Microelectrode arrays for horseradish peroxidase based biosensor

Abstract

The overall aims of this research were to fabricate the poly(o-phenylinediamine dihydrochoride/ horseradish peroxidase/polyaniline and poly(o-phenylinediamine dihydrochoride/ horseradish peroxidase/ gold particles/ polyaniline microelectrode arrays. The thesis, therefore, was divided into three different sections namely; microelectrode arrays fabrication, horseradish peroxidase/poly aniline microelectrode arrays, and horseradish peroxidase/gold particles/polyaniline microelectrode arrays. In first part, an insulating film poly(o-phenylinediamine dihydrochoride was firstly electrodeposited on glassy carbon electrode for 50 cycles. An insulating film was achieved and was then sonicated for 17.30 min for microelectrode formation with 3.15% RSD reproducibility. The two cavity sizes were found, microns and submicrons of microelectrode cavity population were approximately at 7 x 10⁴ and 17 x 10⁴ pores cm⁻², respectively. In the second part, the enzyme and aniline were electrodeposited on microelectrode cavities for 20 cycles to form the horseradish peroxidase/polyaniline protrusions. The 1 x 10⁻¹⁵ to 1x10⁻⁶ M range of phenol detection was achieved. In the final part, gold particles were electrodeposited on the microelectrode cavities by applying a fixed potential of -200 mV for 30 sec. The spherical gold particles were formed in microelectrode cavities and the resulting CV of sigmoidal shape was obtained indicating microelectrode characteristics. The reproducibility of these gold incorporated microelectrodes was determined at 8.17 % RSD. An enzyme and aniline were then electrodeposited, the enzyme/polyaniline thin film was found to cover the gold particle surfaces. The phenol detection range was determined from 1x10⁻¹⁵ - 1 x 10⁻³ M. The incorporation of gold particles resulted in current enhancement of 74.30 % compared with those of without. Moreover, the current responses after ten repeated uses were approximately 43.92% and 58.94% for with and without gold particles microelectrode arrays of the initial responses.