Flexible Minerals: Self-Assembled Calcite Spicules with Extreme Bending Strength

• Autores: Filipe Natalio, Martin Panthöfer, Dieter Schollmeyer, Ingo Lieberwirth
• Localización: Science, ISSN 0036-8075, Vol. 339, Nº 6125, 2013, págs. 1299-1302
• Idioma: inglés
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• Resumen

  • Silicatein-α is responsible for the biomineralization of silicates in sponges. We used silicatein-α to guide the self-assembly of calcite "spicules" similar to the spicules of the calcareous sponge Sycon sp. The self-assembled spicules, 10 to 300 micrometers (μm) in length and 5 to 10 μm in diameter, are composed of aligned calcite nanocrystals. The spicules are initially amorphous but transform into calcite within months, exhibiting unusual growth along [100]. They scatter x-rays like twinned calcite crystals. Whereas natural spicules evidence brittle failure, the synthetic spicules show an elastic response, which greatly enhances bending strength. This remarkable feature is linked to a high protein content. With nano-thermogravimetric analysis, we measured the organic content of a single spicule to be 10 to 16%. In addition, the spicules exhibit waveguiding properties even when they are bent.