The antibodies specific to Cry1Ab and CP4EPSPS are immobilized on the nitrocellulose membrane as two different test lines. An anti-mouse IgG is immobilized as control line. Second antibody specific for each Cry1Ab and CP4EPSPS is conjugated with colloidal gold and is incorporated in the sample area of lateral flow strip.
When the LFS is placed in the corn seed or leaf extract, the Cry1Ab or CP4EPSPS proteins, if present in the sample extract bind to the corresponding antibody labelled with gold nano particles and the complex moves upward by capillary action. The complex then binds to the antibody coated on the membrane as two different test lines resulting in pink/purple color test lines. As the complex moves further up, it binds to the control line resulting in pink/purple color control line. In the absence of protein in sample extract (Cry1Ab or CP4), the corresponding test line does not appear. Control line always appears in pink/purple color indicating validity of the test protocol.