title: Electrocatalytic sensor devices: (I) cyclopentadienylnickel(II) thiolato Schiff base monolayer self-assembled on gold.
abstract: The fabrication of a self-assembled monolayer (SAM) of a cyclopentadienylnickel(II) thiolato Schiff base compound, [Ni(SC(6)H(4)NC(H)C(6)H(4)OCH(2)CH(2)SMe)(eta(5)-C(5)H(5))](2) on a gold electrode is described. Effective electronic communication between the Ni(II) centres and the gold surface was established by electrochemically cycling the Schiff base-doped Au electrode in 0.1M NaOH from -200mV to +600mV. The SAM-modified electrode exhibited quasi-reversible electrochemistry. The integrity of this electrocatalytic SAM, with respect to its ability to block and electro-catalyse certain Faradaic processes, was interrogated using cyclic voltammetric experiments. The formal potential, E degrees ', varied with pH to give a slope of about -30mVpH(-1). The surface concentration, G, of the nickel redox centres was found to be 1.548x10(-11)molcm(-2). By electrostatically doping the SAM using an applied potential of +700mV versus Ag/AgCl, in the presence of horseradish peroxidase (HRP), it was fine-tuned for amperometric determination of H(2)O(2). The electrocatalytic-type biosensor displayed typical Michaelis-Menten kinetics and the limit of detection was found to be 6.25mM.
authors.affiliation: Department of Chemistry, University of the Western Cape, Bellville 7535, South Africa; School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
authors.forename: Aoife
authors.initials: A
authors.lastname: Morrin
authors.forename: Richard M
authors.initials: RM
authors.lastname: Moutloali
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Killard
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Smyth
authors.forename: James
authors.initials: J
authors.lastname: Darkwa
authors.forename: Emmanuel I
authors.initials: EI
authors.lastname: Iwuoha