MOSCOW, November 8. /TASS/ Scientists from the Lebedev Institute of Physics of the Russian Academy of Sciences (LPI RAS), the Skolkovo Institute of Science and Technology (Skoltech), and the Moscow Institute of Physics and Technology (MIPT) have shown that at normal conditions silica nanoparticles exist in quite an unusual form which is enriched with oxygen and possesses magnetic properties and enhanced chemical reactivity. This might be the reason for high toxicity and carcinogenicity of silica nanoparticles, Skoltech’s press service reported.

"We were quite surprised that it was not ordinary SiO2 nanoparticles that appeared to be stable at normal conditions in an oxygen atmosphere but other chemically active, magnetic nanoparticles were discovered instead," says Sergey Lepeshkin, the leading author of the research.

Silicon nanoparticles are promising for many applications including solar cells, biosensors, and other nanoelectronics devices, that’s why they have been in the spotlight of intense research for over two decades. However, in an oxygen atmosphere, silicon nanoparticles oxidize yielding the silica (aka silicon oxide) which shows a pronounced negative effect on human health and causes silicosis and lung cancer, but the nature of this effect has been unknown up to now.

In their study, scientists from the research teams of Professor Artem Oganov from MIPT and Skoltech and of Yuri Uspensky from LPI RAS have shown by means of the USPEX algorithm (Universal Structure Predictor: Evolutionary Xtallography) that at normal atmospheric conditions silica nanoparticles exist not with the expected classical composition SiO2 postulated by classical chemistry, but in an oxygen-enriched form (e.g., Si7O19).

Attached excessive oxygen atoms demonstrate magnetic properties and form reactive oxygen species such as peroxide, ozonide ions, and oxo radicals which react with essential biomolecules in the body leading finally to the development of cancer. The scientific paper summarizing the finding has been published in the Nanoscale.