LUMINESCENT LANTHANIDE CHELATES - A WAY TO MORE SENSITIVE DIAGNOSTIC METHODS

The unique luminescence properties of certain lanthanides are valuable features in aiming at more sensitive label technologies for clinical diagnostic use. The use of these properties in bioanalytical assays requires development of specific chelate technologies for labelling, i.e. binding of the ion to bioaffinity reagents, carrying it through the assay procedure, creating the optimal environment for emission and so forth. So far the most successful lanthanide label technology is composed of sequential use of two different chelate systems: a bifunctional polyaminopolycarboxylate derivative used for labelling of bioaffinity reactants with the lanthanide ion and a beta-diketone-TOPO chelate optimized for time-resolved fluorometric determinations. This technology has achieved an established position as a highly sensitive method in in vitro clinical immunodiagnostics. Subsequently, a number of alternative approaches have been developed, including stable and highly luminescent chelates, which can be directly coupled to bioaffinity reactants to form luminescent tracers. These chelates are invaluable in studies aiming at sensitive and quantifiable localizations of analytes directly in situ, e.g. on tissue sections or cell surfaces.