Magnetic silk fibroin e-gel scaffolds for bone tissue engineering applications

Recently, the incorporation of magnetic nanoparticles into standard scaffolds has emerged as a promising approach for tissue engineering applications. This strategy can promote not only tissue regeneration but also reloading of scaffolds through an external supervising center that adsorbs growth factors, preserving their stability and biological activity. In this study, novel magnetic silk fibroin e-gel scaffolds were prepared by the electrogelation process of concentrated Bombyx mori silk fibroin (8 wt%) aqueous solution. In addition, basic fibroblast growth factor was conjugated physically to human serum albumin=Fe3O4 nanoparticles (71.52 +/- 2.3nm in size) with 97.5% binding yield. Scanning electron microscopy images of the prepared human serum albumin=Fe3O4-basic fibroblast growth factor-loaded silk fibroin e-gel scaffolds showed a three-dimensional porous morphology. In terms of water uptake, basic fibroblast growth factor-conjugated scaffolds had the highest water absorbability among all groups. In vitro cell culture studies showed that both the human serum albumin coating of Fe3O4 nanoparticle surface and basic fibroblast growth factor conjugation had an inductive effect on cell viability. One of the most used markers of bone formation and osteoblast differentiation is alkaline phosphatase activity; human serum albumin=Fe3O4-basic fibroblast growth factor-loaded silk fibroin e-gels showed significantly enhanced alkaline phosphatase activity (p<0.05). SaOS-2 cells cultured on human serum albumin=Fe3O4-basic fibroblast growth factor-loaded silk fibroin e-gels deposited more calcium compared with those cultured on bare silk fibroin e-gels. These results indicated that the proposed e-gel scaffolds are valuable candidates for magnetic guiding in bone tissue regeneration, and they will present new perspectives for magnetic field application in regenerative medicine.