Research Article Influence of the Microstructure and Silver Content on Degradation, Cytocompatibility, and Antibacterial Properties of Magnesium-Silver Alloys In Vitro Zhidan Liu, 1 Ronald Schade, 2 Bérengère Luthringer, 1 Norbert Hort, 1 Holger Rothe, 2 Sören Müller, 3 Klaus Liefeith, 2 Regine Willumeit-Römer, 1 and Frank Feyerabend 1 1 Institute for Material Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, 21502 Geesthacht, Germany 2 Institute for Bioprocessing and Analytical Measurement Techniques e.V. (iba), Rosenhof, 37308 Heilbad Heiligenstadt, Germany 3 Extrusion Research and Development Center, Chair Metallic Materials, TU Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany Correspondence should be addressed to Frank Feyerabend; frank.feyerabend@hzg.de Received 16 February 2017; Revised 28 April 2017; Accepted 8 May 2017; Published 22 June 2017 Academic Editor: Martin Kolisek Copyright © 2017 Zhidan Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Implantation is a frequent procedure in orthopedic surgery, particularly in the aging population. However, it possesses the risk of infection and biofilm formation at the surgical site. This can cause unnecessary suffering to patients and burden on the healthcare system. Pure Mg, as a promising metal for biodegradable orthopedic implants, exhibits some antibacterial effects due to the alkaline pH produced during degradation. However, this antibacterial effect may not be sufficient in a dynamic environment, for example, the human body. The aim of this study was to increase the antibacterial properties under harsh and dynamic conditions by alloying silver metal with pure Mg as much as possible. Meanwhile, the Mg-Ag alloys should not show obvious cytotoxicity to human primary osteoblasts. Therefore, we studied the influence of the microstructure and the silver content on the degradation behavior, cytocompatibility, and antibacterial properties of Mg-Ag alloys in vitro. The results indicated that a higher silver content can increase the degradation rate of Mg-Ag alloys. However, the degradation rate could be reduced by eliminating the precipitates in the Mg-Ag alloys via T4 treatment. By controlling the microstructure and increasing the silver content, Mg-Ag alloys obtained good antibacterial properties in harsh and dynamic conditions but had almost equivalent cytocompatibility to human primary osteoblasts as pure Mg. 1. Introduction The clinical application of biodegradable implant and pros- thesis has shown rapid growth to keep with the demands of a rapidly aging population. However, implant-associated orthopedic surgery infections are common postoperative wound infections and can cause biofilm formation on the implants or bones [1, 2]. Biofilms are resistant to antibiotics and can protect bacteria from host immune mechanisms. Once a biofilm has formed, the only treatment is to remove the implant and the diseased tissue [3–5]. Prevention is the preferred method to address the growing problem of implant-associated infections [6, 7]. Pure magnesium (pure Mg) and its alloys, as potential biodegradable implant materials, have the advantage of not requiring removal after bone tissue healing [8]. Therefore, infection caused by a second surgery can be avoided. In vitro, pure Mg exhibited some antibacterial properties due to its alkaline pH [9–11]. In the early stage of degradation, it can create an alkaline environment, which is adverse to the sur- vival and reproduction of bacteria [12, 13]. However, it is not clear whether these changes will occur in vivo, although it was shown that pure Mg induces osteoblasts and suppresses bacteria in a chronically infected rabbit tibial oste- omyelitis model [14]. However, the length of time that an effective antibacterial concentration maintained in the local position is not sufficient, which will influence the resistance to infection and will affect osteomyelitis treatment [14, 15]. One cause of these effects is that the degradation rate of pure Mg and magnesium alloys in vivo is lower than that in vitro Hindawi Oxidative Medicine and Cellular Longevity Volume 2017, Article ID 8091265, 14 pages https://doi.org/10.1155/2017/8091265