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Free keywords:
enzyme-induced polymerization,
adhesion,
mussel glue,
cohesion control,
synthetic protein mimics
Abstract:
The synthesis of artificial mussel‐glue proteins with pH triggered cohesion control mechanism is described by extending the tyrosinase activated polymerization of peptides to sequences having specific modules for cohesion control. The high propensity of those sequence sections to adapt β‐sheets is temporarily suppressed by switch defects. This allows enzymatic activation and polymerization to proceed undisturbed. The β‐sheet formation is regained after polymerization by changing pH from 5.5 to 6.8, triggering O→N acyl transfer rearrangements that activate the cohesion mechanism. The resulting artificial mussel glue proteins exhibit rapid adsorption on alumina surfaces. The coatings resist harsh hypersaline conditions, and reach remarkable adhesive energies of 2.64 mJ/m–2 on silica at pH 6.8. In in situ switch experiments, the minor pH change increases the adhesive properties of a coating by 300% and nanoindentation confirms the cohesion mechanism to improve bulk‐stiffness by ~200%.