Self-assembled collagen/hydroxyapatite composite materials

The purpose of this study is the preparation and characterization of highly oriented collagen/hydroxyapatite (COLL/HA) composite materials, through a self-assembling method, starting from collagen gel and hydroxyapatite precursors by an in vitro modified mineralization method. Briefly, this method can be descript as follow: collagen gel (containing 3.21% collagen) is firstly let 24h in contact with Ca(OH)(2) suspension in order that Ca(2+) neutralize the COOH groups than, in the second stage, the corresponding NaH(2)PO(4) is added, in order to form HA. The synthesis of COLL/HA nanocomposite is performed under controlled experimental conditions: 37 degrees C. pH=9 and air drying. The morphology of the composite material is strongly influenced by the drying method, especially due to the drying time. If the freeze drying method is used the obtained material is highly porous, but no orientation can be observed. In air, the drying is slow enough so that the wet composite material can reorganize and become uniaxial oriented. Our results prove that in certain conditions, oriented COLL/HA nanocomposites materials can be obtained, starting from collagen and hydroxyapatite precursors, through a very simple and accessible method. It is quite difficult to quantify the orientation degree of the composite, but, most of the fibres are uniaxialy oriented, the average orientation degree being 97.46%. The resulted composite materials were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Differential Thermal Analysis coupled with Thermal Gravimetry Analysis (DTA-TG), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). (c) 2010 Elsevier B.V. All rights reserved.