Electrode-Supported Biomembrane for Examining Electron-Transfer and Ion-Transfer Reactions of Encapsulated Low Molecular Weight Biological Molecules

Abstract

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.

Can gramicidin ion channel affect the dipole potential of neighboring phospholipid headgroups?

“…Cyclic voltammetry applied to Hg-supported tBLMs [11,12] is a powerful and versatile electrochemical technique, since it may also monitor the effect of a change in the rate of ion flow upon the current by varying the potential scan rate. It should be noted that applications of cyclic voltammetry to biomimetic membranes have been so far confined to the electron transfer across the lipid bilayer mediated by some redox couple [50,51], and not extended to the translocation of inorganic ions of biological interest, with only some exceptions at BLMs [46,47,52].…”

Ubiquinone-10 in gold-immobilized lipid membrane structures acts as a sensor for acetylcholine and other tetraalkylammonium cations

“…The inclusion of hydrophobic electroactive molecules in lipid bilayers also allows testing electrode reactions in a biomimetic environment [23][24][25]. The interactions of the generated redox products with the surroundings can lead to the design of sensors based on supported electroactive lipid bilayers.…”

Photocatalytic Hydrogen Generation by Vesicle‐Embedded [FeFe]Hydrogenase Mimics: A Mechanistic Study

“…In a previously reported micellar solution of 1 , the reduction process did show a pH dependence on the peak potentials and currents . This is in contrast with our finding, which indicates that the membrane environment of the vesicles under study provides a constant local effective pH to the catalyst, as observed previously in similar lipid bilayers …”

“…[38] This is in contrastw ith our finding, which indicates that the membrane environmento ft he vesicles under study provides ac onstant local effective pH to the catalyst, as observed previously in similar lipid bilayers. [39] During electrochemical measurements, vesicles appeared to be adsorbed onto the glassy carbon working electrode. This was demonstrated by removing the electrode from the solution after af ew scans, rinsing with deionized water,a nd submerging in fresh buffer solution, after which similar voltammograms were recorded.…”