N-辛基-O-聚乙二醇两亲性壳聚糖的制备与表征

以自然界富有的天然壳聚糖为原料,在其分子结构的2位-NH2上引入部分疏水性辛基,并对其余的-NH2 进行有效保护;然后在3,6位的-OH上引入亲水性聚乙二醇基团,合成了具有两亲性的N-辛基-O-聚乙二醇壳聚糖衍生物。通过FTIR,1HNMR和元素分析对其分子结构和N-位、O-位取代度进行了表征。该壳聚糖衍生物具有两亲性,水溶性好,分子结构中保留有可用于后续交联反应的活性-NH2,在制备两亲型壳聚糖微球型药物载体领域具有潜在的应用价值。     

季铵化两亲性壳聚糖衍生物载药性质研究

合成新型季铵化两亲性壳聚糖衍生物(DEAE-CMC)。用乳化交联固化法制备DEAE-CMC/VB12载药微球。用激光粒径仪、扫描电镜对微球的大小和形态进行表征。载药微球的平均粒径为4.53μm。在pH=7.4磷酸盐缓冲溶液中,DEAE-CMC/VB12载药微球体外药物释放达到平衡时间为60 h,药物包封率为33.70%,载药量为12.47%,平衡时药物累积释放率为56.30%。     

壳聚糖缓释微球的制备与表征

以壳聚糖(Chitosan)、戊二醛(Glutaraldehyde)、尿素(Urea)为主要原料,采用乳化-化学交联法制备尿素-壳聚糖缓释微球.通过红外光谱测试,分析缓释微球的结构特征;通过扫描电镜测试,观察微球的微观形貌;通过交联度测试确定戊二醛的最佳用量;通过缓释测试,测定壳聚糖微球的缓释效果.结果表明:采用乳化-...     

季铵化壳聚糖衍生物的合成与表征

以壳聚糖为原料,首先进行壳聚糖的季铵化,随后连接长链饱和脂肪酸,选择癸酸、月桂酸、肉豆蔻酸、棕榈酸和硬脂酸来连接季铵化壳聚糖,使其具有两亲性以成为药物传送的载体。设计并合成了两亲性的季铵化壳聚糖衍生物,并使用红外光谱、核磁共振氢谱和核磁共振碳谱等方法对其化学结构进行表征。实验发现,季铵化程度对脂肪酸连接反应影响较大,分别选择了一步和两步季铵化的壳聚糖与脂肪酸进行反应,以探讨其中的关系。     

改性壳聚糖加碘膜的制备与表征

壳聚糖(CTS)和水杨醛、环氧氯丙烷交联制备壳聚糖衍生物(RS-CTS-E),并制备相应衍生物的凝胶膜,将凝胶膜浸没在一定浓度碘乙醇溶液中,制备改性壳聚糖加碘膜(RS-CTS-E-I2),并对其进行了IR、SEM等表征。碘含量分析表明:改性壳聚糖凝胶膜对单质碘吸附量随碘乙醇溶液浓度增加而增大。碘吸附动力学结果表明其平衡吸附时间为6 h。抑菌性测试结果表明,w(I2)=19.05%时RS-CTS-E-I2膜对金黄色葡萄球菌抑菌环和大肠杆菌抑菌环的抑菌环直径分别为(31±1)mm和(30±1)mm,均为高度敏感。     

壳聚糖止血微球的制备优化及表征

以壳聚糖为原料,采用乳化交联技术制备壳聚糖止血微球。在单因素实验结果的基础上,采用响应面法优化壳聚糖止血微球的制备条件,通过体外凝血法对其止血活性进行评价。结果表明,最优制备工艺条件为:壳聚糖浓度1.4%,壳聚糖分子量600 k Da和戊二醛与壳聚糖质量比1∶1。在此条件下,微球平均溶胀率为346.56%,与理论预测相当吻合;止血微球具有良好的外观形貌,分散性好;红外分析表明,壳聚糖止血微球已经成功地进行了化学交联,具有稳定的空间结构;壳聚糖微球具有显著的促凝血活性,呈现剂量相关性。将为开发新型壳聚糖高效止血材料奠定基础。     

TiO2/N-琥珀酰壳聚糖复合材料的制备及表征

以N-琥珀酰壳聚糖与TiO2复合制备了TiO2/N-琥珀酰壳聚糖复合材料。采用透射电镜(TEM)、傅里叶红外光谱(FTIR)、紫外-可见光谱(UV-Vis)、X射线衍射(XRD)、粒径及Zeta电位分析对复合材料进行表征。结果表明,TiO2表面羟基与N-琥珀酰壳聚糖分子中的羟基、酰胺、羧基相互作用形成了稳定的复合材料;复合材料中TiO2晶型呈锐钛矿型;复合材料平均粒径为50nm,Zeta电位达39mV;紫外-可见光谱显示,复合材料的光响应范围拓宽到可见光区,且对光的吸收能力显著增强,但在模拟太阳光下其光催化效率较TiO2有所下降。     

壳聚糖止血微球的制备优化及表征

以壳聚糖为原料,采用乳化交联技术制备壳聚糖止血微球。在单因素实验结果的基础上,采用响应面法优化壳聚糖止血微球的制备条件,通过体外凝血法对其止血活性进行评价。结果表明,最优制备工艺条件为:壳聚糖浓度1.4%,壳聚糖分子量600 k Da和戊二醛与壳聚糖质量比1∶1。在此条件下,微球平均溶胀率为346.56%,与理论预测相当吻合;止血微球具有良好的外观形貌,分散性好;红外分析表明,壳聚糖止血微球已经成功地进行了化学交联,具有稳定的空间结构;壳聚糖微球具有显著的促凝血活性,呈现剂量相关性。将为开发新型壳聚糖高效止血材料奠定基础。     

壳聚糖微球的制备

用甲醛作为交联剂,通过悬浮交联法制备粒径不同的壳聚糖微球。通过控制反应条件,可以得到单分散性的微米级微球。通过光学显微镜及红外光谱仪等仪器对所得的产物进行了表征。     

壳聚糖微球的制备研究

利用液体石蜡作有机分散介质,甲醛、戊二醛作交联剂,通过反相悬液交联法制备了微米级窄分布壳聚糖微球,对合成最佳条件进行了实验选择,并对产物的形态、红外光谱特性及吸附行为进行了初步表征     

壳聚糖/聚丙烯酸共聚物微球的制备及性能

以环己烷为油相,壳聚糖溶液为水相,运用反相乳液聚合法制得了具有pH敏感性的壳聚糖/聚丙烯酸共聚物微球。讨论了微球在pH=1～10缓冲溶液中的溶胀率变化,研究表明,微球在强酸性(pH≈1)和碱性(pH>7)条件下,溶胀率均在10倍以上;而在pH=2～6时溶胀较差,当pH=4时出现最低值,溶胀率低于1倍。光学显微镜所观察到的微球粒径均在40μm以内,且大小均匀。采用傅里叶红外光谱仪分析了不同配比样品特征峰的峰值和峰面积的变化。用722光栅分光光度计研究了共聚物微球包埋考马斯亮蓝的溶胀释放过程。     

Synthesis,Characterization and Optimization of Water-Soluble Chitosan Derivatives

Chitosan was chemically modified using monochloroacetic acid at various reaction conditions. Chemical structure was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The carboxymethyl chitosan (CM-chitosan) was prepared at different temperatures, water/isopropanol (IPA) ratios and alkali concentrations. Reaction conditions have great influence on the degree of substitution (DS) and, in turn, the solubility. The water solubility of chitosan derivatives depended upon modification conditions and degree of substitution.     

Factors Influencing the Antibacterial Activity of Chitosan and Chitosan Modified by Functionalization

The biomedical and therapeutic importance of chitosan and chitosan derivatives is the subject of interdisciplinary research. In this analysis, we intended to consolidate some of the recent discoveries regarding the potential of chitosan and its derivatives to be used for biomedical and other purposes. Why chitosan? Because chitosan is a natural biopolymer that can be obtained from one of the most abundant polysaccharides in nature, which is chitin. Compared to other biopolymers, chitosan presents some advantages, such as accessibility, biocompatibility, biodegradability, and no toxicity, expressing significant antibacterial potential. In addition, through chemical processes, a high number of chitosan derivatives can be obtained with many possibilities for use. The presence of several types of functional groups in the structure of the polymer and the fact that it has cationic properties are determinant for the increased reactive properties of chitosan. We analyzed the intrinsic properties of chitosan in relation to its source: the molecular mass, the degree of deacetylation, and polymerization. We also studied the most important extrinsic factors responsible for different properties of chitosan, such as the type of bacteria on which chitosan is active. In addition, some chitosan derivatives obtained by functionalization and some complexes formed by chitosan with various metallic ions were studied. The present research can be extended in order to analyze many other factors than those mentioned. Further in this paper were discussed the most important factors that influence the antibacterial effect of chitosan and its derivatives. The aim was to demonstrate that the bactericidal effect of chitosan depends on a number of very complex factors, their knowledge being essential to explain the role of each of them for the bactericidal activity of this biopolymer.     

Chitosan microspheres and sponges: Preparation and characterization

In this study, chitosan microspheres and sponges were prepared and characterized for diverse biomedical applications successfully. The chitosan microspheres were obtained with a “suspension crosslinking technique” in the size range of 30–700 μm. The stirring rate of the suspension medium and the chitosan/acetic acid ratio, emulsifier, and crosslinker, that is, the glutaraldehyde concentration in the suspension medium, were evaluated as the effective parameters on the size/size distributions of the microspheres. The microsphere size/size distributions were increased with the decreasing of all effective parameters except the chitosan/acetic acid ratio. In the second part of the study, chitosan sponges were prepared with a solvent‐evaporation technique and sponges were cross‐linked either during the formation or after the formation of sponges by using a cross‐linker, that is, glutaraldehyde. When the sponges were crosslinked during the formation, fibrillar structures were obtained, while the leaflet structures were obtained in the case of crosslinking after the formation of sponges. In the last part of the study, the swelling behavior of both the chitosan microspheres and sponges were evaluated using different amounts of the crosslinker. The swelling ratio was increased in both types of structures, that is, microspheres and sponges, by decreasing the amount of the crosslinker. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1637–1643, 2000     

壳聚糖复合微球的制备及其对F-的吸附

以活性炭、氧化铝和硫酸铝为包合物制备了壳聚糖复合微球。通过对吸附时间、温度、包合物吸附剂等相关因素,考察了壳聚糖复合微球对含氟水的处理效果,结果表明Al2(SO4)3-活性炭-壳聚糖复合微球除氟的效果最佳。该复合微球在29．0℃处理8min后,对F^-的吸附率高达99．28％,用稀碱液淋洗可实现对复合微球的再生,脱洗率达93．69％。     

Preparation of Novel Poly(hydroxyethyl methacrylate-coglycidyl methacrylate)-Grafted Core-Shell Magnetic Chitosan Microspheres and Immobilization of Lactase

Poly(hydroxyethyl methacrylate-co-glycidyl methacrylate)-grafted magnetic chitosan microspheres (HG-MCM) were prepared using reversed-phase suspension polymerization method. The HG-MCM presented a core-shell structure and regular spherical shape with poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) grafted onto the chitosan layer coating the Fe₃O₄ cores. The average diameter of the magnetic microspheres was 10.67 μm, within a narrow size distribution of 6.6–17.4 μm. The saturation magnetization and retentivity of the magnetic microspheres were 7.0033 emu/g and 0.6273 emu/g, respectively. The application of HG-MCM in immobilization of lactase showed that the immobilized enzyme presented higher storage, pH and thermal stability compared to the free enzyme. This indicates that HG-MCM have potential applications in bio-macromolecule immobilization.     

环氧衍生物开环法制备壳聚糖季铵盐

采用异丙醇为溶剂,以壳聚糖(CTS)、2,3-环氧丙基三甲基氯化铵(GTA)为原料,用环氧衍生物开环法制备了壳聚糖季铵盐(HACC),通过单因素实验,考察了反应物摩尔比、反应时间、反应温度等因素对产物取代度的影响,结果表明,制备壳聚糖季铵盐的最优工艺条件为:n(CTS):n(GTA)=1∶4,壳聚糖相对分子质量(简称分子量,下同)3.2×105,碱化时间14h,预处理壳聚糖含水率20％,反应pH =7,反应温度75℃,反应时间8h.通过红外光谱、扫描电镜、热重分析对壳聚糖、壳聚糖季铵盐的结构、外观形貌、热稳定性进行了表征与分析,结果表明,壳聚糖季铵化改性以N取代为主,改性后外貌和粒度有了明显变化,并且热稳定性降低.