Development of a Bioreactor-Coupled Flow-Cell Setup for 3D In Situ Nanotomography of Mg Alloy Biodegradation

Functional materialsfeature hierarchical microstructures thatdefine their unique set of properties. The prediction and tailoringof these require a multiscale knowledge of the mechanistic interactionof microstructure and property. An important material in this respectis biodegradable magnesium alloys used for implant applications. Tocorrelate the relationship between the microstructure and the nonlineardegradation process, high-resolution in situ three-dimensional(3D) imaging experiments must be performed. For this purpose, a novelexperimental flow cell is presented which allows for the insitu 3D-nano imaging of the biodegradation process of materialswith nominal resolutions below 100 nm using nanofocused hard X-rayradiation from a synchrotron source. The flow cell setup can operateunder adjustable physiological and hydrodynamic conditions. As a modelmaterial, the biodegradation of thin Mg-4Ag wires in simulated bodyfluid under physiological conditions and a flow rate of 1 mL/min isstudied. The use of two full-field nanotomographic imaging techniques,namely transmission X-ray microscopy and near-field holotomography,is compared, revealing holotomography as the superior imaging techniquefor this purpose. Additionally, the importance of maintaining physiologicalconditions is highlighted by the preliminary results. Supporting measurementsusing electron microscopy to investigate the chemical compositionof the samples after degradation are performed.

Automated summary

Functional materials with hierarchical microstructures have unique properties that require an understanding of the mechanistic interaction between microstructure and property. In this study, a novel experimental flow cell was developed for in-situ 3D-nano imaging of the biodegradation process of biodegradable magnesium alloys. The importance of maintaining physiological conditions and the comparison of two imaging techniques were highlighted.