[show abstract][hide abstract] ABSTRACT: One of the key challenges in the field of nanoparticle (NP) analysis is in producing reliable and reproducible characterisation data for nanomaterials. This study looks at the reproducibility using a relatively new, but rapidly adopted, technique, Nanoparticle Tracking Analysis (NTA) on a range of particle sizes and materials in several different media. It describes the protocol development and presents both the data and analysis of results obtained from 12 laboratories, mostly based in Europe, who are primarily QualityNano members. QualityNano is an EU FP7 funded Research Infrastructure that integrates 28 European analytical and experimental facilities in nanotechnology, medicine and natural sciences with the goal of developing and implementing best practice and quality in all aspects of nanosafety assessment. This study looks at both the development of the protocol and how this leads to highly reproducible results amongst participants. In this study, the parameter being measured is the modal particle size.
[show abstract][hide abstract] ABSTRACT: The release of reactive oxygen species (ROS) during the electron transport of mitochondrial aerobic respiration is the major source of ROS. However, contact between cells and nanoparticles (NPs) can also induce release of ROS, leading to an imbalance towards the pro-oxidative state. At low levels of ROS production, cells initiate a protective response to guarantee their survival, but an excess of ROS can damage cellular compounds such as membranes and various organelles, or directly cause genotoxicity. Thus an elevated level of ROS is an important indicator of cellular stress and an accurate recording of this parameter would be very informative. ROS can be measured by various assays, but all known assays measuring and quantifying ROS possess certain weaknesses. The problems and challenges of quantitatively detecting ROS in vitro using the 2',7'-dichlorodihydrofluorescein (DCF) assay is discussed as an example. In addition, we debate the difficulties in finding a suitable and stable chemical reaction control for the DCF assay (or other ROS-detecting assays). As a conclusion, we believe that using 3-morpholinosydnonimine hydrochloride (Sin-1) as a ROS inducer in the DCF assay is feasible only qualitatively. However, a quantitative measurement of the absolute amount of ROS produced and a quantitative comparison between experiments is (at the moment) impossible.
International journal of molecular sciences. 01/2013; 14(12):24320-37.
[show abstract][hide abstract] ABSTRACT: Microorganisms growing on painted surfaces are not only an aesthetic problem, but also actively contribute to the weathering and deterioration of materials. A widely used strategy to combat microbial colonization is the addition of biocides to the paint. However, ecotoxic, non-degradable biocides with a broad protection range are now prohibited in Europe, so the paint industry is considering engineered nanoparticles (ENPs) as an alternative biocide. There is concern that ENPs in paint might be released in run-off water and subsequently consumed by animals and/or humans, potentially coming into contact with cells of the gastrointestinal tract and affecting the immune system. Therefore, in the present study we evaluated the cytotoxic effects of three ENPs (nanosilver, nanotitanium dioxide and nanosilicon dioxide) that have a realistic potential for use in paints in the near future. When exposed to nanotitanium dioxide and nanosilicon dioxide in concentrations up to 243 µg/mL for 48 h, neither the gastrointestinal cells (CaCo-2) nor immune system cells (Jurkat) were significantly affected. However, when exposed to nanosilver, several cell parameters were affected, but far less than by silver ions used as a control. No differences in cytotoxicity were observed when cells were exposed to ENP-containing paint particles, compared with the same paint particles without ENPs. Paint particles containing ENPs did not affect cell morphology, the release of reactive oxygen species or cytokines, cell activity or cell death in a different manner to the same paint particles without ENPs. The results suggest that paints doped with ENPs do not pose an additional acute health hazard for humans.
[show abstract][hide abstract] ABSTRACT: Engineered nanomaterials, particularly carbon nanotubes (CNTs), hold great promise for a variety of industrial, consumer, and biomedical applications, due to their outstanding and novel properties. Over the last two decades many different types of CNTs have been produced at the industrial scale. Therefore, the exposure risk to humans associated with such a mass scale production has also increased substantially. This has led to increased concerns about the potential adverse health effects that may be associated with human exposure to CNTs, predominantly because of to their size, their shape, and chemistry. CNTs are also intended for use in many biomedical applications, and therefore their biocompatibility, biodistribution, and fate needs to be carefully assessed. This Minireview intends to highlight the current state of the assessment of potential adverse human health effects possibly associated with CNT exposure, as well as the challenges related to and posed by CNT safety research. The importance of reliability and comparison within and between different studies, as regards the test systems employed, is discussed as well as many other essential aspects relative to CNT safety research, for example efficient and comprehensive characterization, are discussed in the view of an improvement in data collection.
[show abstract][hide abstract] ABSTRACT: The amount of engineered nanomaterials (ENM) is constantly increasing. Their unique properties, compared to their bulk counterparts, render them suitable for various applications in many areas of life. Hence, nanomaterials appear in a variety of different consumer products leading to the exposure of human beings and the environment during their lifecycle. Even though results on biological effects of ENM are available, harmonized and validated test systems are still missing. One major problem concerning the reliable and robust toxicity testing arises from interactions of ENM with different assay systems. Modifications or damage to DNA can have fatal consequences, such as the formation of tumor cells and hence carcinogenesis. Therefore we focused on the re-evaluation of two genotoxicity assays concerning their nanomaterial compatibility; namely the cytokinesis-block micronucleus cytome assay (MN-assay) and the alkaline single cell gel electorphoresis assay (comet assay). We demonstrate the interference of ENM agglomerates with the read-out of both assays and discuss possibilities how to acquire relevant genotoxicity data.
Journal of Physics: Conference Series. 07/2011; 304(1):012053.
[show abstract][hide abstract] ABSTRACT: New properties of engineered nanomaterials raise great expectations for industrial, scientific as well as medical applications. At the same time concerns among consumers regarding the safety aspects of this new technology emerge. Furthermore, among the multitude of published studies, a considerable number do not reveal reliable data. Thus, standardized, validated, reliable, robust, reproducible and intelligent testing strategies are urgently needed that address nanomaterial toxicity. This article discusses the reliability of currently used in vitro toxicity assays. It covers major problems, pitfalls and challenges of assay performance and validation. We recommend a series of different controls to improve the experimental quality and, thus, also the reliability and reproducibility of current in vitro systems. These recommendations consequently applied in the future will increase the safe and sustainable use of nanotechnology.
[show abstract][hide abstract] ABSTRACT: Although nanotechnology is a relatively new scientific field, quite many different products are already introduced in the market containing nanosized particles. A special class of nanosized materials namely the carbon nanotubes (CNT) possesses outstanding new properties and extraordinary potential for creating new products. Carbon nanotubes are already used in various consumer products, industrial applications and science. It is not as this time clear how CNT are able to affect human health since most types of CNTs differ significantly in terms of structural characteristics (morphology, size, shape and length), surface properties (surface chemistry and surface charge) and chemical composition. This review provides an overview about contradicting reports that are found in the literature. We summarize the studies that report about nontoxic as well as toxic effects of CNT in-vitro and in-vivo. We describe how carbon nanotubes can readily be degraded under certain conditions. Another phenomenon is that despite the observed toxic effects which may occur to cells, organs and animals after uptake of CNT, intensive research investigations were undertaken in order to use these outstanding materials in medical applications. The second part of this review starts with a short description of the main principles in metrology. Observed conflicts were discussed in CNT toxicity assays into terms of measurement science or metrology issues. It was demonstrated that any specification of a measurand is only valid within the given framework. This means that many of the published results are within their measurement framework correct, but there are no means to compare them outside this framework.
Current medicinal chemistry. 01/2011; 18(14):2115-28.
[show abstract][hide abstract] ABSTRACT: The International Alliance for NanoEHS Harmonization (IANH) organises interlaboratory comparisons of methods used to study
the potential biological impacts of nanomaterials. The aim of IANH is to identify and reduce or remove sources of variability
and irreproducibility in existing protocols. Here, we present results of the first IANH round robin studies into methods to
assess the size and surface charge of suspended nanoparticles. The test materials used (suspensions of gold, silica, polystyrene,
and ceria nanoparticles, with [primary] particles sizes between 10nm and 80nm) were first analysed in repeatability conditions
to assess the possible contribution of between-sample heterogeneity to the between-laboratory variability. Reproducibility
of the selected methods was investigated in an interlaboratory comparison between ten different laboratories in the USA and
Europe. Robust statistical analysis was used to evaluate within- and between-laboratory variability. It is shown that, if
detailed shipping, measurement, and reporting protocols are followed, measurement of the hydrodynamic particle diameter of
nanoparticles in predispersed monomodal suspensions using the dynamic light scattering method is reproducible. On the other
hand, measurements of more polydisperse suspensions of nanoparticle aggregates or agglomerates were not reproducible between
laboratories. Ultrasonication, which is commonly used to prepare dispersions before cell exposures, was observed to further
increase variability. The variability of the zeta potential values, which were also measured, indicates the need to define
better surface charge test protocols and to identify sources of variability.
KeywordsNanoparticle–Particle surface charge–Interlaboratory comparison–Reproducibility–Polydispersity–Toxicology–Health and safety implications
Journal of Nanoparticle Research. 01/2011; 13(7):2675-2687.