Wool Keratin for a bioinspired and bio-sustainable use of nanofibres in biomedical field

Keratin is a highly multifunctional and sustainable biopolymer serving various roles in nature due to its multiple properties, wide spectrum of structural designs and impressive performance [1]. Due to their ingenious structuring and tunability across many length scales, keratins may inspire nature-like structures with tailored properties (i.e., biocompatibility, degradability, stiffness) specifically addressed to mimic cell interface and the extracellular matrix of natural tissues [2]. Herein, we propose our recent studies focused on the use of additive technologies like electrospinning to fabricate Wool Keratin (WK) based nanofibers with multiple ionisable side chains to improve cell interactions. WK fibers with preferential alignment were investigated to fabricate functional nanostructured coatings on titanium substrates suitable for innovative biomedical implants/devices [3]. By combining topographical and biochemical signals, WK nanofibres can stimulate the biological activity of fibroblasts thus supporting soft tissue healing around trans-mucosal implants [1,4]. Moreover, when blended with other natural or synthetic polymers, WK based nanofibers allow improving specific functionalities in terms of cell recognition and molecular release. For instance, WK was combined with natural proteins including Gelatin or/and Sericin from Silk fibroin showing peculiar microscopic interactions among chains (i.e., decrease of hydrogen bonds of N–H groups) that beneficially influence in vitro interaction with cells [5]. Otherwise, WK was successfully combined with synthetic biodegradable polymers such as Polycaprolactone (PCL) [6] that confers high chemical stability to the nanofibres, overcoming some intrinsic limitations of proteins (i.e., mechanical properties), but preserving their innate biological functionalities. More recently, WK was also combined with water soluble polymers with hydrogel-like behaviour such as Polyvinilalcohol (PVA)[7] or Polyethylenglicole (PEG) [8] for the fabrication of a new generation of fibrous scaffolds based on the use of green processing routes towards a more sustainable approach in biomedical applications.