Scientists are developing a new method for producing irradiated nanomaterials for medical purposes

According to Petr Cígler, from the Institute of Organic Chemistry and Biochemistry (IOCB Prague) and Martin Hrubý of the Chemical Chemistry University of Chemical Chemistry (IMC), both of which are part of the Czech Academy of Sciences, a team of researchers has devised a revolutionary method for the easy and inexpensive irradiation of nanoparticles and the production of other nanomaterials suitable for highly sensitive diagnosis of diseases, including various types of cancers. Their article was recently published in a scientific journal Natural communication.

Sensitive and selective diagnostic tools are needed to diagnose diseases and to understand molecular processes in the cells. Nowadays, scientists can control the magnetic and electrical fields in cells with a resolution of several tens of nanometers and with considerable sensitivity due to crystal defects of some inorganic materials. For this purpose, the almost ideal material is a diamond. Compared to diamonds used in jewelry, those designed for diagnostics and nanomedicine – nanodiaments – are about a million times smaller and are produced synthetically from high pressure graphite and temperature.

However, pure nanodiamonds do not reflect the environment. First of all, its crystal lattice needs to be cleaned under controlled conditions in order to create special defects, so-called nitrogen vacancy centers that provide an optical image. The damage occurs most often when irradiated nanoparticles with fast ions in particle accelerators. These accelerated ions are able to capture carbon atoms from the outside of the nanodiamond crystal lattice, leaving behind holes known as vacancies, which then connect at high temperatures with nitrogen atoms in crystals as pollutants. Newly created nitrogen vacancy centers are fluorescence sources that can be observed. It is precisely this fluorescence that gives nanodiamants a huge potential for applications in medicine and technology.

However, the fundamental limitation of the use of these materials on a wider scale is the high costs and poor efficiency of the ionizing radiation, which prevents the production of this extraordinarily valuable material in larger quantities.

A research team from several research centers led by Petr Cígler and Martin Hrubý recently published an article in the journal Natural communication describing a completely new irradiation of nanocrystals. By paying expensive and time-consuming radiation in the accelerator, scientists used the radiation in a nuclear reactor, which is much faster and much cheaper.

But that was not that simple. Scientists had to use the trick – the neutron irradiation in the reactor divided the boron atoms into very light and fast helium and lithium ions. First, the nanocrystals should be melted in molten boron oxide, and then the neutron irradiation should be activated in the nuclear reactor. The capture of neutrons with boron nuclei results in dense helium and lithium-ion showers whose nanocrystalline effects are the same as those produced in a gasolator: controlled crystal defect generation. This high density particle shower and the use of the reactor to radiate much more materials means that it is easier and more advantageous to simultaneously produce dozens of rare grams of nanoparticles, which is about a thousand times more than scientists have been able to get by now with comparable radiation accelerators.

The method has proved to be successful not only in creating defects in a nanodiamide grid but also in another nanomaterial as well as in silicon carbide. For this reason, scientists assume that this method could be found for universal applications in the production of large-scale nanoparticles with certain defects.

The new method uses the principle of boron neutron capture therapy (BNCT) in which patients are given a boron compound. When the compound is collected in the tumor, the patient receives radiation therapy with neutrons, which split the boron nuclei into helium and lithium ion. They then destroy the tumor cells that boron has collected. This principle, taken from the experimental treatment of cancer, has thus opened up opportunities for the efficient production of nanomaterials, which has the extraordinary potential to apply, among other things, the diagnosis of cancer.