One-pot preparation of SBP-PANI-PAA-ethylene glycol diglycidyl ether sensor for electrochemical detection of H 2 O 2

Abstract

Soybean seed coat peroxidase (SBP) was used in combination with aniline (ANI), acrylic acid (AA), ethylene glycol diglycidyl ether (EGDE) and H2O2, to prepare a biosensor in one-pot synthesis strategy. SBP catalyzed the chemical polymerization of ANI initiated by H2O2, to give the conductive polymer (PANI) in acidic medium where acrylate acted as dopant. Further reactions between free radicals, AA and the diepoxy EGDE determined the entrapment of the SBP together with PANI in a hydrogel on the electrode surface, becoming wired for the amperometric detection of H2O2 at neutral pH and −100 mV vs Ag/AgCl. On the other hand, the absence of AA and EGDE in the reaction mixture led to an unstable sensor modifier and an erratic response to H2O2. The apparent Km for immobilized SBP in the flow system was 0.0763 mM, lower than the parameter for the free enzyme at pH 7.0. Quantitative analysis of H2O2 was carried out in a flow injection system (FIA); the calibration plot was linear in the range of 5.0–50 μM, with a limit of detection of 2.2 μM. A dental bleaching sample was successfully analyzed and the catalase test results demonstrated the specificity of the response.