Electrochemical analysis of the interactions and reactivity of ferrocene-based drugs with a lipid environment: A qualitative overview

Transport, reactivity and interactions of anti-tumor ferrocene-based compounds within lipid environments have been investigated electrochemically at a glassy carbon electrode (GCE) modified with a lipid bilayer film. Cyclic voltammetry performed in the presence of an adsorbed bilipid film in a H(2)O/EtOH (8/2) mixture, clearly showed that the affinity of the starting neutral ferrocifen derivatives towards the lipidic bilayer depends on both their size and their polarity. Likewise, the electrogenerated ferrocenium derivatives were expulsed reversibly from the bilayer in agreement with their positive charge. The reactivity of ferrocifen compounds was also investigated under the same conditions and in the presence of a base in order to trigger an intramolecular ferrocene-mediated (-2e - 2H(+)) process within the lipidic film. Under these conditions, two distinct sequential electrochemical behaviors were observed depending on the base availability in the lipid layer, the magnitude of the corresponding two electrons wave being limited by the base concentration in the film. A full two-electron oxidation process, was observed as long as the amount of base present into the lipid layer was high enough to titrate the two protons released in the two-electron process. When this was sub-stoichiometric a second wave was observed at higher potential values representing the one electron oxidation of the ferrocifen excess. (C) 2011 Elsevier B.V. All rights reserved.