AKSON Russian Association of Science Communication

Image: This is a schematic diagram of the interaction mechanism between radiation and nanoparticles. A-semiconductor state B-plasma state. see more 

Tungsten oxide has attracted great attention from scientists and industrialists because of its wide application in photochromic and electrochromic devices, photosensitive materials, and biomedicine. For example, it can be used as an X-ray contrast agent for computed tomography-a basic diagnostic tool for visualization of internal organs. In addition, based on high photocatalytic activity, tungsten oxide has a strong antibacterial effect, which can be further enhanced by ultraviolet radiation and the use of smaller tungsten particles. Therefore, tungsten oxide is currently used as a visible spectrum photocatalyst for wastewater purification.

Chemists from the Russian Institute of Theoretical and Experimental Biophysics (ITEB RAS), the Institute of General and Inorganic Chemistry, and colleagues from the Ukrainian Institute of Microbiology and Virology obtained a nano-dispersed tungsten oxide colloidal solution. The scientists conducted a complex analysis of the particle characteristics and proved their photocatalytic activity through the photodegradation of the indigo carmine pigment. In the presence of tungsten oxide particles, even in sunlight, the pigment will quickly decompose. If additional ultraviolet radiation is applied, even if the particle concentration is very low, the process will be significantly accelerated.

The team studied how the new particles affect various biological objects, including Gram-positive and negative bacteria, Candida and mouse cells. Anton Popov, a member of the ITEB RAS Cell and Tissue Growth Laboratory, commented on the study: "We analyzed the cytotoxicity of tungsten oxide particles to prokaryotic microorganisms and eukaryotic cells. They show different sensitivity to particle effects, which is obviously different from that. Cell morphological characteristics are related. Membrane and metabolic differences."

During the experiment, the researchers treated the cells with a series of particle concentrations, irradiated the cells with ultraviolet light and assessed their condition. They specifically checked the level of reactive oxygen species and the speed of cell division. The results show that the toxic effect of tungsten oxide depends on the particle dose and UV exposure time. Interestingly, low-concentration tungsten oxide is harmless to mouse cells, but it is fatal to bacteria. Presumably, this is related to the difference in membrane structure between prokaryotic and eukaryotic cells. However, regardless of the cell type, high concentrations of tungsten oxide exhibit significant toxicity.

Another notable feature of the new particles is their selective toxicity to cancer cells, which opens the way for new promising research fields. Because the particles are selectively toxic to cancer and can be used as X-ray contrast agents for computed tomography, they can be used for therapeutic diagnosis. This is a new method of designing drugs that can be used as both diagnostic and therapeutic agents.

Experimental data shows that this new particle has more applications. For example, coatings based on such particles can be used to provide biosafety in public places, such as hospitals, supermarkets, or public transportation. Nevertheless, studies have also shown that tungsten oxide should be used under strict control to avoid toxic effects on the human body. The research on the synthesis and properties of tungsten oxide nanoparticles was carried out with funding from the Russian Science Foundation.

Journal of photochemistry and photobiology

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AKSON Russian Association of Science Communication

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Copyright © 2021 American Association for the Advancement of Science (AAAS)