Cytotoxicity, oxidative stress and inflammation induced by ZnO nanoparticles in endothelial cells: interaction with palmitate or lipopolysaccharide

Exploring novel potential of mycosynthesized magnetic nanoparticles for phosphatase immobilization and biological activity

Among different microbes, fungi are proficient candidates for the extracellular synthesis of iron nanoparticles. For biogenic synthesis of iron nanoparticles, a thermophilic mould Myceliophthora thermophila BJTLRMDU7 was used in this study. Mycogenic magnetic nanoparticles were used for phosphatase immobilization and therapeutic applications such as antimicrobial and antimalarial activity. Firstly, the phosphatase was immobilized on biogenic iron nanoparticles with an efficiency of >56 %. Immobilized enzyme was optimally active at 60 °C and pH 5. Immobilized phosphatase was recycled using external magnetic field up to 4th cycle retaining >50 % activity. The immobilized phosphatase efficiently released inorganic phosphate from different flours such as wheat, maize and gram at 37 °C and 60 °C. There was continuous increase in the release of inorganic phosphorus from all samples with incubation time at 37 °C and slight reduction at 60 °C. These nanoparticles showed the effective antimicrobial activity against Bacillus subtilis, Escherichia coli and Myceliophthora thermophila. Further, the synthesized iron nanoparticles showed antimalarial potential against Plasmodium falciparum. Biogenic nanoparticles did not exhibit hemolytic activity and cytotoxicity. Therefore, biogenic iron nanoparticles could be used as a suitable matrix for immobilization of enzymes and safe therapeutics.

Application of nanoparticles in breast cancer treatment: a systematic review

It is estimated that cancer is the second leading cause of death worldwide. The primary or secondary cause of cancer-related mortality for women is breast cancer. The main treatment method for different types of cancer is chemotherapy with drugs. Because of less water solubility of chemotherapy drugs or their inability to pass through membranes, their body absorbs them inadequately, which lowers the treatment's effectiveness. Drug specificity and pharmacokinetics can be changed by nanotechnology using nanoparticles. Instead, targeted drug delivery allows medications to be delivered to the targeted sites. In this review, we focused on nanoparticles as carriers in targeted drug delivery, their characteristics, structure, and the previous studies related to breast cancer. It was shown that nanoparticles could reduce the negative effects of chemotherapy drugs while increasing their effectiveness. Lipid-based nanocarriers demonstrated notable results in this instance, and some products that are undergoing various stages of clinical trials are among the examples. Nanoparticles based on metal or polymers demonstrated a comparable level of efficacy. With the number of cancer cases rising globally, many researchers are now looking into novel treatment approaches, particularly the use of nanotechnology and nanoparticles in the treatment of cancer. In order to help clinicians, this article aimed to gather more information about various areas of nanoparticle application in breast cancer therapy, such as modifying their synthesis and physicochemical characterization. It also sought to gain a deeper understanding of the mechanisms underlying the interactions between nanoparticles and biologically normal or infected tissues.

pH-Sensitive doxorubicin delivery using zinc oxide nanoparticles as a rectified theranostic platform: in vitro anti-proliferative, apoptotic, cell cycle arrest and in vivo radio-distribution studies

Despite enormous advancements in its management, cancer is the world's primary cause of mortality. Therefore, tremendous strides were made to produce intelligent theranostics with mitigated side effects and improved specificity and efficiency. Thus, we developed a pH-sensitive theranostic platform composed of dextran immobilized zinc oxide nanoparticles, loaded with doxorubicin and radiolabeled with the technetium-99m radionuclide (99mTc-labelled DOX-loaded ZnO@dextran). The platform measured 11.5 nm in diameter with -12 mV zeta potential, 88% DOX loading efficiency and 98.5% radiolabeling efficiency. It showed DOX release in a pH-responsive manner, releasing 93.1% cumulatively at pH 5 but just 7% at pH 7.4. It showed improved intracellular uptake, which resulted in a high growth suppressive effect against MCF-7 cancer cells as compared to the free DOX. It boasted a 4 times lower IC50 than DOX, indicating its significant anti-proliferative potential (0.14 and 0.55 μg ml-1, respectively). The in vitro biological evaluation revealed that its molecular mode of anti-proliferative action included downregulating Cdk-2, which provoked G1/S cell cycle arrest, and upregulating both the intracellular ROS level and caspase-3, which induced apoptosis and necrosis. The in vivo experiments in Ehrlich-ascites carcinoma bearing mice demonstrated that DOX-loaded ZnO@dextran showed a considerable 4-fold increase in anti-tumor efficacy compared to DOX. Moreover, by utilizing the diagnostic radionuclide (99mTc), the radiolabeled platform (99mTc-labelled DOX-loaded ZnO@dextran) was in vivo monitored in tumor-bearing mice, revealing high tumor accumulation (14% ID g-1 at 1 h p.i.) and reduced uptake in non-target organs with a 17.5 T/NT ratio at 1 h p.i. Hence, 99mTc-labelled DOX-loaded ZnO@dextran could be recommended as a rectified tumor-targeted theranostic platform.

ZnO based 0-3D diverse nano-architectures, films and coatings for biomedical applications

Thin-film nano-architecting is a promising approach that controls the properties of nanoscale surfaces to increase their interdisciplinary applications in a variety of fields. In this context, zinc oxide (ZnO)-based various nano-architectures (0-3D) such as quantum dots, nanorods/nanotubes, nanothin films, tetrapods, nanoflowers, hollow structures, etc. have been extensively researched by the scientific community in the past decade. Owing to its unique surface charge transport properties, optoelectronic properties and reported biomedical applications, ZnO has been considered as one of the most important futuristic bio-nanomaterials. This review is focused on the design/synthesis and engineering of 0-3D nano-architecture ZnO-based thin films and coatings with tunable characteristics for multifunctional biomedical applications. Although ZnO has been extensively researched, ZnO thin films composed of 0-3D nanoarchitectures with promising thin film device bio-nanotechnology applications have rarely been reviewed. The current review focuses on important details about the technologies used to make ZnO-based thin films, as well as the customization of properties related to bioactivities, characterization, and device fabrication for modern biomedical uses that are relevant. It features biosensing, tissue engineering/wound healing, antibacterial, antiviral, and anticancer activity, as well as biomedical diagnosis and therapy with an emphasis on a better understanding of the mechanisms of action. Eventually, key issues, experimental parameters and factors, open challenges, etc. in thin film device fabrications and applications, and future prospects will be discussed, followed by a summary and conclusion.

Food-grade titanium dioxide (E171) and zinc oxide nanoparticles induce mitochondrial permeability and cardiac damage after oral exposure in rats

Food-grade titanium dioxide (E171) and zinc oxide nanoparticles (ZnO NPs) are found in diverse products for human use. E171 is used as whitening agent in food and cosmetics, and ZnO NPs in food packaging. Their potential multi-organ toxicity has raised concerns on their safety. Since mitochondrial dysfunction is a key aspect of cardio-pathologies, here, we evaluate the effect of chronic exposure to E171 and ZnO NPs in rats on cardiac mitochondria. Changes in cardiac electrophysiology and body weight were measured. E171 reduced body weight more than 10% after 5 weeks. Both E171 and ZnO NPs increased systolic blood pressure (SBP) from 110-120 to 120-140 mmHg after 45 days of treatment. Both NPs altered the mitochondrial permeability transition pore (mPTP), reducing calcium requirement for permeability by 60% and 93% in E171- and ZnO NPs-exposed rats, respectively. Treatments also affected conformational state of adenine nucleotide translocase (ANT). E171 reduced the binding of EMA to Cys 159 in 30% and ZnO NPs in 57%. Mitochondrial aconitase activity was reduced by roughly 50% with both NPs, indicating oxidative stress. Transmission electron microscopy (TEM) revealed changes in mitochondrial morphology including sarcomere discontinuity, edema, and hypertrophy in rats exposed to both NPs. In conclusion, chronic oral exposure to NPs induces functional and morphological damage in cardiac mitochondria, with ZnO NPs being more toxic than E171, possibly due to their dissociation in free Zn2+ ion form. Therefore, chronic intake of these food additives could increase risk of cardiovascular disease.

Green synthesis of iron nanoparticles: Sources and multifarious biotechnological applications

Green synthesis of iron nanoparticles is a highly fascinating research area and has gained importance due to reliable, sustainable and ecofriendly protocol for synthesizing nanoparticles, along with the easy availability of plant materials and their pharmacological significance. As an alternate to physical and chemical synthesis, the biological materials, like microorganisms and plants are considered to be less costly and environment-friendly. Iron nanoparticles with diverse morphology and size have been synthesized using biological extracts. Microbial (bacteria, fungi, algae etc.) and plant extracts have been employed in green synthesis of iron nanoparticles due to the presence of various metabolites and biomolecules. Physical and biochemical properties of biologically synthesized iron nanoparticles are superior to that are synthesized using physical and chemical agents. Iron nanoparticles have magnetic property with thermal and electrical conductivity. Iron nanoparticles below a certain size (generally 10-20 nm), can exhibit a unique form of magnetism called superparamagnetism. They are non-toxic and highly dispersible with targeted delivery, which are suitable for efficient drug delivery to the target. Green synthesized iron nanoparticles have been explored for multifarious biotechnological applications. These iron nanoparticles exhibited antimicrobial and anticancerous properties. Iron nanoparticles adversely affect the cell viability, division and metabolic activity. Iron nanoparticles have been used in the purification and immobilization of various enzymes/proteins. Iron nanoparticles have shown potential in bioremediation of various organic and inorganic pollutants. This review describes various biological sources used in the green synthesis of iron nanoparticles and their potential applications in biotechnology, diagnostics and mitigation of environmental pollutants.

Influences of lysine-specific demethylase 1 inhibitors on NO synthase-Kruppel-like factor pathways in human endothelial cells in vitro and zebrafish (Danio rerio) larvae in vivo

Lysine-specific demethylase 1 (LSD1) inhibitors are being developed for cancer therapy, but their bioeffects on vasculatures are not clear. In this study, we compared the influences of ORY-1001 (an LSD1 inhibitor being advanced into clinical trials) and 199 (a novel LSD1 inhibitor recently developed by us) to human umbilical vein endothelial cells (HUVECs) in vitro and further verified the bioeffects of ORY-1001 to zebrafish (Danio rerio) larvae in vivo. The results showed that up to 10 μM ORY-1001 or 199 did not significantly affect the cellular viability of HUVECs but substantially reduced the release of inflammatory interleukin-8 (IL-8) and IL-6. The signaling molecule in vasculatures, NO, was also increased in HUVECs. As the mechanism, the protein levels of endothelial NO synthase (eNOS) or p-eNOS, and their regulators Kruppel-like factor 2 (KLF2) or KLF4, were also increased after drug treatment. In vivo, 24 h treatment with up to 100 nM ORY-1001 reduced blood speed without changing morphologies or locomotor activities in zebrafish larvae. ORY-1001 treatment reduced the expression of il8 but promoted the expression of klf2a and nos in the zebrafish model. These data show that LSD1 inhibitors were not toxic but capable to inhibit inflammatory responses and affect the function of blood vessels through the up-regulation of the NOS-KLF pathway.

Iron Nanoparticles Open Up New Directions for Promoting Healing in Chronic Wounds in the Context of Bacterial Infection

Metal nanoparticles play an outstanding role in the field of wound healing due to their excellent properties, and the significance of iron, one of the most widely used metals globally, cannot be overlooked. The purpose of this review is to determine the importance of iron nanoparticles in wound-healing dressings. Prolonged, poorly healing wounds may induce infections; wound infections are a major cause of chronic wound formation. The primary components of iron nanoparticles are iron oxide nanoparticles, which promote wound healing by being antibacterial, releasing metal ions, and overcoming bacterial resistance. The diameter of iron oxide nanoparticles typically ranges between 1 and 100 nm. Magnetic nanoparticles with a diameter of less than 30 nm are superparamagnetic and are referred to as superparamagnetic iron oxide nanoparticles. This subset of iron oxide nanoparticles can use an external magnetic field for novel functions such as magnetization and functionalization. Iron nanoparticles can serve clinical purposes not only to enhance wound healing through the aforementioned means but also to ameliorate anemia and glucose irregularities, capitalizing on iron's properties. Iron nanoparticles positively impact the healing process of chronic wounds, potentially extending beyond wound management.

Recent advances in molecular biology of metabolic syndrome pathophysiology: endothelial dysfunction as a potential therapeutic target

Current advances in molecular pathobiology of endotheliocytes dysfunctions are promising in finding the pathogenetic links to the emergence of insulin resistance syndrome. Physiologically, human organism homeostasis is strictly controlled to maintain metabolic processes at the acquainted level. Many factors are involved in maintaining these physiological processes in the organism and any deviation is undoubtedly accompanied by specific pathologies related to the affected process. Fortunately, the body’s defense system can solve and compensate for the impaired function through its multi-level defense mechanisms. The endothelium is essential in maintaining this homeostasis through its ability to modulate the metabolic processes of the organism. Pathological activity or impairment of physiological endothelium function seems directly correlated to the emergence of metabolic syndrome. The most accepted hypothesis is that endothelium distribution is due to endoplasmic reticulum stress and unfolded protein response development, which includes inhibition of long non-coding RNAs expression, cytokines disbalance, Apelin dysregulation, glycocalyx degradation, and specific microparticles. Clinically, the enhancement or restoration of normal endothelial cells can be a target for novel therapeutic strategies since the distribution of its physiological activity impairs homeostasis and results in the progression of metabolic syndrome, and induction of its physiological activity can ameliorate insulin resistance syndrome. Novel insights on the molecular mechanisms of endothelial cell dysfunction are concisely represented in this paper to enhance the present therapeutic tactics and advance the research forward to find new therapeutic targets.

Ag2O Nanoparticles as a Candidate for Antimicrobial Compounds of the New Generation

Antibiotic resistance in microorganisms is an important problem of modern medicine which can be solved by searching for antimicrobial preparations of the new generation. Nanoparticles (NPs) of metals and their oxides are the most promising candidates for the role of such preparations. In the last few years, the number of studies devoted to the antimicrobial properties of silver oxide NPs have been actively growing. Although the total number of such studies is still not very high, it is quickly increasing. Advantages of silver oxide NPs are the relative easiness of production, low cost, high antibacterial and antifungal activities and low cytotoxicity to eukaryotic cells. This review intends to provide readers with the latest information about the antimicrobial properties of silver oxide NPs: sensitive organisms, mechanisms of action on microorganisms and further prospects for improving the antimicrobial properties.

Nutrient molecule corona: An update for nanomaterial-food component interactions

The adsorption of biological molecules to nanomaterials (NMs) will significantly impact NMs' behavior in complex microenvironments. Previously we proposed the need to consider the interactions between food components and NMs for the evaluation of oral toxicity of NMs. This review updated this concept as nutrient molecule corona, that the adsorption of nutrient molecules alters the uptake of nutrient molecules and/or NMs, as well as the signaling pathways to induce a combined toxicity due to the biologically active nature of nutrient molecules. Even with the presence of protein corona, nutrient molecules may still bind to NMs to change the identities of NMs in vivo. Furthermore, this review proposed the binding of excessive nutrient molecules to NMs to induce a combined toxicity under pathological conditions such as metabolic diseases. The structures of nutrient molecules and physicochemical properties of NMs determine nutrient molecule corona formation, and these aspects should be considered to limit the unwanted effects brought by nutrient molecule corona. In conclusion, similar to other biological molecule corona, the formation of nutrient molecule corona due to the presence of food components or excessive nutrient molecules in pathophysiological microenvironments will alter the behaviors of NMs.

Meta-analysis of in-vitro cytotoxicity evaluation studies of zinc oxide nanoparticles: Paving way for safer innovations

Nano-based products have shown their daunting presence in several sectors. Among them, Zinc Oxide (ZnO) nanoparticles wangled the reputation of providing "next-generation solutions" and are being utilized in plethora of products. Their widespread application has led to increased exposure of these particles, raising concerns regarding toxicological repercussions to the human health and environment. The diversity, complexity, and heterogeneity in the available literature, along with correlation of befitting attributes, makes it challenging to develop one systematic framework to predict this toxicity. The present study aims at developing predictive modelling framework to tap the prospective features responsible for causing cytotoxicity in-vitro on exposure to ZnO nanoparticles. Rigorous approach was used to mine the information from complete body of evidence published to date. The attributes, features and experimental conditions were systematically extracted to unmask the effect of varied features. 1240 data points from 76 publications were obtained, containing 14 qualitative and quantitative attributes, including physiochemical properties of nanoparticles, cell culture and experimental parameters to perform meta-analysis. For the first time, the efforts were made to investigate the degree of significance of attributes accountable for causing cytotoxicity on exposure to ZnO nanoparticles. We show that in-vitro cytotoxicity is closely related with dose concentration of nanoparticles, followed by exposure time, disease state of the cell line and size of these nanoparticles among other attributes.

Preparation of Cotton-Zinc Composites by Magnetron Sputtering Metallization and Evaluation of their Antimicrobial Properties and Cytotoxicity

The aim of this investigation was to evaluate the biological properties of cotton-zinc composites. A coating of zinc (Zn) on a cotton fabric was successfully obtained by a DC magnetron sputtering system using a metallic Zn target (99.9%). The new composite was characterized using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), UV/Vis transmittance, and atomic absorption spectrometry with flame excitation (FAAS). The composite was tested for microbial activity against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and antifungal activity against Aspergillus niger and Chaetomium globosum fungal mold species as model microorganisms. Cytotoxicity screening of the tested modified material was carried out on BALB/3T3 clone mouse fibroblasts. The SEM/EDS and FAAS tests showed good uniformity of zinc content on a large surface of the composite. The conducted research showed the possibility of using the magnetron sputtering technique as a zero-waste method for producing antimicrobial textile composites.

Fabrication of phenyl boronic acid modified pH-responsive zinc oxide nanoparticles as targeted delivery of chrysin on human A549 cells

Recently, different natural bioactive compounds have been used as anticancer agents for their various therapeutic benefits and non-toxic nature to other organs. However, they have various restrictions in preclinical and clinical studies due to their non-targeting nature and insufficient bioavailability. As a result, a zinc oxide nanoparticle (ZnO) based drug delivery medium was constructed which has good bio-compatibility and bio-degradability. It also displays cancer cell-specific drug delivery in a targeted and controlled way. In the present study, phenylboronic acid (PBA) tagged ZnO nanoparticles (ZnO-PBA) was fabricated and in the next step, chrysin (a natural bio-active molecule) was loaded to it to form the nanoconjugate (ZnO-PBA-Chry). Different characterization techniques were used to confirm the successful fabrication of ZnO-PBA-Chry. PBA-tagging to the nanoparticle helps in targeted delivery of chrysin in lung cancer cells (A549) as PBA binds with sialic acid receptors which are over-expressed on the surface of A549 cells. As ZnO dissociates in acidic pH, it shows stimuli-responsive release of chrysin in tumor microenvironment. Application of ZnO-PBA-Chry nanohybrid in lung cancer cell line A549 caused oxidative stress mediated intrinsic cell death and cell cycle arrest. ZnO-PBA-Chry downregulated MMP-2 and VE-Cadherin, thereby inhibiting metastasis and the invasive property of A549 cells.

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pH-responsive PBA functionalized ZnO nanoparticle was fabricated.

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Chrysin was loaded as a bioactive anticancer agent into ZnO nanoparticle.

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ZnO-PBA-Chry induced intrinsic cell death and cell cycle arrest in A549 cells.

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It inhibited metastasis and invasive properties of A549 cells.

Transcriptomic-based toxicological investigations of graphene oxide with modest cytotoxicity to human umbilical vein endothelial cells: changes of Toll-like receptor signaling pathways

The wide uses of graphene oxide (GO) lead to the contact of GO with vascular systems, so it is necessary to investigate the toxicological effects of GO to endothelial cells. Recently, we reported that GO of small lateral size (<500 nm) was relatively biocompatible to human umbilical vein endothelial cells (HUVECs), but recent studies by using omics-techniques revealed that nanomaterials (NMs) even without acute cytotoxicity might induce other toxicological effects. This study investigated the effects of GO on HUVECs based on RNA-sequencing and bioinformatics analysis. Even after exposure to 100 μg/ml GO, the cellular viability of HUVECs was higher than 70%. Furthermore, 25 μg/ml GO was internalized but did not induce ultrastructural changes or intracellular superoxide. These results combined indicated GO's relatively high biocompatibility. However, by analyzing the most significantly altered Gene Ontology terms and Kyoto Encyclopedia of Gene and Genomes pathways, we found that 25 μg/ml GO altered pathways related to immune systems' functions and the responses to virus. We further verified that GO exposure significantly decreased Toll-like receptor 3 and interleukin 8 proteins, indicating an immune suppressive effect. However, THP-1 monocyte adhesion was induced by GO with or without the presence of inflammatory stimulus lipopolysaccharide. We concluded that GO might inhibit the immune responses to virus in endothelial cells at least partially mediated by the inhibition of TLR3. Our results also highlighted a need to investigate the toxicological effects of NMs even without acute cytotoxicity by omics-based techniques.

Exposure to zinc oxide nanoparticles (ZnO-NPs) induces cardiovascular toxicity and exacerbates pathogenesis - Role of oxidative stress and MAPK signaling

The precise toxico-pathogenic effects of zinc oxide nanoparticles (ZnO-NPs) on the cardiovascular system under normal and cardiovascular disease (CVD) risk factor milieu are unclear. In this study, we have investigated the dose-dependent effects of ZnO-NPs on developing chicken embryo and cell culture (H9c2 cardiomyoblast, HUVEC and aortic VSMC) models. In addition, the potentiation effect of ZnO-NPs on simulated risk factor conditions was evaluated using; 1. Reactive oxygen species (ROS) induced cardiac remodeling, 2. Angiotensin-II induced cardiac hypertrophy, 3. TNF-α induced HUVEC cell death and 4. Inorganic phosphate (Pi) induced aortic VSMC calcification models. The observed results illustrates that ZnO-NPs exposure down regulates vascular development and elevates oxidative stress in heart tissue. At the cellular level, ZnO-NPs exposure reduced the cell viability and increased the intracellular ROS generation, lipid peroxidation and caspase-3 activity in a dose-dependent manner in all three cell types. In addition, ZnO-NPs exposure significantly suppressed the endothelial nitric oxide (NO) generation, cardiac Ca²⁺ - ATPase activity and enhanced the cardiac mitochondrial swelling. Moreover, inhibition of p38 MAPK and JNK signaling pathways influence the cytotoxicity. Overall, ZnO-NPs exposure affects the cardiovascular system under normal conditions and it exacerbates the cardiovascular pathogenesis under selected risk factor milieu.

Advances in smart delivery of food bioactive compounds using stimuli-responsive carriers: Responsive mechanism, contemporary challenges, and prospects

Many important food bioactive compounds are plant secondary metabolites that have traditional applications for health promotion and disease prevention. However, the chemical instability and poor bioavailability of these compounds represent major challenges to researchers. In the last decade, therefore, major impetus has been given for the research and development of advanced carrier systems for the delivery of natural bioactive molecules. Among them, stimuli-responsive carriers hold great promise for simultaneously improving stability, bioavailability, and more importantly delivery and on-demand release of intact bioactive phytochemicals to target sites in response to certain stimuli or combination of them (e.g., pH, temperature, oxidant, enzyme, and irradiation) that would eventually enhance therapeutic outcomes and reduce side effects. Hybrid formulations (e.g., inorganic-organic complexes) and multi-stimuli-responsive formulations have demonstrated great potential for future studies. Therefore, this review systematically compiles and assesses the recent advances on the smart delivery of food bioactive compounds, particularly quercetin, curcumin, and resveratrol through stimuli-responsive carriers, and critically reviews their functionality, underlying triggered-release mechanism, and therapeutic potential. Finally, major limitations, contemporary challenges, and possible solutions/future research directions are highlighted. Much more research is needed to optimize the processing parameters of existing formulations and to develop novel ones for lead food bioactive compounds to facilitate their food and nutraceutical applications.

Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties?

The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.

Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties?

The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.

Induced pluripotent stem cell-derived vascular networks to screen nano-bio interactions

The vascular bioactivity/safety of nanomaterials is typically evaluated by animal testing, which is of low throughput and does not account for biological differences between animals and humans such as ageing, metabolism and disease profiles. The development of personalized human in vitro platforms to evaluate the interaction of nanomaterials with the vascular system would be important for both therapeutic and regenerative medicine. A library of 30 nanoparticle (NP) formulations, in use in imaging, antimicrobial and pharmaceutical applications, was evaluated in a reporter zebrafish model of vasculogenesis and then tested in personalized humanized models composed of human-induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs) with "young" and "aged" phenotypes in 3 vascular network formats: 2D (in polystyrene dish), 3D (in Matrigel) and in a blood vessel on a chip. As a proof of concept, vascular toxicity was used as the main readout. The results show that the toxicity profile of NPs to hiPSC-ECs was dependent on the "age" of the endothelial cells and vascular network format. hiPSC-ECs were less susceptible to the cytotoxicity effect of NPs when cultured in flow than in static conditions, the protective effect being mediated, at least in part, by glycocalyx. Overall, the results presented here highlight the relevance of in vitro hiPSC-derived vascular systems to screen vascular nanomaterial interactions.

Comparison of cytotoxicity of Ag/ZnO and Ag@ZnO nanocomplexes to human umbilical vein endothelial cells in vitro

Novel metal and metal oxide-based nanocomplexes are being developed due to their superior properties compared with nanoparticles (NPs) based on single composition. In this study, we synthesized Ag-coated ZnO (Ag/ZnO) and Ag-doped ZnO (Ag@ZnO) NPs. The cytotoxicity and mechanisms associated with the synthesized NPs were investigated to understand the influence of Ag positions on biocompatibility of the NPs. After exposure to human umbilical vein endothelial cells (HUVECs), Ag/ZnO, Ag@ZnO, and ZnO NPs all significantly induced cytotoxicity, but the cytotoxic effects of Ag/ZnO and Ag@ZnO NPs were more modest in comparison with ZnO NPs. At cytotoxic concentrations, all NPs significantly induced intracellular Zn ions, which suggested a role of excessive Zn ions on cytotoxicity of NPs. All types of NPs significantly induced the expression of endoplasmic reticulum (ER) stress genes including DNA damage-inducible transcript 3 (DDIT3), X-box binding protein 1 (XBP-1), and ER to nucleus signaling 1 (ERN1), but Ag/ZnO and Ag@ZnO NPs were less effective to induce DDIT3 and XBP-1 expression compared with ZnO NPs. Not surprisingly, only ZnO NPs significantly induced the expression of caspase 3. Combined, the results from this study showed that Ag/ZnO and Ag@ZnO NPs were less cytotoxic and less potent to induce ER stress gene expression compared with ZnO NPs, but there were no significant differences between Ag/ZnO and Ag@ZnO NPs. Our results may provide novel understanding about the biocompatibility of Ag-ZnO nanocomplexes.

The investigation of the parameters affecting the ZnO nanoparticle cytotoxicity behaviour: a tutorial review

In the last 30 years the research about zinc oxide nanoparticles (ZnO NPs) and their related toxicity has shown a boom. ZnO NPs show cytotoxicity for both prokaryotic and eukaryotic cells and many studies demonstrated their selective toxicity towards cancer cells. However, with the increasing number of publications, it is observed an increase in the discrepancies obtained between the various results. Soon the scientific community understood that the ZnO NC toxicity behaviour is affected by many factors, related not only to the ZnO NPs themselves, but also to the experimental conditions used. Many recent reviews discussed these parameters by reporting experimental evidence and tried to assess the general statements about the ZnO NP cytotoxicity. This information is extremely useful for the evaluation of which type of ZnO NPs is more or less suitable for a specific study or application. However, despite that, a deep comprehension of the ZnO NP behaviour in relation to the different experimental conditions is still lacking. Actually, a full understanding of the reasons behind the NP behaviour is essential to better assess their biological activity and in particular their therapeutic application, avoiding undesired effects both in the experimental and clinical contexts. This tutorial review aims to be an experimental and practical guide for scientists that faced with the use of ZnO NPs for biomedical applications and, in particular, for their therapeutic purposes. The driving idea is to not simply summarize the results reported in the literature, but to provide instruments for a deep comprehension of the mechanisms affecting the ZnO NP cytotoxicity and behavior. This review also aims to point out the critical experimental parameters to be considered when working with these NPs, as well as the main related risks and limitations that scientists have to face.

Assessment of Amphiphilic Poly-N-vinylpyrrolidone Nanoparticles' Biocompatibility with Endothelial Cells in Vitro and Delivery of an Anti-Inflammatory Drug

Nanoparticles (NPs) produced from amphiphilic derivatives of poly-N-vinylpyrrolidone (Amph-PVP), composed of various molecular weight polymeric hydrophilic fragments linked into hydrophobic n-alkyl chains of varying lengths, were previously shown to exert excellent biocompatibility. Although routes of administration can be different, finally, most nanosystems enter the blood circulation or lymphatic vessels, and by this, they establish direct contact with endothelial cells. In this study, Amph-PVP NPs and fluorescently labeled Amph-PVP-based NPs, namely "PVP" NPs (Amph-PVP-NPs (6000 Da) unloaded) and "F"-NPs (Amph-PVP-NPs (6000 Da) loaded with fluorescent FITC), were synthesized to study Amph-PVP NPs interactions with HMEC-1 endothelial cells. PVP NPs were readily uptaken by HMEC-1 cells in a concentration-dependent manner, as demonstrated by immunofluorescence imaging. Upon uptake, the FITC dye was localized to the perinuclear region and cytoplasm of treated cells. The generation of lipopolysaccharide (LPS)-induced activated endothelium model revealed an increased uptake of PVPNPs, as shown by confocal microscopy. Both unloaded PVP NPs and F-NPs did not affect EC viability in the 0.01 to 0.066 mg/mL range. Furthermore, we focused on the potential immunological activation of HMEC-1 endothelial cells upon PVPNPs treatment by assessing the expression of their E-Selectin, ICAM-1, and VCAM-1 adhesion receptors. None of the adhesion molecules were affected by NP treatments of both activated by LPS and nonactivated HMEC-1 cells, at the utilized concentrations (p = NS). In this study, PVP (6000 Da) NPs were used to encapsulate indomethacin, a widely used anti-inflammatory drug. The synthesized drug carrier complex did not affect HMEC-1 cell growth and expression of E-selectin, ICAM-1, and VCAM-1 adhesion receptors. In summary, PVP-based NPs are safe for use on both basal and activated endothelium, which more accurately mimics pathological conditions. Amph-PVP NPs are a promising drug delivery system.

Structure and Properties of ZnO Coatings Obtained by Atomic Layer Deposition (ALD) Method on a Cr-Ni-Mo Steel Substrate Type

This paper aimed to investigate the structure and physicochemical and tribological properties of ZnO coatings deposited by ALD on 316L stainless steel for biomedical applications. To obtain ZnO films, diethylzinc (DEZ) and water were used as ALD precursors. Zinc oxide layers were deposited at the same temperature of 200 °C using three types of ALD cycles: 500, 1000 and 1500. The structure and morphology of ZnO coatings were examined using SEM and AFM microscopes. The XRD and GIXRD methods were used for the phase analysis of the obtained coatings. To determine the resistance to pitting corrosion, potentiodynamic investigations and impedance spectroscopy were conducted in a Ringer solution at a temperature of 37 °C. The obtained results showed that the number of ALD cycles had a significant impact on the structure, morphology and corrosion resistance of the ZnO layers. It was found that after increasing the coating thickness of the ZnO on the material, its electrochemical properties determining the corrosion resistance also increased. Moreover, on the basis of the ball-on-plate tribological investigations, we found a significant reduction in the friction coefficient of the samples with the investigated coatings in relation to the noncoated substrates.

Nanoparticles retard immune cells recruitment in vivo by inhibiting chemokine expression

The large-scale utilization of nanotechnology depends on public and consumer confidence in the safety of this new technology. Studying the interaction of nanoparticles with immune cells plays a vital role in the safety assessment of nanomedicine. Although some researches have indicated that the immune cells undergo severe interfere after phagocytosis of nanoparticles, the impact on immune system of the whole body are still unclear. Here, we use immune cells labeled transgenic zebrafish to study the mechanisms of nanoparticles on zebrafish immune cells. We demonstrate that gold nanoparticles (Au NPs) phagocytized by immune cells can reduce and retard the sensitivity of immune response, resulting nanoparticle-induced bluntness in immune cell (NIBIC). RNA-seq and functional analysis reveal that NIBIC is mainly induced by the inhibiting expression of chemokine receptor 5 (CCR5). Furthermore, PVP-modified Au NPs can eliminate NIBIC by inhibiting the cell phagocytosis. Our results highlight the potential risk for Au NPs in vivo and further the understanding of the mechanism of the interaction between Au NPs and the immune response. We should consider this factor in future material design and pay more attention to the process of using nanomedicines on immune diseases.

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.

Oxidative stress-mediated genotoxic effect of zinc oxide nanoparticles on Deinococcus radiodurans

Extensive use of nanomaterials in consumer products has invoked the concerns about interactions of nanoparticles with living organisms (including microorganisms). Zinc oxide nanoparticles (ZnO NPs) are well known for their antibacterial effect due to reactive oxygen species (ROS) generation. Therefore, their release into the environment is expected to raise major concern towards ecotoxicity. In the present study, we have studied the toxic effect of ZnO NPs on Deinococcus radiodurans, which is well known to show extraordinary resistant from the damaging effects of radiation. Result showed that ZnO NPs are significantly internalized into the bacterial cells and induce concentration-dependent toxicity with membrane damage. Genotoxicity studies revealed that ZnO exposure induces significant DNA damage to bacterial cells. All the observations evidenced that ZnO NPs induce significant ROS generation, protein oxidation and DNA damage with concomitant thiol depletion. Further, gene expression analysis showed that several DNA repair genes and metabolic pathway-related genes are downregulated upon ZnO NP exposure, with simultaneous increase in the expression of DNA damage response genes. Thus, the present study on toxicity of ZnO NPs on a model organism, D. radiodurans, inflicts the possible mechanism behind ZnO NP-mediated toxic effects on various other microbial organisms.

Protein and lipid homeostasis altered in rat macrophages after exposure to metallic oxide nanoparticles

Metal oxide nanoparticles (NPs), such as ZnO, ZnFe₂O₄, and Fe₂O₃, are widely used in industry. However, little is known about the cellular pathways involved in their potential toxicity. Here, we particularly investigated the key molecular pathways that are switched on after exposure to sub-toxic doses of ZnO, ZnFe₂O₄, and Fe₂O₃ in the in vitro rat alveolar macrophages (NR8383). As in our model, the calculated IC₅₀ were respectively 16, 68, and more than 200 μg/mL for ZnO, ZnFe₂O₄, and Fe₂O₃; global gene and protein expression profiles were only analyzed after exposure to ZnO and ZnFe₂O₄ NPs. Using a rat genome microarray technology, we found that 985 and 1209 genes were significantly differentially expressed in NR8383 upon 4 h exposure to ¼ IC₅₀ of ZnO and ZnFe₂O₄ NPs, respectively. It is noteworthy that metallothioneins were overexpressed genes following exposure to both NPs. Moreover, Ingenuity Pathway Analysis revealed that the top canonical pathway disturbed in NR8383 exposed to ZnO and ZnFe₂O₄ NPs was eIF2 signaling involved in protein homeostasis. Quantitative mass spectrometry approach performed from both NR8383 cell extracts and culture supernatant indicated that 348 and 795 proteins were differentially expressed upon 24 h exposure to ¼ IC₅₀ of ZnO and ZnFe₂O₄ NPs, respectively. Bioinformatics analysis revealed that the top canonical pathways disturbed in NR8383 were involved in protein homeostasis and cholesterol biosynthesis for both exposure conditions. While VEGF signaling was specific to ZnO exposure, iron homeostasis signaling pathway was specific to ZnFe₂O₄ NPs. Overall, the study provides resource of transcriptional and proteomic markers of response to ZnO and ZnFe₂O₄ NP-induced toxicity through combined transcriptomics, proteomics, and bioinformatics approaches.

Targeted delivery of quercetin via pH-responsive zinc oxide nanoparticles for breast cancer therapy

Naturally occurring bioactive compounds are gaining much importance as anti-tumor agents in recent times due to their high therapeutic potential and less systemic toxicity. However, different preclinical and clinical studies have noted significant shortcomings, such as nonspecific tumor targeting and low bioavailability which limit their usage in therapeutics. Therefore, a safe and compatible nanoparticle mediated controlled drug delivery system is in high demand to enable effective transport of the drug candidates in the tumor tissue. Herein, we have synthesized phenylboronic acid (PBA) conjugated Zinc oxide nanoparticles (PBA-ZnO), loaded with quercetin (a bioflavonoid widely found in plants), with zeta potential around -10.2 mV and diameter below 40 nm. Presence of PBA moieties over the nanoparticle surface facilitates targeted delivery of quercetin to the sialic acid over-expressed cancer cells. Moreover, Quercetin loaded PBA-ZnO nanoparticles (denoted as PBA-ZnO-Q) showed pH responsive drug release behavior. Results suggested that PBA-ZnO-Q induced apoptotic cell death in human breast cancer cells (MCF-7) via enhanced oxidative stress and mitochondrial damage. In line with the in vitro results, PBA-ZnO-Q was found to be effective in reducing tumor growth in EAC tumor bearing mice. Most interestingly, PBA-ZnO-Q is found to reduce tumor associated toxicity in liver, kidney and spleen. The cytotoxic potential of the nanohybrid is attributed to the combinatorial cytotoxic effects of quercetin and ZnO in the cancer cells. Overall, the presented data highlighted the chemotherapeutic potential of the novel nanohybrid, PBA-ZnO-Q which can be considered for clinical cancer treatment.

Assessment of the structural reorganization of liver and biochemical parameters of blood serum after introduction of zinc nanoparticles and its oxides

The demand for nanoparticles of metals and their oxides in medicine and biology is indisputable. To ensure the safe use of the unique capabilities of nanostructures, in particular, essential metals and their oxides, and to further search for ways leveling side effects of toxic effects in biomedical applications, a multifaceted approach to the study of their properties is needed, primarily affecting the effects on the organism level. In this connection, the purpose of the present research was to study the effect of zinc nanoparticles (ZnNPs) and zinc oxide nanoparticles (ZnONPs) on structural reorganization of the liver and morpho-biochemical parameters of rat blood. The test substances exhibit a hepatotoxic effect upon their single intraperitoneal administration to rats. In the experiment, increased activity of gamma glutamyltransferase (GGT) and lactate dehydrogenase (LDH), increased expression of caspase-3, the presence of signs of oxidative stress, inflammation, and capillary-trophic insufficiency, and induction of tumor necrosis factor (TNF-α), and colony stimulating factor 2 (granulocyte-macrophage) (GM-CSF) were registered in the experiment. The level of interferon-γ in the experimental groups tended to decrease in comparison with the control group. The observed effects progressed in time, most noticeably manifested in the case of ZnONPs. Comparing the dosages, ZnNPs are less toxic than ZnONPs.

A comparative study of toxicity of TiO2, ZnO, and Ag nanoparticles to human aortic smooth-muscle cells

PURPOSE

To evaluate the adverse vascular effects of nanoparticles (NPs) in vitro, extensive studies have investigated the toxicity of NPs on endothelial cells, but the knowledge of potential toxicity on human smooth-muscle cells (SMCs) is currently limited.

METHODS

This study compared the toxicity of TiO2, ZnO, and Ag NPs to human aortic SMCs.

RESULTS

Only ZnO NPs significantly induced cytotoxicity, accompanied by increased intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress biomarkers (DDIT3 expression and p-Chop proteins). All the NPs significantly promoted the release of soluble VCAM1 and soluble sICAM1, but not IL6, which suggested that metal-based NPs might promote inflammatory responses. Furthermore, KLF4 expression (a transcription factor for SMC-phenotype switch) was significantly induced by TiO2 NPs and modestly by ZnO NPs, but the expression of CD68 remained unaltered.

CONCLUSION

Our data indicated that ZnO NPs were more cytotoxic to human aortic SMCs than TiO2 and Ag NPs at the same mass concentrations, which might have been associated with intracellular reactive oxygen species, Zn ions, and endoplasmic reticulum stress.

3-Hydroxyflavone enhances the toxicity of ZnO nanoparticles in vitro

It is recently shown that flavonoids might reduce the toxicity of nanoparticles (NPs) due to their antioxidative properties. In this study, the influence of 3-hydroxyflavone (H3) on the toxicity of ZnO NPs was investigated. H3 increased hydrodynamic size, polydispersity index and absolute value of the zeta potential of ZnO NPs, which indicated that H3 could influence the colloidal aspects of NPs. Surprisingly, H3 markedly decreased the initial concentration of ZnO NPs required to induce cytotoxicity to Caco-2, HepG2, THP-1 and human umbilical vein endothelial cells, which suggested that H3 could promote the toxicity of ZnO NPs to both cancerous and normal cells. For comparison, 6-hydroxyflavone did not show this effect. H3 remarkably increased cellular Zn elements and intracellular Zn ions in HepG2 cells following ZnO NP exposure, and co-exposure to H3 and NPs induced a relatively higher intracellular reactive oxygen species. Exposure to ZnO NPs at 3 hours induced the expression of endoplasmic reticulum stress markers DDIT3 and XBP-1 s, which was suppressed by H3. The expression of apoptotic genes BAX and CASP3 was significantly induced by ZnO NP exposure after 3 and 5 hours, respectively, and H3 further significantly promoted CASP3 expression at 5 hours. In combination, the results from this study suggested that H3 affected colloidal stability of ZnO NPs, promoted the interactions between NPs and cells, and altered the NP-induced endoplasmic reticulum stress-apoptosis signaling pathway, which finally enhanced the cytotoxicity of ZnO NPs.

Toxicity of ZnO nanoparticles (NPs) with or without hydrophobic surface coating to THP-1 macrophages: interactions with BSA or oleate-BSA

It is recently shown that biological macromolecules in food could interact with nanoparticles (NPs) and consequently change the biological effects of NPs. In this study, the interactions between ZnO NPs with or without hydrophobic surface coating and bovine serum albumin (BSA) or oleate (OA) complexed to BSA (OA-BSA) were assessed. Atomic force microscope (AFM) showed topographic changes of both types of NPs by BSA or OA-BSA, which could indicate the formation of protein corona. ZnO NPs showed negative Zeta potential, which was slightly decreased by BSA or OA-BSA, with OA-BSA being more effective. The UV-Vis was increased, whereas the fluorescence and synchronous fluorescence was decreased by the presence of ZnO NPs. Exposure to both types of ZnO NPs was associated with cytotoxicity to THP-1 macrophages, which was equally mitigated by BSA or OA-BSA associated with decreased cellular Zn elements. Exposure to ZnO NPs was associated with decreased release of cytokines, which was not affected by BSA or OA-BSA. In combination, the results from this study suggested that both BSA and OA-BSA could be adsorbed to ZnO NPs regardless of hydrophobic surface coating, which reduced the cytotoxicity of NPs to macrophages probably due to reduced association between NPs and cells. BSA and OA-BSA equally protected THP-1 macrophages from ZnO NP exposure, which might indicate that complexation to OA did not compromise the cytoprotective effects of BSA. These data might also indicate the complex interaction between NPs and biological macromolecules as food components, which should be considered for future nanotoxicological studies.

Cytotoxicity and ER stress-apoptosis gene expression in ZnO nanoparticle exposed THP-1 macrophages: influence of pre-incubation with BSA or palmitic acids complexed to BSA

In a biological microenvironment, biological macromolecules could interact with nanoparticles (NPs) and consequently influence the toxicity of NPs. This study investigated the effects of BSA or palmitic acids complexed to BSA (PA-BSA) on the toxicity of ZnO NPs to THP-1 macrophages. Atomic force microscopy showed the increase of NP heights after pre-incubation with BSA or PA-BSA, but PA-BSA more effectively altered the hydrodynamic size and zeta potential of NPs. Pre-incubation with BSA but not PA-BSA alleviated ZnO NP induced cytotoxicity, and transmission electron microscopy confirmed fewer intrastructural changes after exposure to ZnO NPs pre-incubated with BSA. ZnO NP exposure increased intracellular Zn ions but decreased reactive oxygen species (ROS) and release of soluble monocyte chemotactic protein-1 (sMCP-1), whereas pre-incubation with BSA and PA-BSA induced a different pattern of intracellular Zn ions and modestly increased intracellular ROS. The expression of ER stress marker DDIT3 was only significantly induced after exposure to NPs pre-incubated with PA-BSA, and CASP12 expression was significantly lower after exposure to NPs pre-incubated with BSA compared to NPs with or without pre-incubation of PA-BSA. In summary, these results showed that pre-incubation with BSA was more effective compared with PA-BSA to alleviate the toxicity of ZnO NPs to THP-1 macrophages, which should be considered for the evaluation of NP toxicity in a biological microenvironment.

Chemical Structures of Polyphenols That Critically Influence the Toxicity of ZnO Nanoparticles

Recent studies suggested that phytochemicals as natural antioxidants in food could alleviate nanoparticle (NP) toxicity. This study investigated the combined toxicity of ZnO NPs and a panel of polyphenols. Surprisingly, polyphenols with both high and almost no radical scavenging activities could elicit cytoprotective effects against NP exposure in Caco-2 cells, which were primarily influenced by the positions of the hydroxyl group. Polyphenols with different chemical structures variously influenced the hydrodynamic size, zeta potential, and solubility of ZnO NPs as well as NP-induced intracellular superoxide and Zn ions, which could all contribute to the combined effects. Responses of human endothelial cells appeared to be different from the responses of Caco-2 cells, which may indicate cell-type dependent responses to combined exposure of NPs and phytochemicals. In conclusion, the data from this study suggested a pivotal role of chemical structures of phytochemicals in determining their capacity to affect ZnO NP toxicity.

Toxicity of ZnO nanoparticles (NPs) to A549 cells and A549 epithelium in vitro: Interactions with dipalmitoyl phosphatidylcholine (DPPC)

Once inhaled, nanoparticles (NPs) will first interact with lung surfactant system, which may influence the colloidal aspects of NPs and consequently the toxic potential of NPs to pulmonary cells. In this study, we investigated the effects of dipalmitoyl phosphatidylcholine (DPPC), the major component in lung surfactant, on stability and toxicity of ZnO NPs. The presence of DPPC increased the UV-vis spectra, hydrodynamic size, Zeta potential and dissolution rate of ZnO NPs, which indicates that DPPC might interact with NPs and affect the colloidal stability of NPs. Exposure to ZnO NPs induced cytotoxicity associated with increased intracellular Zn ions but not superoxide in A549 cells. In A549 epithelium model, exposure to ZnO NPs induced cytotoxicity and decreased the release of interleukin 6 (IL-6) without a significant effect on epithelial permeability rate. Co-exposure of A549 cells or A549 epithelium model to DPPC and ZnO NPs induced a higher release of lactate dehydrogenase (LDH) and interleukin-6 (IL-6) compared with the exposure of ZnO NPs alone. We concluded that the presence of DPPC could influence the colloidal stability of ZnO NPs and increase the damage of NPs to membrane probably due to the increased positive surface charge.

The effects of baicalein or baicalin on the colloidal stability of ZnO nanoparticles (NPs) and toxicity of NPs to Caco-2 cells

Recent study suggested that the presence of phytochemicals in food could interact with nanoparticles (NPs) and consequently reduce the toxicity of NPs, which has been attributed to the antioxidant properties of phytochemicals. In this study, we investigated the interactions between ZnO NPs and two flavonoids baicalein (Ba) or baicalin (Bn) as well as the influence of the interactions on the toxicity of ZnO NPs to Caco-2 cells. The antioxidant properties of Ba and Bn were confirmed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays, with Ba being stronger. However, the presence of Ba or Bn did not significantly affect cytotoxicity, intracellular superoxide or release of inflammatory cytokines of Caco-2 cells after ZnO NP exposure. When Ba was present, the cellular viability of Caco-2 cells after exposure to ZnO NPs was slightly increased, associated with a modest decrease of intracellular Zn ions, but these effects were not statistically different. Ba was more effective than Bn at changing the hydrodynamic sizes, Zeta potential and UV-Vis spectra of ZnO NPs, which indicated that Ba might increase the colloidal stability of NPs. Taken together, the results of the present study indicated that the anti-oxidative phytochemical Ba might only modestly protected Caco-2 cells from the exposure to ZnO NPs associated with an insignificant reduction of the accumulation of intracellular Zn ions. These results also indicated that when assessing the combined effects of NPs and phytochemicals to cells lining gastrointestinal tract, it might be necessary to evaluate the changes of colloidal stability of NPs altered by phytochemicals.

The adverse vascular effects of multi-walled carbon nanotubes (MWCNTs) to human vein endothelial cells (HUVECs) in vitro: role of length of MWCNTs

Background

Increasing evidences indicate that exposure to multi-walled carbon nanotubes (MWCNTs) could induce adverse vascular effects, but the role of length of MWCNTs in determining the toxic effects is less studied. This study investigated the adverse effects of two well-characterized MWCNTs to human umbilical vein endothelial cells (HUVECs).

Methods

The internalization and localization of MWCNTs in HUVECs were examined by using transmission electron microscopy (TEM). The cytotoxicity of MWCNTs to HUVECs was assessed by water soluble tetrazolium-8 (WST-8), lactate dehydrogenase (LDH) and neutral red uptake assays. Oxidative stress was indicated by the measurement of intracellular glutathione (GSH) and reactive oxygen species (ROS). ELISA was used to determine the release of inflammatory cytokines. THP-1 monocyte adhesion to HUVECs was also measured. To indicate the activation of endoplasmic reticulum (ER) stress, the expression of ddit3 and xbp-1s was measured by RT-PCR, and BiP protein level was measured by Western blot.

Results

Transmission electron microscopy observation indicates the internalization of MWCNTs into HUVECs, with a localization in nuclei and mitochondria. The longer MWCNTs induced a higher level of cytotoxicity to HUVECs compared with the shorter ones. Neither of MWCNTs significantly promoted intracellular ROS, but the longer MWCNTs caused a higher depletion of GSH. Exposure to both types of MWCNTs significantly promoted THP-1 adhesion to HUVECs, accompanying with a significant increase of release of interleukin-6 (IL-6) but not tumor necrosis factor α (TNFα), soluble ICAM-1 (sICAM-1) or soluble VCAM-1 (sVCAM-1). Moreover, THP-1 adhesion and release of IL-6 and sVCAM-1 induced by the longer MWCNTs were significantly higher compared with the responses induced by the shorter ones. The biomarker of ER stress, ddit3 expression, but not xbp-1s expression or BiP protein level, was significantly induced by the exposure of longer MWCNTs.

Conclusions

Combined, these results indicated length dependent toxic effects of MWCNTs to HUVECs in vitro, which might be associated with oxidative stress and activation of ER stress.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0318-x) contains supplementary material, which is available to authorized users.

The presence of oleate stabilized ZnO nanoparticles (NPs) and reduced the toxicity of aged NPs to Caco-2 and HepG2 cells

The presence of food components may alter the colloidal aspects and toxicity of nanoparticles (NPs). In this study, the toxicity of ZnO NPs to Caco-2 and HepG2 cells was assessed, with the emphasis on the interactions between ZnO NPs and oleate (OA). The presence of OA increased UV-Vis spectra and hydrodynamic sizes, decreased Zeta potential, and markedly reduced the release of Zn ions from the dissolution of ZnO NPs, which combined indicated that OA could coat ZnO NPs and stabilize ZnO NPs. Exposure to ZnO NPs significantly induced cytotoxicity to Caco-2 and HepG2 cells, associated with increased intracellular Zn ions but not superoxide. When OA was added to the freshly prepared ZnO NP suspensions, the cytotoxicity, intracellular Zn ions and superoxide induced by ZnO NPs were not significantly affected. However, when ZnO NPs were aged for 24 h with the presence of OA, the cytotoxicity of ZnO NPs to Caco-2 and HepG2 cells was significantly reduced, associated with a reduction of intracellular Zn ions. The results from this study suggested that the presence of OA could increase colloidal stability of ZnO NPs and consequently reduce the toxicity of ZnO NPs after aging associated with reduced accumulation of intracellular Zn ions.