Aerogels have useful properties such as very low density and high thermal and sound insulation. Using a base material that acts as a reduction agent could allow the synthesis of inorganic nanoparticle directly on the aerogel surface, leading to new classes of aerogels for a wide range of applications.

Raffaele Mezzenga, ETH Zurich, Switzerland, and colleagues used this approach to synthesize aerogels functionalized with gold nanoparticles. The basis was an amyloid fibril framework, generated using milk protein. The amino acids on the surface of these protein nanofibrils act as reduction sites, and covert gold salt in solution into micro- or nanoparticles upon drying. The resulting product (pictured) contains roughly 80 % gold, but at a density 1000 times lower than conventional alloys.

The material could be used in place of gold alloys for many applications with substantially less weight and material cost, and might also open up new possibilties in catalysis due to its large surface area. It can also be used in pressure sensors, because it does not conduct eletricity in its normal state, but becomes conductive upon compression.

• Amyloid Templated Gold Aerogels,
  Gustav Nyström, María P. Fernández-Ronco, Sreenath Bolisetty, Marco Mazzotti, Raffaele Mezzenga,
  Adv. Mater. 2015.
  DOI: 10.1002/adma.201503465