Nano-TiO2 modulates the dermal sensitization potency of dinitrochlorobenzene after topical exposure

Little is known about the impact of engineered nanoparticles (ENPs) on the skin sensitization caused by chemicals.status: publishe

Toxicity of nanoparticles embedded in paints compared to pristine nanoparticles, in vitro study

The unique physicochemical properties of nanomaterials has led to an increased use in the paint and coating industry. In this study, the in vitro toxicity of three pristine ENPs (TiO2, Ag and SiO2), three aged paints containing ENPs (TiO2, Ag and SiO2) and control paints without ENPs were compared. In a first experiment, cytotoxicity was assessed using a biculture consisting of human bronchial epithelial (16HBE14o-) cells and human monocytic cells (THP-1) to determine subtoxic concentrations. In a second experiment, a new coculture model of the lung-blood barrier consisting of 16HBE14o- cells, THP-1 and human lung microvascular endothelial cells (HLMVEC) was used to study pulmonary and extrapulmonary toxicity. The results show that the pristine TiO2 and Ag ENPs have some cytotoxic effects at relative high dose, while pristine SiO2 ENPs and all aged paints with ENPs and control paints do not. In the complex triculture model of the lung-blood barrier, no considerable changes were observed after exposure to subtoxic concentration of the different pristine ENPs and paint particles. In conclusion, we demonstrated that although pristine ENPs show some toxic effects, no significant toxicological effects were observed when they were embedded in a complex paint matrix.publisher: Elsevier articletitle: Toxicity of nanoparticles embedded in paints compared to pristine nanoparticles, in vitro study journaltitle: Toxicology Letters articlelink: http://dx.doi.org/10.1016/j.toxlet.2014.11.030 content_type: article copyright: Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.status: publishe

Key Role of the Dispersion of carbon nanotubes (CNTs) within Epoxy Networks on their ability to Release

International audienceCarbon nanotubes (CNT) reinforced nanocomposites represent an unique opportunity in terms of designing advanced materials with mechanical reinforcement and electrical and thermal conductivities improvements. However, toxic effects of these composites on human health still have been studied and very soonly some regulations on CNT and on composites based on CNT will be enacted. That is why CNT releasing during nanocomposites lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNT and polymer compared to CNTs in a CNTs agglomerate, two dispersion states, one poorly dispersed versus another well dispersed are generated and finely described. So the main aim of this study is to check if CNT dispersion state has an influence on the CNT potential releasing in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, the electronic microscopies (SEM and TEM) but also the rheological analysis are carried out to well identify if CNTs are isolated, in bundles or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of good dispersion state, strong interfaces are generated linking the isolated nanotubes with the polymer whereas the CNT cohesion in an agglomerate seems much more weak and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites, i.e. CNTs poorly dispersed in the matrix are more readily released when compared to well dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations

Key Role of the Dispersion of carbon nanotubes (CNTs) within Epoxy Networks on their ability to Release

International audienceCarbon nanotubes (CNT) reinforced nanocomposites represent an unique opportunity in terms of designing advanced materials with mechanical reinforcement and electrical and thermal conductivities improvements. However, toxic effects of these composites on human health still have been studied and very soonly some regulations on CNT and on composites based on CNT will be enacted. That is why CNT releasing during nanocomposites lifecycle must be controlled. As the releasing depends on the interfacial strength that is stronger between CNT and polymer compared to CNTs in a CNTs agglomerate, two dispersion states, one poorly dispersed versus another well dispersed are generated and finely described. So the main aim of this study is to check if CNT dispersion state has an influence on the CNT potential releasing in the nanocomposite. To well tailor and characterize the CNT dispersion state in the polymer matrix, the electronic microscopies (SEM and TEM) but also the rheological analysis are carried out to well identify if CNTs are isolated, in bundles or in agglomerates. When the dispersion state is known and controlled, its influence on the polymerization kinetic and on mechanical properties is discussed. It appears clearly that in the case of good dispersion state, strong interfaces are generated linking the isolated nanotubes with the polymer whereas the CNT cohesion in an agglomerate seems much more weak and it does not provide any improvement to the polymer matrix. Raman spectroscopy is relevant to analyze the interfacial properties and allows the relationship with the releasing ability of nanocomposites, i.e. CNTs poorly dispersed in the matrix are more readily released when compared to well dispersed nanocomposites. The tribological tests confirm from released particles granulometry and observations that a CNT dispersion state sufficiently achieved in the nanocomposite avoids single CNT releasing under those solicitations

Toxicity of Nanoparticles Embedded in Paints Compared with Pristine Nanoparticles in Mice

The unique physical and chemical properties of nanomaterials have led to their increased use in many industrial applications, including as a paint additive. For example, titanium dioxide (TiO2) engineered nanoparticles (ENPs) have well-established anti-UV, self-cleaning, and air purification effects. Silver (Ag) ENPs are renowned for their anti-microbial capabilities and silicon dioxide (SiO2) ENPs are used as fire retardants and anti-scratch coatings. In this study, the toxic effects and biodistribution of three pristine ENPs (TiO2, Ag, and SiO2), three aged paints containing ENPs (TiO2, Ag, and SiO2) along with control paints without ENPs were compared. BALB/c mice were oropharyngeally aspirated with ENPs or paint particles (20 μg/aspiration) once a week for 5 weeks and sacrificed either 2 or 28 days post final aspiration treatment. A bronchoalveolar lavage was performed and systemic blood toxicity was evaluated to ascertain cell counts, induction of inflammatory cytokines, and key blood parameters. In addition, the lung, liver, kidney, spleen, and heart were harvested and metal concentrations were determined. Exposure to pristine ENPs caused subtle effects in the lungs and negligible alterations in the blood. The most pronounced toxic effects were observed after Ag ENPs exposure; an increased neutrophil count and a twofold increase in pro-inflammatory cytokine secretion (keratinocyte chemoattractant (KC) and interleukin-1ß (IL-1ß)) were identified. The paint containing TiO2 ENPs did not modify macrophage and neutrophil counts, but mildly induced KC and IL-1ß. The paints containing Ag or SiO2 did not show significant toxicity. Biodistribution experiments showed distribution of Ag and Si outside the lung after aspiration to respectively pristine Ag or SiO2 ENPs. In conclusion, we demonstrated that even though direct exposure to ENPs induced some toxic effects, once they were embedded in a complex paint matrix little to no adverse toxicological effects were identified.status: publishe

Contamination of nanoparticles by endotoxin: evaluation of different test methods

<p>Abstract</p> <p>Background</p> <p>Nanomaterials can be contaminated with endotoxin (lipopolysaccharides, LPS) during production or handling. In this study, we searched for a convenient <it>in vitro</it> method to evaluate endotoxin contamination in nanoparticle samples. We assessed the reliability of the commonly used limulus amebocyte lysate (LAL) assay and an alternative method based on toll-like receptor (TLR) 4 reporter cells when applied with particles (TiO₂, Ag, CaCO₃ and SiO₂), or after extraction of the endotoxin as described in the ISO norm 29701.</p> <p>Results</p> <p>Our results indicate that the gel clot LAL assay is easily disturbed in the presence of nanoparticles; and that the endotoxin extraction protocol is not suitable at high particle concentrations. The chromogenic-based LAL endotoxin detection systems (chromogenic LAL assay and Endosafe-PTS), and the TLR4 reporter cells were not significantly perturbed.</p> <p>Conclusion</p> <p>We demonstrated that nanoparticles can interfere with endotoxin detection systems indicating that a convenient test method must be chosen before assessing endotoxin contamination in nanoparticle samples.</p

Behavior of TiO₂ Released from Nano-TiO₂‑Containing Paint and Comparison to Pristine Nano-TiO₂

In the assessment of the fate and effects of engineered nanomaterials (ENM), the current focus is on studying the pristine, unaltered materials. However, ENM are incorporated into products and are released over the whole product life cycle, though mainly during the use and disposal phases. So far, released ENMs have only been characterized to a limited extent and almost nothing is known about the behavior of these materials under natural conditions. In this work we obtained material that was released from aged paint containing nano-TiO₂, characterized the particulate materials, and studied their colloidal stability in media with different pH and ionic composition. A stable suspension was obtained from aged paint powder by gentle shaking in water, producing a dilute suspension of 580 μg/L TiO₂ with an average particle size of 200–300 nm. Most particles in this suspension were small pieces of paint matrix that also contained nano-TiO₂. Some free nano-TiO₂ particles were observed by electron microscopy, but the majority was enclosed by the organic paint binder. The pristine nano-TiO₂ showed the expected colloidal behavior with increasing stability with increasing pH and strong agglomeration above the isoelectric point and settling in the presence of Ca. The released TiO₂ showed very small variations in particle size, ζ potential, and colloidal stability, even in the presence of 3 mM Ca. The results show that the behavior of released ENM may not necessarily be predicted by studying the pristine materials. Additionally, effect studies need to focus more on the particles that are actually released as we can expect that the toxic effect will also be markedly different between pristine and product released materials

Body distribution of SiO2-Fe3O4 core-shell nanoparticles after intravenous injection and intratracheal instillation

Nano-silicon dioxide (SiO2) is used nowadays in several biomedical applications such as drug delivery and cancer therapy, and is produced on an industrial scale as additive to paints and coatings, cosmetics and food. Data regarding the long-term biokinetics of SiO2 engineered nanoparticles (ENPs) is lacking. In this study, the whole-body biodistribution of SiO2 core-shell ENPs containing a paramagnetic core of Fe3O4 was investigated after a single exposure via intravenous injection or intratracheal instillation in mice. The distribution and accumulation in different organs was evaluated for a period of 84 days using several techniques, including magnetic resonance imaging, inductively coupled plasma mass spectrometry, X-ray fluorescence and X-ray absorption near edge structure spectroscopy. We demonstrated that intravenously administered SiO2 ENPs mainly accumulate in the liver, and are retained in this tissue for over 84 days. After intratracheal instillation, an almost complete particle clearance from the lung was seen after 84 days with distribution to spleen and kidney. Furthermore, we have strong evidence that the ENPs retain their original core-shell structure during the whole observation period. This work gives an insight into the whole-body biodistribution of SiO2 ENPs and will provide guidance for further toxicity studies.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=inan20status: publishe