Silk Fibroin 3D Microparticle Scaffolds with Bioactive Ceramics: Chemical, Mechanical, and Osteoregenerative Characteristics

Abstract

Preparation of 3D scaffolds for bone tissue engineering (BTE) is a challenging task as it requires appropriate pore size and porosities, mechanical properties, and controlled bioerosion rate. The focus of this work is the fabrication of silk fibroin (SF) 3D microparticle scaffolds with the incorporation of hydroxyapatite (HA) and calcium sulfate (CaS) as bioceramics. Physicochemical characterization shows ≈30% filler loading and ≈40% optimum porosity with >100 μm pore size for these filled/unfilled scaffolds. Nanoindentation studies show improved Young's modulus at microparticle level with the incorporation of bioceramics. SF‐HA scaffolds showed three fold increase in Young's modulus, whereas SF‐CaS showed two fold increase. In vitro bioerosion study results in early bioerosion with SF‐CaS scaffold, whereas prolonged bioerosion with SF‐HA scaffold. In vitro osteoregenerative potential is analyzed by estimating alkaline phosphatase (ALP), bone morphogenetic protein‐2 (BMP‐2), and osteocalcin (OCN). SF CaS supports early stage differentiation while SF 50% HA predominantly supports late stage. The expression of TNF‐α suggests a reduced risk of immune rejection. This work, therefore, concludes that although SF supports bone tissue regeneration, the choice of bioceramic enhances the applicability in various clinical scenarios by providing a controlled bioerosion rate, tunable speed of osteoregeneration, and improved load bearing capacities.