Bio-inspired synthesis of hydroxyapatite materials from two natural sources: a crack behavior and biological insight

Many natural systems more often than not exploit some intricate structures to meet up with functionalities that surpass those sourced from man-made origin. So, elucidating how these biological systems attain mechanical functionalities is crucial to establishing a sustainable route for the production of naturally derived scaffolding materials. In this contribution, variants of hydroxyapatite (HAp)-derived scaffolds characterized by different unique morphologies were fabricated through direct mechano-chemical conversion of catfish and non-separated animal bones by the regulation of reaction temperatures. The representative scaffolds were prepared by cold compaction and sintered at 900, 1000, and 1100 °C. The fabricated scaffolds produced distinct crystal morphologies with a composite of micro- and nano-dimensional structures in the shape of rods and flowers. Energy dispersive spectroscopy (EDS) analysis was used to estimate the calcium-to-phosphate ratios, while acoustic emission was used to detect the crack propagation behavior of the scaffolds. Porosity evaluation was conducted, while the antimicrobial properties of comparatively better scaffolds were investigated using the disc diffusion method. The obtained experimental results showed that at 900 °C, optimum properties were obtained with a Ca/P ratio of 1.53 for the CB-900 sample representing a calcium-deficient scaffold with potential tissue engineering applications. The crack propagation data showed relatively lowest activity for the CB-900 sample with notable activity for two bacterial strains.