An ultrasensitive label-free electrochemiluminescent immunosensor for measuring CrylAb level and genetically modified crops content

The development of genetically modified (GM) insect-resistant crops has aroused great public concern about the risks on the eco-environment resulting from a release of toxic Cry proteins (such as CrylAb) to the soil. Therefore, it is of crucial importance to measure the Cry proteins level and the GM crops content. Here, we have tested for the first time a method that uses novel carbon nanospheres (CNPs) label-free electrochemiluminescent (ECL) immunosensor for the ultrasensitive quantification of CrylAb and GM crops. In this work, novel CNPs were prepared from printer toner with a very facile approach, and linked with anti-CrylAb antibodies to modify a golden working electrode. The immunoreaction between CrylAb and its antibody formed an immunocomplex on the bioreceptor region of the sensor, which inhibited electron transfer between the electrode surface and the ECL substance, leading to a decrease of ECL response. Under the optimal conditions, the fabricated label-free ECL immunosensor determined CrylAb down to 3.0 pg mL(-1) within a linear range of 0.010-1.0 ng mL(-1), showing significant improvement of sensitivity than that of most previous reports. Meanwhile, the proposed method was successfully applied for GM rice BT63 and GM maize MON810 detections down to 0.010% and 0.020%, respectively. Due to its outstanding advantages such as high sensitivity, ideal selectivity, simple fabrication, rapid detection, and low cost, the developed method can be considered as a powerful and pioneering tool for GM crops detection. Its use can also be extended to other toxin protein sensing in foods.