Posted: May 16, 2007

Growing nanoparticles from the inside out

(Nanowerk News) Gold particles have been grown inside silica nanoshells in an inside out approach to synthesis.
Coating silica onto metal nanoparticles is a known method of stabilising and functionalising nanoparticles, but a technique developed by researchers in Germany and the UK takes the reverse approach, using hollow silica particles as nanoreactors to grow gold particles ("Au–silica nanoparticles by reverse synthesis of cores in hollow silica shells" – free access article).
Schematic illustration of the formation of gold-silica nanocomposites
The silica's cavity (yellow) was filled with a gold precursor (orange), which was reduced to form the gold core (pink) of the nanocomposite
The scientists, led by Sara Cavaliere-Jaricot at Albert-Ludwig University, Freiburg, Germany, and Thomas Nann at the University of East Anglia, Norwich, UK, added a gold precursor and a reducing compound to the silica's cavity to form silica coated gold nanocomposites. The size of the nanocomposites can be controlled by tailoring the cavity size of the silica reactors.
Nann believes these nanoparticles could be used as functional carriers for drugs or contrast agents, or as surface rich materials for gas sensing or storage.
'There are so many challenges in this field,' said Nann. For him, the biggest challenge is the complete understanding and ability to control the surface chemistry of nanoparticles. 'In my opinion, this is the key to almost any successful future application,' he said.
Source: Chemistry World (Elinor Richards)