Electrodeposited polydopamine-polyethyleneimine films as permselective coatings for oxidase-based amperometric sensors

Abstract

Polydopamine and its composites are utilized as a versatile platform for enzyme immobilization in amperometric enzyme biosensors. While numerous studies have used the strong adhesion, good biocompatibility and easy modifiability of polydopamine-based composites for the fabrication of enzyme modified electrodes, no studies have demonstrated their ability as a permselective layer to eliminate interfering currents from common electroactive interferents of ascorbic acid, uric acid and acetaminophen. In this study, we demonstrate that polydopamine- polyethyleneimine (PDA-PEI) film electrodeposited on platinum (Pt) substrate electrode suppresses electrochemical oxidation currents of ascorbic acid, uric acid and acetaminophen while retains electrocatalytic activity of Pt substrate toward electro-oxidation of H₂O₂. Based on this permselective property of the PDA-PEI film, an amperometric enzyme biosensor for selective and sensitive detection of lactate was built by using electro-oxidation current of lactate oxidase enzymatically generated H₂O₂ as sensor signal. Analyte lactate was detected with a wide linear concentration range from 0.01 to 4.5 mM and a detection limit of 3.4 μM. The developed enzyme biosensor was also capable of detecting lactate in real samples with satisfactory recovery results. This study illustrates a new property of the polydopamine-based composites for application in amperometric enzyme biosensors and could be helpful for developing selective and sensitive electrochemical biosensors to detect other analytes.