An HRP based biosensor using sulphonated polyaniline
Ngamna, Orawan and Morrin, Aoife and Moulton, Simon E. and Killard, Anthony J. and Smyth, Malcolm R. and Wallace, Gordon G. (2005) An HRP based biosensor using sulphonated polyaniline. Synthetic Metals, 153 (1-3). pp. 185-188. ISSN 0379-6779
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The properties of poly (2-methoxyaniline-5-sulfonic acid) (PMAS), a water-soluble polymer, has been investigated as a potential mediator for biosensors. Addition of poly (L-Lysine) (PLL) to the PMAS renders this material water-insoluble; an important feature for aqueous based biosensors. Characterisation of various PMAS/PLL mixtures showed that a uniform and stable film could reproducibly be fabricated on ITO coated Mylar using 0.1% (w/v) PMAS and 0.05% (w/v) PLL. Immobilisation of enzyme horseradish peroxidase (HRP) onto the PMAS/PLL film was also investigated. Amperometric detection (-0.1 V vs. Ag/AgCl reference electrode) of hydrogen peroxide was investigated using the PMAS/PLL/HRP electrode as the working electrode in a three electrode cell containing phosphate buffer saline (pH 6.4) solution. Amperometric responses were observed upon the addition of hydrogen peroxide. HRP immobilised concentration was optimised to be 0.35% (w/v) at 35 μL. Loading volume was also studied and optimised to be 35 μL. The optimal condition for amperometric test was using constant applied potential at -100 mV. Detection limit of the sensor in PBS solution was 0.01 mM HO. Calibration curve in PBS pH 6.4 shows a linear response range between 0.01 and 0.1 mM HO with a sensitivity of 24.91 μA/cm mM[-1] and correlation coefficient of 0.9966.
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