Research and assessment of the molybdenum oxide (VI) nanoparticles toxiсity under inhalation in WISTAR line rats in comparison with the micro-sized chemical analog
Authors: Zemlyanova Marina A. , Zaitseva Nina V. , Stepankov Mark S. 
Published: November 2023

Introduction. Molybdenum (VI) oxide nanoparticles (MoO3 NPs) are being actively introduced into practical use as part of catalysts, optics, plastics, textiles, coatings, and lubricants, gas sensors, and crude oil refining processes. MoO3 NPs are known to exhibit toxic properties when interacting with living systems. Atmospheric air pollution with potentially dangerous MoO3 NPs can contribute to the inhalation exposure in the population and, as a result, the development of health disorders caused by the toxic effect of the nanomaterial. In this regard, the study of the adverse effects caused by MoO3 NPs entering the body during aerogenic exposure is particularly relevant.

The aim of the study. Investigation and evaluation of subacute toxicity of MoO3 NPs by the inhalation route of entry into the body in comparison with a microsized chemical analogue.

Materials and methods. The physical properties of MoO3 NPs were studied in comparison with microparticles (MPs). In an experiment on Wistar rats, a comparative analysis was performed and a characteristic of the pathogenetic features of the toxic effect of particles during subacute inhalation exposure at a concentration of 1.84 mg/m3 was given.

Results. According to the totality of physical properties, the MoO3 sample under study is a nanomaterial with an average particle size of 58.8 nm, constituting 84.2% of the total number of particles. MoO3 NPs accumulate in the heart, lungs, kidneys, and brain. The concentration of molybdenum is by 2.50–15.85 times higher than the control levels. The highest content of the studied element was found in the lungs. Bioaccumulation of MP MoO3 was noted only in the lungs, while the concentration of molybdenum is by 3.00 times less in comparison with the exposure to NPs. When exposed to MoO3 NPs, more pronounced changes in biochemical (an increase in the activity of alkaline phosphatase, LDH, the concentration of total bilirubin and creatinine by 1.29–2.11 times) and hematological parameters (a decrease in the number of platelets and thrombocrit by 1.2 times) of blood were noted relative to the impact of a microscale analogue. Under the influence of NPs and MPs of MoO3, pathomorphological changes develop in the lungs, brain, and liver tissues. When exposed to NPs, compensatory lung emphysema, focal microvesicular steatosis in hepatocytes, and acute plethora in the liver were found, which were not detected during exposure to NPs.

Limitations. The study was performed only with subacute inhalation exposure to NPs and MPs of MoO3 in Wistar rats.

Conclusion. MoO3 NPs have a higher degree of bioaccumulation and toxicity relative to MPs. The results of the study make it possible to expand theoretical concepts and gain new knowledge in the field of nanotoxicology about the features of the toxic effect of nano-sized MoO3 with multiple inhalation routes of entry into the body at a concentration of 1.84 mg/m3.

Compliance with ethical standards. The study was carried out in accordance with the European Convention for the Protection of Vertebrate Animals used for Experimental or other Scientific Purposes (ETS No. 123) and the requirements of the Ethics Committee of the Federal Scientific Center for Medical and Preventive Technologies for Public Health Risk Management (protocol No. 6 of 20.01 .2021).