Chemical speciation of nanoparticles surrounding metal-on-metal hips

Abstract

Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed.

Correlative electron and X-ray microscopy: probing chemistry and bonding with high spatial resolution

“…14 A typical spectral resolving power or monochromaticity (defined as E/ΔE) is ~5000, which corresponds to an energy resolution of 60 meV at the carbon K edge for example, or 140 meV at the iron L 2,3 edge. [15][16][17] These values are below the natural widths of core loss spectra, 18 enabling detailed 40 fine structure in the near edge region to be adequately resolved. In this situation, the principle reason to pay attention to energy resolution in the STXM is to enable meaningful comparisons between spectra measured at different facilities.…”

“…25,33 Suenaga et al demonstrated that even single-atom detection is achievable using STEM-EELS (figure 3 a-c). Using a model system of Gd-metallofullerene molecules trapped within a single walled nanotube (SWNT), individual Gd atoms were mapped using the Gd N edge, though counting 40 statistics were understandably low. 22 In a more recent study, Ramasse et al 23 were able to obtain EEL spectra over individual substitutional Si atoms in graphene, and observed changes in fine structure for different defect geometries (figure 3 d,e).…”

“…These examples demonstrate that combining high resolution STEM-EELS with spatially-averaged XAS is a powerful approach which can provide a more complete characterisation of the structure and chemistry of nanoscale 15 systems. The addition of STXM-XAS to a correlative study of CoCrMo nanoparticles from metal-on-metal hip prostheses 40 allowed oxidised and metallic Co signatures to be spatially resolved, showing that they arose from distinct wear particles (figure 4 c-i). Improved spatial resolution from STEM-EELS measurements allowed the elemental distribution to be determined across 35 individual nanoparticles, and evidence of a core-shell structure in which metallic particles were surrounded by an oxygen-rich, cobalt-depleted layer was observed.…”

“…To explore how the addition of spatially-resolved XAS measurements can further benefit nanoscale characterisation, we 40 consider a number of studies on nitrogen-doped carbon nanotube (N-CNT) systems. Nitrogen doping is performed either to tailor electrical properties of the CNTs themselves, or as a means of storing nitrogen gas.…”

“…These spectroscopies study the 35 primary processes of inelastic electron scattering or X-ray absorption to obtain chemical information, from chemical speciation analysis to local bonding environments and electronic structure. While the secondary process of X-ray emission also provides chemical information in the electron and X-ray 40 microscopes (by energy dispersive X-ray spectroscopy and X-ray probe X-ray micro-and nano-analysis respectively), these techniques, whilst being very sensitive to low concentrations, are limited to elemental analysis, and they will not be discussed in this review. Although the probe-specimen interactions of EELS 45 and XAS differ (electron scattering and photon absorption, respectively), they provide remarkably similar chemical information.…”