Electrochemical deposition of bio-inspired laccase-polydopamine films for phenolic sensors

Abstract

Hereby, a precisely controlled one-step electrode modification is presented where the enzyme laccase is immobilized during the potentiostatic deposition of a thin polydopamine film (ePDA) on carbon surfaces. The morphology, wettability, optical and electrochemical properties of the modified electrodes were accessed by atomic force microscopy, water contact angle goniometry, ellipsometry and cyclic voltammetry. The results indicate that laccase is robustly immobilized and evenly distributed in the ePDA matrix, not significantly affecting the redox behavior of the polymer. The catalytic activity of the laccase-polymer modified electrodes is confirmed by chronoamperometry for 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) detection, a well-known substrate of laccase. The proposed fast and efficient one-pot procedure is implemented on cheap disposable graphite electrodes, targeting the detection of phenolic compounds: caffeic acid, rosmarinic acid and gallic acid. The catalytic performance of the modified electrodes was evaluated in terms of reproducibility, sensitivity, limits of detection (LOD) and linear range. For gallic acid a calibration curve with a sensitivity of 19.3 mA M−1 cm−2, 1–150 μM linear range and a LOD of 0.29 μM is obtained, allowing the estimation of the low molecular weight phenols content in an extract of chestnut shell industrial waste.