Organoapatite growth on an orthopedic alloy surface

We report here a method to coat orthopedic metals with the artificial bone material organoapatite. The growth of organoapatite on titanium alloy surfaces of foils and porous cylinders involves sequential preadsorption of poly(L-lysine) and poly(L-glutamic acid) on metal, followed by exposure to organoapatite-precipitating solutions. The organoapatite characterization of the coating was carried out by transmission electron microscopy, electron diffraction, scanning electron microscopy, energy-dispersive X-ray scattering, powder X-ray diffraction, FT-IR, and elemental analysis. The preadsorbed poly(amino acids) in the form of a self-assembled bilayer of oppositely charged macromolecules can lead to a surface coverage of titanium alloy in the range of 70-90%. The deposition mechanisms could involve the surface capture of embryonic crystals and the nucleation of apatite on the bilayer. Bioabsorbable organoapatite could serve as a tissue-engineering scaffold for bone regeneration into porous implants.