Fabrication and characterization of bioinspired nanohydroxyapatite scaffolds with different porosities

Abstract

This study aimed to fabricate and characterize bovine nanohydroxyapatite (nano-HAp) scaffolds at a low sintering temperature. The compact bone/starch systems were formed using the inorganic matrix of trabecular bone powder and achira isolated starch. To generate the macroporosity, 0, 10, 15, and 20% achira starch granules were added. To obtain nano-HAp scaffolds, the compact bone/starch systems were incinerated at 600 °C, removing organic material. The scaffolds exhibit the presence of Ca, P, Sr, Ba, Fe, Na, Mg, K, and Si came from the HAp with a slight K increase because of the mineral contribution of the starch. Infrared spectroscopy helped determine the elimination of organic materials and evidenced carbonated nano-HAp. X-ray diffraction allows to determine the presence of nano-HAp crystals. Moreover, the X-ray tomography revealed an increased macroporosity (30–38%) for the scaffolds as the starch percentage increased and scanning electron microscopy (SEM) average pore length size for HAp, HAp-A10, HAp-A15, and HAp-A20 were 356.71 ± 156.71, 548.91 ± 131.99, 620.94 ± 147.93, and 728.16 ± 160.98 μm, respectively. In the same way, SEM images of the scaffolds evidenced the presence of micro and nano porosities. The N2 adsorption-desorption analysis corroborated the presence of mesoporosity with average pore diameters of 3.66 and 3.32 nm in the samples before and after the calcining process, respectively. Thus, thermal treatments did not significantly affect the mesoporous size. In addition, effective Young's modulus is governed by the intrinsic properties of HAp, while the porosity governs the plastic and breaking point. The coalescence phenomena create the scaffold macro architecture.