Boron combined with silver…
...against cancer and bacteria
NUST MISIS scientists together with colleagues from the State Research Center for Applied Microbiology and Biotechnology and the University of Queensland (Brisbane, Australia) have developed hybrid nanomaterials based on boron and silver nitride, showing their effectiveness in cancer therapy, as well as as new catalysts and antibacterial agents. The results of the study are published in the Beilstein Journal of Nanotechnology (Firestein et al., BN/Ag hybrid nanomaterials with petal-like surfaces as catalysts and antibacterial agents).
The stage of studying individual nanoparticles (fullerenes, nanotubes) has been replaced by the stage of studying combinations of various materials at the nanoscale. When the material is reduced to nanoscale sizes, new physicochemical properties of the substance suddenly appear, its electronic structure changes. For example, a magnet with a reduction in size to one hundred nanometers may cease to be a magnet.
In addition, scientists have noticed that often combinations of different nanomaterials exhibit improved or even new properties compared to individual particles. In addition, a set of properties is required for a number of applications, and nanoparticles do not have such a complex.
"Scientists of the Inorganic Nanomaterials Laboratory of NUST MISIS, led by Professor Dmitry Shtansky, PhD, as part of an international research team, took part in a study on the properties of hybrid nanomaterials by combining boron nitride and silver nanoparticles. The obtained substances can be primarily used in oncology as a basis for targeted drug delivery to the tumor," said Alevtina Chernikova, Rector of NUST MISIS.
Boron nitride was chosen as the base because it has a low density, while being chemically inert and biocompatible.
"We have studied the properties of nanohybrids, demonstrating their potential in a number of situations. We were particularly interested in catalytic and antibacterial activity," says Andrey Matveev, one of the authors of the study, senior researcher at the Laboratory of Inorganic Nanomaterials at NUST MISIS.
For use in antitumor therapy, nanohybrids are chemically modified by "sewing" to the surface of folic acid (vitamin B9) through a silver nanoparticle. Thus, nanohybrids turn into "containers" – they are impregnated with medicine and injected into the body.
Thanks to folic acid, nanohybrids accumulate mainly in cancer cells, where their concentration is a thousand times greater than in healthy ones. The acidity inside the tumor cell is higher than in the intercellular space. The change in acidity, respectively, leads to the release of the drug from the nanocontainer.
"Thus, the drug is secreted almost exclusively inside cancer cells, which greatly reduces the total concentration of the drug in the body – and, as a result, prevents intoxication," Matveev notes.
According to the authors, nanohybrids modified for targeted delivery are also relevant for isotope and boron-neutron capture therapy of oncological diseases. They can also be used as photoactive materials in the ultraviolet range.
In addition, the synthesized nanohybrides showed high catalytic activity during methanol oxidation. This circumstance is significant, in particular, for green energy. One of its key tasks is to search for effective methods of producing hydrogen, a convenient and renewable source of which is now considered methanol. Highly active and stable catalysts are important to increase the efficiency of this process. NUST MISIS scientists have found out that boron nitride nanoparticles not only act as carriers of catalytically active silver nanoparticles, but also significantly increase their activity.
Also, the synthesized nanohybrids showed high antibacterial activity against the test bacteria Escherichia coli – E. coli, which is usually found in dirty water. Therefore, disinfection of water with these hybrid particles may be relevant in wartime or in emergency situations.
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