Fabrication and characterization of biomimetic collagen–apatite scaffolds with tunable structures for bone tissue engineering

Abstract

The objective of the current study is to prepare a biomimetic collagen-apatite (Col-Ap) scaffold for improved bone repair and regeneration. A novel bottom-up approach has been developed, which combines a biomimetic self-assembly method with a controllable freeze casting technology. In this study, the mineralized collagen fibers were generated using a simple one-step co-precipitation method which involved collagen self-assembly and in situ apatite precipitation in a collagen-containing modified simulated body fluid (m-SBF). The precipitates were subjected to controllable freeze casting, forming scaffolds with either an isotropic equiaxed structure or a unidirectional lamellar structure. These scaffolds were comprised of collagen fibers and poorly crystalline bone-like carbonated apatite nanoparticles. The mineral content in the scaffold could be tailored in a range 0–54 wt% by simply adjusting the collagen content in the m-SBF. Further, the mechanisms of the formation of both the equiaxed and the lamellar scaffolds were investigated, and freezing regimes for equiaxed and lamellar solidification were established. Finally, bone forming capability of such prepared scaffolds was evaluated in vivo in a mouse calvarial defect model. It was confirmed that the scaffolds well support new bone formation.

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…A step further would be to perform the precipitation from the simulating solutions on templates of biomineralization proteins for the control of crystal organization and properties. For example, there are successful attempts to crystallize CaPO 4 on collagen to obtain bone-like composites (Nassif et al 2010;Li et al 2011;Xia et al 2012Xia et al , 2013Xia et al , 2014Antebi et al 2013). Such collagen/CaPO 4 biocomposites are currently under investigation for clinical use.…”

Reproducibility of ZrO2-based freeze casting for biomaterials

“…Given that the constituents and mechanical properties can be tailored, a common prospective application for these scaffolds and composites is mimetic bone [13][14][15][16]. While this application shows great promise, any biomedical implant material will need to undergo rigorous certification and testing.…”

Bone-Biomimetic Biomaterial and Cell Fate Determination

“…Collagen-apatite scaffolds consist of a collagen matrix mineralised with calcium phosphate crystals, giving a biomimetic system that resembles the composition of native bone matrix. These scaffolds were osteoinductive and showed ability to heal critical-sized defects in mouse calvaria and pig tibia over 4 weeks and 6 months, respectively (Pek et al 2008a;Xia et al 2013). More complex systems consisting of collagen combined with hydroxyapatite and a synthetic biocompatible polymer were able to encourage the attachment, proliferation and osteogenic activity of osteoprogenitor cells (Akkouch et al 2011;Liao et al 2004), as well as bridge a radial segmental defect in the rabbit over 12 weeks (Liao et al 2004).…”