Marine sponges’ glass skeletons offer tips for future electronics


Technology manufacturers have a thing or two to learn from the humble marine sponge, writes Michael Lucy.


Electron microscopy image of glass spicules from the sponge Geodia cydonium.
Electron microscopy image of glass spicules from the sponge Geodia cydonium.
Zlotnikov Group, B CUBE, TU Dresden

Modern electronics may take a lesson from some of the oldest organisms on the planet, following the discovery of how certain marine sponges develop their characteristic crystal-like spikes.

The sponges fabricate precisely shaped nanocrystals using a technique that could prove handy in making electronic devices from solar cells to sensors.

Their secret, according to a team of researchers led by Igor Zlotnikov of the Technical University of Dresden in Germany, lies in the way they use proteins.

The researchers studied three species of sponges (Thethyra aurantium, Stryphnus ponderosus, and Geodia cydonium) that use tiny, complex glass structures known as spicules as a kind of skeleton for internal support and increased strength and protection.

Electron microscopy image of star-like spicules from the sponge Tethya aurantium.
Electron microscopy image of star-like spicules from the sponge Tethya aurantium.
Zlotnikov Group, B CUBE, TU Dresden

Inside each spicule is a tiny filament containing a protein called silicatein, which together with some derivative proteins catalyses the deposition of silica. The spatial structure of these protein molecules, the researchers found, helps to determine the final shape of the spicule.

By using electron microscopes and X-ray diffraction to examine the spicules produced by the sponges, Schoeppler and her team found the proteins in the filaments are packed in a regular hexagonal crystalline structure. This was true for all three sponges, despite the fact they produce spicules in different shapes.

While T. aurantium produces straight, needle-like spicules, those of S. ponderosus exhibit precise three-way branching, and G. cydonium grows spiky orbs that mature into rough spheres.

Spicules from T. aurantium, S. ponderosus, and G. cydonium.
(A) Spicules from T. aurantium. Scale bar, 100 mm. Inset: Cross section of the spicule. (B) Spicule from S. ponderosus. (C to E) Spicules from G. cydonium at different maturation levels.
Schoeppler et al., Sci. Adv. 2017;3: eaao2047

The differing shapes of the spicules, however, can be explained by tiny variations in the spacing and arrangement of proteins. Because the protein filament acts as a template for the deposition of silica onto the spicule, very small differences in distance and angle can translate into larger-scale changes in branching and symmetry.

As the researchers note, we have plenty to learn from the abilities of these humble sponges, which are “far beyond the reach of current human technology”.

The research is published in Science Advances.

  1. http://advances.sciencemag.org/content/3/10/eaao2047
  2. http://advances.sciencemag.org/content/3/10/eaao2047
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