Archives of Toxicology

, Volume 87, Issue 1, pp 99–109 | Cite as

Size of TiO2 nanoparticles influences their phototoxicity: an in vitro investigation

  • Sijing Xiong
  • Saji George
  • Zhaoxia Ji
  • Sijie Lin
  • Haiyang Yu
  • Robert Damoiseaux
  • Bryan France
  • Kee Woei Ng
  • Say Chye Joachim Loo
Inorganic Compounds


To uncover the size influence of TiO2 nanoparticles on their potential toxicity, the cytotoxicity of different-sized TiO2 nanoparticles with and without photoactivation was tested. It was demonstrated that without photoactivation, TiO2 nanoparticles were inert up to 100 μg/ml. On the contrary, with photoactivation, the toxicity of TiO2 nanoparticles significantly increased, which correlated well with the specific surface area of the particles. Our results also suggest that the generation of hydroxyl radicals and reactive oxygen species (ROS)-mediated damage to the surface-adsorbed biomolecules could be the two major reasons for the cytotoxicity of TiO2 nanoparticles after photoactivation. Higher ROS generation from smaller particles was detected under both biotic and abiotic conditions. Smaller particles could adsorb more proteins, which was confirmed by thermogravimetric analysis. To further investigate the influence of the generation of hydroxyl radicals and adsorption of protein, poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan were used to coat TiO2 nanoparticles. The results confirmed that surface coating of TiO2 nanoparticles could reduce such toxicity after photoactivation, by hindering adsorption of biomolecules and generation of hydroxyl radical (·OH) during photoactivation.


Titanium dioxide nanoparticles Phototoxicity Cytotoxicity Nanotoxicity Surface coating 



The authors would like to acknowledge the financial support from the Agency for Science, Technology and Research (A*STAR) (Project No: 102 129 0098), the National Medical Research Council (NMRC/EDG/0062/2009) and the Nanyang Institute of Technology in Health & Medicine (NITHM), Singapore. Acknowledgements to the Ian Ferguson Postgraduate Fellowship for Sijing Xiong’s research attachment at the University of California, Los Angeles (UCLA). We thank Dr. Andre E. Nel and Dr. Tian Xian (UC Center for Environmental Implications of Nanotechnology) for their kind help in enabling this study.

Conflict of interest

The authors have declared no conflict of interest.

Supplementary material

204_2012_912_MOESM1_ESM.tif (127 kb)
Fig.S1 X-ray powder diffraction (XRD) patterns of T10, T20 and T100 nanoparticles. The crystalline phases of different-sized TiO2 nanoparticles were identified by XRD (Panalytical X’Pert Prodiffractometer, CuKα radiation) with a step size of 0.02° and counting time of 0.5 s/step over a range of 20°-80° 2θ. (TIFF 126 kb)
204_2012_912_MOESM2_ESM.tif (115 kb)
Fig.S2 UV − Vis absorption spectra of T20, T20-chitosan and T20-PEMA nanoparticles. The nanoparticles were dispersed in water at a concentration of 50 μg/ml. The UV–Vis absorption spectra were tested by using UV Spectrometer. Both T20-chitosan and T20-PEMA nanoparticles showed decreased UV–Vis absorbance as compared to bare T20 nanoparticles. The T20-PEMA nanoparticles showed more obvious decrease in UV absorbance than T20-chitosan nanoparticles. This could be because more PEMA was attached onto T20 nanoparticles as compared to chitosan, which was proven in TGA studies. (TIFF 114 kb)


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Sijing Xiong
    • 1
  • Saji George
    • 2
    • 3
  • Zhaoxia Ji
    • 2
  • Sijie Lin
    • 2
  • Haiyang Yu
    • 1
  • Robert Damoiseaux
    • 2
  • Bryan France
    • 2
  • Kee Woei Ng
    • 1
  • Say Chye Joachim Loo
    • 1
  1. 1.School of Materials Science and EngineeringNanyang Technological UniversitySingaporeSingapore
  2. 2.California NanoSystems InstituteUniversity of CaliforniaLos AngelesUSA
  3. 3.Centre for Sustainable Nanotechnology, School of Chemical and Life SciencesNanyang PolytechnicSingaporeSingapore

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