Microwave assisted synthesis of nano sized sulphate doped hydroxyapatite

Inorganic sulphate is required by all mammalian cells to function properly, it is the fourth most abundant anion in the human plasma. Sulphate ions are the major source of sulphur which is considered an important element for sustenance of life as it is present in the essential amino and is required by cells to function properly. In this study we have successfully substituted sulphate ions (SO42−) into hydroxyapatite (Ca10(PO4)6 − x(SO4)x(OH)2 − x) lattice via ion exchange process with phosphate group. Concentration of SO42− ions was varied between X = 0.05–0.5, using (Ca (NO3)2·4H2O), ((NH4)2HPO4) and (Na2SO4) as starting materials. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), showed that the substitution of SO42− ions into the lattice resulted in peak broadening and reduced peak height due to the amorphous nature and reduced crystallinity of the resulting HA powder. Transmission electron microscopy (TEM) and field emission electron microscopy (FESEM) analysis confirmed the formation of needle shaped particles of 41 nm size with homogenous and uniform distribution of element within the HA structure.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Phase pure nano-sized sulphur doped hydroxyapatite has been synthesized. ► TEM analysis confirmed formation of needle shaped structure. ► Lattice parameters and cell volume increased with increase in sulphate doping. ► Crystallite size decreased as sulphate content inside the structure increased. ► Degree of crystallinity decreased with increase in sulphate substitution.