(673a) Resolving Non-Specific and Specific Adhesive Interactions of Catechols at Solid/Liquid Interfaces at the Molecular Scale

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 and binding mechanims remain unknown at the single molecular scale. Here, we use single molecule force spectroscopy [1, 2] to estimate binding energies of single catechols with a large range of opposing chemical functionalities. Our data demonstrates significant interactions of Dopa with all functionalities, yet most interactions fall within the medium-strong range of 10-20 k_BT. Only bi-dentate binding to TiO₂ surfaces exhibits a higher binding energy of 29 k_BT. Our data also demonstrates 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.

[1] S. Raman, T. Utzig, T. Baimpos, B. R. Shrestha, M. Valtiner, Nature Communications 2014, 5, 7.

[2] T. Utzig, S. Raman, M. Valtiner, Langmuir 2015, 31, 2722-2729.