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Nanoparticles can be cast in glass

Porous silicon dioxide can be used as molds for Nanoparticles. The pores can also be adapted so that the particles are the exact the size required, explains Mohamed Ballem in his doctoral dissertation.

Mohamed Ballem

Porous silicon retains many uses such as in filters for the purification of drinking water, for biosensors or catalytic converters. However the material can also be used as a mold to produce quantities of identically sized nanoparticles of metals or metal oxides.

Imagine a bath sponge, where the exact size of the holes can be controlled. The sponge absorbs the required substance to produce nanoparticles of, and then expose the entire amount to heat that constitutes a reaction in the pores. Once all the cavities are filled the sponge is dissolved. The remaining nanoparticles can be collected by means such as centrifugation.


It sounds simple and ingenious and Mohamed Ballem shows that it works in his doctoral thesis.

There are of course other methods that can produce nanoparticles, each with advantages and disadvantages. However the distinct to this method, with porous silicon dioxide as a mold, is that the mold cavities can be formed (pores) so that the particles are identical in size.

Another advantage is that the silicon dioxide can serve as packaging for transport or storage. The particles are bound in silicon dioxide and can be released exactly when they are needed.

"It's easy once you know how to do", declares Mohamed Ballem.

Handling nanoparticles is undoubtedly important, especially in light of the research conducted on health effects. The particles are as small as the body's enzymes and proteins, and yet it is unknown if and when they cause damage to the human body.

Actually, nanoparticles have many uses. They can be used in a variety of contexts such as; sunscreens, cosmetics, coatings, reinforcing steel, as transporters of medicines, catalytic converters and much more.

"Mohamed’s work illustrates that this is a wide-ranging method that works for many different materials. He also identifies that fungal properties can be altered and thus alter the size of the particles, which in turn, alters their character."

"And he has got this to work, "says Magnus Odén, professor of materials science at Linköping University.

Magnus Odén came to LiU in 2007 from Luleå University of Technology and since that time he has developed research on nanomaterials. Mohamed Ballem is the first from the research group to defend a thesis.

Following his doctorate, he will continue his research by studying nanoparticles of cobalt, made of silicon dioxide. Cobalt is magnetic and theses magnetic properties dependent on particle size. The question is whether materials can be custom-made using particles with a certain type of magnetic property.

"It should be possible, " said Mohamed Ballem.


The thesis is entitled Synthesis of Mesoporous Silica and their Use as Templates for Metal and Metal Oxide Nanoparticles, Department of Physics, Chemistry and Biology, Linköping University.
Mohamed Ballem will defend his dissertation, May 31

Monica Westman Svenselius Fri May 27 13:39:00 CEST 2011

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