A novel type of dual-lanthanide-complexs doped Ag@silica fluorescent nanoparticles with amino functionalized has been developed by a facil water-in-oil (W/O) microemulsion method. The structural and optical properties of the nanoparticles were characterized by transmission electron microscopy (TEM), fluorescence spectra and UV-Vis spectra, respectively. The results show that the fabricated nanoparticles are spherical, core-shell structure, highly fluorescent and highly photostable. Measurements of the luminescent emissions from the Ag@SiO₂ nanoparticles, in comparison with control silica nanoparticles without silver cores, showed that the presence of the silver cores can increase the fluorescence intensity approximately 3-fold. This enhancement offers a potential increase in detection sensitivity with increased photostability. The nanoparticles are expected to be utilized in super-sensitive bioassays systems such as time-resolved fluorescence immunoassay, biosensor and biochip.

Key words: Eu^3＋/Tb^3＋-PABA-DTPA-APTMS, Eu^3＋, Tb^3＋, Ag@SiO₂ nanoparticles, metal enhancing fluorescence