胆固醇接枝壳聚糖及其性能

以胆固醇琥珀酸单酯对壳聚糖进行仿生功能化改性, 并利用红外光谱和核磁共振波谱对改性后产物进行了表征. 通过接触角测试、 仿生矿化及细胞培养等方法研究了改性后产物的相关性能. 结果表明, 改性后的壳聚糖衍生物接触角有所增大. 在仿生矿化过程中, 随着时间的延长, 壳聚糖衍生物具有对沉积的钙磷盐的稳固作用. 在细胞培养过程中, 改性后的壳聚糖膜上细胞增殖明显. 噻唑蓝(MTT)比色法、 扫描电子显微镜(SEM)与激光共聚焦显微镜(CLSM)表征结果表明, 改性后的壳聚糖膜具有促进3T3细胞黏附、 伸展与增殖的效果.     

疏水性聚丙烯酸酯人工晶状体的低温等离子体改性

通过低温等离子体表面改性技术对疏水性聚丙烯酸酯人工晶状体进行表面改性, 并对改性前后材料的表面结构、形貌和光学性能进行了表征. 静态水接触角结果显示, 经过氨等离子体处理后的人工晶状体亲水性效果最好, 同时最佳的改性时间为120 s, 改性功率为150 W. XPS分析结果进一步证实, 经等离子体处理后, 在人工晶状体表面引入了极性基团. 原子显微镜观察结果显示, 改性后材料表面更加凹凸不平, 粗糙度显著增加而透光率变化很小, 但过大功率改性的样品透光率明显下降. 时效性测试结果表明, 人工晶状体在改性14 d后疏水性恢复趋于稳定.     

仿细胞外层膜结构修饰交联壳聚糖的研究

采用溶液自由基聚合,合成甲基丙烯酰氧乙基磷酰胆碱(MPC)-甲基丙烯酰氧丙基三甲氧基硅(TSMA)二元共聚物(PMT82),将其涂覆在戊二醛交联壳聚糖(CS-GA)表面,通过三乙胺蒸汽催化处理获得具有仿细胞外层膜结构(CS-GA-PMT82b)的表面.用动态接触角(DCA)、X-射线光电子能谱(XPS)对改性后交联壳聚糖表面的亲疏水性、元素组成等进行表征,并通过血小板黏附实验对其抗凝血性进行评价.研究结果表明,这种利用涂覆催化交联的方式将含有三甲氧基硅可交联基团的磷酰胆碱聚合物交联固定在壳聚糖表面,获得了较为稳定的仿细胞外层膜结构的CS-GA-PMT82b涂层表面.与壳聚糖相比,改性后壳聚糖的血小板黏附显著减少,抗凝血性能显著提高.这种改善材料的方式有望成为生物医用材料表面改性领域的有效的新手段.     

采用层层自组装与光化学修饰法在聚氨酯表面固定生物多糖衍生物

采用层层自组装技术与光化学修饰方法相结合在聚氨酯材料表面固定生物多糖衍生物,首先合成具有光反应活性的叠氮壳聚糖,再在聚氨酯基材表面进行叠氮壳聚糖与香菇多糖硫酸酯的层层自组装,然后通过光化学反应对自组装多层膜修饰层进行交联,制备得到生物多糖衍生物层层自组装与光化学表面修饰的聚氨酯材料.通过红外光谱、X射线光电子能谱、水接触角测量仪、抗菌活性测试、溶血试验和血小板黏附测试等方法对被修饰聚氨酯材料的表面性能和生物性能进行了分析,测试结果表明修饰后的聚氨酯材料表面的亲水性和血液相容性得到改善,并且被修饰材料对大肠杆菌具有良好的抑制效果.     

羊毛表面改性对拒水拒油整理的作用及机理研究

应用扫描电镜(SEM)、X射线光电子能谱(XPS)和衰减全反射红外光谱(FTIR-ATR)等现代表面分析技术研究不同改性处理羊毛表面的化学和物理结构特性.SEM研究结果表明,经低温等离子体表面改性或特定化学改性后的羊毛鳞片表面呈现纳米尺度的沟槽和凹凸结构,应用Wenzel公式和Cassie and Baxter公式阐述了表面粗糙度与接触角的关系,揭示了羊毛表面改性对于提高拒水拒油整理效果的原因所在.XPS和FTIR-ATR研究表明,上述物理和化学的表面改性技术使羊毛表面的二硫键氧化断裂和表面类脂物质改性/除去,促进拒水拒油整理剂的吸附和固着.表面改性和拒水拒油整理的协同效应赋予羊毛类荷叶效应,使其呈现超级拒水拒油拒污功能.     

骨髓基质干细胞在等离子体处理PEGDA基凝胶表面的黏附和增殖

通过低温等离子体技术对聚乙二醇双丙烯酸酯(PEGDA)/甲基丙烯酸β-羟乙酯(HEMA)共聚物水凝胶生物材料进行表面改性,以骨髓基质干细胞(BMSc)为细胞模型,考察了细胞在等离子体表面改性前后的水凝胶材料的黏附和增值行为,材料的表面性能通过 X 射线光电子能谱、接触角和扫描电镜进行表征.研究结果表明,材料表面经氩等离...     

聚二甲基硅氧烷表面亲水性的研究

为了使聚二甲基硅氧烷(PDMS)具有较稳定的亲水性表面,利用氧等离子体技术对PDMS表面进行处理。研究了氧等离子体处理PDMS表面的时间、功率、氧气流量等参数对表面亲水性的影响,通过接触角测量和X-射线光电子能谱(XPS)对处理效果进行了评价。实验表明:PDMS经氧等离子体处理后放置700 h的表面接触角为72°,达到了持久改性的目的;XPS分析表明,表面亲水性的改善主要是由于表面极性成分的增加,最后讨论了氧等离子体处理PDMS表面的改性机理。     

聚酯薄膜表面接枝含硅氧烷共聚物及微生物黏附性研究

通过表面引发原子转移自由基聚合(SI-ATRP)在聚对苯二甲酸乙二醇酯(PET)薄膜表面接枝聚苯乙烯-聚二甲基硅氧烷嵌段共聚物(PET-g-PS-b-PDMS),制备具有强疏水性表面的聚酯薄膜.利用X-射线光电子能谱仪(XPS),傅里叶变换红外光谱仪(FTIR/ATR),场发射扫描电镜(FESEM)对改性前后聚酯薄膜的表面组成、结构和形貌进行分析与表征;利用接触角测试仪和微生物黏附实验对比研究接枝改性前后PET薄膜的润湿性和对微生物黏附性的影响.结果表明,随反应时间延长,聚酯薄膜表面接枝量增加,水接触角增大.当接枝聚合反应时间为12 h,接枝密度可达0.72 mg/cm2,接触角达到126°,薄膜表面细菌黏附量也随之降到最低.     

N-羧丙酰壳聚糖钠增强改性壳聚糖棒材

采用原位沉析法制备N-羧丙酰壳聚糖钠增强改性的三维壳聚糖复合棒材, 并用傅里叶变换红外(FTIR)光谱、X射线衍射(XRD)、热重(TG)分析、扫描电镜(SEM)以及力学性能测试等方法研究复合棒材结构与性能之间的关系. FTIR分析表明, 壳聚糖分子中的氨基官能团和乙酰氨基官能团均与N-羧丙酰壳聚糖钠分子中的羧酸盐官能团发生强烈的静电相互作用. 加入N-羧丙酰壳聚糖钠后: 两种分子间产生强烈的静电相互作用, 限制了大分子链的运动, 使得大分子链趋于刚性, 同时复合棒材的层状叠加结构变得更加紧密, 提高了复合棒材的热稳定性与力学性能; 大分子链的刚性增强, 限制了分子链排入晶格, 从而降低了壳聚糖的结晶度. 当复合棒材中含有15% (w)的N-羧丙酰壳聚糖钠时, 其弯曲强度和弯曲模量可达156.0 MPa、5.3 GPa, 与纯壳聚糖棒材相比, 分别提高了68.8%、29.3%.因此, N-羧丙酰壳聚糖钠可有效地增强改性三维壳聚糖棒材, 该三维复合物棒材有望用作骨折内固定材料.     

水解可控功能切换型聚合刷的构筑及表面性能

采用表面受限光接枝技术在玻璃表面构筑末端酯键可水解的羧酸甜菜碱酯阳离子聚合物刷(PCBMA-1C2),通过调节氨水浓度控制羧酸甜菜碱酯末端酯键的水解程度,实现表面聚合物刷中季铵阳离子和羧酸甜菜碱两性离子基团分配比例的改变.通过X射线光电子能谱(XPS)和接触角测试表征了改性表面的化学结构和亲/疏水性能,通过蛋白质吸附和血小板黏附实验研究了玻璃表面改性前后及水解前后电荷性质对生物分子相互作用的影响.结果发现,当氨水浓度为0.1,0.2,0.3和0.4 mol/L时,聚合物刷PCBMA-1C2改性表面羧酸甜菜碱酯末端酯键的水解率分别为6%,43%,56%和~100%,随着水解程度的增大,改性表面牛血清白蛋白(BSA)的吸附量依次降低了3%,76%,93%,96%,纤维蛋白原(Fg)吸附量则依次降低了11%,45%,90%和96%;当水解率50%时,改性表面表现出优异的抗蛋白质吸附和血小板黏附性能.     

乙酰化对壳聚糖-明胶海绵结构和性能的影响

用乙酸酐对壳聚糖与明胶共混物进行乙酰化,然后冷冻干燥制备乙酰化壳聚糖-明胶海绵,并研究乙酰化对海绵结构与性能的影响。用盐酸环丙沙星作模型药物,探讨载药海绵的抑菌效果。结果表明:制得的海绵具有多孔结构,随壳聚糖在混合物中含量的增加,海绵的吸水率和保水率先增后减;随着乙酰化程度的提高,海绵的吸水率先减后增,而保水率与吸水率的变化规律相反。酶对海绵的降解率不受壳聚糖和明胶混合比例的影响,但随海绵乙酰化程度的增加而增加。载药海绵的抑菌效果与海绵中壳聚糖含量有关。     

Acetylation and molecular mass effects on barrier and mechanical properties of shortfin squid chitosan membranes

Chitosan samples with different N-deacetylation levels were obtained from β-chitin under heterogeneous alkali conditions. Oxidative depolymerisation was performed to attain low-acetylated chitosan samples with different molecular mass. Water vapour permeability, membrane swelling and tensile mechanical properties were analysed in plasticized self-supporting chitosan membranes. The main purpose was to describe unambigously the effect of the biopolymer molecular mass and acetylation degree on these properties. Commercially available chitosan samples derived from α-chitin were also studied for comparison. The equilibrium degree of swelling in water and the water vapour permeability increase by increasing the molecular mass or the degree of acetylation. Regarding the effect on the mechanical properties, generally harder and tougher membranes were obtained for chitosans with higher molecular mass or lower acetylation degree. These observations are tentatively explained based on the different structural characteristics of the polymer and can lead to a better understanding of the tools necessary to tailor a specific type of chitosan membrane.     

Preparation and properties of polyvinyl acetal sponge modified by chitosan

The polyvinyl acetal sponge modified by chitosan was prepared by adding chitosan/polyvinyl alcohol (PVA) solution during the acetalation reaction of PVA and formaldehyde. The effect of vesicant and chitosan to the pore morphology, water absorption ratio, water absorption rate, expansion time and mechanical properties were studied. The polyvinyl acetal sponge modified by chitosan was used as a hemostatic packing material for the injured rabbit nasal tissue. The hemostatic effect and the healing effect of the modified sponge on the nasal mucosa after nasal surgery were studied. The results indicated that the polyvinyl acetal sponge modified by chitosan has an interconnected pore structure and the wall between large pores also has small pores. The chitosan adhered on the inner surface of the pores. The increased content of vesicant led to an increase in pore diameter, in the water absorption ratio and in expansion time. However, there was only a small change in the water absorption rate and a decrease in tensile strength and compression strength were noted. With an increase in chitosan content, the pore diameter and interconnection of the sponge was reduced. Water absorption ratio, expansion time and water absorption rate decreased, but tensile strength and compression strength improved. Observation of the rabbit nasal tissue after surgical operation suggested that polyvinyl acetal sponge modified by chitosan has an anti-inflammatory, hemostatic and anti-adherent characteristic and could promote the healing and functional recovery of rabbit nasal mucosa. __________ Translated from Journal of Jinan University (Natural Science & Medicine Edition), 2007, 28(3): 283–287 [译自: 暨南大学学报(自然科学与医学版)]     

Gamma Radiation‐Induced Crosslinked PVA/Chitosan Blends for Wound Dressing

Crosslinked polyvinyl alcohol (PVA) and chitosan polymer blends have been prepared by using gamma irradiation. Chitosan was used in the blends to prevent microbiological growth, such as bacteria and fungi on the polymer. The physical properties of the blend, such as gelation, water absorption, and mechanical properties were examined to evaluate the possibility of its application for wound dressing. A mixture of PVA/chitosan, with different ratios, were exposed to gamma irradiation doses of 20, 30, 50 KGy, to evaluate the effect of irradiation dose on the physical properties of the blend. It was found that the gel fraction increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased as the composition of chitosan increased in the blend. The PVA/chitosan blend has a water content in the range between 40% and 60% and water absorption between 60% and 100%. The water vapor transmission rate value (WVRT) of the PVA/chitosan blend varies between 50% and 70%. The examination of the microbe penetration shows that the prepared blend can be considered as a good barrier against microbes. Thus, the PVA/chitosan blend showed satisfactory properties for use as a wound dressing.     

Morphology and characterization of 3D micro-porous structured chitosan scaffolds for tissue engineering

This research studies the morphology and characterization of three-dimensional (3D) micro-porous structures produced from biodegradable chitosan for use as scaffolds for cells culture. The chitosan 3D micro-porous structures were produced by a simple liquid hardening method, which includes the processes of foaming by mechanical stirring without any chemical foaming agent added, and hardening by NaOH cross linking. The pore size and porosity were controlled with mechanical stirring strength. This study includes the morphology of chitosan scaffolds, the characterization of mechanical properties, water absorption properties and in vitro enzymatic degradation of the 3D micro-porous structures. The results show that chitosan 3D micro-porous structures were successfully produced. Better formation samples were obtained when chitosan concentration is at 1–3%, and concentration of NaOH is at 5%. Faster stirring rate would produce samples of smaller pore diameter, but when rotation speed reaches 4000 rpm and higher the changes in pore size is minimal. Water absorption would reduce along with the decrease of chitosan scaffolds’ pore diameter. From stress–strain analysis, chitosan scaffolds’ mechanical properties are improved when it has smaller pore diameter. From in vitro enzymatic degradation results, it shows that the disintegration rate of chitosan scaffolds would increase along with the processing time increase, but approaching equilibrium when the disintegration rate reaches about 20%.     

Mechanically Adaptive and Shape‐Memory Behaviour of Chitosan‐Modified Cellulose Whisker/Elastomer Composites in Different pH Environments

Biomimetic polymer composites with water‐active mechanically adaptive and shape‐memory behaviour in different pH environments are synthesised by using chitosan‐modified cellulose whiskers (CS‐CWs) as the stimulus‐responsive phase and thermoplastic polyurethane (TPU) as the resilient matrix. The effect of surface modification on the mechanically adaptive behaviour of CS‐CW/TPU composites is investigated by using three representative solutions with various pH values. The results show that surface modification significantly enhances the modulus contrast under wet and dry conditions with the acidic solution as the stimulus, while maintaining the high modulus contrast with the basic solution as the stimulus. CS‐CW/TPU composites also exhibit excellent shape‐memory effects in all three solutions that are comparable to those pristine CW/TPU composites. Furthermore, activation of force generation in the stretched CS‐CW/TPU composites by water absorption/desorption was observed.     

Vacuum ultraviolet optical analysis of spin‐cast chitosan films modified by succinic anhydride and glycidyl phenyl ether

Optical properties of spin‐cast chitosan films were determined in the vacuum ultraviolet (VUV) through visible regions of the spectrum using spectroscopic ellipsometry. The onset of absorption in the ultraviolet was determined for chitosan films modified with succinic anhydride (SA) and glycidyl phenyl ether (GPE). This absorption was accounted for by including Gaussian and Tauc–Lorentz shaped oscillators in the optical model. VUV through visible optical constants were determined for these modified films, as well as for immunoglobulin G (IgG) attached to GPE‐modified samples. Several resonant oscillator structures exhibit greatly differing oscillator parameters for the as‐deposited, as well as SA‐ and GPE‐modified films. These in‐plane and out‐of‐plane oscillator strengths, energy positions, and broadening were determined and tabulated, and their chemical origins identified. A phenyl resonant π‐bond at approximately 6.3 eV was observed for the GPE‐modified sample. This was not present in the bare chitosan data. GPE contains a phenyl group in the molecule and absorption due to it is clearly identified. Clarity of data after surface chemical modification is due to the high surface sensitivity of VUV ellipsometry. Copyright © 2007 John Wiley & Sons, Ltd.     

The influence of chitosan on in vitro properties of Eudragit RS microspheres

Eudragit RS microspheres containing chitosan hydrochloride were prepared by the solvent evaporation method using acetone/liquid paraffin solvent system and their properties were compared with Eudragit RS microspheres without chitosan, prepared in our previous study. Different stirring rates were applied (400-1200 rpm) and drug content, Higuchi dissolution rate constant, surface and structure characteristics of the microspheres were determined for each size fraction. An increase in average particle size with a reduction of stirring rate appeared in limited interval in both series. The average particle size of microspheres without chitosan, prepared at the same stirring rate, was smaller. Pipemidic acid content increased with increasing fraction particle size, but not with increasing stirring rate as it was observed for microspheres without chitosan. We presume that high pipemidic acid content in larger microspheres is a consequence of cumulation of undissolved pipemidic acid particles in larger droplets during microspheres preparation procedure. Pipemidic acid release was faster from microspheres with chitosan and no correlation between Higuchi dissolution rate constant and stirring rate or fraction particle size was found, though it existed in the system without chitosan. Structure and surface characteristics of microspheres observed by scanning electron microscope (SEM) were not changed significantly by incorporation of chitosan. But in contrast with microspheres without chitosan, the surface of chitosan microspheres was more porous after three hours of dissolution. It is supposed that the influence of particle size fraction and stirring rate on release characteristics is expressed to a great extent through porosity and indirectly through total effective surface area, but the incorporation of highly soluble component i.e. chitosan salt hides these effects on drug release. In conclusion, changes in biopharmaceutical properties due to varying stirring rate and fraction particle size exhibited the same direction as those reported for the microspheres without chitosan, although they are less expressed because of increased experimental variability, likely caused by chitosan.     

膨润土负载壳聚糖制备吸附剂

将壳聚糖与膨润土混合制得一种吸附剂。将其用于染料溶液的脱色、陈醋的澄清、中药注射液中鞣酸的清除等,脱色率为97％,鞣酸脱除率为50％,陈醋的透光率为25．8％。通过X射线衍射图讨论了膨润土的改性机理。改性后膨润土的片状层结构未发生变化,壳聚糖仅仅吸附在膨润土的内外表面。     

三维壳聚糖材料中水的状态与其性能的关系

利用原位沉析法制备了具有层状结构的高强度三维壳聚糖(chitosan,CS)材料,由于CS分子结构中存在大量的亲水基团,容易吸附水分子.通过热分析(TGA,DSC)测试发现吸水后的CS材料中的水分是以3种不同的状态存在,结合水、中间态水和自由水.结合力学性能的方法分析不同状态的水对材料性能的影响.结果表明,结合水和CS以氢键紧密结合,有较好的热稳定性,对材料的力学性能有增强作用;CS棒材在环境中吸附的中间态水相当于一种增塑剂,随着水含量的增加,材料力学性能的下降符合Fermi经验公式;中间态水达到饱和之后,自由水开始出现,自由水和CS之间的作用力很弱,温度较低时会结晶成冰.自由水的渗透与中间态水比对材料的力学性能没有明显的影响.