How to Increase Adhesion Strength of Catechol Polymers to Wet Inorganic Surfaces

Abstract

Mussel wet adhesion is known for its outstanding strength on a variety of surfaces. On the basis of the hypothesis that 3,4-dihydroxy­phenylalanine, a catecholic amino acid, governs mussel adhesion, chemists have put much effort into the design of adhesive synthetic polymers containing catechols. However, the exceptional properties exhibited by the native proteins were hardly captured. The attempts to make those polymers stick to wet inorganic surfaces resulted in low adhesive forces. Here we synthesized poly­(dopamine acrylamide) and measured the interaction forces with various inorganic surfaces using atomic force microscopy-based single-molecule force spectroscopy. We show that hydroxylation of the surface plays a pivotal role on the formation of strong bonds. We demonstrate that depending on the conditions, the whole range of interactions, from weak interactions to covalent bonds, can come into play.

Multivalent non-covalent interactions lead to strongest polymer adhesion

“…In force region 2 (R2, 500 to 1500 pN), previous studies showed that multiple bonds between catechol and TiO 2 are likely to be formed and show forces of above 500 pN, depending on the polymer architecture and the time in contact between the polymer and the underlying surface. 25,33,35 Therefore, catechol, quinone, amine and phenyl groups might mostly contribute to the forces in that region. In other words, several catechol groups of the PG 110 -b-P(Cat 5 -Ph 5 -A 2 ) molecular force sensor could interact simultaneously with the TiO 2 surface and the N 3 -PG 110 -b-P(Cat 5 -Ph 5 -A 2 ) layer on TiO 2 .…”

“…50 and 1000 pN. 22,[25][26][27][28][29][30][31][32][33][34][35] Additionally, SMFS on systems comprising multivalent interactions have been performed for different biological systems, obtaining detachment forces of up to 1000 pN. [36][37][38][39][40][41][42] However, the individual contributions to the overall force could not be resolved.…”

Mussel Inspired Trigger‐Detachable Adhesive Hydrogel

“…In order to improve its solubility and further improve its adhesion to other kinds of surfaces, chemical modification is necessary. One good candidate is catechol, [ 22–25 ] which has been regarded as the origin of the astonishing adhesion capacities of some marine organisms. [ 26 ] It can adhere to almost any kind of surface by covalent bond, hydrogen bonding, and π−π stacking.…”

“…One good candidate is catechol, [22][23][24][25] which has been regarded as the origin of the astonishing adhesion capacities of some marine organisms. [26] It can adhere to almost any kind of surface by covalent bond, hydrogen bonding, and π−π stacking.…”

Bioinspired Macromolecular Materials

“…Through microwave-assisted polymerization, they report on a method to make high molecular weight polymers of ∼14 kDa which form β-sheet structures characteristic of silk and self-assemble into nanoscale fibrils. Finally, Anne-Sophie Duwez next reports on the use of atomic force microscopy to characterize the adhesion of catechols to wet inorganic materials . These studies, inspired by the efficient adhesion achieved by byssus proteins of the marine mussel foot, use a polymer containing multiple catechols to reveal important surface chemistry characteristics of the adhesion interface.…”