New directions and challenges in electrochemistry. Bioelectrochemistry at metal/water interfaces.

Some aspects of bioelectrochemistry at metal \ water interfaces which may provide useful information on the role played by biomolecules in biological processes are overviewed and assessed. Electrochemical reactions of water-soluble redox proteins, either immobilized on bare or functionalized electrode surfaces or free to diffuse toward the electrode, are briefly reviewed. The preparation and architecture of metal-supported biomembrane models, both noncovalently and covalently attached to the metal surface, are described. The structure of self-organized phospholipid monolayers interposed between the metal surface and the aqueous phase is examined, with particular regard to the ionizable groups and the surface dipole potential of their polar heads. Particular attention is focused on the preparation of biomembrane models capable of incorporating integral proteins in a functionally active state. The use of experimental models of biomembranes for investigating the function of integral proteins, either incorporated in biomembrane fragments or proteoliposomes adsorbed on metal-supported mixed alkanethiol \ lipid bilayers, or directly incorporated in metal-supported lipid bilayers, is described. The potential of metal-supported lipid bilayers with a hydrophilic 'spacer' interposed between the metal surface and the bilayer for fundamental studies on the function of integral proteins and for reliable and rapid drug screening is emphasized.