Synthesis and characterization of grafted nanohydroxyapatites using functionalized surface agents

Synthetic hydroxyapatite, HA [Ca-10(PO4)(6)(OH)(2)], is a bioactive material that is chemically similar to biological apatite, the mineral phase of bone (a nanocomposite material). Synthetic biocomposites, comprising a polymer and hydroxyapatite that are used for bone replacement, have limitations when loaded under fatigue in that the weak mechanical bond between the two phases can result in failure at the interface. Chemical coupling of the HA and polymer matrix may provide a means of improving the interfacial bonding between the polymer and HA phases. Herein, we report our first steps toward developing chemically coupled nano-biocomposites via a two-step process. We describe the synthesis and characterization of surface-grafted hydroxyapatite (SG-HA), which possesses a reactive C=C functional group. In future work, we will report on the second step, namely the coupling of this functional group to a polymer by a copolymerization reaction to give a chemically coupled nano-biocomposite. The SG-HA reported herein was characterized by a range of methods including P-31 and C-13 magic-angle spinning (MAS)-NMR, Fourier transform infrared (FTIR), and Raman spectroscopy.