Advanced imaging techniques in biomineralisation research

Mineralisation in the context of organic matrices is a key process in many biological systems across kingdoms. Examples include the formation of marine microalgal cell walls and mollusc shells, as well as the skeletons and teeth of vertebrates. Experimental and theoretical work in this field dates back to the 19th century and has increasingly gained importance in such diverse areas as environmental protection, biomedicine and bio-inspired materials design, as well as heritage science.

Rooted in classical theories of phase separation and crystal growth, our understanding of mineral nucleation and growth has tremendously improved in the past 30 years, mainly due to the advancement of imaging and spectroscopy, materials synthesis and computational methods. Yet, many unresolved fundamental questions remain at the core of this research area, which can be addressed by advanced microscopy and spectroscopy techniques, allowing for unprecedented three-dimensional time and space resolution, using visible light, X-rays and electrons. The progress in electron and optical microscopy together with advances in analytical techniques in conjunction with imaging have made it possible to gain information not only of the atomic level structure of mineral/organic composites, but also their chemical composition and higher-level organisation. Further, there is an increasing interest in using these characterisation techniques to dynamically investigate mineralisation events with a variety of in situ methods in conjunction with powerful imaging and spectroscopy methods (e.g., liquid cell transmission electron microscopy, Raman spectroscopy, wide and small angle X-ray scattering, nano-diffraction). At the same time, the development of in situ methods and cryogenic imaging techniques that enable the study of biological samples in quasi-native environments and the preservation of transient mineral phases is rapidly evolving.

It becomes increasingly clear that the relationship between structure and function of hierarchical biominerals can only be understood by connecting the length scales and interrogating comprehensively the impact of atomic-level organisation and the multi-level assembly of the resulting composites. Hence, this Faraday Discussion focused on the application of advanced methods to scrutinise existing paradigms in biomineralisation research and improve our understanding of mineralisation processes in biological and bioinspired systems. To achieve this, the meeting brought together different communities, including world-leading experts in imaging and spectroscopy techniques, with the biomineralisation community where these methods are commonly used. Recent major breakthroughs in multiple imaging techniques in conjugation with the development of large-scale data analysis tools, which are especially relevant for this interdisciplinary research field, made this meeting timely; it provided a platform for discussions concentrating on exploring and exploiting these novel imaging and spectroscopy techniques across different length scales. The impressive quality of the papers published as a result of this Faraday Discussion reflects the vibrant and fruitful conversation throughout the meeting, which we hope will inspire a future continuation of this cross-disciplinary exchange.

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