Saturday, 21 August 2010

Mountain ash alchemy

The Finns are at it again.  Not content with making an intoxicating drink from Sorbus berries, they are now using an extract of the leaves to obtain gold a silver nano particles:

Bioprospective of Sorbus aucuparia leaf extract in development of silver and gold nanocolloids

by Shashi Prabha Dubey, Manu Lahtinen, Heikki Särkkä and Mika Sillanpää in Science Direct (2010).


At the present time the bioprospective field is a  dynamic area of research. The rapid biosynthesis of silver and gold nanoparticles without using toxic chemicals is reported here. Sorbus aucuparia is omnipresent in Europe. The aqueous leaves extract of the plant were used as reducing agent for the synthesis of silver and gold nanoparticles from their salt solutions. The synthesized nanoparticles were spherical, triangular and hexagonal in shape with an average size of 16 and 18 nm for silver and gold, respectively. Different extract quantities, metal concentrations, temperatures and contact times were investigated to find their effect on nanoparticles synthesis. The resulting silver and gold nanoparticles were characterized by transmission electron microscopy (TEM), UV–vis spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FTIR). The concentration of residual silver and gold ions was measured by Inductively Coupled Plasma (ICP) spectroscopy. Silver and gold nanoparticle suspensions gave maximum UV–vis absorbance at 446 and 560 nm, respectively. The XRD data illustrated characteristic diffraction patterns of the elemental silver and gold phases and the average size of the crystallites were estimated from the peak profiles by Scherrer method. FTIR spectra of the leaf extract before and after the development of nanoparticles were determined to allow identification of possible functional groups responsible for the conversion of metal ions to metal nanoparticles.

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