Abstract
Engineered nanoscale materials (ENMs) are considered emerging contaminants since they are perceived as a potential threat to the environment and the human health. The reactions of living organisms when exposed to metal nanoparticles (NPs) or NPs of different size are not well known. Very few studies on NPs–plant interactions have been published, so far. For this reason there is also great concern regarding the potential NPs impact to food safety. Early genotoxic and phytotoxic effects of cerium oxide NPs (nCeO2) and titanium dioxide NPs (nTiO2) were investigated in seedlings of Hordeum vulgare L. Caryopses were exposed to an aqueous dispersion of nCeO2 and nTiO2 at, respectively 0, 500, 1000, and 2000 mg l-1 for 7 days. Genotoxicity was studied by Randomly Amplified Polymorphism DNA (RAPDs) and mitotic index on root tip cells. Differences between treated and control plants were observed in RAPD banding patterns as well as at the chromosomal level with a reduction of cell divisions. At cellular level we monitored the oxidative stress of treated plants in terms of reactive oxygen species (ROS) generation and ATP content. Again nCeO2 influenced clearly these two physiological parameters, while nTiO2 were ineffective. In particular, the dose 500 mg l-1 showed the highest increase regarding both ROS generation and ATP content; the phenomenon were detectable, at different extent, both at root and shoot level. Total Ce and Ti concentration in seedlings was detected by ICP-OES. TEM EDSX microanalysis demonstrated the presence of aggregates of nCeO2 and nTiO2 within root cells of barley. nCeO2 induced modifications in the chromatin aggregation mode in the nuclei of both root and shoot cells.
Highlights
It is estimated that by 2020 about six million people will be employed worldwide in industries that use nanotechnologies, which will have the potential to produce goods for a market of more than 3,000 billion dollars (Roco, 2011)
Cerium oxide nanoparticles (NPs; nCeO2) and titanium oxide NPs are among the top ten most produced engineered nanomaterials (ENMs) by mass (Keller et al, 2013) and used in cosmetics industries, in solar cells, paints, cements, coatings, in agriculture and the food industry (Gogos et al, 2012; Piccinno et al, 2012; Parisi et al, 2015). nCeO2 and nTiO2 were included in the list of ENMs of priority for immediate testing by the Organization for Economic Cooperation and Development (OECD, 2010)
The suspensions were characterized for Z-average size, measured as hydrodynamic diameter, zeta potential, via electrophoretic mobility, and polydispersity index (PDI), calculated from the signal intensity, by the dynamic light scattering (DLS) method using the Nano ZS90 (Malvern Instruments, UK)
Summary
It is estimated that by 2020 about six million people will be employed worldwide in industries that use nanotechnologies, which will have the potential to produce goods for a market of more than 3,000 billion dollars (Roco, 2011). Cerium oxide nanoparticles (NPs; nCeO2) and titanium oxide NPs (nTiO2) are among the top ten most produced ENMs by mass (Keller et al, 2013) and used in cosmetics industries, in solar cells, paints, cements, coatings, in agriculture and the food industry (Gogos et al, 2012; Piccinno et al, 2012; Parisi et al, 2015). NCeO2 and nTiO2 were included in the list of ENMs of priority for immediate testing by the Organization for Economic Cooperation and Development (OECD, 2010). Clément et al (2013) reported similar results for nTiO2 on rapeseed plantlets treated with 14–25 nm particles. Another functional property that influences the MeNPs plant assimilation is the agglomeration/aggregation status that in turn is influenced directly by the zeta-potential (Navarro et al, 2008).
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