The purpose of a fluorescent marker, such as a fluorophore-conjugated antibody, is to directly target an epitope of interest and to allow its biological and biochemical properties to be measured.
Fluorescent markers are useful in a wide range of applications, including identifying and quantifying distinct populations of cells, cell surface receptors, or intracellular targets; cell sorting; immunophenotyping; calcium flux experiments; determining nucleic acid content; measuring enzyme activity; and apoptosis studies.
Several fluorophores can be excited by a single laser. By using filters it is possible to analyze several parameters of the sample at any one time. This forms the basis of multicolor fluorescence studies.