An amperometric horseradish peroxidase inhibition biosensor based on a cysteamine self-assembled monolayer for the determination of sulfides

An amperometric horseradish peroxidase (HRP) inhibition biosensor based on a thiolate self-assembled monolayer (SAM) has been developed for the determination of sulfides (HS-, H2S and small amount S2-). Cysteamine SAM was applied to the gold electrode surface and HRP was then immobilized on the electrode by cross-linking with glutaraldehyde. The measurement was performed in the presence of an electron mediator hydroquinone and 0.067 M phosphate buffer of pH 6.5 at an applied potential of -150 mV versus SCE. The determination of sulfides can be achieved in the range of 0.5–12.7 μM with a detection limit of 0.3 μM. The kinetic parameters Michaelis–Menten constant (<F>Kmapp</F>) and maximum current (Imax) with and without inhibitor have also been calculated and possible mechanism has been deduced according to the variation of <F>Kmapp</F>. [Copyright &y& Elsevier]