Synthesis, Characterization, and Application of Eu(III), Tb(III), Sm(III), and Dy(III) Lanthanide Chelate Nanoparticle Labels

Preparation and characterization of europium(III), terbium(III), samarium(III), and dysprosium(III) polystyrene nanoparticle labels with lanthanide-specific fluorescence properties has been presented. Emulsion copolymerization of styrene and acrylic acid was used to synthesize uniform-sized nanoparticles ∼45 nm in diameter. Europium(III) and samarium(III) lanthanides were chelated with 2-naphthoyltrifluoroacetone and trioctylphosphine oxide to dye the spherical particles, whereas terbium(III) and dysprosium(III) chelate complexes contained a newly synthesized ligand, 4-(2,4,6-tridecyloxyphenyl)pyridine-2,6-dicarboxylic acid. The fluorescence properties of the four lanthanidesincluding a wide Stokes shift, a narrow emission peak, and long fluorescence lifetimewere retained despite the incorporation into the nanoparticles. Furthermore, the nanoparticles, containing more than 1000 lanthanide chelates, were detectable at label concentrations 3 orders of magnitude lower than the corresponding soluble lanthanid...