A robust model membrane environment has been developed to enable voltammetry experiments to be performed on low molecular weight biological molecules completely incorporated inside artificial lipid bilayer (or multilayer) membranes. The artificial supported membranes were prepared by sandwiching multilayers of lecithin between layers of Nafion that were deposited on the surface of a glassy carbon electrode. The Nafion films acted as a conduit to aid proton transfer across the lecithin solution interface, and thereby balance the charge brought about by the electrochemical reactions. Vitamin E (α-tocopherol) and vitamin K1 were separately incorporated inside the Nafion|lecithin|Nafion layers and the coated electrodes were immersed in aqueous solutions between pH 3 and 13. The membranes were conductive to ion transfer, which allowed cyclic voltammetry experiments to be performed at scan rates of at least 200 V s−1. The electrode coating procedure produced multilayer membranes with solvent-like properties enabling highly reproducible diffusion controlled voltammetric processes to be observed. Vitamin E and vitamin K1 underwent multiple electron-transfer and proton-transfer reactions inside the membranes, and in the case of vitamin E, higher scan rate voltammetric experiments allowed the detection of short-lived intermediates.

A procedure was developed for initiating electron transfer from a gold electrode to a low molecular weight electron acceptor present inside supported lipid (lecithin) bilayers, followed by further electron transfer to an electron acceptor present in an aqueous solution. The electron acceptors present in the lecithin bilayers and aqueous phase were 7,7,8,8-tetracyanoquinodimethane (TCNQ) and [Fe(III)(CN)(6)](3-), respectively. A polished planar gold disk electrode was first coated via self-assembly procedures with an alkanethiol monolayer. A phospholipid layer consisting of multiple bilayers of lecithin containing TCNQ was subsequently deposited onto the alkanethiol monolayer. The Au/alkanethiol/lecithin-TCNQ electrode was placed in an aqueous solution containing various amounts of [Fe(III)(CN)(6)](3-) and [Fe(II)(CN)(6)](4-), with 0.5 M KCl as the supporting electrolyte. In the absence of TCNQ inside the alkanethiol/lecithin layers, only a small background current was observed. When TCNQ was included in the alkanethiol/lecithin layers, the voltammetry showed features typical of a catalytic process, due to the TCNQ being reduced to TCNQ(-*) within the lecithin bilayers and then undergoing oxidation back to TCNQ via interaction with [Fe(III)(CN)(6)](3-) at the lecithin-aqueous solution interface. The procedures for preparing the alkanethiol/lecithin-TCNQ coatings were optimized in order to obtain the most reproducible voltammetric response. Experiments were also performed using tetrathiafulvalene (TTF) as an electron donor in the lipid bilayer phase.