Biomimetic Synthesis of Collagen/Nano-Hydroxyapitate Scaffold for Tissue Engineering

This paper reports a precipitation method for the fabrication of compositionally graded biomimetic collagen/nano-hydroxyapatite (HA) composite scaffold. The method is centrifugation based and produce the precipitation of nano-HA crystallites in situ (calcium ions (Ca2+) react phosphate ions (PO43−) and precipitate a non-stoichiometric hydroxyapatite). It was observed that prism needle-like nano-HA crystallites (about 2.5 nm × 3 nm× 25 nm) precipitated on collagen fibrils in the interior of collagen matrix. Chemical and microstructure analysis revealed a gradient of the Ca to P ratio across the width of the scaffold, lead to the formation of a HA-rich side and a HA-deplete side of scaffold. The HA-rich side featured low porosity and agglomerates of the nano-HA crystallites; while HA-depleted side featured higher porosity and nano-HA crystallites integrated with collagen fibrils to form a porous network structure.