title: Antibacterial abilities and biocompatibilities of Ti-Ag alloys with nanotubular coatings.
abstract: OBJECTIVE
  To endow implants with both short- and long-term antibacterial activities without impairing their biocompatibility, novel Ti-Ag alloy substrates with different proportions of Ag (1, 2, and 4 wt% Ag) were generated with nanotubular coverings (TiAg-NT).
  
  
  METHODS
  Unlike commercial pure Ti and titania nanotube, the TiAg-NT samples exhibited short-term antibacterial activity againstStaphylococcus aureus(S. aureus), as confirmed by scanning electron microscopy and double staining with SYTO 9 and propidium iodide. A film applicator coating assay and a zone of inhibition assay were performed to investigate the long-term antibacterial activities of the samples. The cellular viability and cytotoxicity were evaluated through a Cell Counting Kit-8 assay. Annexin V-FITC/propidium iodide double staining was used to assess the level of MG63 cell apoptosis on each sample.
  
  
  RESULTS
  All of the TiAg-NT samples, particularly the nanotube-coated Ti-Ag alloy with 2 wt% Ag (Ti2%Ag-NT), could effectively inhibit bacterial adhesion and kill the majority of adheredS. aureuson the first day of culture. Additionally, the excellent antibacterial abilities exhibited by the TiAg-NT samples were sustained for at least 30 days. Although Ti2%Ag-NT had less biocompatibility than titania nanotube, its performance was satisfactory, as demonstrated by the higher cellular viability and lower cell apoptosis rate obtained with it compared with those achieved with commercial pure Ti. The Ti1%Ag-NT and Ti4%Ag-NT samples did not yield good cell viability.
  
  
  CONCLUSIONS
  This study indicates that the TiAg-NT samples can prevent biofilm formation and maintain their antibacterial ability for at least 1 month. Ti2%Ag-NT exhibited better antibacterial ability and biocompatibility than commercial pure Ti, which could be attributed to the synergistic effect of the presence of Ag (2 wt%) and the morphology of the nanotubes. Ti2%Ag-NT may offer a potential implant material that is capable of preventing implant-related infection.
authors.affiliation: Department of Orthopedics, The People's Hospital of China Medical University.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological Utilization Technology and Boron Materials, Northeastern University.
authors.forename: Ang
authors.initials: A
authors.lastname: Tian
authors.affiliation: School of Materials Science and Engineering, Shenyang University of Technology.
authors.forename: Junhua
authors.initials: J
authors.lastname: You
authors.affiliation: Department of Sports Medicine and Joint Surgery, The First Affiliated Hospital of China Medical University.
authors.forename: Hangzhou
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Orthopedics, The People's Hospital of China Medical University.
authors.forename: Xizhuang
authors.initials: X
authors.lastname: Bai
authors.affiliation: Department of Orthopedics, The People's Hospital of China Medical University.
authors.forename: Zeming
authors.initials: Z
authors.lastname: Lei
authors.affiliation: Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological Utilization Technology and Boron Materials, Northeastern University.
authors.forename: Xiaoguo
authors.initials: X
authors.lastname: Shi
authors.affiliation: Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological Utilization Technology and Boron Materials, Northeastern University.
authors.forename: Xiangxin
authors.initials: X
authors.lastname: Xue
authors.affiliation: Department of Sports Medicine and Joint Surgery, The First Affiliated Hospital of China Medical University.
authors.forename: Hanning
authors.initials: H
authors.lastname: Wang
mesh_terms: D000497:Alloys / Q000737:chemistry / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D043942:Nanotubes / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; D012834:Silver; D014025:Titanium
keywords: antibacterial; biocompatibility; nanotube; silver; titanium