Biofilm formation assays were based on methodology from previously published work. In brief, starting from an overnight liquid culture, a dilution containing approximately 10 8 CFU/mL was made of PAO1 strain (kind donation from Prof. Seamas Donnelly, School of Medicine, Trinity College Dublin). For each biofilm experiment, 8 wells of a round-bottomed polypropylene 96-well micro plate (Corning Costar, Sigma) were inoculated with 100 μL of this dilution, 8 wells were inoculated with the dilution and treated with the test compounds (in concentrations from 0 to 10 mM) and 8 control wells were filled with sterile medium (bacteria alone). Following 4 hours of adhesion, the supernatant, containing non-adhered cells, was removed from each well and plates rinsed using PBS solution. Following this 100 μL of fresh media was added to the control wells and fresh media with each concentration of ligand 1 or its complexes was added to the appropriate wells, the plate was then incubated for a further 24 h. After 24 h biofilm formation, the supernatants were again removed, and the wells rinsed with PBS again. Once the wells were washed, 100 μL of a 0.5% crystal violet (CV) solution was added to all wells. After 20 min, the excess CV was removed by washing the plates under running tap water. Finally, bound CV was released by adding 150 μL of 33% acetic acid (Sigma). Absorbance was measured at 590 nm.