title: Microphase Behavior and Enhanced Wet-Cohesion of Synthetic Copolyampholytes Inspired by a Mussel Foot Protein.
abstract: Numerous attempts have been made to translate mussel adhesion to diverse synthetic platforms. However, the translation remains largely limited to the Dopa (3,4-dihydroxyphenylalanine) or catechol functionality, which continues to raise concerns about Dopa's inherent susceptibility to oxidation. Mussels have evolved adaptations to stabilize Dopa against oxidation. For example, in mussel foot protein 3 slow (mfp-3s, one of two electrophoretically distinct interfacial adhesive proteins in mussel plaques), the high proportion of hydrophobic amino acid residues in the flanking sequence around Dopa increases Dopa's oxidation potential. In this study, copolyampholytes, which combine the catechol functionality with amphiphilic and ionic features of mfp-3s, were synthesized and formulated as coacervates for adhesive deposition on surfaces. The ratio of hydrophilic/hydrophobic as well as cationic/anionic units was varied in order to enhance coacervate formation and wet adhesion properties. Aqueous solutions of two of the four mfp-3s-inspired copolymers showed coacervate-like spherical microdroplets (ϕ ≈ 1-5 μm at pH ∼4 (salt concentration ∼15 mM). The mfp-3s-mimetic copolymer was stable to oxidation, formed coacervates that spread evenly over mica, and strongly bonded to mica surfaces (pull-off strength: ∼17.0 mJ/m(2)). Increasing pH to 7 after coacervate deposition at pH 4 doubled the bonding strength to ∼32.9 mJ/m(2) without oxidative cross-linking and is about 9 times higher than native mfp-3s cohesion. This study expands the scope of translating mussel adhesion from simple Dopa-functionalization to mimicking the context of the local environment around Dopa.
authors.forename: Sungbaek
authors.initials: S
authors.lastname: Seo
authors.forename: Saurabh
authors.initials: S
authors.lastname: Das
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Zalicki
authors.forename: Razieh
authors.initials: R
authors.lastname: Mirshafian
authors.affiliation: ⊥Institute for Polymer Chemistry, University of Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Claus D
authors.initials: CD
authors.lastname: Eisenbach
authors.forename: Jacob N
authors.initials: JN
authors.lastname: Israelachvili
authors.forename: J Herbert
authors.initials: JH
authors.lastname: Waite
authors.forename: B Kollbe
authors.initials: BK
authors.lastname: Ahn
mesh_terms: D000268:Adhesiveness; D000595:Amino Acid Sequence; D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry*; D049872:Bivalvia; D004563:Electrochemistry; D008969:Molecular Sequence Data; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011506:Proteins; D019904:Polymethyl Methacrylate