5.Ultrafine and porous composite fibers were successfully fabricated by electrospinning of organic soluble chitosan（O-CS）/Poly ethylene oxide（PEO）.The WCA data demonstrated that the fibers membranes performed a quite hydrophobic character.The special morphology of neck and porous structure was observed experimentally during electrospinning.The neck and porous structure was got and decided by the competition between the phase separation and the fast evaporation rate of chloroform.6.Ultrafine electrospun fibers of Chitosan/Poly（vinylalcohol） /Poly（vinylpyrrolidone）（CS/PVA/PVP） were prepared via electrospinning. The effects of the concentration of PVA,PVP and the electrospinning voltage on the morphology of ultrafine fibers were investigated by SEM. The morphology and diameter distributions of ultrafine fibers were affected by the factors.The rough surface fibers could be obtained after etching with CHCl₃ and it could be used as Biology tissue engineering.更多还原