Abstract
Dentin is a natural extracellular matrix, but its availability in bone grafting and tissue engineering applications is underestimated due to a lack of proper treatment. In this study, the concept of extrafibrillar demineralization is introduced into the construction of dentin-derived biomaterials for bone regeneration for the first time. Calcium chelating agents with large molecular weights are used to selectively remove the extrafibrillar apatite minerals without disturbing the intrafibrillar minerals within dentin collagen, resulting in the formation of an extrafibrillarly demineralized dentin matrix (EDM). EDM with distinctive nanotopography and bone-like mechanical properties is found to significantly promote cell adhesion, migration, and osteogenic differentiation in vitro while enhancing in vivo bone healing of rat calvarial defects. The outstanding osteogenic performance of EDM is further confirmed to be related to the activation of the focal adhesion-cytoskeleton-nucleus mechanotransduction axis. Overall, this study shows that extrafibrillar demineralization of dentin has great potential to produce hierarchical collagen-based scaffolds for bone regeneration, and this facile top-down fabrication method brings about new ideas for the biomedical application of naturally derived bioactive materials.