This bifuctional biotin derivative is used for spectrophotometric determination of biotinylation degree. The assay
is based on the kinetic analysis of the enhancement of fluorescence of streptavidin/fluorescein biotin complexes
in the presence of biotin. The fluorescence enhancement of fluorescein biotin is proportional to the concentration
of biotin. Because the assay is amenable for use in small volumes of 5-50 uL or bead-based assays, the detection
limits can be extended to the femtomole range. The dynamic aspects allow the assay to be used for a broader
range of applications including its use as an indicator for laminar-flow assays carried out in microfluidic device