(271b) Dynamic Factors Controlling Bacterial Adhesion to Polymeric and Nanopatterned Surfaces

Bacterial adhesion is generating increasing scientific interest in the context of biofilm formation and increased antibiotic resistance. While the complete elimination of biofilms poses a challenge addressed by surface chemists, the use of biofilms in remediation and other applications drives the creation of material supports on which biofilms can be controlled and maintained. To this end, we discuss here the dynamic aspects of early biofilm formation involving the capture of single cells and their interfacial response on model surfaces, specifically examining the development of electrostatic and hydrogen bonding interactions. We present here a study comparing the capture and relaxation processes of S. aureus on biocompatible PEG brushes and hydrogel coatings, polycationic antimicrobial surfaces, and nanopatterned hybrid surfaces containing PEG brush and cationic components. The work benchmarks bacterial behavior against that of silica microspheres on the same surfaces, where the negative silica charge models that on the bacteria and where silica also undergoes hydrogen bonding. Even on surfaces such as hydrogels and brushes that do not capture (arrest) bacteria, evidence for weak interactions are found. For instance in the vicinity of brushes and hydrogels, S. aureus undergo associated interfacial motions in flow such as rolling and hopping. While bare silica did not reproduce this behavior because of its greater density of binding sites, a partially PEG-modified silica was shown to behave similarly. By contrast to the motion signatures of adhesion capture on brushy surfaces, we reveal abrupt capture kinetics in flow on cationic surfaces. Beyond the dynamics of capture itself, we find, in the first 30 minutes after capture, evidence for surface-dependent interfacial relaxations that increases the tightness of bacterial adhesion, and we demonstrate how nanoscopic patterning can be adjusted to tune interfacial relaxation and antimicrobial character.