Cell cycle dependent cellular uptake of zinc oxide nanoparticles in human epidermal cells

Cytotoxicity of green synthesized zinc oxide nanoparticles using Musa acuminata on Vero cells

Zinc oxide nanoparticles (ZnO NPs) have become a highly regarded substance in various industries especially biologically synthesized ZnO NPs due to their adherence to the principles of green chemistry. However, concerns have been raised regarding the potential cytotoxic effects of ZnO NPs on biological systems. This study aimed to investigate and compare the cytotoxicity of ZnO NPs that were synthesized through chemical (C-ZnO NPs) and green approach using Musa acuminata leaf aqueous extract (Ma-ZnO NPs) on Vero cells. Characterization of ZnO NPs through Uv-Vis, FESEM, EDX, XRD, FTIR and XPS confirmed the successful synthesis of C- and Ma-ZnO NPs. MTT and ROS assays revealed that C- and Ma-ZnO NPs induced a concentration- and time-dependent cytotoxic effect on Vero cells. Remarkably, Ma-ZnO NPs showed significantly higher cell viability compared to C-ZnO NPs. The corelation of ROS and vell viability suggest that elevated ROS levels can lead to cell damage and even cell death. Flow cytometry analysis indicated that Ma-ZnO NPs exposed cells had more viable cells and a smaller cell population in the late and early apoptotic stage. Furthermore, more cells were arrested in the G1 phase upon exposure to C-ZnO NPs, which is associated with oxidative stress and DNA damage caused by ROS generation, proving its higher cytotoxicity than Ma-ZnO NPs. Similarly, time-dependent cytotoxicity and morphological alterations were observed in C- and Ma-ZnO NPs treated cells, indicating cellular damage. Furthermore, fluorescence microscopy also demonstrated a time-dependent increase in ROS formation in cells exposed to C- and Ma-ZnO NPs. In conclusion, the findings suggest that green ZnO NPs possess a favourable biocompatibility profile, exhibiting reduced cytotoxicity compared to chemically synthesized ZnO NPs on Vero cells. These results emphasize the potential of green synthesis methods for the development of safer and environmentally friendly ZnO NPs.

Gene expression profiles and protein-protein interaction networks in THP-1 cells exposed to metal-based nanomaterials

We analyzed gene expression in THP-1 cells exposed to metal-based nanomaterials (NMs) [TiO2 (NM-100), ZnO (NM-110), SiO2 (NM-200), Ag (NM-300 K)]. A functional enrichment analysis of the significant differentially expressed genes (DEGs) identified the key modulated biological processes and pathways. DEGs were used to construct protein-protein interaction networks. NM-110 and NM-300 K induced changes in the expression of genes involved in oxidative and genotoxic stress, immune response, alterations of cell cycle, detoxification of metal ions and regulation of redox-sensitive pathways. Both NMs shared a number of highly connected protein nodes (hubs) including CXCL8, ATF3, HMOX1, and IL1B. NM-200 induced limited transcriptional changes, mostly related to the immune response; however, several hubs (CXCL8, ATF3) were identical with NM-110 and NM-300 K. No effects of NM-100 were observed. Overall, soluble nanomaterials NM-110 and NM-300 K exerted a wide variety of toxic effects, while insoluble NM-200 induced immunotoxicity; NM-100 caused no detectable changes on the gene expression level.

A surge of copper accumulation in cell division revealed its cyclical kinetics in synchronized green alga Chlamydomonas reinhardtii

Trace transition metal uptake is tightly associated with cellular biological processes. Herein, we demonstrated that copper (Cu) bioaccumulation and uptake were controlled by the cell cycle. A cyclical kinetics of Cu bioaccumulation and surge in S/M phase were observed in the synchronized green algae Chlamydomonas reinhardtii. The labile Cu(I) content also increased in the S/M phase, although the increase was moderate. Based on the comparative analysis of bioaccumulation and transcriptome data, we found the CRR1-mediated Cu uptake pathway, and CTR1 and CTR2 transporters were regulated by the intracellular Cu quota and suppressed during cell division with high Cu content. In contrast, we hypothesized a novel intracellular Cu-quota-independent Cu(I) uptake pathway in which the transporter COPT1 might be responsible for the Cu influx during cell division. Besides, a plunge of ATX1 expression level was also observed during cell division, which indicated an inhibition of the secretory pathway of Cu with the participation of ATX1 in terms of transcriptome level, probably resulting in reduced Cu efflux. Additionally, both fluorometric probe staining and transcriptomic data demonstrated that mitochondria were the dominant destination for the extra Cu content in S/M phase. Finally, some cytotoxic responses were also observed in S/M phase. Pathways related to reactive oxygen species and glutamine metabolic process were enriched in GO term and KEGG enrichment analysis, and glutathione content and cell membrane permeability determined by fluorometric probes also increased during cell division. This study showed a sharp increase of Cu uptake in cell division and revealed the genetic regulation mechanisms for the cell cycle control of Cu uptake.

Mechanistic study of copper oxide, zinc oxide, cadmium oxide, and silver nanoparticles-mediated toxicity on the probiotic Lactobacillus reuteri

The use of metal/metal oxide nanoparticles (NPs) in consumer products has increased dramatically. Accordingly, human exposure to these NPs has increased. Lactobacillus reuteri, a member of the beneficial gut microbiota, is essential for human health. In the present study, the toxic effect of three metal oxides (CuO, ZnO, and CdO) and one metal (Ag) NPs on L. reuteri were investigated in vitro. L. reuteri was susceptible to all the prepared NPs in a dose-dependent manner, visualized as an increase in the zones of inhibition and a significant reduction in the maximum specific growth rates (µmax). The minimal inhibitory concentrations were 5.8, 26, 560, and 560 µg/mL for CdO-, Ag-, ZnO-, and CuO-NPs, respectively, and the respective minimal bactericidal concentrations were 60, 70, 1500, and 1500 µg/mL. Electron microscopic examinations revealed the adsorption of the prepared NPs on L. reuteri cell surface, causing cell wall disruption and morphological changes. These changes were accompanied by significant leakage of cellular protein content by 214%, 191%, 112%, and 101% versus the untreated control when L. reuteri was treated with CdO-, Ag-, CuO-, and ZnO-NPs, respectively. NPs also induced oxidative damage, where the malondialdehyde level was significantly increased, and glutathione content was significantly decreased. Quantifying the DNA damage using comet assay showed that CuONPs had the maximum DNA tail length (8.2 px vs. 2.1 px for the control). While CdONPs showed the maximum percentage of DNA in tail (15.5% vs. 3.1%). This study provides a mechanistic evaluation of the NPs-mediated toxicity to a beneficial microorganism.

Effects of Zinc Oxide Nanoparticle Exposure on Human Glial Cells and Zebrafish Embryos

Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ions in the in vitro and in vivo observed effects, we measured their release from ZnO NPs with flame atomic absorption spectrometry. Then, cells and zebrafish embryos were treated with a water-soluble salt (zinc sulfate) at concentrations that equal the number of Zn2+ ions released by the tested concentrations of ZnO NPs. Exposure to ZnO NPs induced morphological alterations and a significant decrease in cell viability depending on the concentration and duration of treatment, even after removing the overestimation due to NP interference. Although there were no signs of acute toxicity in zebrafish embryos, a decrease in hatching was detected after exposure to the highest ZnO NP concentrations tested. The ability of ZnO NPs to release Zn2+ ions into the medium in a concentration-dependent manner was confirmed. Zn2+ ions did not seem entirely responsible for the effects observed in the glial cells, but they were likely responsible for the decrease in zebrafish hatching rate. The results obtained in this work contribute to the knowledge of the toxicological potential of ZnO NPs.

Bee venom (Apis mellifera L.) rescues zinc oxide nanoparticles induced neurobehavioral and neurotoxic impact via controlling neurofilament and GAP-43 in rat brain

This study investigated the possible beneficial role of the bee venom (BV, Apis mellifera L.) against zinc oxide nanoparticles (ZNPs)-induced neurobehavioral and neurotoxic impacts in rats. Fifty male Sprague Dawley rats were alienated into five groups. Three groups were intraperitoneally injected distilled water (C 28D group), ZNPs (100 mg/kg b.wt) (ZNPs group), or ZNPs (100 mg/kg.wt) and BV (1 mg/ kg.bwt) (ZNPs + BV group) for 28 days. One group was intraperitoneally injected with 1 mL of distilled water for 56 days (C 56D group). The last group was intraperitoneally injected with ZNPs for 28 days, then BV for another 28 days at the same earlier doses and duration (ZNPs/BV group). Depression, anxiety, locomotor activity, spatial learning, and memory were evaluated using the forced swimming test, elevated plus maze, open field test, and Morris water maze test, respectively. The brain contents of dopamine, serotonin, total antioxidant capacity (TAC), malondialdehyde (MDA), and Zn were estimated. The histopathological changes and immunoexpressions of neurofilament and GAP-43 protein in the brain tissues were followed. The results displayed that BV significantly decreased the ZNPs-induced depression, anxiety, memory impairment, and spatial learning disorders. Moreover, the ZNPs-induced increment in serotonin and dopamine levels and Zn content was significantly suppressed by BV. Besides, BV significantly restored the depleted TAC but minimized the augmented MDA brain content associated with ZNPs exposure. Likewise, the neurodegenerative changes induced by ZNPs were significantly abolished by BV. Also, the increased neurofilament and GAP-43 immunoexpression due to ZNPs exposure were alleviated with BV. Of note, BV achieved better results in the ZNPs + BV group than in the ZNPs/BV group. Conclusively, these results demonstrated that BV could be employed as a biologically effective therapy to mitigate the neurotoxic and neurobehavioral effects of ZNPs, particularly when used during ZNPs exposure.

Antibacterial Activity of Nanostructured Zinc Oxide Tetrapods

Zinc oxide (ZnO) tetrapods as microparticles with nanostructured surfaces show peculiar physical properties and anti-infective activities. The aim of this study was to investigate the antibacterial and bactericidal properties of ZnO tetrapods in comparison to spherical, unstructured ZnO particles. Additionally, killing rates of either methylene blue-treated or untreated tetrapods and spherical ZnO particles for Gram-negative and Gram-positive bacteria species were determined. ZnO tetrapods showed considerable bactericidal activity against Staphylococcus aureus, and Klebsiella pneumoniae isolates, including multi-resistant strains, while Pseudomonas aeruginosa and Enterococcus faecalis remained unaffected. Almost complete elimination was reached after 24 h for Staphylococcus aureus at 0.5 mg/mL and Klebsiella pneumoniae at 0.25 mg/mL. Surface modifications of spherical ZnO particles by treatment with methylene blue even improved the antibacterial activity against Staphylococcus aureus. Nanostructured surfaces of ZnO particles provide active and modifiable interfaces for the contact with and killing of bacteria. The application of solid state chemistry, i.e., the direct matter-to-matter interaction between active agent and bacterium, in the form of ZnO tetrapods and non-soluble ZnO particles, can add an additional principle to the spectrum of antibacterial mechanisms, which is, in contrast to soluble antibiotics, depending on the direct local contact with the microorganisms on tissue or material surfaces.

Husk-like Zinc Oxide Nanoparticles Induce Apoptosis through ROS Generation in Epidermoid Carcinoma Cells: Effect of Incubation Period on Sol-Gel Synthesis and Anti-Cancerous Properties

This study effectively reports the influence of experimental incubation period on the sol-gel production of husk-like zinc oxide nanoparticles (ZNPs) and their anti-cancerous abilities. The surface morphology of ZNPs was studied with the help of SEM. With the use of TEM, the diameter range of the ZNPs was estimated to be ~86 and ~231 nm for ZNP^A and ZNP^B, prepared by incubating zinc oxide for 2 and 10 weeks, respectively. The X-ray diffraction (XRD) investigation showed that ZNPs had a pure wurtzite crystal structure. On prolonging the experimental incubation, a relative drop in aspect ratio was observed, displaying a distinct blue-shift in the UV-visible spectrum. Furthermore, RBC lysis assay results concluded that ZNP^A and ZNP^B both demonstrated innoxious nature. As indicated by MTT assay, reactive oxygen species (ROS) release, and chromatin condensation investigations against the human epidermoid carcinoma (HEC) A431 cells, ZNP^B demonstrated viable relevance to chemotherapy. Compared to ZNP^B, ZNP^A had a slightly lower IC₅₀ against A431 cells due to its small size. This study conclusively describes a simple, affordable method to produce ZNP nano-formulations that display significant cytotoxicity against the skin cancer cell line A431, suggesting that ZNPs may be useful in the treatment of cancer.

Mechanistic Approaches to the Application of Nano-Zinc in the Poultry and Biomedical Industries: A Comprehensive Review of Future Perspectives and Challenges

Bio-fortification is a new, viable, cost-effective, and long-term method of administering crucial minerals to a populace with limited exposure to diversified foods and other nutritional regimens. Nanotechnology entities aid in the improvement of traditional nutraceutical absorption, digestibility, and bio-availability. Nano-applications are employed in poultry systems utilizing readily accessible instruments and processes that have no negative impact on animal health and welfare. Nanotechnology is a sophisticated innovation in the realm of biomedical engineering that is used to diagnose and cure various poultry ailments. In the 21st century, zinc nanoparticles had received a lot of considerable interest due to their unusual features. ZnO NPs exhibit antibacterial properties; however, the qualities of nanoparticles (NPs) vary with their size and structure, rendering them adaptable to diverse uses. ZnO NPs have shown remarkable promise in bio-imaging and drug delivery due to their high bio-compatibility. The green synthesized nanoparticles have robust biological activities and are used in a variety of biological applications across industries. The current review also discusses the formulation and recent advancements of zinc oxide nanoparticles from plant sources (such as leaves, stems, bark, roots, rhizomes, fruits, flowers, and seeds) and their anti-cancerous activities, activities in wound healing, and drug delivery, followed by a detailed discussion of their mechanisms of action.

MiR-206 conjugated gold nanoparticle based targeted therapy in breast cancer cells

MicroRNAs (miRNAs) are single-stranded, non-coding, 19–25 nucleotide RNA molecules that have been observed to be dysregulated in many diseases including cancer. miRNAs have been known to play an important role in cellular proliferation, differentiation, migration, apoptosis, survival, and morphogenesis. Breast cancer is heterogeneous in nature and contributed extensively to the increased mortality rate. miRNA can either be tumor-suppressive or oncogenic in nature. The level of expression of miRNA changes according to the subtypes of cancer and the mutation responsible for different cancers. miRNA mimicry or inhibition are emerging possible therapies to maintain the level of miRNA inside the cells. In order to have proper miRNA mimicry, the major hurdle is to deliver the miRNA mimics at the site of tumor. Metallic nanoparticles with modified surface can be used to solve the problem of miRNA delivery. MiR-206 is reported to be down-regulated in Luminal-A type of breast cancer. In the current manuscript, we aim to modify the surface of gold-nanoparticles (AuNPs) with PEG moiety and allow miRNA to attach to it. The fabricated nano-complex, not only delivered miR-206 but also caused cell death in MCF-7 by arresting cells in the G0-G1 phase and inducing apoptosis by downregulating NOTCH 3.

Effects of Golden Thistle (Scolymus hispanicus L.) on Cytotoxic Activity: Cell Cycle Arrest and Apoptotic Properties on the CaCo-2 Cell Line

Cancer is a global concern for many individuals with high mortality rates, with colon cancer being the third most common diagnosed cancer worldwide. A phytochemical-rich diet is often recommended in the prevention and during the treatment of cancer cases. Golden thistle (GT) plant (Scolymus hispanicus L.) is a wild edible plant widely consumed in the Mediterranean countries. In this study, we aimed to obtain a hydromethanolic extract from three parts of the GT plant and test its antiproliferative activity in the CaCo-2 human adenocarcinoma cell line. Concentrations of the golden thistle extract (GTE) were used to treat CaCo-2 cells and the most significant reduction was detected with 4 mg/mL GTE after 72 h, with 78.3% decrease in cell viability (P < .05). Additionally, 4 mg/mL GTE caused 7.8-fold higher release of lactate dehydrogenase enzyme, indicating cell death after treatment. Flow cytometric analyses concluded both 3.3-fold higher early and late apoptotic activity of the 4 mg/mL GTE compared with the nontreated control group (P < .05). Last, 4 mg/mL GTE showed 24.1% reduction in the G1 phase and 38.1% increase in the S phase of cell cycle distribution. The alteration of G1 and S phases in the cell cycle led to growth reduction of CaCo-2 cells and caused apoptosis.

L-Cysteine capped zinc oxide nanoparticles induced cellular response on adenocarcinomic human alveolar basal epithelial cells using a conventional and organ-on-a-chip approach

Zinc oxide nanoparticles (ZnO NPs) are among the well-characterized nanomaterials with multifaceted biomedical applications, including biomedical imaging, drug delivery, and pharmaceutical preparations. The high surface charge of ZnO NPs leads to the agglomeration of the particles. Therefore, surface coating with a suitable ligand can increase colloidal stability. In this present study, in-vitro responses of ZnO NPs capped with a sulfur-containing amino acid, L-cysteine (Cys-ZnO NPs), on A549 cells was investigated. Fourier Transform Infrared Spectroscopy (FTIR) studies were carried out to confirm the capping of ZnO NPs with L-cysteine. Cytotoxic studies using A549 cells demonstrated reduced cytotoxicity in comparison with already reported pristine Zinc Oxide nanoparticles. The cellular uptake is confirmed by fluorescent cytometry. However, a higher concentration (160 µg/mL) of Cys-ZnO NPs led to apoptotic cell death marked by nuclear condensation, mitochondrial membrane depolarization, actin filament condensation, lysosomal damage LDH leakage, intracellular ROS production, blebbing, upregulation of Bax and downregulation of Bcl-2 gene expression. Cys-ZnO NPs treatment was also carried out in cells cultured in a microfluidic lung-on-a-chip device under a physiologically relevant flow rate. The study concluded that the microfluidic-based lung-on-a-chip culture resulted in reduced cell death compared to the conventional condition.

Histological and biochemical apoptosis changes of female rats' ovary by Zinc oxide nanoparticles and potential protective effects of l-arginine: An experimental study

Background

This research aims to investigate the adverse effects of ZnO NP on ovarian tissue and the follicular and menstrual cycle and the protective effects of l-arginine on the aforementioned tissues.

Material and methods

30 rats were divided into five groups. The first group was the control group. The second and fourth groups received 100 mg/kg and 200 mg/kg ZnO NP, respectively. The third and fifth groups received the same doses of ZnO NP as the second and fourth groups, respectively. However, the third and fifth groups received an additional dose of 1.3 gr/kg of LA amino acid. ZnO NP and LA are given intraperitoneal for 21 days. Blood samples from each rat and a part of the ovarium were collected to test for gene expression and histological analysis.

Results

Compared to levels of housekeeping gene β-actine, levels of apoptosis effectors such as Bax, Bcl, Caspase 3, and Caspase 9 were significantly increased in all groups. In groups that received doses of LA (three and five), atretic follicle size was smaller compared to groups that did not receive LA (two and four). In addition, in the third group, the secondary and primordial follicle's generated oocytes were smaller compared with groups two, four, and five. Compared with the control group, all groups experienced morphological degeneration of follicles and tissue.

Conclusion

ZnO NP has inevitable, morphological, and physiological effects on the ovary and can detrimentally impact the tissue. LA can aid in the regeneration of the tissue and block damage induced by stress and toxicity.

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Zinc oxide nanoparticles are widely used in various everyday products, such as food packaging, additives, cosmetics, and bioimaging.

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Using Zinc oxide nanoparticles in daily life may cause infertility by reducing the number of follicles in the ovary.

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L-Arginine may be a beneficial daily supplement to prevent damage to the ovaries induced by Zinc oxide nanoparticles.

A Focus on "Bio" in Bio-Nanoscience: The Impact of Biological Factors on Nanomaterial Interactions

Bio-nanoscience research encompasses studies on the interactions of nanomaterials with biological structures or what is commonly referred to as the biointerface. Fundamental studies on the influence of nanomaterial properties, including size, shape, composition, and charge, on the interaction with the biointerface have been central in bio-nanoscience to assess nanomaterial efficacy and safety for a range of biomedical applications. However, the state of the cells, tissues, or biological models can also influence the behavior of nanomaterials at the biointerface and their intracellular processing. Focusing on the "bio" in bio-nano, this review discusses the impact of biological properties at the cellular, tissue, and whole organism level that influences nanomaterial behavior, including cell type, cell cycle, tumor physiology, and disease states. Understanding how the biological factors can be addressed or exploited to enhance nanomaterial accumulation and uptake can guide the design of better and suitable models to improve the outcomes of materials in nanomedicine.

Application of nanoparticles in cancer therapy with an emphasis on cell cycle

Owing to their unique characteristics, nanoparticles (NPs) could be incorporated into valuable therapeutic modalities for different diseases; however, there are many concerns about risk factors in human applications. NPs carry therapeutic chemicals that could improve the outcome of cancer therapies. Nowadays, NPs are being recognized as important and strategic agents in treatment of several disorders due to their unique properties in targeting malignant cells in tumor sites. Numerous investigations have shown that the majority of chemotherapeutic agents can be modified through entrapment in submicron colloidal systems. Still, there are problems and limitations in application of NPs in cancer therapy. The aim of the present study is to focus on potential NPs usage in cancer treatment with an emphasis on the cell cycle of malignant cells.

Fabrication of methotrexate-loaded gold nanoconjugates and its enhanced anticancer activity in breast cancer

Methotrexate (MTX) is known antagonist of folic acid and widely used as an anti-cancer drug. The folate receptor (FR) and reduced folate carrier are mostly responsible for internalization of methotrexate in tumor cells. Mutation in reduced folate carrier (RFC) leads to resistance against MTX in various tumor cell lines including MDA-MB-231 breast cancer cells. To overcome the resistance of MTX, folate receptor targeted nanoparticles have been commonly used for targeting breast tumors. The aim of the study is to determine the ability of methotrexate gold nanoparticles (MTX-GNPs) in the induction of apoptosis and to explore the molecular changes at genomics and proteomics level. Different assays like cell viability assay, cell cycle analysis, apoptosis, real-time PCR and western blot were carried out to evaluate the anti-cancer effect of MTX-Gold NPs on MCF-7 and MDA-MB-231 cells. Our observations demonstrated the decrease in the percent viable cells after the treatment of MTX-GNPs, with an arrest in cell cycle at G0/G1 phase and a significant increase in apoptotic cell population and loss of mitochondrial membrane potential in MCF-7 and MDA-MB-231 cells. Folate receptor targeted MTX-GNPs showed significant cellular uptake in breast cancer cells along with significant down-regulation in expression of anti-apoptotic gene (Bcl-2) and up-regulation in expression of pro-apoptotic genes (Bax, Caspase-3, Caspase-9, APAF-1, p53). These results unveil the increased anti-cancer effect of MTX-GNPs in cancer cells.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02718-7.

Investigating the Internalization and COVID-19 Antiviral Computational Analysis of Optimized Nanoscale Zinc Oxide

Global trials are grappling toward identifying prosperous remediation against the ever-emerging and re-emerging pathogenic respiratory viruses. Battling coronavirus, as a model respiratory virus, via repurposing existing therapeutic agents could be a welcome move. Motivated by its well-demonstrated curative use in herpes simplex and influenza viruses, utilization of the nanoscale zinc oxide (ZnO) would be an auspicious approach. In this direction, ZnO nanoparticles (NPs) were fabricated herein and relevant aspects related to the formulation such as optimization, structure, purity, and morphology were elucidated. In silico molecular docking was conducted to speculate the possible interaction between ZnO NPs and COVID-19 targets including the ACE2 receptor, COVID-19 RNA-dependent RNA polymerase, and main protease. The cellular internalization of ZnO NPs using human lung fibroblast cells was also assessed. Optimized hexagonal and spherical ZnO nanostructures of a crystallite size of 11.50 ± 0.71 nm and positive charge were attained. The pure and characteristic hexagonal wurtzite P63mc crystal structure was also observed. Interestingly, felicitous binding of ZnO NPs with the three tested COVID-19 targets, via hydrogen bond formation, was detected. Furthermore, an enhanced dose-dependent cellular uptake was demonstrated. The obtained results infer a rationale, awaiting validation from further biological and therapeutic studies.

A review: non-antibacterial, non-antifungal and non-anticancer properties of nanoparticles the forgotten paradigm

The review highlights the need of non-antibacterial, non-antifungal and non-anticancer characters of metal or metal oxide nanoparticles. The usage of nanoparticles as a part of therapeutic measures results in certain unfavourable effects. The nanoparticles can disturb healthy gut microorganisms that may bring about some health damages regarding pathogenic diseases, obesity, and inflammation likewise. Even the nonspecific interactions of nanoparticles with healthy cells and tissues can cause altered expressions of various pro-inflammatory factors and stress related genes. This review indicates and prospect about the demand of nanoparticles with non-antibacterial, non-antifungal and non-anticancer properties. Such nanoparticles will be effective in various remedial and diagnostic purposes.

Zinc oxide nanoparticles synthesized from Aspergillus terreus induces oxidative stress-mediated apoptosis through modulating apoptotic proteins in human cervical cancer HeLa cells

OBJECTIVES

This study was aimed to analyze the cytotoxicity of biogenic zinc oxide nanoparticles (ZnO NPs) in human cervical epithelial cancer HeLa.

METHODS

The ZnO NPs was synthesized from the culture filtrated of Aspergillus terreus, and examined by UV-spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray (EDX) and Fourier transform infrared (FTIR) analysis. The cytotoxicity of synthesized ZnO NPs was analyzed by the MTT assay, and the expression of apoptotic proteins was examined by Western blot analyses.

KEY FINDINGS

The ZnO NPs exhibited concentration-dependent cytotoxicity on HeLa cells and induced the apoptosis as evidenced by reduced superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) levels, and increased reactive oxygen species (ROS) and diminished mitochondrial membrane potential (MMP) was noticed in ZnO NPs treated HeLa cells. Western blot analyses explored that the Bcl-2 expression was significantly downregulated, whereas, the expression of p53, Bax, Caspase-3, Caspase-9 and Cytochrome-c were significantly upregulated in ZnO NPs treated cells.

CONCLUSION

Consequently, the mycosynthesized ZnO NPs induces apoptosis in HeLa cells by persuading oxidative damage and modulating the apoptotic proteins. Therefore, A. terreus synthesized ZnO NPs could be used as an effective chemotherapeutic agent for cervical cancer treatment.

Enhanced Internalization of Nanoparticles Following Ionizing Radiation Leads to Mitotic Catastrophe in MG-63 Human Osteosarcoma Cells

This study aims to investigate whether ionizing radiation combined with doxorubicin-conjugated iron oxide nanoparticles (NP-DOX) improves the internalization and cytotoxic effects of the nano-carrier-mediated drug delivery in MG-63 human osteosarcoma cells. NP-DOX was designed and synthesized using the co-precipitation method. Highly stable and crystalline nanoparticles conjugated with DOX were internalized in MG-63 cells through macropinocytosis and located in the perinuclear area. Higher nanoparticles internalization in MG-63 cells previously exposed to 1 Gy X-rays was correlated with an early accumulation of cells in G₂/M, starting at 12 h after treatment. After 48 h, the application of the combined treatment led to higher cytotoxic effects compared to the individual treatment, with a reduction in the metabolic capacity and unrepaired DNA breaks, whilst a low percent of arrested cells, contributing to the commitment of mitotic catastrophe. NP-DOX showed hemocompatibility and no systemic cytotoxicity, nor histopathological alteration of the main organs.

Recent aspects of the effects of zinc on human health

Zinc (Zn) is one of the most important essential nutrients of great public health significance. It is involved in numerous biological functions and it is considered as a multipurpose trace element, due to its capacity to bind to more than 300 enzymes and more than 2000 transcriptional factors. Its role in biochemical pathways and cellular functions, such as the response to oxidative stress, homeostasis, immune responses, DNA replication, DNA damage repair, cell cycle progression, apoptosis and aging is significant. Zn is required for the synthesis of protein and collagen, thus contributing to wound healing and a healthy skin. Metallothioneins are metal-binding proteins and they are potent scavengers of heavy metals, including Zn, and protect the organism against stress. Zn deficiency is observed almost in 17% of the global population and affects many organ systems, leading to dysfunction of both humoral and cell-mediated immunity, thus increasing the susceptibility to infection. This review gives a thorough insight into the most recent evidence on the association between Zn biochemistry and human pathologies, epigenetic processes, gut microbial composition, drug targets and nanomedicine.

Toxicity of binary mixtures of Al2O3 and ZnO nanoparticles toward fibroblast and bronchial epithelium cells

The objective of this study was to examine the cytotoxic effects of binary mixtures of Al₂O₃ and ZnO NPs using mouse fibroblast cells (L929) and human bronchial epithelial cells (BEAS-2B) as biological test systems. The synergistic, additive, or antagonistic behavior of the binary mixture was also investigated. In toxicity experiments, cellular morphology, mitochondrial function (MTT assay), apoptosis, nuclear size and shape, clonogenic assays, and damage based upon oxidative stress parameters were assessed under control and NPs exposure conditions. Although Abbott modeling results provided no clear evidence of the binary mixture of Al₂O₃ and ZnO NPs exhibiting synergistic toxicity, some specific assays such as apoptosis, nuclear size and shape, clonogenic assay, activities of antioxidant enzymatic enzymes catalase, superoxide dismutase, and levels of glutathione resulted in enhanced toxicity for the mixtures with 1 and 1.75 toxic units (TU) toward both cell types. Data demonstrated that co-presence of Al₂O₃ and ZnO NPs in the same environment might lead to more realistic environmental conditions. Our findings indicate cytotoxicity of binary mixtures of Al₂O₃ and ZnO NPs produced greater effects compared to toxicity of either individual compound.

Understanding cellular interactions with nanomaterials: towards a rational design of medical nanodevices

Biomedical applications increasingly require fully characterized new nanomaterials. There is strong evidence showing that nanomaterials not only interact with cells passively but also actively, mediating essential molecular processes for the regulation of cellular functions, but we are only starting to understand the mechanisms of those interactions. Systematic studies about cell behavior as a response to specific nanoparticle properties are scarce in the literature even when they are necessary for the rational design of medical nanodevices. Information in the literature shows that the physicochemical properties determine the bioactivity, biocompatibility, and safety of nanomaterials. The information available regarding the interaction and responses of cells to nanomaterials has not been analyzed and discussed in a single document. Hence, in this review, we present the latest advances about cellular responses to nanomaterials and integrate the available information into concrete considerations for the development of innovative, efficient, specific and, more importantly, safe biomedical nanodevices. We focus on how physicochemical nanoparticle properties (size, chemical surface, shape, charge, and topography) influence cell behavior in a first attempt to provide a practical guide for designing medical nanodevices, avoiding common experimental omissions that may lead to data misinterpretation. Finally, we emphasize the importance of the systematic study of nano-bio interactions to acquire sufficient reproducible information that allows accurate control of cell behavior based on tuning of nanomaterial properties. This information is useful to guide the design of specific nanodevices and nanomaterials to elicit desired cell responses, like targeting, drug delivery, cell attachment, differentiation, etc, or to avoid undesired side effects.

Differential Cytotoxicity Induced by Transition Metal Oxide Nanoparticles is a Function of Cell Killing and Suppression of Cell Proliferation

The application of nanoparticles (NPs) in industry is on the rise, along with the potential for human exposure. While the toxicity of microscale equivalents has been studied, nanoscale materials exhibit different properties and bodily uptake, which limits the prediction ability of microscale models. Here, we examine the cytotoxicity of seven transition metal oxide NPs in the fourth period of the periodic table of the chemical elements. We hypothesized that NP-mediated cytotoxicity is a function of cell killing and suppression of cell proliferation. To test our hypothesis, transition metal oxide NPs were tested in a human lung cancer cell model (A549). Cells were exposed to a series of concentrations of TiO₂, Cr₂O₃, Mn₂O₃, Fe₂O₃, NiO, CuO, or ZnO for either 24 or 48 h. All NPs aside from Cr₂O₃ and Fe₂O₃ showed a time- and dose-dependent decrease in viability. All NPs significantly inhibited cellular proliferation. The trend of cytotoxicity was in parallel with that of proliferative inhibition. Toxicity was ranked according to severity of cellular responses, revealing a strong correlation between viability, proliferation, and apoptosis. Cell cycle alteration was observed in the most toxic NPs, which may have contributed to promoting apoptosis and suppressing cell division rate. Collectively, our data support the hypothesis that cell killing and cell proliferative inhibition are essential independent variables in NP-mediated cytotoxicity.

Advances and controversies in studying sunscreen delivery and toxicity

This review critically evaluates the sunscreen delivery and toxicity field. We chose to focus on approved sunscreens in this review. Optimal sunscreen use prevents skin cancer and photoageing but there is an important knowledge gap in sunscreen/skin interactions. Sunscreen delivery is a key for efficacy, but studying sunscreen delivery is not straightforward. We review the strengths and weaknesses of in vitro, excised skin and clinical approaches. Understanding positive and negative sunscreen effects on skin homeostasis is also challenging. The results in this field, especially in vitro testing, are controversial and experimental design varies widely which further supports disparities between some findings. We hypothesize that bias towards showing sunscreen toxicity to increase impact could be problematic. We explore that perception through a detailed review of experimental design, especially in cell culture models. Our conclusion is that emerging, non- and minimally invasive technologies are enabling new approaches to volunteer studies that could significantly improve knowledge of sunscreen delivery and interactions.

Heterogeneity in Biodistribution and Cytotoxicity of Silver Nanoparticles in Pulmonary Adenocarcinoma Human Cells

Cellular association of nanoparticles (NPs) and their resultant cytotoxicity are heterogeneous in nature and can be influenced by the variances in NPs' properties, cell types, and status. However, conventional in vitro assays typically consider the administered NP dose and the averaged cellular responses based on the assumption of a uniform distribution of monodisperse NPs in homogeneous cells, which might be insufficient to describe the complex nature of cell-NP interactions. Here, using flow cytometry, we report observations of the heterogeneity in the cellular association of silver nanoparticles (AgNPs) in A549 cells, which resulted in distinct dose-response relationships and cytotoxicity. Type I and Type II cells were moderately associated with AgNPs but as the cellular AgNP dose increased, Type I cells remained viable while Type II cells became less viable. Type III cells did not have high affinity with AgNPs but were, however, the least viable. Transmission electron microscopic images revealed that the biodistribution and the released Ag+ ions contributed to the distinct toxic effects of AgNPs in different populations. This single-cell dose-response analysis approach enabled the examination of how differently individual cells responded to different cellular NP doses and provided insights into nanotoxicity pathways at a single-cell level.

In Vitro Toxicity of TiO2:SiO2 Nanocomposites with Different Photocatalytic Properties

The enormous technological relevance of titanium dioxide (TiO2) nanoparticles (NPs) and the consequent concerns regarding potentially hazardous effects that exposure during production, use, and disposal can generate, encourage material scientists to develop and validate intrinsically safe design solution (safe-by-design). Under this perspective, the encapsulation in a silica dioxide (SiO2) matrix could be an effective strategy to improve TiO2 NPs safety, preserving photocatalytic and antibacterial properties. In this work, A549 cells were used to investigate the toxic effects of silica-encapsulated TiO2 having different ratios of TiO2 and SiO2 (1:1, 1:3, and 3:1). NPs were characterized by electron microscopy and dynamic light scattering, and cell viability, oxidative stress, morphological changes, and cell cycle alteration were evaluated. Resulting data demonstrated that NPs with lower content of SiO2 are able to induce cytotoxic effects, triggered by oxidative stress and resulting in cell necrosis and cell cycle alteration. The physicochemical properties of NPs are responsible for their toxicity. Particles with small size and high stability interact with pulmonary cells more effectively, and the different ratio among silica and titania plays a crucial role in the induced cytotoxicity. These results strengthen the need to take into account a safe(r)-by-design approach in the development of new nanomaterials for research and manufacturing.

Microbial synthesis of zinc oxide nanoparticles and their potential application as an antimicrobial agent and a feed supplement in animal industry: a review

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles (NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods. Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, non-toxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal's body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals.

Effects of carbon dots surface functionalities on cellular behaviors - Mechanistic exploration for opportunities in manipulating uptake and translocation

Carbon dots (CDots) for their excellent optical and other properties have been widely pursued for potential biomedical applications, in which a more comprehensive understanding on the cellular behaviors and mechanisms of CDots is required. For such a purpose, two kinds of CDots with surface passivation by 3-ethoxypropylamine (EPA-CDots) and oligomeric polyethylenimine (PEI-CDots) were selected for evaluations on their uptakes by human cervical carcinoma HeLa cells at three cell cycle phases (G₀/G₁, S and G₂/M), and on their different internalization pathways and translocations in cells. The results show that HeLa cells could internalize both CDots by different pathways, with an overall slightly higher internalization efficiency for PEI-CDots. The presence of serum in culture media could have major effects, significantly enhancing the cellular uptake of EPA-CDots, yet markedly inhibiting that of PEI-CDots. The HeLa cells at different cell cycle phases have different behaviors in taking up the CDots, which are also affected by the different dot surface moieties and serum in culture media. Mechanistic implications of the results and the opportunities associated with an improved understanding on the cellular behaviors of CDots for potentially the manipulation and control of their cellular uptakes and translocations are discussed.

How to Study the Uptake and Toxicity of Nanoparticles in Cultured Brain Cells: The Dos and Don't Forgets

Due to their exciting properties, engineered nanoparticles have obtained substantial attention over the last two decades. As many types of nanoparticles are already used for technical and biomedical applications, the chances that cells in the brain will encounter nanoparticles have strongly increased. To test for potential consequences of an exposure of brain cells to engineered nanoparticles, cell culture models for different types of neural cells are frequently used. In this review article we will discuss experimental strategies and important controls that should be used to investigate the physicochemical properties of nanoparticles for the cell incubation conditions applied as well as for studies on the biocompatibility and the cellular uptake of nanoparticles in neural cells. The main focus of this article will be the interaction of cultured neural cells with iron oxide nanoparticles, but similar considerations are important for studying the consequences of an exposure of other types of cultured cells with other types of nanoparticles. Our article aims to improve the understanding of the special technical challenges of working with nanoparticles on cultured neural cells, to identify potential artifacts and to prevent misinterpretation of data on the potential adverse or beneficial consequences of a treatment of cultured cells with nanoparticles.

The Advancing of Zinc Oxide Nanoparticles for Biomedical Applications

Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of industrial products such as rubber, paint, coating, and cosmetics. In the past two decades, ZnO NPs have become one of the most popular metal oxide nanoparticles in biological applications due to their excellent biocompatibility, economic, and low toxicity. ZnO NPs have emerged a promising potential in biomedicine, especially in the fields of anticancer and antibacterial fields, which are involved with their potent ability to trigger excess reactive oxygen species (ROS) production, release zinc ions, and induce cell apoptosis. In addition, zinc is well known to keep the structural integrity of insulin. So, ZnO NPs also have been effectively developed for antidiabetic treatment. Moreover, ZnO NPs show excellent luminescent properties and have turned them into one of the main candidates for bioimaging. Here, we summarize the synthesis and recent advances of ZnO NPs in the biomedical fields, which will be helpful for facilitating their future research progress and focusing on biomedical fields.

Monitoring characteristics and genotoxic effects of engineered nanoparticle-protein corona

Engineered nanoparticles (ENPs) possess different physical and chemical properties compared to their bulk counterparts. These unique properties have found application in various products in the area of therapeutics, consumer goods, environmental remediation, optical and electronic fields. This has also increased the likelihood of their release into the environment thereby affecting human health and ecosystem. ENPs, when in contact with the biological system have various physical and chemical interactions with cellular macromolecules including proteins. These interactions lead to the formation of protein corona around the ENPs. Consequently, living systems interact with the protein-coated ENP rather than with a bare ENP. This ENP-protein interaction influences uptake, accumulation, distribution and clearance and thereby affecting the cytotoxic and genotoxic responses. Although there are few studies which discussed the fate of ENPs, there is a need for extensive research in the field of ENPs, to understand the interaction of ENPs with biological systems for their safe and productive application.

Role of modification route for zinc oxide nanoparticles on protein structure and their effects on glioblastoma cells

Zinc oxide nanoparticles (ZnO) are presented as potential cancer therapeutic agent based on their surface properties. In this study, the most abundant blood proteins, albumin, fibrinogen and apo-transferrin, were covalently bound (c-ZnO NPs) and nonspecifically adsorbed (n-ZnO NPs) onto ZnO NPs to evaluate the role of modification route on protein structure and their effects on glioblastoma cells. The success of modification and structures of proteins on ZnO NPs were characterized with FT-IR. It was found that non-covalent interaction significantly damaged the secondary structure of proteins compared to those covalently attached to the ZnO nanoparticle. The effects of modified ZnO NPs were investigated by evaluating viability, cycle, and death mechanisms of glioblastoma (U373) cells. n-ZnO NPs were found more toxic compared to the pristine and c-ZnO NPs. However, c-ZnO NPs with albumin and apo-transferrin both perturbed the cell cycle function, and decreased the necrotic cell death rate of U373 cells below toxic concentration, suggesting their potential curative effect on glioblastoma cells.

Formulation of vitamin D encapsulated cinnamon oil nanoemulsion: Its potential anti-cancerous activity in human alveolar carcinoma cells

Cinnamon oil is used for medicinal purpose since ancient time because of its antioxidant activity. Oil-in-water nanoemulsion (NE) of cinnamon oil was formulated using cinnamon oil, nonionic surfactant Tween 80 and water by ultrasonication technique. Phase diagram was constructed to investigate the influence of oil, water and surfactant concentration. Vitamin D encapsulated cinnamon oil NE was fabricated by wash out method followed by ultrasonication in similar fashion. The hydrodynamic size of cinnamon oil NE and vitamin D encapsulated cinnamon oil NE was observed as 40.52 and 48.96 nm in complete DMEM F12 media respectively. We focused on the cytotoxic and genotoxic responses of NEs in A549 cells in concentration dependent manner. We observed that both NEs induce DNA damage along with corresponding increase in micronucleus frequency that is evident from the comet and CBMN assay. Both the NEs arrested the cell cycle progression in G0/G1 phase, showed increased expression of Bax, capase-3 and caspase-9 and decrease expression of BcL2 proteins along with significant (p < 0.05) increase in apoptotic cell population and loss of mitochondrial membrane potential. NEs were also evaluated for bactericidal efficacy against E. coli. Thus, both NEs have cytotoxic, genotoxic and antibacterial potential and hence can also be used in food industry with cinnamon oil as carrier for lipophilic nutraceutical like vitamin D.

Molecular Mechanisms of Zinc Oxide Nanoparticle-Induced Genotoxicity Short Running Title: Genotoxicity of ZnO NPs

Background: Zinc oxide nanoparticles (ZnO NPs) are among the most frequently applied nanomaterials in consumer products. Evidence exists regarding the cytotoxic effects of ZnO NPs in mammalian cells; however, knowledge about the potential genotoxicity of ZnO NPs is rare, and results presented in the current literature are inconsistent. Objectives: The aim of this review is to summarize the existing data regarding the DNA damage that ZnO NPs induce, and focus on the possible molecular mechanisms underlying genotoxic events. Methods: Electronic literature databases were systematically searched for studies that report on the genotoxicity of ZnO NPs. Results: Several methods and different endpoints demonstrate the genotoxic potential of ZnO NPs. Most publications describe in vitro assessments of the oxidative DNA damage triggered by dissoluted Zn²⁺ ions. Most genotoxicological investigations of ZnO NPs address acute exposure situations. Conclusion: Existing evidence indicates that ZnO NPs possibly have the potential to damage DNA. However, there is a lack of long-term exposure experiments that clarify the intracellular bioaccumulation of ZnO NPs and the possible mechanisms of DNA repair and cell survival.

The Toxicity of Nanoparticles Depends on Multiple Molecular and Physicochemical Mechanisms

Nanotechnology is an emerging discipline that studies matters at the nanoscale level. Eventually, the goal is to manipulate matters at the atomic level to serve mankind. One growing area in nanotechnology is biomedical applications, which involve disease management and the discovery of basic biological principles. In this review, we discuss characteristics of nanomaterials, with an emphasis on transition metal oxide nanoparticles that influence cytotoxicity. Identification of those properties may lead to the design of more efficient and safer nanosized products for various industrial purposes and provide guidance for assessment of human and environmental health risk. We then investigate biochemical and molecular mechanisms of cytotoxicity that include oxidative stress-induced cellular events and alteration of the pathways pertaining to intracellular calcium homeostasis. All the stresses lead to cell injuries and death. Furthermore, as exposure to nanoparticles results in deregulation of the cell cycle (i.e., interfering with cell proliferation), the change in cell number is a function of cell killing and the suppression of cell proliferation. Collectively, the review article provides insights into the complexity of nanotoxicology.

Cell-cycle-specific Cellular Responses to Sonoporation

Microbubble-mediated sonoporation has shown its great potential in facilitating intracellular uptake of gene/drugs and other therapeutic agents that are otherwise difficult to enter cells. However, the biophysical mechanisms underlying microbubble-cell interactions remain unclear. Particularly, it is still a major challenge to get a comprehensive understanding of the impact of cell cycle phase on the cellular responses simultaneously occurring in cell membrane and cytoskeleton induced by microbubble sonoporation. Methods: Here, efficient synchronizations were performed to arrest human cervical epithelial carcinoma (HeLa) cells in individual cycle phases. The, topography and stiffness of synchronized cells were examined using atomic force microscopy. The variations in cell membrane permeabilization and cytoskeleton arrangement induced by sonoporation were analyzed simultaneously by a real-time fluorescence imaging system. Results: The results showed that G1-phase cells typically had the largest height and elastic modulus, while S-phase cells were generally the flattest and softest ones. Consequently, the S-Phase was found to be the preferred cycle for instantaneous sonoporation treatment, due to the greatest enhancement of membrane permeability and the fastest cytoskeleton disassembly at the early stage after sonoporation. Conclusion: The current findings may benefit ongoing efforts aiming to pursue rational utilization of microbubble-mediated sonoporation in cell cycle-targeted gene/drug delivery for cancer therapy.

Graphene oxide and reduced graphene oxide induced neural pheochromocytoma-derived PC12 cell lines apoptosis and cell cycle alterations via the ERK signaling pathways

Given the novel applications of graphene materials in biomedical and electronics industry, the health hazards of these particles have attracted extensive worldwide attention. Although many studies have been performed on graphene material-induced toxic effects, toxicological data for the effect of graphene materials on the nervous system are lacking. In this study, we focused on the biological effects of graphene oxide (GO) and reduced graphene oxide (rGO) materials on PC12 cells, a type of traditional neural cell line. We found that GO and rGO exerted significant toxic effects on PC12 cells in a dose- and time-dependent manner. Moreover, apoptosis appeared to be a response to toxicity. A potent increase in the number of PC12 cells at G0/G1 phase after GO and rGO exposure was detected by cell cycle analysis. We found that phosphorylation levels of ERK signaling molecules, which are related to cell cycle regulation and apoptosis, were significantly altered after GO and rGO exposure. In conclusion, our results show that GO has more potent toxic effects than rGO and that apoptosis and cell cycle arrest are the main toxicity responses to GO and rGO treatments, which are likely due to ERK pathway regulation.

Zinc Oxide Nanoparticles Influence Microflora in Ileal Digesta and Correlate Well with Blood Metabolites

Zinc oxide nanoparticles (ZnO NPs) are used widely in consumer and industrial products, however, their influence on gut microbiota and metabolism and their mutual interactions are not fully understood. In this study, the effects of ZnO NPs on ileal bacterial communities, plasma metabolites, and correlations between them were investigated. Hens were fed with different concentrations of ZnO NPs [based on Zn; 0 mg/kg (control), 25 mg/kg, 50 mg/kg, and 100 mg/kg] for 9 weeks. Subsequently, ileal digesta and blood plasma were collected for analysis of microflora and metabolites, respectively. The V3-V4 region of the 16S rRNA gene of ileal digesta microbiota was sequenced using the Illumina HiSeq 2500 platform. The predominant bacterial community in the ileum belongs to the phylum Firmicutes. The richness of the bacterial community was negatively correlated with increasing amounts of ZnO NPs (r = -0.636, P < 0.01); when ZnO NP levels were at 100 mg/kg, microbiota diversity was significantly decreased (P < 0.05). The community structure determined by LEfSe analysis indicated that Bacilli, Fusobacteria, and Proteobacteria were changed, and Lactobacillus was reduced by ZnO NPs. Moreover, metabolism as analyzed by nuclear magnetic resonance (NMR) indicated that glucose, some amino acids, and other metabolites were changed by ZnO NPs. Choline, lactate, and methionine were positively correlated with bacterial richness. In summary, ZnO NPs could influence the levels of microflora in ileal digesta, particularly Lactobacillus. Furthermore, the richness of the microbiota was related to changes in choline, lactate, and methionine metabolism.

Cyto-genotoxicity and oxidative stress induced by zinc oxide nanoparticle in human lymphocyte cells in vitro and Swiss albino male mice in vivo

ZnO-np has immense potential and application in cosmetic and health care sectors. Hence it was imperative to assess the toxicity/safety of these nanoparticles. In this study, we have evaluated the effects of ZnO-np in human peripheral blood mononuclear cells (PBMCs) in vitro and in Swiss albino male mice in vivo for cyto-genotoxicity and oxidative damage. In vitro results showed that ZnO-nps were weakly genotoxic, induced significant decrease in mitochondrial membrane potential and was capable of ROS generation, leading to apoptosis. In bone marrow cells in vivo, reduction of mitochondrial membrane potential (MMP), increased oxidative stress and G0/G1 cell cycle arrest was observed along with chromosome aberrations and micronuclei formation. In liver cells DNA damage and induction of oxidative stress with concurrent decrease in inhibition of antioxidant enzymes were noted. These in vitro and in vivo results demonstrated that ZnO-np induced genotoxic response and ROS production leading to apoptotic cell death and established a good co-relation between the two biological systems. More importantly, the results stress on the need of multiple endpoint assay-approaches, with an in vitro-in vivo study design to assess nanoparticle toxicology.