New materials of emerging technological importance are single-walled carbon nanotubes (SWCNTs). Because SWCNTs will be used in commercial products in huge amounts, their effects on human health and the environment have been addressed in several studies. Inhalation studies in vivo and submerse applications in vitro have been described with diverging results. Why some indicate a strong cytotoxicity and some do not is what we report on here. Data from A549 cells incubated with carbon nanotubes fake a strong cytotoxic effect within the MTT assay after 24 h that reaches roughly 50%, whereas the same treatment with SWCNTs, but detection with WST-1, reveals no cytotoxicity. LDH, FACS-assisted mitochondrial membrane potential determination, and Annexin-V/PI staining also reveal no cytotocicity. SWCNTs appear to interact with some tetrazolium salts such as MTT but not with others (such as WST-1, INT, XTT). This interference does not seem to affect the enzymatic reaction but lies rather in the insoluble nature of MTT-formazan. Our findings strongly suggest verifying cytotoxicity data with at least two or more independent test systems for this new class of materials (nanomaterials). Moreover, we intensely recommend standardizing nanotoxicological assays with regard to the material used: there is a clear need for reference materials. MTT-formazan crystals formed in the MTT reaction are lumped with nanotubes and offer a potential mechanism to guide bioremediation and clearance for SWCNTs from "contaminated" tissue. SWCNTs are good supporting materials for tissue growth, as attachment of focal adhesions and connections to the cytoskeleton suggest.

Oops they did it again! Carbon nanotubes hoax scientists in viability assays.

Herein, an antibacterial system combining the “safe” carbon nanomaterials, graphene quantum dots (GQDs), with a low level of H2O2 has been put forward. It has been found that the peroxidase-like activity of GQDs originates from their ability to catalyze the decomposition of H2O2, generating ·OH. Since the ·OH has a higher antibacterial activity, the conversion of H2O2 into ·OH improves the antibacterial performance of H2O2, which makes it possible to avoid the toxicity of H2O2 at high levels in wound disinfection. All the experiments in vitro display that this intrinsic activity exerts a high enhancement of antibacterial activity of H2O2, and the designed system possessed broad spectrum of antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. More importantly, to assess the antibacterial efficacy of the designed system in actual wound disinfection, the GQD-Band-Aids are prepared and show excellent antibacterial property with the assistance...

Graphene quantum dots-band-aids used for wound disinfection.

Increasing evidence indicates that reactive oxygen species (ROS), consisting of superoxide, hydrogen peroxide, and multiple others, do not only cause oxidative stress, but rather may function as signaling molecules that promote health by preventing or delaying a number of chronic diseases, and ultimately extend lifespan. While high levels of ROS are generally accepted to cause cellular damage and to promote aging, low levels of these may rather improve systemic defense mechanisms by inducing an adaptive response. This concept has been named mitochondrial hormesis or mitohormesis. We here evaluate and summarize more than 500 publications from current literature regarding such ROS-mediated low-dose signaling events, including calorie restriction, hypoxia, temperature stress, and physical activity, as well as signaling events downstream of insulin/IGF-1 receptors, AMP-dependent kinase (AMPK), target-of-rapamycin (TOR), and lastly sirtuins to culminate in control of proteostasis, unfolded protein response (UPR), stem cell maintenance and stress resistance. Additionally, consequences of interfering with such ROS signals by pharmacological or natural compounds are being discussed, concluding that particularly antioxidants are useless or even harmful.

/pdf/mitohormesis-promoting-health-and-lifespan-by-increased-2ww3vz7l3b.pdf

Mitohormesis: Promoting Health and Lifespan by Increased Levels of Reactive Oxygen Species (ROS).

Biodistribution of PEG-modified gold nanoparticles following intratracheal instillation and intravenous injection

The rapidly increasing production of engineered nanoparticles has created a demand for particle removal from industrial and communal wastewater streams. Efficient removal is particularly important in view of increasing long-term persistence and evidence for considerable ecotoxicity of specific nanoparticles. The present work investigates the use of a model wastewater treatment plant for removal of oxide nanoparticles. While a majority of the nanoparticles could be captured through adhesion to clearing sludge, a significant fraction of the engineered nanoparticles escaped the wastewater plant's clearing system, and up to 6 wt % of the model compound cerium oxide was found in the exit stream of the model plant. Our study demonstrates a significant influence of surface charge and the addition of dispersion stabilizing surfactants as routinely used in the preparation of nanoparticle derived products. A detailed investigation on the agglomeration of oxide nanoparticles in wastewater streams revealed a high stabilization of the particles against clearance (adsorption on the bacteria from the sludge). This unexpected finding suggests a need to investigate nanoparticle clearance in more detail and demonstrates the complex interactions between dissolved species and the nanoparticles within the continuously changing environment of the clearing sludge.

/pdf/removal-of-oxide-nanoparticles-in-a-model-wastewater-22eld58smo.pdf

Removal of oxide nanoparticles in a model wastewater treatment plant: influence of agglomeration and surfactants on clearing efficiency.

Metal oxides may hold, as nanosized particles, a toxic potential to human health and the environment that is not present in the bulk material. Due to the high surface-to-volume ratio, small amounts can lead to strong oxidative damage within biological systems, impairing cellular functions as a consequence of their high surface reactivity. We report here on a new nanosized V2O3 material that has a needle-like structure with diameters of less than 30 nm and variable lengths. The potentiated toxicity of nanoscale vanadium oxide (V2O3) compared to bulk material is demonstrated here in human endo- and epithelial lung cells, and might be due to the higher catalytic surface of the particles. Reduction in cell viability is almost ten times stronger and starts with lowest concentrations of “nanoscaled” material (10 μg/mL). Vanadium oxide leads to an induction of heme oxygenase 1 (HO-1) in a dose dependent manner in ECV304 cells whereas a reduction in protein levels can be observed for the epithelial cells (A549). ...

Nanoparticulate Vanadium Oxide Potentiated Vanadium Toxicity in Human Lung Cells

The sections in this article are


Introduction
Nanoscale Materials and Adverse Health Effects: Precautionary Measures
Hazard Identification and Exposure Estimation


Production and Use of “New Carbon Modifications” and Metal Oxides
Health Aspects
Uptake and Possible Transport, Depots, and Accumulation in Living Organisms
Biological Effects on Cellular Mechanisms
Metal Oxides
New Carbon Modifications


Possible Hazards – Toxicological Impacts


Risk Characterization – A Conclusion
Opportunities and Risks of Nanomaterials
New Materials without Risks?

Toxicity of Nanomaterials – New Carbon Conformations and Metal Oxides

Human lung epithelial cells show biphasic oxidative burst after single-walled carbon nanotube contact

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Nanoparticulate Vanadium Oxide Potentiated Vanadium Toxicity in Human Lung Cells

Toxicity of Nanomaterials – New Carbon Conformations and Metal Oxides

Human lung epithelial cells show biphasic oxidative burst after single-walled carbon nanotube contact