Synthesis and characterization of nanoapatites organofunctionalized with aminotriphosphonate agents

Organofunctionalized apatite nanoparticles were prepared using a one step process involving dissolution/precipitation of natural phosphate rock and covalent grafting of nitrilotris(methylene)triphosphonate (NTP). The synthesized materials were characterized by Brunauer–Emmett–Teller (BET) surface measurement, thermogravimetry, inductively coupled plasma emission spectroscopy (ICP–ES), elemental analysis, multinuclear solid state cross-polarization/magic angle spinning (CP/MAS) and single-pulse NMR spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDXA). After grafting BET measurements yielded particle specific surface areas ranging from 88 to 193 m2 g−1 depending on the grafted phosphonate. The results show that the surfaces of the nanoapatite particles can be covered with functional groups bound through a variable number of R–P–O–Ca bonds to render them organoapatites. - Graphical Abstract: Hydroxyapatite in the form of naturally occurring phosphate rock is converted in the presence of nitrilotris(methylene)triphosphonate (NTP) to high surface area apatite nanoparticles (dimensions measured by TEM) with NTP-functionalized surfaces. Highlights: ► Surface functionalized hydroxyapatite nanoparticles are prepared from natural phosphate rock in a one-step process. ► Covalent grafting of amine phosphonates to the nanoparticle surface is simultaneously accomplished by the presence of the organic molecules in the solution. ► Mesoporous particles of high surface area are created. ► Surface coverage is controlled by the concentration of amine phosphonate.