CHAPTER 4: Advanced Transmission Electron Microscopy to Explore Early Stages of Bio(mimetic)mineralization

Understanding biomineralization is one of the great challenges of our scientific community. Where biological systems are complex and difficult to study at the molecular or (sub)nanometre level, simplified in vitro models have been successfully applied to gain further mechanistic insights and provide important guidelines for bio‐inspired materials synthesis. However, such insights can only be obtained through the use of techniques that are able to provide information on the dynamics of interaction between the organic and inorganic phases at the (sub‐)nanometre level. After discussing recent new mechanistic insights in bio(mimetic) mineralization and techniques that can provide information on the early stages of mineral formation, we focus on the use of TEM and TEM‐related techniques (diffraction, EDX, EELS) for the study of biominerals and biomimetic mineral formation, also addressing tomography for 3D imaging. Conventional TEM techniques – which require drying of the sample – cannot provide information on the dynamics of mineralization processes. In contrast, using cryogenic TEM (cryoTEM) and cryo‐electron tomography samples can be studied in their native hydrated state, which recently allowed the visualization of new ‘non‐classical’ mineralization pathways. Also the use of in situ TEM has recently opened new possibilities to obtain a deeper understanding of bio(mimetic) mineralization.