Elastic Bounded Diffusion. Dynamics of Ferrocene-Labeled Poly(ethylene glycol) Chains Terminally Attached to the Outermost Monolayer of Successively Self-Assembled Monolayers of Immunoglobulins
journal contributionposted on 23.10.1999, 00:00 by Agnès Anne, Christophe Demaille, Jacques Moiroux
A model of elastic bounded diffusion is presented for the quantitative analysis of the dynamics of redox probes borne by the loose ends of linear and flexible polymeric chains terminally grafted to building blocks of a self-assembled construction. Experimentally, poly(ethylene glycol) chains bearing a ferrocene probe were terminally attached at the last one of a series of immunoglobulins monolayers successively self-assembled on top of a glassy carbon electrode. In cyclic voltammetry, the creation of a concentration gradient provoked a diffusion-like displacement of the ferrocene probe counterbalanced by the springlike elasticity of the terminally attached polymeric chain. The morphology and the intensity of the signal depend markedly on the distance separating the terminal attachment from the electrode surface and on the potential scan rate. The observed changes are qualitatively and quantitatively justified by the model. Both the diffusion and the elasticity can be quantitatively characterized.