Biomimetic bilayer scaffold from Bombyx mori silk materials for small diameter vascular applications in tissue engineering

Abstract

Enhancing the biocompatibility and mechanical stability of small diameter vascularscaffolds remain significant challenges. To address this challenge, small-diametertubular structures were electrospun from silk fibroin (SF) from silk textile industry dis-carded materials to generate bilayer scaffolds that mimic native blood vessels, butderived from a sustainable natural material resource. The inner layer was obtained bydirectly dissolving SF in formic acid, while the middle layer (SF-M) was achievedthrough aqueous concentration of the protein. Structural and biological properties ofeach layer as well as the bilayer were evaluated. The inner layer exhibited nano-scalefiber diameters and 57.9% crystallinity, and degradation rates comparable with theSF-M layer. The middle layer displayed micrometer-scale fibers diameters with anultimate extension of about 274%. Both layers presented contact angles suitable forcell growth and cytocompatibility, while the bilayer material displayed an intermedi-ate mechanical response and a reduced enzymatic degradation rate when comparedto each individual layer. The bilayer material emulates many of the characteristics ofnative small-diameter vessels, thereby suggesting further studies towards in vivo opportunities.