Multi-walled Carbon Nanotubes, NM-400, NM-401, NM-402, NM-403: Characterisation and Physico-Chemical Properties

In 2011 the JRC launched a Repository for Representative Test Materials that supports both EU and international research projects, and especially the OECD Working Party on Manufactured Nanomaterials' (WPMN) exploratory testing programme "Testing a Representative set of Manufactured Nanomaterials" for the development and collection of data on characterisation, toxicological and ecotoxicological properties, as well as risk assessment and safety evaluation of nanomaterials. The JRC Repository responds to a need for availability of nanomaterial from a single production batch to enhance the comparability of results between different research laboratories and projects. The present report presents the physico-chemical characterisation of the multi-walled carbon nanotubes (MWCNT) from the JRC Repository: NM-400, NM-401, NM-402 and NM-403. NM-400 was selected as principal material for the OECD WPMN testing programme. They are produced by catalytic chemical vapour deposition. Each of these NMs originates from one respective batch of commercially manufactured MWCNT. They are nanostructured, i.e. they consist of more than one graphene layer stacked on each other and rolled together as concentric tubes. The MWCNT NMs may be used as a representative material in the measurement and testing with regard to hazard identification, risk and exposure assessment studies. The results are based on studies by several European laboratories participating to the NANOGENOTOX Joint Action.JRC.I.4-Nanobioscience

Titanium Dioxide, NM-100, NM-101, NM-102, NM-103, NM-104, NM-105: Characterisation and Physico-Chemical Properties

The European Commission's Joint Research Centre (JRC) provides scientific support to European Union policy including nanotechnology. Within this context, the JRC launched, in February 2011, a repository for Representative Test Materials (RTMs), based on preparatory work started in 2008. It supports both EU and international research projects, and especially the OECD Working Party on Manufactured Nanomaterials (WPMN). The WPMN leads an exploratory testing programme "Testing a Representative set of Manufactured Nanomaterials" for the development and collection of data on characterisation, toxicological and ecotoxicological properties, as well as risk assessment and safety evaluation of nanomaterials. The purpose is to understand the applicability of the OECD Test Guidelines for the testing of nanomaterials as well as end-points relevant for such materials. The Repository responds to a need for nanosafety research purposes: availability of nanomaterial from a single production batch to enhance the comparability of results between different research laboratories and projects. The availability of representative nanomaterials to the international scientific community furthermore enhances and enables development of safe materials and products. The present report presents the physico-chemical characterisation of the Titanium dioxide series from the JRC repository: NM-100, NM-101, NM-102, NM-103, NM-104 and NM-105. NM-105 was selected as principal material for the OECD test programme "Testing a representative set of manufactured nanomaterials". NM-100 is included in the series as a bulk comparator. Each of these NMs originates from one batch of commercially manufactured TiO2. The TiO2 NMs may be used as representative material in the measurement and testing with regard to hazard identification, risk and exposure assessment studies. The results for more than 15 endpoints are addressed in the present report, including physico-chemical properties, such as size and size distribution, crystallite size and electron microscopy images. Sample and test item preparation procedures are addressed. The results are based on studies by several European laboratories participating to the NANOGENOTOX Joint Action, as well as by the JRC.JRC.I.4-Nanobioscience

Chemical analysis of thin films in electronic devices by analytical transmission electron microscopy methodologies

The continuous scaling in semiconductor technology has made characterization of transistor components more challenging. One of the main difficulties is to combine high spatial resolution with high enough sensitivity to perform accurate and precise quantitative analysis. In this project, methodologies for the characterization of thin films in electronic devices are developed, based on analytical transmission electron microscopy (TEM) techniques such as energy dispersive X-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The problems which are addressed are the quantification methods and their accuracy, the artifacts induced by specimen preparation, and the combination of quantification and spatial resolution. In the first part of the project, quantification methodologies are developed by studying a series of nickel silicide phases with different crystallographic structures and compositions. The methodologies are generic enough to characterize other materials as well. The analyses are performed in STEM mode where a nanometer sized electron probe is directed onto the specimen. To separate the quantification problem from the spatial resolution problem, the quantification methodologies are developed on specimens with a nickel silicide layer thickness of about 100 nm. The influence of the specimen thickness on the quantification results is investigated by studying wedge shaped specimens. In the second part of the project, artifacts induced by the specimen preparation method are examined on the different nickel silicide phases. Focused ion beam (FIB) is commonly used for preparation of TEM specimens of devices, but induces a damaged layer in the specimen during the milling procedure. The formation of surface damage and the difference in milling rate between the silicide layer and the silicon substrate are studied as a function of the silicide phase. It is demonstrated that sample preparation with FIB influences both the quantification accuracy and spatial resolution that can be obtained. Methodologies to reduce damage induced by the milling procedure are investigated. In the third part of the project, the developed methodologies are validated on thin film specimens, where spatial resolution becomes important. The obtainable spatial resolution is examined by performing line scan experiments over a sharp interface. The combination of quantification and spatial resolution is then explored by a few case studies. These case studies allow evaluating the advantages and limitations of the quantitative methodologies. In addition, it is examined if the signals obtained from the different techniques can be combined into a single experiment. The methodologies are compared on the basis of spatial resolution versus analytical sensitivity, quantification accuracy and precision, specimen requirements, ease of use and information content.status: publishe

Measurement uncertainties of size, shape, and surface measurements using transmission electron microscopy of near-monodisperse, near-spherical nanoparticles

Transmission electron microscopy (TEM) in combination with systematic random imaging, semi-automatic image analysis and data processing has been validated for size, shape and surface topology measurements of silica nanoparticles. The accuracy of the validated TEM method was assessed by measuring two selected colloidal silica certified reference materials, ERM-FD100 and ERM-FD304. The measurement uncertainties were estimated for the modal and median particle size, shape and surface topology parameters of single primary particles. The single primary particles are distinguished from agglomerates using a linear discriminant analysis approach. After optimization of the binning process, the mode associated to the number-based particle size distribution was obtained by lognormal fitting. The methodology described in this paper, where a high level of automation of calibration, image acquisition, image analysis and data analysis is obtained, gives robust results for the modal area equivalent circular particle diameter (ECD). The expanded uncertainty of the modal ECD is estimated to be about 3 %. The largest contribution to the expanded uncertainty was found to stem from the uncertainty associated to the trueness of the TEM method.  JRC.D.2-Standards for Innovation and sustainable Developmen

Quantitative characterization of agglomerates and aggregates of pyrogenic and precipitated amorphous silica nanomaterials by transmission electron microscopy

<p>Abstract</p> <p>Background</p> <p>The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM.</p> <p>Results</p> <p>Bright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose.</p> <p>Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM.</p> <p>Conclusion</p> <p>The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor.</p

Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials

An approach for the size measurement of particulate (nano)materials by transmission electron microscopy was evaluated. The approach combines standard operating procedures for specimen preparation, imaging, and image analysis, and it was evaluated on a series of certified reference materials and representative test materials with varying physical properties, including particle size, shape, and agglomeration state. The measurement of the median value of the minimal external particle diameter distribution was intra-laboratory validated. The validation study included an assessment of the limit of detection, working range, selectivity, precision, trueness, robustness, and ruggedness. An uncertainty that was associated to intermediate precision in the range of 1–7% and an expanded measurement uncertainty in the range of 7–20% were obtained, depending on the material and image analysis mode. No bias was observed when assessing the trueness of the approach on the certified reference materials ERM-FD100 and ERM-FD304. The image analysis method was validated in an inter-laboratory study by 19 laboratories, which resulted in a within-laboratory precision in the range of 2–8% and a between-laboratory precision of between 2% and 14%. The automation and standardization of the proposed approach significantly improves labour and cost eciency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.JRC.F.6-Reference Material

Increased surface area of halloysite nanotubes due to surface modification predicts lung inflammation and acute phase response after pulmonary exposure in mice

The toxicological potential of halloysite nanotubes (HNTs) and variants after functional alterations to surface area are not clear. We assessed the toxicological response to HNTs (NaturalNano (NN)) before and after surface etching (NN-etched). Potential cytotoxicity of the two HNTs was screened&nbsp;in vitro&nbsp;in MutaTMMouse lung epithelial cells. Lung inflammation, acute phase response and genotoxicity were assessed 1, 3, and 28 days after a single intratracheal instillation of adult female C57BL/6 J BomTac mice. The doses were 6, 18 or 54 μg of HNTs, compared to vehicle controls and the Carbon black NP (Printex 90) of 162 μg/mouse. The cellular composition of bronchoalveolar lavage (BAL) fluid was determined as a measure of lung inflammation. The pulmonary and hepatic acute phase responses were assessed by&nbsp;Serumamyloida&nbsp;mRNA levels in lung and liver tissue by real-time quantitative PCR. Pulmonary and systemic genotoxicity were analyzed by the alkaline comet assay as DNA strand breaks in BAL cells, lung and liver tissue. The etched HNT (NN-etched) had 4–5 times larger BET surface area than the unmodified HNT (NN). Instillation of NN-etched at the highest dose induced influx of neutrophils into the lungs at all time points and increased&nbsp;Saa3&nbsp;mRNA levels in lung tissue on day 1 and 3 after exposure. No genotoxicity was observed at any time point. In conclusion, functionalization by etching increased BET surface area of the studied NN and enhanced pulmonary inflammatory toxicity in&nbsp;mice.</p