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Colloidal gold immunochromatographic assay (GICA) is a recently developed immunochromatographic technique for the identification of molecules from fluid samples with several notable advantages, such as the lack of requirement for any sample pretreatment, low sample volume requirement, ease of operation, rapid turnaround time, low cost, no cross-reactions, and no equipment requirements. GICA is a lateral flow stick immunoassay that has become one of the most rapid and sensitive immunological detection methods, which is widely used in medical, biological and other fields.

The Principle of Colloidal Gold ImmunoChromatographic Assays used in GICA Kits

The basic principle of immunochromatography is highly similar to that of the ELISA sandwich method (either competitive or direct). The main difference is in that the immunological reaction is carried out on chromatographic paper by capillary action. For this system, two kinds of specific antibodies against a single antigen are used. One of the antibodies is immobilized on the chromatographic paper, and the other is labeled with colloidal gold and infiltrated into the sample pad.

Hydrogen tetrachloroaurate (III) hydrate (HAuCl4) can can form a gold particle under the effect of reductant (e.g., white phosphorus or ascorbicacid). Under the influence of electrostatic forces, it reaches a stable colloidal state, which is named Colloidal gold.

GICA Rapid Strip Tests

GICA (Gold Immunochromatography Assay) is a novel immunolabelling technique utilizing colloidal gold as the tracer. A specific antigen/antibody is fixed on a membrane. Also, a colloidal gold reagent containing a second polyclonal antibody or monoclonal antibody is absorbed on the conjugate pad. After being added to the sample pad, the liquid will move by capillary action and will dissolve and react with the colloidal gold labeling reagent. Once the sample-colloidal gold compound moves to the antigen/antibody region, it will specifically bind to the fixed antigen/antibody and be intercepted to accumulate on the detection region. Thus, a positive reaction will yield color )or no color for competitive assays) observable by naked eyes.

Hence, many GICA kits have been developed for rapid and convenient human diagnostics. Kits have been used for detection of human serum cardiac troponin Iheart-type fatty acid-binding protein (FABP) and Influenza Virus A Antigens and many others.

Finally, Elabscience has developed a wide selection of Rapid Test Kits based on GICA. Our GICAs kits can be used for detection of a wide diversity of targets for samples such as food, urine, serum, etc.. Elabscience GICA kits are aimed at providing solutions for food safety and animal disease detection.