Hydration and Dynamics of Ligands Determine the Antifouling Capacity of Functionalized Surfaces

Biofouling is a multibillion dollar problem in the modern world, stimulating a large research effort in developing antifouling surface coatings. Existing theories that attempt to explain underlying molecular mechanisms of biofilm formation and its attenuation are not consistent with experiments and focus on different aspects of the interactions. To address this knowledge gap, we report a computational molecular dynamics study in which we assess how chemistry and surface density of commonly used antifouling surface ligands affect the interfacial properties relevant to biofouling. We compare the hydration behavior and chain dynamics of poly(ethylene glycol) (PEG) and poly(2-oxazoline) (POX) modified silica surfaces as a function of chemical composition and grafting density. We show that PEG systems exhibit greater chain dynamics, while POX systems show superior hydropathicity and hydration behavior. The observed structure-property relations for the PEG-and POX-modified surfaces provide an improved understanding of the effects of molecular features on antifouling properties and highlight the importance of ligand mobility and interfacial water structure and dynamics for antifouling efficacy. The findings can be exploited in the rational design of biofouling-resistant surfaces for industrial and biomedical applications.