Abstract:
This study aimed to develop bone scaffold from in situ-forming hydrogel of Thai silk fibroin (SF) and collagen. SF solution was sterilely produced and induced to form gel by oleic acid and poloxamer-188 surfactant combinations with different HLB values. Effect of different HLB values of surfactants on gelation time and physicochemical properties of induced 4 wt% SF with/without 0.1 wt% collagen was studied. Shorter gelation time could be achieved by induction with lower HLB surfactants. SF and SF blended with collagen solution displayed negative charge with added surfactant between HLB1-20. Gel fraction measurement demonstrated inverse relationship between HLB value of surfactants and SF hydrogel stability. There was a trend showing an increase in water absorption capacity of SF with collagen hydrogel induced by surfactants with higher HLB values. Rheological studies revealed an optimum HLB value of surfactants to achieve maximum gel strength. Effect of collagen on modulus of hydrogels was also demonstrated. SEM micrographs showed typical interconnected microporous morphology of all hydrogels. An increase in HLB value of surfactants and addition of collagen resulted in larger pore size with less interporous connectivity and thicker cross-linking networks. DSC study demonstrated more complete crystallization in hydrogels induced by surfactants compared with non-induced hydrogels. There was a trend indicating higher thermal stability of hydrogels with increased HLB value of surfactants. FTIR results demonstrated higher beta-sheet structure in SF hydrogel induced by higher HLB value of surfactants. The presence of collagen precluded this effect. The gelation of SF hydrogels induced by lower HLB surfactant was resulted from interaction between SF and surfactants rather than conformational change to beta-sheet. In vitro cell culture verified the biocompatibility of SF and SF blended with collagen hydrogels with a potential to induce osteogenic differentiation of encapsulated rat’s MSC. However, added collagen promoted proliferation more than differentiation and induced matrix formation. In vivo study in rat demonstrated the biocompatibility and potential of SF/collagen hydrogel as a scaffold and carrier for cell and growth factor for bone regeneration.
