Nanoparticles: An Experimental Study of Zinc Nanoparticles Toxicity on Marine Crustaceans. General Overview on the Health Implications in Humans

Ultraviolet Filters: Dissecting Current Facts and Myths

Skin cancer is a global and increasingly prevalent issue, causing significant individual and economic damage. UV filters in sunscreens play a major role in mitigating the risks that solar ultraviolet ra-diation poses to the human organism. While empirically effective, multiple adverse effects of these compounds are discussed in the media and in scientific research. UV filters are blamed for the dis-ruption of endocrine processes and vitamin D synthesis, damaging effects on the environment, induction of acne and neurotoxic and carcinogenic effects. Some of these allegations are based on scientific facts while others are simply arbitrary. This is especially dangerous considering the risks of exposing unprotected skin to the sun. In summary, UV filters approved by the respective governing bodies are safe for human use and their proven skin cancer-preventing properties make them in-dispensable for sensible sun protection habits. Nonetheless, compounds like octocrylene and ben-zophenone-3 that are linked to the harming of marine ecosystems could be omitted from skin care regimens in favor of the myriad of non-toxic UV filters.

Adjuvant Novel Nanocarrier-Based Targeted Therapy for Lung Cancer

Lung cancer has the lowest survival rate due to its late-stage diagnosis, poor prognosis, and intra-tumoral heterogeneity. These factors decrease the effectiveness of treatment. They release chemokines and cytokines from the tumor microenvironment (TME). To improve the effectiveness of treatment, researchers emphasize personalized adjuvant therapies along with conventional ones. Targeted chemotherapeutic drug delivery systems and specific pathway-blocking agents using nanocarriers are a few of them. This study explored the nanocarrier roles and strategies to improve the treatment profile's effectiveness by striving for TME. A biofunctionalized nanocarrier stimulates biosystem interaction, cellular uptake, immune system escape, and vascular changes for penetration into the TME. Inorganic metal compounds scavenge reactive oxygen species (ROS) through their photothermal effect. Stroma, hypoxia, pH, and immunity-modulating agents conjugated or modified nanocarriers co-administered with pathway-blocking or condition-modulating agents can regulate extracellular matrix (ECM), Cancer-associated fibroblasts (CAF),Tyro3, Axl, and Mertk receptors (TAM) regulation, regulatory T-cell (Treg) inhibition, and myeloid-derived suppressor cells (MDSC) inhibition. Again, biomimetic conjugation or the surface modification of nanocarriers using ligands can enhance active targeting efficacy by bypassing the TME. A carrier system with biofunctionalized inorganic metal compounds and organic compound complex-loaded drugs is convenient for NSCLC-targeted therapy.

From lab to ecosystem: Understanding the ecological footprints of engineered nanoparticles

Nanotechnology has attained significant attention from researchers in past decades due to its numerous advantages, such as biocompatibility, biodegradability, and improved stability over conventional drug delivery systems. The fabrication of engineered nanoparticles (ENPs), including carbon nanotubes (CNTs), fullerenes, metallic and metal oxide-based NPs, has been steadily increasing day due to their wide range of applications from household to industrial applications. Fabricated ENPs can release different materials into the environment during their fabrication process. The effect of such materials on the environment is the primary concern with due diligence on the safety and efficacy of prepared NPs. In addition, an understanding of chemistry, reactivity, fabrication process, and viable mechanism of NPs involved in the interaction with the environment is very important. To date, only a limited number of techniques are available to assess ENPs in the natural environment which makes it difficult to ascertain the impact of ENPs in natural settings. This review extensively examines the environmental effects of ENPs and briefly discusses useful tools for determining NP size, surface charge, surface area, and external appearance. In conclusion, the review highlights the potential risks associated with ENPs and suggests possible solutions.

3D Airway Epithelial-Fibroblast Biomimetic Microfluidic Platform to Unravel Engineered Nanoparticle-Induced Acute Stress Responses as Exposome Determinants

Insights into how biological systems respond to high- and low-dose acute environmental stressors are a fundamental aspect of exposome research. However, studying the impact of low-level environmental exposure in conventional in vitro settings is challenging. This study employed a three-dimensional (3D) biomimetic microfluidic lung-on-chip (μLOC) platform and RNA-sequencing to examine the effects of two model anthropogenic engineered nanoparticles (NPs): zinc oxide nanoparticles (Nano-ZnO) and copier center nanoparticles (Nano-CCP). The airway epithelium exposed to these NPs exhibited dose-dependent increases in cytotoxicity and barrier dysregulation (dominance of the external exposome). Interestingly, even nontoxic and low-level exposure (10 μg/mL) of the epithelium compartment to Nano-ZnO triggered chemotaxis of lung fibroblasts toward the epithelium. An increase in α smooth muscle actin (α-SMA) expression and contractile activity was also observed in these cells, indicating a bystander-like adaptive response (dominance of internal exposome). Further bioinformatics and network analysis showed that a low-dose Nano-ZnO significantly induced a robust transcriptomic response and upregulated several hub genes associated with the development of lung fibrosis. We propose that Nano-ZnO, even at a no observable effect level (NOEL) dose according to conventional standards, can function as a potent nanostressor to disrupt airway epithelium homeostasis. This leads to a cascade of profibrotic events in a cross-tissue compartment fashion. Our findings offer new insights into the early acute events of respiratory harm associated with environmental NPs exposure, paving the way for better exposomic understanding of this emerging class of anthropogenic nanopollutants.

Hemocompatibility of dextran-graft-polyacrylamide/zinc oxide nanosystems: hemolysis or eryptosis?

Aim. In this study, blood compatibility of ZnO nanoparticles-polymer nanocomplex (D-PAA/ZnONPs(SO42-)) synthesizedin situinto dextran-graft-polyacrylamide (D-PAA) using zinc sulphate as a precursor was tested using hemolysis, osmotic fragility and eryptosis assays.Materials and methods. Dose-dependent ability to induce eryptosis was assessed following 24 h incubation at concentrations of 0-800 mg l-1analyzing hallmarks of eryptosis (cell shrinkage and phosphatidylserine externalization), as well as reactive oxygen species generation. Hemolysis was detected spectrophotometrically based on hemoglobin release following exposure to the D-PAA/ZnONPs(SO42-) nanocomplex. Osmotic fragility test (OFT) involved detection of hemolysis of red blood cells exposed to 0.2% saline solution following incubation with the D-PAA/ZnONPs(SO42-) nanocomplex. Additional incubation of the nanocomplex in the presence or absence of either ascorbic acid or EGTA was used to reveal the implication of oxidative stress- or Ca2+-mediated mechanisms in D-PAA/ZnONPs(SO42-) nanocomplex-induced erythrotoxicity.Results. Hemocompatibility assessment of the D-PAA/ZnONPs(SO42-) nanocomplex revealed that it induced hemolysis and reduced resistance of erythrocytes to osmotic stress at concentrations of above 400 and 200 mg l-1, respectively. Oxidative stress- or Ca2+-mediated mechanisms were not involved in D-PAA/ZnONPs(SO42-) nanocomplex-induced hemolysis. Strikingly, the D-PAA/ZnONPs(SO42-) nanocomplex did not promote cell membrane scrambling, cell shrinkage and oxidative stress in red blood cells following the direct exposure for 24 h. Thus, the D-PAA/ZnONPs(SO42-) nanocomplex did not induce eryptosisin vitro. Eryptosis is generally considered to occur earlier than hemolysis in response to stress in order to prevent hemolytic cell death. Counterintuitively, our data suggest that hemolysis can be triggered by nanomaterials prior to eryptosis indicating that eryptosis and hemolysis assays should be used in combination for testing blood compatibility of nanomaterials.Conclusions. The D-PAA/ZnONPs(SO42-) nanocomplex has a good hemocompatibility profile at low concentrations. Hemocompatibility testing in nanotoxicology should include both eryptosis and hemolysis assays.

Assessment of Genotoxicity of Zinc Oxide Nanoparticles Using Mosquito as Test Model

The widespread applications of ZnO NPs in the different areas of science, technology, medicine, agriculture, and commercial products have led to increased chances of their release into the environment. This created a growing public concern about the toxicological and environmental effects of the nanoparticles. The impact of these NPs on the genetic materials of living organisms is documented in some cultured cells and plants, but there are only a few studies regarding this aspect in animals. In view of this, the present work regarding the assessment of the genotoxicity of zinc oxide nanoparticles using the mosquito Culex quinquefaciatus has been taken up. Statistically significant chromosomal aberrations over the control are recorded after the exposure of the fourth instar larvae to a dose of less than LD20 for 24 h. In order to select this dose, LD20 of ZnO NPs for the mosquito is determined by Probit analysis. Lacto-aceto-orcein stained chromosomal preparations are made from gonads of adult treated and control mosquitoes. Both structural aberrations, such as chromosomal breaks, fragments, translocations, and terminal fusions, resulting in the formation of rings and clumped chromosomes, and numerical ones, including hypo- and hyper-aneuploidy at metaphases, bridges, and laggards at the anaphase stage are observed. The percentage frequency of abnormalities in the shape of sperm heads is also found to be statistically significant over the controls. Besides this, zinc oxide nanoparticles are also found to affect the reproductive potential and embryo development as egg rafts obtained from the genetic crosses of ZnO nanoparticle-treated virgin females and normal males are small in size with a far smaller number of eggs per raft. The percentage frequencies of dominant lethal mutations indicated by the frequency of unhatched eggs are also statistically significant (p < 0.05) over the control. The induction of abnormalities in all of the three short-term assays studied during the present piece of work indicates the genotoxic potential of ZnO NPs, which cannot be labeled absolutely safe, and this study pinpoints the need to develop strategies for the protection of the environment and living organisms thriving in it.

Zinc oxide nanoparticles disrupt development and function of the olfactory sensory system impairing olfaction-mediated behaviour in zebrafish

Zinc (Zn) is an essential metal present in numerous enzymes throughout the body, playing a vital role in animal and human health. However, the increasing use of zinc oxide nanomaterials (ZnONPs) in a diverse range of products has raised concerns regarding their potential impacts on health and the environment. Despite these concerns, the toxicity of ZnONP exposure on animal health remain poorly understood. To help address this knowledge gap, we have developed a highly sensitive oxidative stress (OS) biosensor zebrafish capable of detecting cell/tissue-specific OS responses to low doses of various oxidative stressors, including Zn, in a live fish embryo. Using live-imaging analysis with this biosensor zebrafish embryo, we discovered that the olfactory sensory neurons in the brain are especially sensitive to ZnOP exposure. Furthermore, through studies monitoring neutrophil migration and neuronal activation in the embryonic brain and via behaviour analysis, we have found that sub-lethal doses of ZnONPs (ranging from 0.033 to 1 mg/L nominal concentrations), which had no visible effect on embryo growth or morphology, cause significant localised inflammation, disrupting the neurophysiology of olfactory brain tissues and ultimately impaired olfaction-mediated behaviour. Collectively, these findings establish a potent and important effect mechanism for ZnONP toxicity, indicating the olfactory sensory system as the primary target for ZnONPs as an environmental toxicant in aquatic environments. Our result also highlights that even low doses of ZnONPs can have detrimental effects on the olfactory sensory system, surpassing previous expectations. The importance of olfaction in environment sensing, sex behaviours and overall fitness across species raises concerns about the potential impact of ZnONPs on olfaction-mediated brain function and behaviour in animals and humans. Our study emphasises the need for greater consideration of the potential risks associated with these nanomaterials.

Characterization, dose dependent assessment of hepatorenal oxidative stress, hematological parameters and histopathological divulging of the hepatic damages induced by Zinc oxide nanoparticles (ZnO-NPs) in adult male Sprague Dawley rats

Nanoparticles are beneficial in many aspects to human life but their excessive use can cause various abnormalities. They dispose in the environment through transport, industrial and agricultural usage and enter in living body through dermal, respiratory route or ingested with the lipsticks and there higher concentration produces toxicity. Therefore, current study characterized ZnO-NPs to evaluate toxic ability by X-rays diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques and showed 29.83 and 35 nm size, respectively with hexagonal crystalline structure. LC50 value of ZnO-NPs was also evaluated as 72.48 ± 10.33 mg/kg BW. Male Sprague Dawley (Post weaning) rats were divided into five groups with five rats in each group. Control (C) group received no treatment, placebo (S) group received normal saline (0.9% sodium chloride) intraperitoneally and three treated groups received different levels of ZnO- NPs intraperitoneally at the dose of either 10 or 20 or 30 mg/kg for 21 days on alternate days and named as 1G1, 1G2 and 1G3, respectively for the assessment of toxicity for better understanding of precautionary measures in future. Oxidative stress enzymes of liver and kidney, hepatorenal function enzymes and hematological parameters along with hepatic histology were measured at the end of the experiment. Results showed highly significant variations in all parameters in a dose dependent manner as compared to control group while groups receiving 10 or 20 mg/kg of ZnO-NPs showed low to moderate pathological changes in both organs. Liver histological analysis showed congestion, necrosis, hemorrhage, RBC's accumulations; inflammatory cells infiltration and severe abnormalities in high dose group while medium, low dose group showed moderate and least effects, respectively. It is concluded that ZnO-NPs are highly toxic at more concentration so their careful usage is needed in daily routine.

Modulatory effect of thymol on the immune response and susceptibility to Aeromonas hydrophila infection in Nile tilapia fish exposed to zinc oxide nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) have many exciting properties that make their use in a continuous increase in various biomedical, industrial, and agricultural applications. This is associated with accumulation in the aquatic ecosystems and fish exposure with consequent deleterious effects. To determine the potential of thymol to counteract the immunotoxic effects of ZnO-NPs, Oreochromis niloticus was exposed to ZnO-NPs (⅕ LC₅₀ =1.14 mg/L, for 28 days) with or without feeding a thymol-incorporated diet (1 or 2 g/kg diet). Our data demonstrated a reduction of aquaria water quality, leukopenia, and lymphopenia with a decrease in serum total protein, albumin, and globulin levels in exposed fish. At the same time, the stress indices (cortisol and glucose) were elevated in response to ZnO-NPs exposure. The exposed fish also revealed a decline in serum immunoglobulins, nitric oxide, and the activities of lysozyme and myeloperoxidase, in addition to reduced resistance to the Aeromonas hydrophila challenge. The RT-PCR analysis showed downregulation of antioxidant (SOD) superoxide dismutase and (CAT) catalase gene expression in the liver tissue with overexpression of the immune-related genes (TNF-α and IL-1β). Importantly, we found that thymol markedly protected against ZnO-NPs-induced immunotoxicity in fish co-supplemented with thymol (1 or 2 g/kg diet) in a dose-dependent manner. Our data confirm the immunoprotective and antibacterial effects of thymol in ZnO-NPs exposed fish, supporting the potential utility of thymol as a possible immunostimulant agent.

Calcium phosphates from fish bones in sunscreen: An LCA and toxicity study of an emerging material for circular economy

The use of sustainable and natural materials is an ever-increasing trend in cosmetic. Natural calcium phosphate (CaP-N) from food by-products and especially from fisheries (i.e., bones), has been suggested as a sustainable option to chemicals commonly used in cosmetic products, in particular to UV-filters in sunscreens. However, the environmental benefits and impacts of its production and use are still uncertain as they have never been quantified. In this paper, we report on toxicological characterization of CaP-N produced from incineration of fish meal in a pilot scale plant. Furthermore, we quantified the environmental burdens linked to the partial substitution of UV-filters by CaP-N through the life cycle assessment (LCA) comparing CaP-N with zinc oxide nanoparticles (ZnO NPs) as alternative option. CaP-N consists in a biphasic mixture 53:47 of hydroxyapatite:β-tricalcium phosphate, and is made of round particles with a diameter in the range of a few microns. Toxicity tests on 4 aquatic species (Dunaliella tertiolecta, Tigriopus fulvus, Corophium insidiosum and Gammarus aequicauda) revealed that CaP-N does not produce any adverse effect, all the species showing EC/LC50 values higher than 100 mg L^-1. Moreover, during the 96 h acute toxicity test on C. insidiosum, which is a tube-building species, the specimens built their tubes with the available CaP-N, further attesting the non-toxicity of the material. The LCA study showed that the environmental performance of CaP-N is better than that of ZnO NPs for 11 out of 16 impact categories analysed in this study, especially for the categories Ecotoxicity and Eutrophication of freshwaters (an order of magnitude lower), and with the exception of fossil resources for which CaP-N has a significantly higher impact than ZnO NPs (+140 %). Concluding, our study demonstrates that the replacement of ZnO NPs with CaP-N thermally extracted from fish bones in cosmetic products can increase their safety and sustainability.

3D printed neural tissues with in situ optical dopamine sensors

Engineered neural tissues serve as models for studying neurological conditions and drug screening. Besides observing the cellular physiological properties, in situ monitoring of neurochemical concentrations with cellular spatial resolution in such neural tissues can provide additional valuable insights in models of disease and drug efficacy. In this work, we demonstrate the first three-dimensional (3D) tissue cultures with embedded optical dopamine (DA) sensors. We developed an alginate/Pluronic F127 based bio-ink for human dopaminergic brain tissue printing with tetrapodal-shaped-ZnO microparticles (t-ZnO) additive as the DA sensor. DA quenches the autofluorescence of t-ZnO in physiological environments, and the reduction of the fluorescence intensity serves as an indicator of the DA concentration. The neurons that were 3D printed with the t-ZnO showed good viability, and extensive 3D neural networks were formed within one week after printing. The t-ZnO could sense DA in the 3D printed neural network with a detection limit of 0.137 μM. The results are a first step toward integrating tissue engineering with intensiometric biosensing for advanced artificial tissue/organ monitoring.

Metagenomics indicates abundance of biofilm related genes and horizontal transfer of multidrug resistant genes among bacterial communities in nano zinc oxide polluted soil

The unsafe and reckless disposal of metal oxide nanoparticles like ZnO (nZnO) into the soil could seriously impact bacterial behavioural responses and functions. Under such stress, biofilm formation is considered to be a robust mechanism for bacterial survival in soil. We examined the response of bacterial metagenomes in soils exposed to varying levels of Zn (50, 200, 500 and 1000 mg kg^-1) as nano Zn oxide (nZnO) in terms of biofilm genesis and regulation and their co-occurrences with multidrug resistance genes (MDRGs) and mobile genetic elements (MGEs). The size-specific effects of nZnO were verified using its bulk counterpart (bZnO). Both nZnO and bZnO facilitated profusion of biofilm related genes (BGs) especially at higher Zn levels (500 and 1000 mg kg^-1 Zn), though maximum abundance was registered at a comparatively lower level under nZnO. In general, nZnO favoured an enhancement of genes involved in exopolysaccharide biosynthesis and attachment, while bZnO favoured genes related to capsule formation, chemotaxis and biofilm dispersion. Co-occurrence network analysis revealed significant positive correlations between abundances of BGs, MDRGs and MGEs, indicating an enhanced probability for horizontal gene transfer of MDRGs in nZnO polluted soils.

Biosynthesis, Characterization, and Augmented Anticancer Activity of ZrO2 Doped ZnO/rGO Nanocomposite

Fabrication of ZnO nanoparticles (NPs) via green process has received enormous attention for its application in biomedicine. Here, a simple and cost-effective green route is reported for the synthesis of ZrO₂-doped ZnO/reduced graphene oxide nanocomposites (ZnO/ZrO₂/rGO NCs) exploiting ginger rhizome extract. Our aim was to improve the anticancer performance of ZnO/ZrO₂/rGO NCs without toxicity to normal cells. The preparation of pure ZnO NPs, ZnO/ZrO₂ NCs, and ZnO/ZrO₂/rGO NCs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), photoluminescence (PL), and dynamic light scattering (DLS). XRD spectra of ZnO/ZrO₂/rGO NCs exhibited two distinct sets of diffraction peaks, ZnO wurtzite structure, and ZrO₂ phases (monoclinic + tetragonal). The SEM and TEM data show that ZrO₂-doped ZnO particles were uniformly distributed on rGO sheets with the excellent quality of lattice fringes without alterations. PL spectra intensity and particle size of ZnO decreased after ZrO₂-doping and rGO addition. DLS data demonstrated that green prepared samples show excellent colloidal stability in aqueous suspension. Biological results showed that ZnO/ZrO₂/rGO NCs display around 3.5-fold higher anticancer efficacy in human lung cancer (A549) and breast cancer (MCF7) cells than ZnO NPs. A mechanistic approach suggested that the anticancer response of ZnO/ZrO₂/rGO NCs was mediated via oxidative stress evident by the induction of the intracellular reactive oxygen species level and the reduction of the glutathione level. Moreover, green prepared nanostructures display good cytocompatibility in normal cell lines; human lung fibroblasts (IMR90) and breast epithelial (MCF10A) cells. However, the cytocompatibility of ZnO/ZrO₂/rGO NCs in normal cells was better than those of pure ZnO NPs and ZnO/ZrO₂ NCs. Augmented anticancer potential and improved cytocompatibility of ZnO/ZrO₂/rGO NCs was due to ginger extract mediated beneficial synergism between ZnO, ZrO₂, and rGO. This novel investigation emphasizes the significance of medicinal herb mediated ZnO-based NCs synthesis for biomedical research.

Comparative study on the effects of micro- and nano-sized zinc oxide supplementation on zinc-deficient mice

BACKGROUND

Zinc (Zn) is an essential cofactor for physiological homeostasis in the body. Zn oxide (ZnO), an inorganic compound that supplies Zn, exists in various sizes, and its bioavailability may vary depending on the size in vivo. However, comparative studies on the nutritional effects of micro-sized ZnO (M-ZnO) and nano-sized ZnO (N-ZnO) supplementation on Zn deficiency (ZnD) animal models have not been reported.

OBJECTIVES

This study investigated the nutritional bioavailability of N-ZnO and M-ZnO particles in dietary-induced ZnD mice.

METHODS

Animals were divided into six experimental groups: normal group, ZnD control group, and four ZnO treatment groups (Nano-Low, Nano-High, Micro-Low, and Micro-High). After ZnD induction, N-ZnO or M-ZnO was administered orally every day for 4 weeks.

RESULTS

ZnD-associated clinical signs almost disappeared 7 days after N-ZnO or M-ZnO administration. Serum Zn concentrations were higher in the Nano-High group than in the ZnD and M-ZnO groups on day 7 of ZnO treatment. In the liver and testis, Nano-Low and Nano-High groups showed significantly higher Zn concentrations than the other groups after 14-day treatment. ZnO supplementation increased Mt-1 mRNA expression in the liver and testis and Mt-2 mRNA expression in the liver. Based on hematoxylin-and-eosin staining results, N-ZnO supplementation alleviated histological damage induced by ZnD in the testis and liver.

CONCLUSIONS

This study suggested that N-ZnO can be utilized faster than M-ZnO for nutritional restoration at the early stage of ZnD condition and presented Mt-1 as an indicator of Zn status in the serum, liver, and testis.

Assessment of the Antitumor Activity of Green Biosynthesized Zinc Nanoparticles as Therapeutic Agent Against Renal Cancer in Rats

Zinc nanoparticles (Zn-NPs) have garnered a great deal of attention as potential cancer therapy. The use of microorganisms in the synthesis of nanoparticles emerges as an eco-friendly and exciting approach. This study was designed to assess biosynthesized Zn-NPs as therapeutic agent against kidney cancer induced by ferric-nitrilotriacetate (Fe-NTA) in rats.Zn-NPs were synthesized from edible mushroom then characterized by transmission electron microscopy analysis, dynamic light scattering, and Fourier transform infrared spectroscopy. Rats were divided into 4 different groups: group I (control), group II (Fe-NTA group), group III (Zn-NPs group), and group IV (Fe-NTA + Zn-NPs group). Animals were sacrificed then kidney and liver function tests, MDA level, glutathione, glutathione peroxidase, and superoxide dismutase activities were measured by using colorimetric methods. Caspase-3 level and carcinoembryonic antigen concentration were measured by using ELISA. Finally, DNA fragmentation was visualized by using agarose gel electrophoresis.Treatment with Zn-NPs significantly suppressed renal oxidative stress by restoring glutathione level, glutathione peroxidase, and superoxide dismutase activities and ameliorated oxidative damage parameters of lipid peroxidation as well as renal toxicity markers. Molecular and tumor markers showed significant improvement with respect to induction group, and this was well appreciated with the histopathological alteration findings in the treated groups.Microbial synthesized Zn-NPs possess antitumor-promoting activity against Fe-NTA-induced toxicity and carcinogenesis, which should be evaluated in a clinical study.

On the In Vitro and In Vivo Hazard Assessment of a Novel Nanomaterial to Reduce the Use of Zinc Oxide in the Rubber Vulcanization Process

Zinc oxide (ZnO) is the most efficient curing activator employed in the industrial rubber production. However, ZnO and Zn(II) ions are largely recognized as an environmental hazard being toxic to aquatic organisms, especially considering Zn(II) release during tire lifecycle. In this context, aiming at reducing the amount of microcrystalline ZnO, a novel activator was recently synthetized, constituted by ZnO nanoparticles (NPs) anchored to silica NPs (ZnO-NP@SiO₂-NP). The objective of this work is to define the possible hazards deriving from the use of ZnO-NP@SiO₂-NP compared to ZnO and SiO₂ NPs traditionally used in the tire industry. The safety of the novel activators was assessed by in vitro testing, using human lung epithelial (A549) and immune (THP-1) cells, and by the in vivo model zebrafish (Danio rerio). The novel manufactured nanomaterial was characterized morphologically and structurally, and its effects evaluated in vitro by the measurement of the cell viability and the release of inflammatory mediators, while in vivo by the Fish Embryo Acute Toxicity (FET) test. Resulting data demonstrated that ZnO-NP@SiO₂-NP, despite presenting some subtoxic events, exhibits the lack of acute effects both in vitro and in vivo, supporting the safe-by-design development of this novel material for the rubber industry.

Nanoparticle-based toxicity in perishable vegetable crops: Molecular insights, impact on human health and mitigation strategies for sustainable cultivation

With the advancement of nanotechnology, the use of nanoparticles (NPs) and nanomaterials (NMs) in agriculture including perishable vegetable crops cultivation has been increased significantly. NPs/NMs positively affect plant growth and development, seed germination, plant stress management, and postharvest handling of fruits and vegetables. However, these NPs sometimes cause toxicity in plants by oxidative stress and excess reactive oxygen species production that affect cellular biomolecules resulting in imbalanced biological and metabolic processes in plants. Therefore, information about the mechanism underlying interactions of NPs with plants is important for the understanding of various physiological and biochemical responses of plants, evaluating phytotoxicity, and developing mitigation strategies for vegetable crops cultivation. To address this, recent morpho-physiological, biochemical and molecular insights of nanotoxicity in the vegetable crops have been discussed in this review. Further, factors affecting the nanotoxicity in vegetables and mitigation strategies for sustainable cultivation have been reviewed. Moreover, the bioaccumulation and biomagnification of NPs and associated phytotoxicity can cause serious effects on human health which has also been summarized. The review also highlights the use of advanced omics approaches and interdisciplinary tools for understanding the nanotoxicity and their possible use for mitigating phytotoxicity.

Insights into Ag-NPs-mediated pathophysiology and ultrastructural aberrations in ovarian tissues of darkling beetles

With the evolution of nanostructure materials, silver nanoparticles (Ag-NPs) emerged as the predominantly exploited nanomaterial in multifarious sectors due to their versatile properties. Along with the heightening applications of Ag-NPs, however, there is increasing concern over their indubitable toxicity towards the ecosystem, which indeed affects surrounding organisms and human health. In this study, we evaluated the detrimental effects of Ag-NPs in relation to Egyptian wild female beetles, Blaps polychresta, after injection with a single dose of Ag-NPs at different doses and monitoring for 30 days to determine the sublethal dose. Accordingly, the sublethal dose revealed the lowest negative influence was found at 0.03 mg/g body weight. The adverse impacts of Ag-NPs on the ovaries of female beetles were investigated by estimating the enzyme activities, DNA damage using a comet assay, and apoptosis by means of flow cytometry. Besides, the ultrastructural abnormalities were surveyed adopting transmission electron microscopy (TEM). The results manifested comet cells of 7.67 ± 0.88% and 22.33 ± 0.51 for Ag-NPs treated and control groups, respectively. Similarly, the data from flow cytometry demonstrated a substantial reduction in viable cells associated with a significant rise in apoptotic cells for the Ag-NPs treated group in comparison with the control group. Moreover, significant disturbances in enzyme activities for the treated group were perceived correlated with evident diminutions in antioxidant enzymes. Remarkably, the ultrastructural investigation emphasized these findings, exposing considerable deformities of the ovaries in the Ag-NPs treated group compared with the control group. To the best of our knowledge, this is the first report discussing the influence of Ag-NPs at the lowest dose on ovaries of B. polychresta. Collectively, our findings would significantly contribute to considering the critical effects of Ag-NPs at low levels, in addition to the potential use of B. polychresta as a good bio-indicator in ecotoxicological analyses.

Insights into the mapping of green synthesis conditions for ZnO nanoparticles and their toxicokinetics

Research on ZnO nanoparticles (NPs) has broad medical applications. However, the green synthesis of ZnO NPs involves a wide range of properties requiring optimization. ZnO NPs show toxicity at lower doses. This toxicity is a function of NP properties and pharmacokinetics. Moreover, NP toxicity and pharmacokinetics are affected by the species type and age of the animals tested. Physiologically based pharmacokinetic (PBPK) modeling offers a mechanistic platform to scrutinize the colligative effect of the interplay between these factors, which reduces the need for in vivo studies. This review provides a guide to choosing green synthesis conditions that result in minimal toxicity using a mechanistic tool, namely PBPK modeling.

Protective effects of Allium hirtifolium extract against foodborne toxicity of Zinc oxide nanoparticles in Common carp (Cyprinus carpio)

The use of nano-sized materials is increasingly growing, while consequent health and environmental risks are still disputed. On the other hand, plant extracts have been reported to improve fish general health status and enhance antioxidant capacity. Thus, the present study was aimed to assess potential effects of Allium hirtifolium extract (AHE) to fortify antioxidant responses of Common carp (Cyprinus carpio) exposed to foodborne Zinc oxide nanoparticles (ZnO-NPs). Five hundred and forty fish were randomly allocated into 18 tanks and received six diets including a basal diet (as control), basal diet incorporated with either 13 mg/kg (ZnO-25) or 26 mg/kg (ZnO-50) of ZnO-NPs, 1.5% AHE (AHE-1.5), and similar concentrations of ZnO-NPs plus AHE (ZnO-25-AHE) and (ZnO-50-AHE) for a period of 30 days. Results revealed that blood indices, stress biomarkers (glucose and cortisol), and antioxidant parameters and genes in AHE-1.5 group were significantly modulated and improved when compared to other groups (P < 0.05). In AHE-enriched groups, serum and liver tissue antioxidative parameters were enhanced as reflected in a noticeable decrease in malondialdehyde value and an increase in catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. However, current results showed that diets incorporated with ZnO-NPs elevated the stress parameters besides a significant reduction for most measured biochemical parameters and AHE supplementation ameliorated these effects in terms of improving antioxidant parameters. In ZnO-25-AHE, and ZnO-50-AHE, the values for expression of GPx were found significantly (P < 0.05) different from that of ZnO-25 and ZnO-50. On the contrary, SOD showed a non-significant difference (P > 0.05) among control, ZnO-25, and ZnO-50-AHE, also in-between ZnO-25 and ZnO-25-AHE. The present results indicate that AHE supplementation could trigger antioxidant responses both at tissue and molecular levels suggesting its outstanding protective effects against foodborne toxicity of ZnO-NPs in Common carp.

Enhanced Anticancer Performance of Eco-Friendly-Prepared Mo-ZnO/RGO Nanocomposites: Role of Oxidative Stress and Apoptosis

ZnO nanoparticles (NPs) have attracted great attention in cancer therapy because of their novel and tailorable physicochemical features. Pure ZnO NPs, molybdenum (Mo)-doped ZnO NPs, and Mo-ZnO/reduced graphene oxide nanocomposites (Mo-ZnO/RGO NCs) were prepared using a facile, inexpensive, and eco-friendly approach using date palm (Phoenix dactylifera L.) fruit extract. Anticancer efficacy of green synthesized NPs/NCs was examined in two different cancer cells. The potential mechanism of the anticancer activity of green synthesized NPs/NCs was explored through oxidative stress and apoptosis. The syntheses of pure ZnO NPs, Mo-ZnO NPs, and Mo-ZnO/RGO NCs were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and photoluminescence (PL). Dynamic light scattering (DLS) study indicated the excellent colloidal stability of green prepared samples. Mo-ZnO/RGO NCs exhibited threefold higher anticancer activity in human colon (HCT116) and breast (MCF7) cancer cells as compared to pure ZnO NPs. The anticancer activity of Mo-ZnO/RGO NCs was mediated through reactive oxygen species, p53, and the caspase-3 pathway. Moreover, cytocompatibility of Mo-ZnO/RGO NCs in human normal colon epithelial (NCM460) and normal breast epithelial cells (MCF10A) was much better than those of pure ZnO NPs. Altogether, green stabilized Mo-ZnO/RGO NCs exhibited enhanced anticancer performance and improved cytocompatibility because of green mediated good synergism between ZnO, Mo, and RGO. This study suggested the high nutritional value fruit-based facile preparation of ZnO-based nanocomposites for cancer therapy.

Albumin grafted coaxial electrosparyed polycaprolactone-zinc oxide nanoparticle for sustained release and activity enhanced antibacterial drug delivery

One of the most serious issues faced by the healthcare sector is the development of multidrug resistance among various pathogens. It is such that developing new and more capable drugs takes far too long to counter such resistance. In order to overcome these concerns, this study focused on improving upon the coaxial electrospraying process by producing cloxacillin loaded albumin polycaprolactone (PCL) with a ZnO coating for sustained and activity enhanced drug delivery. Albumin-grafted, polycaprolactone-coated, zinc oxide-loaded cloxacillin (APCL-CLOX-ZnO) nanoparticles with a diameter of 85–110 nm were obtained via a coaxial electrospray technique. The encapsulation efficiency of cloxacillin of ZnO-CLOX was found to be approximately 60%. The loading efficiencies of ZnO-CLOX and APCL-CLOX-ZnO were found to be 40% and 28% respectively. Albumin was employed in order to impart immune evasion properties to the formulation. Drug-loaded ZnO NPs were analyzed using SEM, TEM, FT-IR and TGA. This novel formulation was shown to possess sustained release characteristics owing to the PCL and albumin coatings, relative to uncoated counterparts. ZnO-CLOX and APCL-CLOX-ZnO exhibited 72% and 52% cloxacillin release within 24 h. APCL-CLOX-ZnO exhibited potent antimicrobial activity against S. epidermidis, B. cereus and P. aeruginosa and some activity against E. coli with inhibition zones 32 ± 1.4, 34 ± 0.3, 32 ± 0.6 and 11 ± 0.4 mm, respectively. Cytotoxicity studies against murine preosteoblast cells revealed that the albumin-PCL coating served to drastically reduce initial toxicity against healthy mammalian cells. In vitro lung deposition study showed 70% of APCL-CLOX-ZnO particles can reach up to the alveoli level. Therefore, this novel coaxial nanoformulation may serve as a promising drug delivery platform for the treatment of bacterial infections including respiratory tract complications.

Zinc oxide-cloxacillin incorporated nanoparticles coated with concentric layers of polycaprolactone and albumin via a coaxial electrospraying technique as an enhanced and sustained antimicrobial delivery system for respiratory infections.

Aquatic Toxicity Effects and Risk Assessment of 'Form Specific' Product-Released Engineered Nanomaterials

The study investigated the toxicity effects of 'form specific' engineered nanomaterials (ENMs) and ions released from nano-enabled products (NEPs), namely sunscreens, sanitisers, body creams and socks on Pseudokirchneriella subcapitata, Spirodela polyrhiza, and Daphnia magna. Additionally, risk estimation emanating from the exposures was undertaken. The ENMs and the ions released from the products both contributed to the effects to varying extents, with neither being a uniform principal toxicity agent across the exposures; however, the effects were either synergistic or antagonistic. D. magna and S. polyrhiza were the most sensitive and least sensitive test organisms, respectively. The most toxic effects were from ENMs and ions released from sanitisers and sunscreens, whereas body creams and sock counterparts caused negligible effects. The internalisation of the ENMs from the sunscreens could not be established; only adsorption on the biota was evident. It was established that ENMs and ions released from products pose no imminent risk to ecosystems; instead, small to significant adverse effects are expected in the worst-case exposure scenario. The study demonstrates that while ENMs from products may not be considered to pose an imminent risk, increasing nanotechnology commercialization may increase their environmental exposure and risk potential; therefore, priority exposure cases need to be examined.

Environmental Risk Assessment of Vehicle Exhaust Particles on Aquatic Organisms of Different Trophic Levels

Vehicle emission particles (VEPs) represent a significant part of air pollution in urban areas. However, the toxicity of this category of particles in different aquatic organisms is still unexplored. This work aimed to extend the understanding of the toxicity of the vehicle exhaust particles in two species of marine diatomic microalgae, the planktonic crustacean Artemia salina, and the sea urchin Strongylocentrotus intermedius. These aquatic species were applied for the first time in the risk assessment of VEPs. Our results demonstrated that the samples obtained from diesel-powered vehicles completely prevented egg fertilization of the sea urchin S. intermedius and caused pronounced membrane depolarization in the cells of both tested microalgae species at concentrations between 10 and 100 mg/L. The sample with the highest proportion of submicron particles and the highest content of polycyclic aromatic hydrocarbons (PAHs) had the highest growth rate inhibition in both microalgae species and caused high toxicity to the crustacean. The toxicity level of the other samples varied among the species. We can conclude that metal content and the difference in the concentrations of PAHs by itself did not directly reflect the toxic level of VEPs, but the combination of both a high number of submicron particles and high PAH concentrations had the highest toxic effect on all the tested species.

Comparative toxicity of ionic and nanoparticulate zinc in the species Cymodoce truncata, Gammarus aequicauda and Paracentrotus lividus

Due to the continuous development, production and consumption of nanoparticles (NPs), their release, fate and effects in marine coastal environment can represent a major concern. The aim of this study was to evaluate the toxicity of ZnO nanoparticles (ZnO NPs) and compare it to bulk ZnSO4 on three macroinvertebrates: the isopod Cymodoce truncata (i.e. used for the first time in ecotoxicology), the amphipod Gammarus aequicauda and the sea urchin Paracentrotus lividus. This study showed concentration- and time-dependent relationships for all biological models for both ZnO NPs and ZnSO4. Both Zn forms elicited high toxicity to G. aequicauda and C. truncata juveniles, but ZnO NPs induced comparable responses to both species (96h-LC50 = 0.30 and 0.37 mg/L for G. aequicauda and C. truncata, respectively; p > 0.05), while differences were found after ZnSO4 exposure (96h-LC50 = 0.28 and 0.63 mg/L, respectively; p < 0.05). ZnO NPs generated sub-lethal effects on P. lividus embryos (72h-EC50 = 0.04 (0.03, 0.05) mg/L), not significantly different from ZnSO4 ones (72h-EC50 = 0.06 (0.05, 0.07) mg/L). Effects of ZnO NPs were similar to existing literature data for other testing species. C. truncata can be considered as a promising new biological model in (nano)ecotoxicology.

Carbon Dots as an Emergent Class of Antimicrobial Agents

Antimicrobial resistance is a recognized global challenge. Tools for bacterial detection can combat antimicrobial resistance by facilitating evidence-based antibiotic prescribing, thus avoiding their overprescription, which contributes to the spread of resistance. Unfortunately, traditional culture-based identification methods take at least a day, while emerging alternatives are limited by high cost and a requirement for skilled operators. Moreover, photodynamic inactivation of bacteria promoted by photosensitisers could be considered as one of the most promising strategies in the fight against multidrug resistance pathogens. In this context, carbon dots (CDs) have been identified as a promising class of photosensitiser nanomaterials for the specific detection and inactivation of different bacterial species. CDs possess exceptional and tuneable chemical and photoelectric properties that make them excellent candidates for antibacterial theranostic applications, such as great chemical stability, high water solubility, low toxicity and excellent biocompatibility. In this review, we will summarize the most recent advances on the use of CDs as antimicrobial agents, including the most commonly used methodologies for CD and CD/composites syntheses and their antibacterial properties in both in vitro and in vivo models developed in the last 3 years.

Organ-on-a-chip technology for nanoparticle research

The last two decades have witnessed explosive growth in the field of nanoengineering and nanomedicine. In particular, engineered nanoparticles have garnered great attention due to their potential to enable new capabilities such as controlled and targeted drug delivery for treatment of various diseases. With rapid progress in nanoparticle research, increasing efforts are being made to develop new technologies for in vitro modeling and analysis of the efficacy and safety of nanotherapeutics in human physiological systems. Organ-on-a-chip technology represents the most recent advance in this effort that provides a promising approach to address the limitations of conventional preclinical models. In this paper, we present a concise review of recent studies demonstrating how this emerging technology can be applied to in vitro studies of nanoparticles. The specific focus of this review is to examine the use of organ-on-a-chip models for toxicity and efficacy assessment of nanoparticles used in therapeutic applications. We also discuss challenges and future opportunities for implementing organ-on-a-chip technology for nanoparticle research.

Assessment of the In Vivo Release and Biocompatibility of Novel Vesicles Containing Zinc in Rats

This paper is focused on the in vivo release and biocompatibility evaluation in rats of some novel systems entrapping zinc chloride in lipid vesicles. The particles were prepared by zinc chloride immobilization inside lipid vesicles made using phosphatidylcholine, stabilized with 0.5% chitosan solution, and dialyzed for 10 h to achieve a neutral pH. The submicrometric systems were physico-chemically characterized. White Wistar rats, assigned into four groups of six animals each, were treated orally with a single dose, as follows: Group I (control): deionized water 0.3 mL/100 g body weight; Group II (Zn): 2 mg/kg body weight (kbw) zinc chloride; Group III (LV-Zn): 2 mg/kbw zinc chloride in vesicles; Group IV (LVC-Zn): 2 mg/kbw zinc chloride in vesicles stabilized with chitosan. Haematological, biochemical, and immune parameters were assessed after 24 h and 7 days, and then liver fragments were collected for histopathological examination. The use of zinc submicrometric particles-especially those stabilized with chitosan-showed a delayed zinc release in rats. No substantial changes to blood parameters, plasma biochemical tests, serum complement activity, or peripheral neutrophils phagocytic capacity were noted; moreover, the tested substances did not induce liver architectural disturbances. The obtained systems provided a delayed release of zinc, and showed good biocompatibility in rats.

ZnO Nanoparticles-Modified Dressings to Inhibit Wound Pathogens

Zinc oxide (ZnO) nanoparticles (NPs) have been investigated for various skin therapies in recent years. These NPs can improve the healing and modulate inflammation in the wounds, but the mechanisms involved in such changes are yet to be known. In this study, we have designed a facile ZnO nano-coated dressing with improved antimicrobial efficiency against typical wound pathogens involved in biofilm and chronic infections. ZnO NPs were obtained by hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm effects were evaluated against laboratory and clinical isolates of significant Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) opportunistic pathogens, by quantitative methods. Our results have shown that the developed dressings have a high antibacterial efficiency after 6–24 h of contact when containing 0.6 and 0.9% ZnO NPs and this effect is similar against reference and clinical isolates. Moreover, biofilm development is significantly impaired for up to three days of contact, depending on the NPs load and microbial species. These results show that ZnO-coated dressings prevent biofilm development of main wound pathogens and represent efficient candidates for developing bioactive dressings to fight chronic wounds.

Effectiveness and safety of zinc oxide nanoparticle-coated socks compared to uncoated socks for the prevention of pitted keratolysis: a double-blinded, randomized, controlled trial study

BACKGROUND

Pitted keratolysis (PK) and bromodosis have negative impacts on the quality of life especially for military personnel. The antibacterial efficacy and safety of zinc oxide nanoparticles (ZnO-NPs) make them a suitable additive for textiles. We aim to establish the ability of ZnO-NP-coated socks to prevent PK and bromodosis in a real-life setting.

MATERIALS AND METHODS

A double-blinded, randomized, controlled trial was conducted in January 2019. Naval cadets assigned to a 14-day field training course were randomly allocated to either a ZnO-NP-coated or an uncoated-sock group. They completed questionnaires evaluating behavioral risk factors and self-assessed foot odor levels using a visual analogue scale (VAS); intervention-blinded dermatologists also performed foot examinations. They reassessed their odor levels and had their feet re-examined upon completion of the training course.

RESULTS

The 148 cadets enrolled for the study were allocated to two groups of 74 each. The ZnO-NP-coated sock participants demonstrated significantly less PK development than uncoated socks (P = 0.05). There was a reduction of the foot odor levels in both groups, as measured by the VAS, without statistical difference. However, the uncoated sock group experienced more foot odor with a significantly greater negative effect on their daily lives (P = 0.04) than the ZnO-NP-coated sock group.

CONCLUSIONS

ZnO-NP-coated socks proved their efficacy in inhibiting the development of PK for military personnel.

Environmental Photocatalytic Degradation of Antidepressants with Solar Radiation: Kinetics, Mineralization, and Toxicity

This work is focused on the kinetics, mineralization, and toxicological assessments of the antidepressant drug amitriptyline hydrochloride (AMI) in UV or solar illuminated aqueous suspensions of ZnO, TiO₂ Degussa P25, and TiO₂ Hombikat. ZnO was proven to be the most effective photocatalyst, and it was used for all further experiments under solar irradiation. The highest reaction rate was observed at 1.0 mg/mL of catalyst loading. In the investigated initial concentration range (0.0075–0.3000 mmol/L), the degradation rate of AMI increased with the increase of initial concentration in the investigated range. The effects of H₂O₂, (NH₄)₂S₂O₈, and KBrO₃, acting as electron acceptors, along with molecular oxygen were also studied. By studying the effects of ethanol and NaI as a hydroxyl radical and hole scavenger, respectively, it was shown that the heterogeneous catalysis takes place mainly via free hydroxyl radicals. In the mineralization study, AMI photocatalytic degradation resulted in ~30% of total organic carbon (TOC) decrease after 240 min of irradiation; acetate and formate were produced as the organic intermediates; NH₄⁺, NO₃⁻, NO₂⁻ ions were detected as nitrogen byproducts. Toxicity assessment using different mammalian cell lines, showed that H-4-II-E was the most sensitive one.

Effective Strategies, Mechanisms, and Photocatalytic Efficiency of Semiconductor Nanomaterials Incorporating rGO for Environmental Contaminant Degradation

The water pollution problems severely affect the natural water resources due to the large disposal of dyes, heavy metals, antibiotics, and pesticides. Advanced oxidation processes (AOP) have been developed using semiconductor nanomaterials as photocatalysts for water treatment as an essential strategy to minimize environmental pollution. Significant research efforts have been dedicated over the past few years to enhancing the photocatalytic efficiencies of semiconductor nanomaterials. Graphene-based composites created by integrating reduced graphene oxide (rGO) into various semiconductor nanomaterials enable the unique characteristics of graphene, such as the extended range of light absorption, the separation of charges, and the high capacity of adsorption of pollutants. Therefore, rGO-based composites improve the overall visible-light photocatalytic efficiency and lead to a new pathway for high-performance photocatalysts’ potential applications. This brief review illustrates the strategies of combining rGO with various semiconductor nanomaterials and focuses primarily on modification and efficiency towards environmental contaminants.

Harmful effects of metal(loid) oxide nanoparticles

Abstract

The incorporation of nanomaterials (NMs), including metal(loid) oxide (MOx) nanoparticles (NPs), in the most diversified consumer products, has grown enormously in recent decades. Consequently, the contact between humans and these materials increased, as well as their presence in the environment. This fact has raised concerns and uncertainties about the possible risks of NMs to human health and the adverse effects on the environment. These concerns underline the need and importance of assessing its nanosecurity. The present review focuses on the main mechanisms underlying the MOx NPs toxicity, illustrated with different biological models: release of toxic ions, cellular uptake of NPs, oxidative stress, shading effect on photosynthetic microorganisms, physical restrain and damage of cell wall. Additionally, the biological models used to evaluate the potential hazardous of nanomaterials are briefly presented, with particular emphasis on the yeast Saccharomyces cerevisiae, as an alternative model in nanotoxicology. An overview containing recent scientific advances on cellular responses (toxic symptoms exhibited by yeasts) resulting from the interaction with MOx NPs (inhibition of cell proliferation, cell wall damage, alteration of function and morphology of organelles, presence of oxidative stress bio-indicators, gene expression changes, genotoxicity and cell dead) is critically presented. The elucidation of the toxic modes of action of MOx NPs in yeast cells can be very useful in providing additional clues about the impact of NPs on the physiology and metabolism of the eukaryotic cell. Current and future trends of MOx NPs toxicity, regarding their possible impacts on the environment and human health, are discussed.

Key points

• The potential hazardous effects of MOx NPs are critically reviewed.

• An overview of the main mechanisms associated with MOx NPs toxicity is presented.

• Scientific advances about yeast cell responses to MOx NPs are updated and discussed.