Nano/micro-formulations of keratin in biocomposites, wound healing and drug delivery systems; recent advances in biomedical applications

Keratin, a bio-sourced polymer of high sulfur content, reckons as the major component of the feather, hair, hooves, horns, and wool. Keratin-based formulations (KFs) have drawn great academic interest due to their intrinsic biofunctionality and high biocompatibility. KFs have been widely utilized in different fields, e. g., drug delivery, wound healing, tissue engineering, etc. Besides pure KFs, the blend systems of keratin and other (bio) polymers, as novel keratinous formulations, have started to trigger great interest, in recent years. In this study, an overview of the structure, features, extraction methods, and recent advances related to the application of KFs for various areas is provided. Furthermore, an overview of different KFs (e. g., 3-D scaffolds, films, fibers, and even hydrogels) and keratin blended with natural/synthetic polymers are discussed.