Comparison of simple aromatic amines for electrosynthesis of permselective polymers in biosensor fabrication
A range of simple aromatic amines were used to modify Pt microcylinders with insulating electrosynthesised polymers generated amperometrically in the presence or absence of a typical globular protein, bovine serum albumin (BSA), at neutral pH. Sensitivity to a typical interference species, ascorbic acid (AA), and the most common electrochemical signal molecule for oxidase enzymes, H2O2, was used to compare the suitability of the resulting polymer–protein modified electrodes for biosensor applications. Pt modified with poly(aminobenzene), PANI, gave the lowest sensitivity to AA (∼3000 times lower than bare Pt); incorporation of BSA into the polymer during synthesis had a detrimental effect on its AA-rejecting capability. The H2O2 sensitivity of the PANI-based electrodes was poor (∼7 times lower) compared to bare Pt. The behaviour of poly(1,2-diaminobenzene), PoPD, was different in many respects: its AA-blocking ability was enhanced 3-fold by the presence of BSA and its H2O2 sensitivity was similar to bare Pt. EQCM data recorded in PBS indicated that PANI films electrosynthesised at pH 7.4 were two orders of magnitude thicker than for PoPD. These differences may be due, at least in part, to the ‘ladder’ structure with phenazine rings proposed for PoPD, since they were not duplicated by other mono-substituted derivatives of aniline, such as 2-methylaniline or 1,3-diaminobenzene.