| Bacteria colonize surfaces and form complex communities termed biofilms, which pose a significant challenge in many environmental, industrial, and biomedical contexts. This thesis focused on the development of novel chemical- and materials-based approaches for the control of bacterial biofilms, with focus on those formed by Pseudomonas aeruginosa. First, we describe the discovery of a novel class of potent P. aeruginosa biofilm inhibitors and dispersers based on the 2-aminobenzimidazole (ABI) scaffold. These ABIs are among the most active P. aeruginosa anti-biofilm agents reported, and are chemically stable, non-bactericidal, and non-toxic to mammalian cells. Mechanistic studies suggested that the ABIs elicit anti-biofilm activity via a target related to the quorum sensing (QS) pathway in P. aeruginosa, but not via the LasR or RhlR receptors. Next, we describe a materials-based approach for the controlled release of ABIs using poly(lactide-co -glycolide) (PLG). PLG films containing ABI released the anti-biofilm agent for over one month in quantities that inhibited the formation of P. aeruginosa biofilms. Similar results were observed using covalent multilayers of poly(ethylene imine) (PEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA). In related studies, we report methods for the release of a non-native N-acyl-L-homoserine lactone (AHL) QS modulator from PLG films. The QS activity of the released AHL in Vibrio fischeri exceeded that when AHL was administered directly in solution suggesting that PLG protects AHLs from degradation. We also developed anti-adhesive multilayer films as an alternate anti-biofilm approach. PEI/PVDMA multilayers functionalized with hydrophobic or hydrophilic moieties supported or inhibited the growth of mammalian cells and P. aeruginosa biofilm, respectively. Lastly, we describe two chemical biological methods that can be used for the study of bacterial QS pathways. The first method was based on the small-molecule macroarray, which we applied to synthesize stilbene and triazole analogs of which several were potent agonists of the QS receptor, LuxR, in V. fischeri. The second method was based on an AHL-functionalized affinity resin, which we demonstrated could be applied to isolate LuxR-type QS receptors, such as QscR from P. aeruginosa.. |
