Silk fibroin-chitosan aerogel reinforced by nanofibers for enhanced osteogenic differentiation in MC3T3-E1 cells

Proper bone scaffolds should be biocompatible, mechanically robust and porous for cell migration. Here, pure silk fibroin (SF)-chitosan (CS) aerogel scaffolds reinforced with different amount of SF nanofibers (SF-CS/NF1%, SF-CS/NF2% and SF-CS/NF3%) are prepared for bone regeneration. Surface morphology and composition were analyzed to ensure successful integration of each component. Incorporating 3 % nanofibers endowed the aerogels with a resistance to 3.5 times the compressive stress of the pure SF-CS aerogels. The benefits of nanofibers were also confirmed by the high porosity of 72.3 +/- 1.3 %, the regulated pore size and the high-water uptake ratio of 1770.4 +/- 156.8 %. Enhanced cell viability of the aerogel scaffolds was verified with Cell Counting Kit-8 (CCK-8) assays, and confocal microscopy and scanning electron microscopy (SEM) images were taken to assess the cell migration and distribution. The cell differentiation on the aerogel scaffolds was evaluated with enzyme-linked immunosorbent assay (ELISA). Significantly higher level of Collagen type I (Col-I), osteocalcin (OCN), osteo-pontin (OPN), and alkaline phosphatase (ALP) expression was observed on SF-CS/NF3% aerogels. This biocom-patible nanofiber-reinforced aerogel scaffold facilitates osteogenic differentiation by rougher surface, enhanced mechanical strength and well-regulated pores. Thus, as-prepared scaffolds may be further applied in bone regeneration field.

Automated summary

Prepared silk fibroin-chitosan aerogel scaffolds reinforced with silk fibroin nanofibers exhibit biocompatibility, mechanical robustness, and porous structure, making them suitable for cell migration and bone regeneration. The addition of nanofibers enhances the compressive stress resistance, porosity, and water uptake ratio of the aerogels. Cell viability and migration are improved on the nanofiber-reinforced scaffolds. Enzyme-linked immunosorbent assay shows that the scaffolds promote osteogenic differentiation.