Biomimetic processes through the study of mineralized shells

Fabrication of mineralized structures is a widespread phenomenon among living organisms (e.g., shells, carapaces, spines, spicules, bones and teeth). These ceramic biocomposites consist of layered assemblies of minute amounts of macromolecules with well-ordered calcium-rich inorganic phases, resulting in the formation of products of unique morphologies and properties. The characterization of the mechanisms controlling the processes of biomineralization is crucial for the development of novel materials with desirable shape and texture properties. In previous reports on eggshells and mollusk and crustacean shells, we have studied the cell-shell interactions, the crystalline microstructure of the inorganic component, the localization of particular macromolecules and the capacity of various biomolecules to affect crystallization. Based on these comparative data, we propose that biomineralization can be described as a four-step process: (1) substrate fabrication, (2) crystal nucleation on the substrate or framework, (3) crystal growth in a gel and (4) mineralization arrest. These four steps open a new field for designing synthetic processes in order to fabricate new bioinspired composites with desirable properties. (C) 2003 Elsevier Inc. All rights reserved.