Silk fiber is renowned for its superb mechanical properties, such as over 7 times the toughness of Kevlar 49 Fibre. As the spider silk is tougher than any man-made fiber, there is a lot to be learned from spider silk. Recently, it has been reported that a large portion of the properties of silk is from naturally formed nano-fishnet structures of silk, but neither its formation mechanism nor its formation condition has been explained. Here, we show how the formation and disappearance of nano-fishnet of silk is determined by humidity, and how the humidity-dependency of nano-fishnet formation can be overcome by changing density of Arginine through sequence mutation. We demonstrate that the nano-fishnet-structured silk exhibits higher strength and toughness than its counterparts. This information on controllable nano-fishnet formation of silk is expected to pave the way for development of protein and synthetic fiber design. Statement of significance: Silk fibers are a very interesting material in that it exhibits superb mechanical properties such as 7 times the toughness of Kevlar 49 Fibre, despite being only composed of proteins. Therefore, it is important that we understand the principle of its high mechanical properties so that it may be applied in designing synthetic fibers. Recently, it has been reported that a large portion of its mechanical property comes from its nano-fishnet structures, but no detailed explanation on the condition or mechanism of formation. Through molecular dynamic simulations, we simulated the nano-fishnet formation of silk and analyzed the condition and mechanism behind it, and showed how the formation of nano-fishnet structures could be controlled by changing the density of Arginine residues. Our study provides information on fiber enhancement mechanism that could be applied to synthetic and protein fiber design.
Bibliographical noteFunding Information:
This study was supported by the National Research Foundation of Korea (NRF) under grant number of NRF-2019R1A2C1086103 and NRF-2020R1I1A1A01073771 and funded by the Ministry of Science, ICT & Future Planning and by the Technology Innovation Program 20012422 funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).
- Fiber design
- Molecular dynamics simulation
- Nano-fishnet structure
- Spider silk
ASJC Scopus subject areas
- Biomedical Engineering
- Molecular Biology