Inactivation of bacteria under visible light and in the dark by Cu films. Advantages of Cu-HIPIMS-sputtered films

• Published in: Environmental science and pollution research international 2012-11, Vol.19 (9), p.3791-3797
• Main Authors: Ehiasarian, A., Pulgarin, Cesar, Kiwi, John
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - toxicity; Antimicrobial agents; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bacteria; Biodegradation; Bordeaux; Coatings; Copper; Copper - chemistry; Copper - toxicity; Cotton; E coli; Earth and Environmental Science; Ecotoxicology; Electron microscopy; Electrons; Environment; Environmental Chemistry; Environmental Health; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - growth & development; Fabrics; Inactivation; Intermediates; Kinetics; Light; Mass spectrometry; Microbial Viability; Nanoparticles; Oxidation; Photocatalysis: fundamentals and applications in JEP 2011; Photoelectron spectroscopy; Plasma; Polyesters; Scientific imaging; Spectroscopy; Studies; Textiles; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-011-0734-7

Introduction The Cu polyester thin-sputtered layers on textile fabrics show an acceptable bacterial inactivation kinetics using sputtering methods. Materials and methods Direct current magnetron sputtering (DCMS) for 40 s of Cu on cotton inactivated Escherichia coli within 30 min under visible light and within 120 min in the dark. For a longer DCMS time of 180 s, the Cu content was 0.294% w / w , but the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40-s sputtered sample. Results and discussion This observation suggests that Cu ionic species play a key role in the E. coli inactivation and these species were further identified by X-ray photoelectron spectroscopy (XPS). The 40-s sputtered samples present the highest amount of Cu sites held in exposed positions interacting on the cotton with E. coli . Cu DC magnetron sputtering leads to thin metallic semi-transparent gray–brown Cu coating composed by Cu nanoparticulate in the nanometer range as found by electron microscopy (EM). Cu cotton fabrics were also functionalized by bipolar asymmetric DCMSP. Conclusion Sputtering by DCMS and DCMSP for longer times lead to darker and more compact Cu films as detected by diffuse reflectance spectroscopy and EM. Cu is deposited on the polyester in the form of Cu 2 O and CuO as quantified by XPS. The redox interfacial reactions during bacterial inactivation involve changes in the Cu oxidation states and in the oxidation intermediates and were followed by XPS. High-power impulse magnetron sputtering (HIPIMS)-sputtered films show a low rugosity indicating that the texture of the Cu nanoparticulate films were smooth. The values of R q and R a were similar before and after the E. coli inactivation providing evidence for the stability of the HIPIMS-deposited Cu films. The Cu loading percentage required in the Cu films sputtered by HIPIMS to inactivate E. coli was about three times lower compared to DCMS films. This indicates a substantial Cu metal savings within the preparation of antibacterial films.