Polymers that respond to the presence of bacteria could be useful for detection of infection and microbial contamination. One way of providing a response is with polymers that bind to bacteria and then pass through a coil-to-globule (desolvation) transition. The coil-to-globule transition in an aqueous polymer solution occurs at a lower critical solution temperature, which is dependent on polymer structure and the aqueous environment (, ionic strength and/or pH). However, the coil to globule transition also can be induced by binding of polymer bound ligands to cell surfaces provided the ligands remain available for binding in the globule (desolvated) form. In our work we ensure this by placing the ligands at the chain ends of highly branched polymers. Here we present our recent results with this system. We compare the behavior of linear poly(N-isopropyl acrylamide) with pendant ligands to highly branched analogues. Using vancomycin as the ligand and Staphylococcus aureus as a target organism we show that linear polymers do not pass through the coil-to-globule transition on initial binding whereas branched polymers with a critical degree of branching do pass through the coil to globule transition. Nile red responds to hydrophobicity of its environment by both an increase in fluorescence intensity and a change in the wavelength of maximum absorbance. Here use these properties to provide both quantification and to probe the interaction of the polymer with the target bacteria.

Poly(N-isopropyl acrylamide) responsive to the presence of bacteria

248th National Meeting (2014)

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