title: Buffer-regulated biocorrosion of pure magnesium.
abstract: Magnesium (Mg) alloys are being actively investigated as potential load-bearing orthopaedic implant materials due to their biodegradability in vivo. With Mg biomaterials at an early stage in their development, the screening of alloy compositions for their biodegradation rate, and hence biocompatibility, is reliant on cost-effective in vitro methods. The use of a buffer to control pH during in vitro biodegradation is recognised as critically important as this seeks to mimic pH control as it occurs naturally in vivo. The two different types of in vitro buffer system available are based on either (i) zwitterionic organic compounds or (ii) carbonate buffers within a partial-CO(2) atmosphere. This study investigated the influence of the buffering system itself on the in vitro corrosion of Mg. It was found that the less realistic zwitterion-based buffer did not form the same corrosion layers as the carbonate buffer, and was potentially affecting the behaviour of the hydrated oxide layer that forms on Mg in all aqueous environments. Consequently it was recommended that Mg in vitro experiments use the more biorealistic carbonate buffering system when possible.
authors.affiliation: Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: Kirkland
authors.forename: Jay
authors.initials: J
authors.lastname: Waterman
authors.forename: Nick
authors.initials: N
authors.lastname: Birbilis
authors.forename: George
authors.initials: G
authors.lastname: Dias
authors.forename: Tim B F
authors.initials: TB
authors.lastname: Woodfield
authors.forename: Richard M
authors.initials: RM
authors.lastname: Hartshorn
authors.forename: Mark P
authors.initials: MP
authors.lastname: Staiger
mesh_terms: D000497:Alloys; D001672:Biocompatible Materials / Q000737:chemistry; D001673:Biodegradation, Environmental; D001826:Body Fluids; D002021:Buffers; D002244:Carbon / Q000737:chemistry; D003343:Corrosion; D003362:Cost-Benefit Analysis; D003470:Culture Media / Q000737:chemistry; D005740:Gases; D006801:Humans; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D009985:Orthopedics; D010949:Plasma / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D002021:Buffers; D003470:Culture Media; D005740:Gases; D002244:Carbon; D006859:Hydrogen; D008274:Magnesium