One cell to make them all – Elucidating the origin of polymorphism and micro-structure diversity in biomineralization from pearl investigati

We aim at deciphering the physico-chemical mechanisms at play during biomineralization, exploiting the unique growth specificity of pearls. While pearls present complex structures (CaCO3 polymorphs and micro-structures), they form in a single, enclosed cellular environment, the pearl sac, which produces a set of organic molecules and controls the physico-chemical parameters of the media. From a previous 3D ptycho tomo experiment, we already obtained the 3D density distribution of a full pearl sample set. Here, we want to map out, in the very same samples, the 3D crystalline properties with x-ray nanodiffraction. This shall provide a unique mean to assess the recently proposed oriented solidification micro-structural growth model. Using 3D bragg ptychography, we will further identify the nature of the crystalline transition, in the different micro-structures, and compare it to recent crystallisation models, finally enabling new synthetic routes for bioinspired hierarchical materials.