title: ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation ofStaphylococcus epidermidisbiofilms.
abstract: We found that a ZnO film of 2 μm thickness which was laser-deposited at room temperature onto a plain soda lime glass substrate, exhibits notable antibacterial activity against a biofilm ofStaphylococcus epidermidiswhen back-illuminated by a UVA light source with a peak emission wavelength of about 365 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-visible absorption spectroscopy, Raman spectroscopy and x-ray photoemission spectroscopy (XPS) were used to characterize the ZnO films before and after the interactions with the biofilm and the ultraviolet light, respectively. The as-deposited film was highly textured with the wurtzite (0002) in-plane orientation (c-axis perpendicular to ZnO surface) and had a surface rms roughness of 49.7 nm. In the as-deposited film, the Zn to O ratio was 1 to 0.95. After the UV and biofilm treatments, the ZnO film surface had become rougher (rms roughness 68.1 nm) and presented uniform micron-sized pitting randomly distributed, while the zinc to oxygen ratio had become 1 to 2.2. In this case, both the UV-visible and Raman spectra pointed to degradation of the structural quality of the material. On the strength of these data, we propose a model for the mediation of the bactericidal activity in which the photogeneration of highly oxidizing species and the presence of active surface defect sites both play an important role. This study is of particular interest for the acute problem of disinfection of pathogenic biofilms which form on medical device/implant surfaces.
authors.affiliation: National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Mosnier
authors.affiliation: National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: O'Haire
authors.affiliation: National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Enda
authors.initials: E
authors.lastname: McGlynn
authors.affiliation: National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Henry
authors.affiliation: Surface and Interface Research Laboratory, School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: McDonnell
authors.affiliation: Department of Physiology and Medical Physics, The Royal College of Surgeons in Ireland, St Stephen's Green, Dublin 2, Ireland.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Boyle
authors.affiliation: Department of Physiology and Medical Physics, The Royal College of Surgeons in Ireland, St Stephen's Green, Dublin 2, Ireland.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: McGuigan
keywords: ZnO; antibacterial coatings; biofilms; photocatalytic activity; pulsed laser deposition; zinc oxide