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Zinc release from atomic layer deposited zinc oxide thin films and its antibacterial effect on Escherichia coli

•ZnO films were highly antibacterial even in dark conditions.•The zinc ions rather are responsible for the antibacterial effect.•ALD grown Al2O3 layer on ZnO films showed good blocking for the zinc dissolution.•The antibacterial effect may be controlled by the thickness of Al2O3/ZnO film. Zinc oxide...

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Bibliographic Details
Published in:Applied surface science 2013-12, Vol.287, p.375-380
Main Authors: Kääriäinen, M.-L., Weiss, C.K., Ritz, S., Pütz, S., Cameron, D.C., Mailänder, V., Landfester, K.
Format: Article
Language:English
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Summary:•ZnO films were highly antibacterial even in dark conditions.•The zinc ions rather are responsible for the antibacterial effect.•ALD grown Al2O3 layer on ZnO films showed good blocking for the zinc dissolution.•The antibacterial effect may be controlled by the thickness of Al2O3/ZnO film. Zinc oxide films have been grown by atomic layer deposition (ALD) at different reaction temperatures and in various thicknesses. Zinc-ion release has been examined from the ZnO films in water and in phosphate buffered saline solution (PBS). Additionally, the antibacterial effect has been studied on Escherichia coli. The thickness of the ZnO film or its crystal orientation did not affect the rate of dissolution. ALD grown aluminum oxide films were deposited on top of the ZnO films and they acted as an effective barrier against zinc dissolution. The bacteriostatic effect was not dependent on the film thickness but both 45nm and 280nm thick ZnO films significantly reduced bacterial attachment and growth in dark conditions by 99.7% and 99.5%, respectively. The results indicated that photoirradiation is not required for to enhance antibacterial properties of inorganic films and that the elution of zinc ions is probably responsible for the antibacterial properties of the ZnO films. The duration of the antibacterial effect of ZnO can be controlled by accurate control of the film thickness, which is a feature of ALD, and the onset of the antibacterial effect can be delayed by a time which can be adjusted by controlling the thickness of the Al2O3 blocking layer. This gives the possibility of obtaining dual antibacterial release profiles through a nanolaminate structure of these two materials.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2013.09.162