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Characterization of TiO2 nanoparticles as food additive
William Dudefoi, Hélène Terrisse, Mireille Richard-Plouet, Bernard Humbert,
E. Gautron, Marie-Hélène Ropers
To cite this version:
William Dudefoi, Hélène Terrisse, Mireille Richard-Plouet, Bernard Humbert, E. Gautron, et al.. Characterization of TiO2 nanoparticles as food additive. 11. International Conference on the Envi-ronmental Effects of Nanoparticles and Nanomaterials (ICEENN 2016), Aug 2016, Golden, United States. 2016. �hal-02740390�
CHARACTERIZATION OF TiO
2NANOPARTICLES AS FOOD
ADDITIVE
W. Dudefoi , H. Terrisse1 2, M. Richard-Plouet2, B. Humbert2, E. Gautron2, M-H. Ropers1,*
1INRA, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France 2Institut des Matériaux Jean Rouxel IMN, Université de Nantes, CNRS, 44322 Nantes
*e-mail: marie-helene.ropers@nantes.inra.fr
Titanium dioxide (TiO2) is a white metal oxide commonly used as a white pigment in various applications such as paints, cosmetic but also food products where it constitutes the coating of sweets and chewing-gum. Due to the classification of TiO2 nanoparticles as potentially harmful for humans by inhalation, the toxicity after ingestion raised concerns and needs to be evaluated. However, the physicochemical characteristics of food grade TiO2 are poorly known.
In this study, we studied several food grade TiO2 samples (size distribution, shape, crystallinity, reactivity, surface properties) and evaluated whether they are similar to the well-known P25 particles that served as reference for numerous toxicological studies.
The main result of our study is that E171 and P25 are different particles, with different compositions and surface chemistry. TEM analysis confirmed the presence of nanoparticles in P25 and in E171 samples, but the primary sizes and the percentage of nano-sized particles were different: 23 nm with 100% of nanoparticles in P25 and 131 nm with 26% of nanoparticles in E171. Isoelectric points were assessed by zeta potential measurements and were determined at pH 6.2 for P25 and between pH 2 and pH 4.2 for E171 depending on suppliers. Particle size distribution analyses showed different agglomeration behavior: E171 tended to form larger agglomerates at pH < 5 whereas P25 formed larger agglomerates at pH > 5. XRD, XPS, FT-RAMAN, DRIFTS, surface specific area analysis and ICP-AES analysis showed P25 particles are a mixture 75/25 of rutile/anatase with a pure and reactive surface, whereas E171 is a 100% anatase, coated with some organic impurities, and sometimes silicon and aluminum. Finally, this work confirms the recent paper of Yang et al., 2014 (Environ. Si. Tech. 2014, 48, 6391) and provides some more data on food grade TiO2 surface chemistry including specific surface area and DRIFTS measurements but also size distribution evolution from pH 1 to pH 9. Some variability was also found among food grade TiO2 samples, leading us to strongly recommend researchers to properly characterize their samples before each of their toxicological studies. In any case, using Degussa P25 particles does not appear to be the most reliable model to study the fate of food grade TiO2 in the gastro-intestinal tract.
Acknowledgements
This work has been carried out in the framework of the Labex Serenade (ANR-11-LABX-0064) and of the A*MIDEX project (ANR-11-IDEX-0001-02), funded by the «Investissements d’Avenir» French Government program managed by the French National Research Agency (ANR).
