Mixed hybrid bilayer lipid membrane incorporating valinomycin: improvements in preparation and functioning

We report the prepn. and characterization of a microcryst. Au electrode chem. modified with a self-assembled monolayer (SAM) of a beta-cyclodextrin (beta-CD) deriv. having attached suitably spaced ferrocene (FC) redox centers. The per-6-thio-beta-CD (S-beta-CD), SAM was investigated by cyclic voltammetry (CV) by using ferrocyanide and ferrocene carboxylic acid (FCA) as electrochem. probes. The mediator-tethered electrode was obtained by attaching a previously prepd. (by a SN2 reaction) FC deriv. to secondary OH groups of beta-CD, self-assembled on the Au surface. The obtained mediator-tethered electrode was characterized by CV, by using the above-mentioned electrochem. probes and (even if on a little extent) by microscopic ones. CV expts. in Fe(CN)6-4 solns. provide evidence for the electron transfer (eT) mediating role played by FC centers tethered to beta-CD SAM, of importance in the perspective of realizing oxygen-independent biosensors based on oxidase enzymes.