Nanostructured silver coatings on polyimide and their antibacterial response

• Simple approach for creation of permanent bactericidal coatings on PI foil is presented.
• Ultra-thin silver layer are transformed into island-like structure by annealing.
• Prepared structures were examined towards bacterial strains of Escherichia coli and Staphylococcus epidermidis.
• Bactericidal effect of annealed layer is significantly higher compared to as-deposited one.

We report on antibacterial activity of the silver nanostructures prepared by DC sputtering on polyimide foil (Kapton® HN). Sputtered silver nanolayers were transformed into discrete nanoislands by low-temperature post-deposition annealing. The possibility of managing nanostructure size via controlling the thickness of silver nanolayers prior to the annealing is shown. Nanostructure morphology was studied by atomic force microscopy. Atomic concentration of elements in very sample surface was determined by X-ray photoelectron spectroscopy. Integrity of silver coatings was determined by measuring its electrical sheet resistance. Antibacterial properties of the polyimide foils both pristine and silver coated before and after annealing were examined by a drip method using two bacterial strains, Escherichia coli and Staphylococcus epidermidis frequently involved in infections associated with a biofilm formation.

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