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Free keywords:
goethite; limpet radula; biomineralization; chitin; composite material; nucleation and growth; mollusks; hard biominerals; mechanically reinforced biomaterials; templated crystallization
Abstract:
Goethite is the most widespread iron oxide in natural environments. Limpets use goethite as a reinforcement material to form hard and wear-resistant teeth. These are used as scraping tools to extract bacteria and algae from rocks. Over the years, their remarkable mechanical properties have motivated intensive research on the biomineralization of limpet teeth, with a view to extract the underlying principles and use them in bio-inspired synthetic strategies of wear-resistant materials. It is, however, not goethite alone, which is responsible for the mechanical properties of the limpet teeth. Instead, the hierarchical organic–mineral composite structure gives rise to the observed mechanical properties. Moreover, the organic component is strongly involved in the biogenic formation of goethite crystals. The formation of goethite, the composite structure of teeth, and their mechanical properties are hence entangled. This chapter therefore attempts to address the biologically controlled crystallization of goethite in a holistic manner. We begin with an introduction to the anatomy of limpet radular teeth, followed by a brief summary of facts about the features of synthetically produced goethite. In continuation, we present an overview of findings about the goethite produced by limpets. Finally, we discuss some open questions, which still need to be clarified in order to get a complete understanding of goethite biomineralization in limpet teeth.
