Examining Potential Active Tempering of Adhesive Curing by Marine Mussels

Attachment of zebra and quagga mussel adhesive plaques to diverse substrates

Like marine mussels, freshwater zebra and quagga mussels adhere via the byssus, a proteinaceous attachment apparatus. Attachment to various surfaces allows these invasive mussels to rapidly spread, however the adhesion mechanism is not fully understood. While marine mussel adhesion mechanics has been studied at the individual byssal-strand level, freshwater mussel adhesion has only been characterized through whole-mussel detachment, without direct interspecies comparisons on different substrates. Here, adhesive strength of individual quagga and zebra mussel byssal plaques were measured on smooth substrates with varying hydrophobicity-glass, PVC, and PDMS. With increased hydrophobicity of substrates, adhesive failures occurred more frequently, and mussel adhesion strength decreased. A new failure mode termed 'footprint failure' was identified, where failure appeared to be adhesive macroscopically, but a microscopic residue remained on the surface. Zebra mussels adhered stronger and more frequently on PDMS than quagga mussels. While their adhesion strengths were similar on PVC, there were differences in the failure mode and the plaque-substrate interface ultrastructure. Comparisons with previous marine mussel studies demonstrated that freshwater mussels adhere with comparable strength despite known differences in protein composition. An improved understanding of freshwater mussel adhesion mechanics may help explain spreading dynamics and will be important in developing effective antifouling surfaces.

Recent Trends in Mussel-Inspired Catechol-Containing Polymers (A Review)

Syntheses and applications of mussel-inspired polymeric materials have gained a foothold in research in recent years. Mussel-inspired chemistry coupled to Michael addition and Schiff’s base reactions was the key success for this intensive research. Unequivocally, The basic building brick of these materials is catechol-containing moiety, namely, 3,4-dihydroxyphenyl-L-alanine (L-DOPA or DOPA) and dopamine (DA). These catechol-based units within the chemical structure of the material ensure chiefly its adhesive characteristic to adherends of different natures. The newly-made catechol-bearing polymeric materials exhibit unique features, implying their importance in several uses and applications. Technology advent is being advantaged with these holdfast mussel protein-like materials. This review sheds light into the recent advances of such mussel-inspired materials for their adhesion capacity to several substrata of different natures, and for their applications mainly in antifouling coatings and nanoparticles technology.

Environmental post-processing increases the adhesion strength of mussel byssus adhesive

Marine mussels (Mytilus trossulus) attach to a wide variety of surfaces underwater using a protein adhesive that is cured by the surrounding seawater environment. In this study, the influence of environmental post-processing on adhesion strength was investigated by aging adhesive plaques in a range of seawater pH conditions. Plaques took 8-12 days to achieve full strength at pH 8, nearly doubling in adhesion strength (+94%) and increasing the work required to dislodge (+59%). Holding plaques in low pH conditions prevented strengthening, causing the material to tear more frequently under tension. The timescale of strengthening is consistent with the conversion of DOPA to DOPA-quinone, a pH dependent process that promotes cross-linking between adhesive proteins. The precise arrangement of DOPA containing proteins away from the adhesive-substratum interface emphasizes the role that structural organization can have on function, an insight that could lead to the design of better synthetic adhesives and metal-coordinating hydrogels.

Bioinspired Catechol-Based Systems: Chemistry and Applications

Catechols are widely found in nature taking part in a variety of biological functions, ranging from the aqueous adhesion of marine organisms to the storage of transition metal ions [...].