Fuzzy liquid analysis by an array of nonspecifically interacting reagents: the taste of fluorescence.

Complex or unknown liquid analysis requires extensive instrumentation and laboratory work; simple field devices usually have serious limitations in functionality, sensitivity, and applicability. This communication presents a novel, effective, and simple approach to fingerprinting liquids. The method is based on nonspecific interactions of the sample liquid, a long lifetime luminescent europium label, and various surface modulators in an array form that is readily converted to a field analysis µTAS system. As compared to existing e-nose or e-tongue techniques, the method is unique both in terms of sensitivity and usability, mainly due to the well-known unique properties of the europium label. This communication demonstrates the use of this new method in distinguishing different wines, waters, alcohols, and artificially modified berry juices.

Cell-based beta2-adrenergic receptor-ligand binding assay using synthesized europium-labeled ligands and time-resolved fluorescence.

High-sensitivity, high-throughput, and user-friendly lanthanide-based assays for receptor-ligand interactions provide an attractive alternative to the traditional radioligand displacement assays. In this study, three small-molecule pindolol ligand derivatives were synthesized and their binding properties were tested in a radioligand displacement assay. The ligand derivatives were further labeled with fluorescent europium(III) chelate for beta(2)-adrenergic receptor-ligand binding assay. The europium-labeled pindolol ligands having no spacer (C0) or a 12-carbon spacer (C12) arm bound to the human beta(2)-adrenergic receptors overexpressed in human embryonic kidney HEK293(i) cells. Europium ligand with a 6-carbon spacer arm (C6) showed no binding. Competitive binding assays were developed with the functional labeled ligands. The IC(50) values for beta(2)-adrenergic antagonist propranolol were 60 and 37 nM, the Z' values were 0.51 and 0.77, and the signal-to-background ratios were 5.5 and 16.0 for C0 and C12, respectively. This study shows that functional time-resolved fluorescent assays can be constructed using fluorescent lanthanide chelates conjugated to small-molecule ligands.