Question

How are the reagents/antibodies placed inside a pregnancy test (please be practical and in detail), explain how the antibodies stay within the strip

Answer 1

Human chorionic gonadotropin(hcg) is a hormone present in the urine of pregnant woman. It is produced by placenta just after pregnancy to the pregnancy. The pregnancy test methods/kit/stripes use a membrane that contains all the necessary antibodies and reagents to perform the test. With the pregnancy test kit all the instructions are given to how to load the sample to the kit for the test. Once sample is loaded, sample starts migrating along with the membrane by the capillary action and encounters a monoclonal anti-hcg antibodies. If the sample contains hcg, a complex is formed with anti - hcg antibody and migrates continuously until the T- line region comes where it binds with a fixed polyclonal anti hcg antibody. It gives a different colour if the hcg level is 25mIU/mL or greater in the sample. If hcg is not in the sample then unbound monoclonal anti hcg migrates to the Control line where it binds with a different fixed polyclonal anti hcg and give colour regardless to the amount of hcg in the sample. In this way we get the results of the pregnancy test.

Sample is loaded generally morning time with the few drops of urine at the indicated place on the strip. All the necessary instructions are given on the pregnancy test kit packet. In this way we place antibodies within the strip.