Functionalized Europium Oxide Nanoparticles Used as a Fluorescent Label in an Immunoassay for Atrazine

A method for simply and cheaply preparing inorganic phosphor nanoparticles of Eu2O3 as labels in biology has been demonstrated with a simple microwave-assisted surface chemistry. The capping process adds a silane layer to the surface of the particles and provides amine groups that can be used for biological conjugation. The surface layer also protects the particles during conjugation chemistry. The particles retain their desirable optical properties that are typical of europium, that is, a spectrally narrow, red emission and a long fluorescence lifetime. The application of the nanoparticle labels in an immunoassay yields very good sensitivity in an immunoassay for atrazine (sub-parts-per-billion detection limit) without optimization of the detection system. The microwave functionalization technique will permit a broad range of inorganic nanophase phosphors to be used in high-throughput assays for environmental monitoring.