Mechanical Properties and Concentrations of Poly(ethylene glycol) in Hydrogels and Brushes Direct the Surface Transport of Staphylococcus aureus

Surface-associated transport of flowing bacteria, including cell rolling, is a mechanism for otherwise immobile bacteria to migrate on surfaces and could be associated with biofilm formation or the spread of infection. This work demonstrates how the moduli and/or local polymer concentration play critical roles in sustaining contact, dynamic adhesion, and transport of bacterial cells along a hydrogel or hydrated brush surface. In particular, stiffer more concentrated hydrogels and brushes maintained the greatest dynamic contact, still allowing cells to travel along the surface in flow. This study addressed how the mechanical properties, molecular architectures, and thicknesses of minimally adhesive poly(ethylene glycol) (PEG)-based coatings influence the flow-driven surface motion of Staphylococcus aureus MS2 cells. Three protein-repellant PEG-dimethylacrylate hydrogel films (∼100 μm thick) and two protein-repellant PEG brushes (8–16 nm thick) were sufficiently fouling-resistant to prevent the accumulation...