Laccase Based Synergistic Electrocatalytical System

Abstract

Bioelectrodes employing the conversion of N-substituted phenothiazine/hexacyanoferrate(II) and N-substituted phenoxazine/hexacyanoferrate(II) that act as synergistic substrates were built using graphite electrode and recombinant laccase. The response of the bioelectrodes to low reactive substrate (hexacyanoferrate(II)) increases 2.9 -97 times in presence of high reactive phenothiazine or phenoxazine mediator. The sensitivity of the bioelectrodes reaches 0.5 -14.3 A/M · cm 2 . To background a scheme of bioelectrodes action the kinetics of laccase-catalyzed synergistic substrates oxidation was investigated in homogenous solution. A satisfactory agreement of experimentally determined rate constants and calculated using parameters of bioelectrocatalytical system confirms the scheme of bioelectrodes action.

Computational Modeling of Mediator Oxidation by Oxygen in an Amperometric Glucose Biosensor

“…Let us introduce B O 2 , which shows the biosensor response sensitivity to oxygen, $B_{{\text{O}}_2}=\frac{i_{st}(o_0=0)-i_{st}(o_0=c_{{\text{O}}_2})}{i_{st}(o_0=0)}$where i st ( o 0 = 0) is the biosensor response in anaerobic conditions, i st ( o 0 = c O 2 ) is the biosensor response in aerobic conditions and c O 2 = 2.53 × 10 −7 mol/m 3 is the oxygen concentration in water [40]. …”

Modelling of Amperometric Biosensor Used for Synergistic Substrates Determination

“…The understanding the nature of the synergistic effect is of crucial importance for preparation of highly sensitive biosensors [13,15,26]. For a kinetic analysis of the biosensor operation, let us introduce ῡ 1 , ῡ 2 , ῡ 3 , ῡ 4 as the average rates of the reactions (1a), (1b), (1c), (1d) taking place in the enzyme layer, ${\overline{\upsilon }}_1=k_1{\overline{e}}_{ox}\overline{r}$ ${\overline{\upsilon }}_2=k_2{\overline{e}}_{\mathit{\text{red}}}{\overline{s}}_1$ ${\overline{\upsilon }}_3=k_3{\overline{e}}_{\mathit{\text{red}}}{\overline{s}}_2$ ${\overline{\upsilon }}_4=k_4{\overline{s}}_1{\overline{p}}_2$where r̄, s̄ 1 , s ¯ 2 , p̄ 1 , p̄ 2 , ē ox and ē red stand for the average concentrations of R, S 1 , S 2 , P 1 , P 2 , E ox and E red in the enzyme layer.…”

“…This phenomenon is employed in biosensors for a high sensitivity determination of synergistic substrates [13–15]. …”

Modelling glucose dehydrogenase-based amperometric biosensor utilizing synergistic substrates conversion

“…The synergistic schemes of the substrates conversion are of particular interest due to applying them to producing highly sensitive bioelectrodes and powerful biofuel cells [14]. The synergistic substrates conversion has been demonstrated using glucose oxidase, carbohydrate oxidase and laccase [15][16][17][18].…”