Atrazine analysis using an impedimetric immunosensor based on mixed biotinylated self-assembled monolayer

Atrazine is one of the most commonly used pesticides in the world. Thus, it is regularly found in rain, surface, marine and ground water. For these reasons, analysis of this pollutant is of high importance for environmental protection during the forthcoming years. This work describes the development of an electrochemical immunosensor for the analysis of atrazine associated to biotinylated-Fab fragment K47 antibody. The sensors are based on mixed self-assembled monolayer consisting of 1,2 dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl) (biotinyl-PE) and 16-mercaptohexadecanoic acid (MHDA). The properties of mixed monolayer were characterized by cyclic voltammetry and impedance spectroscopy. The tethered neutravidin was used the biotin sites present in the mixed monolayer, with those associated to the biotinyl-Fab fragment K47 antibody. The electrical resistance, Rm, decreases gradually after each building step of the sensing membrane. These decreases could be attributed to rearrangements in the structure of the SAMs. The results show that immunosensor based on this method has a high sensitivity to atrazine antigen and a good linear response in the range 10–300 ng/ml with a detection limit of 20 ng/ml.