Biogenic ferrihydrite nanoparticles were synthesized as a result of the cultivation of Klebsiella oxytoca microorganisms. The distribution of nanoparticles in the body of laboratory animals and the physical properties of the nanoparticles were studied. The synthesized ferrihydrite nanoparticles are superparamagnetic at room temperature, and the characteristic blocking temperature is 23–25 K. The uncompensated moment of ferrihydrite particles was determined to be approximately 200 Bohr magnetons. In vitro testing of different concentrations of ferrihydrite nanoparticles for the functional activity of neutrophilic granulocytes by the chemiluminescence method showed an increase in the release of primary oxygen radicals by blood phagocytes when exposed to a minimum concentration and a decrease in secondary radicals when exposed to a maximum concentration. In vivo testing of ferrihydrite nanoparticles on Wister rats showed that a suspension of ferrihydrite nanoparticles has chronic toxicity, since it causes morphological changes in organs, mainly in the spleen, which are characterized by the accumulation of hemosiderin nanoparticles (stained blue according to Perls). Ferrihydrite can also directly or indirectly stimulate the proliferation and intracellular regeneration of hepatocytes. The partial detection of Perls-positive cells in the liver and kidneys can be explained by the rapid elimination from organs and the high dispersion of the nanomaterial. Thus, it is necessary to carry out studies of these processes at the systemic level, since the introduction of nanoparticles into the body is characterized by adaptive-proliferative processes, accompanied by the development of cell dystrophy and tension of the phagocytic system.

The unique physical, chemical and magnetic properties of iron oxide nanoparticles (INPs) open up wide prospects for the use of nanomaterials in the diagnosis and therapy of various diseases. Despite the high interest from the scientific community, the mechanism of the effect of INPs on the physiology of living organisms has not been fully investigated. This is not least due to the fact that the toxicity of nanoparticles depends on multiple factors, including their size, method of synthesis, and the presence of a shell. This work was aimed to study the effect of synthetic and biogenic ferrihydrite INPs on the mouse kidney morphology, depending on the method of their synthesis and the presence of a polysaccharide shell after oral administration. The animals (n = 55) were allocated into 3 groups: group 1 (n = 15)—control mice, fed food without INP supplementation; group 2 (n = 20)—experimental mice, fed food supplemented with synthetic uncoated INPs; group 3 (n = 20)—experimental mice, fed food supplemented with encapsulated biogenic INPs. The biological material (mouse kidney) was sampled for standard histological examination a day before the onset of feeding with INP supplementation, as well as on days 22 and 36 after that. It was found that long-term administration of both synthetic and biogenic INPs was accompanied by hemodynamic disorders in the kidney, as well as dystrophic and necrotic alterations in renal parenchymal cells, leading to the development of renal failure. Biogenic INPs displayed a highest reactivity, which is probably due to the presence of a polysaccharide shell and the crystalline structure of the ferrihydrite core.

According to the World Health Organization, the most common (up to 90% of cases) hematological pathology is anemia, a condition characterized by a decrease in the level of hemoglobin in the blood due to a decrease in the total number of red blood cells or a violation of hemoglobin synthesis, which can have serious consequences for the body, such as decreased immunity, impaired respiratory and metabolic processes. Currently, it is necessary to improve the methods of prevention and treatment of anemia. To test new drugs for these purposes, it is necessary to create new models, including on laboratory animals. The aim of the study was to develop experimental models of iron deficiency (IDA) and hemolytic anemia (HA) on laboratory animals. The objects of the study were sexually mature male laboratory rats of the Wistar breed, aged 7 months and weighing 260 ± 20 g. 38 animals were involved in the experiment (for IDA n= 24, for HA n= 14). Laboratory animals were kept in the same external conditions for 3-4 individuals in a cage. To simulate IDA, rats were subcutaneously injected with the drug “Desferal”. To simulate GA, rats were intraperitoneally injected with the drug “Hydrochloric acid phenylhydrozine”. At each stage, blood was taken by cutting off the tip of the tail. A detailed blood test was performed on a hematological analyzer “Heska Element HT5”. As a result, it was found that when the drug “Desferal” was administered at concentrations of 125 and 250 mg / 100g per animal weight, hematological changes were observed in rats, such as an increase in red blood cells, platelets, leukocytes by stage 2 and a decrease to control values by stage 4. When the drug “Hydrochloric acid phenylhydrozine” was administered, hematological changes were detected in rats only within the experimental group. There was an increase in the indicators of erythrocytes, platelets, leukocytes by stages 2 and 3 and a decrease to control values by stage 4. Thus, when the studied drugs were administered in the presented dosages in vivo, a change in the hematological parameters of the blood was detected in the direction of an increase in their number due to adaptation to the effects of substances.

Iron oxide nanoparticles attract attention in the scientific community due to the wide range of their unique physico-chemical properties obtained during various synthesis methods. However, their effects on the body when administered orally have not been sufficiently studied. This work was aimed to study of morphological and morphometric characteristics of the gastric mucosa of laboratory mice using synthetic and biogenic iron oxide nanoparticles as a feed additive. Materials and methods. Nanoparticles of synthetic and biogenic iron origin were used in the work. The laboratory mice (n = 55) were allocated into 3 groups: 1 group of mice (n = 15) were intact animals that received standard feeding; group 2 (n = 20) fed food with synthetic nanoparticles; group 3 (n = 20) fed food with biogenic nanoparticles. The biological material (mouse stomach) was sampled on days 1, 22, and 36. Histological sections were stained with hematoxylin-eosin and Perls. Morphometric analysis of the drugs was performed in the program “ViodeoTesT - Morphology 7.0”. Results. Upon oral administration of iron oxide nanoparticles into the body, lymphohistiocytic infiltration, hemorrhages, enlargement of the gastric glands, cysts, and dystrophic changes in the cells of the columnar epithelium were detected in both groups. At the same time, foci of atrophic gastritis and pronounced foci of destruction of the gastric glands were noted in animals of group 3 on day 36. Conclusion. The entry of both synthetic and biogenic iron oxide nanoparticles into the gastrointestinal tract for 36 days causes pathological changes in the stomach tissue in the form of epithelial metaplasia with dystrophic changes in the gastric glands.