Size-dependent cytotoxicity of amorphous silica nanoparticles in human hepatoma HepG2 cells

Global metabolomics approach in in vitro and in vivo models reveals hepatic glutathione depletion induced by amorphous silica nanoparticles

The present study aimed to investigate the mechanisms involved in amorphous silica nanoparticles (aSiNPs)-mediated hepatotoxicity through the evaluation of changes in global metabolomics in in vitro and in vivo systems. ¹H NMR-based non-targeted global metabolomics and biochemical approaches were conducted in an aSiNPs-treated human hepatoma cell line (HepG2) and in ICR mice liver. The non-targeted NMR-based metabolomic analysis, followed by pathway analysis, revealed the perturbation of glutathione metabolism and the depletion of the glutathione pool after aSiNPs treatment in both in vitro (HepG2 cells) and in vivo systems. The total glutathione level, glutathione-S-transferase enzyme activity, and antioxidant gene expression strongly corroborated the metabolomic analysis results. The in vitro results were further supported by the in vivo data, specifically for metabolites profiling (Pearson Correlation coefficient is 0.462 (p = 0.026)). Furthermore, the depletion of glutathione, the formation of NADPH oxidase-mediated reactive oxygen species, and oxidative stress were evident in aSiNPs-treated HepG2 cells. Overall, the suppression of glutathione metabolism and oxidative stress are among the principal causes of aSiNPs-mediated hepatotoxicity.

Molecular Mechanism of Modified Clay Controlling the Brown Tide Organism Aureococcus anophagefferens Revealed by Transcriptome Analysis

The data and experiences in mitigating harmful algal blooms (HABs) by modified clay (MC) show that a bloom does not continue after the dispersal of the MC, even though the density of the residual cells in the water is still high, at 20-30% of the initial cell density. This interesting phenomenon indicates that in addition to flocculation, MC has an additional control mechanism. Here, transcriptome sequencing technology was used to study the molecular mechanism of MC in controlling HABs. In residual cells treated with MC, the photosynthetic light reaction was the most affected physiological process. Some genes related to the light harvesting complex, photosystem (PS) I and PS II, were significantly up-regulated ( p < 0.05), and several transcripts increased by as much as 6-fold. In contrast, genes associated with the dark reaction did not significantly change. In addition to genes associated with photosynthesis, numerous genes related to energy metabolism, stress adaptation, cytoskeletal functioning, and cell division also responded to MC treatment. These results indicated that following treatment with MC, the normal physiological processes of algal cells were disrupted, which inhibited cell proliferation and growth. Thus, these findings provide scientific proof that HABs are controlled by MC.

Isolation and Structural Characterization of a Second Polysaccharide from Bulbs of Lanzhou Lily

In this study, a second water-soluble polysaccharide (designated as LDP-2) was isolated from the bulbs of Lanzhou Lily (Lilium davidii var. unicolor). Based on monosaccharide composition and methylation analysis, its structural features were investigated using a variety of characterizations, such as size-exclusion chromatography combined with laser light scattering (SEC-LLS), gas chromatography-mass spectroscopy (GC-MS), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that LDP-2 is a homogeneous heteropolysaccharide (molecular weight 6.2 × 10⁴ Da), which includes four kinds of monosaccharides (Lyx, Man, Glc, and Gal in an approximate weight ratio of 6.74: 6.28: 76.50: 10.48). Furthermore, its morphology, thermal behavior, and preliminary hypoglycemic activities were also investigated.

Biodegradable Nanoparticles Enhanced Adhesiveness of Mussel-Like Hydrogels at Tissue Interface

Popular bioadhesives, such as fibrin, cyanoacrylate, and albumin-glutaraldehyde based materials, have been applied for clinical applications in wound healing, drug delivery, and bone and soft tissue engineering; however, their performances are limited by weak adhesion strength and rapid degradation. In this study a mussel-inspired, nanocomposite-based, biodegradable tissue adhesive is developed by blending poly(lactic-co-glycolic acid) (PLGA) or N-hydroxysuccinimide modified PLGA nanoparticles (PLGA-NHS) with mussel-inspired alginate-dopamine polymer (Alg-Dopa). Adhesive strength measurement of the nanocomposites on porcine skin-muscle constructs reveals that the incorporation of nanoparticles in Alg-Dopa significantly enhances the tissue adhesive strength compared to the mussel-inspired adhesive alone. The nanocomposite formed by PLGA-NHS nanoparticles shows higher lap shear strength of 33 ± 3 kPa, compared to that of Alg-Dopa hydrogel alone (14 ± 2 kPa). In addition, these nanocomposites are degradable and cytocompatible in vitro, and elicit in vivo minimal inflammatory responses in a rat model, suggesting clinical potential of these nanocomposites as bioadhesives.

HER2-Targeted Multifunctional Silica Nanoparticles Specifically Enhance the Radiosensitivity of HER2-Overexpressing Breast Cancer Cells

We investigated the effects of targeted functionalized silica nanoparticles on the radiosensitivity of cancer cells. Better control of the local concentration of silica nanoparticles may facilitate their use as an adjuvant in conjunction with ionizing radiation to target cancer cells while preventing damage to normal cells. Hyperbranched polyamidoamine (PAMAM) was grafted onto the surface of amorphous silica nanoparticles to functionalize them. The PAMAM-coated silica nanoparticles (PCSNs) were then conjugated with fluorescent dyes. Anti-HER2 antibodies were covalently attached to the labeled PCSNs. The HER2-overexpressing SK-BR3 breast cancer cell line was incubated in medium containing the PCSN probes. After incubation; the cells were exposed to X-ray radiation. Cells were counted in all samples using cell proliferation assays; and apoptotic cells were detected. The cell survival results showed that the combination of the targeted PCSN probes and radiation reduced the survival rate of SK-BR3 cells to a greater extent than when either PCSN probes, PCSNs or radiation were applied individually. The results also showed an increase in apoptosis in the SK-BR3 cells that internalized the PCSN probes and were then irradiated. Based on these data, PCSN probes act as specific radiosensitizing agents for HER2-overexpressing cells.

Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media

β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3H, 35S, and 33P, important biological isotopes, is challenging due to the low energies (Emax ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3H, 35S, and 33P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3H, 8 nCi/mL for 35S, and <1 nCi/mL for 33P.

Cellular pathways involved in silica nanoparticles induced apoptosis: A systematic review of in vitro studies

Silica nanoparticles (SiNPs) have been found to pass through biological barriers and get distributed in the human body. They induce cell apoptosis via various mechanisms in body organs. To understand these mechanisms, we carried out systematic review of in vitro studies on SiNPs-induced cell apoptosis. Office of Health Assessment and Translation approach for Systematic Review and Evidence Integration was used to identify 14 studies dating from the year 2000 to current. Four studies showed an increase in DNA damage, cell cycle arrest, proapoptotic factors and decrease in antiapoptotic factors resulting to apoptosis. Eight studies showed induction of mitochondrial dysfunction, Bax upregulation, Bcl-2 downregulation, and caspase-3, -7, -9 activities increase. Increase in FADD, TNFR1 and Bid proteins was observed in one study, while the other NO production and caspase-3 activity was increased. These studies found the potency of SiNPs to induce cell apoptosis through DNA damage, mitochondrial, tumor necrosis factor, and nitric oxide related pathways.

Effect of Crystal Shape and Aggregation of Calcium Oxalate Monohydrate on Cellular Toxicity in Renal Epithelial Cells

Renal epithelial cell injury is a key step in inducing kidney stone formation. This injury induced by crystallites with different shapes and aggregation states has been receiving minimal research attention. To compare the shape and aggregation effects of calcium oxalate crystals on their toxicity, we prepared calcium oxalate monohydrate (COM) crystals with the morphology of a hexagonal lozenge, a thin hexagonal lozenge, and their corresponding aggregates. We then compared their toxicities toward human kidney proximal tubular epithelial (HK-2) cells. All four shapes of COM crystals caused cell-membrane rupture, upregulated intracellular reactive oxygen, and decreased mitochondrial membrane potential. This series of phenomena ultimately led to necrotic cell death. The overall damage in cells was determined in terms of both exterior and interior damage. Crystals with a large Ca2+ ion-rich (1̅01) active face showed the greatest toxicity in HK-2 cells and the largest extent of adhesion onto the cell surface. Crystals with sharp edges easily caused cell-membrane ruptures. The aggregation of sharp crystals aggravated cell injury, whereas the aggregation of blunt crystals weakened cell injury. Therefore, crystal shapes and aggregation states were important factors that affected crystal toxicity in renal epithelial cells. All of these findings elucidated the relationship between the physical properties of crystals and cytotoxicity and provided theoretical references for inhibiting stone formation.

Toxicology of silica nanoparticles: an update

Large-scale production and use of amorphous silica nanoparticles (SiNPs) have increased the risk of human exposure to SiNPs, while their health effects remain unclear. In this review, scientific papers from 2010 to 2016 were systematically selected and sorted based on in vitro and in vivo studies: to provide an update on SiNPs toxicity and to address the knowledge gaps indicated in the review of Napierska (Part Fibre Toxicol 7:39, 2010). Toxicity of SiNPs in vitro is size, dose, and cell type dependent. SiNPs synthesized by wet route exhibited noticeably different biological effects compared to thermal route-based SiNPs. Amorphous SiNPs (particularly colloidal and stöber) induced toxicity via mechanisms similar to crystalline silica. In vivo, route of administration and physico-chemical properties of SiNPs influences the toxicokinetics. Adverse effects were mainly observed in acutely exposed animals, while no significant signs of toxicity were noted in chronically dosed animals. The correlation between in vitro and in vivo toxicity remains less well established mainly due to improper-unrealistic-dosing both in vitro and in vivo. In conclusion, notwithstanding the multiple studies published in recent years, unambiguous linking of physico-chemical properties of SiNPs types to toxicity, bioavailability, or human health effects is not yet possible.

Silica nanoparticles induce liver fibrosis via TGF-β1/Smad3 pathway in ICR mice

The liver is one of the target organs of silica nanoparticles (SiO₂ NPs) but the toxic mechanism on the liver still remains unclear. This study aimed to explore the hepatic toxicity and its mechanism through repeated intravenous exposure to SiO₂ NPs in ICR mice. Results indicated that SiO₂ NPs could be distributed in hepatocytes, Kupffer cells, and hepatic stellate cells, and induce hepatic dysfunction as well as granuloma formation in the liver. The increase of lipid peroxide level and decrease of antioxidant enzyme activities in the liver indicated that SiO₂ NPs could induce hepatic oxidative damage. SiO₂ NPs induced hepatocytes’ apoptosis shown by morphological examination and TUNEL assay. The results of Masson’s trichrome staining and hydroxyproline assay showed hyperplasia of collagen fibers in the liver, suggesting SiO₂ NPs caused liver fibrosis, and it was promoted by oxidative damage and hepatocytes’ apoptosis. The results of Western blot analysis and immunohistochemical staining indicated that the activation of TGF-β₁/Smad3 signaling pathway played an important role in this pathophysiological process. The results suggested that oxidative damage and hepatocyte apoptosis activated TGF-β₁/Smad3 signaling pathway, and thus promoted the process of liver fibrosis induced by intravenous injection of SiO₂ NPs in mice. This study, for the first time, investigated liver fibrosis and its related mechanism induced by repeated intravenous exposure of amorphous SiO₂ NPs, and provides important experimental evidence for safety evaluation of SiO₂ NPs, especially in biomedical application.

Silica nanoparticles induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway

The present study was to investigate effects of Silica nanoparticles (SiNPs) on nervous system and explore potential mechanisms in human neuroblastoma cells (SH-SY5Y). Cytotoxicity was detected by cell viability and Lactate dehydrogenase (LDH) release. Flow cytometry analysis was applied to assess mitochondrial membrane potential (MMP) loss, intracellular Ca²⁺ and apoptosis. To clarify the mechanism of SiNPs-induced apoptosis, intrinsic apoptosis-related proteins were detected. Our results showed that SiNPs caused cytotoxicity, cell membrane damage and Ca²⁺ increase in a dose-dependent manner in SH-SY5Y cells. Both the mitochondrial membrane potential (MMP) loss and potential mitochondria damage resulted in Cyt C release to the cytoplasm. The elevated Cyt C and Apaf1 further triggered intrinsic apoptosis via executive molecular caspase-9 and caspase-3. The present study confirmed that SiNPs induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway and provided a better understanding of the potential toxicity induced by SiNPs on human neurocyte.

In vivo toxicologic study of larger silica nanoparticles in mice

Silica nanoparticles (SiNPs) are being studied and used for medical purposes. As nanotechnology grows rapidly, its biosafety and toxicity have frequently raised concerns. However, diverse results have been reported about the safety of SiNPs; several studies reported that smaller particles might exhibit toxic effects to some cell lines, and larger particles of 100 nm were reported to be genotoxic to the cocultured cells. Here, we investigated the in vivo toxicity of SiNPs of 150 nm in various dosages via intravenous administration in mice. The mice were observed for 14 days before blood examination and histopathological assay. All the mice survived and behaved normally after the administration of nanoparticles. No significant weight change was noted. Blood examinations showed no definite systemic dysfunction of organ systems. Histopathological studies of vital organs confirmed no SiNP-related adverse effects. We concluded that 150 nm SiNPs were biocompatible and safe for in vivo use in mice.

Inhibition of gap junction intercellular communication is involved in silica nanoparticles-induced H9c2 cardiomyocytes apoptosis via the mitochondrial pathway

Gap junction intercellular communication (GJIC) between cardiomyocytes is essential for synchronous heart contraction and relies on connexin-containing channels. Connexin 43 (Cx43) is a major component involved in GJIC in heart tissue, and its abnormal expression is closely associated with various cardiac diseases. Silica nanoparticles (SNPs) are known to induce cardiovascular toxicity. However, the mechanisms through which GJIC plays a role in cardiomyocytes apoptosis induced by SNPs remain unknown. The aim of the present study is to determine whether SNPs-decreased GJIC promotes apoptosis in rat cardiomyocytes cell line (H9c2 cells) via the mitochondrial pathway using CCK-8 Kit, scrape-loading dye transfer technique, Annexin V/PI double-staining assays, and Western blot analysis. The results showed that SNPs elicited cytotoxicity in H9c2 cells in a time- and concentration-dependent manner. SNPs also reduced GJIC in H9c2 cells in a concentration-dependent manner through downregulation of Cx43 and upregulation of P-Cx43. Inhibition of gap junctions by gap junction blocker carbenoxolone disodium resulted in decreased survival and increased apoptosis, whereas enhancement of the gap junctions by retinoic acid led to enhanced survival but decreased apoptosis. Furthermore, SNPs-induced apoptosis through the disrupted functional gap junction was correlated with abnormal expressions of the proteins involved in the mitochondrial pathway-related apoptosis such as Bcl-2/Bax, cytochrome C, Caspase-9, and Caspase-3. Taken together, our results provide the first evidence that SNPs-decreased GJIC promotes apoptosis in cardiomyocytes via the mitochondrial pathway. In addition, downregulation of GJIC by SNPs in cardiomyocytes is mediated through downregulation of Cx43 and upregulation of P-Cx43. These results suggest that in rat cardiomyocytes cell line, GJIC plays a protective role in SNPs-induced apoptosis and that GJIC may be one of the targets for SNPs-induced biological effects.

New findings of silica nanoparticles induced ER autophagy in human colon cancer cell

Nanoparticle-induced autophagy has been extensively studied, however, real time information about the endoplasmic reticulum involved autophagic process (ER autophagy) induced by nanomaterials remains unknown. In this work, silica nanoparticles (SNPs) were synthesized with characteristics of low toxicity, good biocompatibility and excellent water dispersibility to treat cells. Results show that either low concentration (10 μg/mL) or high concentration (200 μg/mL) of SNPs could increase the quantity of processing from microtubule-associated protein 1-light chain 3-I (LC3-I) to the other variant of LC3 (LC3-II). Interestingly, the level of autophagy induced by the SNPs is associated with the treated time but not the concentrations of SNPs. Importantly, for the first time, SNP accumulation in ER was discovered through co-localization analysis, which incurs ER autophagy. These new findings about SNPs-induced ER autophagy could open an effective way for securely designing silica-based nanoparticles and enable us to know more about ER autophagy.

Assessment of Pulmonary Toxicity Induced by Inhaled Toner with External Additives

We investigated the harmful effects of exposure to a toner with external additives by a long-term inhalation study using rats, examining pulmonary inflammation, oxidative stress, and histopathological changes in the lung. Wistar rats were exposed to a well-dispersed toner (mean of MMAD: 2.1 μm) at three mass concentrations of 1, 4, and 16 mg/m³ for 22.5 months, and the rats were sacrificed after 6 months, 12 months, and 22.5 months of exposure. The low and medium concentrations did not induce statistically significant pulmonary inflammation, but the high concentration did, and, in addition, a histopathological examination showed fibrosis in the lung. Although lung tumor was observed in one sample of high exposure for 22.5 months, the cause was not statistically significant. On the other hand, a persistent increase in 8-OHdG was observed in the high exposure group, indicating that DNA damage by oxidative stress with persistent inflammation leads to the formation of tumorigenesis. The results of our studies show that toners with external additives lead to pulmonary inflammation, oxidative stress, and fibrosis only at lung burdens beyond overload. These data suggest that toners with external additives may have low toxicity in the lung.

Oxidative Damage and Energy Metabolism Disorder Contribute to the Hemolytic Effect of Amorphous Silica Nanoparticles

Amorphous silica nanoparticles (SiNPs) have been extensively used in biomedical applications due to their particular characteristics. The increased environmental and iatrogenic exposure of SiNPs gained great concerns on the biocompatibility and hematotoxicity of SiNPs. However, the studies on the hemolytic effects of amorphous SiNPs in human erythrocytes are still limited. In this study, amorphous SiNPs with 58 nm were selected and incubated with human erythrocytes for different times (30 min and 2 h) at various concentrations (0, 10, 20, 50, and 100 μg/mL). SiNPs induced a dose-dependent increase in percent hemolysis and significantly increased the malondialdehyde (MDA) content and decreased the superoxide dismutase (SOD) activity, leading to oxidative damage in erythrocytes. Hydroxyl radical (·OH) levels were detected by electron spin resonance (ESR), and the decreased elimination rates of ·OH showed SiNPs induced low antioxidant ability in human erythrocytes. Na(+)-K(+) ATPase activity and Ca(2+)-Mg(2+) ATPase activity were found remarkably inhibited after SiNP treatment, possibly causing energy sufficient in erythrocytes. Percent hemolysis of SiNPs was significantly decreased in the presence of N-acetyl-cysteine (NAC) and adenosine diphosphate (ADP). It was concluded that amorphous SiNPs caused dose-dependent hemolytic effects in human erythrocytes. Oxidative damage and energy metabolism disorder contributed to the hemolytic effects of SiNPs in vitro.

Cytotoxicity study of Piper nigrum seed mediated synthesized SnO2 nanoparticles towards colorectal (HCT116) and lung cancer (A549) cell lines

Different sized tetragonal tin oxide nanoparticles (SnO₂ NPs) were synthesized using Piper nigrum seed extract at three different calcination temperatures (300, 500, 900°C) and these nanoparticles (NPs) were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS) and Fourier transform infrared spectrophotometry (FT-IR). The optical properties were studied using UV-Vis and photoluminescence (PL) spectrophotometers. The generation of reactive oxygen species (ROS) was monitored by using a fluorescence spectrophotometer and fluorescence microscope. The cytotoxicity of the synthesized SnO₂ NPs was checked against the colorectal (HCT116) and lung (A549) cancer cell lines and the study results show that SnO₂ NPs were toxic against cancer cell lines depending on their size and dose. IC₅₀ values of SnO₂ NPs having average particle sizes of 8.85±3.5, 12.76±3.9 and 29.29±10.9nm are 165, 174 and 208μgL^-1 against HCT116, while these values are 135, 157 and 187μgL^-1 against A549 carcinoma cell lines, respectively. The generated ROS were responsible for the cytotoxicity of SnO₂ NPs to the studied cancer cells and smaller size NPs generated more ROS and hence showed higher cytotoxicity over larger size NPs. The results of this study suggest that the synthesized stable nanoparticles could be a potent therapeutic agent towards cancerous cell lines.

In Vitro Cytotoxicity of Nanoparticles: A Comparison between Particle Size and Cell Type

The reduction in size of Zinc oxide (ZnO) and Silicon dioxide (SiO2) particles from micron to nano scale offers unique physical characteristics on one hand while making them cytotoxic on other hand. The present study was aimed at comparing cytotoxic effects of ZnO and SiO2 nanoparticles with their micron size and secondary aim was to compare responses of these particles to two different cell types, namely, human lung epithelial cells (L-132) and human monocytes (THP-1). The L-132 and THP-1 cells were exposed to nano and micron size of ZnO and SiO2 particles with different concentrations (5–500 μg/mL) for 24 h, and cytotoxicity was analyzed by MTT assay, live-dead staining, and TC-50 was calculated. ZnO and SiO2 particles showed concentration-dependent cytotoxicity in both cell lines. In size-dependent study, ZnO particles exhibited nearly equal toxicity profile in L-132 cells while in THP-1 cells nano ZnO showed more toxicity than its micron size. The SiO2 particles showed more toxicity in their nano size than micron size in both cell lines. Human monocytes, THP-1 cells, were more sensitive towards the toxicity of both particles than human lung cells, L-132. The results highlight the difference of cytotoxicity between particle sizes and differential sensitivity of cells towards the particles of same composition. In conclusion, ZnO and SiO2 particles exhibited concentration-dependent toxicity, which was more in their nano size than micron counterpart. However, the toxic response varies depending on type of cell exposed due to differential sensitivity.

Reinjury risk of nano-calcium oxalate monohydrate and calcium oxalate dihydrate crystals on injured renal epithelial cells: aggravation of crystal adhesion and aggregation

BACKGROUND

Renal epithelial cell injury facilitates crystal adhesion to cell surface and serves as a key step in renal stone formation. However, the effects of cell injury on the adhesion of nano-calcium oxalate crystals and the nano-crystal-induced reinjury risk of injured cells remain unclear.

METHODS

African green monkey renal epithelial (Vero) cells were injured with H2O2 to establish a cell injury model. Cell viability, superoxide dismutase (SOD) activity, malonaldehyde (MDA) content, propidium iodide staining, hematoxylin-eosin staining, reactive oxygen species production, and mitochondrial membrane potential (Δψm) were determined to examine cell injury during adhesion. Changes in the surface structure of H2O2-injured cells were assessed through atomic force microscopy. The altered expression of hyaluronan during adhesion was examined through laser scanning confocal microscopy. The adhesion of nano-calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) crystals to Vero cells was observed through scanning electron microscopy. Nano-COM and COD binding was quantitatively determined through inductively coupled plasma emission spectrometry.

RESULTS

The expression of hyaluronan on the cell surface was increased during wound healing because of Vero cell injury. The structure and function of the cell membrane were also altered by cell injury; thus, nano-crystal adhesion occurred. The ability of nano-COM to adhere to the injured Vero cells was higher than that of nano-COD crystals. The cell viability, SOD activity, and Δψm decreased when nano-crystals attached to the cell surface. By contrast, the MDA content, reactive oxygen species production, and cell death rate increased.

CONCLUSION

Cell injury contributes to crystal adhesion to Vero cell surface. The attached nano-COM and COD crystals can aggravate Vero cell injury. As a consequence, crystal adhesion and aggregation are enhanced. These findings provide further insights into kidney stone formation.

Silicon dioxide nanoparticles increase macrophage atherogenicity: Stimulation of cellular cytotoxicity, oxidative stress, and triglycerides accumulation

Nanoparticle research has focused on their toxicity in general, while increasing evidence points to additional specific adverse effects on atherosclerosis development. Arterial macrophage cholesterol and triglyceride (TG) accumulation and foam cell formation are the hallmark of early atherogenesis, leading to cardiovascular events. To investigate the in vitro atherogenic effects of silicon dioxide (SiO2 ), J774.1 cultured macrophages (murine cell line) were incubated with SiO2 nanoparticle (SP, d = 12 nm, 0-20 µg/mL), followed by cellular cytotoxicity, oxidative stress, TG and cholesterol metabolism analyses. A significant dose-dependent increase in oxidative stress (up to 164%), in cytotoxicity (up to 390% measured by lactate dehydrogenase (LDH) release), and in TG content (up to 63%) was observed in SiO2 exposed macrophages compared with control cells. A smaller increase in macrophage cholesterol mass (up to 22%) was noted. TG accumulation in macrophages was not due to a decrease in TG cell secretion or to an increased TG biosynthesis rate, but was the result of attenuated TG hydrolysis secondary to decreased lipase activity and both adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) protein expression (by 42 and 25%, respectively). Overall, SPs showed pro-atherogenic effects on macrophages as observed by cytotoxicity, increased oxidative stress and TG accumulation. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 713-723, 2016.

Autophagy and autophagy dysfunction contribute to apoptosis in HepG2 cells exposed to nanosilica

Great concerns have led to the evaluation of the potential hazards of nanosilica to human health and the environment. However, there still exists persistent debates on the biological effects and toxic consequences induced by nanosilica. The present study investigated both autophagy and apoptosis in ICR mice and Human hepatocellular carcinoma cells (HepG2), and then explored the interactive mechanism between these two distinct cell death modalities in HepG2 cells. Mice liver injuries seen by hematoxylin and eosin (HE) staining indicated the hepatotoxic effects of nanosilica. The TUNEL assay and immunohistochemistry results confirmed that nanosilica could induce both apoptosis and autophagy in vivo. Flow cytometry analysis demonstrated apoptosis induction in vitro, while autophagic ultrastructures, LC3-II expression and immunofluorescence clarified autophagy activation by nanosilica. Apoptosis suppression by the autophagy inhibitor of 3-methyladenine (3-MA) implied that autophagy was involved in apoptotic cell death. A mechanistic study verified that nanosilica induced autophagy via negative regulation of mammalian target of rapamycin (mTOR) signaling but not the Beclin-1 associated pathway. The enhancement of p62 accumulation and mTOR down-regulation might account for the molecular mechanism in contribution of autophagy to apoptosis. As an emerging new mechanism of nanomaterial toxicity, autophagy might be a more susceptive indicator for toxicological consequence evaluation in nanoparticle toxicity. The present study provides novel evidence to elucidate the toxicity mechanisms and may be beneficial to more rational applications of nanosilica in the future.

Characterization of in vitro genotoxic, cytotoxic and transcriptomic responses following exposures to amorphous silica of different sizes

The objectives of the present study were to investigate the underlying mechanisms of genetic and cellular toxicity induced by silica nanoparticles (SiNPs) and determine if such toxicity is influenced by particle size. Commercially available amorphous SiNPs (12 nm, 5-10 nm, and 10-15 nm) and micrometer sized (SiP2 μm) silica were characterised for size, chemical composition, and aggregation state. Mouse lung epithelial (FE1) cells derived from Muta™Mouse were exposed to various concentrations (12.5, 25, 50, 100 μg/ml) of SiNPs and SiP2 μm. Cellular viability, clonogenic potential, oxidative stress, micronucleus formation, and mutant frequency were measured at different post-exposure time points. Cellular internalization of particles was assessed using nanoscale hyperspectral microscopy. Biological pathway and functional perturbations were assessed using DNA microarrays. Detailed characterization of particles confirmed their size, purity, and uniform dispersion in the exposure medium. Decreased cellular viability was observed acutely at 24h at concentrations higher than 25 μg/ml for all particle types, with SiNPs being the most sensitive; loss of viability was surface area dependent at the lowest concentration tested. However, only SiNP12 showed poor long-term survival. A size-dependent increase in micronucleus formation was also observed for SiNPs. In contrast to the viability results, SiP2 μm exhibited the highest potential to induce oxidative stress compared to the SiNPs at all tested concentrations. Gene ontology and biological pathway analysis revealed significant changes in the expression of genes implicated in lysosomal functions in SiNP12-treated cells, which appear closely associated with higher SiNP12 internalization and lysosomal rearrangements in the cytoplasm of these cells. These results suggest that SiNPs induce cellular and genetic toxicity in a size-dependent manner and that the observed toxicity may be the results of higher particle internalization of smaller SiNP and subsequent lysosomal overload.

Amorphous silica nanoparticle-induced perturbation of cholesterol homeostasis as a function of surface area highlights safe-by-design implementation: an integrated multi-OMICS analysis

The systems toxicology approach revealed that the alterations of cholesterol biosynthesis were directly proportional with the surface area of amorphous silica nanoparticles (aSiNPs); the larger the surface area the higher the cholesterol level.

Silica Nanoparticles Induce Oxidative Stress and Autophagy but Not Apoptosis in the MRC-5 Cell Line

This study evaluated the in vitro effects of 62.5 µg/mL silica nanoparticles (SiO₂ NPs) on MRC-5 human lung fibroblast cells for 24, 48 and 72 h. The nanoparticles’ morphology, composition, and structure were investigated using high resolution transmission electron microscopy, selected area electron diffraction and X-ray diffraction. Our study showed a decreased cell viability and the induction of cellular oxidative stress as evidenced by an increased level of reactive oxygen species (ROS), carbonyl groups, and advanced oxidation protein products after 24, 48, and 72 h, as well as a decreased concentration of glutathione (GSH) and protein sulfhydryl groups. The protein expression of Hsp27, Hsp60, and Hsp90 decreased at all time intervals, while the level of protein Hsp70 remained unchanged during the exposure. Similarly, the expression of p53, MDM2 and Bcl-2 was significantly decreased for all time intervals, while the expression of Bax, a marker for apoptosis, was insignificantly downregulated. These results correlated with the increase of pro-caspase 3 expression. The role of autophagy in cellular response to SiO₂ NPs was demonstrated by a fluorescence-labeled method and by an increased level of LC3-II/LC3-I ratio. Taken together, our data suggested that SiO₂ NPs induced ROS-mediated autophagy in MRC-5 cells as a possible mechanism of cell survival.

Pooling and Analysis of Published in Vitro Data: A Proof of Concept Study for the Grouping of Nanoparticles

The study aim was to test the applicability of pooling of nanomaterials-induced in vitro data for identifying the toxic capacity of specific (SiO₂, TiO₂, ZnO, CuO, CeO₂ and carbon nanotubes, [CNT]) nanoparticles (NP) and to test the usefulness for grouping purposes. Publication selection was based on specific criteria regarding experimental conditions. Two relevant biological endpoints were selected; generation of intracellular reactive oxygen species (ROS) and viability above 90%. The correlations of the ROS ratios with the NP parameters' size, concentration, and exposure time were analysed. The obtained data sets were then analysed with multiple regression analysis of variance (ANOVA) and the Tukey post-hoc test. The results show that this method is applicable for the selected metal oxide NP, but might need reconsideration and a larger data set for CNT. Several statistically significant correlations and results were obtained, thus validating the method. Furthermore, the relevance of the combination of ROS release with a cell viability test was shown. The data also show that it is advisable to compare ROS production of professional phagocytic with non-phagocytic cells. In conclusion, this is the first systematic analysis showing that pooling of available data into groups is a useful method for evaluation of data regarding NP induced toxicity in vitro.

Protein Adsorption From Biofluids on Silica Nanoparticles: Corona Analysis as a Function of Particle Diameter and Porosity

A study on the adsorption of proteins from fetal bovine serum (FBS) on spherical dense and mesoporous silica nanoparticles with a wide range of diameters, from 70 to 900 nm, is presented. Monodisperse populations of particles with a range of diameters were obtained through modifications of the Stöber method. Extensive characterization of the particles was then performed using N2 physisorption, TEM, DLS, and ζ-potential. Following serum exposure, proteomic evaluation in concert with thermogravimetric analysis revealed the associated concentrations of each protein identified in the hard corona. Small particles adsorbed the largest amount of protein, due to their larger external surface area. Proteins with low molecular weights (<50 kDa) constituted the majority of the protein corona, totaling between 60 and 80% of the total mass of adsorbed protein. Here, the higher surface curvature of small particles favors the enrichment of smaller proteins. Porosity does not promote protein adsorption but improves deposition of the low molecular weight protein fraction due to the size-exclusion effect related to pore diameter. These results have important implications for the use of dense and porous silica nanoparticles in biomedical applications.

Analysis of the cytotoxicity of carbon-based nanoparticles, diamond and graphite, in human glioblastoma and hepatoma cell lines

Nanoparticles have attracted a great deal of attention as carriers for drug delivery to cancer cells. However, reports on their potential cytotoxicity raise questions of their safety and this matter needs attentive consideration. In this paper, for the first time, the cytotoxic effects of two carbon based nanoparticles, diamond and graphite, on glioblastoma and hepatoma cells were compared. First, we confirmed previous results that diamond nanoparticles are practically nontoxic. Second, graphite nanoparticles exhibited a negative impact on glioblastoma, but not on hepatoma cells. The studied carbon nanoparticles could be a potentially useful tool for therapeutics delivery to the brain tissue with minimal side effects on the hepatocytes. Furthermore, we showed the influence of the nanoparticles on the stable, fluorescently labeled tumor cell lines and concluded that the labeled cells are suitable for drug cytotoxicity tests.

Toxicity of silica nanoparticles depends on size, dose, and cell type

Monodisperse spherical silica nanoparticles (SNPs) with diameters of 20-200 nm were employed to study size, dose, and cell-type dependent cytotoxicity in A549 and HepG2 epithelial cells and NIH/3T3 fibroblasts. These uniform SNPs of precisely controlled sizes eliminated uncertainties arising from mixed sizes, and uniquely allowed the probing of effects entirely size-dependent. Cell viability, membrane disruption, oxidative stress, and cellular uptake were studied. The extent and mechanism of SNP cytotoxicity were found to be not only size and dose dependent, but also highly cell type dependent. Furthermore, the 60 nm SNPs exhibited highly unusual behavior in comparison to particles of other sizes tested, implying interesting possibilities for controlling cellular activities using nanoparticles. Specifically, the 60 nm SNPs were preferentially endocytosed by cells and, at high doses, caused a disproportionate decrease in cell viability. The present work may help elucidate certain contradictions among existing results on nanoparticle-induced cytotoxicity.

FROM THE CLINICAL EDITOR

Silica nanoparticles are being investigated in many research areas for their use in clinical applications. Nonetheless, the relationship between particle size and potential toxicity remains to be elucidated. In this article, the authors studied the biological effects of spherical SNPs with precise diameters between 20 and 200 nm on three different cell types and their results should provide more data on safety for better drug design.

Bio-templated bioactive glass particles with hierarchical macro-nano porous structure and drug delivery capability

Hierarchically porous bioactive glass particles (BGPs) were synthesized by a facile sol-gel process using pollen grains as the templates. The synthesized pollen-templated bioactive glass particles (PBGPs) exhibited dual macro-nano porous structure. The macro pores (∼ 1 μm) were inherited from the template of pollen grains while the nano pores (∼ 9.5 nm) were induced by the intrinsic mechanism of the sol-gel process. PBGPs possessed a high specific surface area (111.4m(2)/g) and pore volume (0.35 cm(3)/g). Hydroxyapatite (HA) formation on PBGPs was detected within 3 days after immersion in simulated body fluid (SBF). Due to their larger specific surface area and pore volume, PBGPs could be loaded with more tetracycline hydrochloride (TCH) than non-templated BGPs and conventional melt-derived 45S5 BGPs. In addition, PBGPs exhibited a low initial burst release (within 10% of the loaded amount) within 18 h and a sustained release with a two-stage release pattern for up to 6 days in phosphate buffered saline (PBS). The antibacterial assay confirmed that the TCH-loaded PBGPs could release TCH within 5 days, and the released TCH could reach the minimum inhibitory concentration (MIC) against Escherichia coli. MTT assay indicated that PBGPs showed non-cytotoxic effects toward human hepatocellular carcinoma (Hep G2) cells after co-culture for up to 72 h in vitro. These results showed that the biocompatible hierarchically macro-nano porous PBGPs are potential for bone regeneration and local drug delivery applications.

Comparison of cellular toxicity caused by ambient ultrafine particles and engineered metal oxide nanoparticles

Objective

The development of nanotechnology has spurred concerns about the health effects of exposure to nanoparticles (NPs) and ultrafine particles (UFPs). Toxicological data on NPs and UFPs may provide evidence to support the development of regulations to reduce the risk of particle exposure. We tried to provide fundamental data to determine differences in cytotoxicity induced by ambient UFPs and engineered metal oxide NPs (ZnO, NiO, and CeO₂).

Methods

UFPs were sampled by using of a nano micro-orifice uniform deposit impactor. Physicochemical characterization of the UFPs and nano metal oxide particles were studied by scanning electron microscopy and transmission electron microscopy. Cellular toxicity induced by the different particles was assessed by using of comprehensive approaches and compared after A549 cells were exposured to the particles.

Results

All of the measured particles could damage A549 cells at concentrations ranging from 25 to 200 μg/mL. The lowest survival ratio and the highest lactate dehydrogenase level were caused by nano-ZnO particles, but the highest levels of intracellular reactive oxygen species (ROS) and percentages of apoptosis were observed in cells treated with the soluble fraction of ambient fine particles (PM_1.8) at 200 μg/mL. Relatively high concentrations of anthropogenic metals, including Zn, Ni, Fe, and Cu, may be responsible for the higher toxicity of fine ambient particles compared with the ambient coarse particles and UFPs. The selected heavy metals (Zn, Ni, Fe, and Cu) were found to be located in the perinuclear and cytoplasmic areas of A549 cells. The distribution pattern of metals from ambient particles showed that distributions of the metals in A549 cells were not uniform and followed the pattern Cu > Zn > Fe > Ni, suggesting that Cu was absorbed by A549 cells more easily than the other metals.

Conclusions

Metal nanoparticles oxides and UFPs at low concentration could damage to cells, but the manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles. The local concentration effect of heavy metals in A549 cells, as well as the induction of oxidative stress by the particles, may be responsible for the damage observed to the cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-015-0082-8) contains supplementary material, which is available to authorized users.

Comparison of cellular toxicity caused by ambient ultrafine particles and engineered metal oxide nanoparticles

OBJECTIVE

The development of nanotechnology has spurred concerns about the health effects of exposure to nanoparticles (NPs) and ultrafine particles (UFPs). Toxicological data on NPs and UFPs may provide evidence to support the development of regulations to reduce the risk of particle exposure. We tried to provide fundamental data to determine differences in cytotoxicity induced by ambient UFPs and engineered metal oxide NPs (ZnO, NiO, and CeO2).

METHODS

UFPs were sampled by using of a nano micro-orifice uniform deposit impactor. Physicochemical characterization of the UFPs and nano metal oxide particles were studied by scanning electron microscopy and transmission electron microscopy. Cellular toxicity induced by the different particles was assessed by using of comprehensive approaches and compared after A549 cells were exposured to the particles.

RESULTS

All of the measured particles could damage A549 cells at concentrations ranging from 25 to 200 μg/mL. The lowest survival ratio and the highest lactate dehydrogenase level were caused by nano-ZnO particles, but the highest levels of intracellular reactive oxygen species (ROS) and percentages of apoptosis were observed in cells treated with the soluble fraction of ambient fine particles (PM1.8) at 200 μg/mL. Relatively high concentrations of anthropogenic metals, including Zn, Ni, Fe, and Cu, may be responsible for the higher toxicity of fine ambient particles compared with the ambient coarse particles and UFPs. The selected heavy metals (Zn, Ni, Fe, and Cu) were found to be located in the perinuclear and cytoplasmic areas of A549 cells. The distribution pattern of metals from ambient particles showed that distributions of the metals in A549 cells were not uniform and followed the pattern Cu>Zn>Fe>Ni, suggesting that Cu was absorbed by A549 cells more easily than the other metals.

CONCLUSIONS

Metal nanoparticles oxides and UFPs at low concentration could damage to cells, but the manufactured metal oxide nanoparticles are not highly toxic to lung cells compared to environmental particles. The local concentration effect of heavy metals in A549 cells, as well as the induction of oxidative stress by the particles, may be responsible for the damage observed to the cells.

Aberrant cytokinesis and cell fusion result in multinucleation in HepG2 cells exposed to silica nanoparticles

The multinucleation effect of silica nanoparticles (SiNPs) had been determined in our previous studies, but the relative mechanisms of multinucleation and how the multinucleated cells are generated were still not clear. This extensional study was conducted to investigate the mechanisms underlying the formation of multinucleated cells after SiNPs exposure. We first investigated cellular multinucleation, then performed time-lapse confocal imaging to certify whether the multinucleated cells resulted from cell fusion or abnormal cell division. Our results confirmed for the first time that there are three patterns contributing to the SiNPs-induced multinucleation in HepG2 cells: cell fusion, karyokinesis without cytokinesis, and cytokinesis followed by fusion. The chromosomal passenger complex (CPC) deficiency and cell cycle arrest in G1/S and G2/M checkpoints may be responsible for the cell aberrant cytokinesis. The activated MAPK/ERK1/2 signaling and decreased mitosis related proteins might be the underlying mechanism of cell cycle arrest and thus multinucleation. In summary, we confirmed the hypothesis that aberrant cytokinesis and cell fusion resulted in multinucleation in HepG2 cells after SiNPs exposure. Since cell fusion and multinucleation were involved in genetic instability and tumor development, this study suggests the potential ability of SiNPs to induce cellular genetic instability. These findings raise concerns with regard to human health hazards and environmental risks with SiNPs exposure.

Cytotoxic and genotoxic evaluation of different synthetic amorphous silica nanomaterials in the V79 cell line

The nature of occupational risks and hazards in industries that produce or use synthetic amorphous silica (SAS) nanoparticles is still under discussion. Manufactured SAS occur in amorphous form and can be divided into two main types according to the production process, namely, pyrogenic silica (powder) and precipitated silica (powder, gel or colloid). The physical and chemical properties of SAS may vary in terms of particle size, surface area, agglomeration state or purity, and differences in their toxicity potential might therefore be expected. The aim of this study was to compare the cytotoxicity and genotoxicity of representative manufactured SAS samples in Chinese hamster lung fibroblasts (V79 cells). Five samples from industrial SAS producers were evaluated, that is, two pyrogenic SAS powders (with primary particle sizes of 20 nm and 25/70 nm), one precipitated SAS powder (20 nm) and two precipitated SAS colloids (15 and 40/80 nm). V79 cell cultures were treated with different concentrations of SAS pre-dispersed in bovine serum albumin -water medium. Pyr (pyrogenic) 20, Pre (precipitated) 20 and Col (colloid) 15 significantly decreased the cell viability after 24 h of exposure, whilst Pyr 25/70 and Col 40/80 had negligible effects. The cytotoxicity of Pyr 20, Pre 20 and Col 15 was revealed by the induction of apoptosis, and Pyr 20 and Col 15 also produced DNA damage. However, none of the SAS samples generated intracellular reactive oxidative species, micronuclei or genomic mutations in V79 cells after 24 h of exposure. Overall, the results of this study show that pyrogenic, precipitated and colloidal manufactured SAS of around 20 nm primary particle size can produce significant cytotoxic and genotoxic effects in V79 cells. In contrast, the coarser-grained pyrogenic and colloid SAS (approximately 50 nm) yielded negligible toxicity, despite having been manufactured by same processes as their finer-grained equivalents. To explain these differences, the influence of particle agglomeration and oxidative species formation is discussed.

Combined toxicity of amorphous silica nanoparticles and methylmercury to human lung epithelial cells

Exposure to the ambient particulate matters (PM) has been associated with the morbidity and mortality of cardiopulmonary diseases. Compared with coarse particles, ultrafine particles (UFP) absorb or condense higher concentration of toxic air pollutants and are easily inhaled into the lung. However, the combined effects of UFP and air pollutants on human health are still poorly understood. In this study, a co-exposure in vitro model of amorphous silica nanoparticles (nano-SiO2) and methyl mercury (MeHg) was established to investigate their combined effects and the potential joint action type. Lung adenocarcinoma cells (A549) were exposed to either nano-SiO2 or MeHg alone, or a combination of both. Factorial design was applied to analyze their potential joint action type. Higher interfacial energy was observed in the mixed solution of nano-SiO2 and MeHg. The intracellular content of both silicon and mercury in combination group were much higher than those in single exposure groups. In addition, the co-exposure of nano-SiO2 and MeHg enhanced the reactive oxygen species (ROS) generation, lipid peroxidation and reduced the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px). The excessive oxidative stress led to oxidative DNA damage as well as cellular apoptosis. Factorial design analysis demonstrated that additive and synergistic interactions were responsible for the combined toxicity of nano-SiO2 and MeHg.

Size-dependent toxicity and interactions of calcium oxalate dihydrate crystals on Vero renal epithelial cells

Urinary crystals in normal and kidney stone patients often have varying sizes; the interaction between renal epithelial cells and COD crystals generated in the tubular fluid could play an initiating role in the pathophysiology of calcium oxalate nephrolithiasis. This study aims to compare the cytotoxicity of micro/nano-calcium oxalate dihydrate (COD) crystals (50 nm, 100 nm, 600 nm, 3 μm, and 10 μm) toward African green monkey renal epithelial (Vero) cells to reveal the mechanism of kidney stone formation at the molecular and cellular levels.

METHODS

Vero cells were exposed to COD crystals of varying sizes at a concentration of 200 μg mL^-1 for 6 h. The effects of COD crystals on Vero cell viability, apoptosis rate, and cellular biochemical parameters [lactate dehydrogenase (LDH), superoxide dismutase (SOD), reactive oxygen species (ROS), hyaluronic acid (HA), osteopontin (OPN), and mitochondrial membrane potential (Δψ_m)] were determined using biochemical and morphological analyses.

RESULTS

Vero cell viability and apoptotic rate were closely associated with the size of COD crystals; lower cell viability and higher apoptosis rate were observed in cells exposed to smaller COD crystal size. The expression of SOD, ROS, HA and OPN also changed in a size-dependent manner after exposure to the five different sizes of COD crystals. The area ratio of the (100) face with a high density of Ca²⁺ ions to the total surface area was also found to influence the severity of cell injury. Cell injury induced by COD crystals was mainly caused by excessive expression of intracellular ROS and reduction of free-radical scavenger SOD. Moreover, binding of large crystals on the cell membrane surface takes more time to cause cell injury than internalized small-sized crystals. The cell death rate was found to be positively correlated with the amount of internalized COD crystals.

CONCLUSIONS

although the COD toxicity is often disregarded, the size-dependent cytotoxicity of COD crystals toward Vero cells is demonstrated in this study.

Mechanism of cytotoxicity of micron/nano calcium oxalate monohydrate and dihydrate crystals on renal epithelial cells

The toxicity difference and distribution in Vero cells of calcium oxalate with different crystal phases and sizes.

Ameliorative effect of Allolobophora caliginosa extract on hepatotoxicity induced by silicon dioxide nanoparticles

This study aims to evaluate the possible ameliorative effect of earthworm (Allolobophora caliginosa) extract (EE) against silicon dioxide nanoparticles (SiNPs)-induced liver injury in male albino rats. The effectiveness of EE was compared with silymarin as a standard hepatoprotective drug. The present work demonstrates the antioxidant activity of EE by 1,1-diphenyl-2-picrylhydrazyl assay. Administration of SiNPs, for 15 consecutive days, caused changes in most of the biochemical parameters, namely, serum aminotransferase enzymes activities (alanine transaminase and aspartate transaminase), alkaline phosphatase activity, total protein, total and direct bilirubin level, malondialdehyde, glutathione reduced, catalase, superoxide dismutase, glutathione reductase, and glutathione peroxidase. In addition, administration of SiNPs induced changes in liver tissue architecture. Administration of EE, for subsequent 30 days, to SiNPs exposure demonstrated significant ameliorative effects on nearly all the studied parameters, and such effects were compatible with those of silymarin. In addition, the administration of EE repairs, to some extent, the abnormal architecture of the liver tissue induced by SiNPs.

Optical imaging of absorption and distribution of RITC-SiO2 nanoparticles after oral administration

Purpose

In this study, we investigated the absorption and distribution of rhodamine B isothiocyanate (RITC)-incorporated silica oxide nanoparticles(SiNPs) (RITC-SiNPs) after oral exposure, by conducting optical imaging, with a focus on tracking the movement of RITC-SiNPs of different particle size and surface charge.

Methods

RITC-SiNPs (20 or 100 nm; positively or negatively charged) were used to avoid the dissociation of a fluorescent dye from nanoparticles via spontaneous or enzyme-catalyzed reactions in vivo. The changes in the nanoparticle sizes and shapes were investigated in an HCl solution for 6 hours. RITC-SiNPs were orally administered to healthy nude mice at a dose of 100 mg/kg. Optical imaging studies were performed at 2, 4, and 6 hours after oral administration. The mice were sacrificed at 2, 4, 6, and 10 hours post-administration, and ex vivo imaging studies were performed.

Results

The RITC-SiNPs were stable in the HCl solution for 6 hours, without dissociation of RITC from the nanoparticles and without changes in size and shape. RITC-SiNPs flowed into the small intestine from the stomach and gradually moved along the gut during the experiment. In the ex vivo imaging studies, optical signals were observed mostly in the lungs, liver, pancreas, and kidneys. The orally administered RITC-SiNPs, which were absorbed in the systemic circulation, were eliminated from the body into the urine. The 20 nm RITC-SiNPs showed higher uptake in the lungs than the 100 nm RITC-SiNPs. The distribution of the 100 nm RITC-SiNPs in the liver was higher than that of the 20 nm RITC-SiNPs, but the differences in the surface charge behavior were imperceptible.

Conclusion

We demonstrated that the movement of RITC-SiNPs after oral exposure could be traced by optical imaging. Optical imaging has the potential to provide valuable information that will help in understanding the behavior of SiNPs in the body following exposure.