Biomimetic hydroxyapatite and strontium-doped derivatives from crab shells and their ingenious scaffold fabrication for bone tissue engineering

Abstract

The success of the most commonly used bio-ceramics in current medicine, hydroxyapatite (HAp), is due to its similar chemical and structural properties with the human bone tissue. The current research aims to calcine crab shells, a bio-waste source, to synthesize HAp, and dope it with strontium (Sr) to use it as a sustainable and economical source for bone tissue engineering. Different temperatures (900°, 1000°, and 1100 °C) were used for the calcination process. FE-SEM analysis showed the importance of temperature for morphology. The variance in the Ca/P ratio was revealed by EDX analysis. The higher the calcination temperature, the more pronounced were the peaks of HAp and (β-Tricalcium Phosphate) β-TCP were revealed by X-Ray Diffraction (XRD) analysis. Moreover, as the concentration of Sr2+ increased, both the crystallite size and crystallinity index (CI) of HAp decreased, as confirmed by XRD analysis. ATR-FTIR analysis showed the best-defined bond types (O-H, P-O, etc.). TGA and DSC analysis revealed the loss of adsorbed water and the appearance of endothermic peaks, respectively. To create a possible bone transplant substitute, scaffolds from HAp and strontium-doped HAp (Sr-HAp) were prepared utilising the foam replica method. At a Sr2+ doping of 1% (w/w) and a calcination temperature of 1100 °C, the highest percent cell viability was obtained, as determined by the MTT test. These results indicate that the concentration of the dopant (Sr2+) have a significant influence on the properties of the final material suitable for bone regeneration in situ.