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Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm

DOI: 10.1016/j.bioactmat.2021.04.009 DOI Help

Authors: Berit Zeller-Plumhoff (Helmholtz-Zentrum Hereon) , Daniel Laipple (Helmholtz-Zentrum Hereon) , Hanna Slominska (Helmholtz-Zentrum Hereon) , Kamila Iskhakova (Helmholtz-Zentrum Hereon) , Elena Longo (Helmholtz-Zentrum Hereon) , Alexander Hermann (Helmholtz-Zentrum Hereon) , Silja Flenner (Helmholtz-Zentrum Hereon) , Imke Greving (Helmholtz-Zentrum Hereon) , Malte Storm (Diamond Light Source) , Regine Willumeit-Römer (Helmholtz-Zentrum Hereon)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Bioactive Materials , VOL 6 , PAGES 4368 - 4376

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 22346 , 21697

Open Access Open Access

Abstract: Magnesium is attractive for the application as a temporary bone implant due to its inherent biodegradability, non-toxicity and suitable mechanical properties. The degradation process of magnesium in physiological environments is complex and is thought to be a diffusion-limited transport problem. We use a multi-scale imaging approach using micro computed tomography and transmission X-ray microscopy (TXM) at resolutions below 40 nm. Thus, we are able to evaluate the nanoporosity of the degradation layer and infer its impact on the degradation process of pure magnesium in two physiological solutions. Magnesium samples were degraded in simulated body fluid (SBF) or Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS) for one to four weeks. TXM reveals the three-dimensional interconnected pore network within the degradation layer for both solutions. The pore network morphology and degradation layer composition are similar for all samples. By contrast, the degradation layer thickness in samples degraded in SBF was significantly higher and more inhomogeneous than in DMEM+10%FBS. Distinct features could be observed within the degradation layer of samples degraded in SBF, suggesting the formation of microgalvanic cells, which are not present in samples degraded in DMEM+10%FBS. The results suggest that the nanoporosity of the degradation layer and the resulting ion diffusion processes therein have a limited influence on the overall degradation process. This indicates that the influence of organic components on the dampening of the degradation rate by the suppression of microgalvanic degradation is much greater in the present study.

Journal Keywords: Magnesium degradation; Porosity; Transmission X-ray microscopy; 3D imaging

Diamond Keywords: Bone; Alloys

Subject Areas: Biology and Bio-materials

Instruments: I13-2-Diamond Manchester Imaging

Other Facilities: P05 at PETRA III at DESY


Discipline Tags:

Life Sciences & Biotech Health & Wellbeing Material Sciences Biomaterials

Technical Tags:

Imaging Tomography