Antibacterial nanobombs

Nanowire kills bacteria

Vladimir Fradkin, Deutsche WelleNanoparticles usually have properties that differ from the properties of macroportions of the same substance.

Now it turned out that water is no exception in this regard.

Of course, money, prestige or vanity may well be the motive that guides this or that researcher in his work, but in most cases scientists are still driven by scientific curiosity, not to say banal curiosity.

In any case, it was curiosity that prompted the American physicist, Professor of Harvard University Philip Demokritou and his colleagues to turn to the study of fine water: "We know that any substance crushed to the size of nanoparticles acquires very unusual properties – both physical, chemical, and biological," says the scientist. – However, until now, all such experiments have been limited to solid materials. We decided to see how the water nanodrops behave."

Electrospray sprays waterHarvard researchers used an electrospray to obtain nanodrops of water suspended in the air.

Electrospray is a method of ionization of liquid substances by spraying in an electric field, widely used in modern mass spectrometry. The method makes it possible to obtain electrically charged droplets of the correct shape and almost the same size. Professor Democritus managed to spray water to drops with a diameter of 25 nanometers, which is a thousand times smaller than the diameter of a human hair.

Nevertheless, the resulting aerosol turned out to be surprisingly stable, says the scientist: "We found, for example, that the electric charge increases the surface tension of the droplet, and the process of its evaporation slows down. As a result, these artificially produced water nanostructures are able to float in the air for a long time, although usually water droplets of this size evaporate instantly, in a fraction of a second."

High stability of nanoaerosolIn the experiments of Harvard scientists, nanodrops of water obtained by electrospray were stored in the air in a suspended state for three to four hours.

Moreover, they contained not only H ₂ O molecules, explains Professor Democritus: "Electrospray leads to the splitting of water molecules, resulting in the formation of hydroxyl and superoxide radicals, that is, reactive oxygen species. These ions are, as it were, enclosed in water droplets with a diameter of 25 nanometers."

Diagram from the page of the Center for Nanotechnology and Nanotoxicology of the Harvard School of Health
(Harvard School of Public Health Center for Nanotechnology and Nanotoxicology) – VM.

The presence of oxygen radicals with exceptionally high reactivity gave the scientist reason to call the droplets he received nanobombs, since they turned out to be an extremely effective disinfectant. When nanodrops of water suspended in the air come into contact with bacteria, oxygen radicals destroy the membranes of bacterial cells, and the bacteria die.

Efficiency, safety and environmental friendliness of nanowiresThis opens up the prospect of a completely unexpected application of water nanodrops.

"They can be used, for example, to disinfect the air – and thus maintain the sterility of fresh agricultural products," the researcher points out. – Or, say, you can disinfect wounds with water. This simple and non-chemical disinfection method can become an extremely effective means of combating infectious diseases."

However, one important question arises here: is the nanowire safe for human health? After all, all other nanoparticles, if they get into the lungs with inhaled air, cause inflammatory reactions or tissue damage up to malignant neoplasms. Professor Democritus performed a number of toxicological studies on mice and, to his own surprise, did not find any alarming signs.

The scientist explains it this way: "Our lungs are covered from the inside with a thin layer of mucus. The epithelial cells of the lung tissue are located under this mucous layer. Nanodrops of water, once on this watery coating, are immediately neutralized and dissolved. That is, they do not come into contact with epithelial cells at all, and therefore cannot cause damage to lung tissue, as happens in the case of other nanoparticles."

We are not talking about practical application yetSo, it turns out that nanowire is an effective and safe bactericidal agent for humans, moreover, it does not leave behind decay products.

Sounds impressive. But we are not talking about the practical application of nanowire yet, says Professor Democritus: "We would like to collect more information about possible negative effects on health. Although the results of the first toxicological inhalation experiments on mice look promising, we must also study possible long-term effects."

If no problems arise at the same time, then it will be possible to talk about the practical use of the nanowire. Some of the scientist's ideas look like perfect fiction today: for example, a miniature device connected to the USB connector of a computer for spraying water in an electric field. Such a device will create an invisible protective shell around the workplace, a kind of screen that reflects the threat of bacterial infections with the help of nanobombs.

Portal "Eternal youth" http://vechnayamolodost.ru23.01.2014