title: Controlling initial biodegradation of magnesium by a biocompatible strontium phosphate conversion coating.
abstract: A simple strontium phosphate (SrP) conversion coating process was developed to protect magnesium (Mg) from the initial degradation post-implantation. The coating morphology, deposition rate and resultant phases are all dependent on the processing temperature, which determines the protective ability for Mg in minimum essential medium (MEM). Coatings produced at 80 °C are primarily made up of strontium apatite (SrAp) with a granular surface, a high degree of crystallinity and the highest protective ability, which arises from retarding anodic dissolution of Mg in MEM. Following 14 days' immersion in MEM, the SrAp coating maintained its integrity with only a small fraction of the surface corroded. The post-degradation effect of uncoated Mg and Mg coated at 40 and 80 °C on the proliferation and differentiation of human mesenchymal stem cells was also studied, revealing that the SrP coatings are biocompatible and permit proliferation to a level similar to that of pure Mg. The present study suggests that the SrP conversion coating is a promising option for controlling the early rapid degradation rate, and hence hydrogen gas evolution, of Mg implants without adverse effects on surrounding cells and tissues.
authors.affiliation: Department of Materials Engineering, Monash University, VIC 3800, Australia. Electronic address: xiaobo.chen@monash.edu.
authors.forename: X B
authors.initials: XB
authors.lastname: Chen
authors.affiliation: Research School of Engineering, The Australian National University, Acton, ACT 0200, Australia; John Curtins School of Medical Research, The Australian National University, Acton, ACT 0200, Australia.
authors.forename: D R
authors.initials: DR
authors.lastname: Nisbet
authors.affiliation: The Medical School, The Australian National University, Acton, ACT 0200, Australia; John Curtins School of Medical Research, The Australian National University, Acton, ACT 0200, Australia.
authors.forename: R W
authors.initials: RW
authors.lastname: Li
authors.affiliation: The Medical School, The Australian National University, Acton, ACT 0200, Australia; John Curtins School of Medical Research, The Australian National University, Acton, ACT 0200, Australia.
authors.forename: P N
authors.initials: PN
authors.lastname: Smith
authors.affiliation: Department of Materials Engineering, Monash University, VIC 3800, Australia.
authors.forename: T B
authors.initials: TB
authors.lastname: Abbott
authors.affiliation: Department of Materials Engineering, Monash University, VIC 3800, Australia.
authors.forename: M A
authors.initials: MA
authors.lastname: Easton
authors.affiliation: Department of Anaesthesiology, The Second Hospital, Shandong University, Jinan 250033, China.
authors.forename: D-H
authors.initials: DH
authors.lastname: Zhang
authors.affiliation: Department of Materials Engineering, Monash University, VIC 3800, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Birbilis
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D003470:Culture Media; D055664:Electrochemical Techniques; D006801:Humans; D006859:Hydrogen / Q000032:analysis; D008274:Magnesium / Q000494:pharmacology*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis / Q000187:drug effects; D010710:Phosphates / Q000494:pharmacology*; D056951:Photoelectron Spectroscopy; D013324:Strontium / Q000494:pharmacology*; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D020099:Coated Materials, Biocompatible; D003470:Culture Media; D010710:Phosphates; D006859:Hydrogen; C052774:strontium phosphate; D000469:Alkaline Phosphatase; D008274:Magnesium; D013324:Strontium
keywords: Biodegradation; Conversion coatings; Human mesenchymal stem cells; Magnesium; Strontium phosphate