【作者】 何天贤；

【导师】 邓文礼；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2012， 博士

【摘要】 藤本植物爬山虎是一种具有多种经济价值的攀沿植物，其研究工作已经引起了越来越多人的重视。尽管如此，对其吸盘的研究却是少之又少。爬山虎能利用其卷须的自攀沿来维持直立生长，在卷须末端形成的吸盘可以长久地粘附在各种基底上，而且粘附力还很强大。根据我们的研究，成熟枯干的爬山虎的单个吸盘的平均质量约为0.0005克，与基底的粘附接触面积平均值也只有1.22平方毫米，而粘附力却达到13.7牛顿；单个吸盘在其生长发育过程中能够支撑起由茎、叶、分枝和卷须共同产生的重量高达吸盘自身重量的260倍，能够承载的最大拉力是其自身重量的280万倍。为了充分认识爬山虎吸盘的超级粘附作用，我们系统地研究了爬山虎吸盘的微观结构、化学成分和粘附机理，并在此基础上对吸盘的表面形貌进行了仿生。在扫描电子显微镜实验中，我们发现吸盘刚开始的时候它的表皮细胞是折叠形的，随后它的表面将会发育成密集堆积的气球状。当受到接触刺激后，吸盘会分泌出大量的粘性流体，粘液会穿过表皮细胞的细胞壁积聚在表皮下而形成疱疹，并最终从疱疹爆裂的孔洞中流出。同时，靠近接触点的吸盘表皮细胞将会戏剧性地伸长，而其他的表皮细胞则会保持背斜地分开。在随后的衰老和木质化当中，爬山虎成熟吸盘的表面形貌则呈现出蜂窝状。我们用高效液相色谱/质谱联用的方法初步分离了爬山虎吸盘中的21种有机成分。对这些成分的分析研究表明，这21种化合物中大多数都含有氮、硫、氧元素。含有这几种元素的化合物大都能产生极性，氢键作用可能是吸盘在攀沿过程中产生的一种弱吸附力。另外，火焰原子吸收光谱法鉴定了爬山虎吸盘中含有钾、钠、钙、镁、铁、锰等6种金属元素。其中，钙元素的含量最大，它可能参与爬山虎吸盘所分泌粘液的粘附作用。尽管爬山虎吸盘的优异力学性能已经被认知了很多年，但是国际上并没有系统地研究其微观结构、粘附性能和粘附机理之间的相互关系。我们在系统研究爬山虎吸盘组织结构和粘附力的基础上，提出了界面反应导致吸盘“锚合”的新假说和负压效应形成封闭空间的新模型来描述爬山虎吸盘的粘附机理，吸盘从而以这样的方式与基底之间形成一个完美的粘合。为了评估吸盘表面的两种微观结构在爬山虎攀沿过程中的粘附贡献，我们利用常规氧化铝模板和分级氧化铝模板分别仿生合成了类似于吸盘表面结构的聚苯乙烯阵列柱子和阵列孔洞薄膜。通过类比分析这些表面结构上的粘附力，我们认为未成熟吸盘的柱状细胞起着定位基底并在其表面固定吸附的功能；而在成熟吸盘的蜂窝状大孔结构中，这些海绵状多孔结构有利于粘液的流动和传送，并能显著增强吸盘和基底之间的粘附作用。自然的力量不仅能创造美，更能创造奇迹。理解生物学体系的超级粘附机理是从生物粘附系统获得灵感从而进行仿生设计的先决条件，为了充分了解爬山虎吸盘的超级粘附作用，显然还需要更多实验和理论的探索，本项工作对于进一步深入地研究爬山虎吸盘具有重要的指导意义。更多还原

【Abstract】 Liana Parthenocissus tricuspidata is a versatile climbing plant, which has attracted greatinterest for many years. However, rare attention was paid on the adhesive disc of P.tricuspidata. The self-clinging P. tricuspidata can climb on stone mountains, roadside stonebanks and house outside walls with tendrils to obtain vertical growth. At the end of thetendrils, it develops adhesive discs that attach themselves quite firmly to the substrate.According to our study, a single mature adhesive disc of P. tricuspidata has an average massof only about0.0005g, an average attached area of about1.22mm2and an adhesive force ofabout13.7N but can, on average, support a combined weight of stem, leaf, branchlet, andtendril which is260times greater than its own weight during the growth, and can sustain amaximum pulling force which is2800000times higher than that produced by its own weight.In order to fully realize the super adhesive effect of adhesive disc, we systematically studiedits microstructure, chemical composition and adhesion mechanism, and on this basis, wemimicked the surface morphology of adhesive disc.In our experiment of scanning electron microscopy (SEM), we found that epidermal cellsurfaces of the adhesive disc firstly appeared very folded, but developed into a densely packedpattern of hemispheres. When stimulated, a heavy sticky fluid was secreted; the adhesive fluidpassed through the wall of epidermal cells, accumulating under the cuticle and causing it to ableb, and was finally secreted from the ruptured holes. Meanwhile, epidermal cells nearest thepoint of contact elongated extensively and divided periclinically, whereas the left epidermalcells swelled and underwent anticlinal divisions. During the subsequent senescence andlignifications, the epidermal cells would present a honeycomb-like surface appearance in fullymature adhesive disc.We first used high-performance liquid chromatography/mass spectrometry (HPLC/MS)to preliminarily analyze the chemical composition of adhesive disc. The data analysissuggested that there are at least21components in the adhesive disc of P. tricuspidata. Theformulas demonstrated that most of the21compounds contain nitrogen, sulfur and oxygen.These compounds are widely known for their ability to generate polarity, hydrogen bondingwould be a weak adhesion for P. tricuspidata climbing. In addition,6metal elements (K, Na,Ca, Mg, Fe and Mn) were identified in the adhesive disc of P. tricuspidata. Between them, theCa content is the most and calcium ions may be involved in the process of adhesion.Although the sticking ability of P. tricuspidata has been known for hundreds of years,the component-structure-property relations of adhesive disc are sparsely studied. Based on our experimental studies on the microstructural examinations and adhesive properties of adhesivedisc, we proposed new hypotheses of interface reaction leading to adhesive disc “anchor” andnegative pressure resulting in a closed space to elucidate the mechanism of adhesion, in thisway the adhesive disc has a perfect form closure with the substrate.In order to appraise the adhesive contribution of two nature contact structures of P.tricuspidata, biomimetic polystyrene (PS) pillar-like and honeycomb-like microstructuresinspired by the adhesive disc were prepared via a regular alumina template and hierarchicalalumina template, respectively. Through analogy analysis of the adhesive force on thesebiomimetic surface structures, we believed that the finger-like cells of young adhesive dischave a positioning function for pre-adhesion; and the microchannels inside the matureadhesive disc took charge of the accumulation and transportation of mucilage, thesesponge-like structures of cells and cell clusters enhanced the adhesive strength between theadhesive disc and substrate.The beauty and miracle can be created by a natural power, so understanding thesuper-adhesion mechanism of biological systems is of great scientific significance and aprerequisite for bio-inspired design of adhesive systems. Evidently, more experimental andtheoretical works are imperative to fully understand the super adhesive effect of adhesive discof P. tricuspidata and this work is quite useful for future studies.更多还原