Sensitivity enhancement of a “bananatrode” biosensor for dopamine based on SECM studies inside its reaction layer

A model biosensor based on a reaction layer containing banana pulp was constructed and dopamine (DA) has been selected as analyte for the investigations. On the basis of dynamic voltammograms it was found that the optimal potential for DA detection should be −0.2 V vs. SCE, potential where the oxygen interference was avoided. Based on vertical scanning electrochemical microscopy (SECM) the optimal width of the reaction layer for the model biosensor was determined to be in between 130 and 160 μm. Optimal resting potential in periodically interrupted amperometry (PIA) detection mode was determined to be in the range from −0.02 V to −0.03 V vs. SCE. The resting time used in PIA experiments was 0.5 s. A detection limit of 2 × 10−6 M was obtained for DA by using PIA detection mode.