Functional Analysis of TiO sub(2) Nanoparticle Toxicity in Three Plant Species

• Published in: Biological trace element research 2013-10, Vol.155 (1), p.93-103
• Main Authors: Song, Uhram, Shin, Minjoo, Lee, Gisuk, Roh, Jinkyu, Kim, Younghun, Lee, Eun Ju
• Format: Article
• Language: English
• ISSN: 0163-4984; 1559-0720
• DOI: 10.1007/s12011-013-9765-x

Titanium dioxide nanoparticles (nano-TiO sub(2)) are manufactured and used worldwide in large quantities. However, phytotoxicity research on nano-TiO sub(2) has yielded confusing results, ranging from strong toxicity to positive effects. Therefore, in this research, the effects of nano-TiO sub(2) on the germination and root elongation of seed and seedlings were studied. Additionally, the uptake and physiological responses of mature plants were investigated. Physical chemistry data were analyzed to assess the availability of nano-TiO sub(2). Finally, a hydroponic system designed to overcome nano-TiO sub(2) precipitation was used to reproduce the environmental conditions of actual fields. Nano-TiO sub(2) did not have any effect on seed germination or on most of the plant species tested. Nano-TiO sub(2) had positive effects on root elongation in some species. No physiological differences in enzyme activities or chlorophyll content were detected, even though the plants absorbed nano-TiO sub(2). Physical chemistry data showed that nano-TiO sub(2) agglomerated rapidly and formed particles with much bigger hydrodynamic diameters, even in distilled water and especially in a hydroponic system. Furthermore, agglomerated nano-TiO sub(2) formed precipitates; this would be more severe in an actual field. Consequently, nano-TiO sub(2) would not be also readily available to plants and would not cause any significant effects on plants. Our results and other reports suggest that titanium itself is not phytotoxic, even though plants absorb titanium. In conclusion, nano-TiO sub(2) is not toxic to the three plant species, in vitro or in situ.