A disposable voltammetric immunosensor based on magnetic beads for early diagnosis of soybean rust

Asian soybean rust is a fungal disease caused by Phakopsora pachyrhizi which is a virulent pathogen that can cause losses up to 80% in culture, reducing value and product quality. Early identification of fungus in the plant is the better way to prevent economic losses as well as spreading to neighboring farming, avoiding a rapid epidemic. In this paper, a disposable electrochemical immunosensor was developed to detect the presence of fungus mycelium, ensuring early identification of disease stages, allowing swift action to be taken. The antibody anti-mycelium of P. pachyrhizi was immobilized on magnetic microbeads, modified with a protein G, via Fc portion of antibody. The immunotest was the sandwich type, using a secondary antibody labeled with phosphatase alkaline enzyme. The optimization of experimental conditions and the analytical parameters were evaluated. The developed disposable immunosensor presented a detection limit of 90 ng mL−1. These studies provide new perspectives on using screen-printed carbon electrodes based on magnetic beads, for early diagnosis of soybean rust for analysis in field.