Morphological and mechanical characterization of collagen-coated native silk fibroin fibers using chemical method

Native silk fibroin (SF) fibers have been widely studied and potentially used in tissue engineering scaffolds because of its robust mechanical properties. Onaccount that collagen is one of the main components in extra cellular matrix, coating collagen on the native SF fibers can improve the scaffold to behave both remarkable biocompatibility and excellent mechanical properties. However, there is lack of feasible methodology for coating collagen on the native SF fibers as well as evaluations of the morphological and mechanical characterizations for the bio-composite. In this paper we coated collagen on the native SF fibers by creating amide bonds between the carboxyls of the native SF and the amino groups of the collagen. The morphological and mechanical properties of the native SF and the collagen-coated SF fibers (under different collagen concentrations) were identified, including diameter, 3Droughness Sa, tensile propertieswith strain rate varying and stress relaxation properties. The results indicated that the chemical method could integrally coat collagen on the native SF fibers. All the diameter, roughness Sa, tensile and stress relaxation properties had no significant difference before and after the chemical modification of the native SF fibers. The collagen coating significantly increased fiber diameters, affected the tensile modulus of the fibers under different strain rates but insignificantly influenced roughness Sa and relaxation properties. In brief, the collagen-coated native SF fibers could provide robust tensile properties due to the native SF fibers and good biocompatible enviroment for cell adhesion due to the collagen coating.