A friend sent us a note on this this open-access paper:
Abstract: The mussel byssus has long been a source of inspiration for the adhesion community. Recently, adhesive synergy between flanking lysine (Lys, K) and 3,4-Dihydroxyphenylalanine (DOPA, Y) residues in the mussel foot proteins (Mfps) has been highlighted. However, the complex topological relationship of DOPA and Lys as well as the interfacial adhesive roles of other amino acids have been understudied. Herein, we study adhesion of Lys and DOPA-containing peptides to organic and inorganic substrates using single-molecule force spectroscopy (SMFS). We show that a modest increase in peptide length, from KY to (KY)3, increases adhesion strength to TiO2. Surprisingly, further increase in peptide length offers no additional benefit. Additionally, comparison of adhesion of dipeptides containing Lys and either DOPA (KY) or phenylalanine (KF) shows that DOPA is stronger and more versatile. We furthermore demonstrate that incorporating a nonadhesive spacer between (KY) repeats can mimic the hidden length in the Mfp and act as an effective strategy to dissipate energy.Li, Y., Cheng, J., Delparastan, P. et al. Molecular design principles of Lysine-DOPA wet adhesion. Nat Commun 11, 3895 (2020). https://doi.org/10.1038/s41467-020-17597-4
Note the Introduction:
One of the great challenges faced by man-made adhesives is binding in the presence of water, salts, and surface contaminants. Marine mussels, on the other hand, have perfected the art of adhering tenaciously to a variety of surfaces in wet conditions. The strong attachment of mussels is mediated by the byssus, a proteinaceous holdfast that is formed by secretion and solidification of specialized adhesive proteins. [. . .] Bioinspired design principles based on mimicking these interfacial proteins have been employed extensively and resulted in a variety of catechol functionalized polymers for bio-compatible adhesives, self-healing hydrogels, and surgical wound closure materials. Nevertheless, the true potential of mussel-inspiration may not be fully realized until the hidden complexities in the structure and biofabrication of these adhesive proteins is revealed. [. . .] Our results shed light on the interplay between chemical sequence and topological structure in the mussel adhesive proteins and provide a solid framework for rational design of bioinspired wet adhesives.Li, Y., Cheng, J., Delparastan, P. et al. Molecular design principles of Lysine-DOPA wet adhesion. Nat Commun 11, 3895 (2020). https://doi.org/10.1038/s41467-020-17597-4
Marine mussals have “perfected the art,” have they? If they just happen to have evolved to be so clever, why don’t they do more? It’s becoming increasingly obvious that something in nature is clever but it isn’t the mussel.