ORGANIZED SELF-ASSEMBLED LIPOYL-BETA-CYCLODEXTRIN DERIVATIVE MONOLAYER ON A GOLD ELECTRODE

An organized self-assembled monolayer of beta-cyclodextrin (beta-CD) d erivatives on a gold surface has been prepared using two lipoyl-beta-c yclodextrin derivatives with different chain lengths, which are more f lexible than heptakis (dodecyl sulfide) beta-cyclodextrin, The surface coverage of the monolayers were found to be in agreement with the sur face 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 perme ability 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 carbox ylic acid and hydroxyquinone, which can form host-guest inclusion comp lexes with beta-CD receptors. The selective transport can be controlle d by blocking the beta-CD cavities with some guest molecules such as c yclohexanol, borneol and ursodeoxycholic acid, and the controlling mod e can be expected for detection of organic compounds.