Toxicity and biotransformation of uncoated and coated nickel hydroxide nanoparticles on mesquite plants

Abstract

Nanomaterials are of particular interest in environmental chemistry due to their unknown toxicity to living organisms. Reports indicate that nanoparticles (NPs) affect seed germination, but the uptake and biotransformation of metal nanoparticles is not well understood. The present study investigated the toxicity and biotransformation of Ni(OH)2 NPs by mesquite plants (Prosopis sp.). Three sets of plants were treated for four weeks with 0.01, 0.05, or 0.10 g of either uncoated or sodium citrate coated NPs before and after synthesis. Nickel concentrations in plants were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and the form and oxidation state of Ni was determined using X-ray absorption spectroscopy (XAS). Results showed that uncoated NPs had an average size of 8.7 nm, whereas coated NPs before and after synthesis had an average of 2.5 and 0.9 nm, respectively. The ICP-OES results showed that plants treated with 0.10 g of uncoated and coated NPs before and after synthesis had 803, 764, and 400 mg Ni kg dry weight, in the leaves, respectively. The XAS analyses showed Ni NPs in roots and shoots of plants treated with uncoated NPs, whereas leaves showed a Ni(II)-organic acid type complex. However, plants treated with coated NPs before or after synthesis showed Ni NPs only in roots and a Ni(II)-organic acid complex in shoots and leaves. Results also showed that none of the treatments reduced plant size or chlorophyll production. To the authors' knowledge, this is the first time that the biotransformation of nanoparticles by a plant system is reported.

Bioavailability, Toxicity, and Fate of Manufactured Nanomaterials in Terrestrial Ecosystems

“…However, Barrena et al (2009) reported low or no toxicity after exposing cucumber and lettuce to 10 nm Au and 7 nm Fe 3 O 4 MNMs. Parsons et al (2010) reported that exposure mesquite plants to Ni(OH) 2 MNMs had no effect on biomass production, shoot elongation, or root elongation. Navarro et al (2012) found that Arabidopsis plants produced reduced glutathione relative to oxidized glutathione after exposure to CdSe/ZnS quantum dots, indicating that the MNMs induced oxidative stress in the plants.…”

In Vivo Tracking of Copper-64 Radiolabeled Nanoparticles in Lactuca sativa

“…It is clear from our imaging data, both by autoradiography and PET/CT (Figures 2 and 3) that the 64 Cu]-NPs (11, 20 nm) had a size that appeared smaller than those administered; suggesting that the plant may filter larger NPs and has a size-threshold for uptake ( Figure 6E, F), which may also explain the clogging phenomenon. 27,28,48 In summary, the combined analysis of the imaging by autoradiography and PET/CT (Figures 2 and 3) and TEM ( Figure 6) 45 The amount found in the leaves varied from 400 to 803 μg/g of mesquite with most the NPs remaining in the roots ranging from 12 835 to 38 183 μg/g. 45 Another study using small CeO 2 -NPs (7 nm) exhibited NP accumulation ranging from 300 to 6000 μg/g of plant (corn, soy bean, cucumber, tomato, and alfalfa) and indicated that NP accumulation was plant species dependent.…”

“…The extensive range of NP accumulation reported in plants suggests that NP-uptake is dependent on several parameters: (1) quantity of NP administered per plant, (2) plant species, (3) NP-size, (4) NP-composition, and (5) duration of exposure. 1,12,[14][15][16][17][18]45 Further complicating the understanding of NP transport and accumulation in plants are the studies that have observed NP-uptake due to dissolution. 14,17−19,33−35 Collectively the variations of parameters in every study on NP transport in plants have made direct comparison and accurate conclusions challenging.…”

Interactions between engineered nanomaterials and agricultural crops: implications for food safety

“…Homogeneous dispersions can be achieved by amendment with external surfactants or through the use of surface functionalized ENMs. For example, multi-wall carbon nanotubes (MWCNTs) and C 70 fullerene were stabilized in natural organic matter (NOM, including humic acid) and gum Arabic solutions in the media (Lin et al, 2009;Larue et al, 2012b); metal-based ENMs such as Fe 3 O 4 , Au, Ag, and Ni(OH) 2 were coated with citrate, tannate, or polyvinylpyrrolidone (PVP) (Parsons et al, 2010;Wang H. et al, 2011;Judy et al, 2012a;Lee et al, 2012). There are also reports using agar or semi-solid media such as Murashige and Skoog (MS) medium that may be amended with ENMs prior to solidification (Lee et al, 2008;Miralles et al, 2012b;Yang et al, 2012;Yan et al, 2013).…”

“…In addition, quantum effects become significant with size reduction, subsequently changing particle optical, electrical, and magnetic behaviors. However, great variation exists among different ENMs, including size, shape, physical conformation, specific surface area, surface charge, and the presence of coatings/functionality (Hassellov et al, 2008;Parsons et al, 2010;Pan and Xing, 2012). From the perspective of nanobiological interactions, the most attractive ENMs traits include a high degree of surface reactivity and a size-dependent ability to cross biological membranes.…”