Electrostatic and steric interaction between redox polymers and some flavoenzymes in mediated bioelectrocatalysis

Abstract

H 2 O 2-generating oxidase/peroxidase (POD)-based mediated biosensors are very useful to minimize interference, but require suitable mediators which work well only for POD but not against the oxidase. Pentacyanoferrate-bound poly(1-vinylimidazole) (PVI[Fe(CN) 5 ]), PVI[Os(dcbbpy) 2 Cl] (dcbbpy = 4,4'-dicarboxy-2,2'-bipyridine) and PVI[Os(dmebpy) 2 Cl] (dmebpy = 4,4'-dimethyl-2,2'-bipyridine) have been utilized to investigate the interaction with four kinds of H 2 O 2-generating oxidases: glucose oxidase, sarcosine oxidase, choline oxidase (ChOD) and lactate oxidase. The mediated bioelectrocatalytic activities of the redox polymers for the enzymes have been determined by cyclic voltammetry in the presence of the substrates. The highly negatively charged PVI[Fe(CN) 5 ] shows practically no mediating activity against the four flavoenzymes, but strong one to POD. On the other hand, PVI[Os(dmebpy) 2 Cl] with neutral ligands shows a high activity for the oxidases except ChOD. The mediating activity of PVI[Os(dcbbpy) 2 Cl] with negatively charged ligands is much smaller than that of PVI[Os(dmebpy) 2 Cl]. These results reveal that electrostatic repulsion and steric hindrance are enhanced by using negatively charged polymers to realize minimum activity against the oxidases.

Characterization of Electron Mediator Preference of Aerococcus viridans-Derived Lactate Oxidase for Use in Disposable Enzyme Sensor Strips

“…The negatively charged ferricyanide does function as a mediator for AvLOx; however, it is not as effective as mPMS. Therefore, AvLOx can tolerate negative charges fairly well, although the negative charge of the ferricyanide seems to hinder the electron transfer slightly, which is in accordance with the results of Nieh et al (13) The positively charged hexaammineruthenium(III) is not utilized as an electron acceptor by AvLOx. This suggests that the access of the hexaammineruthenium(III) to the active center of AvLOx is blocked, despite the small size of the mediator.…”

“…(11) Finally, in 2013, Nieh et al compared metal complexes bound to polymers and concluded that the electrostatic repulsion of negative ligands and the local surface charge of the enzyme, as well as steric hindrance, lead to less efficient mediators. (13) The mediators used in this study are all small and of similar size, so steric hindrance does not explain any differences. Therefore, the most likely explanation is the electrostatic interaction of the mediators and the local surface charge of AvLOx.…”

“…(7,11,13) Some reports compared different mediators regarding their suitability for LOx-based lactate sensors. (5,6,8,11,13) However, only few papers discussed influential factors other than the local mediator concentration at the electrode/ solution interface. (5,11,13) One of the most common artificial electron mediators used in commercially available enzyme sensors is potassium ferricyanide.…”

“…(5,6,8,11,13) However, only few papers discussed influential factors other than the local mediator concentration at the electrode/ solution interface. (5,11,13) One of the most common artificial electron mediators used in commercially available enzyme sensors is potassium ferricyanide. Ferricyanide is a small, water-soluble, inorganic metal complex with reversible electron transfer kinetics.…”

Evaluation of Some Redox Mediators in the Design of Reagentless Amperometric Glucose Biosensor

“…This fact requires them to be used in solution or immobilized on the electrode surface. A variety of freediffusing and immobilized mediators, such as ferrocene (Fc) [11] and its derivatives [12], quinone compounds [13], ferricyanide [14], transition-metal complexes [15], thionine [16], tetrathiafulvalene (TTF) [9], tetracyanoquinodimethane (TCNQ) [17], tetrathiafulvalene-tetracyanoquinodimethane complex (TTF-TCNQ) [18], phenazine methosulfate (PMS) [19,20], methylene blue (MB) and methyl viologen [13] were used to improve biosensor performance.…”