Toxicity of aluminium oxide nanoparticles demonstrated using a BY-2 plant cell suspension culture model

Aluminium oxide nanoparticles have been applied in many branches of industry. They are also used in personal care products, such as cosmetics. Because of these uses, their impact on the environment must be considered and investigated. Almost nothing is known about the effects of aluminium oxide nanoparticles on plants at the cellular level; the objective of this work was thus to study the effects of nanoparticles on the plant cell model tobacco BY-2 cell suspension culture, which serves as a model comparable with the HeLa cells used for animal cell studies. We observed the impact of these nanoparticles at different levels. The inhibitory effect on growth was observed in both time- and concentration-dependent studies. In addition, the ability of the nanoparticles to generate reactive oxygen (hydrogen peroxide, superoxide anion radical) and nitrogen species (nitric oxide) has been established. The principal part of the work was focused on the ability of aluminium oxide nanoparticles to induce the processes of programmed cell death. Changes observed in the permeability of the plasma membrane are connected with the effects of the reactive oxygen species and lipid peroxidation. In addition, the loss of mitochondrial potential, the enhancement of the caspase-like activity and the fragmentation of DNA determined in both time- and concentration dependent studies are closely connected with the execution of the programmed cell death. Our results indicate the ability of aluminium oxide nanoparticles to induce programmed cell death in plant cells and may explain the toxic effect of these nanoparticles on plants.