Rapid Detection Kit for FLAG-tagged Proteins (Competitive Assay)

The Rapid Detection Kit is used for quick, simple detection of FLAG-tagged proteins through a sensitive colloidal gold-based lateral flow immunoassay (LFIA). The LFIA strip is composed of membrane immobilized antibodies, sample pad, conjugate pad, and absorbent pad.
The gold conjugated monoclonal antibodies against FLAG-tag are immobilized at conjugate pad. The proteins with FLAG-tag are immobilized over test line. The secondary antibodies are immobilized at control zone. The sample is applied to the sample pad at one end of the strip and it subsequently migrates to the other parts of strip by capillary action. If the sample contains FLAG-tagged proteins, the sample together with the conjugated antibodies bound to these FLAG-tagged proteins, migrates along the strip into the detection zone. Thus, no or a small amount of gold-conjugated antibodies will bind to the FLAG-tagged protein antigens immobilized on the test line. Intensity of color at test line inversely corresponds to the concentration of FLAG-tagged proteins in the sample. In a sample where no FLAG-tagged proteins are present or the concentration of FLAG-tagged proteins is below detectable levels, the gold-conjugated capture antibodies will bind to the FLAG-tagged proteins embedded on the test line and form a red line. In both positive and negative tests, the gold-conjugated anti-Flag capture antibodies will bind to the secondary antibodies immobilized at the control line. A red control line will appear in both positive and negative results.
The recommended working range of the competitive lateral flow assay is 1 ug/ml to 10 ug/ml of purified FLAG-tagged proteins. The color of the test line is negatively related with the concentration of FLAG-tagged proteins in the sample. When the concentration of FLAG-tagged proteins in the sample reaches 1 ug/ml and above, the intensity of the test line will be effectively weakened, showing a light red band or no color. The lateral flow strip will continue to show positive results at concentrations greater than 30 ug/ml, visualized by complete loss of the test line.

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