Organized self-assembled lipoyl-beta-cyclodextrin derivative monolayer on a gold electrode

An organized self-assembled monolayer of beta-cyclodextrin (beta-CD) derivatives on a gold surface has been prepared using two lipoyl-beta-cyclodextrin derivatives with different chain lengths, which are more flexible than heptakis (dodecyl sulfide) beta-cyclodextrin, The surface coverage of the monolayers were found to be in agreement with the surface coverage of a highly organized monolayer of beta-CD, It has been revealed by cyclic voltammetry that the beta-CD derivative monolayers have the characteristics of: (a) selective barriers blocking the permeability for those molecules, such as ferricyanide, and p-aminophenol, which are incapable of complexing with beta-CD; and (b) have selective transport for electroactive organic species, such as ferrocene carboxylic acid and hydroxyquinone, which can form host-guest inclusion complexes with beta-CD receptors. The selective transport can be controlled by blocking the beta-CD cavities with some guest molecules such as cyclohexanol, borneol and ursodeoxycholic acid, and the controlling mode can be expected for detection of organic compounds.