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Scientists of St. Petersburg State University have established patterns of changing the shape and size of nanoparticles used in theranostics (an innovative field of medicine) by adding various lanthanides to the structure. The use of particles of a certain shape and size is important when conducting anti-cancer therapy or MRI diagnostics, where it is necessary to use the smallest particles, since they penetrate cells more easily and are able to move freely through blood vessels and veins without clogging small capillaries.

Theranostics is a young and actively developing field of medicine that explores the possibilities of creating and using drugs that allow simultaneous diagnosis of diseases and their therapy with the help of special combined materials-drugs. The creation of such materials has become possible only in recent years — largely as a result of the development of nanotechnology. These drugs make it possible to find a problem area in the patient's body that requires treatment, deliver the necessary medicine there and immediately visualize the affected area for the doctor in real time (either by optical spectroscopy or using a widely used magnetic resonance imaging method). According to scientists, combined drugs do not have a negative effect on the patient's body and cause less discomfort during treatment.

The practical component is important for the development of such drugs, but there are also important fundamental problems. For example, the question of the connection of the beneficial properties of drugs with the sizes of micro- and nanoparticles in the form of which drugs are manufactured is fundamental.

Scientists at St. Petersburg University have studied nanoparticles based on sodium and yttrium fluorides and rare earth elements - chemically inert and insoluble substances that do not harm the body. In addition, these elements, as a rule, have a brighter luminescence (glow) and in the future can be used as dyes for fluorescent microscopy, as well as for medical purposes (for example, during non-invasive diagnostics of tumors).

During the work, a team of researchers led by Andrey Mereshchenko, Doctor of Chemical Sciences, Associate Professor of the Department of Laser Chemistry and Laser Materials Science of St. Petersburg State University, synthesized several dozen compounds, in each case varying the composition of the resulting material by adding various salts of rare earth elements. This was necessary to accumulate experimental material for further analysis.

"The purpose of this large study was to search for patterns of the influence of the nature of rare earth elements in the composition of preparations on the size of the resulting nanoparticles. To do this, it took a lot of similar studies with controlled changes in the composition of particles. The periodic law gives us the opportunity to predict the properties of yet unknown compounds based on known data about their analogues. We used this approach as the main theoretical tool," commented Andrey Mereshchenko.

Scientists applied the classical approach of the scientific school of chemists of St. Petersburg State University, which allows to find and explain fundamental laws in the properties of substances using the Periodic Law, discovered in 1869 by the famous universalist Dmitry Mendeleev.

As a result of the work, scientists managed to obtain particles ranging in size from 80 to 1100 nanometers (one nanometer is one billionth of a meter). It is important to note that the size and shape of the particles directly depend on the nature of the rare earth element ion. This dependence is nonmonotonic in nature: particles decrease when moving from left to right along a series of lanthanides in the Periodic System from lanthanum to gadolinium (57-64 th elements of the Periodic System) and increase in the second part of this series - from gadolinium to lutetium (64-71 th elements of the Periodic System). All particles have the shape of hexagonal prisms, for which the ratio of diameter to height also depends on the nature of the rare earth ion, which ensures a change in the geometric parameters of the particles when using various components of the preparation.

Earlier, chemists of St. Petersburg State University synthesized new luminescent nanoparticles for use in laser microscopy, as well as for the diagnosis of various diseases using contrast. These nanoparticles were also created on the basis of rare earth metals — yttrium and europium — with the addition of gadolinium ions.

"It was interesting to find that it is in the case of gadolinium that the particle size is minimal. After all, drugs based on it are the most promising for use in MRI diagnostics due to their magnetic properties, similar drugs can already be found. And reducing the particle size makes it possible to increase their penetrating ability into cells with any pore size and, accordingly, apply them to any living tissues," explained Nikita Bogachev, the first author of the scientific article, senior lecturer at the Department of General and Organic Chemistry of St. Petersburg State University.

Currently, the team continues to work and is now focused on optimizing the directed synthesis of particles with multifunctional properties: capable of emitting light under the influence of ultraviolet, electromagnetic field or other disturbances (luminescence) and at the same time applicable as a composition of MRI contrasts.

For information

The research was carried out on the equipment of the resource centers of the St. Petersburg State University Science Park, which allowed the analysis of particles using instrumental methods. Young employees of the research team — students of the 1-2 courses of St. Petersburg University took part in the synthesis of particles. The work was carried out within the framework of a grant from the President of the Russian Federation for state support of young Russian scientists — doctors of sciences.

The article was published in the journal Nanomaterials, a graphic image of the work of St. Petersburg State University scientists appeared on the cover of the publication.

Image: Graphic abstract to the article by St. Petersburg State University scientists: the effect of rare earth ions depicted as presses on initially identical NaYF4 particles allows us to obtain other particles with a new shape and size from them
Source: St. Petersburg State University Press Service, sci-dig.ru