Synthesis of luminescent bioapatite nanoparticles for utilization as a biological probe

A europium-doped apatitic calcium phosphate was synthesized at low temperature (37°C) in water–ethanol medium. This apatite was calcium-deficient, rich in hydrogen phosphate ions, and poorly crystallized with nanometric sized crystallites. It is similar to the mineral part of calcified tissues of living beings and is thus a biomimetic material. The substitution limit of Eu³⁺ for Ca²⁺ ions in this type of bioapatite ranged about 2–3%. The substitution at this temperature was facilitated by vacancies in the calcium-deficient apatite structure. As the luminescence of europium is photostable, the doped apatite could be employed as a biological probe. Internalization of these nanoparticles by human pancreatic cells in culture was observed by luminescence confocal microscopy.