Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment

Xin, Yunchang; Huo, Kaifu; Hu, Tao; Tang, Guoyi; Chu, Paul K.

doi:10.1016/j.actbio.2008.05.014

Cited by 365 publications

(193 citation statements)

References 20 publications

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“…Pitting corrosion commonly occurs in metals that are protected by a passivation layer (e.g., Mg with a Mg(OH) 2 layer). [29][30][31][32] It is well known that chloride ions promote the corrosion of Mg in aqueous solutions. 31 Aggressive anionic species, such as chloride, are able to penetrate the passivation layer and are further electrostatically transported into the pit, where they serve to balance the charge within the corrosion pits as the Mg + cation concentration builds up.…”

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confidence: 99%

Seawater-driven magnesium based Janus micromotors for environmental remediation

et al. 2013

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We describe the use of seawater as fuel to propel Janus micromotors.The new micromotors consist of biodegradable and environmentally friendly magnesium microparticles and a nickel-gold bilayer patch for magnetic guidance and surface modification. Such seawaterdriven micromotors, which utilize macrogalvanic corrosion and chloride pitting corrosion processes, eliminate the need for external fuels to offer efficient and prolonged propulsion towards diverse applications in aquatic environments.The propulsion of synthetic nanoscale objects represents a great challenge and opportunity, and has thus stimulated considerable research efforts in recent years. 1-10 Self-propelled micromotors offer promise for diverse practical applications, such as drug delivery, 11,12 biomaterials isolation, 13-15 surface patterning 16 and environmental remediation. 17 Bubblepropelled catalytic micromotors are particularly attractive due to their efficient propulsion in relevant biological uids and high ionic-strength media. 18-21 Unfortunately, the requirement of the hydrogen peroxide fuel greatly impedes many practical applications of such catalytic micro/nanoscale motors. 7 New micro/nanomotors that can harvest energy from their own surrounding environment, i.e., use the sample matrix itself as their fuel source, are highly desired for eliminating the need for adding external fuels. For example, Gao et al. illustrated hydrogen-bubble-propelled micromotors that can be powered in acidic or alkaline media. 22,23 However, water is the obvious ideal choice of fuel for the majority of practical nanomachine applications compared to extreme acidic or alkaline media. Recently we described the rst example of a water-driven micromotor, based on Al/Ga microparticles, which displayed efficient propulsion in aqueous solutions. 24 However, due to the toxicity of aluminum and gallium, more biocompatible and environmentally friendly materials are highly desired for different applications of water-driven micromotors.Here we demonstrate a new hydrogen-bubble-propelled Janus micromotor, based on the magnesium-water reaction, which can be self-propelled in seawater without an external fuel. Common active metals (e.g., Li, Na, K, Ca), can lead to efficient hydrogen evolution from the water-metal reaction, but are too reactive for a safe operation and are not stable in air. Magnesium, in contrast, is an attractive candidate material for the design of water-driven micromotors as it is a biocompatible 'green' nutrient trace element, vital for many bodily functions and enzymatic processes. In addition, Mg is a low cost metal and Mg 2+ is present in different natural environments (e.g., seawater). The Mg-water reaction is commonly hindered in ambient atmospheres due to the formation of a compact hydroxide passivation surface layer. Accordingly, Mg cannot continuously reduce water to generate hydrogen bubbles. 25,26 However, we demonstrate in the following sections that the micromotor can display efficient and prolonged propulsion in chloride-rich environments ...

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Seawater-driven magnesium based Janus micromotors for environmental remediation

et al. 2013

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“…This reaction is presented in Equation (2). Increased concentration of Cl − was found to increase the probability for localised corrosion of AZ91 in a range of modified SBFs [59]. Cl − were also postulated to have destabilised the corrosion product layer, inducing the dissolution of the mildly protective Mg(OH) 2 layer and transforming it into a soluble MgCl 2 layer in CP-Mg samples [67].…”

Section: Chloride Ions (Cl − )mentioning

confidence: 99%

“…Corrosion rates are useful for a direct comparison between samples or alloys, however they may not provide a complete picture of the corrosion when considered on their own. Consideration of the corrosion morphology is also recommended, as this provides information on the type of corrosion that has occurred [42,59].…”

Section: Magnesium Corrosion Assessmentmentioning

confidence: 99%

“…In a simple NaCl solution the pH increases to~10.3 after several hours due to the low solubility of Mg(OH) 2 ; the physical chemistry by which the pH is controlled by the low solubility of Mg(OH) 2 is fully described by Atrens et al [55]. Xin et al [59] considered the influence of a range of ions, including HCO 3 − , on the corrosion of AZ91. The presence of HCO 3 − appeared to initially stimulate corrosion, before aiding passivation due to the precipitation of MgCO 3 and CaCO 3 , which slightly lowered the corrosion rate and completely supressed any incidence of localised corrosion.…”

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confidence: 99%

“…This result was supported by the results of Ma et al [67] who conducted a primarily electrochemical study of the biocorrosion of CP-Mg and also concluded that the presence of HCO 3 − initially increased the corrosion rate but eventually promoted the deposition of a protective corrosion layer which reduced the corrosion rate. However, these results [59,67] only provide a binary comparison between solutions with and without HCO 3 − . As previously discussed, HCO 3 − are an essential component to the buffer system shown in Equation (3).…”

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Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

2017

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The factors that influence magnesium (Mg) corrosion in vitro are systematically evaluated from a review of the relevant literature. We analysed the influence of the following factors on Mg biocorrosion in vitro: (i) inorganic ions, including both anions and cations, (ii) organic components such as proteins, amino acids and vitamins, and (iii) experimental parameters such as temperature, pH, buffer system and flow rate. Considerations and recommendations towards a standardised approach to in vitro biocorrosion testing are given. Several potential simulated body fluids are recommended. Implementing a standardised approach to experimental parameters has the potential to significantly reduce variability between in vitro biocorrosion tests, and to help build towards a methodology that accurately and consistently mimics in vivo corrosion. However, there are also knowledge gaps with regard to how best to characterise the in vivo environment and corrosion mechanism. The assumption that blood plasma is the correct bodily fluid upon which to base in vitro methodologies is examined, and factors that influence the corrosion mechanism in vivo, such as specimen encapsulation, bear consideration for further studies.

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Coating Systems for Magnesium‐Based Biomaterials ‐ State of the Art

Waterman¹,

Staiger²

2011

Magnesium Technology 2011

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Influence of aggressive ions on the degradation behavior of biomedical magnesium alloy in physiological environment

Cited by 365 publications

References 20 publications

Seawater-driven magnesium based Janus micromotors for environmental remediation

Seawater-driven magnesium based Janus micromotors for environmental remediation

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

Coating Systems for Magnesium‐Based Biomaterials ‐ State of the Art

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