Fluorescent Immunoassays (FIA)

Fluorescent Immunoassays are simply a different type of immunoassay. The key variable is the biochemical technique used for detecting the binding of the “detection” antibody and the analyte molecule. The advantages of a Fluorescent detection system have been known for many years. These include higher sensitivity detection of the analyte, simplified reagents and simpler assay designs. Several breakthroughs have occurred over the past few years that have enabled the implementation of a fluorescent based immunoassay system at the point of care.

A modern fluorescent based immunoassay uses as the detection reagent a fluorescent compound which absorbs light or energy (excitation energy) at a specific wavelength and then emits light or energy at a different wavelength. The difference between the wavelength of the excitation light and the emission light is called the Stokes shift. The greater the shift or difference in the wavelength the less interference there will be by having the excitation light detected as part of the emission light. Recently a number of technical improvements  have occurred that has enabled the implementation of a high sensitivity immunoassay system. These include the availability of narrow wavelength low cost light sources, newer more stable fluorophores that have very wide Stokes shifts, stable solid state light detectors and microprocessors to process and analyze the data from each test.

When a fluorescent detection system is linked to a lateral flow assay and matched with a powerful yet low cost analyzer like the Quidel Sofia or Sofia 2, the result is improved assay performance, the opportunity for walk away testing along with the elimination of misinterpretation often associated with visually-read point-of-care assays.