Impedimetric Horseradish Peroxidase Sensor Based on Polyaniline-Nanofiber-Modified Microdisk Electrode Arrays

Abstract

Microdisk electrode arrays have attracted much interest because of their advantages for the development of electrochemical biosensors. However, the measured analyte current signal from these electrodes is very low and thus needs amplification. Therefore, this study demonstrates a methodology for label-free detection of horseradish peroxidase using microdisk electrode arrays with electrodeposited polyaniline. The effect of the number of disks in an electrode was examined; in addition, for signal amplification, the array was coated with polyaniline for detection of horseradish peroxidase antigen antibody interactions. Compared with bare arrays, the polyaniline-coated electrodes showed a 16-fold decrement in the measured impedance magnitude ( Z) and thus enhanced the sensitivity of electrode array. The morphology of the deposited polyaniline was characterized by scanning electron microscopy, and the structure was analyzed by X-ray diffraction measurements and UV-vis spectroscopy. The variations in the impedance magnitude (IZI) were recorded for various concentrations of horseradish peroxidase (C-HRP) in the [Fe(CN)(6)](3-/4-) redox couple. The electrode with adsorbed antibodies showed an increase in Z with increasing CHRP over a working range of 1-1000 ng/ml, and the sensors possessed a detection limit of 0.056 ng/ml.