Resolving Non‐Specific and Specific Adhesive Interactions of Catechols at Solid/Liquid Interfaces at the Molecular Scale

Abstract

The adhesive system of mussels evolved into a powerful and adaptive system with affinity to a wide range of surfaces. It is widely known that thereby 3,4‐dihydroxyphenylalanine (Dopa) plays a central role. However underlying binding energies remain unknown at the single molecular scale. Here, we use single‐molecule force spectroscopy to estimate binding energies of single catechols with a large range of opposing chemical functionalities. Our data demonstrate significant interactions of Dopa with all functionalities, yet most interactions fall within the medium–strong range of 10–20 k B T. Only bidentate binding to TiO2 surfaces exhibits a higher binding energy of 29 k B T. Our data also demonstrate at the single‐molecule level that oxidized Dopa and amines exhibit interaction energies in the range of covalent bonds, confirming the important role of Dopa for cross‐linking in the bulk mussel adhesive. We anticipate that our approach and data will further advance the understanding of biologic and technologic adhesives.

In situ insights into the nanoscale deposition of 5,6-dihydroxyindole-based coatings and the implications on the underwater adhesion mechanism of polydopamine coatings

“…1). Although the presence of the catechol moiety is one important contributor to the process of underwater adhesion, [37][38][39][40][41][42] some other interactions must also be responsible for this rapid deposition onto the silicon surface, e.g. electrostatic or p-p stacking.…”

The molecular mechanisms underlying mussel adhesion

“…The forces logarithmically depended on the loading rates. The experimental condition-dependent rupture forces were further exemplied by Utzig et al, 113 Kinugawa et al, 114 and Das et al 115 The effect of surface properties on DOPA adhesion Recently, using scanning tunnel microscopy (STM), Li et al found that DOPA showed different binding status and movement modes on the crystal rutile h110i surface. 116 The surface hydroxyl group greatly enhanced the diffusion ability of absorbed catechols.…”

Mussel adhesion – essential footwork

“…Quinones provide opportunities for adhesion to amine-functionalized (e.g. protein) surfaces, where the force to break (∼2 nN) is consistent with formation of a covalent interfacial quinone-amine adduct (Lee et al, 2006;Utzig et al, 2016). Such adducts, however, are unlikely to form in the highly reducing environment of the plaque interface.…”