Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, FI-00076 Aalto, Finland.
Centre of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, Post Office Box 16100, 00076 Aalto, Finland.
Langmuir. 2023 Mar 28;39(12):4370-4381. doi: 10.1021/acs.langmuir.2c03442. Epub 2023 Mar 16.
Molecular engineering of protein structures offers a uniquely versatile route for novel functionalities in materials. Here, we describe a method to form highly hydrophobic thin films using genetically engineered spider silk proteins. We used structurally engineered protein variants containing ADF3 and AQ12 spider silk sequences. Wetting properties were studied using static and dynamic contact angle measurements. Solution conditions and the surrounding humidity during film preparation were key parameters to obtain high hydrophobicity, as shown by contact angles in excess of 120°. Although the surface layer was highly hydrophobic, its structure was disrupted by the added water droplets. Crystal-like structures were found at the spots where water droplets had been placed. To understand the mechanism of film formation, different variants of the proteins, the topography of the films, and secondary structures of the protein components were studied. The high contact angle in the films demonstrates that the conformations that silk proteins take in the protein layer very efficiently expose their hydrophobic segments. This work reveals a highly amphiphilic nature of silk proteins and contributes to an understanding of their assembly mechanisms. It will also help in designing diverse technical uses for recombinant silk.
蛋白质结构的分子工程为材料的新型功能提供了一种独特的多功能途径。在这里，我们描述了一种使用基因工程蜘蛛丝蛋白形成高疏水性薄膜的方法。我们使用含有 ADF3 和 AQ12 蜘蛛丝序列的结构工程蛋白变体。使用静态和动态接触角测量来研究润湿性。溶液条件和薄膜制备过程中的周围湿度是获得高疏水性的关键参数，超过 120°的接触角证明了这一点。尽管表面层具有很高的疏水性，但由于添加的水滴，其结构被破坏。在放置水滴的地方发现了类似晶体的结构。为了了解薄膜形成的机制，研究了不同变体的蛋白质、薄膜的形貌和蛋白质成分的二级结构。薄膜中的高接触角表明，丝蛋白在蛋白质层中采取的构象非常有效地暴露了它们的疏水区段。这项工作揭示了丝蛋白的高度两亲性，并有助于理解它们的组装机制。它也将有助于设计重组丝的各种技术用途。
