A team of specialist from the laboratory of radiocarbon methods of analysis of Novosibirsk State University and a number of institutes of the Russian Academy of Sciences conducted a study using accelerator mass spectrometry, the results of which have shown convincingly that artificial nanoparticles, which increase in number in the surrounding atmosphere, are really hard to remove from mammalian organisms. Inhaled particles accumulate in the lungs, then spread throughout the body, getting into kidneys, liver, brain, and after a quarter of the quarter of life of mice (about six months) they are still recorded in the lungs.
The staff of Laboratory of radiocarbon analysis methods (LRMA) of Novosibirsk State University and a number of institutes of the Russian Academy of Sciences conducted a study using the technique of accelerator mass spectroscopy (AMS) in mice and found that the solid aerosol particle size of 200 nanometers at a very low concentration (1000 pieces per cubic centimeter), penetrating into the body through the lungs, accumulate in kidneys, liver and brain, and thus dont accumulate in the heart. The particles size of 80 nm at a concentration of 10,000 units per cubic centimeter of air inhaled remains in the lungs for at least six months after exposure.
Previously, experts using accelerator mass spectrometry, based on counting the number of carbon14C isotopes in the samples, the staff of LRMA NSU developed detection method in the body of the bacterium Helicobacter pylori, and dated the remains found on the site of the transit prison of the NKVD in Novosibirsk.
The used low concentration of aerosols is as close as possible to the natural conditions of urban air, that is, roughly the amount of particulate matter contained in the ambient air of people (0.8-2 micrograms per cubic meter or 10,000-50,000 units per cubic centimeter).
The first results of the study were published in the article Ultrasensitive detection of inhaled organic aerosol particles by accelerator mass spectrometry in the September issue of the journal Chemosphere (IF = 3,7). According to the portal ResearchGate, the article of the researchers has become a leader in the number of readings of all the papers published in the field of accelerator physics.
The work involved experts from the laboratory of radiocarbon analysis methods (LRMA) of NSU, Institute of Catalysis SB RAS, Novosibirsk Institute of Organic Chemistry, Institute of Chemical Kinetics and Combustion SB RAS, Institute of Nuclear Physics SB RAS, Scientific Center of Clinical and Experimental Medicine, and Tion Company.
According to the author, senior scientist of the Laboratory of radiocarbon analysis of NSU and Institute of Catalysis SB RAS, Yekaterina Parkhomchuk, a group of scientists not only obtained new data on the accumulation of nanoparticles in bodies, but also offered a simple way to track the movement of aerosols in the body in extremely low concentrations.
Using the method AMC enabled to increase detection of sensitivity in the body and substances in the natural, that is, inhalation, way:
- In order to learn, how the particles of soot or medicine are spread, you need isotope 14C to enter into a particle and the problem with the registration is solved. The body 14C content is negligible - about 10-12, and AMS may see single particle of the rare isotope among 1,015 particles primary carbon isotopes - 12C. This radioactivity in substances even locks counters decay and doesnt require special operating conditions, - Yekaterina Parkhomchuk says.
The experiment consisted of several stages involving a large team of different specialists. Synthetic chemists obtained styrene-labeled 14C, including polystyrene micro- and nanospheres. Physics of aerosol-thought out as the spray solution prepared so that the air didnt let agglomerates and individual particles. Biologists working with mice, chemists, professionals, who carried out the isotopic analysis of carbon, prepared graphite targets from biological tissues.
Results showed that after five days of exposure to the aerosol, particles of size of 200 nm during 30 minutes a day in the lungs of mice accumulated several million particles or about 90 nanograms per 1 g of mouse weight. The particles were also detected in kidney, brain and liver, but werent registered in the heart. A similar effect of particle size of 80 nm showed that the nanospheres of this size are retained in the lungs of mice for at least six months.
Yekaterina Parkhomchuk noted previously that the 200 nm size particles dont penetrate beyond the lungs into the body and excreted through the upper respiratory tract, however, research refuted this assertion. Furthermore, foreign particles, for example, the ones contained in the combustion products that accumulate in the body, can lead to negative consequences for the internal organs, including cancer.
Developments of AMS and LRMA of NSU together with the institutes of the SB RAS will be used when creating the methods of targeted delivery of medicine, for example, a sustained release formulation of medicine for the treatment of tuberculosis (in collaboration with the Scientific Centre of Clinical and Experimental Medicine), and new chemical products for boron neutron capture therapy of cancer.
Meanwhile, members of the Physics Department of Lomonosov Moscow State University developed a method of synthesis of silicon nanowires using metal-stimulated etching, where instead of hydrofluoric acid (HF) a safer and more environmentally friendly ammonium fluoride (NH4F) was used. Results of the research were published by scientists in Nanoscale Research Letters journal.
A two-step etching method was used. At the first stage silver nanoparticles were deposited on the surface of the silicon substrate. But they werent deposited as a uniform layer, and islands. At the second stage, the silicon substrate was etched in areas covered by silver. Therefore, unsecured silver portions of the silicon wafer turned into nanowires. Silver nanoparticles were sinking into the silicon wafer, and lasted longer than the etching ones, the longer nanowires were obtained. In the end, the silver was removed with nitric acid, - the junior researcher of the Department of low temperature physics and superconductivity of the Physics Department of Moscow State University, Kirill Gonchar, explains the general scheme of creating nanowires.