Marine mussels are unbeatable when it comes to underwater adhesive strategies. They can attach to virtually all inorganic and organic surfaces, tenaciously sustaining their bonds even in saltwater under turbulent wave-swept conditions.
It’s the foot of the mussel that enables such strong attachment by producing a biological glue for adhering to rocks and other objects. Key to its adhesiveness is a family of unique proteins called mussel adhesive proteins which contain a high concentration of the catecholic amino acid DOPA (dihydroxyphenylalanine).
Creating synthetic adhesives that mimic the adhesive chemistry practiced by marine mussels has been an area of great interest. Various synthetic polymers have been functionalized with catechols to provide diverse adhesive, sealant, coating, and anchoring properties, particularly for critical biomedical applications. The catechol-based chemistry has inspired a variety of applications ranging from hard and soft tissue repair to drug delivery to magnetic imaging agents. Another area of interest is related to industrial use including under water paints and coatings to prevent biofouling on surfaces like ships’ hulls or piping.
Controlling adhesion under wet conditions
An article titled “A direct biocombinatorial strategy towards next generation mussel-glue inspired saltwater adhesives.” was published in the Journal of the American Chemical Society. This study stressed that adhesion under sea-water conditions represents one of the major challenges for both underwater glues and bioinspired coatings. Controlling wet adhesion of synthetic macromolecules by analogue processes promises to strongly impact materials sciences by offering advanced coatings, adhesives and glues.
The research group, Hans G Börner from Max Planck Institute along with collegues from University of Bayreuth and Humboldt-Universität, has integrated enzymatic processing steps into phage display biopanning to develop an advanced biocombinatoric screening strategy that enables the selection of enzyme triggered adhesive peptides for construction aluminum. Methods used were peptide/conjugate activation, UV/vis spectroscopy, single molecule AFM measurements and Quartz Crystal Microbalance. The study demonstrated the identification of activable adhesion domains and provides further insights into the conserted process of complex bioadhesion. The extended phage display procedure provides a generic way to non-natural peptide adhesion domains, which not only mimic nature but improve biological sequence sections extractable from mussel-glue proteins.
A deeper understanding of mussel adhesive chemistry and its regulation is likely to inspire improvements in adhesive technology especially in wet applications.