分子动力学模拟多巴在自组装膜上的黏附性

为了更好地理解贻贝在表面的黏附机理,实现水下胶黏,采用分子动力学方法研究了多巴在自组装膜上的黏附性:采用伞形取样和加权柱状图分析方法计算了多巴在不同自组装膜表面的黏附自由能,使用拉伸分子动力学模拟研究了多巴在不同自组装膜表面上黏附后的脱附力.结果表明,多巴在带负电的羧基自组装膜上的黏附能比在带正电的氨基自组装膜上的大,多巴更容易黏附到带负电表面;多巴在带电表面的黏附能比未带电表面的黏附能更强,表明在带电表面黏附更稳定.进一步分析了多巴在不同表面的取向分布,发现多巴与不同表面相互作用的方式不同:与疏水表面主要通过苯环相互作用;与亲水表面主要通过羟基相互作用;与负电表面主要通过氨基相互作用;与正电表面主要通过羧基相互作用.通过模拟比较了多巴在不同自组装膜上的脱附力,发现多巴在带电表面的脱附力比在未带电表面的大,与黏附能的趋势一致.对比4种非带电表面的脱附力,发现多巴在疏水性甲基自组装膜表面的脱附力最大,黏附更稳定,随着表面疏水性的增加,脱附力增大,黏附稳定性增强.本工作可为研发新型水下胶黏剂提供理论指导.     

聚多巴胺对材料表面功能化的研究及应用进展

蚌类蛋白质结构中起黏附作用的为多巴(DOPA)分子,其衍生物——聚多巴胺(PDA)常作为黑色素类似物被广泛应用于各领域。虽然目前PDA的形成机理仍很难被明确阐述,但这并不阻碍其在各个领域发挥强大的功效。由于PDA既具有强黏附性又富含各种官能团,其可在不同材质表面进一步反应形成功能层,从而实现对材料表面的功能化改性。鉴于科研工作者对PDA的浓厚兴趣,本文综述了其发现、形成机理的发展过程以及PDA功能化纳米粒子的研究,包括PDA功能化金属纳米材料、还原石墨烯材料、磁性纳米粒子和PDA纳米材料,展望了其发展前景。     

基于多巴胺表面改性技术研究现状

海洋贻贝类生物通过足丝分泌的黏附蛋白,在潮湿环境中可以短时间固化,并紧固黏附在基质表面.研究表明,3,4-二羟基-L-苯基丙氨酸(多巴,DOPA)是这种黏附蛋白中的重要组成部分.多巴胺(DA)作为DOPA的一种衍生物,拥有同样的强黏附性.且多巴胺的自聚合产物聚多巴胺(PDA)存在许多官能团,如邻苯二酚、胺、亚胺,这些官...     

动态硼酸酯键管控邻苯二酚基团与功能黏附性高分子设计

“黏附”是一种普遍存在的多尺度相互作用,其实质是界面处化学键、氢键或范德华力等的形成.近年来,在贻贝仿生的基础上将黏性因子邻苯二酚基团嵌入到动态硼酸酯聚合物中,成为了功能黏附性高分子的重要发展方向.本专论从分子黏附、微/纳表面黏附和宏观表面黏附3个尺度,介绍硼酸酯键管控邻苯二酚基团在高分子材料功能化方面的研究进展.分子黏附,主要讨论硼酸酯聚合物中邻苯二酚基团与分子或离子相互作用规律及其对材料形貌和刺激响应性能的调控;微/纳表面黏附,论述硼酸酯聚合物体系超分子驱动力和组装机制,介绍其在微/纳材料功能化改性方面的研究进展;宏观表面黏附,讨论硼酸酯键管控邻苯二酚基团与黏附性能调控的关联规律,介绍硼酸酯聚合物功能黏附材料在宏观组装、攀爬机器人领域的应用.最后,从新型硼酸酯聚合物设计、动态键精准管控和器件化应用的角度,对该领域未来前景和发展趋势做出了展望.     

富勒烯功能高分子材料的制备与性能研究

对富勒烯功能高分子材料的制备、表征及其性能研究已成为光前国际上的前沿领域之一。从合成角度考虑,以不同的方法对Ｃ６０进行高分子修饰可得到结构、性质各异的富勒烯高分子衍生物,对于研究如何更好地控制Ｃ６０高分子衍生物的结构,探讨了有Ｃ６０参与的聚合反应的机理以及Ｃ６０在高分子衍生物中的作用无疑是很有帮助的。从应用角度考虑,Ｃ６０引入高分子中必将导致新型聚合物的产生。这些新型聚合物表现出许多独特而极具应用     

壳聚糖及其衍生物在组织工程中的应用

壳聚糖由于具有良好的生物相容性、生物可降解性以及具有可反应的活性基团,因而在生物、医学等领域具有广泛的研究和应用。随着组织工程学研究的深入,壳聚糖及其衍生物材料作为天然高分子组织工程支架越来越受到重视,综述了近年来国内外壳聚糖及其衍生物在组织工程上的研究和应用情况,包括壳聚糖及其衍生物支架材料的制备方法、壳聚糖的改性以及壳聚糖复合材料等。     

聚多巴胺涂层的研究与应用进展

多巴胺在有氧化剂且弱碱性环境下会发生自聚合形成聚多巴胺,聚多巴胺能够在多种基底材料(包括贵金属、金属氧化物、无机及有机高分子材料等)表面实现黏附形成聚多巴胺涂层,基于聚多巴胺涂层中含有大量可以参与反应官能团的特点,聚多巴胺涂层表面可以进行二次修饰从而制备功能性材料表面,也可以基于多巴胺/聚多巴胺与功能性物质之间相互作用,一步法制备功能性材料表面。近些年来,基于聚多巴胺涂层发展起来的两步修饰法和多巴胺一步共混沉积法在诸多领域得到了应用。本文主要综述了聚多巴胺涂层的最新研究和应用进展。     

高分子固液复合界面与液体黏附调控

受猪笼草口缘区润滑效应启发,将低表面能液体注入高分子微纳米多孔结构中可构筑高分子固液复合界面.与超疏水固体界面相比,固液复合界面展现出独特的浸润性和黏附性.界面黏附是高分子复合材料重要的性质之一,实现界面黏附的精准调控对促进这类材料的发展和应用具有至关重要的作用.本文重点从稳定性调控、方向性调控以及原位可逆调控3个方面综述提升固液复合界面黏附可控性的工作,通过在表面微米结构中组装纳米层状及异质纳米层状结构,提高界面黏附的稳定性;使用界面薄层定向冷冻干燥法、激光刻蚀法以及复型法等方法,构筑具有取向结构的高分子固液复合界面,实现界面黏附的方向性调控;通过在界面中引入快速响应的智能基元,设计智能响应高分子固液复合界面,实现界面黏附的原位可逆调控.最后,概述了这类材料目前存在的问题并展望了其未来发展的方向.     

自组装单分子层对多巴黏附能力的可控性研究

将端基分别带—OH和—CH_3基团的11-巯基-1-十一醇和1-十二烷基硫醇2种硫醇分子按不同摩尔比(1∶0,3∶1,1∶1,1∶3和0∶1)自组装到金片表面,制备了一系列由亲水至疏水的具有不同化学组成的单分子层表面.利用X射线光电子能谱、接触角测试仪和原子力显微镜对其表面性质进行了表征.对单分子层表面分别进行了多巴及液相环境相关的液滴黏附性能研究,发现只含有—OH基团的单分子层表面具有最优越的抗多巴黏附能力,随着表面—OH基团的减少,多巴的黏附能力增强,—CH_3基团的引入明显增强了多巴在表面的黏附能力;还发现只含有—OH的单分子层表面具有最大的液滴黏附性能,随着表面—OH基团的减少,多巴依附的液相环境中的液滴对表面的黏附能力越来越弱,—CH_3基团的引入明显降低了表面的水滴黏附能力.实验结果表明,单一的—OH或—CH_3单分子层表面很难同时具有既抗多巴又抗液滴黏附的性能,而含有复合官能团的单分子层表面则可以达到这种双重效果.本文研究可为适应特定环境的抗黏附材料的设计与制备提供依据.     

X射线光电子能谱技术在高分子材料摩擦化学研究中的应用

X射线光电子能谱技术(XPS)是材料表面分析的重要手段,其近年的快速发展促进了表面化学领域研究的深入.高分子及其复合材料在摩擦学性能方面具有普遍的优势,通过XPS对高分子及其复合材料摩擦表面的分析,可以确定摩擦过程的化学变化,并对改进材料的摩擦学性能起到理论的指导作用.作者主要介绍XPS技术的基本原理,及其在高分子与复合材料摩擦学性能研究中的应用.     

Mussel Inspired In Situ Preparation of Antibacterial Silver Nanoparticles by DOPA-Containing Silk Fibroin

Silver nanoparticles (AgNPs) attract a great deal of attention for potent antibacterial capacity, but their use is challenged by limited stability. Inspired by the adhesive and redox properties of the mussel foot proteins containing L -3,4-dihydroxyphenylalanine (DOPA), a facile strategy for in situ synthesis of AgNPs using DOPA-containing fibroin is developed. Tyrosine residues in fibroin are transformed into DOPA via biomimetic synthesis method with content of 0.55 mol%. In situ synthesis generates stable and small AgNPs through DOPA bound in fibroin as a reducing and stabilizing agent. Narrow size distribution with average diameter of 20 nm and excellent monodispersity are obtained. Cross-linking with lysine increases the content of β-sheet to form hydrogel and achieves gradual release of silver. The material exhibits excellent antibacterial properties against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. It can be potentially applied in biological and medical fields to treat bacterial infections.     

仿贻贝粘性高分子的应用进展

海洋贻贝类生物的足丝分泌蛋白几乎能够在所有基底材料上实现高强度、高韧性的粘附,且不受水或者潮湿环境影响。这种环境友好、条件温和的高效生物粘附剂引起了研究人员的兴趣,尤其在粘附机理和应用前景方面更是研究人员关注的重点。大量研究表明,贻贝超强的粘附能力与其分泌的粘附蛋白中高含量的3,4-二羟基苯丙氨酸(多巴,DOPA)单元相关。受贻贝粘附蛋白的启发,人们研究发现,多巴胺(DA)分子具有与之相似的官能团,聚合后有相似分子结构,使用聚多巴胺替代聚多巴,可以在基体表面达到相似的粘附性能。本文简单介绍了仿贻贝粘性物质中的代表多巴胺自聚合形成聚多巴胺(PDA)与粘附机理,并重点介绍了近年来DOPA衍生物在表面改性、催化、生物防污及生物医学领域的应用和前景。     

Polymer composition and substrate influences on the adhesive bonding of a biomimetic, cross-linking polymer

Hierarchical biological materials such as bone, sea shells, and marine bioadhesives are providing inspiration for the assembly of synthetic molecules into complex structures. The adhesive system of marine mussels has been the focus of much attention in recent years. Several catechol-containing polymers are being developed to mimic the cross-linking of proteins containing 3,4-dihydroxyphenylalanine (DOPA) used by shellfish for sticking to rocks. Many of these biomimetic polymer systems have been shown to form surface coatings or hydrogels; however, bulk adhesion is demonstrated less often. Developing adhesives requires addressing design issues including finding a good balance between cohesive and adhesive bonding interactions. Despite the growing number of mussel-mimicking polymers, there has been little effort to generate structure-property relations and gain insights on what chemical traits give rise to the best glues. In this report, we examine the simplest of these biomimetic polymers, poly[(3,4-dihydroxystyrene)-co-styrene]. Pendant catechol groups (i.e., 3,4-dihydroxystyrene) are distributed throughout a polystyrene backbone. Several polymer derivatives were prepared, each with a different 3,4-dihyroxystyrene content. Bulk adhesion testing showed where the optimal middle ground of cohesive and adhesive bonding resides. Adhesive performance was benchmarked against commercial glues as well as the genuine material produced by live mussels. In the best case, bonding was similar to that obtained with cyanoacrylate "Krazy Glue". Performance was also examined using low- (e.g., plastics) and high-energy (e.g., metals, wood) surfaces. The adhesive bonding of poly[(3,4-dihydroxystyrene)-co-styrene] may be the strongest of reported mussel protein mimics. These insights should help us to design future biomimetic systems, thereby bringing us closer to development of bone cements, dental composites, and surgical glues.     

Intrinsic Surface‐Drying Properties of Bioadhesive Proteins

Sessile marine mussels must “dry” underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force‐free approach to measuring molecular‐level interaction through surface‐water diffusivity, different mussel foot proteins were found to have different abilities to evict hydration layers from surfaces—a necessary step for adsorption and adhesion. It was anticipated that DOPA would mediate dehydration owing to its efficacy in bioinspired wet adhesion. Instead, hydrophobic side chains were found to be a critical component for protein–surface intimacy. This direct measurement of interfacial water dynamics during force‐free adsorptive interactions at solid surfaces offers guidance for the engineering of wet adhesives and coatings.     

Surface modification of boron nitride via poly (dopamine) coating and preparation of acrylonitrile‐butadiene‐styrene copolymer/boron nitride composites with enhanced thermal conductivity

A biology‐inspired approach was utilized to functionalize hexagonal boron nitride (h‐BN), to enhance the interfacial interactions in acrylonitrile‐butadiene‐styrene copolymer/boron nitride (ABS/BN) composites. The poly (dopamine), poly (DOPA) layer, was formed on the surface of BN platelets via spontaneously oxidative self‐polymerization of DOPA in aqueous solution. The modified BN (named as mBN) coated with poly (DOPA) was mixed with ABS resin by melting. The strong interfacial interactions via π‐π stacking plus Van der Waals, both derived from by poly (DOPA), significantly promoted not only the homogeneous dispersion of h‐BN in the matrix, but also the effective interfacial stress transfer, leading to improve the impact strength of ABS/mBN even at slight mBN loadings. A high thermal conductivity of 0.501 W/(m·K) was obtained at 20 wt% mBN content, reaching 2.63 times of the value for pure ABS (0.176 W/(m·K)). Meanwhile, the ABS/mBN composites also exhibited an excellent electrical insulation property, which can be expected to be applied in the fields of thermal management and electrical enclosure.     

EPR investigation and spectral simulations of iron-catecholate complexes and iron-peptide models of marine adhesive cross-links

Electron paramagnetic resonance (EPR) spectra are presented for iron complexes of catecholate, tironate, and a 3,4-dihydroxyphenylalanine (DOPA)-containing peptide of sequence Ac-Ala-DOPA-Thr-Pro-CONH2 ("AdopaTP"). This peptide was prepared to model potential metal-protein cross-links in the adhesive used by marine mussels, Mytilus edulis, for affixing themselves to surfaces. Spectra are shown for iron bound to each ligand in mono, bis, and tris coordination environments. For example, the catecholate complexes {Fe(cat)}, {Fe(cat)2}, and [Fe(cat)3]3- are provided. Detailed simulations are presented to describe the origin of spectra for the iron-catecholate and iron-peptide species, which show that the spectral features can be accounted for only with the inclusion of D- and E-strain. The spectroscopy of each compound is shown under both anaerobic and aerobic conditions. When exposed to air, the high-spin Fe3+ signal of [Fe(AdopaTP)3]3- decreases and an organic radical is formed. No other sample exhibited an appreciable radical signal. These data are discussed in light of the biomaterial synthesis carried out by marine mussels.     

Convenient synthesis of acetonide-protected 3,4-dihydroxyphenylalanine (DOPA) for Fmoc solid-phase peptide synthesis

We report a facile approach to the synthesis of acetonide and Fmoc-protected 3,4-dihydroxyphenylalanine (DOPA), Fmoc-DOPA(acetonide)-OH. By protecting the amino group of DOPA with a phthaloyl group and the carboxyl group as a methyl ester, acetonide protection of the catechol of DOPA derivative was realized in the presence of p-toluenesulfonic acid. Following removal of protecting groups, the intermediate was converted to Fmoc-DOPA(acetonide)-OH, which was successfully incorporated into a short DOPA-containing peptide, derived from marine tubeworm cement proteins Pc1 and Pc2.     

DOPA在聚乙烯微孔膜上的自聚合及肝素固定化

在溶液条件下,左旋3,4-二羟基苯丙氨酸(L-DOPA,或L-多巴)能在固体材料表面自发聚合,形成强力附着于材料表面的poly(DOPA)层.基于L-DOPA的这一特性,对聚乙烯(PE)微孔膜进行了表面改性,得到了PE/poly(DOPA)复合膜,并进一步通过poly(DOPA)层上的反应性基团将肝素共价固载在PE微孔膜上.X光电子能谱(XPS)分析结果证实了poly(DOPA)和肝素的固定,接触角测量数据表明膜的亲水性得到了显著提高.     

Spectroscopic Characterisation of Metallo-Cyclodextrins for Potential Chiral Separation of Amino Acids and L/D-DOPA

The derivatives 6-Deoxy-6-[1-(2-amino)ethylamino]-β-Cyclodextrin (CDEn), 6-Deoxy-6-[1-(3-amino)propylamino]-β-Cyclodextrin (CDPn) and 6-Deoxy-6-[1-(4-amino)butylamino]-β-Cyclodextrin (CDBn) were assessed with a view to demonstrating that increasing the chain length of the diaminoalkane moiety can affect the chiral selectivity of the metallo-complexes of these materials. It was shown that IR and Raman spectroscopies can be used to characterise these compounds. The results obtained from the electronic absorption spectra suggested the formation of CuCDAm binary complexes and that the derivatives CDEn and CDPn act as bidentate ligands while CDBn acts as a monodentate ligand due to its longer alkane chain. This study also showed that in the ternary complexes with DOPA there is further coordination of the metal ion to the amino nitrogen atom and the hydroxyl oxygen atom of the drug. On the basis of the results of the circular dichroic spectroscopic studies it was suggested that CuCDEn is the better enantioselective material for DOPA and it acts in a multi-site recognition manner, utilising the inclusion properties of the CD cavity in cooperation with the coordination properties of the metal ion.     

A novel and efficient synthesis of DOPA and DOPA peptides by oxidation of tyrosine residues with IBX

An efficient route to 3,4-dihydroxylphenylalanine (DOPA) and DOPA peptides was described by oxidation of l-tyrosine and l-tyrosine derivatives with 2-iodoxybenzoic acid (IBX). DOPA was obtained after an situ reduction of the corresponding ortho-quinone with sodium dithionite. Oxidation reactions proceeded in good yields and high chemo- and regio-selectivity. The chirality of the DOPA residue was retained under the reaction conditions. The efficiency and the selectivity of the reaction were successfully tested using recyclable polymer-supported IBX.