FPIA Technology IMx TT4
Sample, pretreatment solution, T4 antibody, and buffer are delivered to the predilution well of the FPIA sample cartridge. The pretreatment solution displaces T4 from protein binding sites.
Variable unbound T4 from the sample equilibrates with the fixed amount of antibody. If the concentration of the T4 in the sample is high, less antibody sites remain open.
An aliquot of the predilution mixture is equilibrated with T4 Fluorescein Tracer in the FPIA cuvette. T4 Tracer binds to open T4 sites on the T4 antibody.
When excited by polarized vertical light, the small unbound T4 Tracer molecule rotates rapidly, emitting light in many different planes. The result is a decrease in the intensity of vertical polarized light.
In contrast to unbound T4 Tracer, antibody complexes of sample T4 and T4 Tracer are large molecules. Large molecules rotate slower and emit polarized light in the same vertical plane. The result is an increase in the intensity of the vertical polarized light.
FPIA optics detect and measure the intensity of the polarized, vertical light. The change in polarized light intensity is proportional to the concentration of the T4 in the specimen.
