LUMINESCENT LANTHANIDE CHELATES LABELS FOR IMMUNOASSAYS

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Radiation hazards, limited shelf life, and costs have led to the development of non-isotopic labels for immunoassays. The alternate populate methods include enzyme immunoassay, chemiluminescence assay, and fluorimmunometric assay. Time-resolved fluorometry enables assays using lanthanide labels are comparable to those achieved by radioimmunoassays. The primary disadvantage of the lanthanide-based detection of bioanalytes has been the quenching of lanthanide luminescence in aqueous buffers. This problem has been addressed in commercial time-resolved fluoroimmunometric assay kits by adding an enhancement step before the luminescence measurement. To eliminate the enhancement step and speed up the immunoassays, a new class of metal chelator is proposed. This multidentate bifunctional chelating agent with covalently attached sensitizer is expected to give stable and luminescent lanthanide labels. The sensitivity of the new labels can further be improved using enzymes and labeled globulins. The new chelator will also help to incorporate a variety of labels, e.g., redox, fluorescent, and isotopic, onto various biomolecules for diverse end uses. Besides immunoassays, this technology will open new areas of research and lead to applications in a variety of fields, such as DNA hybridization assay, flow-cytometry, and time-resolved fluorescence microscopy. PROPOSED COMMERCIAL APPLICATION: Although non-isotopic labels, such as enzymes, chemiluminescent, and biotin, are used in immunoassays, improved sensitivity and specificity are often desirable. T he proposed luminescent lanthanide labels will permit sensitive detection of bioanalytes using time-resolved fluorometry in fewer steps than the commercially available kits. Secondly, simultaneous detection of bioanalytes using time-revolved fluorometry in fewer steps than the commercially available kits. Secondly, simultaneous detection of different bianalytes, which has been difficult with other techniques, will also be possible with the new reagents. Besides fluoroimmunometric assays, other potential applications include, flow cytometry, time-resolved fluorescence microscopy, and in situ DNA hybridization.