Polymyxin peptide conjugated to the end groups of highly branched poly(N-isopropyl acrylamide) was shown to bind to a Gram negative bacterium, Pseudomonas aeruginosa. The nonbound polymer had a lower critical solution temperature (LCST) above 60 degrees C. However, binding caused aggregation, which was disrupted on cooling of the bacteria and polymer mixture. The data indicate that polymer binding of bacteria occurred by interaction of the end groups with lipopolysaccharide and that the binding decreased the LCST to below 37 degrees C. Cooling then progressed the polymer/bacteria aggregate through a bound LCST into an open polymer coil conformation that was riot adhesive to P. aeruginosa.