title: Development of nanosized silver-substituted apatite for biomedical applications: A review.
abstract: The favorable biocompatibility of hydroxyapatite (HA) makes it a popular bone graft material as well as a coating layer on metallic implant. To reduce implant-related infections, silver ions were either incorporated into the apatite during co-precipitation process (AgHA-CP) or underwent ion-exchange with the calcium ions in the apatite (AgHA-IE). However, the distribution of silver ions in AgHA-CP and AgHA-IE was different, thus affecting the antibacterial action. Several studies reported that nanosized AgHA-CP containing 0.5 wt.% of silver provided an optimal trade-off between antibacterial properties and cytotoxicity. Nevertheless, nanosized AgHA and AgHA nanocoatings could not function ideally due to the compromise in the bone differentiation of mesenchymal stem cells, as evidenced in the reduced alkaline phosphatase, type I collagen and osteocalcin. Preliminary studies showed that biological responses of nanosized AgHA and AgHA nanocoatings could be improved with the addition of silicon. This review will discuss on nanosized AgHA and AgHA nanocoatings.
  
  
  BACKGROUND
  In many patients needing bone graft material, hydroxyapatite (HA) has proven to be a popular choice. Nonetheless, implant-related infections remain a major concern. Hence, effective preventive measures are needed. In this review article, the authors discussed the application of incorporating silver nanoparticles in HA and its use as bone graft biomaterials together with the addition of silica.
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, Singapore.
authors.forename: Poon Nian
authors.initials: PN
authors.lastname: Lim
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, Singapore.
authors.forename: Lei
authors.initials: L
authors.lastname: Chang
authors.affiliation: Department of Mechanical Engineering, National University of Singapore, Singapore. Electronic address: mpetes@nus.edu.sg.
authors.forename: Eng San
authors.initials: ES
authors.lastname: Thian
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001031:Apatites / Q000737:chemistry* / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000648:ultrastructure; D053768:Metal Nanoparticles; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001031:Apatites; D012834:Silver
keywords: Antibacterial; Apatite; Nanosized; Silver