In this work γ-Fe2O3 MNPs were obtained by laser target evaporation and water based suspensions were prepared. Maximum permissive dose of iron in water (MPD) is 0.3 mg/L. It was found that 100 MPD dose of iron induces formation of non-typical colonies after 72 or 96 hours exposition: against a background of small black colonies large white colonies appeared due to a disruption in tyrosine synthesis. Multiple re-cloning of the white colonies grown with MNPs showed that they retained their properties both under standard conditions (temperature of 24 °C) and at the temperatures up to 37o C. E.nigrum grown with MNPs demonstrated very scant extension of small colonies at the cultivation temperature of 24o C, their growth was completely blocked at 37°C. Significant changes in the structure of the population were noted. First of all, large cells with pronounced aggregation were observed among the black colonies. These aggregates consisted of large cells connected to each other by matrix. In the white colonies the appearance of very long threadlike cells connecting different groups of the cells establishing an intercellular communication was evident. Fe2O3 MNPs induce an increase in the heterogeneity of the population, expressed as a change in morpho-physiological states.
Biomedical applications of nanoparticles require deep understanding of their interaction with normal human microflora. Previously, the toxic and mutagenic properties of iron oxide nanoparticles as well as their effect on the growth and morphology of the microflora were extensively investigated. However, the studies related to the variability of microbial pathogenicity factors induced by iron oxide nanoparticles are very limited. Meanwhile, this characteristic of microbes is genetically determined and is important for their survival and distribution in the human body. Therefore, pathogenicity factors are significant indicators of the experimental studies. In this work, the effect of the presence of Fe2O3 nanoparticles obtained by laser target evaporation (LTE) on selected enzymes that demonstrate invasion and aggression factors was evaluated for three reference strains of Candida albicans, Staphylococcus aureus, and Escherichia coli. It was found that the presence of LTE Fe2O3 nanoparticles supplied in the form of water-based suspensions does not induce changes of the above-mentioned parameters.
The level of variability of the E.coli morphotype under the influence of iron oxide nanoparticles (MNPs) depending on their concentration was studied as well as the adaptive capabilities of the microbial population under growth conditions was evaluated.The presence of γ-Fe2O3 nanoparticles in the cultivation fluid affects the cultural and morphological properties of the microbial population of E.coli in the process of its development. The appearance of new morphotypes of colonies and cells can be considered as a manifestation of an adaptive mechanism. A change in the morphology of the microbial cell with a high concentration of MNPs leads to abnormal growth and disruption of the division process.
The article describes the features of hardening metal matrix composite materials with the implementation of small amounts of nano-sized reinforcing additives.
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