An Image-Analysis-Based Method for the Prediction of Recombinant Protein Fiber Tensile Strength.

Fredrik G Bäcklund,Jesper Rydén,Anna Rising,Gabriele Greco,Benjamin Schmuck,Gisele H B Miranda,Nicola M Pugno

doi:10.3390/ma15030708

Abstract

Silk fibers derived from the cocoon of silk moths and the wide range of silks produced by spiders exhibit an array of features, such as extraordinary tensile strength, elasticity, and adhesive properties. The functional features and mechanical properties can be derived from the structural composition and organization of the silk fibers. Artificial recombinant protein fibers based on engineered spider silk proteins have been successfully made previously and represent a promising way towards the large-scale production of fibers with predesigned features. However, for the production and use of protein fibers, there is a need for reliable objective quality control procedures that could be automated and that do not destroy the fibers in the process. Furthermore, there is still a lack of understanding the specifics of how the structural composition and organization relate to the ultimate function of silk-like fibers. In this study, we develop a new method for the categorization of protein fibers that enabled a highly accurate prediction of fiber tensile strength. Based on the use of a common light microscope equipped with polarizers together with image analysis for the precise determination of fiber morphology and optical properties, this represents an easy-to-use, objective non-destructive quality control process for protein fiber manufacturing and provides further insights into the link between the supramolecular organization and mechanical functionality of protein fibers.

Highlights

IntroductionProtein fibers, such as those made by spiders or silk moths, have been found to present remarkable properties, and significant research efforts both experimentally and with computer modeling have been spent on elucidating the underlying mechanics of these spectacular materials [1–15]
Silk fibers of different origins can be difficult to tell apart by brightfield light microscopy (Figure 1a–c), but when investigated with polarized microscopy (POM) the level of birefringence is notably much higher for B. mori fibers (Figure 1d) and dragline silk fibers (Figure 1e) as compared to the recombinant fibers investigated in this study (Figure 1f)
Silk moth and spider silk fibers typically have tensile strength values several times that of the recombinant silk fibers investigated in this paper [6,16,19,61,62]

Summary

Introduction

Protein fibers, such as those made by spiders or silk moths, have been found to present remarkable properties, and significant research efforts both experimentally and with computer modeling have been spent on elucidating the underlying mechanics of these spectacular materials [1–15]. Artificial spider silk fibers based on recombinant proteins present a tantalizing option for obtaining protein-based fibers with tailored mechanical properties while avoiding the production issues of native spider silk. As recently reviewed, recombinant silk constructs based on spider silk proteins as well as on silk moth silk are currently being developed and studied for use in a range of applications [25]. Challenges remain in the design and production process to achieve fibers with strengths as high as those that have been found for native silk fibers [26]

Methods

Results

Conclusion