Synthesis and in vitro biodegradability of carbonatedhydroxyapatite/chitosan composite spheres

Abstract

Hydroxyapatite(HAp)/biopolymer composites have been extensively applied as bone tissue regenerative materials because of their excellent biocompatibility and osteo-conductivity. However, the low biodegradability of HAp highly limited their practical applications. In this study, the carbonated hydroxyapatite(CHAp)/chitosan composite spheres with the size range of 100-200 μm and 300-400 μm were synthesized from CHAp and chitosan via a water/oil emulsion technique and their microstructure and biodegradability were evaluated. SEM observations showed that the resultant spheres were spherical in shape and had a rough surface. FT-IR spectrum showed that the composite spheres were derived from CHAp and chitosan due to the presence of the characteristic bands of phosphorous groups, carbonate groups and amide groups. XRD patterns showed that the composite spheres maintained the crystalline structure of CHAp crystals after combination of CHAp with chitosan. In vitro biodegradation was performed as the composite spheres were separately soaked in the buffer saline with the pH of 4.5 and 7.4. It was found that the biodegradation of the composite spheres was not affected by the size range of the composite spheres, but highly influenced by the pH value of the buffer saline. The composite spheres little degraded under the neutral condition, while around 25% of the composite spheres degraded after 7 days of incubation under acidic condition. Our results indicate that the present composite spheres are biodegradable and suitable as potential bone regenerative fillers.