Development of porous chitosan-gelatin/hydroxyapatite composite scaffolds for hard tissue-engineering applications

Composite scaffolds prepared from natural polymers and hydroxyapatite (HA) are expected to have enhanced osteoconductive properties and as a result gained much attention in recent years for use in bone tissue-engineering applications. Although there are various natural polymers available for this purpose, chitosan (C) and gelatin (G) are commonly studied because of their inherent properties. The aim of this study was to prepare three-dimensional (3D) scaffolds using these two natural polymers and to add either non-sintered hydroxyapatite (nsHA) or sintered hydroxyapatite (sHA) to compare their influence on physical, chemical and mechanical properties of the scaffolds and on their affinities towards Saos-2 cells. For this purpose, nsHA and sHA were synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and particle size analyses. Then nsHA and sHA particles, with average sizes of 16 µm and 6 µm, respectively, were added to the solutions of C and G during the preparation step and the resultant 3D scaffolds were characterized. Compression tests indicated that presence of nsHA or sHA increased the Young's modulus and compressive strength of the scaffolds, and the values were very similar to those of human spongy bone. MTS assays, confocal microscopy and SEM analysis showed that cell attachment and proliferation were higher on C-G/sHA composite scaffolds compared to the other scaffolds. It was shown that the scaffolds prepared from chitosan, gelatin and HA are appropriate cell carriers for bone tissue engineering, especially those with sHA incorporated.