Anderson Travers H, Yu Jing, Estrada Abril, Hammer Malte U, Waite J Herbert, Israelachvili Jacob N
Department of Chemical Engineering, University of California, Santa Barbara, CA 93106, USA.
Adv Funct Mater. 2010 Dec 8;20(23):4196-4205. doi: 10.1002/adfm.201000932.
Mussels use a variety of 3, 4-dihydroxyphenyl-l-alanine (DOPA) rich proteins specifically tailored to adhering to wet surfaces. Synthetic polypeptide analogues of adhesive mussel foot proteins (specifically mfp-3) are used to study the role of DOPA in adhesion. The mussel-inspired peptide is a random copolymer of DOPA and N(5) -(2-hydroxyethyl)-l-glutamine synthesized with DOPA concentrations of 0-27 mol% and molecular weights of 5.9-7.1 kDa. Thin films (3-5 nm thick) of the mussel-inspired peptide are used in the surface forces apparatus (SFA) to measure the force-distance profiles and adhesion and cohesion energies of the films in an acetate buffer. The adhesion energies of the mussel-inspired peptide films to mica and TiO(2) surfaces increase with DOPA concentration. The adhesion energy to mica is 0.09 μJ m(-2) mol(DOPA) (-1) and does not depend on contact time or load. The adhesion energy to TiO(2) is 0.29 μJ m(-2) mol(DOPA) (-1) for short contact times and increases to 0.51 μJ m(-2) mol(DOPA) (-1) for contact times >60 min in a way suggestive of a phase transition within the film. Oxidation of DOPA to the quinone form, either by addition of periodate or by increasing the pH, increases the thickness and reduces the cohesion of the films. Adding thiol containing polymers between the oxidized films recovers some of the cohesion strength. Comparison of the mussel-inspired peptide films to previous studies on mfp-3 thin films show that the strong adhesion and cohesion in mfp-3 films can be attributed to DOPA groups favorably oriented within or at the interface of these films.
贻贝利用多种富含3,4 - 二羟基苯丙氨酸（DOPA）的蛋白质，这些蛋白质是专门为附着在潮湿表面而定制的。贻贝足丝蛋白（特别是mfp - 3）的合成多肽类似物用于研究DOPA在黏附中的作用。受贻贝启发的肽是DOPA和N(5) - (2 - 羟乙基)-L - 谷氨酰胺的无规共聚物，合成时DOPA浓度为0 - 27 mol%，分子量为5.9 - 7.1 kDa。受贻贝启发的肽的薄膜（3 - 5纳米厚）用于表面力仪（SFA），以测量在醋酸盐缓冲液中薄膜的力 - 距离曲线以及粘附能和内聚能。受贻贝启发的肽薄膜与云母和TiO₂表面的粘附能随DOPA浓度增加而增加。与云母的粘附能为0.09 μJ m⁻² mol(DOPA)⁻¹，且不依赖于接触时间或负载。与TiO₂的粘附能在短接触时间时为0.29 μJ m⁻² mol(DOPA)⁻¹，接触时间>60分钟时增加到0.51 μJ m⁻² mol(DOPA)⁻¹，这表明薄膜内发生了相变。通过添加高碘酸盐或提高pH值将DOPA氧化为醌形式，会增加薄膜厚度并降低内聚力。在氧化薄膜之间添加含硫醇的聚合物可恢复部分内聚强度。将受贻贝启发的肽薄膜与先前关于mfp - 3薄膜的研究进行比较表明，mfp - 3薄膜中的强粘附力和内聚力可归因于这些薄膜内部或界面处取向良好的DOPA基团。
