(323d) Conjugation of DOPA and Amyloid Structures for Molecular Design of Underwater Adhesives

Adhesives capable of sticking to various types of surfaces in underwater and high moisture conditions are required for a large array of applications such as marine coatings, sealants, medical devices, and wet living tissue repair. However, typical industrial adhesives are primarily developed for dry applications and perform poorly in wet environments or are highly specific to particular surfaces and not suitable for broad use. A viable and cost-effective strategy to address this issue is to develop generic adhesives that can be used for multiple types of surfaces in water or high moisture conditions.

One approach researchers have taken to develop new adhesives is to draw inspiration from the natural glues produced by aquatic organisms capable of strong, moisture-resistant adhesion to various surfaces. Analysis of these glues has shown that these organisms’ abilities to adhere to a multitude of surfaces involve L-3,4-dihydroxyphenylalanine (DOPA) and functional amyloid nanostructures.

The objective of this project is to computationally design bio-inspired underwater adhesives that are stronger than those currently reported in the literature by analyzing and combining the adhesive capabilities of DOPA and amyloid-forming peptides in wet conditions. Explicit solvent atomistic simulations can give insight into the interactions underlying surface adhesion in the presence of water, which can then be used to guide the design of DOPA-amyloid conjugates for underwater adhesion.

Motivated by the concern that DOPA groups might cluster in a way that interferes with their ability to adsorb to surfaces, we investigated the behavior of DOPA monomers in water. In this study, it was found that DOPA was unlikely to cluster significantly at concentrations lower than 1.0 M. DOPA-containing chains (alternating DOPA and glycine groups) were then simulated in water to examine the intra-molecular interactions of the chain, wherein we found that there were unlikely to be interactions detrimental to the adhesion process. We also simulated DOPA molecules on a silica surface and found that they readily adsorb onto silica.

With this understanding of DOPA’s behavior under water and at silica surfaces, we began designing a DOPA-amyloid conjugate capable of generic underwater adsorption to varied surfaces. The amyloid-forming peptide KLVFFAE was chosen for the initial design as it is known to self-assemble into functional amyloid nanostructures. Simulations of the conjugated DOPA-amyloid chains showed that the hydroxylated phenyl rings on the DOPA motifs did not interact with the rest of the chain, which leaves them free to bind to the surface. Future work will focus on furthering understanding of the behavior of DOPA-amyloid chains at model surfaces and how changes in the backbone of the DOPA-containing chain and in the sequence of the amyloid-forming peptide affect adhesion on the model surfaces.