Exploring the cooperative and competitive surface adhesion of polymers containing catechol and cationic residues*

Sea animals, such as mussels and sandcastle worms, have evolved a remarkable ability to adhere to wet surfaces through the utilization of a diverse array of flexible proteins. Investigating these natural adhesives holds significant promise for robust adhesion in aquatic environments such as tissue repair. Recent studies on bioadhesives have underscored the prevalence of specific residues within these proteins, notably the substantial occurrence of cationic (e.g., Lysine) and catechol (e.g., DOPA) residues. While DOPA-based polymers have demonstrated robust binding capabilities in dry conditions, their efficacy diminishes significantly when exposed to saline environments. Intriguingly, the substitution of cationic residues into the polymer has been observed to yield robust adhesion even in these challenging wet conditions. This points towards a synergistic interplay between catechol and cationic residues. In this talk, we utilize polymer density functional theory to investigate the adhesion between charged surfaces mediated by polymers with varying composition of these two critical residues. Our findings establish clear design principles crucial for optimizing and tailoring the adhesive properties of these polymers.