Apoptosis induction by silica nanoparticles mediated through reactive oxygen species in human liver cell line HepG2

Impact of Respiratory Dust on Health: A Comparison Based on the Toxicity of PM2.5, Silica, and Nanosilica

Respiratory dust of different particle sizes in the environment causes diverse health effects when entering the human body and makes acute or chronic damage through multiple systems and organs. However, the precise toxic effects and potential mechanisms induced by dust of different particle sizes have not been systematically summarized. In this study, we described the sources and characteristics of three different particle sizes of dust: PM2.5 (<2.5 μm), silica (<5 μm), and nanosilica (<100 nm). Based on their respective characteristics, we further explored the main toxicity induced by silica, PM2.5, and nanosilica in vivo and in vitro. Furthermore, we evaluated the health implications of respiratory dust on the human body, and especially proposed potential synergistic effects, considering current studies. In summary, this review summarized the health hazards and toxic mechanisms associated with respiratory dust of different particle sizes. It could provide new insights for investigating the synergistic effects of co-exposure to respiratory dust of different particle sizes in mixed environments.

Molecular mechanism of nanomaterials induced liver injury: A review

The unique physicochemical properties inherent to nanoscale materials have unveiled numerous potential applications, spanning beyond the pharmaceutical and medical sectors into various consumer industries like food and cosmetics. Consequently, humans encounter nanomaterials through diverse exposure routes, giving rise to potential health considerations. Noteworthy among these materials are silica and specific metallic nanoparticles, extensively utilized in consumer products, which have garnered substantial attention due to their propensity to accumulate and induce adverse effects in the liver. This review paper aims to provide an exhaustive examination of the molecular mechanisms underpinning nanomaterial-induced hepatotoxicity, drawing insights from both in vitro and in vivo studies. Primarily, the most frequently observed manifestations of toxicity following the exposure of cells or animal models to various nanomaterials involve the initiation of oxidative stress and inflammation. Additionally, we delve into the existing in vitro models employed for evaluating the hepatotoxic effects of nanomaterials, emphasizing the persistent endeavors to advance and bolster the reliability of these models for nanotoxicology research.

Lipidomics Investigation Reveals the Reversibility of Hepatic Injury by Silica Nanoparticles in Rats After a 6-Week Recovery Duration

Given the inevitable human exposure owing to its increasing production and utilization, the comprehensive safety evaluation of silica nanoparticles (SiNPs) has sparked concerns. Substantial evidence indicated liver damage by inhaled SiNPs. Notwithstanding, few reports focused on the persistence or reversibility of hepatic injuries, and the intricate molecular mechanisms involved remain limited. Here, rats are intratracheally instilled with SiNPs in two regimens (a 3-month exposure and a subsequent 6-week recovery after terminating SiNPs administration) to assess the hepatic effects. Nontargeted lipidomics revealed alterations in lipid metabolites as a contributor to the hepatic response and recovery effects of SiNPs. In line with the functional analysis of differential lipid metabolites, SiNPs activated oxidative stress, and induced lipid peroxidation and lipid deposition in the liver, as evidenced by the elevated hepatic levels of ROS, MDA, TC, and TG. Of note, these indicators showed great improvements after a 6-week recovery, even returning to the control levels. According to the correlation, ROC curve, and SEM analysis, 11 lipids identified as potential regulatory molecules for ameliorating liver injury by SiNPs. Collectively, the work first revealed the reversibility of SiNP-elicited hepatotoxicity from the perspective of lipidomics and offered valuable laboratory evidence and therapeutic strategy to facilitate nanosafety.

Local and systemic adverse effects of nanoparticles incorporated in dental materials- a critical review

Introduction

Nanotechnology is the science and engineering of nanoparticles whose dimensions range from 1 to 100 nm. Nanoparticles have special characteristics like increased surface area, high reactivity, and enhanced mechanical, thermal, and optical properties that make them attractive for use in dental applications. However, the use of nanoparticles in dental materials can have toxic effects on the human body. The objective of this paper is to discuss the toxic effects of various nanoparticles in dental materials, their adverse effect on human health, and measures to overcome such effects.

Objectives

Nanoparticles are used in the diagnosis, prevention, and treatment of oral diseases like dental caries, pulpo periodontal lesions, oral cancer, denture stomatitis, and candidiasis. Exposure to nanoparticles may occur to the dental professional, and the patient during procedures like restoration, finishing, and polishing. Such exposure to nanoparticles through inhalation, and ingestion causes toxic effects in the lungs, skin, brain, liver, and kidney. Proper risk assessment methods and preventive measures may help reduce these toxic effects to some extent.

Significance

Toxic effects of nanoparticles that are released during dental procedures, their route of exposure, and the concentration at which nanoparticles can induce toxic effects on the human body are discussed in detail in this review. The paper also aims to create awareness among dental professionals, students, and patients regarding nanoparticle exposure and its adverse effects, and methods to prevent and overcome these effects. Currently, it is ignored or taken lightly by the stakeholders and this review may throw light.

Prospects and hazards of silica nanoparticles: Biological impacts and implicated mechanisms

With the thrive of nanotechnology, silica nanoparticles (SiNPs) have been extensively adopted in the agriculture, food, cosmetic, and even biomedical industries. Due to the mass production and use, SiNPs inevitably entered the environment, resulting in ecological toxicity and even posing a threat to human health. Although considerable investigations have been conducted to assess the toxicity of SiNPs, the correlation between SiNPs exposure and consequent health risks remains ambiguous. Since the biological impacts of SiNPs can differ from their design and application, the toxicity assessment for SiNPs may be extremely difficult. This review discussed the application of SiNPs in different fields, especially their biomedical use, and documented their potential release pathways into the environment. Meanwhile, the current process of assessing SiNPs-related toxicity on various model organisms and cell lines was also detailed, thus estimating the health threats posed by SiNPs exposure. Finally, the potential toxic mechanisms of SiNPs were also elaborated based on results obtained from both in vivo and in vitro trials. This review generally summarizes the biological effects of SiNPs, which will build up a comprehensive perspective of the application and toxicity of SiNPs.

Silicon dioxide nanoparticles adsorption alters the secondary and tertiary structures of catalase and undermines its activity

The expanding production and use of nanomaterials in various fields caused big concern for human health. Oxidative stress is the most frequently described mechanism of nanomaterial toxicity. A state of oxidative stress can be defined as the imbalance of reactive oxygen species (ROS) production and antioxidant enzyme activities. Although nanomaterials-triggered ROS generation has been extensively investigated, little is known regarding the regulation of antioxidant enzyme activities by nanomaterials. This study used two typical nanomaterials, SiO₂ nanoparticles (NPs) and TiO₂ NPs, to predict their binding affinities and interactions with antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). The molecular docking results showed that CAT and SOD had different binding sites, binding affinity, and interaction modes with SiO₂ NPs and TiO₂ NPs. The binding affinities of the two NPs to CAT were more potent than those to SOD. Consistently, the experimental work indicated NPs adsorption caused the perturbation of the second and tertiary structures of both enzymes and thus resulted in the loss of enzyme activities.

Magnesium Supplementation Alleviates the Toxic Effects of Silica Nanoparticles on the Kidneys, Liver, and Adrenal Glands in Rats

Concerns regarding the possible hazards to human health have been raised by the growing usage of silica nanoparticles (SiNPs) in a variety of applications, including industrial, agricultural, and medical applications. This in vivo subchronic study was conducted to assess the following: (1) the toxicity of orally administered SiNPs on the liver, kidneys, and adrenal glands; (2) the relationship between SiNPs exposure and oxidative stress; and (3) the role of magnesium in mitigating these toxic effects. A total of 24 Sprague Dawley male adult rats were divided equally into four groups, as follows: control group, magnesium (Mg) group (50 mg/kg/d), SiNPs group (100 mg/kg/d), and SiNPs+ Mg group. Rats were treated with SiNPs by oral gavage for 90 days. The liver transaminases, serum creatinine, and cortisol levels were evaluated. The tissue malondialdehyde (MDA) and reduced glutathione (GSH) levels were measured. Additionally, the weight of the organs and the histopathological changes were examined. Our results demonstrated that SiNPs exposure caused increased weight in the kidneys and adrenal glands. Exposure to SiNPs was also associated with significant alterations in liver transaminases, serum creatinine, cortisol, MDA, and GSH. Additionally, histopathological changes were significantly reported in the liver, kidneys, and adrenal glands of SiNPs-treated rats. Notably, when we compared the control group with the treated groups with SiNPs and Mg, the results revealed that magnesium could mitigate SiNPs-induced biochemical and histopathologic changes, confirming its effective role as an antioxidant that reduced the accumulation of SiNPs in tissues, and that it returns the levels of liver transaminases, serum creatinine, cortisol, MDA, and GSH to almost normal values.

Influences of l-ascorbic acid on cytotoxic, biochemical, and genotoxic damages caused by copper II oxide nanoparticles in the rainbow trout gonad cells-2

In parallel with the raising use of copper oxide nanoparticles (CuO NPs) in various industrial and commercial practices, scientific reports on their release to the environment and toxicity are increasing. The toxicity of CuO NPs is mostly based on their oxidative stress. Therefore, it is necessary to investigate the efficacy of well-known therapeutic agents as antioxidants against CuO NPs damage. This study aimed to investigate the mechanism of this damage and to display whether l-ascorbic acid could preserve against the cell toxicities induced by CuO NPs in the rainbow trout gonad cells-2 (RTG-2). While CuO NPs treatment significantly diminished cell viability, the l-ascorbic acid supplement reversed this. l-ascorbic acid treatment reversed the changes in expressions of sod1, sod2, gpx1a, and gpx4b genes while playing a supportive role in the changes in the expression of the cat gene induced by CuO NPs treatment. Moreover, CuO NPs treatment caused an upregulation in the expressions of growth-related genes (gh1, igf1, and igf2) and l-ascorbic acid treatment further increased these effects. CuO NPs treatment significantly up-regulated the expression of the gapdh gene (glycolytic enzyme gene) compared to the control group, and l-ascorbic acid treatment significantly down-regulated the expression of the gapdh gene compared to CuO NPs treatment. The genotoxicity test demonstrated that l-ascorbic acid treatment increased the genotoxic effect caused by CuO NPs by acting as a co-mutagen. Based on the findings, l-ascorbic acid has the potential to be sometimes inhibitory and sometimes supportive of cellular mechanisms caused by CuO NPs.

Silica Nanoparticles Promote Apoptosis in Ovarian Granulosa Cells via Autophagy Dysfunction

Although silica nanoparticles (SNPs) are generally thought to be biocompatible and safe, the adverse effects of SNPs were also reported in previous studies. SNPs cause follicular atresia via the induction of ovarian granulosa cell apoptosis. However, the mechanisms for this phenomenon are not well understood. This study focuses on exploring the relationship between autophagy and apoptosis induced by SNPs in ovarian granulosa cells. Our results showed that 25.0 mg/kg body weight (b.w.)/intratracheal instillation of 110 nm in diameter spherical Stöber SNPs caused ovarian granulosa cell apoptosis in follicles in vivo. We also found that SNPs mainly internalized into the lumens of the lysosomes in primary cultured ovarian granulosa cells in vitro. SNPs induced cytotoxicity via a decrease in viability and an increase in apoptosis in a dose-dependent manner. SNPs increased BECLIN-1 and LC3-II levels, leading to the activation of autophagy and increased P62 level, resulting in the blockage of autophagic flux. SNPs increased the BAX/BCL-2 ratio and cleaved the caspase-3 level, resulting in the activation of the mitochondrial-mediated caspase-dependent apoptotic signaling pathway. SNPs enlarged the LysoTracker Red-positive compartments, decreased the CTSD level, and increased the acidity of lysosomes, leading to lysosomal impairment. Our results reveal that SNPs cause autophagy dysfunction via lysosomal impairment, resulting in follicular atresia via the enhancement of apoptosis in ovarian granulosa cells.

Adverse effects and underlying mechanism of amorphous silica nanoparticles in liver

Amorphous silica nanoparticles (SiNPs) have been widely used and mass-producted due to its unique properties. With the life cycle of SiNPs-based products, SiNPs are further released into the air, soil, surface water and sediment, resulting in an increasing risk to humans. SiNPs could enter into the human body through vein, respiratory tract, digestive tract or skin. Moreover, recent evidences have showed that, regardless of exposure pathways, SiNPs could even be traced in liver, which is gradually considered as one of the main organs that SiNPs accumulate. Increasing evidences supported the link between SiNPs exposure and adverse liver effects. However, the research models are diverse and the molecular mechanisms have not been well integrated. In this review, the liver-related studies of SiNPs in vivo and in vitro were screened from the PubMed database by systematic retrieval method. We explored the interaction between SiNPs and the liver, and especially proposed a framework of SiNPs-caused liver toxicity, considering AOP Wiki and existing studies. We identified increased reactive oxygen species (ROS) as a molecular initiating event (MIE), oxidative stress, endoplasmic reticulum stress, lysosome disruption and mitochondrial dysfunction as subsequent key events (KEs), which gradually led to adverse outcomes (AOs) containing liver dysfunction and liver fibrosis through a series of key events about cell inflammation and death such as hepatocyte apoptosis/pyroptosis, hepatocyte autophagy dysfuncton and hepatic macrophages pyroptosis. To our best knowledge, this is the first AOP proposed on SiNPs-related liver toxicity. In the future, more epidemiological studies need to be performed and more biomarkers need to be explored to improve the AOP framework for SiNPs-associated liver toxicity.

Mesoporous silica nanoparticles incorporated with Ir(III) complexes: From photophysics to photodynamic therapy

Organically modified mesoporous silica nanoparticles (MSNs) containing Ir complexes (Ir1, Ir2 and Ir3) were successfully synthesized. These Ir-entrapped MCM41-COOH nanoparticles have shown relevant photophysical characteristics including high efficiency in the photoproduction and delivery of singlet oxygen (¹O₂), which is particularly promising for photodynamic therapy (PDT) applications. In vitro tests have evidenced that complex@MCM41-COOH are able to reduce cell proliferation after 10 min of blue-light irradiation in Hep-G2 liver cancer cells.

Design of functionalized magnetic silica multi-core composite nanoparticles for synergistic magnetic hyperthermia/radiotherapy in cancer cells

Nanomaterials in particular the magnetic nanoparticles (MNPs) offer tremendous potential for cancer treatment due to their unique intrinsic properties. Combining materials with a variety of functional groups, and forming a multifunctional nanosystem to overcome the limitations of monotherapy for cancer treatment has always been a research focus with notable difficulties. Considering the many challenges faced by radiotherapy and hyperthermia, in this study, we designed a rational strategy for magnetic hyperthermia using Fe3O4@SiO2@Sec2@FA nanoparticles as a novel nano-radiosensitizer to simultaneously enhance the therapeutic effects of radiotherapy in the future. Fe3O4@SiO2 core-shell structured nanoparticles were synthesized with an appropriate silica layer thickness to maintain good saturation magnetization. The as-prepared Fe3O4@SiO2@Sec2@FA nanoparticles had the specific absorption rate (SAR)value of 57 W/g, which was below the clinically acceptable alternating magnetic field value of 4.9 × 109 Am-1s-1, indicating good heat generation efficiency (the temperature level ΔT=6-10 °C). Moreover, Folate-modified nanoparticles exhibited approximately 6-fold higher cellular internalization of Hela cells with no obvious cytotoxicity for the Hela and MDA-MB-231 cells, and lower cytotoxicity for the HUVECs in a concentration range of 0-150 µg/mL. In addition, these nanoparticles were modified on the silica surface by L-selenocystine, which could enhance the elimination of tumor cells by producing reactive oxygen species under X-rays, resulting in a novel radiosensitization effect. Therefore, the as-prepared Fe3O4@SiO2@Sec2@FA nanoparticles with good biocompatibility and active targeting would possess synergistic magnetic hyperthermia/radiotherapy effect.

Dietary Antioxidant Curcumin Mitigates CuO Nanoparticle-Induced Cytotoxicity through the Oxidative Stress Pathway in Human Placental Cells

The placenta is an important organ that maintains a healthy pregnancy by transporting nutrients to the fetus and removing waste from the fetus. It also acts as a barrier to protect the fetus from hazardous materials. Recent studies have indicated that nanoparticles (NPs) can cross the placental barrier and pose a health risk to the developing fetus. The high production and widespread application of copper oxide (CuO) NPs may lead to higher exposure to humans, raising concerns of health hazards, especially in vulnerable life stages, e.g., pregnancy. Oxidative stress plays a crucial role in the pathogenesis of adverse pregnancy outcomes. Due to its strong antioxidant activity, dietary curcumin can act as a therapeutic agent for adverse pregnancy. There is limited knowledge on the hazardous effects of CuO NPs during pregnancy and their mitigation by curcumin. This study aimed to investigate the preventive effect of curcumin against CuO NP-induced toxicity in human placental (BeWo) cells. CuO NPs were synthesized by a facile hydrothermal process and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence techniques. We observed that curcumin did not induce toxicity in BeWo cells (1-100 µg/mL for 24 h), whereas CuO NPs decreased the cell viability dose-dependently (5-200 µg/mL for 24 h). Interestingly, CuO NP-induced cytotoxicity was effectively mitigated by curcumin co-exposure. The apoptosis data also exhibited that CuO NPs modulate the expression of several genes (p53, bax, bcl-2, casp3, and casp9), the activity of enzymes (caspase-3 and -9), and mitochondrial membrane potential loss, which was successfully reverted by co-treatment with curcumin. The mechanistic study suggested that CuO-induced reactive oxygen species generation, lipid peroxidation, and higher levels of hydrogen peroxide were significantly alleviated by curcumin co-exposure. Moreover, glutathione depletion and the lower activity of antioxidant enzymes (superoxide dismutase, glutathione peroxidase, and catalase) were effectively mitigated by curcumin. We believe this is the first report exhibiting that CuO-induced toxicity in BeWo cells can be effectively alleviated by curcumin. The pharmacological potential of dietary curcumin in NP-induced toxicity during pregnancy warrants further investigation.

Synthesis and Biological Evaluation of Indole-2-Carboxamides with Potent Apoptotic Antiproliferative Activity as EGFR/CDK2 Dual Inhibitors

The apoptotic antiproliferative actions of our previously reported CB1 allosteric modulators 5-chlorobenzofuran-2-carboxamide derivatives VIIa–j prompted us to develop and synthesise a novel series of indole-2-carboxamide derivatives 5a–k, 6a–c, and 7. Different spectroscopic methods of analysis were used to validate the novel compounds. Using the MTT assay method, the novel compounds were examined for antiproliferative activity against four distinct cancer cell lines. Compounds 5a–k, 6a–c, and 7 demonstrated greater antiproliferative activity against the breast cancer cell line (MCF-7) than other tested cancer cell lines, and 5a–k (which contain the phenethyl moiety in their backbone structure) demonstrated greater potency than 6a–c and 7, indicating the importance of the phenethyl moiety for antiproliferative action. Compared to reference doxorubicin (GI₅₀ = 1.10 µM), compounds 5d, 5e, 5h, 5i, 5j, and 5k were the most effective of the synthesised derivatives, with GI₅₀ ranging from 0.95 µM to 1.50 µM. Compounds 5d, 5e, 5h, 5i, 5j, and 5k were tested for their inhibitory impact on EGFR and CDK2, and the results indicated that the compounds tested had strong antiproliferative activity and are effective at suppressing both CDK2 and EGFR. Moreover, the studied compounds induced apoptosis with high potency, as evidenced by their effects on apoptotic markers such as Caspases 3, 8, 9, Cytochrome C, Bax, Bcl2, and p53.

Silica nanoparticles: Biomedical applications and toxicity

Silica nanoparticles (SiNPs) are composed of silicon dioxide, the most abundant compound on Earth, and are used widely in many applications including the food industry, synthetic processes, medical diagnosis, and drug delivery due to their controllable particle size, large surface area, and great biocompatibility. Building on basic synthetic methods, convenient and economical strategies have been developed for the synthesis of SiNPs. Numerous studies have assessed the biomedical applications of SiNPs, including the surface and structural modification of SiNPs to target various cancers and diagnose diseases. However, studies on the in vitro and in vivo toxicity of SiNPs remain in the exploratory stage, and the toxicity mechanisms of SiNPs are poorly understood. This review covers recent studies on the biomedical applications of SiNPs, including their uses in drug delivery systems to diagnose and treat various diseases in the human body. SiNP toxicity is discussed in terms of the different systems of the human body and the individual organs in those systems. This comprehensive review includes both fundamental discoveries and exploratory progress in SiNP research that may lead to practical developments in the future.

Nonselective Cell Necrosis Mediated by the Total Flavones of Penthorum Chinensis Pursh and Thonningianin-A in Human Hepatic and Hepatoma Cells

Penthorum chinensis Pursh (PCP), family Penthoraceae, has been used for hundreds of years in China. With the launch of PCP tablets, clinical applications focused on liver fibrosis and hepatocarcinoma. The purpose of this research was to explore the selectivity and toxicity of the active pharmacodynamic ingredients of PCP in vitro. The total flavones of PCP (TFPCE) and thonningianin-A (Th-A), a major flavone in TFPCE, were investigated on the cell death patterns in human hepatoma cells (HepG2) and human hepatic cells (LO2), followed by a concentration detection of LDH in the supernatants. Apoptosis and necrosis detection kits were used to validate the patterns of cell death caused by TFPCE and Th-A. Finally, the cytotoxicity of both TFPCE and Th-A were reproduced in the colorectal adenocarcinoma cells (NCI-H716). The results indicated that TFPCE inhibits the cell viability of HepG2 cells at a concentration lower than 25 μg/mL. Alternatively, the cell viability of LO2 cells dramatically decreased in the treatment of TFPCE at 25 μg/mL. The effects of Th-A on the cell viability of HepG2 cells and LO2 cells were consistent with TFPCE. LDH detection indicated that TFPCE and Th-A increased the LDH concentration of the supernatants in a dose-dependent way, indicating the pattern of cell necrosis. Fluorescence staining verified the necrosis cell death caused by TFPCE and Th-A. A dose-dependent tendency was obtained in NCI-H716 cells, indicating that the cell viability of NCI-H716 cells was significantly suppressed with the treatment of TFPCE and Th-A. Our results bring the potential toxicity of PCP to the forefront of public attention. Therefore, the clinical application of P chinensis is required to focus more on its cytotoxic effect.

The Yin and Yang of epigenetics in the field of nanoparticles

Nanoparticles (NPs) have become a very exciting research avenue, with multitudinous applications in various fields, including the biomedical one, whereby they have been gaining considerable interest as drug carriers able to increase bioavailability, therapeutic efficiency and specificity of drugs. Epigenetics, a complex network of molecular mechanisms involved in gene expression regulation, play a key role in mediating the effect of environmental factors on organisms and in the etiology of several diseases (e.g., cancers, neurological disorders and cardiovascular diseases). For many of these diseases, epigenetic therapies have been proposed, whose application is however limited by the toxicity of epigenetic drugs. In this review, we will analyze two aspects of epigenetics in the field of NPs: the first is the role that epigenetics play in mediating nanotoxicity, and the second is the possibility of using NPs for delivery of "epi-drugs" to overcome their limitations. We aim to stimulate discussion among specialists, specifically on the potential contribution of epigenetics to the field of NPs, and to inspire newcomers to this exciting technology.

In Situ Detection of Nanotoxicity in Living Cells Based on Multiple miRNAs Probed by a Peptide Functionalized Nanoprobe

The potential toxicity of nanoparticles, especially for clinically applicable ones, has become a critical concern. Technologies that can in situ-evaluate the toxicity of nanoparticles with high sensitivity are urgently needed. In this study, a facile strategy was developed for sensitive detection on the nanotoxicity of nanoparticles with low toxicity or a low dose. A functional nanoprobe loaded with molecular beacons was constructed to realize in situ evaluation of the nanotoxicity through probing multiple miRNAs in nanoparticle-exposed living cells. Being composed of protamine complexed with molecular beacons for miRNA detection and decorated by TAT and KALA peptides, the dual-peptide functionalized nanoprobe can efficiently deliver molecular beacons into living cells to realize the real-time monitoring of early biomarkers (miR-21 and miR-221) to evaluate nanotoxicity. Using mesoporous silica nanoparticles (MSNs) with different surface modifications as typical representatives of low toxic nanoparticles, we demonstrate that our nanoprobe can sensitively detect miRNA changes in cells under diverse exposure conditions, that is, MSN-NH₂ exhibits the strongest capability to upregulate miR-21 and miR-221, and the upregulation is exposure dose- and time-dependent. Our approach is much more sensitive as compared with conventional methods to study cytotoxicity such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell morphology observation, and reactive oxygen species (ROS) assay. This study paves a path for effective and facile nanotoxicity evaluation and provides insights into the biological impacts of MSNs.

Hexafluoropropylene oxide dimer acid (GenX) exposure induces apoptosis in HepG2 cells

Hexafluoropropylene oxide dimer acid, also known as GenX, is a poly- and perfluoroalkyl substance (PFAS). PFASs are nonvolatile synthetic substances that can be readily disseminated into the environment during processing and use, making them easy to implement in the soil, drinking water, and air. Compared to other PFASs, GenX has a comparatively short carbon chain length and is expected to have a lower tendency to accumulate in humans; therefore, GenX has recently been used as a substitute to other PFASs. However, the mechanisms underlying GenX action and intoxication in humans remains unclear. In this study, the apoptotic capacity of GenX in human liver cells was investigated. When representative human-derived liver cells (HepG2 cells) were treated with GenX for 12 h, cell viability was reduced, and apoptosis was greatly increased. In addition, GenX increased the generation of intracellular reactive oxygen species (ROS), indicating the induction of oxidative stress in a dose-dependent manner. GenX treatment increased the expression of major apoptosis-related genes relative to the untreated control group. This research indicates that GenX causes apoptosis through ROS mediation in HepG2 cells, which may expand our knowledge of the molecular and toxicological mechanisms of GenX.

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Hexafluoropropylene oxide dimer acid (GenX) can be harmful to the liver.

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Through the mediation of ROS, GenX causes apoptosis in HepG2 cells.

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GenX activates Bax, caspase 3/9, CHOP, and p53 via the apoptosis.

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The intrinsic pathway links GenX mode of action to apoptosis-related stimuli.

Assessment of the Cytotoxic Activity of Triphala: A Semisolid Traditional Formulation on HepG2 Cancer Cell Line

Cancer chemotherapies may result in resistance, and therefore, contemporary treatments including natural products may find an increasing consideration. As per Persian medicine (PM), many natural products have been used for malignant and chronic diseases. Triphala, with a combination of Terminalia chebula Retz., Terminalia bellirica Retz., Phyllanthus emblica L., and honey, is a multi-ingredient traditional formulation attributed to anticancer activities in PM. This study is aimed at evaluating the cytotoxic activity of this preparation on HepG₂, the human liver cancer cell line. Hydroalcoholic extracts were prepared from the formulation and its components. Compared with the control and Cisplatin, the extracts were tested using MTT assay at different concentrations. All concentrations of the preparation, as well as Cisplatin, were effective significantly against HepG₂ cells. All extract preparations at multiple concentrations were significantly effective as evidenced by MTT assay when compared to the control group. The IC₅₀ level for Triphala extract was 77.63 ± 4.3 μg/ml. Based on the results, Triphala and its components have cytotoxic activity on the HepG₂ cancer cell line and they can reduce the survival rate significantly.

Panax ginseng modulates oxidative stress, DNA damage, apoptosis, and inflammations induced by silicon dioxide nanoparticles in rats

Silicon dioxide nanoparticles (SiO₂ NPs) are extensively used in cosmetics, food, and drug delivery. The main mechanism of SiO₂ NPs toxicities depends on oxidative stress. Ginseng (Panax ginseng Meyer) is used in various medicinal applications because of its antioxidant efficiency. Therefore, the present study was carried out to investigate the possible combated role of ginseng against SiO₂ NPs toxicity in rat liver. Thirty-five male rats (160-180 g) were allocated into five groups of seven rats each, randomly. The first group was used as a control while groups 2, 3, 4, and 5 were treated orally with ginseng (Gin; 75 mg/kg, 1/10 LD₅₀ ), SiO₂ NPs, (200 mg/kg, 1/10 LD₅₀ ), Gin + SiO₂ NPs (protection group), and SiO₂ NPs + Gin (therapeutic group) for 5 weeks, respectively. Treatment with SiO₂ NPs increased lipid peroxidation, liver function enzymes, and decreased antioxidant enzymes (SOD, CAT, GPx, GST) activity and non-enzymatic antioxidant (GSH) level. SiO₂ NPs administration motivated liver apoptosis as revealed by the upregulation of the apoptotic genes, Bcl2-associated x protein (Bax), and Beclin 1 and downregulation of the anti-apoptotic gene, B-cell lymphoma 2 (Bcl2) as well as increase in DNA damage. Also, SiO₂ NPs administration caused inflammation as indicated by upregulation of the inflammation-related genes (interleukin 1 beta [IL1β], tumor necrosis factor-alpha [TNFα], nuclear factor kappa B [NFκB], cyclooxygenase 2 [Cox2], transforming growth factor-beta 1 [TGFβ1]) as well as cell cycle arrest in the G0/G1 phase of liver cells. Moreover, histopathological examination proved the biochemical and molecular perturbations occurred due to SiO₂ NPs toxicity. On the other hand, ginseng caused a significant modulation on the deleterious effects induced by SiO₂ NPs in rat liver. In conclusion, ginseng has a potent preventive effect than the therapeutic one and might be used in the treatment of SiO₂ NPs hepatotoxicity.

Pt-Coated Au Nanoparticle Toxicity Is Preferentially Triggered Via Mitochondrial Nitric Oxide/Reactive Oxygen Species in Human Liver Cancer (HepG2) Cells

Reactive nitrogen species (RNS) that are formed from the reaction of versatile nitric oxide (NO) with reactive oxygen species (ROS) have been less explored in potential cancer therapy. This may be partly due to the fewer available agents that could induce NO in cells. Here, we report platinum-coated gold nanoparticles (Pt-coated Au NPs; 27 ± 20 nm) as a strong inducer of NO (assessed by live-cell imaging under NO-specific DAR-1 probe labeling and indirectly using a Griess reagent) in human liver carcinoma (HepG2) cells. In addition to NO, this study found a critical role of ROS from mitochondrial sources in the mechanism of toxicity caused by Pt-coated Au NPs. Cotreatment with a thiol-replenishing general antioxidant NAC (N-acetyl cysteine) led to significant amelioration of oxidative stress against NP-induced toxicity. However, NAC did not exhibit as much ameliorative potential against NP-induced oxidative stress as the superoxide radical (O2•-)-scavenging mitochondrial specific antioxidant mito-TEMPO did. The higher protective potential of mito-TEMPO in comparison to NAC reveals mitochondrial ROS as an active mediator of NP-induced toxicity in HepG2 cells. Moreover, the relatively unaltered NP-induced NO concentration under cotreatment of GSH modulators NAC and buthionine sulfoximine (BSO) suggested that NO production due to NP treatment is rather independent of the cellular thiols at least in HepG2 cells. Moreover, toxicity potentiation by exogenous H2O2 again suggested a more direct involvement of ROS/RNS in comparison to the less potentiation of toxicity due to GSH-exhausting BSO. A steeper amelioration in NP-induced NO and ROS and, consequently, cytotoxicity by mito-TEMPO in comparison to NAC reveal a pronounced role of NO and ROS via the mitochondrial pathway in the toxicity of Pt-coated Au NPs in HepG2 cells.

Behavioural alterations induced by chronic exposure to 10 nm silicon dioxide nanoparticles

Silicon dioxide nanoparticles (SiO2 NPs) are widely invested in medicine, industry, agriculture, consuming products, optical imaging agents, cosmetics, and drug delivery. However, the toxicity of these NPs on human health and the ecosystem have not been extensively studied and little information is available about their behavioural toxicities. The current study aimed to find out the behavioural alterations that might be induced by chronic exposure to 10 nm SiO2 NPs. BALB/C mice were subjected to 36 injections of SiO2 NPs (2 mg/kg Bw) and subjected to 11 neurobehavioural tests: elevated plus-maze test, elevated zero-maze test, multiradial maze test, open field test, hole-board test, light-dark box test, forced swimming test, tail-suspension test, Morris water-maze test, Y-maze test and multiple T-maze test. Treated mice demonstrated anxiety-like effect, depression tendency, behavioural despair stress, exploration and locomotors activity reduction with error induction in both reference and working memories. The findings may suggest that silica NPs are anxiogenic and could aggravate depression affecting memory, learning, overall activity and exploratory behaviour. Moreover, the findings may indicate that these nanomaterials (NMs) may induce potential oxidative stress in the body leading to neurobehavioural alterations with possible changes in the vital organ including the central nervous system.

The Pro-Apoptotic Effect of Silica Nanoparticles Depends on Their Size and Dose, as Well as the Type of Glioblastoma Cells

Despite intensive investigations, nanoparticle-induced cellular damage is an important problem that has not been fully elucidated yet. Here, we report that silica nanoparticles (SiNPs) demonstrated anticancer influence on glioblastoma cells by the induction of apoptosis or necrosis. These effects are highly cell type-specific, as well as dependent on the size and dose of applied nanoparticles. Exposure of LN-18 and LBC3 cells to different sizes of SiNPs-7 nm, 5-15 nm, or 10-20 nm-at dosages, ranging from 12.5 to 1000 µg/mL, for 24 and 48 h reduced the viability of these cells. Treatment of LN-18 and LBC3 cells with 7 nm or 10-20 nm SiNPs at doses ≥50 µg/mL caused a strong induction of apoptosis, which is connected with an increase of intracellular reactive oxygen species (ROS) production. The 5-15 nm SiNPs exhibited distinct behavior comparing to silica nanoparticles of other studied sizes. In contrast to LBC3, in LN-18 cells exposed to 5-15 nm SiNPs we did not observe any effect on apoptosis. These nanoparticles exerted only strong necrosis, which was connected with a reduction in ROS generation. This suggests that SiNPs can trigger different cellular/molecular effects, depending on the exposure conditions, the size and dose of nanoparticles, and cell type of glioblastoma.

In vitro and in vivo uterine metabolic disorders induced by silica nanoparticle through the AMPK signaling pathway

Exposure to silica nanoparticles (SiNPs) has been suggested to cause physical disorders, yet the effects of SiNPs on female reproduction have not been illustrated. This study was implemented to explore the reproductive toxicity of SiNPs on female and reveal its underlying mechanisms. Methodologically, the fluorescein isothiocyanate (FITC)-SiNPs were synthesized by coupling with FITC and then used to track the biodistribution of SiNPs in vitro and in vivo. In total, 30 mice were intratracheally injected 0.25 g of FITC-SiNPs, and 6 mice injected with the same volume of saline were used as controls. The results showed that SiNPs penetrated the cellular membrane, triggering apoptosis and inhibiting proliferation, tube formation, and invasion of trophoblast. Mechanistically, SiNPs was demonstrated to dysregulate Fbp2, Cpt1a, Scd1, and Pfkl, and further induced accumulation of pyruvate and fatty acid in mitochondria through the AMPK signaling pathway, which finally activated the Caspase-3-dependent apoptosis. Consistently, the similar alterations of these genes were detected in vivo, and the uterine inflammatory infiltration aggravated with the extension of the observation duration. These results suggested that SiNPs induced trophoblast apoptosis and uterine inflammation, and ultimately caused acute reproductive toxicity on female. The underlying mechanism might be explained by the dysregulation of Fbp2/Cpt1a/Pfkl/Scd1 axis, which promoted the overload of glucose and lipid through the AMPK signaling pathway. These findings were of great significance to guide a comprehensive understanding of the reproductive toxicity of SiNPs as well as the development of environmental standards.

Ecotoxicity to Freshwater Organisms and Cytotoxicity of Nanomaterials: Are We Generating Sufficient Data for Their Risk Assessment?

The aim of the present study was to investigate the eco-cytotoxicity of several forms of nanomaterials (NM), such as nano-CuO, nano-TiO₂, nano-SiO₂ and nano-ZnO, on different aquatic species (Raphidocelis subcapitata, Daphnia magna and Lemna minor) following standard protocols and on human cell lines (Caco-2, SV-80, HepG2 and HaCaT). Predicted no-effect concentrations (PNEC) or hazard concentrations for 5% of the species (HC₅) were also estimated based on the compilation of data available in the literature. Most of the NM agglomerated strongly in the selected culture media. For the ecotoxicity assays, nano-CuO and nano-ZnO even in particle agglomeration state were the most toxic NM to the freshwater organisms compared to nano-TiO₂ and nano-SiO₂. Nano-ZnO was the most toxic NM to R. subcapitata and D. magna, while nano-CuO was found to be very toxic to L. minor. Nano-CuO was very toxic to Caco-2 and HepG2 cells, particularly at the highest tested concentrations, while the other NM showed no toxicity to the different cell lines. The HC₅ and PNEC values are still highly protective, due to data limitations. However, the present study provides consistent evidence of the potential risks of both nano-CuO and nano-ZnO against aquatic organisms and also their effects on public health.

Hepatotoxicity induced by nanomaterials: mechanisms and in vitro models

The unique physicochemical properties of materials at nanoscale have opened a plethora of opportunities for applications in the pharmaceutical and medical field, but also in consumer products from food and cosmetics industries. As a consequence, daily human exposure to nanomaterials through distinct routes is considerable and, therefore, may raise health concerns. Many nanomaterials have been described to accumulate and induce adversity in the liver. Among these, silica and some types of metallic nanoparticles are the most broadly used in consumer products and, therefore, the most studied and reported. The reviewed literature was collected from PubMed.gov during the month of March 2020 using the search words "nanomaterials induced hepatotoxicity", which yielded 181 papers. This present paper reviews the hepatotoxic effects of nanomaterials described in in vitro and in vivo studies, with emphasis on the underlying mechanisms. The induction of oxidative stress and inflammation are the manifestations of toxicity most frequently reported following exposure of cells or animal models to different nanomaterials. Furthermore, the available in vitro models for the evaluation of the hepatotoxic effects of nanomaterials are discussed, highlighting the continuous interest in the development of more advanced and reliable in vitro models for nanotoxicology.

Gadolinium Oxide Nanoparticles Induce Toxicity in Human Endothelial HUVECs via Lipid Peroxidation, Mitochondrial Dysfunction and Autophagy Modulation

In spite of the potential preclinical advantage of Gd₂O₃ nanoparticles (designated here as GO NPs) over gadolinium-based compounds in MRI, recent concerns of gadolinium deposits in various tissues undergoing MRI demands a mechanistic investigation. Hence, we chose human to measure umbilical vein endothelial cells (HUVECs) that line the vasculature and relevant biomarkers due to GO NPs exposure in parallel with the NPs of ZnO as a positive control of toxicity. GO NPs, as measured by TEM, had an average length of 54.8 ± 29 nm and a diameter of 13.7 ± 6 nm suggesting a fiber-like appearance. With not as pronounced toxicity associated with a 24-h exposure, GO NPs induced a concentration-dependent cytotoxicity (IC₅₀ = 304 ± 17 µg/mL) in HUVECs when exposed for 48 h. GO NPs emerged as significant inducer of lipid peroxidation (LPO), reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and autophagic vesicles in comparison to that caused by ZnO NPs at its IC₅₀ for the same exposure time (48 h). While ZnO NPs clearly appeared to induce apoptosis, GO NPs revealed both apoptotic as well as necrotic potentials in HUVECs. Intriguingly, the exogenous antioxidant NAC (N-acetylcysteine) co-treatment significantly attenuated the oxidative imbalance due to NPs preventing cytotoxicity significantly.

Ultrafine silicon dioxide nanoparticles cause lung epithelial cells apoptosis via oxidative stress-activated PI3K/Akt-mediated mitochondria- and endoplasmic reticulum stress-dependent signaling pathways

Silicon dioxide nanoparticles (SiO₂NPs) are widely applied in industry, chemical, and cosmetics. SiO₂NPs is known to induce pulmonary toxicity. In this study, we investigated the molecular mechanisms of SiO₂NPs on pulmonary toxicity using a lung alveolar epithelial cell (L2) model. SiO₂NPs, which primary particle size was 12 nm, caused the accumulation of intracellular Si, the decrease in cell viability, and the decrease in mRNAs expression of surfactant, including surfactant protein (SP)-A, SP-B, SP-C, and SP-D. SiO₂NPs induced the L2 cell apoptosis. The increases in annexin V fluorescence, caspase-3 activity, and protein expression of cleaved-poly (ADP-ribose) polymerase (PARP), cleaved-caspase-9, and cleaved-caspase-7 were observed. The SiO₂NPs induced caspase-3 activity was reversed by pretreatment of caspase-3 inhibitor Z-DEVD-FMK. SiO₂NPs exposure increased reactive oxygen species (ROS) production, decreased mitochondrial transmembrane potential, and decreased protein and mRNA expression of Bcl-2 in L2 cells. SiO₂NPs increased protein expression of cytosolic cytochrome c and Bax, and mRNAs expression of Bid, Bak, and Bax. SiO₂NPs could induce the endoplasmic reticulum (ER) stress-related signals, including the increase in CHOP, XBP-1, and phospho-eIF2α protein expressions, and the decrease in pro-caspase-12 protein expression. SiO₂NPs increased phosphoinositide 3-kinase (PI3K) activity and AKT phosphorylation. Both ROS inhibitor N-acetyl-l-cysteine (NAC) and PI3K inhibitor LY294002 reversed SiO₂NPs-induced signals described above. However, the LY294002 could not inhibit SiO₂NPs-induced ROS generation. These findings demonstrated first time that SiO₂NPs induced L2 cell apoptosis through ROS-regulated PI3K/AKT signaling and its downstream mitochondria- and ER stress-dependent signaling pathways.

Amorphous nanosilica induced toxicity, inflammation and innate immune responses: A critical review

Nanoparticles are promising bioengineering platforms facilitating various consumer product formulations, including packaged food, electrical, biosensor and biomedical tools. The unique surface and physicochemical properties of amorphous nanosilica supports advanced nano-biomolecular applications for various manufacturing, biotechnology, and healthcare industries including cosmetics, packaging, implants, drug delivery systems and cancer diagnostics. The increased technological and economic benefits of amorphous nanosilica, raises concerns regarding their adverse biological effects on humans. The cellular mechanisms underlying amorphous nanosilica internalization, evasion of biological barriers, inadvertent nano-bio interactions and unexpected long term exposure effects must be taken into consideration from the diverse ecosystems and human safety aspects. Recent research studies reveal cytotoxic, inflammatory and immunomodulatory effects of amorphous nanosilica particles. Our review focuses on studies demonstrating hazardous impact of amorphous nanosilica/bio-systems interface on the cellular and biochemical processes. The review further seeks to evaluate amorphous nanosilica-induced cytotoxicity, innate immune responses, inflammation and immune related dysfunctions, and discuss open research questions related to the use of amorphous nanosilica in biomedicine.

Mathematical modeling of cytotoxicity of metal oxide nanoparticles using the index of ideality correlation criteria

Several types of metal oxide nanoparticles (MO-NPs) are often utilized as one of the novel class of materials in the pharmaceutical industry and human health. The wide use of MO-NPs forces an enhanced understanding of their potential impact on human health and the environment. The research aims to investigate and develop a nano-QFAR (nano-quantitative feature activity relationship) model applying the quasi-SMILES such as cell line, assay, time exposition, concentration, nanoparticles size and metal oxide type for prediction of cell viability (%) of MO-NPs. The total set of 83 quasi-SMILES of MO-NPs divided into training, validation and test sets randomly three times. The statistical model results based on the balance of correlation target function (TF₁) and index of ideality correlation target function (TF₂) and the Monte Carlo optimization were compared. The comparison of two target function results indicated that TF₂ improves the predictability of models. The significance of various eclectic features of both increase and decrease of cell viability (%) is provided. Mechanistic interpretation of significant factors for the model are proposed as well. The sufficient statistical quality of three nano-QFAR models based on TF₂ reveals that the developed models can be efficiency for predictions of the cell viability (%) of MO-NPs.

Silica dioxide nanoparticles aggravate airway inflammation in an asthmatic mouse model via NLRP3 inflammasome activation

Silica dioxide nanoparticles (SiONPs) are mainly used in the rubber industry; however, they are a major air pollutant in Asia. Thus, extensive research on this issue is required. In this study, we investigated the effects of SiONPs on asthma aggravation and elucidated the underlying mechanism using ovalbumin (OVA)-induced asthmatic mice model and in NCI-H292 cells. Mice exposed to SiONPs showed markedly increased Penh values, inflammatory cell counts, and inflammatory cytokine levels compared to OVA-induced asthmatic mice. Exposure to SiONPs also induced additional airway inflammation and mucus secretion with increases in protein expression levels of thioredoxin-interacting protein (TXNIP), NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, and interleukin (IL)-1β compared to those in OVA-induced asthmatic mice. Treatment of SiONPs in NCI-H292 cells also significantly increased mRNA expression levels of inflammatory cytokines accompanied with elevation in the levels of TXNIP, NLRP3 inflammasome, and IL-1β proteins in a concentration-dependent manner. Taken together, exposure to SiONPs aggravated asthma development, which is closely related to inflammasome activation. Our results provide useful information about the toxicological effects of SiONPs on asthma exacerbation and suggest the need to avoid SiONP exposure especially in individuals with respiratory diseases.

Influence of nanoparticles on liver tissue and hepatic functions: A review

Due to the increasing interest in nanotechnology in very large application fields, including biotechnology, electronics and food industries, humans are increasingly exposed to nanoparticles (NPs). Consequently, the question about the safety of these nanomaterials and their impact on human health is a legitimate concern. The liver is the primary organ of detoxification and is one of the tissues that is most exposed to NPs. When they reach the bloodstream, NPs are mainly internalized by liver cells. This review focuses on recent in vitro and in vivo studies addressing the effects of organic and inorganic NPs on the liver. Specifically, the impact of the NPs on hepatic enzyme activities, the inflammatory response and genotoxicity processes will be described. Depending on the physicochemical parameters of the NPs and the conditions of exposure, NPs could lead to global liver injury.

Endoplasmic Reticulum Stress Cooperates in Silica Nanoparticles-Induced Macrophage Apoptosis via Activation of CHOP-Mediated Apoptotic Signaling Pathway

While silica nanoparticles (SiNPs) have wide applications, they inevitably increase atmospheric particulate matter and human exposure to this nanomaterial. Numerous studies have focused on how to disclose SiNP toxicity and on understanding its toxic mechanisms. However, there are few studies in the literature reporting the interaction between endoplasmic reticulum (ER) stress and SiNP exposure, and the corresponding detailed mechanisms have not been clearly determined. In this study, CCK-8 and flow cytometry assays demonstrated that SiNPs gradually decreased cell viability and increased cell apoptosis in RAW 264.7 macrophage cells in dose- and time-dependent manners. Western blot analysis showed that SiNPs significantly activated ER stress by upregulating GRP78, CHOP, and ERO1α expression. Meanwhile, western blot analysis also showed that SiNPs activated the mitochondrial-mediated apoptotic signaling pathway by upregulating BAD and Caspase-3, and downregulating the BCL-2/BAX ratio. Moreover, 4-phenylbutyrate (4-PBA), an ER stress inhibitor, significantly decreased GRP78, CHOP, and ERO1α expression, and inhibited cell apoptosis in RAW 264.7 macrophage cells. Furthermore, overexpression of CHOP significantly enhanced cell apoptosis, while knockdown of CHOP significantly protected RAW 264.7 macrophage cells from apoptosis induced by SiNPs. We found that the CHOP-ERO1α-caspase-dependent apoptotic signaling pathway was activated by upregulating the downstream target protein ERO1α and caspase-dependent mitochondrial-mediated apoptotic signaling pathway by upregulating Caspase-3 and downregulating the ratio of BCL-2/BAX. In summary, ER stress participated in cell apoptosis induced by SiNPs and CHOP regulated SiNP-induced cell apoptosis, at least partly, via activation of the CHOP-ERO1α-caspase apoptotic signaling pathway in RAW 264.7 macrophage cells.

Genetic Circuits To Detect Nanomaterial Triggered Toxicity through Engineered Heat Shock Response Mechanism

Biocompatibility assessment of nanomaterials has been of great interest due to their potential toxicity. However, conventional biocompatibility tests fall short of providing a fast toxicity report. We developed a whole cell based biosensor to track biocompatibility of nanomaterials with the aim of providing fast feedback to engineer them with lower toxicity levels. We engineered promoters of four heat shock response (HSR) proteins utilizing synthetic biology approaches. As an initial design, a reporter coding gene was cloned downstream of the selected promoter regions. Initial results indicated that native heat shock protein (HSP) promoter regions were not very promising to generate signals with low background signals. Introducing riboregulators to native promoters eliminated unwanted background signals almost entirely. Yet, this approach also led to a decrease in expected sensor signal upon stress treatment. Thus, a repression based genetic circuit, inspired by the HSR mechanism of Mycobacterium tuberculosis, was constructed. These genetic circuits could report the toxicity of quantum dot nanoparticles in 1 h. Our designed nanoparticle toxicity sensors can provide quick reports, which can lower the demand for additional experiments with more complex organisms.

A reliable approach for assessing size-dependent effects of silica nanoparticles on cellular internalization behavior and cytotoxic mechanisms

Background

The size of nanoparticles is considered to influence their toxicity, as smaller-sized nanoparticles should more easily penetrate the cell and exert toxic effects. However, conflicting results and unstandardized methodology have resulted in controversy of these size-dependent effects. Here, we introduce a unique approach to study such size-dependent effects of nanoparticles and present evidence that reliably supports this general assumption along with elucidation of the underlying cytotoxic mechanism.

Methods

We prepared and physically characterized size-controlled (20-50 nm) monodispersed silica nanoparticles (SNPs) in aqueous suspensions. Then, a variety of biochemical assessments are used for evaluating the cytotoxic mechanisms.

Results

SNP treatment in three cell lines decreased cell viability and migration ability, while ROS production increased in dose- and size-dependent manners, with SNPs <30 nm showing the greatest effects. 30- and 40-nm SNPs were observed similar to these biological activities of 20- and 50-nm, respectively. Under the conventionally used serum-free conditions, both 20-nm and 50-nm SNPs at the IC₅₀ values (75.2 and 175.2 μg/mL) induced apoptosis and necrosis in HepG2 cells, whereas necrosis was more rapid with the smaller SNPs. Inhibiting endocytosis impeded the internalization of the 50-nm but not the 20-nm SNPs. However, agglomeration following serum exposure increased the size of the 20-nm SNPs to approximately 50 nm, preventing their internalization and cell membrane damage without necrosis. Thus, 20-nm and 50-nm SNPs show different modes of cellular uptake, with smaller SNPs capable of trafficking into the cells in an endocytosis-independent manner. This approach of using non-overlapping size classes of SNPs under the same dose, along with serum-induced agglomeration analysis clarifies this long-standing question about the safety of small SNPs.

Conclusion

Our results highlight the need to revise safety guidelines to account for this demonstrated size-dependent cytotoxicity under serum-free conditions, which may be similar to the microenvironment after tissue penetration.

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.

Silica Nanoparticles Provoke Cell Death Independent of p53 and BAX in Human Colon Cancer Cells

Several in vitro studies have suggested that silica nanoparticles (NPs) might induce adverse effects in gut cells. Here, we used the human colon cancer epithelial cell line HCT116 to study the potential cytotoxic effects of ingested silica NPs in the presence or absence of serum. Furthermore, we evaluated different physico-chemical parameters important for the assessment of nanoparticle safety, including primary particle size (12, 70, 200, and 500 nm) and surface modification (-NH2 and -COOH). Silica NPs triggered cytotoxicity, as evidenced by reduced metabolism and enhanced membrane leakage. Automated microscopy revealed that the silica NPs promoted apoptosis and necrosis proportional to the administered specific surface area dose. Cytotoxicity of silica NPs was suppressed by increasing amount of serum and surface modification. Furthermore, inhibition of caspases partially prevented silica NP-induced cytotoxicity. In order to investigate the role of specific cell death pathways in more detail, we used isogenic derivatives of HCT116 cells which lack the pro-apoptotic proteins p53 or BAX. In contrast to the anticancer drug cisplatin, silica NPs induced cell death independent of the p53-BAX axis. In conclusion, silica NPs initiated cell death in colon cancer cells dependent on the specific surface area and presence of serum. Further studies in vivo are warranted to address potential cytotoxic actions in the gut epithelium. The unintended toxicity of silica NPs as observed here could also be beneficial. As loss of p53 in colon cancer cells contributes to resistance against anticancer drugs, and thus to reoccurrence of colon cancer, targeted delivery of silica NPs could be envisioned to also deplete p53 deficient tumor cells.

The Influence of Polysaccharide Coating on the Physicochemical Parameters and Cytotoxicity of Silica Nanoparticles for Hydrophilic Biomolecules Delivery

The present work reports the effect of polysaccharides (chitosan and sodium alginate) on silica nanoparticles (SiNP) for hydrophilic molecules delivery taking insulin as model drug. The influence of tetraethyl orthosilicate (TEOS) and homogenization speed on SiNP properties was assessed by a 22 factorial design achieving as optimal parameters: 0.43 mol/L of TEOS and homogenization speed of 5000 rpm. SiNP mean particle size (Z-Ave) was of 256.6 nm and polydispersity index (PI) of 0.218. SiNP coated with chitosan (SiNP-CH) or sodium alginate (SiNP-SA) increased insulin association efficacy; reaching 84.6% (SiNP-SA) and 90.8% (SiNP-CH). However, coated SiNP released 50%-60% of the peptide during the first 45 min at acidic environment, while uncoated SiNP only released 30%. Similar results were obtained at pH 6.8. The low Akaike's (AIC) values indicated that drug release followed Peppas model for SiNP-SA and second order for uncoated SiNP and SiNP-CH (pH 2.0). At pH 6.8, the best fitting was Boltzmann for Ins-SiNP. However, SiNP-CH and SiNP-SA showed a first-order behavior. Cytotoxicity of nanoparticles, assessed in Caco-2 and HepG2 cells, showed that 100 to 500 µg/mL SiNP-CH and SiNP-SA slightly decreased cell viability, comparing with SiNP. In conclusion, coating SiNP with selected polysaccharides influenced the nanoparticles physicochemical properties, the insulin release, and the effect of these nanoparticles on cell viability.

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.

Delivery of Conjugated Silicon Dioxide Nanoparticles Show Strong Anti-Proliferative Activities

Conjugation of different molecules is a promising approach to enhance the drug delivery and treatment. In the present study, here, we have synthesized silica oxide (SiO₂) nanoparticles conjugated with (3-Glycidyloxypropyl) trimethoxysilane (3GPS) and further reacted with 1,2,4-triazole (Tri), 3-aminotriazole (ATri), 5-aminetetrazole (Atet), imidazole (Imi). The structure, size, and morphology of nanocomposite materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) methods. These nanocomposite materials were tested on human colorectal carcinoma cells (HCT-116) to examine their anti-cancer capabilities by using MTT assay and morphometric analysis. Our results revealed that nanocomposite materials decreased cancer cell viability and cell proliferation and caused cell death in a concentration-dependent manner. Our findings demonstrate that SiO₂-conjugated nanocomposite materials possess strong anti-cancer capabilities and hold a great potential for the colon cancer treatments.

Tailoring Cell Morphomechanical Perturbations Through Metal Oxide Nanoparticles

The nowadays growing use of nanoparticles (NPs) in commercial products does not match a comprehensive understanding of their potential harmfulness. More in vitro investigations are required to address how the physicochemical properties of NPs guide their engulfment within cells and their intracellular trafficking, fate, and toxicity. These nano-bio interactions have not been extensively addressed yet, especially from a mechanical viewpoint. Cell mechanic is a critical indicator of cell health because it regulates processes like cell migration, tissue integrity, and differentiation via cytoskeleton rearrangements. Here, we investigated in vitro the elasticity perturbation of Caco-2 and A549 cell lines, in terms of Young's modulus modification induced by SiO2NPS and TiO2NPS. TiO2NPs demonstrated stronger effects on cell elasticity compared to SiO2NPs, as they induced significant morphological and morphometric changes in actin network. TiO2NPS increased the elasticity in Caco-2 cells, while opposite effects have been observed on A549 cells. These results demonstrate the existence of a correlation between the alteration of cell elasticity and NPs toxicity that depends, in turn, on the NPs physicochemical properties and the specific cell tested.

Sub-acute oral exposure of zinc oxide nanoparticles causes alteration in iron homeostasis through acute phase response: A protective effect by surface modification

Zinc oxide nanoparticles (ZnO NPs) are one of the most widely used nanomaterials. Following oral exposure, these NPs can accumulate in various organs and induce the toxicity due to their physiochemical characteristics. In present study to reduce the toxicity, surface engineered ZnO NPs (c-ZnO NPs) were in-situ synthesized by using polyacrylamide grafted guar gum (PAm-g-GG) polymer in alkaline media. Further, the comparative effect of bared ZnO NPs (b-ZnO NPs) and c-ZnO NPs were assessed on secondary target organ liver and kidneys of Swiss mice at doses of 10, 50 and 300 mg/kg following 28 days repeated oral treatment. The b-ZnO NPs were incited severe damages in liver and kidney tissue than c-ZnO NPs as seen by transmission electron microscopy and histopathology. The increased levels of serum biomarkers (AST, ALT, ALP, creatinine, uric acid, and urea) were also observed, that remarking a disturbance in the function of liver and kidney. After sub-acute oral treatment of b-ZnO NPs, the hepatic pro-inflammatory cytokines (IL-6, TNF-α, and MMP-9) were up-regulated that causes the activation of acute phase response (APR). We also observed significantly increased in expression of hepatic acute phase proteins (hepcidin and haptoglobin) and altered interlinked iron (Fe) signaling biomarkers (hephaestin, TF, TFR-1, LDH, and ferroportin). This study emphasizes that exposure to ZnO NPs may cause inflammation mediated APR through ultra-structural damage of tissue that could escort the progression of anemia. Nevertheless, the capping with PAm-g-GG in c- ZnO NPs has reduced the toxicity by altering the surface reactive property of ZnO NPs.

Two distinct cellular pathways leading to endothelial cell cytotoxicity by silica nanoparticle size

Background

Silica nanoparticles (SiNPs) are widely used for biosensing and diagnostics, and for the targeted delivery of therapeutic agents. Safety concerns about the biomedical and clinical applications of SiNPs have been raised, necessitating analysis of the effects of their intrinsic properties, such as sizes, shapes, and surface physicochemical characteristics, on human health to minimize risk in biomedical applications. In particular, SiNP size-associated toxicological effects, and the underlying molecular mechanisms in the vascular endothelium remain unclear. This study aimed to elucidate the detailed mechanisms underlying the cellular response to exposure to trace amounts of SiNPs and to determine applicable size criteria for biomedical application.

Methods

To clarify whether these SiNP-mediated cytotoxicity due to induction of apoptosis or necrosis, human ECs were treated with SiNPs of four different non-overlapping sizes under low serum-containing condition, stained with annexin V and propidium iodide (PI), and subjected to flow cytometric analysis (FACS). Two types of cell death mechanisms were assessed in terms of production of reactive oxygen species (ROS), endoplasmic reticulum (ER) stress induction, and autophagy activity.

Results

Spherical SiNPs had a diameter of 21.8 nm; this was further increased to 31.4, 42.9, and 56.7 nm. Hence, we investigated these effects in human endothelial cells (ECs) treated with these nanoparticles under overlap- or agglomerate-free conditions. The 20-nm SiNPs, but not SiNPs of other sizes, significantly induced apoptosis and necrosis. Surprisingly, the two types of cell death occurred independently and through different mechanisms. Apoptotic cell death resulted from ROS-mediated ER stress. Furthermore, autophagy-mediated necrotic cell death was induced through the PI3K/AKT/eNOS signaling axis. Together, the present results indicate that SiNPs within a diameter of < 20-nm pose greater risks to cells in terms of cytotoxic effects.

Conclusion

These data provide novel insights into the size-dependence of the cytotoxic effects of silica nanoparticles and the underlying molecular mechanisms. The findings are expected to inform the applicable size range of SiNPs to ensure their safety in biomedical and clinical applications.

Electronic supplementary material

The online version of this article (10.1186/s12951-019-0456-4) contains supplementary material, which is available to authorized users.

Impact of Surface-Engineered ZnO Nanoparticles on Protein Corona Configuration and Their Interactions With Biological System

In biological system, the interaction between nanoparticles (NPs) and serum biomolecules results in the formation of a dynamic corona of different affinities. The formed corona enriched with opsonin protein is recognized by macrophages and immune effector cells, resulting in rapid clearance with induced toxicity. Hence, to reduce corona genesis, surface-engineered ZnO (c-ZnO) NPs were in situ synthesized using a polyacrylamide-grafted guar gum (PAm-g-GG) polymer that provided surface neutrality to the NPs. Furthermore, we studied the characteristics of the corona formed onto uncapped anionic ZnO (bared ZnO [b-ZnO]) NPs and c-ZnO NPs by serum incubation. The result shows that b-ZnO NPs were wrapped with a high amount of serum proteins, particularly opsonin (IgG and complement), compared with c-ZnO NPs. These corona findings helped us substantially in interpretation of in vivo biokinetics studies. The in vivo study was accomplished by oral administration of NPs to Swiss mice at doses of 300 and 2000 mg/kg body weight. The studies performed on the cellular uptake, intracellular particle distribution, cytotoxicity, and pharmacokinetics of NPs indicated that b-ZnO NPs experienced higher immune cell recognition, hepatic inflammation, and resultant rapid clearance from the system, unlike c-ZnO NPs. Thus, capping of NPs by a neutral polymer has provided limited binding sites for undesired proteins around NPs, which limits immune system activation.