Toxicity of TiO2, SiO2, ZnO, CuO, Au and Ag engineered nanoparticles on hatching and early nauplii of Artemia sp

Zirconium and cerium dioxide fabricated activated carbon-based nanocomposites for enhanced adsorption and photocatalytic removal of methylene blue and tetracycline hydrochloride

Activated carbon (AC) is a porous, amorphous form of carbon known for its strong adsorption capacity, making it highly effective for use in wastewater treatment. In this investigation, AC-based nanocomposites (NCs) loaded with zirconium dioxide and cerium dioxide nanoparticles (ZrO2/CeO2 NPs) were successfully synthesized for the effective elimination of methylene blue (MB) and tetracycline hydrochloride (TCH). The AC-ZrO2/CeO2 NCs have a size of 231.83 nm, a zeta potential of -20.07 mV, and a PDI value of 0.160. The adsorption capacities of AC-ZrO2/CeO2 NCs for MB and TCH were proved in agreement with the Langmuir isotherm and pseudo 1st order kinetic model, respectively. The maximum adsorption capacities were determined to be 75.54 mg/g for MB and 26.75 mg/g for TCH. Notably, AC-ZrO2/CeO2 NCs exhibited superior photocatalytic degradation efficiency for MB and TCH under sunlight irradiation with removal efficiencies reaching up to 97.91% and 82.40% within 90 min, respectively. The t1/2 for the photo-degradation process of MB and TCH were 11.55 min and 44.37 min. Analysis of active species trapping confirmed the involvement of hole (h+), superoxide anion (•O2-), and hydroxyl radical (•OH) in the degradation mechanism. Furthermore, the residual solution post-contaminant removal exhibited minimal toxicity towards Artemia salina and NIH3T3 cells. Importantly, the NCs did not exhibit antibacterial activity against tested pathogens post-absorption/degradation of TCH. Thus, AC-ZrO2/CeO2 NCs could be a promising nanomaterial for wastewater treatment applications.

Assessing toxicity mechanism of silver nanoparticles by using brine shrimp (Artemia salina) as model

The acute toxicity of silver nanoparticles (AgNPs) in Artemia salina is primarily attributed to the interaction between silver ions (Ag+) and chitin, which constitutes the main structural component of the organism's cuticle. To investigate this interaction and gain a deeper understanding of its nature, geometric optimization calculations and symmetry-adapted perturbation theory (SAPT0) analysis were performed. These calculations aimed to determine the most favorable conformation based on the binding energies of silver ions with chitin and to elucidate the underlying mechanisms of their interaction. The results indicate an ionic effect dependent on the ion state, with simulations revealing that Ag3+ ions have the potential to cause significant deformation of the chitin structure. Furthermore, this study evaluated the behavior of AgNPs using nauplii of A. salina instar I, assessing both mortality rates and cell damage. Toxicity of AgNPs was observed in A. salina at concentrations of 50 and 100 ppm within a timeframe of 24-48 h. The toxicity of AgNPs can be attributed to their interaction with the cuticle and subsequent modification of the chitin structure through the binding of ionic silver. Light microscopy (LM) analysis confirmed the presence of AgNPs in the cuticle, while confocal laser scanning microscopy (CLSM) revealed cellular damage. In addition, this research offers new perspectives on the toxicity mechanism of AgNPs by introducing a novel model that explores the interaction of silver ions with the cuticle of A. salina. These insights are derived from a combination of atomistic models and ecotoxicology assays.

Seawater quality criteria and ecotoxicity risk assessment of zinc oxide nanoparticles based on data of resident marine organisms in China

Water quality criteria (WQC) for zinc oxide nanoparticles (ZnO NPs) are crucial due to their extensive industrial use and potential threats to marine organisms. This study conducted toxicity tests using marine organisms in China, revealing LC50 or EC50 values for ZnO NPs ranging from 0.36 to 95.6 mg/L across seven species, among which the salinity lake crustacean zooplankton Artemia salina exhibited the highest resistance, while diatom Phaeodactylum tricornutum the most sensitive. Additionally, the EC10 or maximum acceptable toxicant concentration (MATC) values for ZnO NPs were determined for five species, ranging from 0.03 to 2.82 mg/L; medaka Oryzias melastigma demonstrated the highest tolerance, while mysis shrimp Neomysis awatschensis the most sensitive. Based on the species sensitivity distribution (SSD) method, the derived short-term and long-term WQC for ZnO NPs were 138 μg/L and 8.37 μg/L, respectively. These values were further validated using the sensitive species green algae Chlorella vulgaris, confirming effective protection. There is no environmental risk observed in Jiaozhou Bay, Yellow River Estuary and Laizhou Bay in the northern coastal seas of China. This study provides important reference data for the establishment of water quality standards for nanoparticles.

Mechanistic study of copper oxide, zinc oxide, cadmium oxide, and silver nanoparticles-mediated toxicity on the probiotic Lactobacillus reuteri

The use of metal/metal oxide nanoparticles (NPs) in consumer products has increased dramatically. Accordingly, human exposure to these NPs has increased. Lactobacillus reuteri, a member of the beneficial gut microbiota, is essential for human health. In the present study, the toxic effect of three metal oxides (CuO, ZnO, and CdO) and one metal (Ag) NPs on L. reuteri were investigated in vitro. L. reuteri was susceptible to all the prepared NPs in a dose-dependent manner, visualized as an increase in the zones of inhibition and a significant reduction in the maximum specific growth rates (µmax). The minimal inhibitory concentrations were 5.8, 26, 560, and 560 µg/mL for CdO-, Ag-, ZnO-, and CuO-NPs, respectively, and the respective minimal bactericidal concentrations were 60, 70, 1500, and 1500 µg/mL. Electron microscopic examinations revealed the adsorption of the prepared NPs on L. reuteri cell surface, causing cell wall disruption and morphological changes. These changes were accompanied by significant leakage of cellular protein content by 214%, 191%, 112%, and 101% versus the untreated control when L. reuteri was treated with CdO-, Ag-, CuO-, and ZnO-NPs, respectively. NPs also induced oxidative damage, where the malondialdehyde level was significantly increased, and glutathione content was significantly decreased. Quantifying the DNA damage using comet assay showed that CuONPs had the maximum DNA tail length (8.2 px vs. 2.1 px for the control). While CdONPs showed the maximum percentage of DNA in tail (15.5% vs. 3.1%). This study provides a mechanistic evaluation of the NPs-mediated toxicity to a beneficial microorganism.

Sublethal Effects of Polystyrene Nanoplastics on the Embryonic Development of Artemia salina (Linnaeus, 1758)

Currents, wave motion, solar radiation, and abrasion are mechanisms responsible for the degradation of large plastic artifacts and contribute to the dispersion of micro and nanoplastics into aquatic ecosystems, which are, currently, the most dangerous threats due to their invisibility and persistence. The present work evaluated the possible lethal and sublethal effects of amino-modified polystyrene nanoplastics (nPS-NH2) with diameters of 50 nm and 100 nm on Artemia salina (A. salina), an organism at the base of the trophic chain of the aquatic system, using a widely used model for the analysis of embryotoxicity from environmental pollutants. For this purpose, after evaluating the biodistribution of nanoplastics in the body of the tested animals, several endpoints such as anomalies, apoptosis, and ROS production were assessed. In addition, particular attention was dedicated to evaluating the correlation between toxicity and the particle size tested. The results reported that, despite the absence of a lethal impact, several sublethal effects involving gut and body size malformations, as well as the enhancement of apoptosis and oxidative stress in relation to an increase in tested concentration and a decrease in nanoparticle size.

Evaluation of antibacterial activity, in-vitro cytotoxicity and catalytic activity of biologically synthesized silver nanoparticles using leaf extracts of Leea macrophylla

Nanotechnology has become a cutting-edge field of research that has emerged as an interdisciplinary research area and contributes to almost every field of science. With the increasing demand for sustainable greener products, attention has recently been focused on green nanotechnology. This study manifested the aptitude of Leea macrophylla (LM) leaf extract, fortified with phytochemicals, to biosynthesize silver nanoparticles (AgNPs) for the first time. As soon as the AgNPs were biosynthesized, they immediately changed color, and the distinctive surface plasmon resonance (SPR) occurred at 420 nm in the Ultraviolet-Visible spectrum, proving that the biosynthesis had been successful. Fourier Transform Infrared Spectroscopy (FTIR) was used to examine the phytochemicals present in the LM leaf extract, those are accountable for the formation and stabilization of AgNPs. The Transmission Electron Microscope (TEM) revealed the formation of quasi spherical silver nanoparticles with an average diameter of 22.77 nm. Synthesized nanoparticles were further characterized by X-ray diffraction (XRD), Field Emission Scanning Electron microscope (FESEM), Energy Dispersive X-ray (EDX), Dynamic Light Scattering (DLS) and Thermogravimetric analysis (TGA). The production of AgNPs with high metal content from LM leaf extract exhibited encouraging results. The LM leaf extract mediated silver nanoparticles evinced significant antibacterial and catalytic activities. The cytotoxicity effects of biosynthesized AgNPs were tested on brine shrimps.

Individual and binary exposure to nanoscales of silver, titanium dioxide, and silicon dioxide alters viability, growth, and reproductive system: Hidden indices to re-establish artemia as a toxicological model in saline waters

This study evaluated and compared the individual and combined toxicity of AgNPs, TiO₂NPs, and SiO₂NPs to life cycle of A. salina. To this end, both stability and toxicity of AgNPs were determined in the presence of TiO₂NPs and SiO₂NPs. The colloidal stability of AgNPs decreased in the presence of the other two NPs, especially SiO₂NPs. AgNPs displayed acute toxicity to A. salina, whereas SiO₂NPs and TiO₂NPs chronically induced toxicity in a concentration- and time-dependent manner during 28-day exposure. The experimental NPs significantly decreased the weight and length of A. salina and induced reproductive toxicity through perturbation in first brood timespan, sexual maturity, egg development time, egg pouch area, offspring quality, and fecundity. Exposure to AgNPs shifted the mode of reproduction in brine shrimp from ovoviviparity to oviparity, and also co-presence of AgNPs with SiO₂NPs or TiO₂NPs caused infertility. Generally, their individual toxicity was in order of AgNPs > TiO₂NPs > SiO₂NPs, and binary exposure to AgNPs-SiO₂NPs appear to be more threatening than AgNPs-TiO₂NPs to A. salina. Together, this study highlights that these nanoparticles could disrupt reproductive health of A. salina and lead to alterations in population dynamics and aquatic ecosystem balance.

Silver nanoparticle toxicity on Artemia parthenogenetica nauplii hatched on axenic tryptic soy agar solid medium

The use of gnobiotic brine shrimp (Artemia spp.) for ecotoxicology and bacteria-host interaction studies is common. However, requirements for axenic culture and matrix effects of seawater media can be an obstacle. Thus, we investigated the hatching ability of Artemia cysts on a novel sterile Tryptic Soy Agar (TSA) medium. Herein, we demonstrate for the first time that Artemia cysts can hatch on a solid medium without liquid, which offers practical advantages. We further optimized the culture conditions for temperature and salinity and assessed this culture system for toxicity screening of silver nanoparticles (AgNPs) across multiple biological endpoints. Results revealed that maxima hatching (90%) of embryos occurred at 28 °C and without addition of sodium chloride. When capsulated cysts were cultured on TSA solid medium Artemia were negatively impacted by AgNPs at 30-50 mgL^-1 in terms of the embryo hatching ratio (47-51%), umbrella- to nauplii-stage transformation ratio (54-57%), and a reduction in nauplii-stage growth (60-85% of normal body length). At 50-100 mgL^-1 AgNPs and higher, evidence of damage to lysosomal storage was recorded. At 500 mgL^-1 AgNPs, development of the eye was inhibited and locomotory behavior impeded. Our study reveals that this new hatching method has applications in ecotoxicology studies and provides an efficient means to control axenic requirements to produce gnotobiotic brine shrimp.

Isolation and characterization of microplastics from skin care products; interactions with albumin proteins and in-vivo toxicity studies on Artemia salina

Skincare products are a significant source of primary microplastics (MPs). This study isolates and characterizes microplastic from two skin care products: face wash (FW-MPs) and face scrub (FS-MPs). Microplastics extracted were around 660 µm in size. The extracted MPs, designated as unground MPs (UG-MPs), were smooth surface and spherical. Ground ones were denoted as the ground MPs (G-MPs) that varied in size and surface shape. G-MPs interacted with bovine serum albumin (BSA) and human serum albumin (HSA). BSA adsorption on FW-MPs was 29%, whereas HSA adsorption was 47%. Contrarily, FS-MPs displayed 17% and 31%. Fluorescence spectroscopy and FE-SEM images showed HSA adsorption on G-MPs was greater than BSA. G-MP interaction changed the life cycle of Artemia salina. UV-Vis and fluorescence spectroscopy were used to study protein adsorption and desorption on G-MPs. A. salina treated to 2.5 mg/mL G-MPs delayed hatching and development and internalized microplastics in the gut at 144 h exposure.

Effects of Photodynamic Therapy on Streptococcus mutans and Enamel Remineralization of Multifunctional TiO2-HAP Composite Nanomaterials

BACKGROUND

As photosensitizer and photocatalyst, titanium dioxide (TiO₂) can produce a photodynamic reaction for antibacterial treatment. This study aims to explore a Titanium dioxide/nano-hydroxyapatite (TiO₂-HAP) composite combined with the dental curing lamp (385-515 nm) in clinical which could inhibit the dental plaque biofilm formed by Streptococcus mutans (S. mutans) and promote the enamel surface remineralization simultaneously.

METHODS

X-ray Diffraction (XRD) and high resolution transmission electron microscope (HRTEM) were used to detect the characterization of TiO₂-HAP composite nanomaterials. Photodynamic properties of TiO₂-HAP were detected by Diffuse reflectance spectrum (DRS) and fluorescence spectroscopy. Bacterial growth was measured by reading the absorbance of bacterial cultures and confocal microscope was used to observe the biofilm removal ability of nanomaterials. The ability of TiO₂-HAP to promote enamel remineralization was measured by Scanning electron microscope (SEM).

RESULTS

The OD 600 of S. mutans was 0.76 in the control group and 0.13 in group of TiO₂-HAP with exposure to light-emitting diode (LED) (150 mW/cm²) for 5 min, suggesting its sustained antibacterial potency and inhibition of the metabolic activity of dental plaque microcosm biofilm. Also, the release of calcium and phosphorus ions in TiO₂-HAP can promote enamel mineralization simultaneously. After 15 days of remineralization, the Ca/P ratio of demineralized enamel surface increased from 1.28 to 1.67, which was similar to that of normal enamel.

CONCLUSIONS

The TiO₂-HAP exhibit a promising anti-bacterial activity and remineralization capacity which can prevent the occurrence of caries to the greatest extent and promote the biomimetic mineralization of dental tissues.

A comprehensive estimate of the aggregation and transport of nSiO2 in static and dynamic aqueous systems

Silicon dioxide nanoparticles (nSiO₂) are extensively used in diverse fields and are inevitably released into the natural environment. Their overall aggregation behaviour in the environmental matrix can determine their fate and ecotoxicological effect on terrestrial and aquatic life. The current study systematically evaluates multiple parameters that can influence the stability of colloidal nSiO₂ (47 nm) in the natural aquatic environment. At first, the influence of several hydrochemical parameters such as pH (5, 7, and 9), ionic strength (IS) (10, 50, and 100 mM), and humic acid (HA) (0.1, 1, and 10 mg L^-1) was examined to understand the overall aggregation process of nSiO₂. Furthermore, the synergistic and antagonistic effects of ionic strength and humic acid on the transport of nSiO₂ in the aqueous environment were examined. Our experimental findings indicate that pH, ionic strength, and humic acid all had a profound influence on the sedimentation process of nSiO₂. The experimental observations were corroborated by calculating the DLVO interaction energy profile, which was shown to be congruent with the transport patterns. The present study also highlights the influence of high and low shear forces on the sedimentation process of nSiO₂ in the aqueous medium. The presence of shear force altered the collision efficiency and other interactive forces between the nanoparticles in the colloidal suspension. Under the experimental stirring conditions, a higher abundance of dispersed nSiO₂ in the upper layer of the aqueous medium was noted. Additionally, the transport behaviour of nSiO₂ was studied in a variety of natural water systems, including rivers, lakes, ground, and tap water. The study significantly contributes to our understanding of the different physical, chemical, and environmental aspects that can critically impact the sedimentation and spatial distribution of nSiO₂ in static and dynamic aquatic ecosystems.

Mixture toxicity of TiO2 NPs and tetracycline at two trophic levels in the marine ecosystem: Chlorella sp. and Artemia salina

Increasing usage of both nanomaterials and pharmaceuticals and their unabated release to the marine ecosystem pose a serious concern nowadays. The toxicity of the mixture of TiO₂ NPs and tetracycline (TC) in the marine species are not very well covered in prior literature. The current study explores the joint toxic effects of TiO₂ NPs and TC in a simulated marine food chain: Chlorella sp. and Artemia salina. Chlorella sp. was interacted with pristine TiO₂ NPs (0.05, 05, and 5 mg/L), TC (0.5 mg/L), and their combinations for 48 h. The toxicity induced in Chlorella sp. by pristine TiO₂ NPs through oxidative stress and chloroplast damage was not significantly changed in the presence of TC. Principal component analysis for the toxicity parameters revealed a strong association between growth inhibition and adsorption/internalization. In the second trophic level (A. salina), the waterborne exposure of TC additively increased the toxicity of TiO₂ NPs. Both adsorption and degradation played a major role in the removal of TC from the suspension, resulting in additive toxic effects in both Chlorella sp. and A. salina. Compared to the waterborne exposure, the foodborne exposure of TiO₂ NPs and TC induced lesser toxic effects owing to reduced uptake and accumulation in A. salina. Biomagnification results indicate that the dietary transfer of TiO₂ NPs and TC does not pose a serious environmental threat in this two-level marine food chain.

Too small to matter? Physicochemical transformation and toxicity of engineered nTiO2, nSiO2, nZnO, carbon nanotubes, and nAg

Engineered nanomaterials (ENMs) refer to a relatively novel class of materials that are increasingly prevalent in various consumer products and industrial applications - most notably for their superlative physicochemical properties when compared with conventional materials. However, consumer products inevitably degrade over the course of their lifetime, releasing ENMs into the environment. These ENMs undergo physicochemical transformations and subsequently accumulate in the environment, possibly leading to various toxic effects. As a result, a significant number of studies have focused on identifying the possible transformations and environmental risks of ENMs, with the objective of ensuring a safe and responsible application of ENMs in consumer products. This review aims to consolidate the results from previous studies related to each stage of the pathway of ENMs from being embodied in a product to disintegration/transformation in the environment. The scope of this work was defined to include the five most prevalent ENMs based on recent projected production market data, namely: nTiO₂, nSiO₂, nZnO, carbon nanotubes, and nAg. The review focuses on: (i) models developed to estimate environmental concentrations of ENMs; (ii) the possible physicochemical transformations; (iii) cytotoxicity and genotoxicity effects specific to each ENM selected; and (iv) a discussion to identify potential gaps in the studies conducted and recommend areas where further investigation is warranted.

Toxicity of Different Zinc Oxide Nanomaterials at 3 Trophic Levels: Implications for Development of Low-Toxicity Antifouling Agents

Because zinc oxide (ZnO) nanomaterials are used in antifouling and antibacterial solutions, understanding their toxic effects on different aquatic organisms is essential. In the present study, we evaluated the toxicity of ZnO nanoparticles of 10 to 30 nm (ZnONPI) and 80 to 200 nm (ZnONPII), ZnO nanorods (width 80 nm, height 1.7 µm) attached to the support substrate (glass, ZnONRG) and not attached (ZnONRS), as well as Zn²⁺ ions at concentrations ranging from 0.5 to 100 mg/L. Toxicity was evaluated using the microalga Dunaliella salina, the brine shrimp Artemia salina, and the marine bacterium Bacillus cereus. The highest toxicity was observed for ZnONPs (median lethal concentration [LC50] ~15 mg/L) and Zn²⁺ ions (LC50 ~13 mg/L), whereas the lowest toxicity found for ZnO nanorods (ZnONRG LC50 ~60 mg/L; ZnONRS LC50 ~42 mg/L). The presence of the support substrate in case of ZnO nanorods reduced the associated toxicity to aquatic organisms. Smaller ZnONPs resulted in the highest Zn²⁺ ion dissolution among tested nanostructures. Different aquatic organisms responded differently to ZnO nanomaterials, with D. salina and B. cereus being more sensitive than A. salina. Toxicity of nanostructures increased with an increase of the dose and the time of exposure. Supported ZnO nanorods can be used as a low-toxicity alternative for future antimicrobial and antifouling applications. Environ Toxicol Chem 2020;39:1343-1354. © 2020 SETAC.

The effective adsorbent capacity of rice husk to iron and aluminum oxides nanoparticles using Oreochromis niloticus as a bioindicator: biochemical and oxidative stress biomarkers

Metal oxide nanoparticles (NPs) have different industrial applications so it is unavoidable that NPs products could find their way into aquatic habitats. Therefore, toxic NPs must be treated sufficiently to reach the standard values before their discharge into the aquatic ecosystems. Our study aimed to investigate the adsorptive capacity of rice husk to iron and aluminum oxides from water and reducing their potential toxic effects. Fish were classified into eight groups for 7 days: Fe₂O₃ NPs (10 mg/l)-exposed group; Al₂O₃ NPs (10 mg/l)-exposed group; combined group (same concentrations of Fe₂O₃ and Al₂O₃NPs), and control group (dechlorinated water). The other four groups were the same as the above groups but with 50 mg/l rice husk in each group. Compared with control groups, our results showed a significant (p < 0.05) increase in plasma total proteins, globulin, glucose, liver enzymes, and kidney function biomarkers (creatinine and uric acid). While the recorded albumin and total lipids were significantly decreased. The oxidative biomarkers in liver and gill tissues of NPs-exposed fish showed significant (p < 0.05) reduction in glutathione-reduced content and elevation in thiobarbituric acid reactive substances, glutathione peroxidase, catalase, and superoxide dismutase. Based on our results, Fe₂O₃ NPs were more toxic than Al₂O₃ NPs. The combined doses of both NPs showed more or less toxicity compared to single doses. Therefore, this point needs more studies to show the mode of interaction. Finally, rice husk was a good adsorber to both NPs as it could improve the biochemical and antioxidant status of the studied fish.

Effect of TiO2-ZnO-MgO Mixed Oxide on Microbial Growth and Toxicity against Artemia salina

Mixed oxide nanoparticles (MONs, TiO₂–ZnO–MgO) obtained by the sol-gel method were characterized by transmission electron microscopy, (TEM, HRTEM, and SAED) and thermogravimetric analysis (TGA/DTGA–DTA). Furthermore, the effect of MONs on microbial growth (growth profiling curve, lethal and sublethal effect) of Escherichia coli, Salmonella paratyphi, Staphylococcus aureus and Listeria monocytogenes, as well as the toxicity against Artemia salina by the lethal concentration test (LC₅₀) were evaluated. MONs exhibited a near-spherical in shape, polycrystalline structure and mean sizes from 17 to 23 nm. The thermal analysis revealed that the anatase phase of MONs is completed around 480–500 °C. The normal growth of all bacteria tested is affected by the MONs presence compared with the control group. MONs also exhibited a reduction on the plate count from 0.58 to 2.10 log CFU/mL with a sublethal cell injury from 17 to 98%. No significant toxicity within 24 h was observed on A. salina. A bacteriostatic effect of MONs on bacteria was evidenced, which was strongly influenced by the type of bacteria, as well as no toxic effects (LC₅₀ >1000 mg/L; TiO₂–ZnO (5%)–MgO (5%)) on A. salina were detected. This study demonstrates the potential of MONs for industrial applications.

The Influence of Talc Addition on the Performance of Polypropylene Membranes Formed by TIPS Method

The effect of talc addition on the morphology of capillary membranes formed by a thermally induced phase separation (TIPS) method was investigated in the presented work. The usability of such formed membranes for membrane distillation was evaluated. Two types of commercial capillary polypropylene membranes, fabricated for microfiltration process, were applied in the studies. A linear arrangement of polymer chains was obtained in the walls of membranes formed without a talc addition. In the case of membranes blended with talc, the linear structure was disordered, and a more porous structure was obtained. The changes in morphology enhanced the mechanical properties of blended membranes, and their lower thermal degradation was observed during 350 h of membrane distillation studies. Long-term studies confirmed the stability of talc dispersion in the membrane matrix. A leaching of talc from polypropylene (PP) membranes was not found during the membrane distillation (MD) process.