Development of a chemiluminometric immunosensor array for on-site monitoring of genetically modified organisms

Genetically modified organisms (GMOs) have been mainly developed for mass production of agricultural plants; however, there are concerns that transgenic crops might cause side effects on ecosystems and human beings. Therefore, to quantitatively trace the genetically modified products, we constructed a chemiluminometric immunosensor array for the detection of recombinant marker proteins expressed in GMOs, i.e., 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), neomycin phosphotransferase II (NPT II), and phophinothricin acethyltransferase (PAT). Monoclonal and polyclonal antibodies specific to each marker were raised, and the specificities and immunoreactivities to the respective markers were characterized. The capture antibodies were immobilized on predetermined regions of a glass slide where the sandwich-type immunoassays were carried out. Photodiodes were located on the bottom of the slide in an aligned arrangement to the immobilized antibody sites such that the light signals resulting from the immunoassays could be detected in situ. Under optimal conditions, the immunosensors were able to detect 1% GMO marked with EPSPS, which was the minimum content over the total content, and 3% GMOs labeled with NPT II or PAT. The sensor array developed in this study would be useful for measuring a particular GMO in a specimen containing unidentified species.