title: Nanostructured Ag(4)O(4) films with enhanced antibacterial activity.
abstract: Ag(4)O(4) (i.e. silver(I)-silver(III) oxide) thin films with tailored structure and morphology at the nanoscale have been grown by reactive pulsed laser deposition (PLD) in an oxygen-containing atmosphere and they are shown to exhibit a very strong antibacterial activity towards Gram-negative bacteria (E. coli) and to completely inhibit the growth of Gram-positive bacteria (S. aureus). The formation of this particular high-valence silver oxide is explained in terms of the reactions occurring during the expansion of the ablated species in the reactive atmosphere, leading to the formation of low-stability Ag-O dimers and atomic oxygen, providing reactive species at the substrate where the film grows. PLD is shown to allow control of the structure (i.e. crystallinity and grain size) and of the morphology of the films, from compact and columnar to foam-like, thus allowing the deposition of nanocrystalline films with increased porosity and surface area. The antibacterial action towards E. coli is demonstrated and is shown to be superior to that of nanostructured Ag-based medical products. This can be related to the release of Ag ions with high oxidation number, which are known to be very reactive towards bacteria, and to the peculiar morphology at the nanoscale resulting in a large effective surface area.
authors.affiliation: Politecnico di Milano, Dipartimento di Chimica, Materiali e Ingegneria Chimica 'G. Natta', Piazza Leonardo da Vinci 32, 20133 Milano, Italy. NEMAS-Center for NanoEngineered Materials and Surfaces and IIT-Italian Institute of Technology, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Dellasega
authors.forename: A
authors.initials: A
authors.lastname: Facibeni
authors.forename: F
authors.initials: F
authors.lastname: Di Fonzo
authors.forename: M
authors.initials: M
authors.lastname: Bogana
authors.forename: A
authors.initials: A
authors.lastname: Polissi
authors.forename: C
authors.initials: C
authors.lastname: Conti
authors.forename: C
authors.initials: C
authors.lastname: Ducati
authors.forename: C S
authors.initials: CS
authors.lastname: Casari
authors.forename: A
authors.initials: A
authors.lastname: Li Bassi
authors.forename: C E
authors.initials: CE
authors.lastname: Bottani