Synthetic Polypeptide Mimics of Marine Adhesives

Abstract

Water soluble copolypeptides containing l-dihydroxyphenylalanine (DOPA) and l-lysine were prepared by ring-opening polymerization of alpha-amino acid N-carboxyanhydride (NCA) monomers. We have prepared a range of different copolymers to probe the effects of functional group composition on adhesive and cross-linking behavior. Aqueous solutions of these copolymers, when mixed with a suitable oxidizing agent (e.g., O2, mushroom tyrosinase, Fe3+, H2O2, or IO4-), formed cross-linked networks that were found to form moisture-resistant adhesive bonds to a variety of substrates (e.g., aluminum, steel, glass, and plastics). It was found that successful adhesive formation was dependent on oxidation conditions, with chemical oxidants giving the best results. Optimized systems were found to form adhesive bonds that rival in strength those formed by natural marine adhesive proteins. Our synthetic systems are readily prepared in large quantities and require no enzymes or other biological components.

Recent approaches in designing bioadhesive materials inspired by mussel adhesive protein

“…A desirable protecting group should remain stable during the synthetic chemical reaction while the deprotection technique should be chosen based on the composition of the final polymer so that its functionality is not reduced during the process. For multi‐step chemical synthesis approaches, protecting groups such as acetyl,66 acetonide,133, 134 methyl ether,135 cyclic ethyl orthoformate (Ceof),136 carboxybenzyl,137 and t ‐butyldimethylsilyl (TBDMS)138 have been utilized. Additionally, catechol forms pH responsive complex with boronic acid, which can act as a temporary protecting group in a basic aqueous solution 138, 139.…”

Mimicking biopolymers on a molecular scale: nano(bio)technology based on engineered proteins

“…However, the polylysines outperformed the synthetic polydecapeptide with the highest tensile strength on iron substrates. In other studies, artificial co-polypeptides (Yu & Deming 1998) and ter-polypeptides (Tatehata et al 2000) containing DOPA and lysine residues were synthesized and subsequently crosslinked by addition of several oxidation agents. A significant improvement in the bonding strength of these systems was not observed, since Mefp-1 was shown to form rigid coatings, but no bridging to the substrate surface, which would improve the adhesion properties (Lin et al 2007;Holten-Andersen & Waite 2008).…”

Wood production, wood technology, and biotechnological impacts

“…Amongst such secondary surface reactions could be the gluing together of two surfaces. Furthermore, synthetic polypeptides containing DOPA can be produced showing adhesive properties (Yu & Deming 1998). For optimising protein-based wood adhesives, mussel proteins served as a model to design DOPA-grafted soybean proteins.…”