Abstract
BackgroundDespite manifold benefits of nanoparticles (NPs), less information on the risks of NPs to human health and environment has been studied. Cobalt oxide nanoparticles (Co3O4-NPs) have been reported to cause toxicity in several organisms. In this study, we have investigated the role of Co3O4-NPs in inducing phytotoxicity, cellular DNA damage and apoptosis in eggplant (Solanum melongena L. cv. Violetta lunga 2). To the best of our knowledge, this is the first report on Co3O4-NPs showing phytotoxicity in eggplant.ResultsThe data revealed that eggplant seeds treated with Co3O4-NPs for 2 h at a concentration of 1.0 mg/ml retarded root length by 81.5 % upon 7 days incubation in a moist chamber. Ultrastructural analysis by transmission electron microscopy (TEM) demonstrated the uptake and translocation of Co3O4-NPs into the cytoplasm. Intracellular presence of Co3O4-NPs triggered subcellular changes such as degeneration of mitochondrial cristae, abundance of peroxisomes and excessive vacuolization. Flow cytometric analysis of Co3O4-NPs (1.0 mg/ml) treated root protoplasts revealed 157, 282 and 178 % increase in reactive oxygen species (ROS), membrane potential (ΔΨm) and nitric oxide (NO), respectively. Besides, the esterase activity in treated protoplasts was also found compromised. About 2.4-fold greater level of DNA damage, as compared to untreated control was observed in Comet assay, and 73.2 % of Co3O4-NPs treated cells appeared apoptotic in flow cytometry based cell cycle analysis.ConclusionThis study demonstrate the phytotoxic potential of Co3O4-NPs in terms of reduction in seed germination, root growth, greater level of DNA and mitochondrial damage, oxidative stress and cell death in eggplant. The data generated from this study will provide a strong background to draw attention on Co3O4-NPs environmental hazards to vegetable crops.
Highlights
Despite manifold benefits of nanoparticles (NPs), less information on the risks of NPs to human health and environment has been studied
Since no systematic study has been attempted so far, describing the mechanism of Co3O4-NPs induced phytotoxicity in eggplant at cellular and molecular levels, we have investigated the effect of Co3O4-NPs on eggplant cells to assess the (1) phytotoxicity, (2) translocation of Co3O4-NPs in root cells and subcellular anomalies, (3) intracellular reactive oxygen species (ROS) generation and mitochondrial dysfunction (ΔΨm), (4) DNA damage (5) cell cycle alterations, nitric oxide (NO) generation and esterase activity
Co3O4‐NPs characterization Size and morphology of Co3O4-NPs were examined by transmission electron microscopy (TEM) and atomic force microscope (AFM) analyses
Summary
Despite manifold benefits of nanoparticles (NPs), less information on the risks of NPs to human health and environment has been studied. Cobalt oxide nanoparticles (Co3O4-NPs) have been reported to cause toxicity in several organisms. We have investigated the role of Co3O4-NPs in inducing phytotoxicity, cellular DNA damage and apoptosis in eggplant To the best of our knowledge, this is the first report on Co3O4-NPs showing phytotoxicity in eggplant. The uptake and translocation of TiO2NPs in Allium cepa induces heavy ROS generation, sticky, multipolar and laggard chromosomes, including micronucleus formation and DNA damage [6]. These effects of NPs are primarily associated with their increased surface area and reactivity, ROS generation and the tendency to form agglomerates [4]. The composites of Co3O4-NPs with multiwalled carbon nanotubes have been proposed for fabricating high-performance electronic devices [8]
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