Effects of TiO2 nanoparticles on the NO2 − levels in cell culture media analysed by Griess colorimetric methods
The Griess assay has been used to determine the possible changes in the measured NO2 − concentrations induced by TiO2 nanoparticles in three types of nitrite-containing samples: aqueous NaNO2 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 NO2 − by NaNO2 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 Fe3+-doped anatase TiO2) 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), Mössbauer 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 TiO2 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 NO2 − concentrations in the Griess test) depending on the opacity, sedimentation behaviour, NO2 − adsorption and photocatalytic properties of the tested TiO2 nanomaterials. These findings identify material characteristics recommended to be considered when analysing the results of Griess tests performed in biological studies involving TiO2 nanoparticles.
KeywordsGriess assay Nitric oxide production TiO2 nanoparticles Cell activation
This paper is supported by the Sectorial Operational Programme Human Resources Development (SOP HRD), financed from the European Social Fund and by the Romanian Government under the contract number SOP HRD/107/1.5/S/82514 and by the European Social Fund and University of Bucharest, in the frame of the Project POSDRU/89/1.5/S/58852 “Postdoctoral programme for researcher formation in science” (Sectorial Operational Programme for the Development of Human Resources 2007–2013). The support of the Romanian National Authority for Scientific Research, under the Core project PN09-450102, is greatly acknowledged. The authors wish to thank Dr. Dana Culita for the BET experiments.
- Afanas’ev AM, Gorobchenko VD (1974) Shape of Mössbauer spectra in the fast relaxation limit. Zh. Eksp. Teor. Fiz. 66:1406; Report IAE-2215 Moscow 1972Google Scholar
- Barb D, Diamandescu L, Tarabasanu D (1976) On the lineshape of spin relaxation broadened Mössbauer spectra of solid potassium trioxalatoferrate. J Phys C6:113Google Scholar
- Bian K, Harari Y, Zhong M (2001) Down-regulation of inducible nitric-oxide synthase (NOS-2) during parasite-induced gut inflammation: a path to identify a selective NOS-2 inhibitor. Mol Pharmacol 59(4):939–947Google Scholar
- Burdelya L, Kujawski M, Niu G, Zhong B, Wang T, Zhang S, Kortylewski M, Shain K, Kay H, Djeu J, Dalton W, Pardoll D, Wei S, Yu H (2005) Stat3 activity in melanoma cells affects migration of immune effector cells and nitric oxide-mediated antitumor effects. J Immunol 174(7):3925–3931Google Scholar
- Diamandescu L, Vasiliu F, Tarabasanu-Mihaila D, Feder M, Vlaicu AM, Teodorescu CM, Macovei D, Enculescu I, Parvulescu V, Vasile E (2008) Structural and photocatalytic properties of iron-and europium-doped TiO2 nanoparticles obtained under hydrothermal conditions. Mater Chem Phys 112(1):146–153CrossRefGoogle Scholar
- EL-Sharkawy NI, Hamza SM, Abou-Zeid EH (2010) Toxic impact of titanium dioxide (TiO2) in male albino rats with special reference to its effect on reproductive system. J Am Sci 6(11):865–872Google Scholar
- Ko S, Fleming PD, Joyce M, Ari-Gur P (2012) Optical and photocatalytic properties of photoactive paper with polycrystalline TiO2 nanopigment for optimal product design. Tappi J 11(5):33–38Google Scholar
- Othman SH, Rashid SA, Ghazi TIM, Abdullah N (2011) Fe-Doped TiO2 nanoparticles produced via MOCVD: synthesis, characterization, and photocatalytic activity. J Nanomater. doi: 10.1155/2011/571601
- Raja KJA, Shanmugam R, Mahalakshmi R, Viswanathan B (2010) XPS and IR spectral studies on the structure of phosphate and sulphate modified titania-A combined DFT and experimental study. Indian J Chem 49A:9–17Google Scholar
- Suttiponparnit K, Jiang J, Sahu M, Suvachittanont S, Charinpanitkul T, Biswas P (2011) Role of surface area, primary particle size, and crystal phase on titanium dioxide nanoparticle dispersion properties. Nanoscale Res Lett 6:27Google Scholar