No abstract

The synthesis and luminescence properties are reported for 20 different chelates composed of 2,2':6',2"-terpyridine as the energy-absorbing and donating group, Eu"' and Tb"' as the emitting ions, methylenenitrilo(acetic acids) as the stable chelate-forming moieties, and isothiocyanato or (4,6-dichloro-1,3,5-triazin-2-yl)amino groups as the activated moieties for coupling to biomolecules.Introduction. -Time-resolved fluorometry combined with long-lifetime emitting lanthanide chelate labels provides an excellent way of creating highly sensitive label technologies for bioaffinity assays [ 11. A technology based on dissociative fluorescence enhancement [2], Devia@, has gained wide applications in the field of clinical diagnostics in immunoassays [3] and recently also in DNA hybridization assays [4]. In spite of the high sensitivity obtained, the Devia-type of technology is not suited for all applications, such as fluorescence imaging, immunohistochemistry, or in situ hybridization, because after ion dissociation it does not produce spatial information. To use luminescent lanthanide chelates also in in situ assays, new chelate labels need to be developed combining

Two different kinds of europium(III) chelates, luminescent and nonluminescent, were prepared. The chelates were coupled to bioanalytical reagents, such as antibodies, after activations of the amino group on the chelates with thiophosgene,2,4,6-trichloro-1,3,5-triazine, or iodoacetic anhydride. The reactivities of the activated luminescent chelates in the labeling of antibodies as well as the effects of both the coupling ratio and the linkage group to the luminescence quantum yield of the antibody-bound chelate were studied in aqueous buffer solution.

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 approximately 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 lanthanides-including a wide Stokes shift, a narrow emission peak, and long fluorescence lifetime-were 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 lanthanide chelate labels. The applicability of the labels prepared was demonstrated by a heterogeneous sandwich-type immunoassay for human prostate-specific antigen, where the lowest limits of detection of 1.6, 2.4, 10.1, and 114.2 ng/L were achieved using europium(III), terbium(III), samarium(III), and dysprosium(III) nanoparticles, respectively. The spectral and functional properties of the lanthanide-embedded polystyrene nanoparticles developed here suggest that the technology is applicable for high-sensitivity multicolor assays.