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In biology, processes such as cell-cell recognition and the initiation of signal transduction depend on the formation of multiple noncovalent complexes between substrates or ligands and membrane-bound receptors. Multiple, instead of isolated, host-guest interactions enhance binding affinity as well as selectivity.[1] Here we have investigated the role of multiple noncovalent interactions in molecular recognition at a membrane surface by using a model system consisting of bilayer vesicles of hydrophobically modified cyclodextrins [2] (CDs; the membrane receptors) in combination with monomer and polymer guest molecules [3] (the substrates). Molecular recognition and multiple host-guest interactions have been described for CD dimers [4] (including CD dimers in the presence of liposomes [5] ) and polymers [3, 6] as well as CD micelles [7] and self-assembled CD monolayers.[8] The anchoring of hydrophobically modified polymers into liposomes has also been studied.[9] We demonstrate that poly(isobutene-altmaleic acid) substituted with hydrophobic p-tert-butylphenyl groups binds very strongly and selectively to the surface of CD bilayer vesicles, without affecting the integrity of the vesicles. No interaction is observed when the membrane does not contain host molecules or when the polymer does not contain hydrophobic guest substituents.The CD vesicles used in this study were composed of 1, which is b-CD substituted with S-dodecyl groups on the primary side and oligo(ethylene glycol) groups on the

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