Mussels survive by sticking to rocks in the fierce waves or tides underwater. Materials mimicking this underwater adhesion are widely used for skin or bone adhesion, for modifying the surface of a scaffold, or even in drug or cell delivery systems. However, these materials have not entirely imitated the capabilities of mussels.
The characteristic of mussel adhesive proteins that have been mimicked so far is that they contain a large number of a unique amino acid called Dopa. Dopa is a modified amino acid with one more hydroxyl group attached to tyrosine, and research on underwater adhesion started with the fact that Dopa makes up a large component of the adhesive protein.
However, the research team questioned the fact that this excellent underwater adhesion of mussels is enabled by only one molecule and focused on observing the number and location of lysine, which is an amino acid as frequently occurring as Dopa.
As a result, the research team uncovered that Dopa and lysine are attached to each other with about half the probability. On the other hand, it was revealed that unlike what has been known so far, when Dopa and lysine are attached together, they do not always produce positive synergy. The researchers confirmed that in the case of the cation-π interaction, negative synergy is rather produced.
The findings of this study make it possible to confirm how adhesive protein of mussels was designed, and it shows promise to be applicable for research on adhesive proteins of other organisms in the future.
This research, which was recently published in Chemistry of Materials, was conducted as a part of the study titled “Understanding the underwater adhesion mechanism of adhesive organisms: controlling the balance between surface adhesion and cohesion,” which is a Mid-career Researcher Program of the Ministry of Science and ICT and the National Research Foundation of Korea.
Mincheol Shin et al, Two Faces of Amine–Catechol Pair Synergy in Underwater Cation−π Interactions, Chemistry of Materials (2021). DOI: 10.1021/acs.chemmater.1c00079