Abstract
The use of polymer additives that stabilize fluidic amorphous calcium phosphate is key to obtaining intrafibrillar mineralization of collagen in vitro. On the other hand, this biomimetic approach inhibits the nucleation of mineral crystals in unconfined extrafibrillar spaces, that is, extrafibrillar mineralization. The extrafibrillar mineral content is a significant feature to replicate from hard connective tissues such as bone and dentin as it contributes to the final microarchitecture and mechanical stiffness of the biomineral composite. Herein, we report a straightforward route to produce densely mineralized collagenous composites via a surface-directed process devoid of the aid of polymer additives. Simulated body fluid (1×) is employed as a biomimetic crystallizing medium, following a preloading procedure on the collagen surface to quickly generate the amorphous precursor species required to initiate matrix mineralization. This approach consistently leads to the formation of extrafibrillar bioactive minerals in bulk collagen scaffolds, which may offer an advantage in the production of osteoconductive collagen-apatite materials for tissue engineering and repair purposes.