Effects of TiO sub(2) nanoparticles on the NO sub(2) super(-) levels in cell culture media analysed by Griess colorimetric methods

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2013-02, Vol.15 (2), p.1-17
• Main Authors: Popescu, Traian, Lupu, Andreea R, Diamandescu, Lucian, Tarabasanu-Mihaila, Doina, Teodorescu, Valentin S, Raditoiu, Valentin, Purcar, Violeta, Vlaicu, Aurel M
• Format: Article
• Language: English
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-013-1449-0

The Griess assay has been used to determine the possible changes in the measured NO sub(2) super(-) concentrations induced by TiO sub(2) nanoparticles in three types of nitrite-containing samples: aqueous NaNO sub(2) solutions with known concentrations, and two types of cell culture media-Roswell Park Memorial Institute medium (RPMI-1640) and Dulbecco's Modified Eagle Medium (DMEM-F12) used either as delivered or enriched in NO sub(2) super(-) by NaNO sub(2) addition. We have used three types of titania with average particle sizes between 10 and 30 nm: Degussa P25 and two other samples (undoped and Fe super(3+)-doped anatase TiO sub(2)) synthesised by a hydrothermal route in our laboratory. The structural, morphological, optical and physicochemical characteristics of the used materials have been studied by X-ray diffraction, transmission electron microscopy (EDX), Mossbauer spectroscopy, Brunauer-Emmett-Teller nitrogen adsorption, UV-Vis reflectance spectroscopy, dynamic light scattering and diffuse reflectance infrared Fourier transform spectroscopy. The opacity and sedimentation behaviour of the studied TiO sub(2) suspensions have been investigated by photometric attenuance measurements at 540 nm. To account for the photocatalytic properties of titania in a biologically relevant context, multiple Griess tests have been performed under controlled exposure to laboratory natural daylight illumination. The results show significant variations of light attenuance (associated with NO sub(2) super(-) concentrations in the Griess test) depending on the opacity, sedimentation behaviour, NO sub(2) super(-) adsorption and photocatalytic properties of the tested TiO sub(2) nanomaterials. These findings identify material characteristics recommended to be considered when analysing the results of Griess tests performed in biological studies involving TiO sub(2) nanoparticles.