Abstract

This work is a detailed study of the giant barnacle shell micro-nano-structure and the relationship between the organic matrix and the mineral. We have studied the composition of the organic matrix and how this interacts with the mineral part, controlling crystal orientation and modifying the nanostructure and crystal lattice. The incorporation of organic matter into the mineral produces a rough topography in the calcite crystals surface, reducing the size of coherent crystal domains and inducing an isotropic straining of the calcite crystal lattice (about 0.08% along the a- and c- axes). We show that insoluble organic matrixes are mainly chitin-rich membranes that can induce the nucleation of calcite crystals on their surface. Also, we have studied the effect of the soluble organic matter (composed of proteins and polysaccharides) on the calcium carbonate precipitation, inducing the formation of calcite, which is the only mineral phase present in the barnacle shell. It has an important effect on nucleation (reducing the number of crystals and promoting their aggregation). It also modifies the calcite morphology by the expression of prismatic crystals faces without interfering with epitaxial growth.