Acute exposure to silica nanoparticles enhances mortality and increases lung permeability in a mouse model of Pseudomonas aeruginosa pneumonia

Background

The lung epithelium constitutes the first barrier against invading pathogens and also a major surface potentially exposed to nanoparticles. In order to ensure and preserve lung epithelial barrier function, the alveolar compartment possesses local defence mechanisms that are able to control bacterial infection. For instance, alveolar macrophages are professional phagocytic cells that engulf bacteria and environmental contaminants (including nanoparticles) and secrete pro-inflammatory cytokines to effectively eliminate the invading bacteria/contaminants. The consequences of nanoparticle exposure in the context of lung infection have not been studied in detail. Previous reports have shown that sequential lung exposure to nanoparticles and bacteria may impair bacterial clearance resulting in increased lung bacterial loads, associated with a reduction in the phagocytic capacity of alveolar macrophages.

Results

Here we have studied the consequences of SiO₂ nanoparticle exposure on Pseudomonas aeruginosa clearance, Pseudomonas aeruginosa-induced inflammation and lung injury in a mouse model of acute pneumonia. We observed that pre-exposure to SiO₂ nanoparticles increased mice susceptibility to lethal pneumonia but did not modify lung clearance of a bioluminescent Pseudomonas aeruginosa strain. Furthermore, internalisation of SiO₂ nanoparticles by primary alveolar macrophages did not reduce the capacity of the cells to clear Pseudomonas aeruginosa. In our murine model, SiO₂ nanoparticle pre-exposure preferentially enhanced Pseudomonas aeruginosa-induced lung permeability (the latter assessed by the measurement of alveolar albumin and IgM concentrations) rather than contributing to Pseudomonas aeruginosa-induced lung inflammation (as measured by leukocyte recruitment and cytokine concentration in the alveolar compartment).

Conclusions

We show that pre-exposure to SiO₂ nanoparticles increases mice susceptibility to lethal pneumonia but independently of macrophage phagocytic function. The deleterious effects of SiO₂ nanoparticle exposure during Pseudomonas aeruginosa-induced pneumonia are related to alterations of the alveolar-capillary barrier rather than to modulation of the inflammatory responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0078-9) contains supplementary material, which is available to authorized users.     

A dose-controlled system for air-liquid interface cell exposure and application to zinc oxide nanoparticles

Background  

Engineered nanoparticles are becoming increasingly ubiquitous and their toxicological effects on human health, as well as on the ecosystem, have become a concern. Since initial contact with nanoparticles occurs at the epithelium in the lungs (or skin, or eyes), in vitro cell studies with nanoparticles require dose-controlled systems for delivery of nanoparticles to epithelial cells cultured at the air-liquid interface.     

In vitro effects of nanoparticles on renal cells

Background  

The ability of nanoparticles to cross the lung-blood barrier suggests that they may translocate to blood and to targets distant from their portal of entry. Nevertheless, nanotoxicity in organs has received little attention. The purpose of this study was to evaluate nanotoxicity in renal cells using in vitro models. Various carbon black (CB) (FW2–13 nm, Printex60-21 nm and LB101-95 nm) and titanium dioxide (TiO₂-15 and TiO₂-50 nm) nanoparticles were characterized on size by electron microscopy. We evaluated theirs effects on glomerular mesangial (IP15) and epithelial proximal tubular (LLC-PK₁) renal cells, using light microscopy, WST-1 assay, immunofluorescence labeling and DCFH-DA for reactive oxygen species (ROS) assay.     

Chemically Modified (Nano)Silica as Sensitive Material for Arginine and Lysine

Abstract  

Silica has been derivatized with aminopropyl groups which subsequently have been chemically modified with N-methoxy-2,6-dinitroaniline derivatives to yield a solid which changes its color in the presence of arginine or lysine, from yellow to blue. Other amino-acids (such as glycine, valine, cysteine, cystine, alanine, phenylalanine, histidine) do not showed this behavior. The same procedure may be applied to silica nanoparticles. The new materials were characterized by UV–Vis, IR, and TEM.     

Enhanced CO2 separation performance of mixed matrix membrane by incorporating amine-functionalized silica filler

Mixed matrix membranes (MMMs) owing to the tunable characteristics and functionalization ability can effectively substitute the highly intensive conventional membranes for industrial-scale CO₂ separation. Further, to strengthen the interfacial polymer-filler interaction, an interfacial design strategy incorporating active functional groups in the filler surface can be demonstrated. In this study, as-synthesized silica nanoparticles (SNPs) was surface functionalized by (3-aminopropyl) trimethoxysilane silica modifier (AFSNP). The CO₂ separation of poly (vinyl alcohol)/polyethylene glycol based MMM infused with surface-functionalized SNP (AFSNP) was conducted. The comparative study highlighted in-depth analysis of intrinsic physicochemical properties of as-synthesized membranes and nanoparticles. Detailed characterization such as advanced microscopic analysis, X-ray photoelectron spectroscopy (XPS) analysis and ninhydrin assay validated the successful grafting of amino groups onto the silica surface. The morphological inspection corroborated the consistent dispersion ability of the nanoparticles in the membrane matrix. The effect of the operating conditions on the membrane selectivity and CO₂ permeance were statistically analyzed by ANOVA. The CO₂ permeation result (CO₂ permeance and CO₂/N₂ selectivity) exhibited many fold increment with surface functionalization of SNPs compared to undoped silica MMM. The defect-free, performance-oriented CO₂-selective membrane thus opened up the possibility of this combination as a prospective contender for large-scale carbon capture studies.     

Synthesis and Catalytic Properties of Carbon-Nanotube-Supported RuO<Subscript>2</Subscript> Catalyst Encapsulated in Silica Coating

Abstract  

A carbon-nanotube-supported RuO₂ nanocatalyst encapsulated in thin silica layer was successfully synthesized. The prior formation of silica over RuO₂ nanoparticles effectively hindered catalyst aggregation at high temperatures. The significant improvement of the resistance to sintering and the catalytic selectivity were demonstrated in competitive oxidation of n-butanol and i-butanol and methanol oxidative dehydrogenation.     

Controlled human wood smoke exposure: oxidative stress, inflammation and microvascular function

Background

Due to the rising use of nanomaterials (NMs), there is concern that NMs induce undesirable biological effects because of their unique physicochemical properties. Recently, we reported that amorphous silica nanoparticles (nSPs), which are one of the most widely used NMs, can penetrate the skin barrier and induce various biological effects, including an immune-modulating effect. Thus, it should be clarified whether nSPs can be a risk factor for the aggravation of skin immune diseases. Thus, in this study, we investigated the relationship between the size of SPs and adjuvant activity using a model for atopic dermatitis.

Results

We investigated the effects of nSPs on the AD induced by intradermaly injected-mite antigen Dermatophagoides pteronyssinus (Dp) in NC/Nga mice. Ear thickness measurements and histopathological analysis revealed that a combined injection of amorphous silica particles (SPs) and Dp induced aggravation of AD in an SP size-dependent manner compared to that of Dp alone. In particular, aggravation was observed remarkably in nSP-injected groups. Furthermore, these effects were correlated with the excessive induction of total IgE and a stronger systemic Th2 response. We demonstrated that these results are associated with the induction of IL-18 and thymic stromal lymphopoietin (TSLP) in the skin lesions.

Conclusions

A particle size reduction in silica particles enhanced IL-18 and TSLP production, which leads to systemic Th2 response and aggravation of AD-like skin lesions as induced by Dp antigen treatment. We believe that appropriate regulation of nanoparticle physicochemical properties, including sizes, is a critical determinant for the design of safer forms of NMs.     

Cu(II) ions removal from wastewater using starch nanoparticles (SNPs): An eco-sustainable approach

The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted by ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD) techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed by the XPS spectrum and energy-dispersive X-ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/ml dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m²/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo-second-order adsorption kinetics and follows the Langmuir isotherm. The R_L predicted by the Langmuir isotherm mechanism is 0.017, implying favourable adsorption. The process is reproducible and allows for the separation of heavy metal ions from the wastewater through biosorption effectively.     

A comparison of dispersing media for various engineered carbon nanoparticles

Background  

With the increased manufacture and use of carbon nanoparticles (CNP) there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others), and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes.     

Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach

The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.     

Genotoxic responses to titanium dioxide nanoparticles and fullerene in gpt delta transgenic MEF cells

Background  

Titanium dioxide (TiO₂) nanoparticles and fullerene (C₆₀) are two attractive manufactured nanoparticles with great promise in industrial and medical applications. However, little is known about the genotoxic response of TiO₂ nanoparticles and C₆₀ in mammalian cells. In the present study, we determined the mutation fractions induced by either TiO₂ nanoparticles or C₆₀ in gpt delta transgenic mouse primary embryo fibroblasts (MEF) and identified peroxynitrite anions (ONOO^-) as an essential mediator involved in such process.     

Biocompatible/bioabsorbable silver nanocomposite coatings

A novel biomass‐mediated method to synthesize cellulose‐stabilized silver nanoparticles (SNPs) and incorporate them into biocompatible/bioabsorbable poly‐L ‐lactic acid (PLLA) for producing SNP–PLLA nanocomposite thin films was developed and the antimicrobial efficacy and biocompatibility of the SNP–PLLA films were studied. The formation and coating morphology of SNPs were characterized with UV–visible spectrophotometry and transmission electron microscopy (TEM), and the release rate of silver ion from the SNP–PLLA films was determined by inductively coupled plasma‐optical emission spectrometry. Antimicrobial testing of the SNP–PLLA films performed with Staphylococcus aureus and Escherichia coli according to ISO 22196 standards demonstrated that the SNP–PLLA nanocomposite films with a SNP concentration of 700 ppm reduced colonies forming unit (CFU) counts by 99.8 and 99.99%, respectively. Despite the significant antimicrobial activity, the nanocomposite films with the same SNP concentration had little effect on the viability of human HeLa cells. This strategy that has been developed for the synthesis of nanoparticles and the formation of composite films demonstrates promise for reducing perioperative surgical site infections associated with indwelling devices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Gold nanoparticles induce cytotoxicity in the alveolar type-II cell lines A549 and NCIH441

Background  

During the last years engineered nanoparticles (NPs) have been extensively used in different technologies and consequently many questions have arisen about the risk and the impact on human health following exposure to nanoparticles. Nevertheless, at present knowledge about the cytotoxicity induced by NPs is still largely incomplete. In this context, we have investigated the cytotoxicity induced by gold nanoparticles (AuNPs), which differed in size and purification grade (presence or absence of sodium citrate residues on the particle surface) in vitro, in the human alveolar type-II (ATII)-like cell lines A549 and NCIH441.     

Synthesis of Nanorods with Ni Cores and Porous Silica Coatings

Abstract  

Nanorods with a Ni core and a silica coating have been prepared using a one-step synthesis and characterized using a variety of methods. Nitrogen adsorption isotherms have been used to characterize the pore size and the internal surface area of the silica shells grown on the Ni nanorods. Spectroscopic characterization of CO adsorbed on the Ni nanoparticle cores has been used to verify that the pore structure of the silica shells allows CO to access the Ni core; this property is critical to the use of core–shell structures as industrial catalysts. To demonstrate their resistance to physical and chemical degradation, the properties of the silica-coated Ni nanoparticles have been measured both before and after treatment at high temperature (623 - 1073 K) and exposure to a reducing atmosphere (hydrogen gas). Annealing at high temperatures reduces, but does not eliminate, the porosity of the silica shells.     

Characterizations of TiO2/SiO2/Ni–Cu–Zn Ferrite Composite for Magnetic Photocatalysts

The TiO₂/SiO₂/Ni–Cu–Zn ferrite composite for magnetic photocatalysts with high photocatalytic activity is successfully prepared in this study. The composite are composed of spherical or elliptical Ni–Cu–Zn ferrite nanoparticles about 20–60 nm as magnetic cores, silica as barrier layers with thickness of 15 nm between the magnetic cores and titania shells with thickness approximately 1.5 nm. Photodegradation examination of TiO₂/SiO₂/ Ni–Cu–Zn ferrite composite was carried out in methylene blue (MB) solutions illuminated under a Xe arc lamp with 35 W and color temperature of 6000 K. The results indicated that about 47.1% of MB molecules adsorbed on the TiO₂/SiO₂/Ni–Cu–Zn ferrite composite within 30 min mixing due to it higher pore volume of 0.034 cm³/g, and after 6 h Xe lamp irradiation, 83.9% of MB 16.1% was photodegraded. Compared with the TiO₂ /Ni–Cu–Zn ferrite composite, the TiO₂/SiO₂/Ni–Cu–Zn ferrite composite with silica barrier layer prohibited the photodissolution and enhanced the photocatalytic ability. The magnetic photocatalyst shows high photocatalytic efficiency that the apparent first‐order rate constant k_obs is 0.18427 h^?1, and good magnetic property that the saturation magnetization (M_s) of is 37.45 emu/g, suggesting the magnetic photocatalyst can be easily recovered by the application of an external magnetic field.     

Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?

Background  

Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties. Nevertheless, it was proven that, due to modest dispersion of nanoparticles, such high expectations often remain unmet. In this article, by introducing the notion of nanofin, a possible solution is envisioned, where nanostructures with high aspect-ratio are sparsely attached to a solid surface (to avoid a significant disturbance on the fluid dynamic structures), and act as efficient thermal bridges within the boundary layer. As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes.     

Hyperbranched Poly(Glycidol)-Grafted Silica Nanoparticles for Enhancing Li-Ion Conductivity of Poly(Ethylene Oxide)

Silica nanoparticles bearing hyperbranched polyglycidol (hbP) grafts are synthesized and blended with poly(ethylene oxide) (PEO) for the fabrication of composite solid polymer electrolytes (SPEs) for enhancing Li-ion conductivity. Different batches of hbPs are prepared, namely, the 5th, 6th, and 7th with increasing molecular weights using cationic ring-opening polymerization and grafted the hbPs onto the silica nanoparticles using quaternization reaction. The effect of end functionalization of hbP-grafted silica nanoparticles with a nitrile functional group (CN–hbP–SiO₂) on the ionic conductivity of the blends with PEO is further studied. High dipole moments indicate polar nature of nitriles and show high dielectric constants. Among all the hbPs, the 6th-batch CN–hbP–SiO₂ nanoparticles exhibit better ionic conductivity on blending with PEO showing ionic conductivity of 2.3 × 10⁻³ S cm⁻¹ at 80 °C. The blends show electrochemical stability up to 4.5 V versus lithium metal.     

PEG Modification Effect of Silica on the Suzuki–Miyaura Coupling Reaction Using Silica-immobilized Palladium Catalysts

Abstract  

The Pd phosphine complex catalysts immobilized onto polyethylene glycol (PEG)-modified silica were prepared in order to clarify the effect of the PEG modification on the Suzuki–Miyaura coupling reaction in organic solvents. For the reaction of ethyl p-bromobenzoate and phenylboronic acid in the presence of potassium carbonate in toluene, the PEG-modified silica-immobilized Pd catalysts exhibited much higher activities than the catalysts without PEG modification.     

Amorphous silica nanoparticles derived from biowaste via microwave combustion for drug delivery

Amorphous silica nanoparticles are a promising platform for constructing drug delivery vehicles owing to their high biocompatibility and favorable surface chemistry. In the current study, we report the preparation of amorphous silica nanoparticles using rice husk biowaste via easy and rapid microwave-assisted combustion. The obtained results from various characterizations indicate that the prepared sample is an amorphous form of silica nanoparticles having sizes 50–80 nm with high purity. Ciprofloxacin was used as the model drug and it was released from silica nanocarrier in a controlled and prolonged manner. The ciprofloxacin release kinetics was investigated using the Higuchi model and Ritger-Peppas model which corroborate that different process like desorption, diffusion, and surface erosion may be involved in the release of ciprofloxacin from the prepared silica nanocarrier. The antibacterial susceptibility test revealed that the ciprofloxacin loaded silica nanocarrier exhibit a bacterial inhibition zone about 32 ± 4 and 44 ± 3 mm against Escherichia coli and Staphylococcus aureus, respectively. This study can be useful to develop a versatile nanocarrier with controlled delivery of ciprofloxacin to treat different types of bacterial infections.     

NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript>@SiO<Subscript>2</Subscript> Nanoparticles Stabilized by Porous Silica Shells

Abstract  

NiFe₂O₄ nanoparticles stabilized by porous silica shells (NiFe₂O₄@SiO₂) were prepared using a one-pot synthesis and characterized for their physical and chemical stability in severe environments, representative of those encountered in industrial catalytic reactors. The SiO₂ shell is porous, allowing transport of gases to and from the metal core. The shell also stabilizes NiFe₂O₄ at the nanoparticle surface: NiFe₂O₄@SiO₂ annealed at temperatures through 973 K displays evidence of surface Ni, as verified by H₂ TPD analyses. At 1,173 K, hematite forms at the surface of the metallic cores of the NiFe₂O₄@SiO₂ nanoparticles and surface Ni is no longer observed. Without the silica shell, however, even mild reduction (at 773 K) can draw Fe to the surface and eliminate surface Ni sites.