(569c) Dynamic Adhesion of Staphylococcus Aureus to Poly(ethylene glycol) Surfaces

Reversible adhesion of bacteria occurs on the time scale of seconds through physicochemical interactions of the bacteria with the surface. In flow, the translational velocity of biocolloids slows until either sufficient binding energy is achieved and the attachment occurs, or the biocolloid returns to bulk flow. This process of dynamic adhesion or â??rollingâ? has been reported to enhance and spread bacterial colonization on antifouling surfaces. In this work, we investigated the dynamic adhesion of clinically relevant methicillin-resistance Staphylococcus aureus to five poly(ethylene glycol) (PEG) materials. We synthesized three PEG hydrogels with distinct mechanical properties and mesh sizes: stiff (6500 kPa, 10 Ã?), soft (310 kPa, 27 Ã?), and decoupled soft (220 kPa, 41 Ã?), as well as two planar brushes, 2k and 5k. In general, the subpopulation of dynamically adherent S. aureus sustained rolling for ~12 µm intervals on the brushes and hydrogels. We found that when S. aureus dynamically adhered to a surface, it was highly likely to experience subsequent adhesion events. This was especially true for S. aureus on stiff hydrogels and 5k brushes where >85% of the cells adhered at least twice. As the length of interaction remained constant over each encounter, the residence time of each S. aureus on the surface provided a universal metric to compare surfaces. For example, on average S. aureus interacted 5 s longer on the stiff than on the soft hydrogels (41 Å or 27 Å). This implies that stiff hydrogel surfaces are less effective at resisting bacterial attachment because there is an increased likelihood that S. aureus will permanently attach downstream. This fundamental study investigates how S. aureus interact and adhere with PEG materials holds potential to facilitate the design of next generation of antifouling surfaces.