title: Reactive combinatorial synthesis and characterization of a gradient Ag-Ti oxide thin film with antibacterial properties.
abstract: The growing demand for orthopedic and dental implants has spurred researchers to develop multifunctional coatings, combining tissue integration with antibacterial features. A possible strategy to endow titanium (Ti) with antibacterial properties is by incorporating silver (Ag), but designing a structure with adequate Ag(+) release while maintaining biocompatibility has been shown difficult. To further explore the composition-structure-property relationships between Ag and Ti, and its effects against bacteria, this study utilized a combinatorial approach to manufacture and test a single sample containing a binary Ag-Ti oxide gradient. The sample, sputter-deposited in a reactive (O2) environment using a custom-built combinatorial physical vapor deposition system, was shown to be effective against Staphylococcus aureus with viability reductions ranging from 17 to above 99%, depending on the amount of Ag(+) released from its different parts. The Ag content along the gradient ranged from 35 to 62 wt.%, but it was found that structural properties such as varied porosity and degree of crystallinity, rather than the amount of incorporated Ag, governed the Ag(+) release and resulting antibacterial activity. The coating also demonstrated in vitro apatite-forming abilities, where structural variety along the sample was shown to alter the hydrophilic behavior, with the degree of hydroxyapatite deposition varying accordingly. By means of combinatorial synthesis, a single gradient sample was able to display intricate compositional and structural features affecting its biological response, which would otherwise require a series of coatings. The current findings suggest that future implant coatings incorporating Ag as an antibacterial agent could be structurally enhanced to better suit clinical requirements.
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden. Electronic address: erik.unosson@angstrom.uu.se.
authors.forename: Erik
authors.initials: E
authors.lastname: Unosson
authors.affiliation: Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia, Avenida Diagonal 647, E08028 Barcelona, Spain; Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), E28029 Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rodriguez
authors.affiliation: Division of Nanotechnology and Functional Materials, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden.
authors.forename: Ken
authors.initials: K
authors.lastname: Welch
authors.affiliation: Division of Applied Materials Science, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Engqvist
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis* / Q000494:pharmacology*; D020650:Combinatorial Chemistry Techniques / Q000379:methods; D008422:Materials Testing; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D014025:Titanium / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; C009495:titanium dioxide; D012834:Silver; D014025:Titanium
keywords: Antibacterial; Combinatorial materials science; Physical vapor deposition; Silver; Titanium