Impact of Multimeric Ferrocene‐containing Cyclodecapeptide Scaffold on Host‐Guest Interactions at a β‐Cyclodextrin Covered Surface

Abstract

Among non-covalent bonds, the host-guest interaction is an attractive way to attach biomolecules to solid surfaces since the binding strength can be tuned by the nature of host and guest partners or through the valency of the interaction. For that purpose, we synthesized cyclodecapeptide scaffolds exhibiting in a spatially controlled manner two independent domains enabling the multimeric presentation of guest molecules on one face and the other face enabling the potential grafting of a biomolecule of interest. In this work, we were interested in the β-cyclodextrin/ferrocene inclusion complex formed on β-CD monolayers functionalized surfaces. By using surface sensitive techniques such as quartz crystal microbalance and surface plasmon resonance, we quantified the influence of the guest valency on the stability of the inclusion complexes. The results show a drastic enhancement of the affinity with the gradual increase of guest valency. Considering that the sequential binding events are equal and independent, we applied the multivalent model developed by the Huskens group to extract intrinsic binding constants and an effective concentration of host.

Influence of Surface Chemistry on Host/Guest Interactions: A Model Study on Redox-Sensitive β-Cyclodextrin/Ferrocene Complexes

“…Despite the wide use of host/guest interactions, our understanding of the parameters determining their efficiency at interfaces, and in particular of the role of surface chemistry, remains limited. Previous studies highlighted the importance of the parameters related to the host/guest moieties (surface density, ,– concentration in solution, , affinity, valency, ,– and lateral mobility), the surrounding liquid medium (presence of competing guests , or anions), and the underlying substrate (Au, Si, and doping level) . In particular, it has been shown that the affinity of host/guest complexes is altered at the surface compared to that in solution, with both higher and lower association constants being reported. ,,, There are studies suggesting that these effects are related to different chemical structures of guest derivatives, resulting in different combinations of binding forces during the formation of host/guest complexes (hydrophobic, electrostatic, and hydrogen bonding). , Other studies showed that electrolyte anions interact with host cavities with different affinities and, in some cases, interfere with host/guest binding. , One can expect that the parameters of the interface, including the arrangement of host/guest groups, the linkers connecting them to the surface, and the nature of diluting molecules, can also affect the efficiency of host/guest complexation and on-demand dissociation, an aspect that has not yet been studied thoroughly.…”