title: Phosphate chemical conversion coatings on metallic substrates for biomedical application: a review.
abstract: Phosphate chemical conversion (PCC) technology has been investigated for improving the surface performance of metallic implants in the biomedical field over the last decade. The metallic materials, such as magnesium and its alloys, titanium, pure iron and stainless steel are widely used as orthopedic devices for immobilization of bone fractures in clinic. They were previously studied as metal substrates for PCC coating aiming to modify their biocompatibility and osteoconductivity. Zinc, calcium and zinc-calcium PCC coatings are frequently utilized considering their nature and the end-use. Although PCC coating has been confirmed to potentially improve the bio-performance of metallic implants in vitro and in vivo by many researchers, there are no unified standards or regulations to give quantitative appraisal of its quality and property. As such, an overview of several main phosphate phases together with their properties and behaviors in vitro and in vivo was conducted. The mechanism of phosphating was also briefly discussed. Critical qualities of PCC coating used for biomedical application including corrosion resistance, wettability and bonding strength were analyzed separately. Biological response including in vitro cell investigations and in vivo tissue response were discussed in terms of the cytocompatibility and bioactivity of PCC coating. Further investigations are proposed to develop appropriate performance evaluation measurements by combining conventional technologies and biomedical procedures.
authors.affiliation: Suzhou Institute, Shandong University, Suzhou 215123, China; Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji'nan 250061, China; School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.affiliation: Suzhou Institute, Shandong University, Suzhou 215123, China; Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji'nan 250061, China; School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Suzhou Institute, Shandong University, Suzhou 215123, China; Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji'nan 250061, China; School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China.
authors.forename: Gui-yong
authors.initials: GY
authors.lastname: Xiao
authors.affiliation: Suzhou Institute, Shandong University, Suzhou 215123, China; Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Ji'nan 250061, China; School of Materials Science and Engineering, Shandong University, Ji'nan 250061, China. Electronic address: biosdu@sdu.edu.cn.
authors.forename: Yu-peng
authors.initials: YP
authors.lastname: Lu
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible; D066298:In Vitro Techniques; D008670:Metals / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry*; D011817:Rabbits; D017155:Wettability
chemical_list: D020099:Coated Materials, Biocompatible; D008670:Metals; D010710:Phosphates
keywords: Biological response; Conversion coating; Phase; Phosphate; Quality