医用高氮无镍奥氏体不锈钢的制备与生物相容性研究

主要探讨不同含氮量的无镍奥氏体不锈钢材料对血管内皮细胞及血小板粘附的影响。通过溶血率和血小板粘附试验考察不同含氮量的无镍奥氏体不锈钢材料的血液相容性;通过MTT试验和细胞粘附试验考察不同含氮量的无镍奥氏体不锈钢材料的细胞相容性。结果表明不同含氮量的无镍奥氏体不锈钢材料的溶血率都低于国家标准的5%,对血小板粘附的影响不显著;粘附在高氮无镍奥氏体不锈钢材料表面的血管内皮细胞数量均多于钛合金材料,且细胞生长状态良好;细胞毒性试验表明,不同含氮量的高氮无镍奥氏体不锈钢材料和对照组钛合金材料对血管内皮细胞没有产生明显的毒副作用。     

一种新型医用高氮无镍不锈钢的生物相容性研究

研究了成骨细胞及血小板在不同氮含量的新型高氮无镍奥氏体不锈钢材料表面的粘附及细胞毒性表现。通过血小板粘附实验考察不同氮含量的高氮无镍奥氏体不锈钢材料的血液相容性;通过MTT实验和细胞粘附实验考察不同氮含量的高氮无镍奥氏体不锈钢材料的细胞相容性。结果表明,不同氮含量的高氮无镍奥氏体不锈钢材料对血小板粘附的影响不显著;不同氮含量的无镍不锈钢材料对成骨细胞的生长、形态和增殖不构成伤害,且氮含量对细胞的粘附影响并不显著;细胞毒性实验表明,高氮无镍奥氏体不锈钢和对照组钛合金材料性能稳定,对成骨细胞的生长没有产生明显的毒副作用。     

单壁碳纳米管无纺膜的抗凝血性能研究及其对血液系统中植入性假体的意义

以血液接触环境下的应用为目标，研究了单壁碳纳米管无纺膜的抗凝血性能。通过扫描电镜(SEM)观察和表面元素分析，研究了与凝血过程密切相关的纤维蛋白原、白蛋白以及新鲜血浆在单壁碳纳米管无纺膜表面的吸附行为，并利用SEM和荧光标记流式细胞分析技术(FCM)，从血小板活化形态和血小板膜糖蛋白的构型变化两个方面分析了单壁碳纳米管无纺膜对血小板的作用。实验结果显示，单壁碳纳米管无纺膜对血液中的纤维蛋白分子原具有明显的倾向性吸附，但是并没有像已有的大部分生物材料一样引起明显的后续血小板粘附和活化，材料与血浆接触后，表面上没有观察到可辨识的血小板粘附与活化，富血小板血浆(PRP)中活化血小板在5％左右，表明该材料具有独特的抑制血小板粘附、活化和聚集的抗凝血性能。这种优异的抗凝血性能在血液接触环境中的人工器官、组织替代物、以及可植入器件等方面具有巨大的潜在应用价值。     

生物材料对细胞生物学行为的影响

随着细胞生物学、基因工程等研究领域的发展,临床使用的生物医用材料已经由单纯的生物材料制成的植人物,发展成细胞与生物材料的复合物.生物医用材料不仅应具备生物安全性、生物相容性、血液相容性,还应该具有细胞外基质的作用.本文综述了生物材料作为细胞外基质,对细胞粘附、细胞生长及细胞凋亡的影响.     

胶原模拟多肽对L929细胞粘附的影响

设计合成了3种模拟胶原三螺旋结构或/和整合素识别位点的胶原模拟多肽(CMP),对其进行体外细胞相容性评价,研究其对小鼠成纤维细胞(L929)生长、粘附的影响。实验证实,3种CMP对成纤维细胞生长无明显的细胞毒性反应;3种包被胶原模拟多肽的基底均能在一定程度上促进细胞粘附、生长,具有良好的细胞粘附率和细胞附着形态,其中包含三螺旋结构和整合素识别位点的CMP27具有更好的促粘附效果,细胞粘附数量和形态与胶原接近。初步研究结果证实,胶原三螺旋结构与整合素识别位点共同作用促进L929细胞粘附。因此,CMP可以有效促进细胞粘附,有望作为粘附剂应用于生物医学领域,可为设计以多肽为基础的生物活性材料提供新的研究思路。     

三种生物碳素材料表面的血小板粘附研究

介绍了生物碳素材料的血液相容性的研究概况 ,研究了血小板在石墨、金刚石膜和类金刚石膜材料表面的粘附行为 ,结果表明 ,血小板粘附后的形态指数大小为 :石墨 >金刚石膜 >类金刚石膜。从一定角度定性地得出 :类金刚石膜的血液相容性优于金刚石膜 ,金刚石膜的血液相容性优于石墨     

激光脉冲能量对四面体非晶碳薄膜的结构及血液相容性的影响

采用脉冲激光方法制备了sp3/sp2不同比率的四面体非晶碳薄膜.利用拉曼光谱、紫外可见光谱等材料表征方法, 研究了脉冲激光能量对四面体非晶碳薄膜的微结构及血液相容性的影响.结果表明:脉冲激光能量显著影响四面体非晶碳薄膜中sp3/sp2的比率,调控单脉冲激光能量范围为150～250mJ,可使薄膜的光学带隙从1.41～2.44eV发生变化.血小板粘附实验和动态凝血实验表明制得的薄膜具有优良的血液相容性.分析了四面体非晶碳薄膜的抗凝血机理.     

RGD修饰钛表面对人牙龈成纤维细胞初期黏附和铺展的影响

用羰基二咪唑(1,1'-carbonyldiimidazole,CDI)将含RGD的短肽共价连接到纯钛表面,研究接枝后的钛表面对原代培养的人牙龈成纤维细胞(human gingival fibroblasts,HGF)初期黏附和铺展的影响.结果表明,RGD修饰的纯钛表面粘附的细胞数比未修饰钛表面多,细胞铺展面积比钛表面的大,应力纤维的形成比钛表面早.RGD接枝钛表面更有利于人牙龈成纤维细胞的粘附,改善了纯钛的生物相容性.     

磷脂胆碱仿生修饰聚乳酸及其生物学评价

通过自由基聚合反应将马来酸酐接枝到聚(D,L-乳酸)(PDLLA)侧链上,然后通过引入的活性反应基团马来酸酐与甘油磷脂胆碱反应,实现磷脂胆碱对聚乳酸的整体仿生修饰。采用红外光谱和核磁共振碳谱对磷脂胆碱修饰聚乳酸进行了表征。生物降解实验表明,该功能化聚乳酸具有明显抑制酸致降解作用。体外细胞形貌观察证实磷脂胆碱修饰的聚乳酸具有良好的细胞相容性。同时,蛋白吸附和血小板粘附实验表明,该聚合物具有良好的血液相容性。该改性聚乳酸可望用作组织工程支架及血液接触类植入体。     

多巴胺表面修饰胶原膜促进细胞粘附和增殖的研究

多巴胺已经被广泛地用于材料的表面修饰改性,能够提高材料的生物相容性,赋予材料新的反应活性.为了考察多巴胺表面修饰胶原膜对其机械强度、湿热稳定性、亲水性和生物相容性的影响,对多巴胺自组装表面修饰胶原膜不同时间形成的膜材料进行研究,结果发现,经过多巴胺自组装表面修饰后,胶原保持完整的三股螺旋结构,膜材料的机械强度、湿热稳定性和亲水性均得到提高,而且成纤维细胞更易于在膜上粘附和增殖.     

Sliding-induced adhesion of stiff polymer microfibre arrays. II. Microscale behaviour.

The adhesive pads of geckos provide control of normal adhesive force by controlling the applied shear force. This frictional adhesion effect is one of the key principles used for rapid detachment in animals running up vertical surfaces. We developed polypropylene microfibre arrays composed of vertical, 0.3 microm radius fibres with elastic modulus of 1 GPa which show this effect for the first time using a stiff polymer. In the absence of shear forces, these fibres show minimal normal adhesion. However, sliding parallel to the substrate with a spherical probe produces a frictional adhesion effect which is not seen in the flat control. A cantilever model for the fibres and the spherical probe indicates a strong dependence on the initial fibre angle. A novel feature of the microfibre arrays is that adhesion improves with use. Repeated shearing of fibres temporarily increases maximum shear and pull-off forces.     

Photodetachable Adhesion

Peeling from strong adhesion is hard, and sometimes painful. Herein, an approach is described to achieve both strong adhesion and easy detachment. The latter is triggered, on‐demand, through an exposure to light of a certain frequency range. The principle of photodetachable adhesion is first demonstrated using two hydrogels as adherends. Each hydrogel has a covalent polymer network, but does not have functional groups for bonding, so that the two hydrogels by themselves adhere poorly. The two hydrogels, however, adhere strongly when an aqueous solution of polymer chains is spread on the surfaces of the hydrogels and is triggered to form a stitching polymer network in situ, in topological entanglement with the pre‐existing polymer networks of the two hydrogels. The two hydrogels detach easily when the stitching polymer network is so functionalized that it undergoes a gel–sol transition in response to a UV light. For example, two pieces of alginate–polyacrylamide hydrogels achieve adhesion energies about 1400 and 10 J m^?2, respectively, before and after the UV radiation. Experiments are conducted to study the physics and chemistry of this strong and photodetachable adhesion, and to adhere and detach various materials, including hydrogels, elastomers, and inorganic solids.     

Adhesion and sliding response of a biologically inspired fibrillar surface: experimental observations

Inspired by the adhesion mechanisms of several animal species such as geckos, beetles and flies, several efforts in designing and fabricating surface engineering strategies have been made recently to mimic the adhesive and frictional behaviour of biological foot pads. An important feature of such biological adhesion systems is the ability to switch between strong attachment and easy detachment, which is crucial for animal locomotion. Recent investigations have suggested that such a 'switching' mechanism can be achieved by the elastic anisotropy of the attachment pad, which renders the magnitude of the detachment force to be direction dependent. This suggestion is supported by the observations that the fibres of the foot pads in geckos and insects are oriented at an angle to the base and that geckos curl their toes backwards (digital hyperextension) while detaching from a surface. One of the promising bio-inspired architectures developed recently is a film-terminated fibrillar PDMS surface; this structure was demonstrated to result in superior detachment force and energy dissipation compared with a bulk PDMS surface. In this investigation, the film-terminated fibrillar architecture is modified by tilting the fibres to make the surface vertically more compliant and elastically anisotropic. The directional detachment and the sliding resistance between the tilted fibrillar surfaces and a spherical glass lens are measured: both show significant directional anisotropy. It is argued that the anisotropy introduced by the tilted fibres and the deformation-induced change in the compliance of the fibre layer are responsible for the observed anisotropy in the detachment force.     

Gecko‐Inspired Surfaces: A Path to Strong and Reversible Dry Adhesives

The amazing adhesion of gecko pads to almost any kind of surfaces has inspired a very active research direction over the last decade: the investigation of how geckos achieve this feat and how this knowledge can be turned into new strategies to reversibly join surfaces. This article reviews the fabrication approaches used so far for the creation of micro‐ and nanostructured fibrillar surfaces with adhesive properties. In the light of the pertinent contact mechanics, the adhesive properties are presented and discussed. The decisive design parameters are fiber radius and aspect ratio, tilt angle, hierarchical arrangement and the effect of the backing layer. Also first responsive systems that allow thermal switching between nonadhesive and adhesive states are described. These structures show a high potential of application, providing the remaining issues of robustness, reliability, and large‐area manufacture can be solved.     

金属/高分子涂层附着机理的研究方法

金属/高分子涂层之间的附着机理是一个复杂但又具有重要理论和应用意义的研究内容.最近,纳米改性高分子与金属以及壁虎附着现象和机理的研究正成为热点.对附着强度的测定方法,特别是最近发展起来的微观测试法进行了详细的介绍,比较了这些方法的特点及适用条件;同时,重点介绍了最近几年国内外研究的金属与高分子的附着机理,尤其针对不同附着机理时采用的方法及设备.     

Chemistry of Silanes: Interfaces in Dental Polymers and Composites

The performance and service life of glass-or ceramic-filled polymeric composites depend on the nature of their resin, filler and interfacial phases as well as the efficacy of the polymerization process. The synergy that exists between the organic polymer matrix and the usually inorganic reinforcing filler phase is principally mediated by the interfacial/interphasial phase. This latter phase develops as a result of the dual reactivity of a silane coupling agent, (YRSiX₃), a bifunctional molecule capable of reacting with the silanol groups of glass or ceramic fillers via its silane functional group (–SiX₃) to form Si-O-Si- bonds to filler surfaces, and also with the resin phase by graft copolymerization via its Y functional group, usually a methacrylic vinyl group. In this paper, we explore some of the chemistry of organosilanes, especially that of functional organosilanes (or silane coupling agents as they are commonly known) that are used to mediate interfacial bonding in mineral reinforced polymeric composites. The chemistry of organosilanes can be quite complex involving hydrolytically initiated self-condensation reactions in solvents (including monomers) that can culminate in polymeric silsesquioxane structures, exchange reactions with hydroxylated or carboxylated monomers to form silyl ethers and esters, as well as the formation of silane derived interfaces by adhesive coupling with siliceous mineral surfaces.     

WC—Co硬质合金基体上金刚石薄膜的附着机理研究

金刚石涂层在硬质合金(WC-Co)基体上的附着力,是影响金刚石涂层刀具切削性能和使用寿命的关键因素.采用微波等离子体化学气相沉积(CVD)法在经酸浸蚀脱Co的硬质合金基体上生长金刚石薄膜.通过对金刚石膜/基界面的微观形貌和成分分析,初步认识了金刚石薄膜的附着机理:机械锁合作用对金刚石膜/基附着力有较大贡献;界面热应力和弱中间相的存在是导致金刚石膜自发剥离的主要原因.     

Peeling dynamics of fluid membranes bridged by molecular bonds: moving or breaking

Biological adhesion is a critical mechanical function of complex organisms. At the scale of cell–cell contacts, adhesion is remarkably tunable to enable both cohesion and malleability during development, homeostasis and disease. It is physically supported by transient and laterally mobile molecular bonds embedded in fluid membranes. Thus, unlike specific adhesion at solid–solid or solid–fluid interfaces, peeling at fluid–fluid interfaces can proceed by breaking bonds, by moving bonds or by a combination of both. How the additional degree of freedom provided by bond mobility changes the mechanics of peeling is not understood. To address this, we develop a theoretical model coupling diffusion, reactions and mechanics. Mobility and reaction rates determine distinct peeling regimes. In a diffusion-dominated Stefan-like regime, bond motion establishes self-stabilizing dynamics that increase the effective fracture energy. In a reaction-dominated regime, peeling proceeds by travelling fronts where marginal diffusion and unbinding control peeling speed. In a mixed reaction–diffusion regime, strengthening by bond motion competes with weakening by bond breaking in a force-dependent manner, defining the strength of the adhesion patch. In turn, patch strength depends on molecular properties such as bond stiffness, force sensitivity or crowding. We thus establish the physical rules enabling tunable cohesion in cellular tissues and in engineered biomimetic systems.     

Maximum strength for intermolecular adhesion of nanospheres at an optimal size

Previous studies have emphasized that the adhesion strength between solid objects tends to increase as the characteristic size of the objects decreases and eventually saturates at the theoretical adhesion strength below a critical size scale. Here we show that the adhesion strength between two spheres or between a sphere and a solid half-space actually exhibits a peak value at an optimal size. This optimal size arises owing to a transition between surface- and bulk-dominated interaction regimes at the nanoscale.     

A microfabricated wedge-shaped adhesive array displaying gecko-like dynamic adhesion,directionality and long lifetime

Gecko adhesion has become a paradigmatic example of bio-inspired engineering, yet among the many gecko-like synthetic adhesives (GSAs), truly gecko-like performance remains elusive. Many GSAs have previously demonstrated one or two features of the gecko adhesive. We present a new wedge-shaped GSA that exhibits several gecko-like properties simultaneously: directional features; zero force at detachment; high ratio of detachment force to preload force; non-adhesive default state; and the ability to maintain performance while sliding, even after thousands of cycles. Individual wedges independently detach and reattach during sliding, resulting in high levels of shear and normal adhesion during drag. This behaviour provides a non-catastrophic failure mechanism that is desirable for applications such as climbing robots where sudden contact failure would result in serious falls. The effects of scaling patch sizes up to tens of square centimetres are also presented and discussed. Patches of 1 cm² had an adhesive pressure of 5.1 kPa while simultaneously supporting 17.0 kPa of shear. After 30 000 attachment/detachment cycles, a patch retained 67 per cent of its initial adhesion and 76 per cent of its initial shear without cleaning. Square-based wedges of 20 μm and 50 μm are manufactured in a moulding process where moulds are fabricated using a dual-side, dual-angle lithography process on quartz wafers with SU-8 photoresist as the mould material and polydimethylsiloxane as the cast material.