Flow cytometric competitive binding assay for determination of actinomycin-D concentrations

Abstract
A single step, separation free competitive binding reaction between the fluorescent antibiotic mithramycin and actinomycin-D for common binding sites on DNA coated 10 μm diameter microspheres is described. The fluorescence of the microspheres is measured with a flowcytometer. In the presence of a constant amount of mithramycin, the microsphere fluorescence is inversely proportional to actinomycin-D concentration.