Siberian Federal University

Iron nanoparticles are increasingly used in medicine and environmental management: scientists already know their ability to penetrate through the cell membrane thus purposefully destroying cancerous tumours. No less interesting is the use of such nanoparticles as reusable adsorbents for hazardous substances: heavy metals and organic dyes, the remains of which get into rivers and lakes with sewage.

“We studied the properties of nanoparticles made of iron oxide and wrapped in a carbon coat, and tested how they cope with the extraction of anionic and cationic organic dyes (rhodamine and eosin, which give shades of pink and red) from water. It is no secret that household and industrial filters cannot extract these substances fully – trace amounts of dyes remain and then get into drinking water and soil. It turned out that both types of dyes are well adsorbed by the surface of the nanoparticles, which is largely due to the carbon coating which, like a sponge, absorbs pollutants, while the magnetite core enables to quickly remove nanoparticles from water to speed up the purification process,” stated Alexey Sokolov, co-author of the study, assistant professor at the Department of Experimental Physics and Innovative Technologies, SibFU.

Simple sorbents used to eliminate impurities work for a long time, they adsorb pollutants, and then they are either removed by specialists or they perish on their own if they are made from biodegradable material. The alternative offered by the scientific team of Krasnoyarsk scientists is a reusable sorbent, which works much faster and is completely removed from water after their mission is completed.

“Carbon-wrapped iron oxide nanoparticles are easily collected using a magnetic field – they can be chemically cleaned of collected contaminants and reused. An analogy with activated carbon suggests itself – it can also be restored and reused,” continued the researcher.

The most obvious use of such reusable adsorbents are filters that enable to create recycling (circulation) of water with the concomitant disposal of toxic impurities — not only anionic and cationic dyes found in household chemicals and food products but also heavy metal ions such as copper and lead will be caught and neutralized.

By the way, specialists can analyse water using the magnetic sorption method even near open waters – they take a small sample and run it through a filter. According to the expert, this way, even the smallest impurities of toxicants, which can be missed by laboratory instruments that do not detect values below the maximum allowable concentration (MAC), can be detected.

The second area in which iron oxide nanoparticles with a carbon coat can be successfully used is medicine. Alexey Sokolov explained how nanoparticles work when they penetrate into a cancer cell.

“Nanoparticles have long been widely used to target drugs or kill cancer cells. There are experiments with gold-coated nanoparticles carried out, in particular, by SibFU chemists. The mechanism of operation of our nanoparticles is similar. Aptamer tags can be set on such particles and directed to the affected organ, where, under the influence of an alternating electromagnetic field, the particles will begin to vibrate, destroying cell membranes and destroying tumour cells from the inside. By the way, it turned out that carbon coating can completely replace expensive gold,” the expert said.

The Ehrlich carcinoma cell disruption experiment was sequentially carried out using a low frequency alternating magnetic field. The number of cells destroyed as a result of their interaction with iron oxide nanoparticles in an alternating magnetic field is 27% more relative to control cells.

The Ministry of Education and Science of the Russian Federation was the first to share the news.