Development of hydroxyapatite nanorods-polycaprolactone composites and scaffolds derived from a novel in-situ sol-gel process

Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which displays splendid biocompatibility and bioactivity properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL) was employed as a matrix and hydroxyapatite nanorods were used as a reinforcement element of the composite. HA/PCL nanocomposites were synthesized by a new in-situ sol-gel process using low cost chemicals. Chemical and physical characteristics of the nanocomposite were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FTIR) analyses. XRD analysis revealed that pure hydroxyapatite with no undesirable compound was formed within the nanocomposite. Moreover, hydroxyapatite had low crystallinity with the average crystallite size of 62.5 nm. FE-SEM images showed dispersion of HA nanorods in PCL matrix with suitable interaction were obtained. The average length and diameter of HA nanorods were calculated 167 nm and 53 nm, respectively. It was found that HA/PCL nanocomposite had marcoporous structure and high surface area which are essential parameters for cell attachment and protein absorption. Biological properties of HA/PCL scaffolds, prepared through a solvent casting process, were investigated under in vitro condition. Bioactivity of these scaffolds was studied in a saturated simulated body fluid (5×SBF). It was confirmed that HA/PCL scaffold was uniformly covered with a layer of calcium phosphate crystals with the thickness of few microns and phase composition of hydroxyapatite. Consequently, scaffolds met the requirements of materials for bone tissue engineering and could be used for many clinical applications in orthopedic and maxillofacial surgery.