Keratin Additive for Cellular Adhesion in Transcutaneous Prosthetics

The dermal barrier is widely considered the body's first line of defense against most foreign bodies, protecting it from both moisture loss and bacterial invasion. However, when the skin is ruptured for long-term medical interventions (e.g., transcutaneous prosthetics), it is difficult to restore and maintain this protective barrier. Although there are no direct, biological examples of true transcutaneous features in the human body, similar phenomena can be observed in phalangeal nails. This study aims to investigate keratin, the primary component of fingernails, in its hydrolyzed form as an additive to induce cell adhesion in two representative scaffold types. Electrospun fibers and chitosan-gelatin cryogels-two well-characterized scaffolds used in dermal tissue engineering-were selected for this study as a fibrous and macroporous foundation. Both electrospun fibers and cryogels were fabricated with a range of keratin additive concentrations (0, 1, 3, 5, 7, and 10 wt/wt% and wt/v% for electrospun fibers and cryogels, respectively) and tested for surface properties, mechanical strength, biocompatibility, and material behavior. Overall, it was determined that hydrolyzed keratin had a positive effect on cell adhesion and proliferation but that high quantities of the keratin resulted in adverse effects on the scaffold properties. With dermal applications in mind, this study found that 5 and 7 wt/wt% keratin electrospun fibers possessed required cell counts, surface energies, tensile strength, and contact angle, all with consistent reproducibility. For the cryogels, 3 and 5 wt/v% keratin had the best combined performance, maintained structural integrity through swelling and porosity, and displayed minimal loss in compressive strength. Therefore, hydrolyzed keratin represents a promising additive for bothelectrospun fibers and cryogels in tissue engineering applications.