Transformation/dissolution studies on the release of iron and chromium from particles of alloys compared with their pure metals and selected metal oxides

Wallinder

2013

J Biomed Mater Res

The objective of this study was to investigate the extent of released Co, Cr(III), Cr(VI), and Mo from a biomedical high-carbon CoCrMo alloy exposed in phosphate-buffered saline (PBS), without and with the addition of 10 µM H2 O2 (PBS + H2 O2 ), and 10 g L(-1) bovine serum albumin (PBS + BSA) for time periods up to 28 days. Comparative studies were made on AISI 316L for the longest time period. No Cr(VI) release was observed for any of the alloys in either PBS or PBS + H2 O2 at open-circuit potential (no applied potential). However, at applied potentials (0.7 V vs. Ag/AgCl), Cr was primarily released as Cr(VI). Co was preferentially released from the CoCrMo alloy at no applied potential. As a consequence, Cr was enriched in the utmost surface oxide reducing the extent of metal release over time. This passivation effect was accelerated in PBS + H2 O2 . As previously reported for 316L, BSA may also enhance metal release from CoCrMo. However, this was not possible to verify due to the precipitation of metal-protein complexes with reduced metal concentrations in solution as a consequence. This was particularly important for Co-BSA complexes after sufficient time and resulted in an underestimation of metals in solution.

Section: Discussionmentioning

confidence: 92%

Metal release and speciation of released chromium from a biomedical CoCrMo alloy into simulated physiologically relevant solutions

Wallinder

2013

J Biomed Mater Res

“…3. Strongly decreasing metal release rates with time are typical for stainless steels in most media [6–8, 31, 38, 39, 41, 46]. This is explained by the initial dissolution and repassivation of instable phases and defects on the surface, and by the passivation of the surface, e.g.…”

Section: Resultsmentioning

confidence: 99%

“…The stabilities of chromium and iron oxides are very different and also pH dependent. At acidic, neutral or weakly alkaline pH, Fe 2 O 3 is more soluble compared with Cr 2 O 3 [38, 39]. However synergistic and/or antagonistic effects in the mixed oxide layer may result in a completely different dissolution behavior.…”

Section: Resultsmentioning

confidence: 99%

Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release

Wang

et al. 2013

J Mater Sci: Mater Med

Self Cite

109

141

Implantation using stainless steels (SS) is an example where an understanding of protein-induced metal release from SS is important when assessing potential toxicological risks. Here, the protein-induced metal release was investigated for austenitic (AISI 304, 310, and 316L), ferritic (AISI 430), and duplex (AISI 2205) grades in a phosphate buffered saline (PBS, pH 7.4) solution containing either bovine serum albumin (BSA) or lysozyme (LSZ). The results show that both BSA and LSZ induce a significant enrichment of chromium in the surface oxide of all stainless steel grades. Both proteins induced an enhanced extent of released iron, chromium, nickel and manganese, very significant in the case of BSA (up to 40-fold increase), whereas both proteins reduced the corrosion resistance of SS, with the reverse situation for iron metal (reduced corrosion rates and reduced metal release in the presence of proteins). A full monolayer coverage is necessary to induce the effects observed.Electronic supplementary materialThe online version of this article (doi:10.1007/s10856-013-4859-8) contains supplementary material, which is available to authorized users.

“…Elaborate studies have been performed generating data on release, dissolution, and solubility aspects of chromium and chromium-containing alloys such as stainless steels and ferrochromium alloys [1][2][3][4][5][6][7][8][9], data that has been utilised within the framework of the European chemicals legislation (REACH) implemented in 2007. Bioaccessibility and environmental impact aspects of chromium have been discussed by, for example, [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Chemical Stability of Chromium Carbide and Chromium Nitride Powders Compared with Chromium Metal in Synthetic Biological Solutions

2012

Chromium carbide (Cr-C) and chromium nitride (Cr-N) powders were compared with a chromium metal powder (Cr-metal) to evaluate their chemical stability in solution. All three powders were exposed in five different synthetic biological solutions of varying pH and chemical composition simulating selected human exposure conditions. Characterisation of the powders, using GI-XRD, revealed that the predominant bulk crystalline phases were Cr7C3 and Cr2N for Cr-C and Cr-N respectively. The outermost surface of Cr-C, determined by XPS, contained Cr7C3 and Cr2O3 and the corresponding measurement on Cr-N revealed Cr2N and CrN apart from Cr2O3. The presence of Cr2O3 was verified by XPS investigations of the Cr-metal powder. The mean particle size was similar for Cr-metal and Cr-N but slightly smaller for Cr-C. All three powders were poorly soluble and released very low amounts of chromium (<0.00015 μg Cr/μg loaded particles) independent on test solution. Slightly higher chromium concentrations were determined in the more acidic media (pH 1.7 and 4.5) compared with the near-neutral solutions (pH 7.2 and 7.4). Cr-C released the lowest amount of Cr despite having the largest surface area a feature attributed to the strong covalent bonds within the matrix.