Synergistic effect of sericin and keratin in gelatin based nanofibers for in vitro applications

This work evaluates the physico-chemical properties of electrospun nanofibers resulting from the combination of gelatin from bovine skin with keratin from wool and sericin from silk fibers to validate their use for in-vitro interaction studies. Gelatin is a natural protein obtained by partial hydrolysis of collagen. It is recognized that its use for the fabrication of bioinspired scaffolds is favorable due to peculiar biological properties, including bioactivity, biocompatibility, biodegradability, non-antigenicity, non-immunogenicity, non-toxicity and non-carcinogenicity. Keratin is a protein characterized by a high sulfur content found in different biomasses (wool, feathers, hairs, horns). Keratin is used to produce nanofibers, sponges, flexible films and fibers. Sericin is the protein that makes up 15-35% of the silk cocoons of the Bombyx mori silkworm with recently recognized properties in terms of biodegradability, antibactericity, cytocompatibility, UV resistance and antioxidant properties. We demonstrated that the presence of sericin influences the fiber morphology at the macroscopic level and affects the chemical and thermal behavior of electrospun nanofibers in comparison with gelatin-based ones. Moreover, we verified that sericin, in combination with keratin macromolecules, can amplify the biochemical signal of gelatin, improving the in-vitro stability of gelatin-based nanofibers. In vitro results confirm a synergistic effect of sericin and keratin on human Mesenchymal Stem Cells (hMSCs) proliferation associated with enhancing in-vitro stability directly ascribable to the peculiar physical interaction among the proteins. These findings suggest the use of sericin/keratin/gelatin-enriched electrospun fibers as nanostructured platforms for interface tissue engineering. Biocompatibility is investigated in terms of hMSCs proliferation at different days. CCK- 8 assay data showed cell growth after 3 days without significant differences among the different groups. A significant increase in cell proliferation is recorded in the case of GLKASR only after 7 days, thus confirming the synergic effect of sericin and keratin on hMSC response, respect to the other groups.