CHAPTER 3: Understanding Hierarchy and Functions of Bone Using Scanning X‐ray Scattering Methods Check Access

Biological materials are often hierarchically structured from the nanometre to the macroscopic scale. Specific characterization methods are needed to characterize the structures at these different length scales. This chapter reviews, based on the example of bone, the use of X‐ray scattering methods to explore representative and quantitative structure information as well as structure–function relations in hierarchically structured biological materials. X‐ray scattering techniques are particularly well suited for the characterization of the form and ordering of organic as well as inorganic components in those materials. When nanometre‐sized structures are exposed to X‐rays, details on the internal material structure can be revealed by the analysis of the resulting interference patterns. Based on the example of bone, fundamental aspects of wide‐ and small‐angle X‐ray scattering (WAXS and SAXS) are discussed and examples how to apply these techniques are presented. By the use of scanning SAXS (sSAXS), i.e. moving the specimen step by step across a narrow X‐ray beam and collecting a SAXS pattern at each step, also specimen areas much larger than the beam size can be analysed. Furthermore, X‐ray scattering techniques can be combined with simultaneously performed mechanical experiments, which allows the investigation of the changes in structure resulting from external forces. To visualize the internal structure of biological materials also full‐field X‐ray methods are well suited. One example is X‐ray dark‐field imaging where the image contrast is formed through the mechanism of small‐angle scattering.