School of Engineering, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia.
Faraday Discuss. 2016 Oct 6;191:435-464. doi: 10.1039/c6fd00050a. Epub 2016 Jul 25.
A lack in the detailed understanding of mechanisms through which proteins adsorb or are repelled at various solid/liquid interfaces limits the capacity to rationally design and produce more sophisticated surfaces with controlled protein adsorption in both biomedical and industrial settings. To date there are three main approaches to achieve anti biofouling efficacy, namely chemically adjusting the surface hydrophobicity and introducing various degrees of surface roughness, or a combination of both. More recently, surface nanostructuring has been shown to have an effect on protein adsorption. However, the current resolution of experimental techniques makes it difficult to investigate these three phase systems at the molecular level. In this molecular dynamics study we explore in all-atom detail the adsorption process of one of the most surface active proteins, EAS hydrophobin, known for its versatile ability to self-assemble on both hydrophobic and hydrophilic surfaces forming stable monolayers that facilitate further biofilm growth. We model the adsorption of this protein on organic ligand protected silica surfaces with varying degrees of chemical heterogeneity and roughness, including fully homogenous hydrophobic and hydrophilic surfaces for comparison. We present a detailed characterisation of the functionalised surface structure and dynamics for each of these systems, and the effect the ligands have on interfacial water, the adsorption process and conformational rearrangements of the protein. Results suggest that the ligand arrangement that produces the highest hydrophilic chain mobility and the lack of significant hydrophobic patches shows the most promising anti-fouling efficacy toward hydrophobin. However, the presence on the protein surface of a flexible loop with amphipathic character (the Cys3-Cys4 loop) is seen to facilitate EAS adsorption on all surfaces by enabling the protein to match the surface pattern.
在各种固/液界面上，蛋白质吸附或排斥的机制的详细理解的缺乏限制了在生物医学和工业环境中合理设计和生产具有控制蛋白质吸附能力的更复杂表面的能力。迄今为止，实现抗生物污染效果有三种主要方法，即化学调节表面疏水性和引入不同程度的表面粗糙度，或两者的组合。最近，表面纳米结构化已被证明对蛋白质吸附有影响。然而，目前的实验技术分辨率使得难以在分子水平上研究这些三相系统。在这项分子动力学研究中，我们详细探讨了最具表面活性的蛋白质之一，EAS 疏水蛋白的吸附过程，该蛋白因其在疏水性和亲水性表面上自组装形成稳定单层的多功能能力而闻名，这有助于进一步生物膜生长。我们在具有不同化学异质性和粗糙度的有机配体保护的二氧化硅表面上模拟了这种蛋白质的吸附，包括完全均匀的疏水性和亲水性表面作为比较。我们对这些系统中的每一个进行了功能化表面结构和动力学的详细特征描述，以及配体对界面水、蛋白质吸附过程和构象重排的影响。结果表明，产生最高亲水性链迁移率且没有明显疏水区的配体排列显示出对疏水蛋白最有前途的抗污染效果。然而，在蛋白质表面上存在具有两亲性特征的柔性环（Cys3-Cys4 环）被认为通过使蛋白质能够匹配表面图案而促进 EAS 在所有表面上的吸附。
