The mechanism of robust underwater adhesion of mussels has been the research highlight over the last two decades. Recently, it has been increasingly acknowledged that cation-π interaction plays an important role in underwater adhesion. In our previous study, we found that peptides with short sequences of phenylalanine (F) and lysine (K) amino acids capable of forming the efficient cation-π interactions when an isolated K amino acid is flanked by F amino acids. Surface force analysis and molecular dynamic simulation reveal that such sequence of amino acids minimizes repulsive hydration forces that prevent effective cation-π interactions. Recently, we furtherly study the impact of sequence on underwater adhesion of short peptides containing the motif of FKF, which is proved to be the smallest groups with underwater adhesion capacity based on our previous study. Using the surface force apparatus, we measured the adhesive force and cohesive force of peptide FKF and peptides with the sequence of XFKFX, where X can be glycine(G), serine(S) and glutamic acid(E). These peptides usually have the better capacity in cohesive mode. The most hydrophobic peptide GFKFG has the highest force in both mode which furtherly prove that removal of water molecule layer on peptides surfaces is very important for the cation-π interaction. We also found there is a relationship between the peptides film thickness and adhesive or cohesive force. Peptides can have strong interaction when there is monolayer on surfaces and when peptides self-assembly, the thickness increases, and the peptides lost most of adhesion capacity. The results provided in this study further explore the mechanism of cation-π interactions acting in underwater adhesion and provide useful insights into the design and development of high-performance underwater adhesives.

Impact of sequence on underwater adhesion of short peptides wtih cation-π synery

ACS Spring Meeting 2021

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