Toxic effects of copper-based nanoparticles or compounds to lettuce (Lactuca sativa) and alfalfa (Medicago sativa)

Abstract

The increased production and use of nanoparticles (NPs) has generated concerns about their impact on living organisms. In this study, nCu, bulk Cu, nCuO, bulk CuO, Cu(OH)2 (CuPRO 2005, Kocide 3000), and CuCl2 were exposed for 15 days to 10 day-old hydroponically grown lettuce (Lactuca sativa) and alfalfa (Medicago sativa). Each compound was applied at 0, 5, 10, and 20 mg/L. At harvest, we measured the size of the plants and determined the concentration of Cu, macro and microelements by using ICP-OES. Catalase and ascorbate peroxidase activity was also determined. Results showed that all Cu NPs/compounds reduced the root length by 49% in both plant species. All Cu NPs/compounds increased Cu, P, and S (>100%, >50%, and >20%, respectively) in alfalfa shoots and decreased P and Fe in lettuce shoot (>50% and >50%, respectively, excluding Fe in CuCl2 treatment). Biochemical assays showed reduced catalase activity in alfalfa (root and shoot) and increased ascorbate peroxidase activity in roots of both plant species. Results suggest that Cu NPs/compounds not only reduced the size of the plants but altered nutrient content and enzyme activity in both plant species.

Comparative environmental fate and toxicity of copper nanomaterials

“…All Cu particles and dissolved Cu 2 + significantly (p < 0.05) reduced root length in both plant species at ≥5 mg/L (Hong et al, 2014). Exposure to 20 mg/L nCuO or nCu resulted in the shortest root lengths in both plants.…”

“…mussels) that pack and excrete Cu (ion and NPs) in pseudofeces (Hanna et al, 2013;Montes et al, 2012), in fish (Abdel-Khalek et al, 2016), marine invertebrates , and in terrestrial plants (Hong et al, 2014;Zhao et al, 2016a;Zhao et al, 2016b;Zhao et al, 2016c). While it is likely that Cu is internalized as Cu 2 + or in organic complexes, in some cases Cu NPs are ingested or taken up from soil into the organisms, where they likely dissolve.…”

“…soil vs. hydroponics). For example, for lettuces (Hong et al, 2014), alfalfa (Hong et al, 2014) and cilantro (Zuverza-Mena et al, 2015) exposed via soil, uptake of nCu, nCuO, and the two nCu(OH) 2 nanopesticides resulted in accumulation of Cu mostly (> 87% and some cases > 99%) in the roots, with little translocation to the stems, and almost none to leaves (Fig. 2).…”

“…Lettuce (Lactuca sativa) and alfalfa (Medicago sativa) grown in hydroponic media were exposed for 15 d, after 10 d of germination, to the six particles (nCu, nCuO, nCu(OH) 2 -a, nCu(OH) 2 -b, μCu and μCuO) and CuCl 2 at Cu concentrations from 0 to 20 mg/L (Hong et al, 2014). All Cu particles and dissolved Cu 2 + significantly (p < 0.05) reduced root length in both plant species at ≥5 mg/L (Hong et al, 2014).…”

Heteroaggregation of nanoparticles with biocolloids and geocolloids

“…The application of ENMs has raised concern over the safety of these materials to human health and the ecosystem [2,14,17]. Several studies have shown that ENMs can have effects on aquatic and terrestrial organisms at certain exposure thresholds [25][26][27][28][29][30]. The release of CNT into the environment might also result in negative effects and thus causes concern [30].…”