Because the fluorescent secondary molecule is applied after capture of the free receptor from solution (Figure 2) the binding constants measured using a kinetic exclusion assay are for unmodified molecules in solution and thus more accurately reflects endogenous binding interactions than methods requiring modification (typically labeling or immobilization) before measurement. Kinetic exclusion assays have been performed using unpurified molecules, in serum, and have measured binding to cell membrane proteins on intact whole cell which brings the measured binding interactions closer to their endogenous state.
Molecules suited for measurement by KinExA are antibodies, recombinant proteins, small molecules, aptamers, lipids, nanobodies, and toxins.
Kinetic exclusion assay have also been applied for concentration immunoassay, where it has proven capable of providing the maximum theoretical, K limited, sensitivity. An example of this technique has been employed for sensitive detection of environmental contaminants i<nowiki/>n near real-time.