Scientists Develop Advanced Composite Synthesis Technology

14:57, November 5, 2020

The work of the Ural scientists is truly innovative

Scientists from Ural Federal University and the Institute of Electrophysics of the Ural Branch of the Russian Academy of Sciences, using an original technique, synthesized composites with pronounced antibacterial properties based on silver nanopowders and aluminum oxide powders. The co-authors published an article describing the content and results of the experiments in the journal Radiation Physics and Chemistry.

In the finished form, the research product will look like this: mesoporous nanoscale alumina will serve as a "vehicle" for various drugs, for example, antibiotics, and the silver coating will give the composite additional antimicrobial properties, because if microbes become immune to antibiotics over time, then they will be resistant to they do not possess silver.

The work of the Ural scientists is truly innovative.

“The first difference in our technology is that we use pulsed electron beams to produce silver-coated aluminum oxide powders. Therefore, the energy is released in a very short period of time, within the order of 50 nanoseconds, and the reactions proceed differently than when using constant electron beams. As a result, the composite nanopowders we have obtained have a fractal structure, consist of many pores, and the amount of drugs “loaded” into them is no less than that of the best foreign analogues, ”explains the head of the research group, professor of the Department of Experimental Physics of UrFU, leading researcher of the Institute of Electrphysics at Ural Branch of RAS Sergei Sokovnin.

Secondly, scientists have created a new method for producing silver nanopowders: using polyhydric alcohols - glycerin, xylitol, sorbitol (their choice was dictated, among other things, by safety for humans) - a solution of silver nitrate was prepared, under the influence of a pulsed electron beam, it disintegrated, forming atoms silver, which condensed on OH-groups of polyhydric alcohols. Experiments, in particular, have shown that irradiation in a xylitol solution leads to a 15-fold increase in the specific area of ​​the powders obtained (the maximum specific surface area of ​​silver nanopowders obtained by Yekaterinburg residents is 39.1 cm2 / g).

“We have discovered for the first time that the number of OH groups in polyhydric alcohols is a significant factor: they are the centers of formation of silver nanoparticles, and the more such centers, the less silver nanoparticles that condense on them. Our group managed to obtain silver particles 5–15 nanometers in size, ”continues Sergei Yurievich.

Third, at UrFU and Russian Academy of Science, they achieved that the size of the surface of a composite nanopowder coated with silver can be controlled by the exposure time after irradiation (for this, a suspension based on a sorbitol solution was used). It was found that the coverage area of ​​the oxide base can vary from 2–3% to 16–40%: in the first case, the holding period of the composite was 15 hours, and the size of the silver particles reached 50 nanometers, in the second, the composite was kept for 96 hours, the silver particles grew to 80 nanometers.

The larger the area covered with silver, the correspondingly stronger the antibacterial properties of the composite. And since only the surface layer of silver possesses such properties, it can be replaced “inside” the composite with the same oxide of cheaper aluminum, thus making the technology cheaper and significantly reducing the consumption of the precious metal.

The antibacterial properties of the composite were studied on wine yeast, Escherichia coli and Staphylococcus aureus. In all cases, the material proved to be effective.

We add that the research was carried out with the financial support of the Russian Foundation for Basic Research and the Sverdlovsk Region within the framework of the scientific project No. 20-48-660019 r_a “Development of radiation technology for the production and study of the physicochemical properties and biological activity of silver-coated metal oxide nanopowders for the creation of drugs and drug delivery systems ”.

“The next challenge for us is to find a stabilizing agent to obtain a more uniform silver coating of the oxide base and, using fillers such as silicon and bismuth, to develop a multifunctional drug that will simultaneously be a drug carrier and an antibacterial agent that is easy to detect. using x-rays. This will allow for targeted therapy, delivering drugs to a given area of ​​the body, ”concludes Sergei Sokovnin.

The planned scientific program will be carried out with the involvement of specialists from the Institute of Natural Sciences and Mathematics of the Ural Federal University, the Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, and the Ural State Medical University.

The development of new methods for obtaining silver nanopowders and composites based on them is an urgent area of ​​natural science research in order to create new materials for the treatment of various diseases and pathologies and the development of biotechnologies. Thus, it is known that the use of silver-based composites is promising in the treatment of angiogenic diseases, such as cancer, and in bone tissue regeneration. In addition, the data shows composites are promising materials in arthroplasty, dental transplantation, and as photocatalytic agents for water disinfection.