Fluorescence Polarization Immunoassay (FPIA) is a type of immunoassay that utilizes fluorescence polarization to detect and quantify the presence of specific substances in a sample. It is a highly sensitive and specific method commonly used in medical diagnostics and research.
In FPIA, a fluorescently-labeled molecule called a tracer is used in conjunction with an antibody that specifically binds to the target substance. The fluorescein molecule emits polarized light when excited by a certain wavelength of light. When the target substance is present in the sample, it competes with the labeled tracer for binding to the antibody. This competition causes a change in the rotation of the tracer when excited by polarized light, resulting in a change in fluorescence polarization.
Fluorescence polarization is measured by determining the degree of randomization of the polarized light emitted by the tracer. The degree of polarization is inversely proportional to the binding of the target substance to the antibody. By measuring the changes in fluorescence polarization, the concentration of the target substance in the sample can be quantified.
FPIA offers several advantages over other immunoassay methods. It is a homogeneous assay, meaning that separation steps are not required, making it faster and less complex. The high sensitivity and specificity of FPIA allow for accurate and precise measurements. It is also applicable to a wide range of target substances, including small molecules, proteins, and hormones.
In summary, Fluorescence Polarization Immunoassay is a powerful analytical technique that uses measurement of changes in fluorescence polarization to detect and quantify specific substances in a sample. Its sensitivity, specificity, and versatility make it a valuable tool in fields such as clinical diagnostics and research.
