Multiple method analysis of TiO2 nanoparticles uptake, accumulation and effects in rice (Oryza sativa L.) plants
Yinqging Deng, Elijah J. Petersen, Katie Challis, Savelas A. Rabb, Richard D. Holbrook, James Ranville, Bryant C. Nelson, Baoshan Xing
Understanding the translocation of nanoparticles (NPs) into plants is challenging because quantitative and qualitative methods are still being developed and the comparability of results among different methods is unclear. In this study, the uptake of NPs and larger bulk particles (BPs) in plant tissues was evaluated using three orthogonal techniques: electron microscopy, single-particle inductively coupled plasma mass spectroscopy (spICP-MS) with two different plant digestion approaches, and total elemental analysis using ICP optical emission spectroscopy. Through a chronic TiO2 NP and BP exposure with rice (Oryza sativa L.) plants at 5 mg/L and 50 mg/L and a total elemental analysis, we here report that TiO2 NPs penetrated into the plant root and resulted in Ti accumulation in aboveground tissues at a significantly higher level compared to BPs. Through both acid and enzymatic digestions coupled with spICP-MS, the size distribution of internalized TiO2 NPs in the rice tissues was reported and distinguished from the BPs. In addition to uptake and accumulation, the TiO2 NP treatments were found to significantly enhance the rice vegetative growth beginning at the 4th week, revealing that the long-term effect of TiO2 NPs exposure on plant growth may not be foreseen through tests in seedling stages.