Molecular Mechanics of Mussel InspirCopyed Polymers and Coatings

A number of marine organisms rely on adhesive secretions for attachment to substrates in wet, turbulent environments. In the case of mussels, adhesion is mediated by the byssus- a remarkably strong and tough tissue comprised of collagenous protein threads terminally anchored by an adhesive pad. Byssal proteins have very specialized amino acid compositions, likely related to the specific challenges of achieving adhesion in the wet marine environment. Several byssal proteins contain high levels of 3,4-dihydroxy-L-alanine (DOPA), and there is a growing interest in developing mussel-inspired materials that contain catechols and other functional groups such as primary amine. Mussel inspired coatings derived from the spontaneous polymerization of dopamine, so-called ‘polydopamine’ coatings, have been widely reported in the literature for their ability to be deposited on a variety of substrates. However, the composition of polydopamine remains unknown. In this talk, we will describe our recent results on the molecular mechanics of polydopamine and related coatings using single molecule force spectroscopy. The results favor a ‘polymer’ model of polydopamine structure, casting doubt on models suggesting polydopamine is a supramolecular aggregate of small molecules and oligomers.