In vivo biodistribution and synergistic toxicity of silica nanoparticles and cadmium chloride in mice

Interactive effects of cadmium and titanium dioxide nanoparticles on hepatic tissue in rats: Ameliorative role of coenzyme 10 via modulation of the NF-κB and TNFα pathway

This study investigated the effect of oral dosing of titanium dioxide nanoparticles (TNPs) and cadmium (Cd2+) on rat liver and the potential protective role of coenzyme Q10 (CQ10) against TNPs and Cd2+-induced hepatic injury. Seventy male Sprague Dawley rats were divided into seven groups and orally given distilled water, corn oil, CQ10 (10 mg/kg b.wt), TNPs (50 mg/kg b.wt), Cd2+ (5 mg/kg b.wt), TNPs + Cd2+, or TNPs + Cd2++CQ10 by gastric gavage for 60 successive days. The results showed that individual or mutual exposure to TNPs and Cd2+ significantly increased the serum levels of various hepatic enzymes and lipids, depleted the hepatic content of antioxidant enzymes, and increased malondialdehyde. Moreover, the hepatic titanium and Cd2+ content were increased considerably in TNPs and/or Cd2+-exposed rats. Furthermore, marked histopathological perturbations with increased immunoexpression of tumor necrosis factor-alpha and nuclear factor kappa B were evident in TNPs and/or Cd2+-exposed rats. However, CQ10 significantly counteracted the damaging effect of combined exposure of TNPs and Cd2+ on the liver. The study concluded that TNPs and Cd2+ exposure harm hepatic function and its architecture, particularly at their mutual exposure, but CQ10 could be a candidate protective agent against TNPs and Cd2+ hepatotoxic impacts.

Implication of ferroptosis in hepatic toxicity upon single or combined exposure to polystyrene microplastics and cadmium

Microplastics (MPs) are a newly emerging type of pollutants. To date, MPs have been found in the atmosphere, soil, water, and even in human samples, posing a non-negligible threat to humans. Furthermore, multiple heavy metals have been found to co-exist with MPs or be absorbed by MPs. This leads to a widespread concern about their combined toxicity, which is currently elusive. Herein, we investigated the single or combined toxic effects of polystyrene MPs (PS-MPs) and cadmium chloride (CdCl2) on the liver and hepatocytes. After co-incubation, cadmium (Cd) can be absorbed by PS-MPs, resulting in physiochemical alterations of PS-MPs. In vivo and in vitro experiments revealed that PS-MPs solely or together with CdCl2 induced ferroptosis in hepatocytes, a newly defined programmed cell death characterized by lipid oxidation and iron accumulation. PS-MPs exerted more ferroptotic effect on hepatocytes than CdCl2, and combined exposure to PS-MPs and CdCl2 enhanced their ferroptotic effect, mainly by stimulating reactive oxygen species (ROS) production and inhibiting antioxidant activity. Upon single or combined exposure to PS-MPs and CdCl2, the induction of ferroptosis in hepatocytes can be inhibited by N-acetyl-cysteine (NAC, an ROS scavenger), deferoxamine (DFO, an iron chelator), and particularly ferrostatin-1 (Fer-1, a specific ferroptosis inhibitor). Fer-1 efficiently rescued the cell viability of hepatocytes upon exposure to PS-MPs and CdCl2 through enhancing the antioxidant system via upregulating GPX4 and SLC7A11. These findings would contribute to an in-depth understanding of the single and combined toxicity of microplastics and cadmium.

Co-exposure to environmentally relevant concentrations of cadmium and polystyrene nanoplastics induced oxidative stress, ferroptosis and excessive mitophagy in mice kidney

Nanoplastics (NPs) are defined as a group of emerging pollutants. However, the adverse effect of NPs and/or heavy metals on mammals is still largely unclear. Therefore, we performed a 35-day chronic toxicity experiment with mice to observe the impacts of exposure to Cadmium (Cd) and/or polystyrene nanoplastics (PSNPs). This study revealed that combined exposure to Cd and PSNPs added to the mice's growth toxicity and kidney damage. Moreover, Cd and PSNPs co-exposure obviously increased the MDA level and expressions of 4-HNE and 8-OHDG while decreasing the activity of antioxidase in kidneys via inhibiting the Nrf2 pathway and its downstream genes and proteins expression. More importantly, the results suggested for the first time that Cd and PSNPs co-exposure synergistically increased iron concentration in kidneys, and induced ferroptosis through regulating expression levels of SLC7A11, GPX4, PTGS2, HMGB1, FTH1 and FTL. Simultaneously, Cd and PSNPs co-exposure further increased the expression levels of Pink, Parkin, ATG5, Beclin1, and LC3 while significantly reducing the P62 expression level. In brief, this study found that combined exposure to Cd and PSNPs synergistically caused oxidative stress, ferroptosis and excessive mitophagy ultimately aggravating kidney damage in mice, which provided new insight into the combined toxic effect between heavy metals and PSNPs on mammals.

Understanding Nanomaterial-Liver Interactions to Facilitate the Development of Safer Nanoapplications

Nanomaterials (NMs) are widely used in commercial and medical products, such as cosmetics, vaccines, and drug carriers. Exposure to NMs via various routes such as dermal, inhalation, and ingestion has been shown to gain access to the systemic circulation, resulting in the accumulation of NMs in the liver. The unique organ structures and blood flow features facilitate the liver sequestration of NMs, which may cause adverse effects in the liver. Currently, most in vivo studies are focused on NMs accumulation at the organ level and evaluation of the gross changes in liver structure and functions, however, cell-type-specific uptake and responses, as well as the molecular mechanisms at cellular levels leading to effects at organ levels are lagging. Herein, the authors systematically review diverse interactions of NMs with the liver, specifically on major liver cell types including Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs), and hepatocytes as well as the detailed molecular mechanisms involved. In addition, the knowledge gained on nano-liver interactions that can facilitate the development of safer nanoproducts and nanomedicine is also reviewed.

Silica-coated magnetic-nanoparticle-induced cytotoxicity is reduced in microglia by glutathione and citrate identified using integrated omics

BACKGROUND

Nanoparticles have been utilized in brain research and therapeutics, including imaging, diagnosis, and drug delivery, owing to their versatile properties compared to bulk materials. However, exposure to nanoparticles leads to their accumulation in the brain, but drug development to counteract this nanotoxicity remains challenging. To date, concerns have risen about the potential toxicity to the brain associated with nanoparticles exposure via penetration of the brain blood barrier to address this issue.

METHODS

Here the effect of silica-coated-magnetic nanoparticles containing the rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)] were assessed on microglia through toxicological investigation, including biological analysis and integration of transcriptomics, proteomics, and metabolomics. MNPs@SiO2(RITC)-induced biological changes, such as morphology, generation of reactive oxygen species, intracellular accumulation of MNPs@SiO2(RITC) using transmission electron microscopy, and glucose uptake efficiency, were analyzed in BV2 murine microglial cells. Each omics data was collected via RNA-sequencing-based transcriptome analysis, liquid chromatography-tandem mass spectrometry-based proteome analysis, and gas chromatography- tandem mass spectrometry-based metabolome analysis. The three omics datasets were integrated and generated as a single network using a machine learning algorithm. Nineteen compounds were screened and predicted their effects on nanotoxicity within the triple-omics network.

RESULTS

Intracellular reactive oxygen species production, an inflammatory response, and morphological activation of cells were greater, but glucose uptake was lower in MNPs@SiO2(RITC)-treated BV2 microglia and primary rat microglia in a dose-dependent manner. Expression of 121 genes (from 41,214 identified genes), and levels of 45 proteins (from 5918 identified proteins) and 17 metabolites (from 47 identified metabolites) related to the above phenomena changed in MNPs@SiO2(RITC)-treated microglia. A combination of glutathione and citrate attenuated nanotoxicity induced by MNPs@SiO2(RITC) and ten other nanoparticles in vitro and in the murine brain, protecting mostly the hippocampus and thalamus.

CONCLUSIONS

Combination of glutathione and citrate can be one of the candidates for nanotoxicity alleviating drug against MNPs@SiO2(RITC) induced detrimental effect, including elevation of intracellular reactive oxygen species level, activation of microglia, and reduction in glucose uptake efficiency. In addition, our findings indicate that an integrated triple omics approach provides useful and sensitive toxicological assessment for nanoparticles and screening of drug for nanotoxicity.

Effects of Co-Exposure of Nanoparticles and Metals on Different Organisms: A Review

Wide nanotechnology applications and the commercialization of consumer products containing engineered nanomaterials (ENMs) have increased the release of nanoparticles (NPs) to the environment. Titanium dioxide, aluminum oxide, zinc oxide, and silica NPs are widely implicated NPs in industrial, medicinal, and food products. Different types of pollutants usually co-exist in the environment. Heavy metals (HMs) are widely distributed pollutants that could potentially co-occur with NPs in the environment. Similar to what occurs with NPs, HMs accumulation in the environment results from anthropogenic activities, in addition to some natural sources. These pollutants remain in the environment for long periods and have an impact on several organisms through different routes of exposure in soil, water, and air. The impact on complex systems results from the interactions between NPs and HMs and the organisms. This review describes the outcomes of simultaneous exposure to the most commonly found ENMs and HMs, particularly on soil and aquatic organisms.

Nano-cell and nano-pollutant interactions constitute key elements in nanoparticle-pollutant combined cytotoxicity

As the wide application of carbon nanoparticles (CNPs) and zinc oxide nanoparticles (ZnONPs), as well as ubiquitous chromium (Cr(VI)) pollution in environment, the chance of human exposure to CNPs/ZnONPs and their Cr(VI) adducts is enhanced. We therefore investigated the impacts of nano-cell and nano-Cr(VI) interactions on nanoparticle-Cr(VI) combined cytotoxicity in human lung epithelial (A549) cells. Our results showed that nano-cell and nano-pollutant interactions were the key elements in NP-pollutant combined cytotoxicity, as determined by cell death, oxidative stress and mitochondrial dysfunction. A strong adsorption of Cr(VI) on CNPs and reduction of Cr(VI) to Cr(III) were confirmed, resulting in the reduced cytotoxicity of CNP-Cr(VI) adducts. In contrast, ZnONPs caused the destruction of cell membranes so that more ZnONP-Cr(VI) adducts could enter the cells. Meantime, more Cr contents could be released from ZnONP-Cr(VI) adducts once entering cells and locating in lysosomes than that from CNP-Cr(VI) adducts. These two reasons together caused the enhanced cytotoxicity of ZnONP-Cr(VI) adducts. These findings indicate that the in-depth investigations on the interaction mechanisms are crucial to comprehensively understand the combined cytotoxicity of different NPs and pollutants.

Co-exposures of TiO2 nanoparticles and cadmium ions at non-lethal doses aggravates liver injury in mice with ConA-induced hepatitis

The wide applications of titanium dioxide nanoparticles (TNP) and ubiquitous cadmium (Cd) pollution increase the chances of their co-existence in the environment and also pose potential health risks to humans. However, toxicological understanding of effects of co-exposures of TNP and Cd to mammals is still lacking. In this study, non-lethal doses of TNP and CdCl2 were intravenously co-administered to healthy or Concanavalin A (ConA)-induced acute hepatitis mice. Co-exposures of TNP and CdCl2 increased the accumulation of Cd2+ in the liver of hepatitis mice, which was 1.42-fold higher than that of healthy mice. Co-exposures also caused liver damage only in hepatitis mice on the basis of histopathological and biochemical evidence. Further study showed that co-exposure upregulated hepatic oxidative stress, which further induced autophagy and apoptosis only in the liver of hepatitis mice. This finding underlines the potential toxicological consequences of co-exposures of TNP and CdCl2 in hepatitis sufferers.

Combined effects of nanoparticles and other environmental contaminants on human health - an issue often overlooked

Air pollution is considered as a major public health issue worldwide. It consists of a complex mixture of pollutants including nanoparticles to which we are increasingly exposed to due to the dramatic development of the nanotechnologies and their incidental or intentional release in the environment. Consequently, some concerns have raised about the combined toxicity of air particulates and other air pollutants on human health. However, the interactions between the contaminants and their resulting combined toxicity are often overlooked. Indeed, the biological effects triggered by nanoparticles are usually assessed focusing on individual nanoparticles, while their interaction with co-contaminants can deeply impact, either positively or negatively, their biodistribution, fate in the organism and toxicological profile (additive, synergistic or antagonistic responses). This paper presents a bibliographic review on the combined toxicity of nanoparticles and co-pollutants and discusses the underlying mechanisms. It also highlights the scarcity of data in the current literature, arguing for an urgent need to take into account the mixture effects to be more representative of real-life conditions for a better and accurate human health risk assessment and management.

Biodistribution, inter-/intra-cellular localization and respiratory dysfunction induced by Ti3C2 nanosheets: Involvement of surfactant protein down-regulation in alveolar epithelial cells

Two-dimensional Ti₃C₂ nanosheets have been extensively used in biomedical fields and are mostly designed to enter the circulatory system. However, few studies have focused on the in vivo anatomical location and physiological function of major organs on exposure to Ti₃C₂ nanosheets. This study attempts to determine whether and how Ti₃C₂ nanosheets disrupt the physiological function of the involved organs. Our studies demonstrated that Ti₃C₂ nanosheets were mainly distributed in the lungs and liver after entering circulation. In the lungs, they were retained in the cytoplasm of alveolar epithelial cells and endothelial cells, and inhibited pulmonary surfactant protein B (SP-B) expression on alveolar epithelial cell, causing increased airway resistance-induced respiratory disorder following a 28-day Ti₃C₂ nanosheet exposure. Furthermore, our data showed that Ti₃C₂ nanosheets did not cause abnormal proinflammatory cytokines and histopathological changes. These findings demonstrated that Ti₃C₂ nanosheets might disturb respiration without inflammatory responses and pathological lesions, suggesting that these effects may occur by decreasing SP-B-mediated airway resistance. This indicates that organ function maintenance differs from biological safety for Ti₃C₂ nanosheets, an important consideration during potential clinical application and human exposure.

Combined toxic effects of CBNPs and Pb on rat alveolar macrophage apoptosis and autophagy flux

Carbon black (CB) and heavy metals are the main components of Particulate Matter (PM). Although the individual toxicities of CB and heavy metals have been extensively studied, the combined toxicity is much less understood. In this study, we choose the nano carbon black (CBNPs) and Pb²⁺ to simulate fine particles in the atmosphere and study the combined toxic effect on rat alveolar macrophages. The data showed that CBNPs could adsorb Pb²⁺ to form CBNPs-Pb²⁺ complex and displayed an altered physical properties by particle characterization. CBNPs-Pb²⁺ synergistically induced rat alveolar macrophages apoptosis and blocked autophagy flux compared with CBNPs and Pb²⁺ individually. Consistent with this, CBNPs-Pb²⁺ could impair the mitochondrial membrane potential (MMP), activate apoptotic signaling pathways, inhibit lysosomal function.

The Size-dependent Cytotoxicity of Amorphous Silica Nanoparticles: A Systematic Review of in vitro Studies

With the increasing production and application of engineered amorphous silica nanoparticles (aSiNPs), people have more opportunities to be exposed to aSiNPs. However, the knowledge of its adverse health effects and related mechanisms is still limited, compared with the well-studied crystalline micron-sized silica. Since small differences in the physical–chemical properties of nanoparticles could cause significant differences in the toxic effect, it is important to distinguish how these variations influence the outcoming toxicity. Notably, particle size, as one of the essential characterizations of aSiNPs, is relevant to its biological activities. Thus, the aim of this systematic review was to summarize the relationship between the particle size of aSiNPs and its adverse biological effects. In order to avoid the influence of complicated in vivo experimental conditions on the toxic outcome, only in vitro toxicity studies which reported on the cytotoxic effect of different sizes aSiNPs were included. After the systematic literature retrieval, selection, and quality assessment process, 76 eligible scientific papers were finally included in this review. There were 76% of the studies that concluded a size-dependent cytotoxicity of aSiNPs, in which smaller-sized aSiNPs possessed greater toxicity. However, this trend could be modified by certain influence factors, such as the synthetic method of aSiNPs, particle aggregation state in cell culture medium, toxicity endpoint detection method, and some other experimental conditions. The effects of these influence factors on the size-dependent cytotoxicity of aSiNPs were also discussed in detail in the present review.

Toxicity to RAW264.7 Macrophages of Silica Nanoparticles and the E551 Food Additive, in Combination with Genotoxic Agents

Synthetic amorphous silica (SAS) is used in a plethora of applications and included in many daily products to which humans are exposed via inhalation, ingestion, or skin contact. This poses the question of their potential toxicity, particularly towards macrophages, which show specific sensitivity to this material. SAS represents an ideal candidate for the adsorption of environmental contaminants due to its large surface area and could consequently modulate their toxicity. In this study, we assessed the toxicity towards macrophages and intestinal epithelial cells of three SAS particles, either isolated SiO₂ nanoparticles (LS30) or SiO₂ particles composed of agglomerated-aggregates of fused primary particles, either food-grade (E551) or non-food-grade (Fumed silica). These particles were applied to cells either alone or in combination with genotoxic co-contaminants, i.e., benzo[a]pyrene (B[a]P) and methane methylsulfonate (MMS). We show that macrophages are much more sensitive to these toxic agents than a non-differenciated co-culture of Caco-2 and HT29-MTX cells, used here as a model of intestinal epithelium. Co-exposure to SiO₂ and MMS causes DNA damage in a synergistic way, which is not explained by the modulation of DNA repair protein mRNA expression. Together, this suggests that SiO₂ particles could adsorb genotoxic agents on their surface and, consequently, increase their DNA damaging potential.

All Roads Lead to the Liver: Metal Nanoparticles and Their Implications for Liver Health

Metal nanoparticles (NPs) are frequently encountered in daily life, and concerns have been raised about their toxicity and safety. Among which, they naturally accumulate in the liver after introduction into the body, independent of the route of administration. Some NPs exhibit intrinsic pharmaceutical effects that are related to their physical parameters, and their inadvertent accumulation in the liver can exert strong effects on liver function and structure. Even as such physiological consequences are often categorically dismissed as toxic and deleterious, there are cell type-specific and NP-specific biological responses that elicit distinctive pharmacological consequences that can be harnessed for good. By limiting the scope of discussion to metallic NPs, this work attempts to provide a balanced perspective on their safety in the liver, and discusses both possible therapeutic benefits and potential accidental liver damage arising from their interaction with specific parenchymal and nonparenchymal cell types in the liver.

Influence of silica nanoparticles on cadmium-induced cytotoxicity, oxidative stress, and apoptosis in human liver HepG2 cells

Extensive application of amorphous silica nanoparticles (Si NPs) and ubiquitous cadmium (Cd) may increase their chances of coexposure to humans. Studies on combined effects of Si NPs and Cd in human cells are very limited. We investigated the potential mechanism of toxicity caused by coexposure of amorphous Si NPs and Cd in human liver (HepG2) cells. Results showed that Si NPs were not toxic to HepG2. However, Cd induced significant toxicity in HepG2 cells. Interestingly, we observed that a noncytotoxic concentration of Si NPs potentiated the cytotoxicity of Cd in HepG2 cells. We further noticed that coexposure of Si NPs and Cd augmented oxidative stress evidenced by the generation of oxidants (reactive oxygen species, hydrogen peroxide, and lipid peroxidation) and depletion of antioxidants (glutathione level and antioxidant enzyme activity). Coexposure of Si NPs and Cd also augmented mitochondria-mediated apoptosis in HepG2 cells indicated by altered regulation of apoptotic genes (p53, bax, bcl-2, caspase-3, and caspase-9) along with reduced mitochondrial membrane potential. Interaction data indicated that Si NPs facilitate the cellular uptake of Cd due to its strong adsorption on the surface of Si NPs. Hence, Si NPs increased the bioaccumulation and toxicity of Cd in HepG2 cells. This study warrants further research to explore the potential mechanisms of combined toxicity of Si NPs and Cd in animal models.

TiO2 nanoparticles potentiated the cytotoxicity, oxidative stress and apoptosis response of cadmium in two different human cells

Widespread application of titanium dioxide nanoparticles (nTiO₂) and ubiquitous cadmium (Cd) pollution may increase their chance of co-existence in the natural environment. Toxicological information on co-exposure of nTiO₂ and Cd in mammalian models is largely lacking. Hence, we studied the combined effects of nTiO₂ and Cd in human liver (HepG2) and breast cancer (MCF-7) cells. We observed that nTiO₂ did not produce toxicity to HepG2 and MCF-7 cells. However, moderate concentration of Cd exposure caused cytotoxicity to both cells. Interestingly, non-cytotoxic concentration of nTiO₂ effectively enhanced the oxidative stress response of Cd indicated by pro-oxidants generation (reactive oxygen species, hydrogen peroxide, and lipid peroxidation) and antioxidants depletion (glutathione level and glutathione reductase, superoxide dismutase, and catalase enzymes). Moreover, nTiO₂ potentiated the Cd-induced apoptosis in both cells suggested by altered expression of p53, bax, and bcl-2 genes along with low mitochondrial membrane potential. Cellular uptake results demonstrated that nTiO₂ facilitates the internalization of Cd into the cells. Overall, this study demonstrated that non-cytotoxic concentration of nTiO₂ enhanced the toxicological potential of Cd in human cells. Therefore, more attention should be paid on the combine effects of nTiO₂ and Cd on human health.

Oral Co-Exposures to zinc oxide nanoparticles and CdCl2 induced maternal-fetal pollutant transfer and embryotoxicity by damaging placental barriers

Synergistic toxicity from multiple environmental pollutants poses greater threat to humans, especially to susceptible pregnant population. Here we evaluated combined toxicity from environment pollutants zinc oxide nanoparticles (ZnO NPs) and cadmium chloride (CdCl₂) using two pregnant mice models established by oral administration during peri-implantation or organogenesis period. We found that exposures to combined pollutants only at organogenesis stage induced higher fetal deformity rate compared to co-exposures at peri-implantation stage. We further discovered that surface charge of ZnO NPs were modified after Cd²⁺ adsorption and the resulting nanoadducts caused more severe damages in placental barriers by causing shed endothelial cells and decreased expressions of tight junction proteins ZO1, occludin, claudin-4 and claudin-8. These cellular and molecular events enhanced maternal-fetal transfer of both pollutants and aggravated embryotoxicity. Our findings help elucidate synergistic embryotoxicity by nanoparticle/pollutant adducts and establish proper safety criteria for pregnant population in an era that nanotechnology-based products are widely used.

The effect of single and combined exposures to magnetite and polymorphous silicon dioxide nanoparticles on the human A549 cell line: in vitro study

The increasing trend of nanoparticle usage in science and technology has led to significant human exposure. Occupational exposure to iron oxides and silica dust has been reported in mining, manufacturing, construction, and pharmaceutical operations. The combined toxicological effects of nanoparticles and simultaneous exposure to other compounds have given rise to a new concern. Hence, the objective of this study was to investigate the toxicological effects of magnetite and polymorphous silicon dioxide nanoparticles in single and combined exposures. The polymorphous silicon dioxide nanoparticles were obtained from the milled quartz particles under 100 nm in diameter. The milled particles were purified through chloric and nitric acid wash processes. The toxic effects of the magnetite nanoparticles were investigated independently and in combination with quartz using the A₅₄₉ cell line for durations of 24 and 72 h, and using diverse concentrations of 10, 50, 100, and 250 μg/mL. MTT, ROS, mitochondrial membrane potential, and cell glutathione content assays were used to evaluate the amount of cell damage in this study. The statistical significance level in one-way ANOVA and independent t test was considered to be at the 5% confidence level. The size and purity of polymorphous silicon dioxide nanoparticles were measured by TEM and ICP-OES analysis, respectively. The particles' diameters were under 100 nm and demonstrated a purity of higher than 99%. The toxicity results of this study showed a dependency on concentration and exposure duration in reducing the cell viability, cellular glutathione content, and mitochondrial membrane potential, as well as increasing the ROS generation in single and combined exposures with magnetite and polymorphous silicon dioxide nanoparticles. The toxic effects of combined exposure to these nanoparticles were less than the single exposures, and statistically significant antagonistic interactions were detected. Combined exposure to polymorphous silicon dioxide and magnetite nanoparticles, in comparison with their single exposures, could affect health in an antagonistic manner. Since this study has been the first of its kind, further studies investigating the health effects of single and combined exposures to these compounds are needed to verify our findings. Generally, studies such as this one could contribute to the field of combined toxicity effects.

Co-exposure to the food additives SiO2 (E551) or TiO2 (E171) and the pesticide boscalid increases cytotoxicity and bioavailability of the pesticide in a tri-culture small intestinal epithelium model: Potential health implications

Many toxicity investigations have evaluated the potential health risks of ingested engineered nanomaterials (iENMs); however, few have addressed the potential combined effects of iENMs and other toxic compounds (e.g. pesticides) in food. To address this knowledge gap, we investigated the effects of two widely used, partly nanoscale, engineered particulate food additives, TiO2 (E171) and SiO2 (E551), on the cytotoxicity and cellular uptake and translocation of the pesticide boscalid. Fasting food model (phosphate buffer) containing iENM (1% w/w), boscalid (10 or 150 ppm), or both, was processed using a simulated in vitro oral-gastric-small intestinal digestion system. The resulting small intestinal digesta was applied to an in vitro tri-culture small intestinal epithelium model, and effects on cell layer integrity, viability, cytotoxicity and production of reactive oxygen species (ROS) were assessed. Boscalid uptake and translocation was also quantified by LC/MS. Cytotoxicity and ROS production in cells exposed to combined iENM and boscalid were greater than in cells exposed to either iENM or boscalid alone. More importantly, translocation of boscalid across the tri-culture cellular layer was increased by 20% and 30% in the presence of TiO2 and SiO2, respectively. One possible mechanism for this increase is diminished epithelial cell health, as indicated by the elevated oxidative stress and cytotoxicity observed in co-exposed cells. In addition, analysis of boscalid in digesta supernatants revealed 16% and 30% more boscalid in supernatants from samples containing TiO2 and SiO2, respectively, suggesting that displacement of boscalid from flocculated digestive proteins by iENMs may also contribute to the increased translocation.

Co-Exposure to SiO2 Nanoparticles and Arsenic Induced Augmentation of Oxidative Stress and Mitochondria-Dependent Apoptosis in Human Cells

Widespread application of silica nanoparticles (nSiO₂) and ubiquitous metalloid arsenic (As) may increase their chances of co-exposure to human beings in daily life. Nonetheless, studies on combined effects of nSiO₂ and As in human cells are lacking. We investigated the co-exposure effects of nSiO₂ and As in human liver (HepG2) and human fibroblast (HT1080) cells. Results showed that nSiO₂ did not cause cytotoxicity. However, exposure of As caused oxidative stress and apoptosis in both types of cells. Interesting results were that co-exposure of a non-cytotoxic concentration of nSiO₂ significantly augmented the As induced toxicity in both cells. Intracellular level of As was higher in the co-exposure group (nSiO₂ + As) than the As group alone, suggesting that nSiO₂ facilitates the cellular uptake of As. Co-exposure of nSiO₂ and As potentiated oxidative stress indicated by pro-oxidants generation (reactive oxygen species, hydrogen peroxide and lipid peroxidation) and antioxidants depletion (glutathione level, and glutathione reductase, superoxide dismutase and catalase activities). In addition, co-exposure of nSiO₂ and As also potentiated mitochondria-mediated apoptosis suggested by increased expression of p53, bax, caspase-3 and caspase-9 genes (pro-apoptotic) and decreased expression of bcl-2 gene (anti-apoptotic) along with depleted mitochondrial membrane potential. To the best of our knowledge, this is the first study showing that co-exposure of nSiO₂ and As induced augmentation of oxidative stress and mitochondria-mediated apoptosis in HepG2 and HT1080 cells. Hence, careful attention is required for human health assessment following combined exposure to nSiO₂ and As.

Mechanism of cell death induced by silica nanoparticles in hepatocyte cells is by apoptosis

Silicon is one of the most widely used chemical materials, and the increasing use of silica nanoparticles (SNs) highlights the requirement for safety and biological toxicity studies. The damaging and adverse effects of SNs on human hepatocytes remain largely unknown, as do the mechanisms involved. In the present study, the mechanisms underlying SN‑induced toxicity in the human hepatocyte cell line HL‑7702 were investigated. An MTT assay revealed that following exposure to SNs in the concentration range of 25‑200 µg/ml, the viability of HL‑7702 cells decreased, and the viability decreased further with increasing exposure time. SNs induced a delay in the S and G2/M phases of the cell cycle, and also induced DNA damage in these cells. Western blot and flow cytometry analyses revealed that cell death was mediated by mitochondrial damage and the upregulated expression of a number of pro‑apoptotic proteins. In conclusion, exposure to SNs led to mitochondrial and DNA damage, resulting in apoptosis‑mediated HL‑7702 cell death. The study provided evidence for the cellular toxicity of SNs, and added to the growing body of evidence regarding the potential damaging effects of nanoparticles, indicating that caution should be exercised in their widespread usage.

Genotoxicity of amorphous silica nanoparticles: Status and prospects

Amorphous silica nanoparticles (SNPs) are widely used in biomedical applications and consumer products. Little is known, however, about their genotoxicity and potential to induce gene expression regulation. Despite recent efforts to study the underlying mechanisms of genotoxicity of SNPs, inconsistent results create a challenge. A variety of factors determine particle-cell interactions and underlying mechanisms. Further, high-throughput studies are required to carefully assess the impact of silica nanoparticle physicochemical properties on induction of genotoxic response in different cell lines and animal models. In this article, we review the strategies available for evaluation of genotoxicity of nanoparticles (NPs), survey current status of silica nanoparticle gene alteration and genotoxicity, discuss particle-mediated inflammation as a contributing factor to genotoxicity, identify existing gaps and suggest future directions for this research.

Cardiac and pulmonary toxicity of mesoporous silica nanoparticles is associated with excessive ROS production and redox imbalance in Wistar rats

Mesoporous silica nanoparticles (MSNs) represent one of the most promising drug delivery systems. MSNs have attracted considerable attention in recent years both in industry and biomedicine due to their unique properties. Thus, evaluation of the toxic effects of MSNs is necessary before the biomedical and clinical applications. We investigated the in vivo effect of MSNs on the production of reactive oxygen species (ROS), antioxidant defenses and histology of the heart and lung. Rats received 25, 50, 100 and 200 mg/kg body weight of synthesized MSNs intraperitoneally for 30 days and samples were collected for analysis. MSNs induced significant increase in serum cardiac function markers, tumor necrosis factor alpha and lipids. MSNs-induced rats exhibited anemia, thrombocytopenia, leukocytosis, significantly increased ROS, malondialdehyde and nitric oxide, and declined antioxidant defenses in the heart and lung of rats. In addition, MSNs induced histological alterations in the heart and lung of rats. In conclusion, our results demonstrated that MSNs induce cardiotoxicity and pulmonary toxicity via excessive generation of ROS, suppressed antioxidants, inflammation and histological alterations. Further investigations are recommended to understand the molecular mechanism underlying the toxic effects of MSNs and to improve the performance of nanomedicine.

Effect of nano-sized SiO2 particles on the cognitive function and biochemical response

Several in vitro studies have convincingly demonstrated that SiO₂NPs mediated cytotoxicity, which was dose-, time- and size-dependent. The data on in vivo toxicity of SiO₂NPs are even more contradictory. In the present study, we investigated the effects of sub-acute exposure to SiO₂-NPs on spatial learning and memory, the biochemical parameters and the histology of organs. Rats were injected intravenously with a single dose of SiO₂-NPs (20 mg/kg) during five consecutive days. The analysis of spatial memory in the Morris water maze showed that SiO₂-NPs disrupt the cognitive abilities of rats. Moreover, SiO₂-NPs could changes the blood counts. However, biochemical markers remained unchanged. Histological examination showed that SiO₂-NPs induced pathological changes in rat organs. In this finding NPs were shown to cause granuloma formation and inflammatory cells infiltration in the liver.

Co-exposure to silver nanoparticles and cadmium induce metabolic adaptation in HepG2 cells

Although multiple studies have reported the toxicological effects and underlying mechanisms of toxicity of silver nanoparticles (AgNP) in a variety of organisms, the interactions of AgNP with environmental contaminants such as cadmium are poorly understood. We used biochemical assays and mass spectrometry-based proteomics to assess the cellular and molecular effects induced by a co-exposure of HepG2 cells to AgNP and cadmium. Cell viability and energy homeostasis were slightly affected after a 4-h exposure to AgNP, cadmium, or a combination of the two; these endpoints were substantially altered after a 24-h co-exposure to AgNP and cadmium, while exposure to one of the two contaminants led only to minor changes. Proteomics analysis followed the same trend: while a 4-h exposure induced minor protein deregulation, a 24-h exposure to a combination of AgNP and cadmium deregulated 43% of the proteome. The toxicity induced by a combined exposure to AgNP and cadmium involved (1) inactivation of Nrf2, resulting in downregulation of antioxidant defense and proteasome-related proteins, (2) metabolic adaptation and ADP/ATP imbalance, and (3) increased protein synthesis possibly to reestablish homeostasis. The adaptation strategy was not sufficient to restore ADP/ATP homeostasis and to avoid cell death.

Halloysite nanotubes-induced Al accumulation and oxidative damage in liver of mice after 30-day repeated oral administration

Halloysite (Al₂ Si₂ O₅ (OH)₄ ·nH₂ O) nanotubes (HNTs) are natural clay materials and widely applied in many fields due to their natural hollow tubular structures. Many in vitro studies indicate that HNTs exhibit a high level of biocompatibility, however the in vivo toxicity of HNTs remains unclear. The objective of this study was to assess the hepatic toxicity of the purified HNTs in mice via oral route. The purified HNTs were orally administered to mice at 5, 50, and 300 mg/kg body weight (BW) every day for 30 days. Oral administration of HNTs stimulated the growth of the mice at the low dose (5 mg/kg BW) with no liver toxicity, but inhibited the growth of the mice at the middle (50 mg/kg BW) and high (300 mg/kg BW) doses. In addition, oral administration of HNTs at the high dose caused Al accumulation in the liver but had no marked effect on the Si content in the organ. The Al accumulation caused significant oxidative stress in the liver, which induced hepatic dysfunction and histopathologic changes. These findings demonstrated that Al accumulation-induced oxidative stress played an important role in the oral HNTs-caused liver injury.

Regulatory role of miR-18a to CCN2 by TGF-β1 signaling pathway in pulmonary injury induced by nano-SiO2

This research is designed to investigate the regulatory effect of miR-18a to the target gene connective tissue growth factor (CTGF, or CCN2), by participating in TGF-β1 signaling pathway and explore the pathogenic mechanism of miR-18a in pulmonary injury induced by nano-SiO₂ based on our early study. miR-18a and expression of TGF-β1 in Chinese hamster lung (CHL) fibroblasts cells stimulated by supernatants of NR8383 cells exposed to 40 μg/ml nano-SiO₂ for 24 h demonstrated 1.58 ± 0.22-fold and 1096.00 ± 2.60 pg/ml increase compared with blank control group analyzed by real-time quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Expression increase of miR-18a and reduction of CCN2 mRNA expression levels and protein gray value ratio detected by Western blotting in CHL cells transfect miR-18a mimics for 48 h. The reverse of CHL cell transfection miR-18a inhibit is also true. The result of miR-18a and CCN2 binding sites tested by luciferase reporter gene assay shows that the report relative fluorescence value of miR-18a mimics wild type on CCN2 is 0.50 ± 0.02 with the control of mimics NC and mutant relative fluorescence report value 0.86 ± 0.04 (P < 0.05). Expression levels of miR-18a, CCN2 mRNA, and protein gray value ratio decreased in CHL cells treated by TGF-β1, respectively, and vice versa treated by TGF-β1corepressor. The results suggest that CCN2 is the target gene regulated by miR-18a and miR-18a participates in TGF-β1 signaling pathway by regulating the expression of CCN2 negatively through CCN2 3'UTR site, and thus may be involved in the development process of pulmonary injury.

Low-dose combined exposure of nanoparticles and heavy metal compared with PM2.5 in human myocardial AC16 cells

The co-exposure toxicity mechanism of ultrafine particles and pollutants on human cardiovascular system are still unclear. In this study, the combined effects of silica nanoparticles (SiNPs) and/or carbon black nanoparticles (CBNPs) with Pb(AC)₂ compared with particulate matter (PM)_2.5 were investigated in human myocardial cells (AC16). Our study detected three different combinations of SiNPs and Pb(AC)₂, CBNPs and Pb(AC)₂, and SiNPs and CBNPs compared with PM_2.5 at low-dose exposure. Using PM_2.5 as positive control, our results suggested that the combination of SiNPs and Pb(AC)₂/CBNPs could increase the production of reactive oxygen species (ROS), lactate dehydrogenase leakage (LDH), and malondialdehyde (MDA) and decrease the activities of superoxide dismutase (SOD) and glutathione (GSH); induce inflammation by the upregulation of protein CRP and TNF-α, and apoptosis by the upregulation of protein caspase-3, caspase-9, and Bax while the downregulation of protein Bcl-2; and trigger G2/M phase arrest by the upregulation of protein Chk2 and downregulation of protein Cdc2 and cyclin B1. In addition, the combination of CBNPs and Pb(AC)₂ induced a significant increase in MDA and reduced the activities of ROS, LDH, SOD, and GSH, with G1/S phase arrest via upregulation of Chk1 and downregulation of CDK6 and cyclin D1. Our data suggested that the additive interaction and synergistic interaction are the major interaction in co-exposure system, and PM_2.5 could trigger more severe oxidative stress, G2/M arrest, and apoptosis than either co-exposure or single exposure.

Differential proteomics highlights macrophage-specific responses to amorphous silica nanoparticles

The technological and economic benefits of engineered nanomaterials may be offset by their adverse effects on living organisms. One of the highly produced nanomaterials under such scrutiny is amorphous silica nanoparticles, which are known to have an appreciable, although reversible, inflammatory potential. This is due to their selective toxicity toward macrophages, and it is thus important to study the cellular responses of this cell type to silica nanoparticles to better understand the direct or indirect adverse effects of nanosilica. We have here studied the responses of the RAW264.7 murine macrophage cells and of the control MPC11 plasma cells to subtoxic concentrations of nanosilica, using a combination of proteomic and targeted approaches. This allowed us to document alterations in the cellular cytoskeleton, in the phagocytic capacity of the cells as well as their ability to respond to bacterial stimuli. More surprisingly, silica nanoparticles also induce a greater sensitivity of macrophages to DNA alkylating agents, such as styrene oxide, even at doses which do not induce any appreciable cell death.

Biosafety study and mechanism comparison on two types of silica with different nanostructures

Silica is frequently used in oral drug delivery; however, its biosafety, particularly concerned with its nanostructure, has not been comprehensively studied yet. Here, the in vitro and in vivo biosafety of two types of silica (A200, nano-sized or micron-sized agglomerates; S350, micro-sized particles with nanopores) were compared and the possible reasons for the differences were explored. The results indicated that both A200 and S350 could inhibit the growth of Caco-2 cells by inducing apoptosis and changing the cell cycle progression. A200 showed a stronger influence than S350 in most of the in vitro experiments. In the in vivo study in KM mice, both A200 and S350 could change the blood constituents under the tested conditions; A200 also increased the levels of inflammatory factors in plasma and the numbers of CD4+ lymphocyte subsets. No obvious organic damage was observed in either the A200-treated or S350-treated groups. The transport study showed that neither A200 nor S350 were readily transported across the intestinal epithelial barrier in vitro and in vivo, but A200 could transport across the lymphatic-associated epithelium and accumulate in the Peyer's Patches, which might explain the A200-induced immune response. The increased transport of A200 might relate to its particle size, dispersion state and specific surface area. In conclusion, these results demonstrated that A200 and S350 exhibited diverse biosafety aspects, which correlated with their different nanostructures. We believe this study will provide some scientific information about the biosafety of A200 and S350 for their applications in oral drug delivery systems.

Silica nanoparticles and lead acetate co-exposure triggered synergistic cytotoxicity in A549 cells through potentiation of mitochondria-dependent apoptosis induction

The adverse effects of PM2.5 are the results of combined toxicities of finer particles and their adsorbed toxic pollutants. Nevertheless, the combined toxicity of finer particles and air pollutants still remains unclear. The present study was therefore undertaken to investigate the combined cytotoxicity of silica nanoparticles (nano-SiO₂, a typical atmospheric ultrafine particle) and lead acetate (Pb, a representative air pollutant) in A549 cells focusing on mitochondria-dependent apoptosis induction. The results showed that Pb exposure alone induced mitochondria-dependent apoptosis in A549 cells, as evidenced by increased apoptotic rate and Bax/Bcl-2 ratio, up-regulated caspases 3 and 9 expressions as well as decreased mitochondrial membrane potential. Non-cytotoxic concentration of nano-SiO₂ exposure alone did not trigger apoptosis in A549 cells, but potentialized the apoptotic changes when co-exposure with Pb. Factorial analyses revealed synergistic interactions were responsible for the potentiation of joint apoptotic responses.

Complex effect of zinc oxide nanoparticles on cadmium chloride-induced hepatotoxicity in mice: protective role of metallothionein

The wide range of applications of ZnO nanoparticles (nano ZnO) in commercial products and the ubiquitous cadmium (Cd) contamination in the natural environment increase the chance of co-existence of nano ZnO with Cd in the surroundings. To investigate the effects of nano ZnO on CdCl₂-induced hepatotoxicity in mice, the histopathologic changes, metallothionein expression, oxidative stress responses and serum biochemical parameters were determined after oral administration of bulk or nano ZnO and/or CdCl₂ for seven consecutive days. Bulk or nano ZnO had low toxicity in mice. In contrast, CdCl₂ led to significant hepatic oxidative damage, as indicated by hepatic histopathological abnormalities and dysfunction. Bulk and nano ZnO had nearly identical influences on the hepatotoxicity of CdCl₂ in mice. Although co-administration of bulk or nano ZnO with CdCl₂ had a positive cooperative effect on the hepatic uptake of Cd and Zn, both bulk and nano ZnO significantly attenuated CdCl₂-caused hepatic damage via the reduction of oxidative stress. The increase in metallothionein synthesis and the reduction of Cd-induced perturbation of Zn²⁺ homeostasis after co-administration of bulk or nano ZnO with CdCl₂ play two important roles in the protective effect of bulk or nano ZnO on CdCl₂-caused hepatic oxidative damage.

Susceptibility of Overweight Mice to Liver Injury as a Result of the ZnO Nanoparticle-Enhanced Liver Deposition of Pb2

The prevalence of the applications of nanomaterials in consumer products and water treatment facilities increases the chance that humans will be exposed to both nanoparticles and environmental pollutants such as heavy metals. Co-exposure to nanoparticles and heavy metals may adversely affect human health, especially in susceptible populations such as overweight subjects. To evaluate the impact of such co-exposures, we orally administered zinc oxide nanoparticles (ZNPs; 14 or 58 nm) and/or Pb(Ac)₂ at tolerable doses to both healthy overweight and healthy normal weight mice. The ZNPs enhanced the deposition of Pb in all major organs in the overweight mice compared with that in the normal mice. As a result, higher levels of hepatic reactive oxygen species, pro-inflammatory cytokines, and liver injury were observed in the overweight mice but not in the normal weight mice. Our findings underscore a potentially enhanced risk of nanoparticle/heavy metal co-exposure in the susceptible overweight population.

Altered microRNA expression profiles in lung damage induced by nanosized SiO2

The objective of the present research is to explore miRNAs expression profiles in lung tissue of rat treated by nanosized SiO₂ in the light of normal at diverse dosages, time, predict their target genes, and probe the biological function and regulation of miRNA in the lung damage process caused by nanosized SiO₂. Up-regulation of rno-miR-208, rno-miR-212 and rno-miR-18a in lung tissue mainly characterized by inflammation of SD rats caused by nanosized SiO₂ particles instilled intratracheally at 7^th, 15^th 30^th d using Illumina HiSeq2000 sequencing technique and were further verified by quantitative reverse transcriptase polymerase chain reaction (qRT PCR) assay. Lung damage is mainly with characteristics of lung interstitial fibrosis, upregulation of rno-miR-212, rno-miR-144, rno-miR-702-3p, rno-miR-379 and rno-miR-127, down-regulation of rno-miR-541 at 60^th, 90^th d post-exposure. As target genes of rno-miR-208, rno-miR-212 and rno-miR-18a respectively, there was no statistical significance of programmed cell death 4 (PDCD4), LIN28B and connective tissue growth factor (CTGF) mRNA expression level (P > 0.05) compared to β-actin as internal controls detected by Real-time quantitative PCR. The differences in protein gray value ratio of PDCD4, LIN28B and CTGF detected by Western blotting test were statistically significant (P < 0.05). These results suggested that miR-208, miR-212 and miR-18a may take effects in rats' lung damage lead by nanosized SiO₂. Their target genes of PDCD4, LIN28B and CTGF functioned in translation level of target genes in regulation of inflammatory signaling pathways and involved in the formation of tissue fibrosis.

Combined toxicity of Fe3O4 nanoparticles and cadmium chloride in mice

Nanomaterials have been widely used in diverse areas. Heavy metals are ubiquitous environmental pollutants. In spite of the real risk of humans' co-exposure to nanoparticles and heavy metals, their combined toxicity has received little attention. We have reported that silica nanoparticles and CdCl2 have a positive synergistic toxicity in mice. Here, we demonstrate that Fe3O4 nanoparticles (nano-Fe3O4) and CdCl2 have a negative synergistic toxicity in mice. Nano-Fe3O4 showed low toxicity in mice. In contrast, CdCl2 caused significant oxidative damage mainly in the liver as indicated by severe liver dysfunction and histopathological abnormalities. Co-exposure to nano-Fe3O4 and CdCl2 significantly attenuated CdCl2-induced damage in the liver through reduction of oxidative stress. Nano-Fe3O4 and CdCl2 had negative cooperative effects on the biodistributions of Fe and Cd in mice due to mutually competitive inhibition of Fe and Cd uptake. The reduction of Cd accumulation in tissues and the inhibition of Cd-induced deprivation of tissue Fe by nano-Fe3O4 played two key roles in the protective effect of nano-Fe3O4 on CdCl2-induced oxidative damage.

Doxorubicin-Functionalized Silica Nanoparticles Incorporated into a Thermoreversible Hydrogel and Intraperitoneally Administered Result in High Prostate Antitumor Activity and Reduced Cardiotoxicity of Doxorubicin

Described here is an anticancer material based on colloidal mesoporous silica nanoparticles (MSNs) functionalized with doxorubicin (DOX), and incorporated into Pluronic F127 hydrogels for prolonged release, with a potential therapeutic application for prostate cancer treatment. The MSNs have spherical morphology, size of about 60 nm, surface area of 970 cm² g^-1 and average pore width of 2.0 nm. A high colloidal stability for the MSNs in the physiological medium used for in vivo administration (NaCl 0.9% w/v) could be attained in the presence of PF127 (from 5 to 18 wt %), where depletion repulsion forces prevent MSN agglomeration. By conjugating DOX, MSN and PF127 (18 wt %) in NaCl 0.9%, the hybrid system has a gelation temperature of 21 °C, which allowed its in vivo administration in the liquid form and further in situ gelation, generating a drug depot system inside the animals after peritoneal injection. The systems were tested in rats with chemically induced prostate cancer and, after this treatment, histopathological analyses confirmed (i) a reduction in the frequency of aggressive tumors; (ii) that the antitumor effect was dependent on MSN concentration; and most importantly (iii) the reduction of DOX intrinsic cardiotoxicity, indicating that the MSNs play a cardioprotective effect.

Endoplasmic reticulum stress eIF2α-ATF4 pathway-mediated cyclooxygenase-2 induction regulates cadmium-induced autophagy in kidney

The heavy metal cadmium (Cd) is nephrotoxic. Recent studies show that autophagy plays an essential role in Cd-induced kidney injury. However, the mechanisms of Cd-induced kidney injury accompanied by autophagy are still obscure. In the present study, we first confirmed that Cd induced kidney damage and dysfunction, along with autophagy, both in vivo and in vitro. Then, we observed that cyclooxygenase-2 (COX-2) and the eIF2α-ATF4 pathway of endoplasmic reticulum (ER) stress were induced by Cd in both kidney tissues and cultured cells. Further studies showed that inhibition of COX-2 with celecoxib or RNA interference (RNAi) inhibited the Cd-induced autophagy in kidney cells. In addition, blocking ER stress with 4-phenylbutyrate or RNAi partially counteracted COX-2 overexpression and autophagy induced by Cd, which suggested that ER stress was required for Cd-induced kidney autophagy. Significantly, our results showed that Cd activated ATF4 and induced its translocation to the nucleus. Knockdown of ATF4 inhibited Cd-induced COX-2 overexpression. While COX-2 overexpression is involved in renal dysfunction, there is no prior report on the role of COX-2 in autophagy regulation. The results of the current study suggest a novel molecular mechanism that the ER stress eIF2α-ATF4 pathway-mediated COX-2 overexpression contributes to Cd-induced kidney autophagy and injury. The present study implies that COX-2 may be a potential target for therapy against Cd-induced nephrotoxicity.

Combined exposure to nano-silica and lead induced potentiation of oxidative stress and DNA damage in human lung epithelial cells

Growing evidence has confirmed that exposure to ambient particulate matters (PM) is associated with increased morbidity and mortality of cardiovascular and pulmonary diseases. Ambient PM is a complex mixture of particles and air pollutants. Harmful effects of PM are specifically associated with ultrafine particles (UFPs) that can adsorb high concentrations of toxic air pollutants and are easily inhaled into the lungs. However, combined effects of UFPs and air pollutants on human health remain unclear. In the present study, we elucidated the combined toxicity of silica nanoparticles (nano-SiO2), a typical UFP, and lead acetate (Pb), a typical air pollutant. Lung adenocarcinoma A549 cells were exposed to nano-SiO2 and Pb alone or their combination, and their combined toxicity was investigated by focusing on cellular oxidative stress and DNA damage. Factorial analyses were performed to determine the potential interactions between nano-SiO2 and Pb. Our results showed that exposure of A549 cells to a modest cytotoxic concentration of Pb alone induced oxidative stress, as evidenced by elevated reactive oxygen species generation and lipid peroxidation, and reduced glutathione content and superoxide dismutase and glutathione peroxidase activities. In addition, exposure of A549 cells to Pb alone induced DNA damage, as evaluated by alkaline comet assay. Exposure of A549 cells to non-cytotoxic concentration of nano-SiO2 did not induce cellular oxidative stress and DNA damage. However, exposure to the combination of nano-SiO2 and Pb potentiated oxidative stress and DNA damage in A549 cells. Factorial analyses indicated that the potentiation of combined toxicity of nano-SiO2 and Pb was induced by additive or synergistic interactions.

Evaluation of zinc-doped magnetite nanoparticle toxicity in the liver and kidney of mice after sub-chronic intragastric administration

Super-paramagnetic iron oxide nanoparticles (SPIONs) have been approved for clinical use due to their salient super-paramagnetic properties and low toxicity. Zn²⁺ doped SPIONs possess significantly higher magnetic susceptibility than that of conventional SPIONs. Here we evaluated the potential toxicity of Zn²⁺ doped Fe₃O₄ nanoparticles (Zn_0.4Fe_2.6O₄ NPs) in the liver and kidney of mice after repeated intragastric administration for 30 days. Zn_0.4Fe_2.6O₄ NPs did not cause significant changes in their body weights and the coefficients of the liver and kidney, but increased the levels of Fe and Zn in the two organs. Zn_0.4Fe_2.6O₄ NP induced slight oxidative stress in the liver and kidney, which could be successfully counteracted by their intrinsic antioxidant systems and had no observable hazardous effects on the histopathology, ultrastructure and functions of the two organs. These results demonstrated that high-performance magnetic Zn_0.4Fe_2.6O₄ NPs did not produce apparent toxicity in the liver and kidney of mice even after sub-chronic intragastric administration. In addition, Zn²⁺ doping not only markedly enhanced magnetic susceptibility of Zn_0.4Fe_2.6O₄ NPs but also significantly increased the stability of Zn_0.4Fe_2.6O₄ NPs in biological conditions, making them appropriate for use in magnetic resonance imaging and drug delivery by the oral route.

Effects of ZnO Nanoparticles on Dimethoate-Induced Toxicity in Mice

The extensive applications of ZnO nanoparticles (nano ZnO) and dimethoate have increased the risk of people's coexposure to nano ZnO and dimethoate. Therefore, we evaluated in this study the effects of nano or bulk ZnO on dimethoate-induced toxicity in mice. The serum biochemical parameters, biodistributions, oxidative stress responses, and histopathological changes in mice were measured after intragastric administration of nano or bulk ZnO and/or dimethoate for 14 days. Oral administration of nano or bulk ZnO at a dose of 50 mg/kg did not cause obvious injury in mice. In contrast, oral administration of dimethoate at a dose of 15 mg/kg induced observable oxidative damage in mice. Co-administration of nano or bulk ZnO with dimethoate significantly increased Zn accumulation by 30.7 ± 1.7% or 29.7 ± 2.4% and dimethoate accumulation by 42.8 ± 2.1% or 46.6 ± 2.9% in the liver, respectively. The increased accumulations of dimethoate and Zn in the liver reduced its cholinesterase activity from 5.64 ± 0.45 U/mg protein to 4.67 ± 0.42 U/mg protein or 4.76 ± 0.45 U/mg protein for nano or bulk ZnO, respectively. Furthermore, the accumulations of dimethoate and Zn in liver also increased hepatic oxidative stress, resulting in severe liver damage. Both nano and bulk ZnO dissolved quickly in acidic gastric fluid, regardless of particle size; therefore, they had nearly identical enhanced effects on dimethoate-induced toxicity in mice.

Nanotoxic profiling of novel iron oxide nanoparticles functionalized with perchloric acid and SiPEG as a radiographic contrast medium

Emerging syntheses and findings of new metallic nanoparticles (MNPs) have become an important aspect in various fields including diagnostic imaging. To date, iodine has been utilized as a radiographic contrast medium. However, the raise concern of iodine threats on iodine-intolerance patient has led to search of new contrast media with lower toxic level. In this animal modeling study, 14 nm iron oxide nanoparticles (IONPs) with silane-polyethylene glycol (SiPEG) and perchloric acid have been assessed for toxicity level as compared to conventional iodine. The nanotoxicity of IONPs was evaluated in liver biochemistry, reactive oxygen species production (ROS), lipid peroxidation mechanism, and ultrastructural evaluation using transmission electron microscope (TEM). The hematological analysis and liver function test (LFT) revealed that most of the liver enzymes were significantly higher in iodine-administered group as compared to those in normal and IONPs groups (P < 0.05). ROS production assay and lipid peroxidation indicator, malondialdehyde (MDA), also showed significant reductions in comparison with iodine group (P < 0.05). TEM evaluation yielded the aberration of nucleus structure of iodine-administered group as compared to those in control and IONPs groups. This study has demonstrated the less toxic properties of IONPs and it may postulate that IONPs are safe to be applied as radiographic contrast medium.

Genotoxicity of synthetic amorphous silica nanoparticles in rats following short-term exposure. Part 1: oral route

Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM-202 and 203) and two precipitated (NM-200 and -201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)-modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose-dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells.

In vivo biodistribution and toxicity of Gd2O3:Eu3+ nanotubes in mice after intraperitoneal injection

To better understand the potential impact of Gd₂O₃:Eu³⁺ nanotubes on human health, we investigated their biodistribution, subacute toxicity, and hepatic injury in mice under different dosages (4.0, 40.0, and 400.0 mg kg⁻¹).

In vivo toxicity of orally administrated silicon dioxide nanoparticles in healthy adult mice

The increasing use of silica nanoparticles (SiNPs) in various applications including industrial, agriculture, and medicine has raised concerns about their potential risks to human health. Various nanotoxicity researches have been done on the assessment of SiNPs' toxic effects; however, a few in vivo investigations exist. In this investigation, an in vivo study was done in order to evaluate the oral toxicity of SiNPs. The biochemical levels of 19 different serum parameters were assessed. Moreover, the histopathological changes have been examined as well. We showed that SiNPs with diameters of 10-15 nm in size can cause significant changes in albumin, cholesterol, triglyceride, total protein, urea, HDL, and LDL as well as in alkaline phosphatase and aspartate aminotransferase activity. In addition, histopathological examinations demonstrated that SiNPs have toxic effects on various tissues including liver, kidney, lung, and testis.

Toxicity of colloidal silica nanoparticles administered orally for 90 days in rats

This study was undertaken to investigate the potential toxicity and establish the no observed adverse effect level (NOAEL) and target organ(s) of negatively charged colloidal silica particles of different sizes, ie, SiO₂^EN20(−) (20 nm) or SiO₂^EN100(−) 2(100 nm), administered by gavage in Sprague-Dawley rats. After verification of the physicochemical properties of the SiO₂ particles to be tested, a preliminary dose range-finding study and 90-day repeated dose study were conducted according to the Organisation for Economic Cooperation and Development test guideline. Based on the results of the 14-day dose range-finding study, a high dose was determined to be 2,000 mg/kg, and middle and low doses were set at 1,000 and 500 mg/kg, respectively. In the 90-day toxicity study, there were no animal deaths in relation to administration of SiO₂ particles of either size. In addition, no treatment-related clinical changes or histopathological findings were observed in any of the experimental groups. Moreover, no difference in toxic effects from chronic exposure to SiO₂^EN20(−)(20 nm) or SiO₂^EN100(−) (100 nm) was observed. The results of this study indicate that the NOAEL for SiO₂^EN20(−) and SiO₂^EN100(−) would most likely be 2,000 mg/kg, and no target organ was identified in rats of either sex.

One-month persistence of inflammation and alteration of fibrotic marker and cytoskeletal proteins in rat kidney after Cd-doped silica nanoparticle instillation

In vivo effects of model cadmium-containing silica nanoparticles (SiNPs-Cd, 1 mg/rat) were investigated by i.t. instillation in rats to evaluate potential effects on secondary target organ, e.g., kidney. Specific endpoints and pathological outcomes were focused to assess inflammation and fibrosis in renal tissue, 7 and 30 days after exposure to SiNPs-Cd, as well as to equivalent amount of CdCl₂ or SiNPs. Immunohistochemistry was employed to investigate the presence/distribution of selected markers, i.e., (i) TGF-ß1, (ii) IL-6 (iii) collagen (type I), (iv) fibronectin, and (v) vimentin. An ongoing inflammatory process was demonstrated, together with a general overexpression of extracellular matrix components and alteration of cytoskeletal proteins, mainly in cortex and medulla, 7 days after SiNPs-Cd, lasting until 30th day. Less pronounced effects were observed after CdCl₂, while SiNPs did not cause any insult except for IL-6 expression increase. Briefly, engineered SiNPs-Cd cause long-lasting injury in rat kidney, following a single pulmonary exposure. Renal response may be due to (i) translocation, i.e., nanoparticles migration from lung to systemic circulation, or (ii) secondary organ changes, caused by circulating inflammatory factors (e.g., IL-6, TGF-ß1) released from lung following local insult, or (iii) direct renal action of cadmium ions released from the absorbed SiNPs-Cd.