Characterization of collagen/hydroxyapatite composite sponges as a potential bone substitute

Hydroxyapatite and collagen composites (HAp/Col) have the potential in mimicking and replacing skeletal bones. Their combination should prove beneficial for bone tissue engineering due to their natural biological resemblance and properties. In this study, hydroxyapatite and collagen isolated from animal tendons were used in different proportions as composites. Sponges were prepared by freezing and lyophilization of corresponding composite solutions. The properties of composite sponges, such as microstructure, chemical and physical properties were studied. In the present investigation, a collagen sponge and a composite sponge made of composite of HAp/Col were prepared in our lab and characterized by attenuated total reflection Fourier transform infra-red spectroscopy, thermogravimetric analysis and scanning electron microscopy (SEM). Infrared spectroscopy (IR) in combination with attenuated total reflection (ATR) spectroscopy is one of the most widely used technique for surface infrared analysis. The ATR-IR analysis did not indicate shift of the band corresponding to -COO(-) for none of the used HAp/Col ratios. Thermogravimetric results suggested that collagen chains had been embedded with HAp to several complexes with different thermal stabilities. SEM was used to observe the morphology and pore size of the sponges. SEM observations showed the sponges of HAp/Col with fully interconnective macroporosity.