Screen-printed carbon electrodes modified with cellobiose dehydrogenase: Amplification factor for catechol vs. reversibility of ferricyanide

A number of screen-printed carbon electrodes (SPCEs) have been electrochemically studied revealing strong correlation between the reversibility of the Fe(CN)/Fe(CN) couple and the sensitivity for catechol at the same electrodes modified with cellobiose dehydrogenase (CDH). Pretreatment of the electrode surfaces increased both the heterogeneous ferricyanide reaction rate and the catechol sensitivity. From cyclic voltammetric and chronoamperometric measurements of Fe(CN) it was concluded that the tested SPCEs behave as microelectrode arrays. Using the pinhole model the fraction of electroactive area was determined to directly correlate to a faster heterogeneous electron transfer for ferricyanide and a higher CDH-modified biosensor sensitivity for catechol. An electroactive area of 50% and higher is sufficient to create a sufficiently good biosensor for catechol.