Urease capacitive biosensors using functionalized magnetic nanoparticles for atrazinepesticide detection in environmental samples

Abstract

A new atrazine pesticide potentiometric biosensor was described using urease biomolecules immobilized onto the insulator–semiconductor electrode and different additional materials such as glutaraldehyde as a cross-linking agent, bovine serum albumin, coated nanoparticles (Fe₃O₄), cationic poly(allylamine hydrochloride) and anionic poly(sodium 4-styrenesulfonate) polyelectrolytes. The effect of atrazine molecules on the activity of free and immobilized urease was studied using the ion selective electrodes (ISEs) and capacity–potential measurements C(V). The sensitivity of the modified bioelectrode to urea addition was evaluated by the capacitance method via the relationship between the evolution of the flat band potential ΔV_FB and the urea concentration for values ranging from 23 to 0.04 mM. The detection of atrazine in solution was performed via its inhibiting action on the urease biosensor. An incubation time of 30 min was chosen to study the inhibition effect of atrazine for different concentrations on the urease biosensor. Under optimal experimental conditions, the enzymatic activity, the inhibition process and the analytical characteristics of the resulting ENFEC (Enzyme Field effect capacitive) system were investigated. As a result, the detection limit of atrazine via the inhibition of urease activity was about 0.13 μM with a dynamic concentration range from 10⁻² to 10⁻⁷ M.