Aerosol-assisted low pressure plasma deposition of antimicrobial hybrid organic-inorganic Cu-composite thin films for food packaging applications

An innovative low pressure plasma process for deposition of copper-containing hybrid organic-inorganic thin films was developed. The discharge was fed with an aerosol of an aqueous solution of a copper complex, i.e. bis(ethylenediamine)copper(II) hydroxide and argon. Polymeric films, incorporating inorganic Cu(I) and Cu(II) compounds, were obtained. Morphological and chemical characterizations of the coatings were carried out. Antimicrobial properties were assessed on two species of Pseudomonas spp. In vitro tests were carried out by contact of the optimized films, deposited on square polycarbonate samples (~ 4 cm2), with cell suspensions of 1 × 104 CFU/mL for 18 h at 25 °C. It was demonstrated that, the hybrid organic-inorganic thin coatings have potential utilization as active packaging material, showing an antimicrobial effect of up to three orders of magnitude (final microbial concentration 105 CFU/mL), compared to control polycarbonate (final microbial concentration 108 CFU/mL). Industrial relevance An innovative low pressure plasma process for deposition of copper-based, hybrid organic-inorganic thin films was developed. The optimized thin coatings have potential industrial utilization as active packaging material, being very effective against pseudomonads. Viability of Pseudomonas was reduced by three orders of magnitude (from 108 CFU/mL to 105 CFU/mL) in the presence of developed films, thus suggesting further investigation of the technique under food packaging conditions.