Continuous production of tough keratin fibers via high recovery of protein secondary structures.

10,12-Pentacosadiynoic acid (PCDA) monomers were mixed with polyurethane (PU) or poly(ethylene oxide) (PEO) and the mixtures were electrospun to obtain composite nanofibers that were then photopolymerized via ultraviolet radiation, resulting polydiacetylene (PDA) in the nanofibers. The PDA demonstrated color-changing properties in the presence of Escherichia coli, which exhibited potential for developing flexible colorimetric biosensors for medical textiles. Phase separation was found in the PEO-PDA fibers, resulting in amorphous PEO accumulation at the fiber surface. In contrast, the PU-PDA fibers demonstrated a homogeneous microstructure throughout the fibers. Tensile test results suggested a molecular orientation in the PU-PDA fibers that significantly improved the mechanical properties of the fibers. The presence of PDA in the matrix polymer reduced the overall strength and breaking elongation of both composite nanofibers in comparison to 100% PEO and PU fibers. A single PU-PDA fiber showed significantly higher stiffness and modulus than a single PEO-PDA fiber. Force-distance curve analysis suggested that the PU-PDA fibers exhibited an elastic deformation. In a comparison, the PEO-PDA fibers were brittle and showed low modulus. The results of structural and mechanical properties suggest that the PU-PDA nanofibers are a promising composite for developing nonadherent, durable, and flexible colorimetric biosensors used in medical textiles.

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