Toxicity investigation of CeO2 nanoparticles coated with glucose and exopolysaccharides levan and pullulan on the bacterium Vibrio fischeri and aquatic organisms Daphnia magna and Danio rerio

Mechanochemical remediation of fluoranthene contaminated soil and biotoxicity evaluation

A mechanochemical (MC) method was employed for the remediation of soil contaminated with fluoranthene (C₁₆H₁₀, FL) a four-ringed polycyclic aromatic hydrocarbon (PAH) containing three benzene rings and a central five-membered heterocyclic ring, with the effects of soil inorganic components, milling conditions, and the degradation mechanism investigated. Results showed that the addition of SiO₂ and kaolin to soil resulted in a greater increase in the effectiveness of FL removal than other inorganic additives. After 3 hours of milling at 500 rpm, the FL removal rate from SiO₂ containing soil, reached 99.26%, with the removal efficiency increasing in accordance with an increase in milling duration and speed. The milled samples were characterized by FT-IR, Raman spectroscopy, and GC-MS analysis, revealing the mechanism of FL degradation, including destruction of the aromatic skeleton structure and the formation of amorphous carbon and graphite. The MC remediation method was applied to FL contaminated soil, showing that FL was efficiently degraded in soil without any soil additives, resulting in a significant reduction in the biotoxicity of the remediated soil. The organic matter, moisture content and pH of the actual soil changed slightly after mechanical ball milling. Thus, the MC method has high potential in the remediation of PAH-contaminated soils.HIGHLIGHTSA mechanochemical (MC) method for the degradation of fluoranthene was assessed.The use of silica and kaolin as soil additives enhances fluoranthene remediation.Fluoranthene can be efficiently removed from contaminated soil by milling alone.The degradation mechanism was skeleton structure destruction and carbonization.The biotoxicity of soil was significantly reduced by milling.

A brief study on the role of cerium oxide nanoparticles in growth and alleviation of mercury-induced stress in Vigna radiata and soil bacteria Bacillus coagulans

Cerium oxide nanoparticles have so far been investigated for their role as an antioxidant in pathologies involving inflammation and high oxidative stress. However, its role as a plant and bacterial growth modulator and heavy metal stress reliever has been overlooked to date. Heavy metal contamination poses a major threat to mankind and the life-sustaining ecosystem. This study emphasizes the role of cerium oxide produced by the combustion method in promoting growth in Vigna radiata and Bacillus coagulans in the presence of mercury. The results show that cerium oxide nanoparticles significantly reduce the production of reactive oxygen species, hydrogen peroxide, and product of lipid peroxidation malondialdehyde in plants grown in the presence of 50 ppm mercury, thereby reducing oxidative stress. Nanoceria also increases plant growth with respect to those growing solely in mercury. Nanoceria alone does not significantly affect the growth of Vigna radiata as well as Bacillus coagulans and Escherichia coli, thereby proving its non-hazardous nature. It also significantly increases the growth of Bacillus coagulans at 25 ppm and 50 ppm of mercury. This study throws light upon the biologically non-hazardous nature of this particle by revealing how it promotes the growth of two soil bacteria Bacillus coagulans and E.coli at various dosages. The results of this study pave the way for the use of cerium oxide nanoparticles in plants and various other organisms to combat abiotic stress.

Trans-generational effect of cerium oxide-nanoparticles (nCeO2) on Chenopodium rubrum L. and Sinapis alba L. seeds

Cerium oxide nanoparticles (nCeO2 ) are interesting nanomaterials due to their redox properties. Their wide application could result in unexpected consequences to environmental safety. Unlike acute toxicity, the trans-generational effects of carbohydrate-coated nCeO2 in the environment are still unknown. The main aim of this study was to investigate the effect of treating maternal plants of Chenopodium rubrum L. (red goosefoot) and Sinapis alba L. (white mustard) with uncoated (CeO2 ) and glucose-, levan-, or pullulan-coated nCeO2 (G-, L-, or P-CeO2 ) during seed germination on morphological and physiological characteristics of produced seeds in two subsequent generations. The plant response was studied by measuring germination percentage (Ger), total protein content (TPC), total phenolic content (TPhC), total antioxidative activity (TAA), and catalase (CAT) activity. Results showed that maternal effects of the different nCeO2 treatments persist to at least the second generation in seeds. Generally, C. rubrum was more sensitive to nCeO2 treatments than S. alba . The coated nCeO2 were more effective than uncoated ones in both plant species; L- and P-CeO2 were the most effective in S. alba , while CeO2 and G-CeO2 had a dominant impact in C. rubrum . Enhanced germination in all tested generations of S. alba seeds recommends nCeO2 for seed priming.

Correlation between BOD/COD Ratio and Octanol/Water Partition Coefficient for Mixture Organic Compounds

Correlation between the BOD/COD ratio and Partition coefficient of octanol/ water (Pow) on a single organic substance shows that the Pow value is directly proportional to the toxicity level and inversely proportional to BOD/COD ratio. This research examined the correlation to a mixture of organic substances. The objective is to obtain a varied range of substances, as well as determining the quality of wastewater discharging to fresh waters. Need for analysis of organic substances used as antiseptics during the Covid-19 pandemic. In addition, organic substances from the organophosphate pesticide class, diazinon, were used. BOD5, COD, Pow, and LC50-96h toxicity tests using Daphnia magna were used. Six types of the mixture of organic substances included diazinon-formaldehyde-isopropyl alcohol, ethanol-oxalic acid-formaldehyde, isopropyl alcohol-glycerol-lactose, acetic acid-isopropyl alcohol-formaldehyde, sucrose-glycerol-acetic acid, and oxalic acid-formaldehyde-diazinon, with 3 different concentrations of 10, 100, and 1000 mg/L, three repetitions. The lowest BOD/COD ratio (<0.2) and the highest Pow value (>4) are found in diazinon-formaldehyde-IPA. Its toxicity in D. magna also showed the lowest LC-50 (11.82 mg/L). Whereas, sucrose-glycerol-acetic acid had the highest BOD/COD ratio (>0.7) and lowest Pow (<0.7) with the highest LC- 50 (567.88 mg/L). Other organic substances mixtures have characteristics in the range of these mixtures. Pow variability and the BOD/COD ratio have a negative correlation. A mixture of organic matter is more biodegradable making it has a higher tendency to dissolve in water.

Assessment of hazardous impact of nickel oxide nanoparticles on biochemical and histological parameters of gills and liver tissues of Heteropneustes fossilis

BACKGROUND

The aim of the present study was to assess the hazardous impact of nickel oxide nanoparticles (NiO NPs) on gills and liver of Heteropneustes fossilis.

METHODS

Fishes were treated with four concentrations of NiO NPs for a period of 14 days. Nickel accumulation, lipid peroxidation, antioxidant enzymes activities (superoxide dismutase, catalase, glutathione s transferase & glutathione reductase), liver enzymes activities (aspartate amino transferase, alanine transaminase, & alkaline phosphatase), Na⁺/K⁺ ATPase activity, FTIR, metallothionein content, ethoxyresorufin-o-deethylase activity, immunohistochemistry, histology and scanning electron microscopy were analyzed in both gills and liver tissues.

RESULTS

Results revealed increased accumulation of nickel in both the tissues of exposed fishes. Lipid peroxidation and activities of different antioxidant enzymes increased (except superoxide dismutase) in both the tissues after exposure. Fluctuations in liver enzymes activities and variation in the activity of Na⁺/K⁺ ATPase were also observed. FTIR data revealed shift in peaks position in both the tissues. Level of metallothionein and its expression as well as activity of ethoxyresorufin-o-deethylase and expression of CYP1A also increased in both the target tissues of treated fishes. Furthermore, histological investigation and scanning electron microscopy showed structural damages in gills as well as liver tissues of exposed fishes.

CONCLUSION

Our results suggest that NiO NPs cause deteriorating effects on the gill and liver tissues of fish, therefore effluents containing these nanoparticles should be treated before their release into water bodies.

Nanostructured Ceria: Biomolecular Templates and (Bio)applications

Ceria (CeO2) nanostructures are well-known in catalysis for energy and environmental preservation and remediation. Recently, they have also been gaining momentum for biological applications in virtue of their unique redox properties that make them antioxidant or pro-oxidant, depending on the experimental conditions and ceria nanomorphology. In particular, interest has grown in the use of biotemplates to exert control over ceria morphology and reactivity. However, only a handful of reports exist on the use of specific biomolecules to template ceria nucleation and growth into defined nanostructures. This review focusses on the latest advancements in the area of biomolecular templates for ceria nanostructures and existing opportunities for their (bio)applications.