Toxicological Impacts of TiO2 Nanoparticles on Growth, Photosynthesis Pigments, and Protein and Lipid Content of the Marine Microalga Tetraselmis Suecica

On how titanium dioxide nanoparticles attenuate the toxicity of mercuric chloride to Artemia salina: investigation of fatty acid composition, oxidative stress, and lipid peroxidation

Titanium dioxide nanoparticles (TiO2NPs) as an emerging pollutant in aquatic environments can interact with metals reducing or enhancing their toxicity in these environments. This study examined and compared the toxic effects of mercury ions (Hg2+ ions) on immobilization percentage, fatty acid profile, and oxidative stress of Artemia salina nauplii, individually (Hg) and simultaneously in the presence of 0.10 mg.L-1 (Hg-0.1TiO2NPs) and 1.00 mg.L-1 TiO2NPs (Hg-1TiO2NPs). The interaction between Hg2+ ions and TiO2NPs was evaluated using DLS and AAS-VGA. Simultaneous exposures exhibited an unexpected dual effect on A. salina nauplii. A synergistic effect was observed in Hg-0.1TiO2NPs, while increasing the TiO2NPs concentration in Hg-1TiO2NPs prevented the synergy of the mixture compounds offering an antagonistic effect on nauplii. This dual effect was assigned to a greater number of available active sites and agglomeration of TiO2NPs at higher concentrations. Oxidative stress and lipid peroxidation induced by Hg were diminished in Hg-1TiO2NPs in line with the immobilization results. In Hg, total amounts of saturated fatty acids (∑SFA) increased while total monounsaturated (∑MUFA) and total polyunsaturated (∑PUFA) ones decreased compared with the control. However, they showed no significant change considering the control in Hg-1TiO2NPs, again confirming the antagonistic effect on nauplii. The unsaturated to saturated fatty acids ratio decreased in both Hg and Hg-1TiO2NPs compared with the control, however, this reduction in Hg-1TiO2NPs was lower than in Hg. The present results emphasized getting a more comprehensive understanding of how TiO2NPs impact the bioavailability and toxicity of co-contaminants through their combined effects and interactions.

Disposable face masks into aquatic media: Chemical and biological testing of the released compounds during the leaching process

The present study investigated the fate, and the biological effects posed by the presence of Disposable Face Masks (DFMs) into fresh- and saltwater media, using both chemical and biological testing. To this end, slightly fragmented DFMs were maintained in tanks with artificial sea water (ASW) or dH2O (DFMASW and DFMdH2O, respectively) for a period of 20 days (under continuous agitation, oxygen supply, and light/dark ration 1:1) to simulate both fresh- and saltwater natural conditions. Thereafter, DFMs leaching substances were determined, before proceeding to biological testing with the use of the marine bacterium Aliivibrio fischeri (Bioluminescence Inhibition assay), the fresh- and saltwater algal species Chlorococcum sp. and Tetraselmis suecica (algal bioassays), as well as the fairy shrimp Thamnocephalus platyurus, the water flea Daphnia magna, and the rotifer Brachionus calyciflorus (acute toxicity screening tests, in terms of microbiotest). According to the results, once into aquatic media (DFMASW and DFMdH2O) DFMs are subjected to degradation, leading to the release of organic, inorganic, and polymeric compounds (PP microfibers). Considering that possible interactions of the leaching substances could differentially affect the aquatic biota, the present study showed that DFMs leaching substances could be harmful to the fairy shrimp T. platyurus, and the water flea D. magna, with slight to non-toxic effects to be observed in case of Chlorococcum sp. and Tetraselmis suecica, the marine bacterium Aliivibrio fischeri, and the rotifer B. calyciflorus. The present findings showed that the DFMs improper disposal into fresh- and/or saltwater media, followed by their degradation and leaching processes, could lead to the release of substances of great environmental concern, thus promoting awareness about their proper handling and management, as well as the long-term monitoring of their environmental risk.

Mechanistic Insights into Toxicity of Titanium Dioxide Nanoparticles at the Micro- and Macro-levels

Titanium oxide nanoparticles (TiO2 NPs) have been regarded as a legacy nanomaterial due to their widespread usage across multiple fields. The TiO2 NPs have been and are still extensively used as a food and cosmetic additive and in wastewater and sewage treatment, paints, and industrial catalysis as ultrafine TiO2. Recent developments in nanotechnology have catapulted it into a potent antibacterial and anticancer agent due to its excellent photocatalytic potential that generates substantial amounts of highly reactive oxygen radicals. The method of production, surface modifications, and especially size impact its toxicity in biological systems. The anatase form of TiO2 (<30 nm) has been found to exert better and more potent cytotoxicity in bacteria as well as cancer cells than other forms. However, owing to the very small size, anatase particles are able to penetrate deep tissue easily; hence, they have also been implicated in inflammatory reactions and even as a potent oncogenic substance. Additionally, TiO2 NPs have been investigated to assess their toxicity to large-scale ecosystems owing to their excellent reactive oxygen species (ROS)-generating potential compounded with widespread usage over decades. This review discusses in detail the mechanisms by which TiO2 NPs induce toxic effects on microorganisms, including bacteria and fungi, as well as in cancer cells. It also attempts to shed light on how and why it is so prevalent in our lives and by what mechanisms it could potentially affect the environment on a larger scale.

Ionic and nanoparticulate silver alleviate the toxicity of inorganic mercury in marine microalga Chaetoceros muelleri

Toxicological effects of silver nanoparticles (SNPs) in different organisms have been studied; however, interactions of SNPs with other environmental pollutants such as mercury are poorly understood. Herein, bioassay tests were performed according to ΟECD 201 guideline to assess the toxic effects induced by mercury ions (mercury chloride, MCl) on the marine microalga Chaetoceros muelleri in the presence of SNPs or silver ions (silver nitrate, SN). Acute toxicity tests displayed that the presence of SNPs or SN (0.01 mg L-1) significantly reduced the toxicity of MCl (0.001, 0.01, 0.1, 1, 10, and 100 mg L-1) and increased the IC50 of MCl from 0.072 ± 0.014 to 0.381 ± 0.029 and 0.676 ± 0.034 mg L-1, respectively. In the presence of SN or SNPs, the mercury-reducing effect on algal population growth significantly decreased. Considering the increase of IC50, the mercury toxicity decreased approximately 5.44 and 9.66 times in the presence of SNPs or SN, respectively. The chlorophyll a and c contents decreased at all exposures; however, the decrease by MCl-SNPs and MCl-SN was significantly less than MCl except at 1 mg L-1. The lowering effect of MCl-SN on chlorophyll contents was less than MCl and MCl-SNPs. MCl exposure induced significant raises in total protein content (TPC) at concentrations < 0.01mg  L-1, with a maximum of ~ 70.83% attained at 100 mg L-1. The effects of MCl-SNPs and MCl-SN on TPC were significantly less than MCl. Total lipid content (TLC) at all MCl concentrations was higher than the control, while at coexposure to MCl-SN, TLC did not change until 0.01 mg L-1 compared with the control. The effects of MCl-SN and MCL-SNPs on TPC and TLC were in line with toxicity results, and were significantly less than those of MCl individually, confirming their antagonistic effects on MCl. The morphological changes of algal cells and mercury content of the cell wall at MCl-SN and MCl-SNPs were mitigated compared with MCl exposure. These findings highlight the mitigatory impacts of silver species on mercury toxicity, emphasizing the need for better realizing the mixture toxicity effects of pollutants in the water ecosystem.

Impact of nanopollution on plant growth, photosynthesis, toxicity, and metabolism in the agricultural sector: An updated review

Nanotechnology provides distinct benefits to numerous industrial and commercial fields, and has developed into a discipline of intense interest to researchers. Nanoparticles (NPs) have risen to prominence in modern agriculture due to their use in agrochemicals, nanofertilizers, and nanoremediation. However, their potential negative impacts on soil and water ecosystems, as well as plant growth and physiology, have caused concern for researchers and policymakers. Concerns have been expressed regarding the ecological consequences and toxicity effects associated with nanoparticles as a result of their increased production and usage. Moreover, the accumulation of nanoparticles in the environment poses a risk, not only because of the possibility of plant damage but also because nanoparticles may infiltrate the food chain. In this review, we have documented the beneficial and detrimental effects of NPs on seed germination, shoot and root growth, plant biomass, and nutrient assimilation. Nanoparticles exert toxic effects by inducing ROS generation and stimulating cytotoxic and genotoxic effects, thereby leading to cell death in several plant species. We have provided possible mechanisms by which nanoparticles induce toxicity in plants. In addition to the toxic effects of NPs, we highlighted the importance of nanomaterials in the agricultural sector. Thus, understanding the structure, size, and concentration of nanoparticles that will improve plant growth or induce plant cell death is essential. This updated review reveals the multifaceted connection between nanoparticles, soil and water pollution, and plant biology in the context of agriculture.