Nanostructured Coatings for Antimicrobial Applications

In this study, novel layer by layer assemblies based on Nafion, lysozyme and chitosan were developed and assessed with respect to their antimicrobial activity. A quartz crystal microbalance was used to monitor the built up of the multilayers in real time, confirming the presence of strong electrostatic interactions between the negatively charged Nafion and the positively charged particles of lysozyme and chitosan. The coatings are durable and resist detachment against flowing water, while AFM characterization reveals the presence of a complex surface topology with a high degree of roughness. The wettability of the coated surfaces reflects an interplay between the chemical nature of the deposited materials and the surface morphological characteristics. Moreover, it was observed that the antimicrobial behaviour of the coatings critically depends on the nature and the pH of the deposited layers. The ultrathin coatings comprising 6 bilayers of Nafion/lysozyme (pH=6.2) were shown to exhibit excellent antimicrobial properties, inhibiting the growth of Staphylococcus aureus and Escherichia coli by a factor of 100%. This remarkable behaviour carries great promise for the development of a new generation of highly effective antimicrobial coatings