Tailoring the morphological features of sol-gel synthesized mesoporous hydroxyapatite using fatty acids as an organic modifier

Nowadays, owing to their large surface area, enhanced pore volume, increased porosity, and variable pore size, mesoporous materials, such as mesoporous silica and mesoporous carbon, have attracted significant attention in the areas of physical science and biomedical sciences. Due to their compositional and biological similarities to natural tissues, synthetic nanoscaled mesoporous hydroxyapatite (MPHA) nanoparticles possess good biocompatibility, bioactivity, and osteoconductivity and have recently expanded their applicability in a wide range of fields such as in tissue replacement, drug/ gene delivery carriers, and biocompatible coatings. In this study, we defined a novel route to synthesize mesoporous hydroxyapatite nanoparticles by the sol-gel method in the presence of stearic acid (SA), a biocompatible medium chain fatty acid that would function as an organic modifier. The as-prepared HAP particles were subjected to structural, functional and morphological characterization. Mesopores in HAP were observed for samples synthesized at pH 11 by removing the organic template. The porosity of HAP was confirmed by the Brunauer-Emmett-Teller (BET) analysis. The apatite deposition phenomenon in simulated body fluid at pH 7.4 confirms their in vitro bioactivity, and based on the in vitro cytotoxicity examined using Vero cell cultures, the as-prepared HAP particles exhibit excellent cytocompatibility and cell viability as high as 83% at an extract concentration as low as 25%. Moreover, the loading and leaching behavior of the drug in mesoporous HAP was studied using methionine (MT), an essential amino acid. These results confirm that nano mesoporous hydroxyapatite loaded with MT can be a potential aspirant as a biomaterial in biomedical applications.