The role of reactive oxygen species in the genotoxicity of surface-modified magnetite nanoparticles

Structural investigation of Ayurveda Lauha (Iron) Bhasma

In Ayurveda, 'Lauha' (Iron) Bhasma is primarily used to cure diseases related to iron deficiency in humans. It is produced from purified raw metallic iron using a combination of multi-step traditional preparation processes described in the Ayurveda literature. Here, we present the results of structural investigation performed on the medicinal grade 'Lauha' Bhasma using various X-ray based techniques. Our results indicate that after several rounds of heating and cooling in specific conditions following the Ayurvedic preparation procedure, metallic iron eventually converts to a natural iron-oxide mineral belonging to the magnetite group. Scanning electron microscopy (SEM) and X-ray standing wave assisted fluorescence measurements carried out on powdered Bhasma specimen reveal that the magnetite micro-particles in the Bhasma specimen are usually present in the form of agglomerates of nano-particles. We anticipate that the Ayurvedic Lauha Bhasma has great potential for noninvasive localized target killing of cancer cells, particularly in sensitive parts of the human body such as the brain, spinal cord, and lungs, via necrosis by application of an alternating external magnetic field or photo electron generation through X-rays.

Influence of PEG Chain Length of Functionalized Magnetic Nanoparticles on the Cytocompatibility and Immune Competence of Primary Murine Macrophages and Dendritic Cells

A major drawback of nanoparticles (NPs) for biomedical applications is their preferential phagocytosis in immune cells, which can be avoided by surface modifications like PEGylation. Nevertheless, examinations of different polyethylene glycol (PEG) chain lengths on the competence of immune cells as well as possible immunotoxic effects are still sparse. Therefore, primary murine macrophages and dendritic cells were generated and incubated with magnetic nanoporous silica nanoparticles (MNPSNPs) modified with different mPEG chains (2 kDa, 5 kDa, and 10 kDa). Cytotoxicity, cytokine release, and the formation of reactive oxygen species (ROS) were determined. Immune competence of both cell types was examined and uptake of MNPSNPs into macrophages was visualized. Concentrations up to 150 µg/mL MNPSNPs showed no effects on the metabolic activity or immune competence of both cell types. However, ROS significantly increased in macrophages incubated with larger PEG chains, while the concentration of cytokines (TNF-α and IL-6) did not indicate a proinflammatory process. Investigations on the uptake of MNPSNPs revealed no differences in the onset of internalization and the intensity of intracellular fluorescence. The study gives no indication for an immunotoxic effect of PEGylated MNPSNPs. Nevertheless, there is still a need for optimization regarding their internalization to ensure an efficient drug delivery.

Study of Cytotoxicity and Internalization of Redox-Responsive Iron Oxide Nanoparticles on PC-3 and 4T1 Cancer Cell Lines

Redox-responsive and magnetic nanomaterials are widely used in tumor treatment separately, and while the application of their combined functionalities is perspective, exactly how such synergistic effects can be implemented is still unclear. This report investigates the internalization dynamics of magnetic redox-responsive nanoparticles (MNP-SS) and their cytotoxicity toward PC-3 and 4T1 cell lines. It is shown that MNP-SS synthesized by covalent grafting of polyethylene glycol (PEG) on the magnetic nanoparticle (MNP) surface via SS-bonds lose their colloidal stability and aggregate fully in a solution containing DTT, and partially in conditioned media, whereas the PEGylated MNP (MNP-PEG) without S-S linker control remains stable under the same conditions. Internalized MNP-SS lose the PEG shell more quickly, causing enhanced magnetic core dissolution and thus increased toxicity. This was confirmed by fluorescence microscopy using MNP-SS dual-labeled by Cy3 via labile disulfide, and Cy5 via a rigid linker. The dyes demonstrated a significant difference in fluorescence dynamics and intensity. Additionally, MNP-SS demonstrate quicker cellular uptake compared to MNP-PEG, as confirmed by TEM analysis. The combination of disulfide bonds, leading to faster dissolution of the iron oxide core, and the high-oxidative potential Fe³⁺ ions can synergically enhance oxidative stress in comparison with more stable coating without SS-bonds in the case of MNP-PEG. It decreases the cancer cell viability, especially for the 4T1, which is known for being sensitive to ferroptosis-triggering factors. In this work, we have shown the effect of redox-responsive grafting of the MNP surface as a key factor affecting MNP-internalization rate and dissolution with the release of iron ions inside cancer cells. This kind of synergistic effect is described for the first time and can be used not only in combination with drug delivery, but also in treatment of tumors responsive to ferroptosis.

Evaluation of In Vitro Cytotoxic, Genotoxic, Apoptotic, and Cell Cycle Arrest Potential of Iron-Nickel Alloy Nanoparticles

The use of iron-nickel alloy nanoparticles (Fe-Ni ANPs) is increasing daily in various fields. People are increasingly exposed to these nanoparticles for occupational and environmental reasons. Our study determined some of the effects of Fe-Ni ANP exposure and impacts on human health at the cellular level. The cytotoxic and genotoxic potentials of Fe-Ni ANPs were investigated by XTT, clonogenic, comet, and GammaH2AX analyses using Beas-2B cells. Annexin V, multicaspase, and cell cycle arrest methods were used to understand the apoptotic mechanism of action. The intracellular ROS method was used to determine the primary mechanism that leads to cytotoxic and genotoxic activity. The Fe-Ni ANPs showed cytotoxic activity with the XTT and clonogenic methods: they had genotoxic potential, as demonstrated via genotoxicity methods. It was determined that the cytotoxic effect was realized by the caspase-dependent apoptotic pathway, and the cells were stopped at the G0/G1 stage by Fe-Ni ANPs. Increased intracellular ROS due to Fe-Ni ANPs led to cytotoxic, genotoxic, and apoptotic activity. Potential risks to human health due to Fe-Ni ANPs were then demonstrated at the cellular level.

Superparamagnetic iron oxide nanoparticles for magnetic hyperthermia: Recent advancements, molecular effects, and future directions in the omics era

Superparamagnetic iron oxide nanoparticles have attracted attention in the biomedical field thanks to their ability to prompt hyperthermia in response to an alternated magnetic field. Hyperthermia is well-known for inducing...

Genotoxic Potential of Nanoparticles: Structural and Functional Modifications in DNA

The rapid advancement of nanotechnology enhances the production of different nanoparticles that meet the demand of various fields like biomedical sciences, industrial, material sciences and biotechnology, etc. This technological development increases the chances of nanoparticles exposure to human beings, which can threaten their health. It is well known that various cellular processes (transcription, translation, and replication during cell proliferation, cell cycle, cell differentiation) in which genetic materials (DNA and RNA) are involved play a vital role to maintain any structural and functional modification into it. When nanoparticles come into the vicinity of the cellular system, chances of uptake become high due to their small size. This cellular uptake of nanoparticles enhances its interaction with DNA, leading to structural and functional modification (DNA damage/repair, DNA methylation) into the DNA. These modifications exhibit adverse effects on the cellular system, consequently showing its inadvertent effect on human health. Therefore, in the present study, an attempt has been made to elucidate the genotoxic mechanism of nanoparticles in the context of structural and functional modifications of DNA.

Differences in surface chemistry of iron oxide nanoparticles result in different routes of internalization

The efficient entry of nanotechnology-based pharmaceuticals into target cells is highly desired to reach high therapeutic efficiency while minimizing the side effects. Despite intensive research, the impact of the surface coating on the mechanism of nanoparticle uptake is not sufficiently understood yet. Herein, we present a mechanistic study of cellular internalization pathways of two magnetic iron oxide nanoparticles (MNPs) differing in surface chemistry into A549 cells. The MNP uptake was investigated in the presence of different inhibitors of endocytosis and monitored by spectroscopic and imaging techniques. The results revealed that the route of MNP entry into cells strongly depends on the surface chemistry of the MNPs. While serum bovine albumin-coated MNPs entered the cells via clathrin-mediated endocytosis (CME), caveolin-mediated endocytosis (CavME) or lipid rafts were preferentially involved in the internalization of polyethylene glycol-coated MNPs. Our data indicate that surface engineering can contribute to an enhanced delivery efficiency of nanoparticles.

Antifungal and antiovarian cancer properties of α Fe2O3 and α Fe2O3/ZnO nanostructures synthesised by Spirulina platensis

Candida albicans (C. albicans) infection shows a growing burden on human health, and it has become challenging to search for treatment. Therefore, this work focused on the antifungal activity, and cytotoxic effect of biosynthesised nanostructures on human ovarian tetracarcinoma cells PA1 and their corresponding mechanism of cell death. Herein, the authors fabricated advanced biosynthesis of uncoated α-Fe2O3 and coated α-Fe2O3 nanostructures by using the carbohydrate of Spirulina platensis. The physicochemical features of nanostructures were characterised by UV-visible, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The antifungal activity of these nanostructures against C. albicans was studied by the broth dilution method, and examined by 2', 7'-dichlorofluorescein diacetate staining. However, their cytotoxic effects against PA1 cell lines were evaluated by MTT and comet assays. Results indicated characteristic rod-shaped nanostructures, and increasing the average size of α-Fe2O3@ZnO nanocomposite (105.2 nm × 29.1 nm) to five times as compared to α-Fe2O3 nanoparticles (20.73nm × 5.25 nm). The surface coating of α-Fe2O3 by ZnO has increased its antifungal efficiency against C. albicans. Moreover, the MTT results revealed that α-Fe2O3@ZnO nanocomposite reduces PA1 cell proliferation due to DNA fragmentation (IC50 18.5 μg/ml). Continual advances of green nanotechnology and promising findings of this study are in favour of using the construction of rod-shaped nanostructures for therapeutic applications.

Organ-specific toxicity of magnetic iron oxide-based nanoparticles

The unique properties of magnetic iron oxide nanoparticles determined their widespread use in medical applications, the food industry, textile industry, which in turn led to environmental pollution. These factors determine the long-term nature of the effect of iron oxide nanoparticles on the body. However, studies in the field of chronic nanotoxicology of magnetic iron particles are insufficient and scattered. Studies show that toxicity may be increased depending on oral and inhalation routes of administration rather than injection. The sensory nerve pathway can produce a number of specific effects not seen with other routes of administration. Organ systems showing potential toxic effects when injected with iron oxide nanoparticles include the nervous system, heart and lungs, the thyroid gland, and organs of the mononuclear phagocytic system (MPS). A special place is occupied by the reproductive system and the effect of nanoparticles on the health of the first and second generations of individuals exposed to the toxic effects of iron oxide nanoparticles. This knowledge should be taken into account for subsequent studies of the toxicity of iron oxide nanoparticles. Particular attention should be paid to tests conducted on animals with pathologies representing human chronic socially significant diseases. This part of preclinical studies is almost in its infancy but of great importance for further medical translation on nanomaterials to practice.

Nanospheres as a technological alternative to suppress hepatic cellular damage and impaired bioenergetics caused by nerolidol in Nile tilapia (Oreochromis niloticus)

Nerolidol is a sesquiterpene found in essential oils of several plant species. It is found commonly in human and animal diets and is approved by the US Food and Drug Administration as a flavoring agent. Nevertheless, recent studies have suggested that nerolidol has potent hepatotoxic effects. Because use of plant-based products in human and animal food has expanded considerably, it is essential to develop approaches such as nanotechnology to avoid or reduce hepatic toxic effects. Therefore, the aim of the study was to determine whether nerolidol dietary supplementation elicited hepatic damage associated with impairment of energy homeostasis, as well as whether supplementation with nerolidol-loaded in nanospheres prevented hepatotoxic effects in Nile tilapia (Oreochromis niloticus). Nile tilapia were divided into five groups (A-E, n = 10 per group) with four replicates each, as follows: group A received basal feed (without supplementation); group B received feed containing 0.5 mL free nerolidol/kg; group C received feed containing 1.0 mL free nerolidol/kg; group D received feed containing 0.5 mL nanospheres nerolidol/kg; and group E received feed containing 1.0 mL nanospheres nerolidol/kg. All groups received experimental feed once a day (10% total biomass) at 2 p.m. for 60 consecutive days. Hepatic liver weight and relative liver weight were significantly lower in fish fed 1.0 mL free nerolidol/kg feed than in fish given basal diet (control group). Hepatic pyruvate kinase (1.0 mL free nerolidol/kg) and adenylate kinase (0.5 and 1.0 mL free nerolidol/kg) activities were significantly lower than in the control group, while hepatic reactive oxygen species and lipid damage levels were significantly higher. Finally, the comet assay revealed significant increases in the frequency of damage and the damage index in fish given 0.5 and 1.0 mL free nerolidol/kg in a dose-dependent manner. Nerolidol-loaded in nanospheres prevented all alterations elicited by free nerolidol. Based on these data, we concluded that dietary supplementation with free nerolidol elicited severe impairment of hepatic bioenergetics homeostasis that appeared to be mediated by excessive ROS production and lipid damage, contributing to a genotoxic effect. Dietary supplementation with nerolidol-loaded in nanospheres did not elicit hepatic damage, and therefore, should be considered as a replacement so as to limit toxicity, permitting its continued use as a dietary supplement.

Surface coating determines the inflammatory potential of magnetite nanoparticles in murine renal podocytes and mesangial cells

Primary renal podocytes are more susceptible to MNPs exposure than primary renal mesangial cells.

Iron Oxide Nanoparticle-Induced Neoplastic-Like Cell Transformation in Vitro Is Reduced with a Protective Amorphous Silica Coating

Iron oxide nanoparticles (IONP) have recently surged in production and use in a wide variety of biomedical and environmental applications. However, their potential long-term health effects, including carcinogenesis, are unknown. Limited research suggests IONP can induce genotoxicity and neoplastic transformation associated with particle dissolution and release of free iron ions. "Safe by design" strategies involve the modification of particle physicochemical properties to affect subsequent adverse outcomes, such as an amorphous silica coating to reduce IONP dissolution and direct interaction with cells. We hypothesized that long-term exposure to a specific IONP (nFe₂O₃) would induce neoplastic-like cell transformation, which could be prevented with an amorphous silica coating (SiO₂-nFe₂O₃). To test this hypothesis, human bronchial epithelial cells (Beas-2B) were continuously exposed to a 0.6 μg/cm² administered a dose of nFe₂O₃ (∼0.58 μg/cm² delivered dose), SiO₂-nFe₂O₃ (∼0.55 μg/cm² delivered dose), or gas metal arc mild steel welding fumes (GMA-MS, ∼0.58 μg/cm² delivered dose) for 6.5 months. GMA-MS are composed of roughly 80% iron/iron oxide and were recently classified as a total human carcinogen. Our results showed that low-dose/long-term in vitro exposure to nFe₂O₃ induced a time-dependent neoplastic-like cell transformation, as indicated by increased cell proliferation and attachment-independent colony formation, which closely matched that induced by GMA-MS. This transformation was associated with decreases in intracellular iron, minimal changes in reactive oxygen species (ROS) production, and the induction of double-stranded DNA damage. An amorphous silica-coated but otherwise identical particle (SiO₂-nFe₂O₃) did not induce this neoplastic-like phenotype or changes in the parameters mentioned above. Overall, the presented data suggest the carcinogenic potential of long-term nFe₂O₃ exposure and the utility of an amorphous silica coating in a "safe by design" hazard reduction strategy, within the context of a physiologically relevant exposure scenario (low-dose/long-term), with model validation using GMA-MS.

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.

IR-enhanced photothermal therapeutic effect of graphene magnetite nanocomposite on human liver cancer HepG2 cell model

Background: Graphene magnetite nanocomposites (G/Fe3O4) exhibit light photothermal conversion upon enhancement by 808 nm IR laser excitation. We evaluated the cytotoxic and photothermal effects of G/Fe3O4 on a HepG2 human liver cancer cell model. Methods: Graphene nanosheets (rGO), magnetite nanoparticles (Fe3O4), and G/Fe3O4 were prepared by chemical methods and characterized using transmission electron microscopy, Raman spectroscopy, zeta analysis, and vibrating sample magnemeter. Dark and light cytotoxicity were screened with colorimetric Sulforhodamine B cell viability assay after 24 and 48 hours. DNA fragmentation and some apoptotic genes on a transcriptional RNA level expression were performed. All prepared nanomaterials were evaluated for their photothermal effect at concentrations of 10 and 50 µg/mL. The power density incident on the cells by 300 mW 808 IR diode laser was 0.597 W/cm2. Results: Treatment of HepG2 with 400 µg/mL of rGO, Fe3O4, and G/Fe3O4 showed alteration in cell morphology after 24 hours of cell treatment and revealed toxic effects on cellular DNA. Evaluation of the cytotoxic effects showed messenger RNA (mRNA) in β-actin and Bax apoptotic genes, but no expression of mRNA of caspase-3 after 24 hours of cell exposure, suggesting the involvement of an intrinsic apoptotic caspase-independent pathway. A photothermal effect was observed for G/Fe3O4 after irradiation of the HepG2 cells. A marked decrease was found in cell viability when treated with 10 and 50 µg/mL G/Fe3O4 from 40% to 5% after 48 hours of cell treatment. Conclusion: Results indicate that G/Fe3O4 nanocomposite was effective at transformation of light into heat and is a promising candidate for cancer therapy.

Silica coated iron oxide nanoparticles-induced cytotoxicity, genotoxicity and its underlying mechanism in human HK-2 renal proximal tubule epithelial cells

Iron oxide nanoparticles (IONPs) have a great potential with regard to cell labelling, cell tracking, cell separation, magnetic resonance imaging, magnetic hyperthermia, targeted drug and gene delivery. However, a growing body of research has raised concerns about the possible unwanted adverse cytotoxic effects of IONPs. In the present study, the in vitro cellular uptake, antiproliferative activity, cytotoxicity, genotoxicity, prooxidant, microtubule-disrupting and apoptosis-inducing effect of Fe₃O₄@SiO₂ and passivated Fe₃O₄@SiO₂-NH₂ nanoparticles on human renal proximal tubule epithelial cells (HK-2) have been studied. Both investigated silica coated IONPs were found to have cell growth-inhibitory activity in a time- and dose-dependent manner. Determination of cell cycle phase distribution by flow cytometry demonstrated a G1 and G2/M phase accumulation of HK-2 cells. A tetrazolium salt cytotoxicity assay at 24 h following treatment demonstrated that cell viability was reduced in a dose-dependent manner. Microscopy observations showed that both Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂-NH₂ nanoparticles accumulated in cells and appeared to have microtubule-disrupting activity. Our study also revealed that short term 1 h exposure to 25 and 100 μg/mL of silica coated IONPs causes genotoxicity. Compared with vehicle control cells, a significantly higher amount of γH2AX foci correlating with an increase in DNA double-strand breaks was observed in Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂-NH₂-treated and immunestained HK-2 cells. The investigated nanoparticles did not trigger significant ROS generation and apoptosis-mediated cell death. In conclusion, these findings provide new insights into the cytotoxicity of silica coated IONPs that may support their further safer use.

Macrophage functionality and homeostasis in response to oligoethyleneglycol-coated IONPs: Impact of a dendritic architecture

The engineering of iron oxide nanoparticles (IONPs) for biomedical use has received great interest over the past decade. In the present study we investigated the biocompatibility of IONPs grafted with linear (2P) or generation 1 (2PG1) or 2 (2PG2) dendronized oligoethyleneglycol units in THP-1-derived macrophages. To evaluate IONP effects on cell functionality and homeostasis, mitochondrial function (MTT assay), membrane permeability (LDH release), inflammation (IL-8), oxidative stress (reduced glutathione, GSH), NLRP3 inflammasome activation (IL-1β) and nanoparticle cellular uptake (intracellular iron content) were quantified after a 4-h or 24-h cell exposure to increasing IONP concentrations (0-300 µg Fe/mL). IONPs coated with a linear molecule, NP10COP@2P, were highly taken up by cells and induced significant dose-dependent IL-8 release, oxidative stress and NLRP3 inflammasome activation. In comparison, IONPs coated with dendrons of generation 1 (NP10COP@2PG1) and 2 (NP10COP@2PG2) exhibited better biocompatibility. Effect of the dendritic architecture of the surface coating was investigated in a kinetic experiment involving cell short-term exposure (30 min or 1 h 30) to the two dendronized IONPs. NP10COP@2PG2 disrupted cellular homeostasis (LDH release, IL-1β and IL-8 secretion) to a greater extend than NP10COP@2PG1, which makes this last IONP the best candidate as MRI contrast or theranostic agent.

Assessment of oxidative damage induced by iron oxide nanoparticles on different nervous system cells

Iron oxide nanoparticles (ION) have received much attention for their utility in biomedical applications, such as magnetic resonance imaging, drug delivery and hyperthermia, but concerns regarding their potential harmful effects are also growing. Even though ION may induce different toxic effects in a wide variety of cell types and animal systems, there is a notable lack of toxicological data on the human nervous system, particularly important given the increasing number of applications on this specific system. An important mechanism of nanotoxicity is reactive oxygen species (ROS) generation and oxidative stress. On this basis, the main objective of this work was to assess the oxidative potential of silica-coated (S-ION) and oleic acid-coated (O-ION) ION on human SH-SY5Y neuronal and A172 glial cells. To this aim, ability of ION to generate ROS (both in the absence and presence of cells) was determined, and consequences of oxidative potential were assessed (i) on DNA by means of the 8-oxo-7,8-dihydroguanine DNA glycosylase (OGG1)-modified comet assay, and (ii) on antioxidant reserves by analyzing ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG). Conditions tested included a range of concentrations, two exposure times (3 and 24 h), and absence and presence of serum in the cell culture media. Results confirmed that, even though ION were not able to produce ROS in acellular environments, ROS formation was increased in the neuronal and glial cells by ION exposure, and was parallel to induction of oxidative DNA damage and, only in the case of neuronal cells treated with S-ION, to decreases in the GSH/GSSG ratio. Present findings suggest the production of oxidative stress as a potential action mechanism leading to the previously reported cellular effects, and indicate that ION may pose a health risk to human nervous system cells by generating oxidative stress, and thus should be used with caution.

Effects of iron oxide contrast agent in combination with various transfection agents during mesenchymal stem cells labelling: An in vitro toxicological evaluation

The use of iron oxide nanoparticles for different biomedical applications, hold immense promise to develop negative tissue contrast in magnetic resonance imaging (MRI). Previously, we have optimized the labelling of mesenchymal stem cells (MSCs) with iron oxide nanoparticles complexed to different transfection agents like poly-l-lysine (IO-PLL) and protamine sulfate (Fe-Pro) on the basis of relaxation behaviour and its biological expressions. However, there is a distinct need to investigate the biocompatibility and biosafety concerns coupled with its cytotoxicity and genotoxicity. This study was prepared to evaluate the viability of cells, generation of ROS, changes in actin cytoskeleton, investigation of cell death, level of GSH and TAC, activities of SOD and GPx, and stability of DNA in MSCs after labelling. Results demonstrated a marginal alteration in toxicological parameters like ROS generation, cell length, actin cytoskeleton, total apoptosis and DNA damage was detected after stem cell labelling. Insignificant depletion of GSH and SOD level, and increase in GPx and TAC level in MSCs were measured after labelling with IO-PLL and Fe-Pro complexes, which later on recovered and normalized to its baseline. This MSCs labelling could provide a reference guideline for toxicological analysis and relaxometry based in vivo MRI detection.

Are iron oxide nanoparticles safe? Current knowledge and future perspectives

Due to their unique physicochemical properties, including superparamagnetism, iron oxide nanoparticles (ION) have a number of interesting applications, especially in the biomedical field, that make them one of the most fascinating nanomaterials. They are used as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Together with these valuable uses, concerns regarding the onset of unexpected adverse health effects following exposure have been also raised. Nevertheless, despite the numerous ION purposes being explored, currently available information on their potential toxicity is still scarce and controversial data have been reported. Although ION have traditionally been considered as biocompatible - mainly on the basis of viability tests results - influence of nanoparticle surface coating, size, or dose, and of other experimental factors such as treatment time or cell type, has been demonstrated to be important for ION in vitro toxicity manifestation. In vivo studies have shown distribution of ION to different tissues and organs, including brain after passing the blood-brain barrier; nevertheless results from acute toxicity, genotoxicity, immunotoxicity, neurotoxicity and reproductive toxicity investigations in different animal models do not provide a clear overview on ION safety yet, and epidemiological studies are almost inexistent. Much work has still to be done to fully understand how these nanomaterials interact with cellular systems and what, if any, potential adverse health consequences can derive from ION exposure.

Skin Corrosion and Irritation Test of Nanoparticles Using Reconstructed Three-Dimensional Human Skin Model, EpiDermTM

Effects of nanoparticles (NPs) on skin corrosion and irritation using three-dimensional human skin models were investigated based on the test guidelines of Organization for Economic Co-operation and Development (OECD TG431 and TG439). EpiDerm^TM skin was incubated with NPs including those harboring iron (FeNPs), aluminum oxide (AlNPs), titanium oxide (TNPs), and silver (AgNPs) for a defined time according to the test guidelines. Cell viabilities of EpiDerm^TM skins were measured by the 3-(4, 5-dimethylthi-azol-2-yl)-2.5-diphenyltetrazolium bromide based method. FeNPs, AlNPs, TNPs, and AgNPs were non-corrosive because the viability was more than 50% after 3 min exposure and more than 15% after 60 min exposure, which are the non-corrosive criteria. All NPs were also non-irritants, based on viability exceeding 50% after 60 min exposure and 42 hr post-incubation. Release of interleukin 1-alpha and histopathological analysis supported the cell viability results. These findings suggest that FeNPs, AlNPs, TNPs, and AgNPs are ‘non-corrosive’ and ‘non-irritant’ to human skin by a globally harmonized classification system.

Surface-modified magnetite nanoparticles act as aneugen-like spindle poison

Iron oxide nanoparticles are one of the most promising types of nanoparticles for biomedical applications, primarily in the context of nanomedicine-based diagnostics and therapy; hence, great attention should be paid to their bio-safety. Here, we investigate the ability of surface-modified magnetite nanoparticles (MNPs) to produce chromosome damage in human alveolar A549 cells. Compared to control cells, all the applied MNPs increased the level of micronuclei moderately but did not cause structural chromosomal aberrations in exposed cells. A rise in endoreplication, polyploid and multinuclear cells along with disruption of tubulin filaments, downregulation of Aurora protein kinases and p53 protein activation indicated the capacity of these MNPs to impair the chromosomal passenger complex and/or centrosome maturation. We suppose that surface-modified MNPs may act as aneugen-like spindle poisons via interference with tubulin polymerization. Further studies on experimental animals revealing mechanisms of therapeutic-aimed MNPs are required to confirm their suitability as potential anti-cancer drugs.

Biodistribution of negatively charged iron oxide nanoparticles (IONPs) in mice and enhanced brain delivery using lysophosphatidic acid (LPA)

Effective treatment of brain disorders requires a focus on improving drug permeability across the blood-brain barrier (BBB). Herein, we examined the pharmacokinetic properties of negatively charged iron oxide nanoparticles (IONPs) and the capability of using lysophosphatidic acid (LPA) to transiently disrupt the tight junctions and allow IONPs to enter the brain. Under normal conditions, IONPs had a plasma half-life of six minutes, with the liver and spleen being the major organs of deposition. Treatment with LPA enhanced accumulation of IONPs in the brain and spleen (approximately 4-fold vs. control). LPA and IONP treated mice revealed no sign of peripheral immune cell infiltration in the brain and no significant activation of microglia or astrocytes. These studies show improved delivery efficiency of IONPs following LPA administration. Our findings suggest transient disruption of the BBB may be a safe and effective method for increasing IONP delivery to the brain.

Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens)) proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs.

In Vitro/In Vivo Toxicity Evaluation and Quantification of Iron Oxide Nanoparticles

Increasing biomedical applications of iron oxide nanoparticles (IONPs) in academic and commercial settings have alarmed the scientific community about the safety and assessment of toxicity profiles of IONPs. The great amount of diversity found in the cytotoxic measurements of IONPs points toward the necessity of careful characterization and quantification of IONPs. The present document discusses the major developments related to in vitro and in vivo toxicity assessment of IONPs and its relationship with the physicochemical parameters of IONPs. Major discussion is included on the current spectrophotometric and imaging based techniques used for quantifying, and studying the clearance and biodistribution of IONPs. Several invasive and non-invasive quantification techniques along with the pitfalls are discussed in detail. Finally, critical guidelines are provided to optimize the design of IONPs to minimize the toxicity.

Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism's ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the OPEN ACCESS Int. J. Mol. Sci. 2015, 16 23483 transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells.

Engineered metal based nanoparticles and innate immunity

Almost all people in developed countries are exposed to metal nanoparticles (MeNPs) that are used in a large number of applications including medical (for diagnostic and therapeutic purposes). Once inside the body, absorbed by inhalation, contact, ingestion and injection, MeNPs can translocate to tissues and, as any foreign substance, are likely to encounter the innate immunity system that represent a non-specific first line of defense against potential threats to the host. In this review, we will discuss the possible effects of MeNPs on various components of the innate immunity (both specific cells and barriers). Most important is that there are no reports of immune diseases induced by MeNPs exposure: we are operating in a safe area. However, in vitro assays show that MeNPs have some effects on innate immunity, the main being toxicity (both cyto- and genotoxicity) and interference with the activity of various cells through modification of membrane receptors, gene expression and cytokine production. Such effects can have both negative and positive relevant impacts on humans. On the one hand, people exposed to high levels of MeNPs, as workers of industries producing or applying MeNPs, should be monitored for possible health effects. On the other hand, understanding the modality of the effects on immune responses is essential to develop medical applications for MeNPs. Indeed, those MeNPs that are able to stimulate immune cells could be used to develop of new vaccines, promote immunity against tumors and suppress autoimmunity.

Effects of iron oxide nanoparticles: cytotoxicity, genotoxicity, developmental toxicity, and neurotoxicity

Iron oxide nanoparticles (ION) with superparamagnetic properties hold great promise for use in various biomedical applications; specific examples include use as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Increasing potential applications raise concerns over their potential effects on human health. Nevertheless, very little is currently known about the toxicity associated with exposure to these nanoparticles at different levels of biological organization. This article provides an overview of recent studies evaluating ION cytotoxicity, genotoxicity, developmental toxicity and neurotoxicity. Although the results of these studies are sometimes controversial, they generally indicate that surface coatings and particle size seem to be crucial for the observed ION-induced effects, as they are critical determinants of cellular responses and intensity of effects, and influence potential mechanisms of toxicity. The studies also suggest that some ION are safe for certain biomedical applications, while other uses need to be considered more carefully. Overall, the available studies provide insufficient evidence to fully assess the potential risks for human health related to ION exposure. Additional research in this area is required including studies on potential long-term effects.

The role of intracellular redox imbalance in nanomaterial induced cellular damage and genotoxicity: a review

The terms oxidative stress, free radical generation, and intracellular antioxidant protection have become part of everyday nanotoxicology terminology. In recent years, an ever increasing number of in vitro and in vivo studies have implicated disruptions to the redox balance and oxidative stress as one of the main contributors to nanomaterial (NM) induced adverse effects. One of the most important and widely investigated of these effects is genotoxicity. In general, systems that defend an organism against oxidative damage to DNA are very complex and include prevention of reactive oxygen species (ROS) production, neutralizing ROS (scavengers), enzymatic nucleotide pool sanitation, and DNA repair. This review discusses the importance of the maintenance of the redox balance in this context before examining studies that have investigated engineered NM induced redox imbalance and genotoxicity. Furthermore, we identify data gaps, and highlight a number of issues that exist with the methodologies that are routinely utilized to investigate intracellular ROS production or anti-oxidant depletion. We conclude that for a large number of engineered NM types changes in the redox balance toward oxidative stress are normally associated with DNA damage.

The cytotoxicity of gold nanoparticles is dispersity-dependent

Well-dispersed gold nanoparticles show rather good biocompatibility, while aggregated gold nanoparticles with the same dose show considerable cytotoxicity. This result indicates that the dispersity of nanoparticles plays an important role in cytotoxicity.