Adsorption kinetic and properties of self-assembled monolayer based on mono(6-deoxy-6-mercapto)-beta-cyclodextrin molecules

The kinetic of the assembly and adsorption processes of mono(6-deoxy-6-mercapto)-beta-cyclodextrin (beta CDSH) on gold surfaces in situ and in real time have been investigated by surface plasmon resonance technique (SPR). The film thickness, dielectric constant and its coverage capability were determined by SPR with one-wavelength approach. To unambiguously determine the film parameters avoiding multi-layer adsorption as well as an underestimation of the binding constants of the adsorption process, the influence of the mass transport of beta CDSH was investigated and controlled. Under flow regime the SPR angle was monitored in several concentrations of thiol and the data were fitted by using a two-step adsorption model based on a fast adsorption of the thiol molecules in a first step followed by its slow rearrangement on the gold surface. Finally, the selectivity of the host-guest property of the beta CDSH monolayer was investigated using [Fe(CN)(6)](3-/4-) and ferrocenemonocarboxylic acid as redox probes. (c) 2006 Elsevier B.V. All rights reserved.6014167118119