Surface modification of Thai silk fibroin scaffolds with gelatin and chitooligosaccharide for enhanced osteogenic differentiation of bone marrow-derived mesenchymal stem cells.

In this study, the surface modification of silk fibroin (SF) scaffolds with gelatin/chitooligosaccharide (G/COS) blends using the reaction of glutaraldehyde (GA) was established. The effects of G/COS mixing ratio (100/0, 90/10, 80/20, and 70/30) and GA crosslinking concentration (0.05, 0.10, 0.15, and 0.20 vol %) on the properties of scaffolds were investigated. At 0.10-0.20 vol % GA, all G/COS blends could be successfully conjugated on the SF scaffolds, as confirmed by the percentage of weight increased and the presence of functional groups indicating SF, G, and COS from FTIR spectra. Pore size of SF scaffolds was around 570 μm with 92% porosity, however, the G/COS-conjugated SF scaffolds showed thickened pore's wall, smaller pore size (∼184-275 μm) and less porosity (∼81%), but increased density. This modified structure subsequently improved the compressive modulus of the G/COS-conjugated SF scaffolds. In terms of biological properties, the gelatin-conjugated SF scaffolds promoted the attachment and proliferation of bone marrow-derived mesenchymal stem cells (MSC) rather than the other scaffolds. However, the G/COS-conjugated SF scaffolds, particularly at the ratio of 70/30, promoted the osteogenic differentiation of MSC comparing to the SF scaffold, as confirmed by the production of alkaline phosphatase (ALP) activity and calcium (Ca), and the deposition of calcium phosphate (CaP). It was concluded that the G/COS-conjugated SF scaffolds showed great mechanical properties due to the β-structure of silk fibroin, as well as the enhanced biological properties due to the G/COS blends.