Photoluminescence of europium-activated hydroxyapatite nanoparticles in body fluids

Hydroxyapatite (Ca 10(PO 4) 6(OH) 2, HA) nanoparticles activated with Eu 3+ were synthesized using the sol-gel technique. The crystal structure was elucidated by X-ray diffraction analysis and the internal crystal structure and morphology was studied by transmission electron microscopy. Under excitation with 394 nm light, the powders are red-emitting. The photoluminescence bands are detected at 575 nm ( 5D 0→ 7F 0), ~590 nm ( 5D 0→ 7F 1), 613 nm ( 5D 0→ 7F 2) and 626 nm ( 5D 0→ 7F 2). The nanosized HA:Eu dispersed in urine and blood serum showed high stability with respect to their optical properties, although some transitions underwent a change in relative emission intensities. A change in emission intensities was also observed for the cysteine dispersion. The stability at different pHs was studied in water and body fluids. The HA:Eu nanoparticles are suitable as biomarkers for nanomedical applications. © 2012 by American Scientific Publishers