The reversible binding of hydrophobically end-capped poly(ethylene glycol)s to poly-β-cyclodextrin-coated gold surfaces: a surface plasmon resonance investigation

Polymers of β-cyclodextrin (β-CD) bearing amino groups (poly-β-CD-NH2) were grafted to gold surfaces by two different procedures. Hydrophobically end-capped model-polymers were adsorbed onto resulting (poly-β-CD-NH2)-coated sensor chips by formation of inclusion complexes. Their adsorption onto the surface was followed in real time by surface plasmon resonance (SPR). Multilayered structures obtained by inclusion of adamantyl-modified poly(ethylene glycol)s (Ad-PEG) into immobilized β-cyclodextrin cavities were highly stable in aqueous media. Conditions leading to the regeneration of initial (poly-β-CD-NH2)-coated surfaces were studied by SPR. Regeneration by competitors such as polymers of β-cyclodextrin was possible. However, it was found to be a complex mechanism involving two opposite phenomena depending on the structure and composition of the (poly-β-CD-NH2) layer. Complete desorption of the bound Ad-PEG layer was also observed after exposure of the multilayered structures to organic solvents or sodium dodecylsulfate (SDS).