A disposable immunomagnetic electrochemical sensor based on functionalised magnetic beads on gold surface for the detection of atrazine

A disposable immunomagnetic electrochemical sensor involving magnetic particles was developed and applied for the detection of atrazine. The sensor was based on a magnetic monolayer of magnetic particles coated with streptavidin, formed on a gold electrode after application of a magnetic field. The magnetic monolayer was characterized using faradaic impedance spectroscopy, cyclic voltammetry and atomic force microscopy (AFM) techniques. The magnetic monolayer formation leads to an important change in constant phase element due to a change in thickness. AFM images show that the magnetic monolayer is formed and is very dense. The atrazine interacts with biotinyl-Fab fragment K47 and the immunoreaction was characterized by impedance spectroscopy. A decrease in electron transfer resistance was observed which could be attributed to rearrangements in the magnetic monolayer. This approach leads to a sensitive detection of atrazine, acting as an antigen, with a good linear response in the range 10-600 ng/ml. (c) 2006 Elsevier Ltd. All rights reserved.