Technology

The rapid assays developed by St. Paul Biotech are available in 3 formats:

Midstream-device		Cassette		Dipstick

Principal of the test

The Rapid tests developed by St. Paul Biotech all utilize the same lateral flow immunochromatographic technology.

Example: Pregnancy Test

The test uses two different antibodies hCG in sequence on the supporting membrane to detect any hCG present in the urine sample.

The first antibody to hCG is coated onto microscopic colloidal gold particles and placed within the conjugate pad. A second antibody to hCG is also fixed to the membrane in the region marked “T”. As the urine sample migrates through the absorbent reaction pack, the antibody-colloidal gold conjugate binds to hCG in the specimen forming an antigen/antibody/colloidal gold complex. This complex then continues to migrate along the membrane until it reaches region “T” which has fixed antibody to hCG. This fixed antibody binds to hCG in the antigen/antibody/colloidal gold complex causing it to accumulate at position “T” and form a visible pink-rose color band (positive result). If there is no hCG present the antibody labeled gold particles will not bind and accumulate, and no line will form in the test region (negative result).

Each test conjugate pad has also has excess gold particles present that will flow along the membrane until they reach the control zone “C” where they will accumulate to form a control line to show that the test is working properly.