Electropolymerization of pyrrole-tailed imidazolium ionic liquid for the elaboration of antibacterial surfaces
Résumé
A strategy was developed to prepare antibacterial surfaces by electropolymerization of a pyrrole-functionalized imidazolium ionic liquid bearing an halometallate anion. The objective was to combine the antibacterial efficiency of polypyrrole with those of the ionic liquid components (cation and anion). For this, the pyrrole-functionalized imidazolium monomer [PyC8MIm]Br was synthesized and coordinated to ZnCl2. The antibacterial properties of the pyrrole-functionalized imidazolium monomers with bromide and the halometallate anion were evaluated against E. coli and S. aureus by measurement of their minimum inhibitory concentration (MIC) values. Surprisingly, different trends were observed. Against E. coli a decrease in MIC values was observed upon the incorporation of ZnCl2 while an increase in MIC values was obtained against S. aureus. Mixtures of pyrrole and the pyrrole-functionalized ionic liquid were then used for the electrodeposition of polypyrrole films on Fluoride doped Tin Oxide (FTO) substrates. The films were carefully characterized by X-ray Photoelectron Spectroscopy (XPS), water contact angle measurements, profilometry, and Scanning Electron Microscopy (SEM). The antibacterial activity of the polypyrrole-films was determined both by disk diffusion method and by the colony forming units (CFU) counting method over time. Films obtained by incorporation of the pyrrole-functionalized imidazolium monomer with halometallate anion showed excellent antibacterial properties, much higher than those of polypyrrole alone which validate our strategy. Furthermore, the antibacterial properties were much higher against Gram-positive than against Gram-negative bacteria. Finally, the antibacterial
performances over time were tuned by the concentration of the pyrrole- functionalized ionic liquid monomer used.
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