Self-Standing Macroporous 3D Scaffold from Silk Sericin: Fabrication, Characterization, and In Vitro Bio-evaluation

Abstract

Three-dimensional (3D) scaffolds made of natural biopolymers that mimic the extracellular matrix provide a versatile platform for a wide range of biomedical applications. However, developing drug-eluting, mechanically stable, uniformly porous, and biodegradable scaffolds with high fluid-sorption capacity remains a significant challenge. Sericin protein, about 30 wt.% of the silk cocoon, is typically discarded as a waste by-product in the degumming wastewater of the textile industry, while it possesses several biological advantages. In this study, we present the preparation of a self-standing macroporous 3D scaffold entirely from sericin, using covalent crosslinking with 1,4-butanediol diglycidyl ether and methanol-induced physical crosslinking through the ice-templating strategy. The pore size of the scaffold varies from 64 μm to 108 μm, depending on the cross-linker concentration. These scaffolds exhibit excellent elasticity with an average Young’s modulus of 12 kPa, indicating the potential for soft tissue culture. Notably, the scaffolds show a high swelling ratio of up to 988, sorbing water 10 times its weight, and demonstrate considerable water retention for up to 24 hrs. The biodegradability of the sericin scaffold in the presence of a protease enzyme shows approximately 78% degradation over 30 days. Additionally, the porous scaffold can encapsulate antibacterial drugs such as vancomycin, and the release profile demonstrated an initial burst release of approximately 20% within the first hour, followed by a gradual release, reaching around 79% of the total encapsulated vancomycin after three days. In vitro biological studies, including MTT assay, DAPI staining, and Actin cytoskeleton staining with human foreskin fibroblasts (HFF-1) cells cultured in the scaffold, demonstrate excellent biocompatibility. Furthermore, the antibacterial activity against B. subtilis suggests that the vancomycin-loaded sericin scaffold could be a useful material for wound dressings. Hence, the fabricated 3D sericin scaffold has strong potential for controlled drug delivery and tissue regeneration, facilitating faster healing.