Preparation and Characterization of DPPDA-Eu3+ Doped Silica Fluorescent Nanoparticles

A new ligand of 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid (DPPDA) and Eu3+chelate compound of this ligand were prepared. Then DPPDA-Eu3+ doped silica fluorescent nanoparticles of DPPDA-Eu3+/SiO2 with primary amino groups on their surface were developed using a water-in-oil (W/O) microemulsion technique. Characterizations by transmission electron microscopy, fluorescent spectra, fluorescent molecules leaking experiments and photostable experiments show that the nanoparticles are spherical, monodisperse, and uniform in size(80±8 nm in diameter). The nanoparticles have high fluorescent signal and high photostability. When the nanoparticles were dispersed in aqueous solution with continuously ultrasound for 4h, no obvious leakage of fluorescent molecules was observed. As a novel fluorescent probe, the nanoparticle is expected to be applied in highly sensitive bioassays systems such as time-resolved fluorescence immunoassay, biosensor and biochip.