(175a) Tuning Underwater Adhesion with Cation-? Interactions

Cation-Ï€ interactions govern the assembly and adhesion of many biological molecules, including the adhesion proteins of marine organisms. Increasingly, cation-Ï€ interactions are also implicated in pathological processes, like the formation of neurodegenerative protein aggregates. Thus, developing approaches for engineering cation-Ï€ interactions at the molecular level is of both fundamental and technological importance. Although cation-Ï€ bonding has been extensively studied for gas phase ion-aromatic pairs, the energetics of cation-Ï€ adhesion in biological interfaces, where many binding pairs are in close proximity, remains uncharted. In this seminar, I will discuss using molecular force spectroscopy, supplemented by solid-state NMR measurements, to show that the adhesive properties of simple aromatic and lysine-rich peptides rival those of the adhesion proteins of the marine mussel. Surprisingly, we find that peptides with the aromatic amino acid phenylalanine, a functional group that is conspicuously rare in mussel proteins, exhibit adhesion that significantly exceeds that of analogous mussel-mimetic peptides. More broadly, we demonstrate that interfacial confinement radically alters the energetics of cation-Ï€ mediated assembly, an insight that is relevant for diverse areas, ranging from combating pathological biomolecule assembly to engineering novel bio-inspired medical adhesives.