Press Release
Angewandte Chemie International Edition 2008, 47, 7876–7879 doi: 10.1002/anie.200801802 Nr. 36/2008 Noble FungiNoble metal nanoparticles deposit on the mycelium of growing fungi—an approach to new catalytic systems?Contact: Alexander Eychmüller, Technische Universität Dresden (Germany) Registered journalists may download the original article here: Fungal Templates for Noble-Metal Nanoparticles and Their Application in Catalysis When fungi, such as penicillium, grow, they form a thread-like network,
the mycelium. If the fungus is grown in a medium containing nanoscopic
particles of a noble metal, the resulting mycelium is coated with the
nanoparticles. As researchers from the Technical University in Dresden
and the Max Planck Institute for the Chemical Physics of Solid Materials
in Dresden (Germany) report in the journal Angewandte Chemie,
such hybrids could be an interesting new approach for the production of
catalytic systems.
The team, led by Alexander Eychmüller and Karl-Heinz Pée, cultivated
various types of fungus in media with finely divided (colloidal)
nanoparticles of noble metals. In the presence of the tiny gold,
platinum, or palladium particles, the fungi grew with no appreciable
impairment. Silver particles, which are toxic to microorganisms, were
also tolerated by one variety of fungus. The nanoparticles are deposited
on the surface of the growing mycelium—without any special modification
beforehand. Thus hybrid systems made of fungi and noble metals are formed:
tubular hyphae covered in multiple layers of individual nanoparticles.
The optical properties of nanoscopic particles depend on their size. The
researchers determined that the optical properties of their deposited
particles differ only slightly from those of the nanoparticles in
solution. Fungal threads with a 0.2µm gold covering thus appear reddish
brown, like a solution of such gold nanoparticles. This is evidence that
the nanoparticles have not aggregated to form larger units.
Because the particles remain separate, the mycelium-bound noble metal
nanoparticles should also retain their special catalytic activities. The
researchers were thus able to determine that a platinum–fungus hybrid
catalyzes the redox reaction of hexacyanoferrate and thiosulfate in
aqueous solution. The “enobled” fungal mycelium offers a system easy to
separate from the solution after the reaction and a highly specific
surface—important for a catalyst.
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