Electrochemical and Surface Plasmon Resonance Characterization of the Step-by-Step Self-Assembly of a Biomimetic Structure onto an Electrode Surface

Abstract

A plane gold-supported bilayer was prepared on an electrode by fusion of phospholipid (dimyristoylphosphatidylcholine (DMPC)) vesicles onto an alkanethiol (octadecylmercaptan (OM)) self-assembled monolayer (SAM). Escherichia coli pyruvate oxidase (Pox), a peripheral membrane enzyme, was incorporated into the supported bilayer. This supramolecular assembly was characterized by contact angle goniometry, electrochemical blocking studies, double-layer capacitance, and BIAlite (surface plasmon resonance) measurements. Electrochemistry of ferrocenemethanol at the gold surface was blocked by the well-ordered alkane chains of the OM monolayer. In order to prevent this blocking effect, dibenzyl disulfide (DBDS) was used to produce defect sites in the OM monolayer and to allow the reversibility of ferrocene electrochemistry. BIAlite measurements showed that fusion of DMPC on the OM + DBDS monolayer was not significantly different from the fusion of DMPC on the OM monolayer. Pox incorporation into the (OM + DBDS)/DMPC gold-supported bilayer was detected by BIAlite measurements. The activity of incorporated Pox was detected by the electrocatalytic current produced when substrate and the electron acceptor, ferricinium methanol, were present in solution.