EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Spider silk is one of nature’s most fascinating materials and has attracted vivid attention due to its strength, toughness, and elasticity [1]. The application of the dragline silk of spider genus Nephila as a filament for nerve guidance conduits has led to promising results in nerve regeneration [2]. However, the use of spider silk has been phenomenological and the reasons for its success are still not identified. This renders a targeted production of synthetic fibrous luminal fillings such as recombinant silk out of reach. In this work dragline, the cocoon silk of Nephila edulis, as well as the connecting and attaching silk of Avicularia avicularia were investigated [3]. Scanning electron microscopy was employed to study the size and morphology of the fibers, while Raman spectroscopy in native state and aqueous environment revealed the secondary protein structures. The results indicate that the difference in the diameter of the silk fibers does not impact the adhesion of cells. However, the attaching silk shows a lower β-sheets content, crucial for the stiffness of the silk. Therefore, the flexible attaching silk fibers adhere to each other when placed in liquid, leading to the generation of cell agglomerations. This direct comparison demonstrated the crucial role of β-sheets conformation for the guidance properties of natural spider silk, providing essential insights into the necessary material properties for the integration of fibrous luminal fillings in nerve guidance conduits.
[1] L. Römer, et al., The elaborate structure of spider silk, Prion, 2 (2008) 154-161.
[2] T. Kornfeld, et al., Spider silk nerve graft promotes axonal regeneration on long distance nerve defect in a sheep model, Biomaterials, 271 (202)1 120692.
[3] A. Naghilou, et al., Correlating the secondary protein structure of natural spider silk with its guiding properties for Schwann cells, Materials Science and Engineering: C, 116 (2020) 111219.