Our approach involves the use
of Fusarium oxysporum, a plant pathogenic fungus, in the
biotransformation of naturally occurring amorphous plant biosilica
into quasi-spherical crystalline silica nanoparticles and
its extracellular leaching in the aqueous environment at room
temperature. The silica biotransformation is fairly rapid and
occurs within 1 day of reaction of the fungal biomass with the
rice husk. It is interesting to note that, despite the in vitro studies
of various natural or synthetic macromolecules in this context,17-19
only the Fusarium oxysporum based system was able to produce
the aforesaid silica structures for the conditions studied to date.
In previous studies, we have demonstrated that Fusarium
oxysporum is an excellent microorganism for the biosynthesis of metal20 and metal oxide21 nanoparticles from their precursor
salts. Recently, we have also shown a fungus-based bioleaching
approach for the synthesis of hollow silica nanospheres from
sand,22 and the new results presented in this paper add
considerably to the potential for application of this versatile
fungus to nanotechnology, particularly in the development of
cheap, energy-conserving, eco-friendly methods for the largescale
synthesis of nanomaterials.