Finding order in chaos: scientists determine the structure of glass-shaping protein in sponges
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Publication: How sponges 'spike' themselves with glass
"In this paper, we describe the principles of morphogenesis of glass spicules in marine sponges from the class Demospongiae", explains Dr. Igor Zlotnikov, one of the authors of the publication. The spicules exhibit a large diversity of the most intricate and highly regular branched three-dimensional morphologies that are a paradigm example of symmetry in biological systems. This symmetry, obtained in an amorphous ceramic material at temperatures far below glass transition, still baffles the biomineralization community. Partly, because nature’s capacity to produce these extremely complex glass structures is far beyond the reach of current human technology. Our previous work showed that the organic axial filament that scaffolds the shape of the spicules is in fact a perfect single crystal made of proteins. These proteins (silicateins) are responsible for silica biomineralization. In this work, using data from three different X-ray imaging and analysis beamlines at the ESRF (nanotomography – ID16A, microtomography-ID19 and SAXS-ID13), we show that crystallographic branching of this protein crystal is responsible for the highly regular morphology of these naturally occurring glass structures. Using spicules with varying levels of structural complexity, from three different organisms, we demonstrate that the branching of the spicule follows specific crystallographic directions defined by the crystalline properties of the axial filament.
Moreover, we draw an analogy to a similar fabrication strategy employed by humankind to form nanocrystalline inorganic structures. In fact, analogous synthesis approach of highly regular branched inorganic single crystals for the use in solar cells, plasmonics, optoelectronics and sensing is currently a very active research area.
To summarize, our study reveals half a billion years old fabrication concept, employed by nature, that only recently has been used by man-kind to produce novel technologically relevant nanomaterials. It is also fascinating that both converged to a similar thermodynamically-driven fabrication method, independently.
Watch the video from Science Magazine: "How sponges 'spike' themselves with glass"
Shaping highly regular glass architectures: A lesson from nature
Vanessa Schoeppler, Elke Reich, Jean Vacelet, Martin Rosenthal, Alexandra Pacureanu, Alexander Rack, Paul Zaslansky, Emil Zolotoyabko, Igor Zlotnikov
Science Advances 18 Oct 2017, Vol. 3, no. 10, DOI: 10.1126/sciadv.aao2047
Figure 1: Electron microscopy image of the glass architecture of a sphere like spicule from the sponge Geodia cydonium.
Figure 2: Electron microscopy image of glass spicules form the sponge Geodia cydonium.
Figure 3: Electron microscopy image of star like spicules from the sponge Tethya aurantium.Back to News Ticker