TY - JOUR T1 - The use of nitrous oxide whippets as a recreational drug: Hidden health risks. JF - Drug Test Anal Y1 - 2024 A1 - Bart Desmedt A1 - Eveline Verleysen A1 - Heidi Demaegdt A1 - Peter van Campenhout A1 - Erik van Miert A1 - Eric Deconinck KW - N2O; drug abuse; illegal drugs; nanoparticles; zinc oxide. AB -

Whipped cream canisters, also known as nitrous oxide whippets, are traditionally used in the culinary arts to prepare food foams. In recent years, however, these gas canisters have been cracked open and inhaled to produce a "legal" high. Users of these whippets have reported the presence of an oily residue containing metallic particles. This contamination was investigated using liquid chromatography-, gas chromatography- and inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). The particulate matter was also analyzed by scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDX). The presence of cyclohexyl isothiocyanate was confirmed at a maximum concentration of 67 μg per whippet. ICP-MS and ICP-OES analysis revealed the presence of mainly iron and zinc, but also, traces of aluminum, chromium, cobalt, nickel, and lead were found. STEM-EDX analysis confirmed the presence of nano-sized particles containing iron and zinc. When simulating inhalation, using the multiple path particle dosimetry model, it was confirmed that these nano-sized particles can reach the deeper parts of the lungs. Most users assume that inhaling a food-grade nitrous oxide whippet for a "legal" high poses no risks. However, this research shows that users are exposed to cyclohexyl isothiocyanate, a substance classified as a respiratory sensitizer. The presence of zinc in the particulate matter could potentially be linked to lung lesions.

CP - 16 M3 - 10.1002/dta.3518 ER - TY - JOUR T1 - Application of silver-based biocides in face masks intended for general use requires regulatory control JF - Science of The Total Environment Y1 - 2023 A1 - Jan Mast A1 - Erik Van Miert A1 - Lisa Siciliani A1 - Karlien Cheyns A1 - Marie-Noelle Blaude A1 - Charlotte Wouters A1 - Nadia Waegeneers A1 - Ruud Bernsen A1 - Christiane Vleminckx A1 - Joris Van Loco A1 - Eveline Verleysen KW - Ag KW - Biocide KW - electron microscopy KW - Face masks KW - ICPMS KW - Nanoparticle KW - Physicochemical characterization KW - Risk Assessment KW - Silver KW - textile AB -

Silver-based biocides are applied in face masks because of their antimicrobial properties. The added value of biocidal silver treatment of face masks to control SARS-CoV-2 infection needs to be balanced against possible toxicity due to inhalation exposure. Direct measurement of silver (particle) release to estimate exposure is problematic. Therefore, this study optimized methodologies to characterize silver-based biocides directly in the face masks, by measuring their total silver content using ICP-MS and ICP-OES based methods, and by visualizing the type(s) and localization of silver-based biocides using electron microscopy based methods. Thirteen of 20 selected masks intended for general use contained detectable amounts of silver ranging from 3 μg to 235 mg. Four of these masks contained silver nanoparticles, of which one mask was silver coated. Comparison of the silver content with limit values derived from existing inhalation exposure limits for both silver ions and silver nanoparticles allowed to differentiate safe face masks from face masks that require a more extensive safety assessment. These findings urge for in depth characterization of the applications of silver-based biocides and for the implementation of regulatory standards, quality control and product development based on the safe-by-design principle for nanotechnology applications in face masks in general.

VL - 870 M3 - 10.1016/j.scitotenv.2023.161889 ER - TY - Generic T1 - Application of silver-based biocides in face masks intended for general use requires regulatory control Y1 - 2023 A1 - Jan Mast A1 - Erik Van Miert A1 - Lisa Siciliani A1 - Karlien Cheyns A1 - Charlotte Wouters A1 - Nadia Waegeneers A1 - Ruud Bernsen A1 - Christiane Vleminckx A1 - Joris Van Loco A1 - Eveline Verleysen ER - TY - Generic T1 - Characterisation of iron oxides and hydroxides applied in the food chain by electron microscopy Y1 - 2023 A1 - Lisa Siciliani A1 - Eveline Verleysen A1 - Sara Bals A1 - Fanny Caputo A1 - Jan Mast KW - E 172 KW - Iron oxide KW - Nanoparticles JF - The 20th International Microscopy Congress (IMC20) CY - Busan, South Korea ER - TY - Generic T1 - Characterisation of nanocellulose applied in the food chain by electron microscopy Y1 - 2023 A1 - Lisa Siciliani A1 - Eveline Verleysen A1 - Sara Bals A1 - Francesco Fumagalli A1 - Francesco Cubadda A1 - Jan Mast KW - NAMs KW - nanocellulose KW - nanospecific assessment JF - The 20th International Microscopy Congress (IMC20) CY - Busan, South Korea ER - TY - RPRT T1 - EFSA Project on the use of New Approach Methodologies (NAMs) for the hazard assessment of nanofibres. Lot 1, nanocellulose oral exposure: gastrointestinal digestion, nanofibres uptake and local effects Y1 - 2023 A1 - Olimpia Vincentini A1 - Anne‐Louise Blier A1 - Alessia Bogni A1 - Morgane Brun A1 - Serena Cecchetti A1 - Francesca De Battistis A1 - Sylvain Denis A1 - Lucie Etienne‐Mesmin A1 - Francesca Ferraris A1 - Francesco Sirio Fumagalli A1 - Kevin Hogeveen A1 - Francesca Iacoponi A1 - Andrea Raggi A1 - Lisa Siciliani A1 - Stanco, Deborah A1 - Eveline Verleysen A1 - Valerie Fessard A1 - Jan Mast A1 - Stephanie Blanquet‐Diot A1 - Susanne Bremer‐Hoffmann A1 - Francesco Cubadda KW - barrier crossing KW - cell uptake KW - hazard identification KW - IATAs KW - NAMs KW - nanocellulose KW - nanospecific assessment AB -

Nanocellulose (NC) is an emerging material in the food sector with several prospective application areas. Three main types of NC exist, i.e. bacterial NC (BNC), nanofibrillated cellulose (NFC), and cellulose nanocrystals (CNC). The biological sources and processing conditions affect several physicochemical parameters of NC. In the present project, a NAM-based IATA for addressing data gaps in the assessment of potential hazards associated to NC oral exposure was considered. This IATA focused on three main pillars, i.e. (i) assessment of the uptake and potential crossing of the intestinal barrier by NC, (ii) assessment of local effects, including inflammation and genotoxicity, on the gastrointestinal epithelia, and (iii) assessment of any digestion or degradation of NC by the human microbiome. Eight NC samples belonging to the three NC types, plus a comparator in the micro-range, were selected as study materials and submitted to a thorough physicochemical characterisation. A battery of in vitro tests was used to provide insight into NC hazard and mode of action according to a tiered approach, which lead to selection of three materials belonging to the three main NC types for in depth-testing. Cell uptake of these materials was demonstrated, and such uptake was greater in a triculture model, which better simulates the barrier properties of the human intestinal epithelium, as compared to Caco-2 monolayers. Uptake was the greatest in repeated exposure conditions, in which intestinal barrier crossing was demonstrated for CNC. Pro-inflammatory responses accompanied by massive NC uptake in macrophages, indicative for potential immunotoxicological effects, and barrier function impairment were observed, whereas no indications for genotoxicity were obtained. Finally, no formation of smaller particles following colonic fermentation of NC was observed. For the integration of these results in regulatory hazard assessment of NC after oral exposure, prospective use of NC as novel food or as food additive was considered.

JF - EFSA Supporting Publications VL - 20 CP - 9 M3 - 10.2903/sp.efsa.2023.EN-8258 ER - TY - Generic T1 - Identification and characterization of inorganic food additives and pearlescent pigments in sprays for food decoration by STEM-EDX Y1 - 2023 A1 - Noa Olluyn A1 - Eveline Verleysen A1 - Lisa Siciliani A1 - Daniel Arenas Esteban A1 - S. Mathioudaki A1 - Sara Bals A1 - Subhalakshmi Sharma A1 - Jan Mast A1 - Joris Van Loco KW - electron microscopy KW - inorganic food additives KW - pearlescent pigments KW - sprays KW - STEM-EDX AB -

Food colorants are applied in commercial products and domestic cooking to enhance the appearance of food. To obtain specific hues, inorganic food additives containing (nano)particles are mixed in varying concentrations, and pearlescent pigments consisting of mica platelets coated with a layer of titanium dioxide and/or iron oxide particles, are applied to provide glitter effects1. For control and risk assessment of multi-constituent substances and mixtures, characterisation of the fraction of small particles, including the particle size distribution, is needed for each single constituent or each component in the mixture2. This is challenging for control laboratories and only limited guidance is currently available3.
This study developed electron microscopy-based methods to identify and characterize the particles of individual components in eight commercially available food-decoration sprays of different colours, containing mixtures of food additives and pearlescent pigments. No dispersion protocols or purifications steps were applied to optimally assess the properties of the particles consumers are exposed to. Samples were prepared by spraying 5mL in a glass vial and coated on EM-grids using the grid-on-drop method. Scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDX) allowed identifying particles of separate components, including potassium aluminium silicate-based pearlescent pigments, vegetable carbon, rutile titanium dioxide (nano)particles, iron oxide (nano)particles and aluminium containing (nano)particles by their elemental composition. Their presence and relative concentration varied between spray colours. Often the layer of titanium dioxide particles detached from the mica, and titanium dioxide particles were also observed forming near-spherical aggregates. STEM-EDX tomography allowed identifying particles of overlapping components and examining the structure of the pearlescent pigments in 3D. The presence of a fraction of nanoparticles in each component was demonstrated based on their particle size distributions. The methods and findings support regulatory bodies to assess and control possible health risks of mixtures of (nano)particles present in the food chain.

JF - IMEKOFOODS 2023 PB - Imekofoods CY - Paris ER - TY - RPRT T1 - Silver-based biocides and titanium dioxide particles in face masks for general use. Final report of the TiO2Mask and AgMask COVID-19 projects. Y1 - 2023 A1 - Daniela Montalvo A1 - Charlotte Wouters A1 - Lisa Siciliani A1 - Christiane Vleminckx A1 - Erik Van Miert A1 - Nadia Waegeneers A1 - Joris Van Loco A1 - Eveline Verleysen A1 - Karlien Cheyns A1 - Jan Mast KW - Face masks KW - Nanoparticles KW - silver-based biocides KW - titanium dioxide PB - Sciensano CY - Brussels, Belgium ER - TY - JOUR T1 - Determination of the Transport Efficiency in spICP-MS Analysis Using Conventional Sample Introduction Systems: An Interlaboratory Comparison Study JF - Nanomaterials Y1 - 2022 A1 - Otmar Geiss A1 - Ivana Bianchi A1 - Guillaume Bucher A1 - Eveline Verleysen A1 - Frederic Brassinne A1 - Jan Mast A1 - Katrin Loeschner A1 - Lucas Givelet A1 - Francesco Cubadda A1 - Francesca Ferraris A1 - Andrea Raggi A1 - Francesca Iacoponi A1 - Peters, Ruud J B A1 - Anna Undas A1 - Alexandra Müller A1 - Ann-Katrin Meinhardt A1 - Birgit Hetzer A1 - Volker Gräf A1 - Antonio R. Montoro Bustos A1 - Josefa Barrero-Moreno VL - 12 CP - 4 M3 - 10.3390/nano12040725 ER - TY - RPRT T1 - Evaluation of the types, efficient use and health risks of application of silver-based biocides to provide antimicrobial properties to face masks applied during the Covid-19 crisis Y1 - 2022 A1 - Jan Mast A1 - Marie-Noelle Blaude A1 - Lisa Siciliani A1 - Karlien Cheyns A1 - Nadia Waegeneers A1 - Christiane Vleminckx A1 - Joris Van Loco A1 - Eveline Verleysen KW - biocides KW - Face masks KW - Ions KW - Nanoparticles KW - Silver AB -

In situ analysis of silver based biocides in face masks using electron microscopy and EDX, combined with total silver measurement using ICP-MS or ICP-OES demonstrated the presence of varying amounts and different types of silver-based biocides in a selection of face masks on the Belgian market and intended to be worn by the general public. Following types of silver-based biocides were demonstrated: (i) Ag+ ions, (ii) metallic Ag0 NP distributed in the matrix of the fibers, (iii) Ag NP and large silver particles at the surface of, or close to cotton fibres in face masks containing polycationic polymers binding Ag+ ions, and (iv) a coating consisting of metallic silver releasing Ag+ ions, Ag0 NP and large silver particles.

For metallic and ionic silver, an acceptable exposure level (AELmask) of 25 µg per mask was established based on occupational exposure levels and assuming an intensive exposure scenario considering subchronic exposure of the general adult population.

Comparison of the measured amount of total silver in the masks with this AELmask indicated that seven out of nine face masks, with a silver biocide based on Ag+ ions only, can be considered as safe. The two other face masks with a silver biocide based on Ag+ ions require a more refined risk evaluation.

The amount of silver in the four masks that contain Ag0 NP, Ag+ ions, and/or non-nanoparticulate silver exceeded the AELmask. Per case an in depth risk analysis needs to be undertaken to account for the different forms of silver that are potentially released from face masks treated with the applied silver-based biocides.

CY - Brussels, Belgium ER - TY - Generic T1 - Identification and characterization of TiO2 nanoparticles in face masks by TEM Y1 - 2022 A1 - Charlotte Wouters A1 - Lisa Siciliani A1 - Marina Ledecq A1 - Eveline Verleysen A1 - Jan Mast KW - Agglomerates KW - electron microscopy KW - energy dispersive X-ray spectroscopy KW - Face mask KW - image analysis KW - Nanoparticles KW - particle size distribution KW - STEMEDX KW - TEM KW - textile KW - ultramicrotomy AB -

Because of the possible health risks related to the use of nanoparticle technologies in face masks, a general methodology is developed for identification, localization and particle size measurement of nanoparticles in situ in face masks by conventional and analytical transmission electron microscopy (TEM). The methodology can be applied by following this protocol which includes (i) preparation of resin-embedded ultra-thin sections of face masks suitable for TEM analysis, a procedure that can be applied to any type of textile, (ii) visualization and identification of the (nano)particles inside the cross section of the textile fibres by scanning TEM (STEM) combined with energy dispersive X-ray spectroscopy (EDX), (iii) measurement of the number-based particle size distribution based on a (semi-)automatic quantitative analysis using ImageJ, and (iv) in view of risk assessment, a calculation to estimate the amount of particles available for release from the mask.

JF - Protocol Exchange PB - Creative Commons CY - PO Box 1866, Mountain View, CA 94042 M3 - https://doi.org/10.21203/rs.3.pex-1902/v1 ER - TY - JOUR T1 - Titanium dioxide particles frequently present in face masks intended for general use require regulatory control JF - Scientific Reports Y1 - 2022 A1 - Eveline Verleysen A1 - Ledecq, Marina A1 - Lisa Siciliani A1 - Karlien Cheyns A1 - Christiane Vleminckx A1 - Marie-Noelle Blaude A1 - Sandra De Vos A1 - Frederic Brassinne A1 - Frederic Van Steen A1 - Régis Nkenda A1 - Ronny Machiels A1 - Nadia Waegeneers A1 - Joris Van Loco A1 - Jan Mast VL - 12 CP - 1 M3 - 10.1038/s41598-022-06605-w ER - TY - JOUR T1 - Towards a generic protocol for measuring the constituent particle size distribution of E171 in food by electron microscopy JF - Food Control Y1 - 2022 A1 - Eveline Verleysen A1 - Frederic Brassinne A1 - Frederic Van Steen A1 - Nadia Waegeneers A1 - Karlien Cheyns A1 - Ronny Machiels A1 - Stella Mathioudaki A1 - Isaac Ojea Jimenez A1 - Ledecq, Marina A1 - Jan Mast VL - 132 M3 - 10.1016/j.foodcont.2021.108492 ER - TY - Generic T1 - The Belgian Nanoregister in Figures - Trade Year 2017 Y1 - 2021 A1 - Stella Mathioudaki A1 - Eveline Verleysen A1 - Jan Mast KW - nanomaterials KW - nanoregister KW - Trade year 2017 ER - TY - Generic T1 - The Belgian Nanoregister in Figures - Trade Year 2018 Y1 - 2021 A1 - Stella Mathioudaki A1 - Eveline Verleysen A1 - Jan Mast KW - nanomaterials KW - nanoregister KW - Trade year 2018 ER - TY - JOUR T1 - The Expression of Hemagglutinin by a Recombinant Newcastle Disease Virus Causes Structural Changes and Alters Innate Immune Sensing. JF - Vaccines (Basel) Y1 - 2021 A1 - Ingrao, Fiona A1 - Victoria Duchatel A1 - Rodil, Isabel Fernandez A1 - Mieke Steensels A1 - Eveline Verleysen A1 - Jan Mast A1 - Bénédicte Lambrecht AB -

Recombinant Newcastle disease viruses (rNDV) have been used as bivalent vectors for vaccination against multiple economically important avian pathogens. NDV-vectored vaccines expressing the immunogenic H5 hemagglutinin (rNDV-H5) are considered attractive candidates to protect poultry from both highly pathogenic avian influenza (HPAI) and Newcastle disease (ND). However, the impact of the insertion of a recombinant protein, such as H5, on the biological characteristics of the parental NDV strain has been little investigated to date. The present study compared a rNDV-H5 vaccine and its parental NDV LaSota strain in terms of their structural and functional characteristics, as well as their recognition by the innate immune sensors. Structural analysis of the rNDV-H5 demonstrated a decreased number of fusion (F) and a higher number of hemagglutinin-neuraminidase (HN) glycoproteins compared to NDV LaSota. These structural differences were accompanied by increased hemagglutinating and neuraminidase activities of rNDV-H5. During in vitro rNDV-H5 infection, increased mRNA expression of TLR3, TLR7, MDA5, and LGP2 was observed, suggesting that the recombinant virus is recognized differently by sensors of innate immunity when compared with the parental NDV LaSota. Given the growing interest in using NDV as a vector against human and animal diseases, these data highlight the importance of thoroughly understanding the recombinant vaccines' structural organization, functional characteristics, and elicited immune responses.

VL - 9 CP - 7 M3 - 10.3390/vaccines9070758 ER - TY - JOUR T1 - The Expression of Hemagglutinin by a Recombinant Newcastle Disease Virus Causes Structural Changes and Alters Innate Immune Sensing JF - Vaccines Y1 - 2021 A1 - Ingrao, Fiona A1 - Victoria Duchatel A1 - Rodil, Isabel Fernandez A1 - Mieke Steensels A1 - Eveline Verleysen A1 - Jan Mast A1 - Bénédicte Lambrecht VL - 9 CP - 7 M3 - 10.3390/vaccines9070758 ER - TY - RPRT T1 - IDENTIFICATION, PHYSICOCHEMICAL CHARACTERISATION AND PRELIMINARY RISK ANALYSIS OF TITANIUM DIOXIDE PARTICLES IN FACE MASKS Intermediate report TiO2-Mask COVID-19 project September 2021 Y1 - 2021 A1 - Jan Mast A1 - Marie-Noelle Blaude A1 - Lisa Siciliani A1 - Karlien Cheyns A1 - Nadia Waegeneers A1 - Joris Van Loco A1 - Christiane Vleminckx A1 - Eveline Verleysen AB -

In situ analysis of titanium dioxide (TiO2) particles in face masks demonstrated the presence of agglomerated TiO2 (nano)particles in all examined face masks that contain polyester or polyamide (nylon) fibres, or that are made of non-woven, synthetic fabrics. These particles resemble fibre-grade TiO2 particles. Because there are no methods available for measuring exposure directly, the methodology that ANSES applied to determine the professional exposure limits to titanium dioxide in its nanoform, was applied for a scenario with intensive use of face masks. Our calculations show that a health risk cannot be excluded for most of the examined face masks when intensively used. The applied approach may overestimate the health risks because of the conservative inhalation exposure assumptions. However, for some face masks the amount of titanium dioxide is so high that a health risk cannot be excluded even when only a small fraction of the titanium dioxide particles are released and inhaled. Currently, we have no indications that TiO2 particles are released in amounts which might result in public health risks, but so far, research and publications of TiO2 particles in textiles, and particularly of their release, are limited. In view of EFSA's conclusion that TiO2 cannot be considered any longer as safe to be used as a food additive because a concern for genotoxicity cannot be ruled out, it is advisable to issue precautionary standards to limit the presence of TiO2 particles in face masks.

PB - Sciensano CY - Elsene, Belgium M3 - 10.25608/ba73-8j24 ER - TY - JOUR T1 - METROFOOD-RI: Pilot services with physical, remote and virtual access JF - Measurement: Sensors Y1 - 2021 A1 - Karine Vandermeiren A1 - Subhalakshmi Sharma A1 - Nastasia Belc A1 - Jan Mast A1 - Agnes Matuszczak A1 - karl Presser A1 - Eveline Verleysen A1 - Claudia Zoani A1 - Joris Van Loco KW - ESFRI KW - Food safety and quality KW - Metrology KW - research infrastructure AB -

METROFOOD-RI (www.metrofood.eu) is an ESFRI research infrastructure, funded upon the EU H2020 METROFOOD-PP project for its Preparatory Phase, aiming to establish a new distributed European Research Infrastructure (RI) to promote scientific excellence and increase efficiency in food quality and food safety. It strives to provide and coordinate high-level metrological services on a European scale for researchers, laboratories, food inspection agencies and policymakers.

As part of the preparatory phase towards the legal statute of ERIC (European Research Infrastructure Consortium), a service portfolio is being set up along with its provision diagram. As a test for this model of service provision, three use cases have been defined that are representative of the different types of access that will be provided by METROFOOD-RI:

  1. physical access to a food pilot plant for demonstrating technical solutions and adaptations of food processing technology to minimize acrylamide in bakery products at the National Research & Development Institute for Food Bio-resources (IBA, Romania).
  2. remote access to the transmission electron microscope facility for physicochemical characterization of nanoparticles in food (Sciensano, Belgium).
  3. virtual access to two e-services for open data use, mainly addressed to researchers, laboratories, food inspection agencies and policy makers:

The use cases will help to evaluate the usability of the single access point of the research infrastructure and to fine-tune the access procedures and interfaces with users. This will support the elaboration of the final service chart of METROFOOD-RI including all the potential physical, electronical and integrated services that the infrastructure aims to provide to its users.

The paper will give an overview and first evaluation of the use case service provision and provide an overview of the potential METROFOOD-RI service portfolio.

VL - 18 M3 - 10.1016/j.measen.2021.100309 ER - TY - JOUR T1 - Particle size analysis of pristine food-grade titanium dioxide and E 171 in confectionery products: Interlaboratory testing of a SP-ICP-MS screening method and confirmation with transmission electron microscopy. JF - Food Control Y1 - 2021 A1 - Otmar Geiss A1 - Ivana Bianchi A1 - Chiara Senaldi A1 - Guillaume Bucher A1 - Eveline Verleysen A1 - Nadia Waegeneers A1 - Frederic Brassinne A1 - Jan Mast A1 - Katrin Loeschner A1 - Janja Vidmar A1 - Federica Aureli A1 - Francesco Cubadda A1 - Andrea Raggi A1 - Francesca Iacoponi A1 - Ruud Peters A1 - Anna Undas A1 - Alexandra Müller A1 - Ann-Katrin Meinhardt A1 - Elke Walz A1 - Volker Gräf A1 - Josefa Barrero-Moreno KW - confectionery KW - E 171 KW - Food-grade titanium dioxide KW - Single-particle ICP-MS KW - VALIDATION AB -

Titanium dioxide is a white colourant authorised as food additive E 171 in the EU, where it is used in a range of alimentary products. As these materials may contain a fraction of particulates with sizes below 100 nm and current EU regulation requires specific labelling of food ingredient to indicate the presence of engineered nanomaterials there is now a need for standardised and validated methods to appropriately size and quantify (nano)particles in food matrices. A single-particle inductively coupled plasma mass spectrometry (spICP-MS) screening method for the determination of the size distribution and concentration of titanium dioxide particles in sugar-coated confectionery and pristine food-grade titanium dioxide was developed. Special emphasis was placed on the sample preparation procedure, crucial to reproducibly disperse the particles before analysis. The transferability of this method was tested in an interlaboratory comparison study among seven experienced European food control and food research laboratories equipped with various ICP-MS instruments and using different software packages. The assessed measurands included the particle mean diameter, the most frequent diameter, the percentage of particles (in number) with a diameter below 100 nm, the particles' number concentration and a number of cumulative particle size distribution parameters (D0, D10, D50, D99.5, D99.8 and D100). The evaluated method's performance characteristics were, the within-laboratory precision, expressed as the relative repeatability standard deviation (RSDr), and the between-laboratory precision, expressed as the relative reproducibility standard deviation (RSDR). Transmission electron microscopy (TEM) was used as a confirmatory technique and served as the basis for bias estimation. The optimisation of the sample preparation step showed that when this protocol was applied to the relatively simple sample food matrices used in this study, bath sonication turned out to be sufficient to reach the highest, achievable degree of dispersed constituent particles. For the pristine material, probe sonication was required. Repeatability and reproducibility were below 10% and 25% respectively for most measurands except for the lower (D0) and the upper (D100) bound of the particle size distribution and the particle number concentration. The broader distribution of the lower and the upper bounds could be attributed to instrument-specific settings/setups (e.g. the timing parameters, the transport efficiency, type of mass-spectrometer) and software-specific data treatment algorithms. Differences in the upper bound were identified as being due to the non-harmonised application of the upper counting limit. Reporting D99.5 or D99.8 instead of the effectively largest particle diameter (D100) excluded isolated large particles and considerably improved the reproducibility. The particle number-concentration was found to be influenced by small differences in the sample preparation procedure. The comparison of these results with those obtained using electron microscopy showed that the mean and median particle diameter was, in all cases, higher when using spICP-MS. The main reason for this was the higher size detection limit for spICP-MS plus the fact that some of the analysed particles remained agglomerated/aggregated after sonication. Single particle ICP-MS is a powerful screening technique, which in many cases provides sufficient evidence to confirm the need to label a food product as containing (engineered) titanium dioxide nanomaterial according to the current EU regulatory requirements. The overall positive outcome of the method performance evaluation and the current lack of alternative standardised procedures, would indicate this method as being a promising candidate for a full validation study.

VL - 120 M3 - 10.1016/j.foodcont.2020.107550 ER - TY - JOUR T1 - Physicochemical characterization of nanoparticles in food additives in the context of risk identification JF - EFSA Supporting Publications Y1 - 2021 A1 - Eveline Verleysen A1 - Nadia Waegeneers A1 - Sandra De Vos A1 - Frederic Brassinne A1 - Ledecq, Marina A1 - Frederic Van Steen A1 - Mirjana Andjelkovic A1 - Raphael Janssens A1 - Stella Mathioudaki A1 - Lotte Delfosse A1 - Ronny Machiels A1 - Karlien Cheyns A1 - Jan Mast VL - 18 CP - 6 M3 - 10.2903/sp.efsa.2021.EN-6678 ER - TY - BOOK T1 - Characterization of Nanoparticles: Measurement Processes for Nanoparticles : Characterization of nanomaterials by transmission electron microscopy: Measurement procedures T2 - Characterization of nanomaterials by transmission electron microscopy: Measurement procedures Y1 - 2020 A1 - Jan Mast A1 - Eveline Verleysen A1 - Vasile-Dan Hodoroaba A1 - Ralf Kaegi KW - Characterization KW - nanomaterials KW - transmission electron microscopy AB -

Description

Characterization of Nanoparticles: Measurement Processes for Nanoparticles surveys this fast growing field, including established methods for the physical and chemical characterization of nanoparticles. The book focuses on sample preparation issues (including potential pitfalls), with measurement procedures described in detail. In addition, the book explores data reduction, including the quantitative evaluation of the final result and its uncertainty of measurement. The results of published inter-laboratory comparisons are referred to, along with the availability of reference materials necessary for instrument calibration and method validation. The application of these methods are illustrated with practical examples on what is routine and what remains a challenge.

In addition, this book summarizes promising methods still under development and analyzes the need for complementary methods to enhance the quality of nanoparticle characterization with solutions already in operation.

Key Features

Helps readers decide which nanocharacterization method is best for each measurement problem, including limitations, advantages and disadvantages

Shows which nanocharacterization methods are best for different classes of nanomaterial

Demonstrates the practical use of a method based on selected case studies

Readership

Materials scientists, chemists and chemical engineers who are looking to learn more about nanocharacterization for materials selection at the nanoparticle level

Paperback ISBN: 9780128141823

eBook ISBN: 9780128141830

JF - Characterization of nanomaterials by transmission electron microscopy: Measurement procedures PB - Elsevier SN - 978-0-12-814182-3 ER - TY - JOUR T1 - Increased surface area of halloysite nanotubes due to surface modification predicts lung inflammation and acute phase response after pulmonary exposure in mice JF - Environmental Toxicology and Pharmacology Y1 - 2020 A1 - Barfod, Kenneth Klingenberg A1 - Katja Maria Bendtsen A1 - Trine Berthing A1 - Antti Joonas Koivisto A1 - Sarah S Poulsen A1 - Ester Segal A1 - Eveline Verleysen A1 - Jan Mast A1 - Andreas Holländer A1 - Jensen, Keld Alstrup A1 - Hougaard, Karin S A1 - Vogel, Ulla KW - Acute phase response KW - Airway exposure KW - Comet Assay KW - Halloysite nanotubes KW - High aspect ratio nanomaterial (HARN) AB -

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 in vitro 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 Serumamyloida 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 Saa3 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 mice.

VL - 73 M3 - 10.1016/j.etap.2019.103266 ER - TY - RPRT T1 - NanoRegister Evaluation: "Compliance control and substantive evaluation of the registration of substances produced in nanoparticulate state according to Royal Decree of 27 May 2014” - Trade Year 2017 Y1 - 2020 A1 - Stella Mathioudaki A1 - Eveline Verleysen A1 - Jan Mast KW - compliance KW - nanomaterials KW - Nanoregister database KW - Royal Degree of 27 May 2014 PB - Sciensano/ SPF DG5 ER - TY - RPRT T1 - NanoRegister Evaluation: "Compliance control and substantive evaluation of the registration of substances produced in nanoparticulate state according to Royal Decree of 27 May 2014” - Trade Year 2018 Y1 - 2020 A1 - Stella Mathioudaki A1 - Eveline Verleysen A1 - Jan Mast KW - EVALUATION KW - nanomaterials KW - nanoregister KW - Royal Decree of 27th May 2014 PB - Sciensano CY - Brussels, Belgium ER - TY - JOUR T1 - Physico-chemical characterisation of the fraction of silver (nano)particles in pristine food additive E174 and in E174-containing confectionery. JF - Food Addit Contam Part A Chem Anal Control Expo Risk Assess Y1 - 2020 A1 - Sandra De Vos A1 - Nadia Waegeneers A1 - Eveline Verleysen A1 - Karen Smeets A1 - Jan Mast KW - E174 KW - particle size distribution KW - Silver KW - Single particle ICP-MS KW - TEM AB -

Silver (E174) is authorised as a food additive in the EU. The unknown particle size distribution of E174 is a specific concern for the E174 risk assessment. This study characterised the fraction of silver (nano)particles in 10 commercially available pristine E174 food additives and 10 E174-containing products by transmission electron microscopy (TEM) and single-particle inductively coupled plasma-mass spectrometry (spICP-MS). TEM analysis showed that all samples contained micrometre-sized flakes and also a fraction of (nano)particles. Energy-dispersive X-ray spectroscopy (EDX) and electron diffraction confirmed that the (nano)particles and micrometre-sized flakes consisted of silver. A higher amount of (nano)particles was observed in the products than in the food additives. In addition, the surface of the micrometre-sized flakes was rougher in products. The median of the minimum external dimension, assessed as minimal Feret diameter, of the fraction of (nano)particles determined by quantitative TEM analysis was 11 ± 4 nm and 18 ± 7 nm (overall mean ± standard deviation), for food additives and products, respectively. Similar size distributions were obtained by spICP-MS and TEM, considering the limit of detection of spICP-MS. The median of the equivalent spherical diameter of the fraction of (nano)particles determined by spICP-MS was 19 ± 4 nm and 21 ± 2 nm (overall mean ± standard deviation), for food additives and products, respectively. In all samples, independent of the choice of technique, the nano-sized particles represented more than 97% (by number) of the silver particles, even though the largest mass of silver was present as flakes.

M3 - 10.1080/19440049.2020.1809719 ER - TY - JOUR T1 - Physico-chemical characterisation of the fraction of silver (nano)particles in pristine food additive E174 and in E174-containing confectionery JF - Food Additives & Contaminants: Part A Y1 - 2020 A1 - Sandra De Vos A1 - Nadia Waegeneers A1 - Eveline Verleysen A1 - Karen Smeets A1 - Jan Mast KW - E174 KW - food additive KW - silverparticle size distribution KW - spICP-MS KW - TEM AB -

Silver (E174) is authorised as a food additive in the EU. The unknown particle size distribution of E174 is a specific concern for the E174 risk assessment. This study characterised the fraction of silver (nano)particles in 10 commercially available pristine E174 food additives and 10 E174-containing products by transmission electron microscopy (TEM) and single-particle inductively coupled plasma-mass spectrometry (spICP-MS). TEM analysis showed that all samples contained micrometre-sized flakes and also a fraction of (nano)particles. Energy-dispersive X-ray spectroscopy (EDX) and electron diffraction confirmed that the (nano)particles and micrometre-sized flakes consisted of silver. A higher amount of (nano)particles was observed in the products than in the food additives. In addition, the surface of the micrometre-sized flakes was rougher in products. The median of the minimum external dimension, assessed as minimal Feret diameter, of the fraction of (nano)particles determined by quantitative TEM analysis was 11 ± 4 nm and 18 ± 7 nm (overall mean ± standard deviation), for food additives and products, respectively. Similar size distributions were obtained by spICP-MS and TEM, considering the limit of detection of spICP-MS. The median of the equivalent spherical diameter of the fraction of (nano)particles determined by spICP-MS was 19 ± 4 nm and 21 ± 2 nm (overall mean ± standard deviation), for food additives and products, respectively. In all samples, independent of the choice of technique, the nano-sized particles represented more than 97% (by number) of the silver particles, even though the largest mass of silver was present as flakes.

VL - 37 CP - 11 M3 - 10.1080/19440049.2020.1809719 ER - TY - JOUR T1 - Physicochemical Characterization of the Pristine E171 Food Additive by Standardized and Validated Methods. JF - Nanomaterials (Basel) Y1 - 2020 A1 - Eveline Verleysen A1 - Nadia Waegeneers A1 - Frederic Brassinne A1 - Sandra De Vos A1 - Isaac Ojea Jimenez A1 - Stella Mathioudaki A1 - Jan Mast KW - E171 KW - food additive KW - Single particle ICP-MS KW - transmission electron microscopy AB -

E171 (titanium dioxide) is a food additive that has been authorized for use as a food colorant in the European Union. The application of E171 in food has become an issue of debate, since there are indications that it may alter the intestinal barrier. This work applied standardized and validated methodologies to characterize representative samples of 15 pristine E171 materials based on transmission electron microscopy (TEM) and single-particle inductively coupled plasma mass spectrometry (spICP-MS). The evaluation of selected sample preparation protocols allowed identifying and optimizing the critical factors that determine the measurement of the particle size distribution by TEM. By combining optimized sample preparation with method validation, a significant variation in the particle size and shape distributions, the crystallographic structure (rutile versus anatase), and the physicochemical form (pearlescent pigments versus anatase and rutile E171) was demonstrated among the representative samples. These results are important for risk assessment of the E171 food additive and can contribute to the implementation of the European Food Safety Authority (EFSA) guidance on risk assessment of the application of nanoscience and nanotechnologies in the food and feed chain.

VL - 10 CP - 3 M3 - 10.3390/nano10030592 ER - TY - Generic T1 - Automation and validation of TEM characterization methods Y1 - 2019 A1 - Eveline Verleysen JF - Workshop: Physicochemical characterisation of nano-sized particles in food CY - Tervuren, Belgium ER - TY - Generic T1 - Characterization of pristine food additives by TEM Y1 - 2019 A1 - Eveline Verleysen JF - Workshop: Physicochemical characterisation of nano-sized particles in food CY - Tervuren, Belgium ER - TY - Generic T1 - Characterization of the nano-sized fraction of silver particles in food additive E174 by EM and sp-ICP-MS Y1 - 2019 A1 - Sandra De Vos A1 - Eveline Verleysen A1 - M. Ledecq A1 - Nadia Waegeneers A1 - Jan Mast JF - IMEKOFOODS 4 ER - TY - Generic T1 - Combining TEM with single particle ICP-MS: assessing the size of individual nanoparticles in food additives by multiple techniques Y1 - 2019 A1 - Nadia Waegeneers A1 - Delfosse,L. A1 - Sandra De Vos A1 - Eveline Verleysen A1 - Jan Mast KW - Single particle ICP-MS KW - transmission electron microscopy JF - Workshop: Physicochemical characterisation of nano-sized particles in food PB - Sciensano CY - Brussels, Belgium CP - Sciensano ER - TY - Generic T1 - Demo: identification and measurement of nano-sized particles in a food products using a remote controlled analytical TEM (Talos, Thermo Fisher Scientific) T2 - Workshop: Physicochemical characterisation of nano-sized particles in food Y1 - 2019 A1 - Eveline Verleysen KW - TEM KW - Workshop AB -

SCOPE OF THE WORKSHOP

JF - Workshop: Physicochemical characterisation of nano-sized particles in food CY - Tervuren, Belgium ER - TY - JOUR T1 - Estimation of the Uncertainties Related to the Measurement of the Size and Quantities of Individual Silver Nanoparticles in Confectionery. JF - Materials (Basel) Y1 - 2019 A1 - Nadia Waegeneers A1 - Sandra De Vos A1 - Eveline Verleysen A1 - Ann Ruttens A1 - Jan Mast KW - Single particle ICP-MS AB -

E174 (silver) is a food additive that may contain silver nanoparticles (AgNP). Validated methods are needed to size and quantify these particles in a regulatory context. However, no validations have yet been performed with food additives or real samples containing food additives requiring a sample preparation step prior to analysis. A single-particle inductively coupled plasma mass spectrometry (spICP-MS) method was developed and validated for sizing and quantifying the fraction of AgNP in E174 and in products containing E174, and associated uncertainties related to sample preparation, analysis and data interpretation were unraveled. The expanded measurement uncertainty for AgNP sizing was calculated to be 16% in E174-containing food products and increased up to 23% in E174 itself. The E174 food additives showed a large silver background concentration combined with a relatively low number of nanoparticles, making data interpretation more challenging than in the products. The standard uncertainties related to sample preparation, analysis, and challenging data interpretation were respectively 4.7%, 6.5%, and 6.0% for triplicate performances. For a single replicate sample, the uncertainty related to sample preparation increased to 6.8%. The expanded measurement uncertainty related to the concentration determination was 25-45% in these complex samples, without a clear distinction between additives and products. Overall, the validation parameters obtained for spICP-MS seem to be fit for the purpose of characterizing AgNP in E174 or E174-containing products.

VL - 12 CP - 17 M3 - 10.3390/ma12172677 ER - TY - JOUR T1 - Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials JF - Materials Y1 - 2019 A1 - Eveline Verleysen A1 - Thorsten Wagner A1 - Hans-Gerd Lipinski A1 - Ralf Kägi A1 - Robert Koeber A1 - Ana Boix-Sanfeliu A1 - Pieter-Jan De Temmerman A1 - Jan Mast KW - electron microscopy KW - European Commission’s Recommendation for a definition of a nanomaterial KW - image analysis KW - Method validation KW - nanomaterial KW - particulate material AB -

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 efficiency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.

VL - 12 CP - 14 M3 - 10.3390/ma12142274 ER - TY - JOUR T1 - Evaluation of a TEM based Approach for Size Measurement of Particulate (Nano)materials. JF - Materials (Basel) Y1 - 2019 A1 - Eveline Verleysen A1 - Thorsten Wagner A1 - Hans-Gerd Lipinski A1 - Ralf Kägi A1 - Robert Koeber A1 - Ana Boix-Sanfeliu A1 - Pieter-Jan De Temmerman A1 - Jan Mast AB -

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 efficiency for the accurate and precise size measurement of the particulate materials. The approach is shown to be implementable in many other electron microscopy laboratories.

VL - 12 CP - 14 M3 - 10.3390/ma12142274 ER - TY - Generic T1 - Inauguration event Talos electron microscope: The Talos in practice Y1 - 2019 A1 - Eveline Verleysen CY - Uccle, Belgium ER - TY - Generic T1 - Increased surface area of halloysite nanotubes due to surface modification predicts lung inflammation and acute phase response after pulmonary exposure in mice Y1 - 2019 A1 - Kenneth Klingenberg Barfod A1 - Katja Maria Bendtsen A1 - Trine Berthing A1 - Antti Joonas Koivisto A1 - Sarah Søs Poulsen A1 - Ester Segal A1 - Eveline Verleysen A1 - Jan Mast A1 - Andreas Holländer A1 - Keld Alstrup Jensen A1 - Karin Sørig Hougaard A1 - Ulla Vogel KW - halloysite KW - nanotubes KW - pulmonary exposure AB -

presentation at the Annual meeting in Danish Society for Pharmacology and Toxicology 2019, Sønderborg, Denmark

JF - Annual meeting in Danish Society for Pharmacology and Toxicology CY - Sønderborg, Denmark UR - https://dstf.dk/annual-meeting-2019/ ER - TY - Generic T1 - Increased surface area of halloysite nanotubes due to surface modification predicts lung inflammation and acute phase response after pulmonary exposure in mice Y1 - 2019 A1 - Kenneth Klingenberg Barfod A1 - Katja Maria Bendtsen A1 - Trine Berthing A1 - Antti Joonas Koivisto A1 - Sarah Søs Poulsen A1 - Ester Segal A1 - Eveline Verleysen A1 - Jan Mast A1 - Andreas Holländer A1 - Keld Alstrup Jensen A1 - Karin Sørig Hougaard A1 - Vogel, Ulla JF - Nanosafety Cluster Week. Building confidence in risk assessment and governance of Nanomaterial Innovation CY - Copenhagen, Denmark ER - TY - BOOK T1 - Nanomaterials for food applications : Analytical challenges and practical solutions for enforcing labeling of nanoingredients in food products in the European Union T2 - Analytical challenges and practical solutions for enforcing labeling of nanoingredients in food products in the European Union Y1 - 2019 A1 - M. Correia A1 - Eveline Verleysen A1 - K. Loeschner KW - analysis KW - electron microscopy KW - Field-flow fractionation KW - food KW - Food Additives KW - Ingredients KW - labeling KW - nanomaterials KW - Nanoparticles KW - Single particle ICP-MS AB -

Food ingredients present in the form of engineered nanoparticles (NPs) require specific labeling as “nano” in the European Union. Enforcing proper labeling of “nano” labeling poses several analytical challenges. This includes the many potential sources of NPs in food which can interfere with the analysis, the challenges in relation to sample preparation, the limitations of existing analytical techniques, and the lack of validated studies and reference materials. This book chapter summarizes these challenges and, in addition, suggests a screening strategy for inorganic NPs in food. It further highlights the future challenges of analyzing organic and carbon-based nanomaterials.

JF - Analytical challenges and practical solutions for enforcing labeling of nanoingredients in food products in the European Union PB - Elsevier SN - 978-0-12-814130-4 M3 - https://doi.org/10.1016/B978-0-12-814130-4.00010-5 ER - TY - RPRT T1 - Nanopack Deliverable 6.2: Title: Manuscript with physico-chemical characterisation of HNTs and HNT hazard characterization Y1 - 2019 A1 - Karin Sørig Hougaard A1 - Kenneth Klingenberg Barfod A1 - Katja Maria Bendtsen A1 - Trine Berthing A1 - Antti Joonas Koivisto A1 - Sarah Søs Poulsen A1 - Ester Segal A1 - Eveline Verleysen A1 - Jan Mast A1 - Andreas Holländer A1 - Keld Alstrup Jensen A1 - Vogel, Ulla KW - hallosite nanotubes KW - hazard characterisation KW - Nanoparticles KW - physico-chemical characterization AB -

report for Manuscript with physico-chemical characterisation of HNTs and HNT hazard characterization

ER - TY - Generic T1 - Open Lab Application for the Characterization of Nanomaterials by Transmission Electron Microscopy Y1 - 2019 A1 - Karine Vandermeiren A1 - Eveline Verleysen A1 - Jan Mast A1 - Joris Van Loco KW - Food Analysis KW - Metrofood-RI KW - nanomaterials KW - open laboratory KW - physico-chemical characterization AB -

OPEN LAB APPLICATION FOR THE CHARACTERIZATION OF NANOMATERIALS BY TRANSMISSION ELECTRON MICROSCOPY

Karine Vandermeiren(1), Eveline Verleysen(1), Jan Mast(1), Joris Van Loco*(1)

1) Sciensano, Belgium

*Corresponding author - E-mail: Joris.VanLoco@sciensano.be

Applications of nanotechnologies in the food sector are rapidly growing in several areas such as food processing, packaging, nutraceutical delivery, quality control, and functional foods to even the use of nanosensors to assure food quality and safety. Since it is widely expected that more and more nanotechnology based products will become available in the European Union over the coming years, the European Commission (EC) has developed a Recommendation that provides a basis to determine whether a material should be considered as a nanomaterial (NM) for legislative and policy purposes in the EU (2011/696/EU). The aim is to further apply and adapt this current Recommendation to sector specific needs such as food and food contact materials, biocidal products, cosmetics and medical devices. As a consequence there is a growing need for validated characterization methods and for certified materials facilitating the implementation of the EC Recommendation and sector-specific regulations. The physical and chemical characterization of NM in complex matrices like food is an extremely challenging task requiring expert knowledge and modern instrumentation. The application of electron microscopy (EM) for the characterization of NM is advised in several international guidelines, including guidelines of the European Food Safety Authority (EFSA) and the Scientific Committee on emerging and Newly Identified Health Risks (SCENIHR). However, EM based methodologies are cost- and labor-intensive and such dedicated infrastructures remain limited to specialized research institutions. Over the last years the National Reference Laboratory for Nanomaterials in Food of Sciensano (Belgium) has acquired high level expertise and instrumentation to measure the size, morphology, crystallographic structure and chemical composition of a wide range of NM by EM. Identification and measurement of particles can be performed in complex matrices such as food, cosmetics, medicines and environmental samples. A high degree of automation of the EM imaging and image analysis was recently developed to facilitate the measurement of particle size and shape distributions. Within the context of the METROFOOD-RI “Infrastructure for promoting Metrology in Food and Nutrition” this facility will be further developed as a test case for an open laboratory application to be shared with interested universities, research institutes or companies, ultimately allowing remote operation of the EM and monitoring via VPN-connection.

JF - Recent Advances in Food Analysis (RAFA) PB - University of Chemistry and Technology, Prague, Czech Republic CY - Prague, Czech Republic SN - 978-80-7592-055-3 UR - http://www.rafa2019.eu/pdf/RAFA2019_BoA_web.pdf ER - TY - Generic T1 - Optimization and validation of quantitative TEM analysis of pristine titanium dioxide powders in a regulatory context Y1 - 2019 A1 - Frederic Brassinne A1 - Sandra De Vos A1 - Eveline Verleysen A1 - M. Ledecq A1 - Jan Mast JF - IMEKOFOODS 4 ER - TY - Generic T1 - Our new analytical electron microscope is way better than our conventional one Y1 - 2019 A1 - Frederic Brassinne A1 - Sandra De Vos A1 - Eveline Verleysen A1 - Daisy Tysmans A1 - Jan Mast JF - Inauguration Talos analytical electron microscope CP - Sciensano - Trace Elements and nanomaterials ER - TY - Generic T1 - Physicochemical characterisation of several types of the E171 food additive Y1 - 2019 A1 - Eveline Verleysen A1 - M. Ledecq A1 - Sandra De Vos A1 - I. Ojea Jimenez A1 - Frederic Brassinne A1 - Nadia Waegeneers A1 - Jan Mast KW - Characterization KW - E171 KW - electron microscopy KW - particle size distributions. KW - single particle inductively coupled plasma mass spectroscopy KW - titanium oxide AB -

The application of E171 (titanium dioxide) as a food additive has been an issue of debate in the European Union. A detailed physicochemical characterization of the E171 particles can objectify the discussions and is essential in the context of risk analysis.
This work focuses on the physicochemical characterization of 15 pristine E171 materials by transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectroscopy (sp-ICP-MS) following CEN/TC 352 guidelines. The E171 samples were purchased on the Belgian market or were obtained from European producers.
In optimized conditions, representative TEM micrographs could be recorded and the ParticleSizer image analysis software succeeded in applying noise reduction and background subtraction, allowing robust automatic thresholding and constituent particle detection. The large majority of constituent particles, confirmed to be TiO2 by energy dispersive X-ray spectroscopy (EDX), were reliably detected and measured by the software. The measurement uncertainty budgets of particle sizing by TEM and sp-ICP-MS are in the order of 10% and 16 % (Ucx, k=2), respectively, based on validation studies of a series of representative test materials. The phase of the E171 particles was determined by powder electron diffraction.
Several types of TiO2 particles were found in pristine E171. These types were shown to be applied as well in food products containing E171. All examined E171 food additives contained a significant amount of nanoparticles. In the most dispersed state, the particle size measurements by TEM and sp-ICP-MS agreed well. Eleven E171 materials consisted of anatase. Three materials consisted of smaller rutile TiO2 particles (20-40 nm) coated on mica. One material contained a mixture of anatase and rutile particles.
In future research, the methodology will be implemented in a systematic and larger scale study of E171 food additives and food items containing E171, available on the market.

JF - IMEKOFOODS 4 UR - https://www.imekofoods4.be/ ER - TY - Generic T1 - Physicochemical Characterisation of the E171 Food Additive Y1 - 2019 A1 - Eveline Verleysen A1 - Marina Ledecq A1 - Sandra De Vos A1 - Isaac Ojea Jimenez A1 - Nadia Waegeneers A1 - Frederic Brassinne A1 - Jan Mast KW - E171 KW - particle size distribution KW - Single particle ICP-MS KW - titanium dioxide KW - transmission electron microscopy AB -

The application of E171 (titanium dioxide) as a food additive has been an issue of debate in the European Union. A detailed physicochemical characterization of the E171 particles can objectify the discussions and is essential in the context of risk analysis. This work focuses on the physicochemical characterization of 15 pristine E171 materials by transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectroscopy (sp-ICP-MS) following CEN/TC 352 guidelines. The E171 samples were purchased on the Belgian market or were obtained from European producers. To measure the minimal external dimension of the constituent particles of E171, sample preparation protocols influencing particle dispersion (pH, probe sonication and centrifugation) were tested and optimized. In optimized conditions, representative TEM micrographs could be recorded, and it was demonstrated that all examined E171 food additives contained a significant amount of nanoparticles. The large majority of constituent particles, confirmed to be TiO2 by energy dispersive X-ray spectroscopy (EDX), were reliably detected and measured using the ParticleSizer software. In the most dispersed state, the particle size measurements by TEM and sp-ICP-MS agreed well. The measurement uncertainty budgets of particle sizing by TEM and sp-ICP-MS are in the order of 10% and 16 % (Ucx, k=2), respectively, based on validation studies of a series of representative test materials. Electron diffraction demonstrated that both anatase and rutile TiO2 particles were found in pristine E171. Eleven E171 materials consisted of anatase. Three materials consisted of smaller rutile TiO2 particles (20-40 nm) coated on mica. One material contained a mixture of anatase and rutile particles. In future research, the methodology will be implemented in a systematic and larger scale study of E171 food additives and food items containing E171, available on the market.

JF - Recent Advances in Food Analysis (RAFA) PB - University of Chemistry and Technology, Prague, Czech Republic CY - Prague, Czech Republic SN - 978-80-7592-055-3 UR - http://www.rafa2019.eu/pdf/RAFA2019_BoA_web.pdf ER - TY - Generic T1 - Possible solutions to analytical challenges Y1 - 2019 A1 - Frederic Brassinne A1 - Eveline Verleysen A1 - Jan Mast KW - Nanoparticles JF - Workshop: Physicochemical characterisation of nano-sized particles in food ER - TY - RPRT T1 - RF 16/6306 Implementation and validation of an analytical methodology to assess engineered nanomaterials in food additives Nanofood@ Y1 - 2019 A1 - Eveline Verleysen A1 - Sandra De Vos A1 - Nadia Waegeneers A1 - Frederic Brassinne A1 - Stella Mathioudaki A1 - Marina Ledecq A1 - Lotte Delfosse A1 - Jan Mast ER - TY - Generic T1 - Syllabus of the Interactive infosession on the methodologies and reporting of the characterisation of nanoparticles in food additives and novel food (FAVV/AFSCA) Y1 - 2019 A1 - Jan Mast A1 - Eveline Verleysen ER - TY - Generic T1 - Syllabus of the workshop physicochemical characterization of nano-sized particles in food Y1 - 2019 A1 - Eveline Verleysen A1 - Ralf Kaegi A1 - Nadia Waegeneers A1 - Stella Mathioudaki A1 - Frederic Brassinne A1 - Jan Mast KW - Nanoparticles KW - physico-chemical characterization KW - transmission electron microscopy AB -

Scope of this workshop

ER - TY - Generic T1 - Validation of single particle ICP-MS for routine sizing and quantification of the fraction of silver nanoparticles in E174 food addititves and confectionery products Y1 - 2019 A1 - Nadia Waegeneers A1 - Sandra De Vos A1 - Eveline Verleysen A1 - Jan Mast KW - Nanomaterials; Food additives; E174; Silver AB -

Silver (Ag) is a food additive (E174) approved by the European Commission to be used for the external coating of confectionery, for decoration of chocolates, and in liqueurs [1]. It is commercially distributed in its pristine powder and sheet form, and in confectionery products. Due to its nature, E174 may contain silver nanoparticles, which implies a need for validated methods to size and quantify these particles. Single particle inductively coupled plasma-mass spectrometry (spICP-MS) is thereby a promising technique as it is capable of sizing and counting particles at the same time.
A spICP-MS method was developed and validated for sizing and quantifying the fraction of silver nanoparticles in E174 food additives and in products containing E174. The samples were prepared for analysis according to a slightly modified version of the method of Jensen et al. [2]. The E174 food additives showed a large silver background concentration combined with a relatively low number of nanoparticles, making the quantification of the nanoparticles more challenging than in the products containing E174. Validation of the method showed good performance with respect for the size distribution compared to the size distribution obtained from transmission electron microscopy. Depending on the sample and the background silver concentration, particles with an equivalent spherical diameter (ESD) down to 11 nm could be detected. The performance in terms of repeatability (size 4-11%, concentration 16-29%), and intermediate precision (size 2-8%, concentration 18-31%) depended on the type of sample. The large repeatability compared to the intermediate precision demonstrates the need to analyze multiple independent replicates under routine conditions. When analyzing three replicates, the extended measurement uncertainty (k = 2) on the mean ESD is 20% for E174 food additives and 11% for products containing E174. The quantification of the mass and number concentration is more challenging with extended measurement uncertainties up to 45%.

JF - IMEKOFOODS 4 CP - IMEKO ER - TY - Generic T1 - Characterization of the nano-sized fraction of particles in food additives E174, E175 and E171 Y1 - 2018 A1 - Eveline Verleysen KW - Food Additives KW - nanomaterials AB -

presentation at the 2nd Workshop 'Nano in Belgium'

JF - 2nd nano in Belgium workshop PB - the Belgian EU-OSHA Focal point CY - Brussels, Belgium ER - TY - Generic T1 - Characterization of the TiO2 E171 food additive Y1 - 2018 A1 - Frederic Brassinne A1 - Sandra De Vos A1 - Eveline Verleysen A1 - Pieter-Jan De Temmerman A1 - M. Ledecq A1 - Jan Mast JF - Toxicology Letters VL - 295 M3 - 10.1016/j.toxlet.2018.06.909 ER - TY - RPRT T1 - Physico-chemical characterization of the fraction of engineered nanomaterials in silver food additives (E174) in the context of risk assessment (nanoAg@) Y1 - 2018 A1 - Eveline Verleysen A1 - Sandra De Vos A1 - Nadia Waegeneers A1 - Lotte Delfosse A1 - Marina Ledecq A1 - Jan Mast AB -

report of project nanoAg@

UR - https://www.sciensano.be/en/projects/physico-chemical-characterization-fraction-engineered-nanomaterials-silver-e174-food-additives ER - TY - BOOK T1 - Physical Characterization of Nanomaterials in Dispersion by Transmission Electron Microscopy in a Regulatory Framework T2 - Physical characterization of nanomaterials in dispersion by transmission electron microscopy in a regulatory framework Y1 - 2015 A1 - Jan Mast A1 - Eveline Verleysen A1 - Pieter-Jan De Temmerman ED - Francis Leonard Deepak ED - Alvaro Mayoral ED - Raul Arenal AB -

TEM is one of the few techniques that can identify nanoparticles according to the current definitions. This chapter focuses on the different steps required to analyze dispersed nanomaterials by TEM. Methodologies to obtain homogeneous and stable dispersions of colloidal nanomaterials and powders are presented. The preparation of TEM specimens to obtain a representative distribution of particles on the grid is discussed. The application of TEM imaging methods, electron diffraction and analytical TEM to obtain complementary information on the size, morphology, crystallographic structure, electronic structure and composition of nanomaterials is reviewed.

In a qualitative TEM analysis the key properties of the physical form of the nanomaterial under which it is exposed to in vitro and in vivo test systems are described based on TEM micrographs. Subsequently, a quantitative analysis which includes detection, classification and measurement of primary particle properties, and validation of the measurement results can be performed. The possibility to extract 3D information by fractal analysis of electron micrographs of aggregated nanomaterials with a fractal-like structure is explored

JF - Physical characterization of nanomaterials in dispersion by transmission electron microscopy in a regulatory framework PB - Springer International Publishing CY - Cham VL - Advanced Transmission Electron Microscopy. Applications to Nanomaterials SN - 978-3-319-15176-2 CP - 8 M3 - 10.1007/978-3-319-15177-910.1007/978-3-319-15177-9_8 ER - TY - JOUR T1 - TEM and SP-ICP-MS analysis of the release of silver nanoparticles from decoration of pastry. JF - J Agric Food Chem Y1 - 2015 A1 - Eveline Verleysen A1 - Van Doren, E A1 - Nadia Waegeneers A1 - Pieter-Jan De Temmerman A1 - M Abi Daoud Francisco A1 - Jan Mast KW - Food Additives KW - Mass Spectrometry KW - Metal Nanoparticles KW - Microscopy, Electron, Transmission KW - Particle Size KW - Silver KW - X-Ray Diffraction AB - Metallic silver is an EU approved food additive referred to as E174. It is generally assumed that silver is only present in bulk form in the food chain. This work demonstrates that a simple treatment with water of "silver pearls", meant for decoration of pastry, results in the release of a subfraction of silver nanoparticles. The number-based size and shape distributions of the single, aggregated, and/or agglomerated particles released from the silver pearls were determined by combining conventional bright-field TEM imaging with semiautomatic particle detection and analysis. In addition, the crystal structure of the particles was studied by electron diffraction and chemical information was obtained by combining HAADF-STEM imaging with EDX spectroscopy and mapping. The TEM results were confirmed by SP-ICP-MS. The representative Ag test nanomaterial NM-300 K was used as a positive control to determine the uncertainty on the measurement of the size and shape of the particles. VL - 63 CP - 13 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25768118?dopt=Abstract M3 - 10.1021/acs.jafc.5b00578 ER - TY - JOUR T1 - Genotoxicity evaluation of nanosized titanium dioxide, synthetic amorphous silica and multi-walled carbon nanotubes in human lymphocytes. JF - Toxicol In Vitro Y1 - 2014 A1 - Tavares, Ana M A1 - Louro, Henriqueta A1 - Antunes, Susana A1 - Quarré, Stephanie A1 - Simar, Sophie A1 - Pieter-Jan De Temmerman A1 - Eveline Verleysen A1 - Jan Mast A1 - Jensen, Keld A A1 - Norppa, Hannu A1 - Nesslany, Fabrice A1 - Silva, Maria João KW - Adult KW - Female KW - Humans KW - In Vitro Techniques KW - Light KW - Lymphocytes KW - Male KW - Micronucleus Tests KW - Microscopy, Electron, Transmission KW - Mutagenicity Tests KW - Nanostructures KW - Nanotubes, Carbon KW - Particle Size KW - Scattering, Radiation KW - Silicon Dioxide KW - Titanium AB -

Toxicological characterization of manufactured nanomaterials (NMs) is essential for safety assessment, while keeping pace with innovation from their development and application in consumer products. The specific physicochemical properties of NMs, including size and morphology, might influence their toxicity and have impact on human health. The present work aimed to evaluate the genotoxicity of nanosized titanium dioxide (TiO2), synthetic amorphous silica (SAS) and multiwalled carbon nanotubes (MWCNTs), in human lymphocytes. The morphology and size of those NMs were characterized by transmission electron microscopy, while the hydrodynamic particle size-distributions were determined by dynamic light scattering. Using a standardized procedure to ensure the dispersion of the NMs and the cytokinesis-block micronucleus assay (without metabolic activation), we observed significant increases in the frequencies of micronucleated binucleated cells (MNBCs) for some TiO2 NMs and for two MWCNTs, although no clear dose-response relationships could be disclosed. In contrast, all forms of SAS analyzed in this study were unable to induce micronuclei. The present findings increase the weight of evidence towards a genotoxic effect of some forms of TiO2 and some MWCNTs. Regarding safety assessment, the differential genotoxicity observed for closely related NMs highlights the importance of investigating the toxic potential of each NM individually, instead of assuming a common mechanism and equal genotoxic effects for a set of similar NMs.

VL - 28 CP - 1 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23811260?dopt=Abstract M3 - 10.1016/j.tiv.2013.06.009 ER - TY - JOUR T1 - Measurement uncertainties of size, shape, and surface measurements using transmission electron microscopy of near-monodisperse, near-spherical nanoparticles JF - Journal of Nanoparticle Research Y1 - 2014 A1 - Pieter-Jan De Temmerman A1 - Lammertyn, Jeroen A1 - De Ketelaere, Bart A1 - Kestens, Vikram A1 - Roebben, Gert A1 - Eveline Verleysen A1 - Jan Mast KW - Transmission electron microscopy Method validation Reference material Silica nanoparticles Measurement uncertainty Nanometrology VL - 16492008221027594757410103241512943 CP - 133624524212031 M3 - 10.1007/s11051-013-2177-1 ER - TY - JOUR T1 - Quantitative characterization of aggregated and agglomerated titanium dioxide nanomaterials by transmission electron microscopy JF - Powder Technology Y1 - 2014 A1 - Eveline Verleysen A1 - Pieter-Jan De Temmerman A1 - Van Doren, E. A1 - M. Abi Daoud Francisco A1 - Jan Mast KW - Titanium dioxide Nanoparticles Size distribution Shape distribution Transmission electron microscopy Dispersion protocol VL - 258 M3 - 10.1016/j.powtec.2014.03.010 ER - TY - JOUR T1 - Semi-automatic size measurement of primary particles in aggregated nanomaterials by transmission electron microscopy JF - Powder Technology Y1 - 2014 A1 - Pieter-Jan De Temmerman A1 - Eveline Verleysen A1 - Lammertyn, Jeroen A1 - Jan Mast KW - Transmission electron microscopy Image analysis Aggregate Nanomaterial Primary particles Fractal analysis VL - 261 M3 - 10.1016/j.powtec.2014.04.040 ER - TY - JOUR T1 - Size measurement uncertainties of near-monodisperse, near-spherical nanoparticles using transmission electron microscopy and particle-tracking analysis JF - Journal of Nanoparticle Research Y1 - 2014 A1 - Pieter-Jan De Temmerman A1 - Eveline Verleysen A1 - Lammertyn, Jeroen A1 - Jan Mast KW - Transmission electron microscopy Particle-tracking analysis Colloidal gold Polystyrene beads Method validation Measurement uncertainty Nanometrology VL - 16 CP - 10 M3 - 10.1007/s11051-014-2628-3 ER - TY - JOUR T1 - Effects of lung exposure to carbon nanotubes on female fertility and pregnancy. A study in mice. JF - Reprod Toxicol Y1 - 2013 A1 - Hougaard, Karin S A1 - Jackson, Petra A1 - Kyjovska, Zdenka O A1 - Birkedal, Renie K A1 - Pieter-Jan De Temmerman A1 - Brunelli, Andrea A1 - Eveline Verleysen A1 - Madsen, Anne Mette A1 - Saber, Anne T A1 - Pojana, Giulio A1 - Jan Mast A1 - Marcomini, Antonio A1 - Jensen, Keld A A1 - Wallin, Håkan A1 - Szarek, Józef A1 - Mortensen, Alicja A1 - Vogel, Ulla KW - Animals KW - Bronchoalveolar Lavage Fluid KW - Female KW - Fertility KW - Liver KW - Lung KW - Male KW - mice KW - Mice, Inbred C57BL KW - Motor Activity KW - Nanotubes, Carbon KW - Pneumonia KW - Pregnancy KW - Reflex, Startle KW - Spermatogenesis AB -

We studied the effects of preconceptional exposure to multiwalled carbon nanotubes (MWCNTs): mature, female C57BL/6J mice were intratracheally instilled with 67μg NM-400 MWCNT, and the following day co-housed with mature males, in breeding pairs. Time to delivery of the first litter, litter parameters, maternal inflammation and histopathology of lung and liver were recorded. In male offspring, locomotor activity, startle response, and daily sperm production (DSP) were assessed. In the dams, lung and liver bore evidence of MWCNT exposure when assessed 6 weeks and 4 months after exposure. A short delay in the delivery of the first litter was observed in exposed females. Litter parameters, behavior and DSP were similar in control and exposed groups. In conclusion, instillation of a single dose of MWCNT induced long lasting pathological changes in dam lung and liver. Theoretically, lung inflammation due to particle exposure could interfere with female reproductive parameters. Whether the observed lag in delivery of a first litter was in fact caused by exposure to MWCNT should be addressed in a study designed specifically to elucidate effects on the early processes involved in establishment of pregnancy. Exposure was not associated with changes in the assessed gestational or offspring parameters.

VL - 41 U1 - http://www.ncbi.nlm.nih.gov/pubmed/23714338?dopt=Abstract M3 - 10.1016/j.reprotox.2013.05.006 ER - TY - JOUR T1 - Quantitative characterization of agglomerates and aggregates of pyrogenic and precipitated amorphous silica nanomaterials by transmission electron microscopy. JF - J Nanobiotechnology Y1 - 2012 A1 - Pieter-Jan De Temmerman A1 - Van Doren, Elke A1 - Eveline Verleysen A1 - Yves Van der Stede A1 - Michel Abi Daoud Francisco A1 - Jan Mast KW - Chemical Precipitation KW - Microscopy, Electron, Transmission KW - Nanostructures KW - Particle Size KW - Principal Component Analysis KW - Silicon Dioxide KW - SOFTWARE KW - Sonication KW - Temperature AB -

BACKGROUND: 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.

RESULTS: 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.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.

CONCLUSION: 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.

VL - 10 U1 - http://www.ncbi.nlm.nih.gov/pubmed/22709926?dopt=Abstract M3 - 10.1186/1477-3155-10-24 ER - TY - BOOK T1 - Analytical challenges and practical solutions for enforcing labeling of nanoingredients in food products in the European Union Y1 - 0 A1 - M Correia A1 - Eveline Verleysen A1 - K. Loeschner KW - analysis KW - electron microscopy KW - Field-flow fractionation KW - food KW - Food Additives KW - Ingredients KW - labeling KW - nanomaterials KW - Nanoparticles KW - Single particle ICP-MS AB - Food ingredients present in the form of engineered nanoparticles (NPs) require specific labeling as “nano” in the European Union. Enforcing proper labeling of “nano” labeling poses several analytical challenges. This includes the many potential sources of NPs in food which can interfere with the analysis, the challenges in relation to sample preparation, the limitations of existing analytical techniques, and the lack of validated studies and reference materials. This book chapter summarizes these challenges and, in addition, suggests a screening strategy for inorganic NPs in food. It further highlights the future challenges of analyzing organic and carbon-based nanomaterials. M3 - https://doi.org/10.1016/B978-0-12-814130-4.00010-5 ER - TY - Generic T1 - Characterization of the TiO2 E171 food additive Y1 - 0 A1 - Frederic Brassinne A1 - Jan Mast ED - Sandra De Vos ED - Eveline Verleysen ED - Pieter-Jan De Temmerman ED - Ledecq, Marina AB -

E171 (Titanium dioxide) is an EC approved food additive (EC 1129/2011), authorized to be used as color in foodstuffs. It is widely used for its refractive properties (shiny coating, UV protection) in the food and pharmaceutical industries. It is intended and assumed to be present in bulk form. A nanofraction may be present.Dispersion is crucial step to characterize the particle properties of food additives as it allows to separate the primary particles. To better characterize titanium dioxide food additives (E171) their dispersion method was optimized.

A dispersion methodology based on the Guiot and Spalla approach was applied. It electrosterically stabilizes the (nano)materials, dispersed by sonication, using BSA at a pH determined by zeta potential measurement. Dispersion efficiency was examined by descriptive TEM and using a combination of TEM imaging and image analysis. The latter approach allows to assess the distribution of the particle properties (size, shape, surface structure) quantitatively. For both the pristine TiO2 food additive E171 and the JRC TiO2 representative test material zeta-potential measurement allowed to identify the conditions (pH) where a stable dispersion with a minimal level of agglomeration was observed. The stability of the dispersion was confirmed by descriptive TEM: preparing dispersions of TiO2 through a pH adjustment provides a stable dispersion of single primary particles and small aggregates and agglomerates.

Under the optimized conditions, the minimal external dimension of the primary particles could be measured more precisely and accurately by a combination of EM imaging and image analysis than in metastable conditions, such that the materials could be better classified according to the EC definition of a nanomaterial.

ER - TY - Generic T1 - Guidance on reporting the results of an EM analysis Y1 - 0 A1 - Jan Mast A1 - Eveline Verleysen ER -