Organic and inorganic nano-Fe3O4: Alga Ulva flexuosa-based synthesis, antimicrobial effects and acute toxicity to briny water rotifer Brachionus rotundiformis

A facile strategy for preparation of Fe3O4 magnetic nanoparticles using Cordia myxa leaf extract and investigating its adsorption activity in dye removal

This study demonstrates the successful, facile, and cost-effective preparation of magnetic Fe3O4 nanoparticles (MNPs) via green procedure using Cordia myxa leaf extracts for efficient adsorption of methylene blue (MB) as a model of organic pollutant. The formation of Fe3O4 NPs was confirmed by a range of spectroscopy and microscopy techniques including FT-IR, XRD, FE-SEM, TEM, EDS, VSM, TGA, and BET-BJH. The synthesized spherical nanoparticles had a high specific surface area of 115.07 m2/g with a mesoporous structure. The formed Fe3O4 MNPs exhibited superparamagnetic behavior with saturation magnetization of 49.48 emu/g. After characterization, the adsorptive performance of the synthesized MNPs toward MB was evaluated. To achieve the maximum removal efficiency, the effect of key parameters such as adsorbent dosage (MNPs), initial adsorbate concentration, pH, and contact time on the adsorption process was evaluated. A maximum adsorption capacity of 17.79 mg/g was obtained, after one-hour incubation at pH 7.5. From the pHPZC of 7.1 of the synthesized adsorbent, the electrostatic attraction between MB and Fe3O4 NPs plays an important role in the adsorption process. The adsorption experimental data showed the closest match with the pseudo-second-order kinetic and Langmuir isotherm. The prepared Fe3O4 NPs were easily recovered by an external magnet and could be reused several times. Therefore, the synthesized MNPs seem to be excellent adsorbents for the removal of MB from aqueous solution.

Macroalgae as biofactories of metal nanoparticles; biosynthesis and food applications

Nanotechnology has opened a new frontier in recent years, capable of providing new ways of controlling and structuring products with greater market value and offering significant opportunities for the development of innovative applications in food processing, preservation, and packaging. Macroalgae (MAG) are the major photoautotrophic group of living beings known as a potential source of secondary metabolites, namely phenolic compounds, pigments, and polysaccharides. Biosynthesis based on the abilities of MAG as "nanobiofactories" targets the use of algal secondary metabolites as reducing agents to stabilize nanoparticles (NPs). Nowadays, most of the studies are focused on the use of metal (Ag, Au) and metal-oxide (CuO, ZnO) NPs derived from algae. The eco-friendly biosynthesis of metal NPs reduces the cost and production time and increases their biocompatibility, due to the presence of bioactive compounds in MAG, making them suitable for a wide variety of applications. These compounds have been attributed to the antimicrobial and antioxidant properties responsible for their application through innovative technologies such as nanoencapsulation, nanocomposites, or biosensors in the food industry. Nevertheless, toxicity is a key factor that should be considered, so the applicable regulation needs to guarantee the safe use of metal NPs. Consequently, the aim of this review will be to compile the available information on MAG-mediated metal NPs, their biosynthesis, and potential food applications.

As (III) removal using superparamagnetic magnetite nanoparticles synthesized using Ulva prolifera - optimization, isotherm, kinetic and equilibrium studies

In this study, magnetite nanoparticles (MNPs) were synthesized using the seaweed - Ulva prolifera, an amply found marine source in the Western coastal regions of India. The surface and other properties of MNPs were characterized by many sophisticated methods. Spherical nanoclusters were observed in the FESEM image and iron and oxygen elements were seen in EDS results. XRD peaks were consistent with magnetite standards and MNPs had good crystallinity. FTIR portrayed the specific signals for MNPs and TGA profile ascertained the thermal stability. Magnetic saturation of 41.84 emu/g with negligible hysteresis loop substantiated the superparamagnetism. XPS pointed out the presence of Fe and O with oxidation states specific for MNPs, and the results were consistent with EDS. BET revealed a high specific surface area (144.98 m²/g) of MNPs with mesopores. The synthesized MNPs were used as nanoadsorbent for the removal of As (III) from aqueous solution. The central composite design was used for optimizing As (III) adsorption on MNPs. The optimum conditions were found out as 97.5% at pH: 9, rotation speed: 150 rpm, time: 90 min, and MNPs dosage: 1.15 g/L. The adsorption process fitted in a better way with the Langmuir isotherm and pseudo-second-order model. The highest adsorption capacity was 12.45 mg/g, which is substantially larger than the documenter reports. The spontaneous and endothermic nature of adsorption were ascertained from thermodynamic studies. The results suggested that the synthesized MNPs using the extract of U. prolifera could be alternative nanoadsorbents for eliminating toxic heavy metals from waste streams.

Study on Biogenic Spindle-Shaped Iron-Oxide Nanoparticles by Pseudostaurosira trainorii in Field of Laser Desorption/Ionization Applications

Nanostructures-assisted laser desorption/ionization mass spectrometry (NALDI-MS) is gaining attention for the analysis of a wide range of molecules. In this present investigation, Pseudostaurosira trainorii mediated biosynthesized iron-oxide nanoparticles (IONPs) have been utilized as nanostructures assisting ionization and desorption for laser desorption/ionization mass spectrometry (LDI-MS). The chain forming diatom, P. trainorii showed efficiency in the production of IONPs against 0.01 M Fe+3 (pH 2) aqueous solution at the intracellular and extracellular level. The whole biomass and external media turned dark orange in color after 3 days of reaction with Fe3+ solution. Scanning electron microscopic (SEM) images illustrated that the surface of Fe3+ exposed frustules of P. trainorii were entirely covered by synthesized nanostructures contrasting with the natural surface ornamentation of control cells. The IONPs loaded frustules also exhibited catalytic properties by decolorizing yellow colored nitrophenol after 3 h of reaction. Transmission electron microscopic (TEM) images confirmed that the produced particles are spindle-shaped with ~50–70 nm length and ~10–30 nm width. The biogenic IONPs were utilized as an inorganic matrix in LDI-MS and showed high sensitivity towards small molecules as glucose, alanine and triacylglycerols at nano- and picomolar level per spot, respectively. The presented biocompatible technique offers new perspectives in nanobiotechnology for the production of spindle-shaped IONPs that can be applied in future for the preparation of NALDI plates.

Iron Oxide Nanoparticles-Plant Insignia Synthesis with Favorable Biomedical Activities and Less Toxicity, in the “Era of the-Green”: A Systematic Review

In the era of favoring environment-friendly approaches for pharmaceutical synthesis, “green synthesis” is expanding. Green-based nanomedicine (NM), being less toxic and if having biomedical acceptable activities, thence, the chemical methods of synthesis are to be replaced by plants for reductive synthesis. Iron oxide nanoparticles (IONPs) exhibited remarkable anti-microbial and anti-cancer properties, besides being a drug delivery tool. However, owing to limitations related to the chemical synthetic method, plant-mediated green synthesis has been recognized as a promising alternative synthetic method. This systematic review (SR) is addressing plant-based IONPs green synthesis, characteristics, and toxicity studies as well as their potential biomedical applications. Furthermore, the plant-based green-synthesized IONPs in comparison to nanoparticles (NPs) synthesized via other conventional methods, characteristics, and efficacy or toxicity profiles would be mentioned (if available). Search strategy design utilized electronic databases including Science Direct, PubMed, and Google Scholar search. Selection criteria included recent clinical studies, available in the English language, published till PROSPERO registration. After screening articles obtained by first electronic database search, by title, abstract and applying the PICO criteria, the search results yielded a total of 453 articles. After further full text filtrations only 48 articles were included. In conclusion, the current SR emphasizes the perspective of the IONPs plant-mediated green synthesis advantage(s) when utilized in the biomedical pharmaceutical field, with less toxicity.

Progress and prospects of applying carbon-based materials (and nanomaterials) to accelerate anaerobic bioprocesses for the removal of micropollutants

Carbon‐based materials (CBM), including activated carbon (AC), activated fibres (ACF), biochar (BC), nanotubes (CNT), carbon xenogels (CX) and graphene nanosheets (GNS), possess unique properties such as high surface area, sorption and catalytic characteristics, making them very versatile for many applications in environmental remediation. They are powerful redox mediators (RM) in anaerobic processes, accelerating the rates and extending the level of the reduction of pollutants and, consequently, affecting positively the global efficiency of their partial or total removal. The extraordinary conductive properties of CBM, and the possibility of tailoring their surface to address specific pollutants, make them promising as catalysts in the treatment of effluents containing diverse pollutants. CBM can be combined with magnetic nanoparticles (MNM) assembling catalytic and magnetic properties in a single composite (C@MNM), allowing their recovery and reuse after the treatment process. Furthermore, these composites have demonstrated extraordinary catalytic properties. Evaluation of the toxicological and environmental impact of direct and indirect exposure to nanomaterials is an important issue that must be considered when nanomaterials are applied. Though the chemical composition, size and physical characteristics may contribute to toxicological effects, the potential toxic impact of using CBM is not completely clear and is not always assessed. This review gives an overview of the current research on the application of CBM and C@MNM in bioremediation and on the possible environmental impact and toxicity.

Seaweed bioactive compounds: Promising and safe inputs for the green synthesis of metal nanoparticles in the food industry

Scientific research on developing and characterizing eco-friendly metal nanoparticles (NPs) is an active area experiencing currently a systematic and continuous growth. A variety of physical, chemical and more recently biological methods can be used for the synthesis of metal nanoparticles. Among them, reports supporting the potential use of algae in the NPs green synthesis, contribute with only a minor proportion, although seaweed was demonstrated to perform as a successful reducing and stabilizing agent. Thus, the first part of the present review depicts the up-to-date information on the use of algae extracts for the synthesis of metal nanoparticles, including a deep discussion of the certain advantages as well as some limitations of this synthesis route. In the second part, the available characterization techniques to unravel their inherent properties such as specific size, shape, composition, morphology and dispersibility are comprehensively described, to finally focus on the factors affecting their applications, bioactivity, potential toxic impact on living organisms and incorporation into food matrices or food packaging, as well as future prospects. The present article identifies the key knowledge gap in a systematic way highlighting the critical next steps in the green synthesis of metal NPs mediated by algae.

Progress and prospects of magnetic iron oxide nanoparticles in biomedical applications: A review

Nanoscience has been considered as one of the most substantial research in modern science. The utilization of nanoparticle (NP) materials provides numerous advantages in biomedical applications due to their unique properties. Among various types of nanoparticles, the magnetic nanoparticles (MNPs) of iron oxide possess intrinsic features, which have been efficiently exploited for biomedical purposes including drug delivery, magnetic resonance imaging, Magnetic-activated cell sorting, nanobiosensors, hyperthermia, and tissue engineering and regenerative medicine. The size and shape of nanostructures are the main factors affecting the physicochemical features of superparamagnetic iron oxide nanoparticles, which play an important role in the improvement of MNP properties, and can be controlled by appropriate synthesis strategies. On the other hand, the proper modification and functionalization of the surface of iron oxide nanoparticles have significant effects on the improvement of physicochemical and mechanical features, biocompatibility, stability, and surface activity of MNPs. This review focuses on popular methods of fabrication, beneficial surface coatings with regard to the main required features for their biomedical use, as well as new applications.

Biosynthesized magnetite nanoparticles as an environmental opulence and sustainable wastewater treatment

This review emphasizes the win-win one-pot valorization process of different waste biomass that composed of many biological macromolecules (e.g. polysaccharides, polyphenols, carbohydrates, lipids, enzymes, proteins, etc.) and other biomolecules (e.g. alkaloids, terpenoids, tannins, phenolics, carotenoids, amino acids, sugars, vitamins, etc.) into biofunctionalized magnetite (Fe₃O₄) nanoparticles (BMNPs). It illustrates the sustainable recruitment of microbial intra- and extra-cellular metabolites, proteins, and/or enzymes in the biosynthesis of BMNPs. It elucidates the environmental affluence of such sustainable, cost-effective, and ecofriendly BMNPs as an antimicrobial agent for water disinfection, photo-degrader, and adsorbent for different xenobiotics, organic and inorganic water pollutants. It confers the future environmental aspects of BMNPs in biofuels production from lipids and lignocellulosic wastes, biosensors manufacturing and bio-upgrading of petroleum fractions, etc. It discusses the circular economy, challenges, and opportunities for scaling up the zero-waste green synthesis of MNPs. Nevertheless, imminent investigations are still needed to elucidate the exact rule of biological macro- and micro- molecules in BMNPs synthesis and mechanisms involved in its microbicidal and photodegradation activities. Accentuated researches are more required on the toxicity and/or biosafety of the green synthesized BMNPs to humans and other non-target organisms to ensure its eco-safety upon environmental applications.

Evaluation of the environmental impact of magnetic nanostructured materials at different trophic levels

Safety on the use of magnetic nanomaterials (MNMs) has become an active topic of research given all the recent applications of these materials in various fields. It is known that the toxicity of MNMs depends on size, shape, and surface functionalization. In this study, we evaluate the biocompatibility with different aquatic organisms of engineered MNMs-CIT with excellent aqueous dispersion and long-term colloidal stability. Primary producers (the alga Pseudokirchneriella subcapitata), primary consumers (the rotifer Lecane papuana), and predators (the fish, Danio rerio) interacted with these materials in acute and sub-chronic toxicity tests. Our results indicate that P. subcaptita was the most sensitive taxon to MNMs-CIT. Inhibition of their population growth (IC₅₀ = 22.84 mg L^-1) elicited cell malformations and increased the content of photosynthetic pigments, likely due to inhibition of cell division (as demonstrated in AFM analysis). For L. papuana, the acute exposure to MNMs shows no significant mortality. However, adverse effects such as decreased rate of population and altered swimming patterns arise after chronic interaction with MNMs. For D. rerio organisms on early life stages, their exposure to MNMs results in delayed hatching of eggs, diminished survival of larvae, altered energy resources allocation (measured as the content of total carbohydrates, lipids, and protein), and increased glucose demand. As to our knowledge, this is the first study that includes three different trophic levels to assess the effect of MNMs in aquatic organisms; furthermore, we demonstrated that these MNMs pose hazards on aquatic food webs at low concentrations (few mgL^-1).

Targeted Delivery of Erythropoietin Hybridized with Magnetic Nanocarriers for the Treatment of Central Nervous System Injury: A Literature Review

Although the incidence of central nervous system injuries has continued to rise, no promising treatments have been elucidated. Erythropoietin plays an important role in neuroprotection and neuroregeneration as well as in erythropoiesis. Moreover, the current worldwide use of erythropoietin in the treatment of hematologic diseases allows for its ready application in patients with central nervous system injuries. However, erythropoietin has a very short therapeutic time window (within 6–8 hours) after injury, and it has both hematopoietic and nonhematopoietic receptors, which exhibit heterogenic and phylogenetic differences. These differences lead to limited amounts of erythropoietin binding to in situ erythropoietin receptors. The lack of high-quality evidence for clinical use and the promising results of in vitro/in vivo models necessitate fast targeted delivery agents such as nanocarriers. Among current nanocarriers, noncovalent polymer-entrapping or polymer-adsorbing erythropoietin obtained by nanospray drying may be the most promising. With the incorporation of magnetic nanocarriers into an erythropoietin polymer, spatiotemporal external magnetic navigation is another area of great interest for targeted delivery within the therapeutic time window. Intravenous administration is the most readily used route. Manufactured erythropoietin nanocarriers should be clearly characterized using bioengineering analyses of the in vivo size distribution and the quality of entrapment or adsorption. Further preclinical trials are required to increase the therapeutic bioavailability (in vivo biological identity alteration, passage through the lung capillaries or the blood brain barrier, and timely degradation followed by removal of the nanocarriers from the body) and decrease the adverse effects (hematological complications, neurotoxicity, and cytotoxicity), especially of the nanocarrier.

Response of soil microbial communities to engineered nanomaterials in presence of maize (Zea mays L.) plants

With the intended application of engineered nanomaterials (ENMs) in agriculture, accurate assessment the effect of these ENMs on soil microbial communities is especially necessary. Here, maize plants were cultivated in soil amended by SiO₂, TiO₂, and Fe₃O₄ ENMs (100 mg kg^-1 soil) for four weeks. The impact of ENMs on bacterial community structure of the rhizosphere soil was investigated by using high-throughput sequencing. In addition, metabolites of maize rhizosphere soil were quantified by gas chromatography-mass spectrometry (GC-MS) based metabolomics. We found that the disturbance of ENMs on soil microbes are in the follow of Fe₃O₄>TiO₂>SiO₂. Exposure of Fe₃O₄ ENMs significantly reduced the abundance of nitrogen-fixation related bacteria Bradyrhizobiaceae (from 2.94% to 2.40%) and iron-redox bacteria Sediminibacterium (from 2.15% to 2.07%). Additionally, Fe₃O₄ ENMs significantly increased populations of Nocardioides (from 1.63% to 1.77%), Chitinophaga sancti (from 1.12% to 2.08%), Pantoea (from 1.31% to 2.22%), Rhizobiumand (from 1.41% to 1.74%) and Burkholderia-Paraburkholderia (from 1.50% to 2.09%), which are associated with carbon cycling and plant growth promoting. This study provides a perspective on the response of rhizosphere microbial community and low molecular weight metabolites to ENMs exposure, providing a comprehensive understanding of the environmental risk of ENMs.

Biosynthesis of magnetic iron oxide nanoparticles: a review

Nanoparticles promise to revolutionize the way we think of ordinary materials thanks to the new features such small structures exhibit which include strength, durability, optical and magnetics properties. Magnetic iron oxide nanoparticles (IONPs) are a prominent class of NMs because of their potential application in magnetic separation, hyperthermia, targeted drug delivery, and catalysis. Most synthetic nanoparticulate platforms rely on the use of tough chemical procedures associated with unfriendly, harmful and costly reactants. For this reason, bio-inspired approaches have become the most successful alternatives to fabricate nanomaterials in an "eco-friendly" manner, and many bio-protocols that make use of substrates from plants and microorganisms have been successfully applied in the synthesis of magnetic IONPs. In this review, the main biosynthesis protocols applied in the synthesis of iron oxide nanoparticles are discussed. A discussion on the challenges for a second stage perspective which would be a large scale production is also given.

Algal metabolites: An inevitable substitute for antibiotics

Antibiotic resistance is rising at a pace that is difficult to cope with; circumvention of this issue requires fast and efficient alternatives to conventional antibiotics. Algae inhabit a wide span of ecosystems, which contributes to their ability to synthesize diverse classes of highly active biogenic metabolites. Here, for the first time, we reviewed all possible algal metabolites with broad spectra antibacterial activity against pathogenic bacteria, including antibiotic-resistant strains, and categorized different metabolites of both freshwater and marine algae, linking them on the basis of their target sites and mechanistic actions along with their probable nanoconjugates. Algae can be considered a boon for novel drug discovery in the era of antibiotic resistance, as various algal primary and secondary metabolites possess potential antibacterial properties. The diversity of these metabolites from indigenous sources provides a promising gateway enabling researchers and pharmaceutical companies to develop novel nontoxic, cost-effective and highly efficient antibacterial medicines.

Macroalgae as a Source of Valuable Antimicrobial Compounds: Extraction and Applications

In the last few decades, attention on new natural antimicrobial compounds has arisen due to a change in consumer preferences and the increase in the number of resistant microorganisms. Macroalgae play a special role in the pursuit of new active molecules as they have been traditionally consumed and are known for their chemical and nutritional composition and their biological properties, including antimicrobial activity. Among the bioactive molecules of algae, proteins and peptides, polysaccharides, polyphenols, polyunsaturated fatty acids and pigments can be highlighted. However, for the complete obtaining and incorporation of these molecules, it is essential to achieve easy, profitable and sustainable recovery of these compounds. For this purpose, novel liquid-liquid and solid-liquid extraction techniques have been studied, such as supercritical, ultrasound, microwave, enzymatic, high pressure, accelerated solvent and intensity pulsed electric fields extraction techniques. Moreover, different applications have been proposed for these compounds, such as preservatives in the food or cosmetic industries, as antibiotics in the pharmaceutical industry, as antibiofilm, antifouling, coating in active packaging, prebiotics or in nanoparticles. This review presents the main antimicrobial potential of macroalgae, their specific bioactive compounds and novel green extraction technologies to efficiently extract them, with emphasis on the antibacterial and antifungal data and their applications.

Exposure of rainbow trout (Oncorhynchus mykiss) to magnetite (Fe3O4) nanoparticles in simplified food chain: Study on ultrastructural characterization

The widespread exposure of metallic nanoparticles to the aquatic ecosystem and its adverse impact on human life is the colossal concern worldwide. In view of this, this context was investigated to analyze microscopically the bioaccumulation and localization of magnetite (Fe₃O₄) nanoparticles in the cellular organelles of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in aquatic conditions. Initially, Fe₃O₄ nanoparticles were absorbed on to Elodea (Elodea canadensis) and fed to molluscs (Melanopsis praemorsa). Fish were fed with the same molluscs, and then the intestines and liver were examined using light and transmission electron microscopy. Results showed that nanoparticles were present in the cytoplasm and other organelles of cells (mitochondrion and lysosome) by absorbing through microvilli of the epithelial cells of the tunica mucosa in the intestine. Further, nanoparticles passed through the vessels of the lamina propria of the tunica mucosa and reached to the sinusoids of the liver via blood circulation. It was then accumulated from the endothelium of the sinusoid to the cytoplasm of liver hepatocytes and to mitochondria and lysosome. The accumulation of nanoparticles in the epithelial cells, cytoplasm, mitochondria, and lysosome revealed the degree of transparency of the pattern with slight hesitation. In summary, this investigation contributed towards the understanding of the physiological effects of Fe₃O₄ nanoparticles on O. mykiss, which ascertains essentiality for sustainable development of nanobiotechnology in the aquatic ecosystem.

Magnetically guided targeted delivery of erythropoietin using magnetic nanoparticles: Proof of concept

The objective of this proof-of-concept study was to demonstrate the targeted delivery of erythropoietin (EPO) using magnetically guided magnetic nanoparticles (MNPs).MNPs consisting of a ferric-ferrous mixture (FeCl3·6H2O and FeCl2·4H2O) were prepared using a co-precipitation method. The drug delivery system (DDS) was manufactured via the spray-drying technique using a nanospray-dryer. The DDS comprised 7.5 mg sodium alginate, 150 mg MNPs, and 1000 IU EPO.Scanning electron microscopy revealed DDS particles no more than 500 nm in size. Tiny particles on the rough surfaces of the DDS particles were composed of MNPs and/or EPO, unlike the smooth surfaces of the only alginate particles. Transmission electron microscopy showed the tiny particles from 5 to 20 nm in diameter. Fourier-transform infrared spectroscopy revealed DDS peaks characteristic of MNPs as well as of alginate. Thermal gravimetric analysis presented that 50% of DDS weight was lost in a single step around 500°C. The mode size of the DDS particles was approximately 850 nm under in vivo conditions. Standard soft lithography was applied to DDS particles prepared with fluorescent beads using a microchannel fabricated to have one inlet and two outlets in a Y-shape. The fluorescent DDS particles reached only one outlet reservoir in the presence of a neodymium magnet. The neurotoxicity was evaluated by treating SH-SY5Y cells in 48-well plates (1 × 10 cells/well) with 2 μL of a solution containing sodium alginate (0.075 mg/mL), MNPs (1.5 mg/mL), or sodium alginate + MNPs. A cell viability assay kit was used to identify a 93% cell viability after MNP treatment and a 94% viability after sodium alginate + MNP treatment, compared with the control. As for the DDS particle neurotoxicity, a 95% cell viability was noticed after alginate-encapsulated MNPs treatment and a 93% cell viability after DDS treatment, compared with the control.The DDS-EPO construct developed here can be small under in vivo conditions enough to pass through the lung capillaries with showing the high coating efficiency. It can be guided using magnetic control without displaying significant neurotoxicity in the form of solution or particles.

Antibacterial and Antiviral Activities of Local Thai Green Macroalgae Crude Extracts in Pacific white Shrimp (Litopenaeus vannamei)

Macroalgae are potentially excellent sources of bioactive secondary metabolites useful for the development of new functional ingredients. This study was conducted to determine the antimicrobial efficacy of the hot water crude extracts (HWCEs) of three species of local Thai green macroalgae Ulva intestinalis (Ui), U. rigida (Ur), and Caulopa lentillifera (Cl) and a commercial ulvan from U. armoricana (Ua). Chemical analysis indicated that the HWCE of Ur showed the highest sulfate content (13.9% ± 0.4%), while that of Ua contained the highest uronic acid and carbohydrate contents (41.47% ± 4.98% and 64.03% ± 2.75%, respectively), which were higher than those of Ur (32.75% ± 1.53% and 51.02% ± 3.72%). Structural analysis of these extracts by Fourier-transform infrared (FTIR) spectroscopy revealed that these HWCEs are complex with a signal at 1250 cm-1 corresponding to S=O stretching vibrations, while the signals at 850 cm-1 were attributed to the C-O-S bending vibration of the sulfate ester in the axial position. These HWCEs showed the growth suppression against some pathogenic Vibrio spp. Interestingly, the HWCEs from Ui at concentrations of 5 and 10 mg/mL completely inhibited white spot syndrome virus (WSSV) in shrimp injected with HWCE-WSSV preincubated solutions. This inhibitory effect was further confirmed by the reduction in viral loads and histopathology of surviving and moribund shrimp.

Effects of iron oxide nanoparticles (Fe3O4) on life history and metabolism of the Neotropical cladoceran Ceriodaphnia silvestrii

Nanoparticles (NPs) production is increasing worldwide. These products are likely to end up in aquatic environments. However, few studies evaluated the chronic toxicity of iron-based NPs (Fe-NPs) to cladocerans and their potential ecotoxicological hazards. In this study we aimed to investigate the effects of iron oxide nanoparticles (Fe₃O₄-NPs) to Ceriodaphnia silvestrii Daday, 1902, assessing acute (48 h) and chronic toxicity (up to 14 d). Besides traditional endpoints (immobility and lethality), we also evaluated physiological responses (respiration rates) in a 48 h-exposure. No immobility was observed (EC₅₀ > 100 mg L^-1) after 48 h, whereas respiration rates at the highest concentration were 400% of that in control, indicating that this endpoint was more sensitive during acute toxicity. In chronic assays, Fe₃O₄-NPs affected body length (8.24% growth inhibition in 7 d-exposure) and number of eggs (7-d IC₁₀: 3.53, IC₂₀: 6.69 mg Fe L^-1) and neonates (7-d IC₁₀: 1.25, IC₂₀: 3.75 mg Fe L^-1). Based on species sensitivity distribution (SSD), C. silvestrii was a sensitive organism, suggesting Fe-NPs as a possible threat for this species. Our results also indicate that the NPs caused a physical barrier, impairing food absorption, since we observed NPs agglomerations into cladocerans' gut. We demonstrate that Fe₃O₄-NPs affects C. silvestrii metabolism and reproduction and our results support the use of sublethal endpoints to assess environmental safety. The release of these NPs into freshwater environments should be carefully evaluated, since disturbances on cladoceran population dynamics could cause strong impacts on the entire food web structure and ultimately on ecosystem functioning.

Recent advances in the biotoxicity of metal oxide nanoparticles: Impacts on plants, animals and microorganisms

The contact between metal oxide nanoparticles (NPs) and human is more and more close with their wide applications. The inputs of metal oxide NPs to the environment are also growing every year, which causes potential environmental and human health risks. They are toxic to animals, microorganisms and plants at high concentrations, and they show different mechanisms of toxicity to different species. In addition, under complex environmental conditions, their toxic effects are often unpredictable. We have integrated the recent studies on the biotoxicity of metal oxide NPs from 2015-present, and clarified their toxic mechanism, as well as the toxic harm. It lays a foundation for further studying the toxicity and ecological risk of metal oxide NPs.

Effects of fulvic acid on aggregation, sedimentation, and adsorption of Fe3O4 magnetic nanoparticles

Environmental behavior, bioavailability, and risks posed by Fe₃O₄, magnetic nanoparticles (Fe₃O₄ NPs) in surface waters are affected by complex geochemistry, including pH and inorganic and organic matter. This work provides a systematic analysis of adsorption of fulvic acid (FA) on surfaces of Fe₃O₄ NPs with adsorption kinetics, adsorption thermodynamic, and adsorption isotherm. Adsorption of FA on surfaces of Fe₃O₄ NPs is consistent with assumptions of Langmuir and Freundlich adsorption isotherm models. The adsorption amount of FA was inversely proportional to solution pH, and the maximum amount is 128.6 mg g^-1. Adsorption of FA on surfaces of Fe₃O₄ NPs is a spontaneous endothermic process. FA plays an important role in aggregation and suspension/sedimentation behavior of Fe₃O₄ NPs in aquatic environmental. With continuous adsorption of FA, electrostatic repulsion between the particles and the steric hindrance of FA significantly decreased aggregation and increased suspension of Fe₃O₄ NPs. The results of FTIR and XPS indicated that FA was adsorbed on Fe₃O₄ NPs mainly through chemical reactions, and carbohydrates particularly play an important role in adsorption.

Dissolved Organic Matter Modulates Algal Oxidative Stress and Membrane System Responses to Binary Mixtures of Nano-Metal-Oxides (nCeO2, nMgO and nFe3O4) and Sulfadiazine

Joint biomarker responses, oxidative stress and membrane systems, were determined for nano-metal-oxides (nMeO, i.e., nCeO₂, nMgO, and nFe₃O₄) and sulfadiazine (SDZ) exposed at relevant low concentrations to two freshwater microalgae Scenedesmus obliquus and Chlorella pyrenoidosa. The impacts of dissolved organic matter (DOM) on the joint biomarker responses were also investigated. Results indicated that the presence of SDZ significantly decreased the level of intercellular reactive oxygen species (ROS) in the algal cells exposed to each nMeO. Reduction of cell membrane permeability (CMP) and mitochondrial membrane potential (MMP) in the algal cells was observed when the algae were exposed to the mixture of SDZ and the nMeO. The degree of reduction of the ROS level, CMP, and MMP significantly went down with the addition of DOM to a certain extent. Changes in cellular oxidative stress and membrane function depended on the types of both nMeO and algal species. This contribution provides an insight into the hazard assessment of a mixture consisting of emerging contaminants and DOM, as they can coexist in the aquatic environment.

High concentration of Phaeocystis globosa reduces the sensitivity of rotifer Brachionus plicatilis to cadmium: Based on an exponential approach fitting the changes in some key life-history traits

Most coastal waters are at risk of heavy metal pollution, and the biomass of primary producer phytoplankton always fluctuates, which usually causes zooplankton to be exposed in different concentrations of food and heavy metal. Phytoplankton abundance and heavy metal may interact on zooplankton. Therefore, to assess the definite interactive way, in this study we investigated the combined effects of different cadmium (Cd) levels and Phaeocystis globosa concentrations on some key life-history traits of the rotifer Brachionus plicatilis. Results showed that the Cd level and P. globosa concentration had a significant interaction on the key life-history parameters of the rotifer. Mid-level algal concentrations (5-36 × 10⁴ cells mL^-1) had an apparent effect on brood production and the number of rotifers producing offspring at high Cd level. The time to first reproduction exponentially decreased with increasing P. globosa concentrations under any Cd levels and then subsequently reached a constant value. With increasing P. globosa concentration, the total number of offspring exponentially increased and then reached the asymptotic value; the survival time under any Cd levels exponentially decreased with the increasing P. globosa concentration and subsequently tended to be a constant value. Without Cd, the low P. globosa concentration only decreased the reproduction of rotifers. However, the extreme low P. globosa concentration (1-3 × 10⁴ cells mL^-1) under higher Cd level (0.0354 mM) completely inhibited the reproduction and also shorten the survival time. Higher Cd level decreased the asymptotic total offspring per rotifer and survival time. High concentration of P. globosa can reduce the sensitivity of rotifer to heavy metal. However, the negative effects could not be eliminated completely by the increasing P. globosa concentration. The findings indicated that ecotoxicological studies on the toxicity of heavy metal need to consider the effects of food concentrations, which contributes to understanding the diverse tolerance of zooplankton to heavy metals.

The Toxicity Assessment of Iron Oxide (Fe₃O₄) Nanoparticles on Physical and Biochemical Quality of Rainbow Trout Spermatozoon

The aim of this study was to evaluate the in vitro effect of different doses (50, 100, 200, 400, and 800 mg/L) of Fe₃O₄ nanoparticles (NPs) at 4 °C for 24 h on the kinematics of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) spermatozoon. Firstly, Fe₃O₄ NPs were prepared at about 30 nm from Iron (III) chloride, Iron (II) chloride, and NH₃ via a co-precipitation synthesis technique. Then, the prepared Fe₃O₄ NPs were characterized by different instrumental techniques for their chemical structure, purity, morphology, surface properties, and thermal behavior. The size, microstructure, and morphology of the prepared Fe₃O₄ NPs were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) spectroscopy, and scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS). The thermal properties of the Fe₃O₄ NPs were determined with thermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimeter (DSC) analysis techniques. According to our results, there were statistically significant (p < 0.05) decreases in the velocities of spermatozoon after treatment with 400 mg/L Fe₃O₄ NPs. The superoxide dismutase (SOD) and catalase (CAT) activities were significant (p < 0.05) decrease after 100 mg/L in after exposure to Fe₃O₄ NPs in 24 h. As the doses of Fe₃O₄ NPs increases, the level of malondialdehyde (MDA) and total glutathione (tGSH) significantly (p < 0.05) increased at doses of 400 and 800 mg/L.