Bioinspired Fabrication of Polyurethane/Regenerated Silk Fibroin Composite Fibres with Tubuliform Silk-Like Flat Stress–Strain Behaviour

Abstract

Tubuliform silk is one of the seven different types of spider silks, which is well known for its unique tensile behaviour with Flat Tensile Stress-Strain (FTSS) curve. It is found that anisotropic microstructure of β-sheets is responsible for this property. In recent years, bioinspired approaches to engineer fibres supported by modern manufacturing systems have been attracting considerable interest. The present paper aims to investigate a strategy to biomimic the FTSS behaviour of tubuliform silk in synthetic polymer composite fibres by blending polyurethane (PU) and regenerated silk fibroin (RSF) at different ratios. Wet spinning of composite fibres results in the reconstruction of β-sheets in the synthetic fibre matrix. PU/RSF composite fibre at a ratio of 75/25 produce a tensile curve with FTSS characteristics. Secondary structural changes in RSF and interchain directions of β-sheets within the fibre are studied using Fourier Transform Infra-red (FTIR) spectroscopy and Transmission Electron Microscopy (TEM), respectively. Interestingly, results of TEM patterns confirm transverse anisotropic properties of RSF β-sheets. The composite fibres also display tuneable mechanical properties with respect to RSF contents.

Doing What Spiders Cannot—A Road Map to Supreme Artificial Silk Fibers

“…However, if biomimetic spinning processes are desired, the required solubility could be achieved by one or several of the following strategies. First, recent results have shown that mini spidroins containing both terminal domains and a short repetitive region can efficiently be expressed in Escherichia coli and are extraordinarily soluble (50% w/v). , Introducing Ala to Val or Ile substitutions in these proteins could therefore be afforded and still result in soluble target proteins. The mechanical properties of fibers spun from these proteins could match or even outperform those of native silk due to increased intermolecular interactions in the β-crystals.…”

“…below) . Expression and purification of spidroins under benign conditions, as well as subsequent biomimetic spinning protocols, have been developed and shown to recapitulate important events of the assembly process. − However, the mechanical properties of fibers produced in this manner are still inferior to those of the native silk fiber, likely due to the small size of the spidroins used; hence, there is a need for novel ideas on how to produce high-performance spider silk replicas using biotechnological tools.…”

Infrared Invisibility Cloak Based on Polyurethane–Tin Oxide Composite Microtubes

“…This is because as the amount of SnO 2 cluster increases, it interferes with the interaction of the PU polymer chains and the orientation of the PU polymer in the matrix, thus weakening the tensile strength and strain of the PU−SnO 2 composite microtube. 29 To render the PU−SnO 2 composite microtubes hydrophobic, a self-assembled monolayer (SAM) of (1H,1H,2H,2Hheptadecafluorodec-1-yl)phosphonic acid (HDF-PA), which contains a phosphoric acid anchor group, was formed on them. HDF-PA molecules bind strongly to the microtubes through interfacial bonding based on a condensation reaction between their phosphonate groups and SnO 2 on the microtube surface.…”

“…As the SnO 2 content in the microtube increased, the strength and strain values of the PU–SnO 2 composite microtube decreased gradually (strengths of 4.13, 3.00, 2.89, 2.93, 2.54, 2.21, and 1.85 mN tex –1 , respectively, and strains of 466.19, 356.63, 351.39, 350.57, 285.67, 211.05, and 157.92%, respectively, were determined for Microtube 1, Microtube 2, Microtube 3, Microtube 4, Microtube 5, Microtube 6, and Microtube 7). This is because as the amount of SnO 2 cluster increases, it interferes with the interaction of the PU polymer chains and the orientation of the PU polymer in the matrix, thus weakening the tensile strength and strain of the PU–SnO 2 composite microtube …”

Shape Memory Polyurethane-Based Smart Polymer Substrates for Physiologically Responsive, Dynamic Pressure (Re)Distribution

“…Shape fixity enables acquisition of a temporary, deformed shape via a suitable programming process, whereas shape recovery retrieves the original shape via controlled application of a stimulus. 9−12 This shape controllability (i.e., fixity or recovery) is currently at the forefront of multiple research domains spanning biomedical, 13−17 textiles, 18−20 aerospace, 21,22 etc. Primarily in biomedical, SMP are attractive in critical applications including sutures, 23 stents, 24 embolic biomedical devices, 25 drug delivery devices, 26,27 tissue scaffolds, 28,29 and compression stockings.…”