Immunoassays with time-resolved fluorescence spectroscopy: principles and applications.

This review deals with the application of time-resolved fluorescence spectroscopy in the field of immunoassay. The advantages of time-resolved fluorescence over conventional fluorometry are discussed and it is explained why the fluorescent lanthanide chelates, and especially the Eu3+ chelates, are the labels of choice in such applications. A brief description of commercially available time-resolved fluorometers is given. The principles of phase-resolved fluorometry are described. The relative merits and disadvantages of the two time-resolved assay principles currently available commercially are critically discussed. General assay designs by using either Eu3+ or a new Eu3+ chelate as the label are also discussed in some detail. A personal view of future trends in the field of immunoassay concludes this review.