High brightness red emitting polymer beads for immunoassays: Comparison between trifluoroacetylacetonates of Europium.

Efficiently luminescing spherical polymer particles (beads) in the nanoscale regime of up to approximately 250 nm have become very valuable tools in bioanalytical assays. Eu- complexes imbedded in polymethacrylate and polystyrene in particular proved to be extraordinarily useful in sensitive immunochemical and multi-analyte assays, and histo- and cytochemistry. Their obvious advantages derive from both, the possibility to realize very high ratios of emitter complexes to target molecules, and the intrinsically long decay times of the Eu-complexes, which allows an almost complete discrimination against bothersome autofluorescence via time-gated measuring techniques; the narrow line emission in conjunction with large apparent Stokes shifts are additional benefits with regard to spectral separation of excitation and emission with optical filters.