【作者】 张莉；

【导师】 邓文礼；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2014， 博士

【摘要】 爬山虎属植物是一种葡萄科，多年生落叶木质藤本植物。由于其卷须顶端生有吸盘，并能分泌出一种粘性液体，因而可以攀附于岩石、墙壁或是树木等基材表面。我们已经测定了单个吸盘在1.22mm2这么小的面积内竟可以产生13.7N的粘附力。鉴于仿壁虎刚毛的各种仿生胶带的应用，我们期望利用爬山虎属植物独特的粘附性能制备出一种仿生粘附材料，即从结构仿生和成分仿生两个方向入手。在已报道的相关文献中，对于吸盘超微结构的观察已经取得了较大的进展，而对于粘性分泌物的研究却一直停滞不前。正是由于缺乏对粘液成分的充分了解，爬山虎属植物的粘附机理一直都无法得到统一的解释，进而阻碍了爬山虎仿生粘附材料的研究与开发。鉴于此，本论文从现有文献出发，以提取和分离吸盘粘液中的粘性多糖成分为主要研究对象，分别对爬山虎属植物吸盘多糖的提取工艺、分离与纯化、结构表征，以及粘附性能进行了较为系统的研究，具体内容如下：1.利用响应面分析法，建立吸盘多糖提取工艺的数学模型，并对提取条件之间的交互作用进行分析。根据所建立的数学模型进行提取条件的优化，进一步得出提取吸盘粗多糖的最佳工艺条件。2.采用乙醇沉淀法、DEAE-纤维素-32离子交换柱和葡聚糖G-100凝胶柱对粗多糖进行分级与纯化，得到五种吸盘多糖。利用凝胶渗透色谱，测定得到各种吸盘多糖的重均分子量和分子量分布宽度。3.利用三氟乙酸水解、糖醇乙酸酯衍生化法和气相色谱分析，得到了5种吸盘多糖的单糖组成。其中，PT1含有鼠李糖（14.3%）、阿拉伯糖（21.7%）、果糖（30.9%）和半乳糖（33%）；PT2则由阿拉伯糖（19.6%）、果糖（44.2%）和半乳糖（36.1%）组成；PT3中含有5种单糖，分别为鼠李糖（16.1%）、阿拉伯糖（17%）、木糖（12.5%）、果糖（24%）和半乳糖（30.3%）；PT4和PT5主要含有阿拉伯糖、甘露糖、葡萄糖和半乳糖，各单糖之间的摩尔比率分别为28.0:23.0:17.0:32.0和21.4:23.7:25.2:29.7。4.利用红外光谱、高碘酸氧化、Smith降解、甲基化反应和核磁共振波谱，对吸盘多糖的一级结构进行分析，并推测出可能的结构片段。五种多糖均以1,3-连接的半乳糖为主链，分支点在6号氧原子上。5.利用AFM对吸盘多糖的微观形貌进行观察。结果表明，PT1在高浓度下易形成无规聚集体状态，随着浓度的降低，它在云母上的聚集行为也逐渐减弱。随着浓度的降低，吸盘多糖PT2的微观形貌经历了从薄膜-网状结构-无规线团的变化过程。PT3在浓度为1mg/ml时，在云母表面形成球形颗粒，但并非是单个分子，而是多糖分子的聚集体。PT4和PT5在浓度为1μg/ml时，均可形成具有分支或线形的结构。6.利用DLA模型对吸盘多糖形成的树枝状分形结构进行模拟，当边界条件为600600，粘附系数为1，粒子数目达到60000时，树形结构呈现出―枝繁叶茂‖，与实际观察的树形结构极为相似。7.利用AFM力曲线对吸盘多糖的粘附力进行了测定和评估，结果表明，PT2所能达到的最大粘附力为295.8nN，这与一些仿生粘胶和其他攀援植物的粘附力相近，说明PT2是一种潜在的粘性材料，是爬山虎属植物粘附系统的重要组成要素更多还原

【Abstract】 Parthenocissus tricuspidata is a tendril-climber liana, belonging to the family ofVitaceae. Following touch stimulation, the tendrils can firmly adhere to different supportingobjects by flattening against the support surface, becoming adhesive discs in the tip andsubsequently secreting a kind of adhesive compound. The unique adhesion ability of P.tricuspidata has attracted great attentions from scientists since Darwin’s time. Previousstudies mainly focus on microstructure observation, cytochemical studies, attachment strengthquantification and bionic fabrication. The adhesive compound secreted from adhesive discshas been considered to be a kind of polysaccharide. However, there are only few reports aboutthe further details of this adhesive compound. Therefore, the adhesion mechanism of P.tricuspidata has not been completely confirmed and the further studies on the polysaccharidessecreted from adhesive discs are desirable and necessary. Herein, the aim of our study is toextract, isolate, purify and characterize the polysaccharides from adhesive discs of P.tricuspidata. The main contents have been summarized as follows:1. Response surface methodology (RSM) and central composite design (CCD) wereemployed to investigate the effects of extraction conditions on the extraction yield of crudepolysaccharide from adhesive discs. The optimum conditions were extraction time of3h,temperature of90°C and ratio of water to raw material of12:1, respectively. Under theseconditions, the maximum yield is6.642%.2. The water-soluble polysaccharides (PT1, PT2, PT3, PT4and PT5) were obtained fromadhesive discs through pretreatment, extraction with hot water, precipitation by95%ethanol,deproteinization and purification on DEAE-cellulose column and Sephadex G-100column.The homogeneity of polysaccharide was determined by HPGPC and the weight-averagemolecular weights of five polysaccharides were24699、202455、10537、253992and10382Daaccording to the calibration curve, respectively.3. The composition of sugars was determined by acid hydrolysis and GC analysis. PT1was composed of rhamnose (14.3%), arabinose (21.7%), fructose (30.9%) and galactose(33.0%). PT2consisted of arabinose (19.6%), fructose (44.2%) and galactose (36.1%).Besides rhamnose (16.1%), arabinose (17.0%), fructose (24.0%) and galactose (30.3%), PT3 also contained xylose (12.5%). PT4and PT5were composed of arabinose (21.4%), mannose(23.7%), galactose (29.7%) and glucose (25.2%) with the molar ratios of28.0:23.0:32.0:17.0and21.4:23.7:29.7:25.2，respectively.4. The chemical compositions and structures of polysacchrides were identified by aseries of chemical and instrumental methods, e.g. acid hydrolysis, periodate oxidation, Smithdegradation, methylation, IR and NMR spectra. According to the analysis of structureelucidation, they were major composed by (1→3)-linked-Galp backbone with some branchingsites at O-6positions.5. The morphological structures of polysaccharides were investigated by atomic forcemicroscopy (AFM). PT1can easily form the aggregates with irregular shape under the higherconcentration. With the decrease of the concentration, PT1formed a kind of rope structure.PT2formed thin film-network-irregular rope structure along the decrease of concentration.The spherical particles with the diameter ranged from100to150nm were observed from theAFM image of PT3. As shown in the AFM image of PT-A, a long rope-like structure withsome branches is formed on the mica surface and the aggregates, caused by the entangledbranches, are also observed in some areas. The branched and linear rope-like structures areformed on mica surface by PT5.6. We also observed some branch-like structures and dendritic islands with irregularshapes at the edges of three samples, which were the typical fractal structure characterized byself-similarity. The classical Diffusion-Limited Aggregation (DLA) model was suggested todescribe the growth mechanism of the fractal structure. The fractal structure and dendriticislands produced by computer simulations closely approximate the structure obtained fromAFM observation.7. We also evaluate the adhesive property of polysaccharides and the results suggestedthat PT2was a potential bio-adhesive with the highest adhesion force value of295.8nN,compared to other bio-adhesive from animal or plant.更多还原