Svetlana P. Chebotaryova

This study investigated the concentration-dependent effects of zinc oxide nanoparticles (ZnO NPs, 30–70 nm) on the freshwater microalga Lobosphaera sp. under different salinity conditions (0–4 g L⁻¹ NaCl). ZnO NPs demonstrated dual effects: low concentration (0.75 mg L⁻¹) enhanced growth and alleviated salt stress, while higher concentrations (7.5–75 mg L⁻¹) caused significant growth inhibition (up to 52%) and induced oxidative stress. Salinity did not significantly affect NPs aggregation patterns, and neither salinity nor aggregation degree influenced toxicity outcomes. NPs concentration plays a dominant role of toxicological effects. Dose-dependent increases in catalase activity and ROS-positive cells confirmed NPs-induced oxidative stress. Crucially, zinc bioaccumulation correlated with NPs concentration but dissociated from dissolved Zn²⁺ release, demonstrating particle-driven toxicity. Our findings challenge the ion-release paradigm and highlight the potential of low-dose ZnO nanoparticles as effective stress-protectors in algal biotechnology, offering new strategies for enhancing microalgal resilience under environmental stress.

Copper (II) oxide nanoparticles (CuO NPs) attract much attention as a promising antimicrobial agent. We studied the antibacterial properties of three types of CuO NPs against Escherichia coli bacteria: flake-shaped particles with a diameter of 50–200 nm and a thickness of 10–20 nm (CuO-CD synthesized by chemical deposition), spherical particles with a size of 20–90 nm (CuO-EE obtained by electrical explosion), and rod-shaped particles with a length of 100–200 nm and a diameter of 30 × 70 nm (CuO-CS commercial sample). We tested how the shape, size, and concentration of the NPs, and composition of the dispersion medium affected the properties of the CuO NPs. We prepared dispersions based on distilled water, a 0.9% NaCl solution, and the LB broth by Lennox and used Triton X-100 and sodium dodecyl sulfate (SDS) as stabilizers. The concentration of NPs was 1–100 mg L⁻¹. We showed that the dispersion medium composition and stabilizer type had the greatest influence on the antibacterial effects of CuO NPs. We observed the maximum antibacterial effect for all CuO NP types dispersed in water without a stabilizer, as well as in LB broth with the SDS stabilizer. The maximum inhibition of culture growth was observed under the influence of CuO-EE (by 30%) and in the LB broth with the SDS stabilizer (by 1.3–1.8 times depending on the type of particles). In the saline solution, the antibacterial effects were minimal; in some cases, the CuO NPs even promoted bacterial culture growth. SDS increased the antibacterial effects of NPs in broth and saline but decreased them in water. Finally, among the particle types, CuO-CS turned out to be the most bactericidal, which is probably due to their rod-shaped morphology and small diameter. At the same time, the concentration and aggregation effects of CuO NPs in the colloidal systems we studied did not have a linear action on their antibacterial properties. These results can be used in the development of antibacterial coatings and preparations based on CuO NPs to achieve their maximum efficiency, taking into account the expected conditions of their use.

An unknown species of the diatom genus Paraplaconeis was discovered during a field study of freshwater environments in Central Mongolia. In the course of further study, two monoclonal strains were acquired for the unknown species. The strains were utilized for molecular-genetic analysis on SSU rRNA and rbcL genes. As a result of the molecular investigation and careful morphological examination of valve structure with light and scanning electron microscopy, we propose the description of a new species—Paraplaconeis dorofeyukae sp. nov.—in this article. The new species is morphologically compared to similar taxa from the Paraplaconeis placentula group. Paraplaconeis dorofeyukae sp. nov. can be distinguished from related species by a combination of valve dimensions, morphology of apices and central area, and external valve ultrastructure.

The study is the first to examine the combined use of blast-furnace sludge as a source of microelements and converter slag as a soil-deoxidizing agent in oat (Avena sativa L.) cultivation in sod-podzolic soils. It has been established that blast-furnace sludge is a highly dispersed waste, which contains about 50% iron, 7% zinc, and a small amount of calcium, silicon, magnesium, aluminum, and sulfur. Hazardous components such as lead, arsenic, etc., are not detected. Converter slag comprises porous granules up to 3 mm in size, consisting mainly of calcium compounds (CaO, Ca(CO)₃, CaSiO₃, CaFe₂O₄) and a small amount of Mn, Al, and Mg trace elements. In a laboratory experiment, blast-furnace sludge increased the germination of oats by 5–10%, regardless of the addition of a deoxidizer (slag), but at the same time suppressed the growth of stem length by a maximum of 18% at 1 g∙kg⁻¹. The addition of slag raised substrate pH and increased the index by 8% at a sludge concentration of 0.1 g∙kg⁻¹. Root length in deoxidizer-free variants increased by 50–60% and with the addition of slag by 27–47%. Root dry mass also increased under the addition of sludge by 85–98%; however, the addition of slag reduced the indicator to the control level. In a field experiment with the combined application of waste, an increase in yield by more than 30% was shown. When soil was treated with slag and sludge, the height of plants increased by an average of 18%. It should be noted that the introduction of waste did not affect the quality of the grain. The use of slag increased the lead content in the soil, which is probably due to the sorption properties of calcium compounds in the slag, since lead was not found in the analyzed waste. Presumably, lead is sorbed by slag from the lower soil horizons, concentrating and immobilizing it in the upper layer. This version is supported by the absence of lead accumulation in straw and oat grain. The zinc-containing sludge increased the content of this element by 33% in the soil, as well as by 6% in straw and by 14% in grain. Thus, we found that the studied metallurgical wastes can be used as nutrients for agriculture, both individually and jointly. Overall, the proposed approach will contribute both to reducing the amount of accumulated waste and to improving the efficiency and sustainability of agricultural production and CO₂ sequestration. However, the features of the accumulation of heavy metals in soil and plants under the influence of the analyzed types of waste require more in-depth study, including within the framework of long-term field experiments.

Currently, the development of technologies to improve the efficiency of existing micropropagation techniques remains relevant. This work contains the results of studying the effects of Ag nanoparticles (NPs) of spherical shape (20–40 nm) and CuO of flocculent morphology (diameter 50 to 200 nm, thickness 10–20 nm) on brittle willow plants and the assessment of their biological effects using the method of clonal micropropagation. At the multiplication stage, Ag and CuO NPs at a concentration of 3 μg/L increase the number of surviving and sterile microclones to 100%, and the shoot height was on average 27% higher than the control at concentrations of 1.5 and 3 μg/L. At the rooting stage, an increase in the number of rooted seedlings under the influence of Ag is noted. In in vivo experiments, brittle willow seedlings treated with a Ag solution at a concentration of 3 μg/L have the best resistance to nonsterile greenhouse conditions. The number of surviving microclones is 7% higher than the control values and the number of established plants is 27% higher. The height of the plants after 3 weeks is 5.3 cm, while for the control this figure is 4.8 cm. This study shows the prospects for using the studied NPs to stimulate the growth and development of willow plants in vitro and in vivo.

The wide practical application of carbon nanomaterials (CNM) is limited by their potential ecological toxicity, various aspects of which remain debatable. This work assesses the effect of graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) on the growth, viability, oxidative stress, and content of photosynthetic pigments in the cells of a common microalga of the genus Desmodesmus. The study shows differences in the effects of different carbon nanomaterials at the same concentrations. Thus, GO does not have a negative effect on the viability and cell growth of the microalga Desmodesmus armatus with the exception of an increase in the level of oxidative stress, which ultimately affects growth of the culture. At the same time, when MWCNTs are added at concentrations of 100 and 1000 μg/L, a significant decrease in the growth of the cell number is recorded already on the 7th day of the experiment, with the effect maintained at the end of the experiment (14th day). At the same concentrations, a significantly higher level of oxidative stress is observed on the 14th day of the experiment. The analyzed CNMs do not have a reliable effect on the content of photosynthetic pigments. Thus, in the studied concentrations, GO turns out to be practically safe for the studied microalgae, unlike MWCNTs, which show noticeable toxicity. This can be taken into account in the future when developing practical applications for such CNMs, and can also be used in environmental regulation of their content in the environment.

The removal of pollutants, including heavy metals, from the aquatic environment is an urgent problem worldwide. Actively developing nanotechnology areas is becoming increasingly important for solving problems in the field of the remediation of aquatic ecosystems. In particular, methods for removing pollutants using nanoparticles (NPs) are proposed, which raises the question of the effect of a combination of NPs and heavy metals on living organisms. In this work, we investigated the role of CuO-NPs in changing the toxicity of Cd and Pb salts, as well as the bioaccumulation of these elements in a culture of the microalga Desmodesmus communis. It was found that CuO-NPs at concentrations of 10, 100, and 1000 µg L⁻¹ had no effect on the viability of microalgae cells. On the 14th day of the experiment, Cd at a concentration of 1 mg L⁻¹ reduced the viability index by 30% and, when combined with CuO-NPs, by 25%, i.e., CuO-NPs slightly reduced the toxic effect of Cd. At the same time, in this experiment, when CuO-NPs and Cd were used together, the level of oxidative stress increased, including on the first day in mixtures with 1 mg L⁻¹ Cd. Under the influence of Pb, the cell viability index decreased by 70% by the end of the experiment, regardless of the metal concentration. The presence of CuO-NPs slightly reduced the toxicity of Pb in terms of viability and reactive oxygen species (ROS). At the same time, unlike Cd, Pb without NPs caused ROS production on the first day, whereas the addition of CuO-NPs completely detoxified Pb at the beginning and had a dose-dependent effect on mixtures at the end of the experiment. Also, the introduction of CuO-NPs slightly reduced the negative effect of Pb on pigment synthesis. As a molecular mechanism of the observed effects, we prioritized the provocation of oxidative stress by nanoparticles and related gene expression and biochemical reactions of algae cells. Analysis of the effect of CuO-NPs on the Cd and Pb content in microalgae cells showed increased accumulation of heavy metals. Thus, when algae were cultured in an environment with Cd and CuO-NPs, the Cd content per cell increased 4.2 times compared to the variant where cells were cultured only with Cd. In the case of Pb, the increase in its content per one cell increased 6.2 times when microalgae were cultured in an environment containing CuO-NPs. Thus, we found that CuO-NPs reduce the toxic effects of Cd and Pb, as well as significantly enhance the bioaccumulation of these toxic elements in the cells of D. communis microalgae. The results obtained can form the basis of technology for the nanobioremediation of aquatic ecosystems from heavy metals using microalgae.

The increasing demand for products manufactured using nanotechnology contributes to a major increase in the synthesis of nanoscale materials and their inflow into the aquatic environment. TiO₂ nanoparticles as micropollutants in the aquatic environment directly affect many living organisms with generally negative effects. Microalgae have proven efficacy in bioremediation, which makes them a potential agent for the bioremediation of nanoparticles from wastewater. Evaluation of the capacity of microalgae from the genus Desmodesmus for the bioaccumulation of TiO₂ nanoparticles is carried out and the degree of resistance of microalgae cells to the action of environmentally relevant concentrations of these nanoparticles is determined. Spherical TiO₂ nanoparticles with a size of 30–40 nm are used. It is found by flow cytometry that TiO₂ nanoparticles at concentrations of 10, 100, and 1000 μg/L have no significant effect on the viability of microalgae cells and level of oxidative stress. Nanoparticles at a concentration of 1000 µg/L increase the concentration of photosynthetic pigments by 18–33% by day 13 of the experiment. Desmodesmus sp. appears to be a culture relatively resistant to nanoparticles; the increased bioaccumulation of titanium by microalgae cells in the experimental groups is detected by ICP-MS. All this indicates the significant potential of Desmodesmus sp. for the removal of nanostructured pollutants from the aquatic environment.

In this work, we present an analysis of the antibacterial activity of TiS₃ nanostructures in water and 0.9% NaCl solution suspensions. TiS₃ nanoribbons 1–10 µm long, 100–300 nm wide, and less than 100 nm thick were produced by the direct reaction of pure titanium powder with elemental sulphur in a quartz tube sealed under vacuum. For the toxicity test of a bioluminescent strain of E. coli we used concentrations from 1 to 0.0001 g L⁻¹ and also studied fresh suspensions and suspensions left for 24 h. The strongest toxic effect was observed in freshly prepared water solutions where the luminescence of bacteria decreased by more than 75%. When saline solution was substituted for water or when the solutions were stored for 24 h it resulted in a considerable decrease in the TiS₃ antibacterial effect. The toxicity of TiS₃ in water exceeded the toxicity of the reference TiO₂ nanoparticles, though when saline solution was used instead of water the opposite results were observed. In addition, we did not find a relationship between the antibacterial activity of water suspensions of nanoribbons and the stability of their colloidal systems, which indicates an insignificant contribution to the toxicity of aggregation processes. In 0.9% NaCl solution suspensions, toxicity increased in proportion to the increase in the zeta potential. We suppose that the noted specificity of toxicity is associated with the emission of hydrogen sulphide molecules from the surface of nanoribbons, which, depending on the concentration, can either decrease or increase oxidative stress, which is considered the key mechanism of nanomaterial cytotoxicity. However, the exact underlying mechanisms need further investigation. Thus, we have shown an important role of the dispersion medium and the period of storage in the antibacterial activity of TiS₃ nanoribbons. Our results could be used in nanotoxicological studies of other two-dimensional nanomaterials, and for the development of novel antibacterial substances and other biomedical applications of this two-dimensional material.

Broad application of CuO nanoparticles (CuO-NP) for industrial and household purposes leads to a continuous increase in their discharge to, and, hence, ever-increasing environmental hazards for aquatic ecosystems. Microalgae-based technologies hold promise for bioremediation of diverse hazardous micropollutants (HMP), including NP, from wastewater. In this study, we tested the ability of the green microalga Desmodesmus sp. to accumulate CuO-NP or their components. We also assessed the tolerance of this microalga to the environmentally relevant concentrations of CuO-NP. Using scanning electron microscopy, we demonstrated that the average size of CuO-NP was 50–100 nm, and their purity was confirmed with elemental composition analysis. Tests of the colloidal suspensions of CuO-NP showed that the hydrodynamic diameter of CuO-NP and their aggregates was below 100 nm. Flow cytometry analysis showed that CuO-NP at a concentration of 100 µg L⁻¹ slightly inhibited the viability of microalgae cells and led to an increase in their oxidative stress. The assessment of the condition of photosystem II showed that CuO-NP exert a multifaceted effect on the photosynthetic apparatus of Desmodesmus sp., depending on the concentration of and the exposure to the CuO-NP. Desmodesmus sp. turned to be relatively tolerant to CuO-NP. In addition, the ICP-MS method revealed increased bioaccumulation of copper by microalgae cells in the experimental groups. The outcomes of this study indicate that the Desmodesmus sp. has a significant potential for bioremoval of the copper-based nanostructured HMP from an aquatic environment.