Evaluation of genotoxicity and oxidative stress of aluminium oxide nanoparticles and its bulk form in Allium cepa

Staggering cytotoxic effects of manganese oxide nanoparticles from Bacillus thuringiensis

The current study describes the biological synthesis of manganese oxide nanoparticles from Bacillus thuringiensis, as well as their characterization, biological activity, and toxicity. Nanoparticles may be synthesized in multiple ways, but the biogenic process is the most environmentally friendly and cost-effective. The optical, structural, and crystalline properties of the nanoparticles were investigated. A distinctive peak at 246 nm with a band gap of 3.7eV indicates manganese oxide nanoparticle production. A strong peak at 563.09 cm-1 indicates Mn-O stretching in Fourier Transform Infrared Spectroscopy analysis. X-ray diffraction revealed that the crystalline grain size of manganese oxide nanoparticles was 11.23 nm. The agglomerated spherical shape is seen in the Scanning Electron Microscope and High-Resolution Transmission Electron Microscope investigations. The presence of manganese was verified by the EDAX. Manganese oxide nanoparticles have a significant zeta potential peak of -23.4 mV. This work explored the biological activity of manganese oxide nanoparticles, including antibacterial, anti-inflammatory, antioxidant, and biofilm inhibition studies. To investigate cytotoxicity, Allium cepa root tips are treated with manganese oxide nanoparticles.

In vitro cytotoxicity evaluation of green synthesized alumina nanoscales on different mammalian cell lines

Nanoscale research is gaining interest in the biomedical, engineering, and environmental fields. Current expensive traditional chemical methods for synthesizing nanoparticles (NPs) inevitably lead to the synthesis of NPs with potentially less or no toxic effects on living cells. To overcome these challenges, in this study, we use a simple, inexpensive, and less toxic one-pot green chemistry approach instead of a chemical method to synthesize alumina nanoparticles (AlNPs) from Carica papaya extract. Nano-alumina has been widely studied due to its remarkable biological and physiochemical properties at nanoscale. However, to date, its biomedical application is limited due to the lack of sufficient data on cytotoxicity in living cells. The physicochemical properties of nano-alumina were determined by FT-IR, DLS, SEM and HRTEM. The cytotoxic effects of the synthesized nano-alumina were studied in cell lines LT and VERO at concentrations of 10-480 µg/mL in vitro. The cell viability of nano-alumina was evaluated using the MTT assay and the AO /EB double staining technique. Our results based on DLS and HRTEM analyzes confirmed spherical AlNPs with a zeta potential and average particle size of - 25 to 5 mV and 52 nm, respectively. The nano-alumina tested showed low toxicity to both cell lines after 28- and 48-h exposure. Furthermore, cell viability statistically decreased with increasing incubation time and concentration of AlNPs up to 480 μg/mL (p < 0.001). However, a minimal increase in cytotoxicity was observed at threshold levels in the range of 120-480 µg/mL. The half-maximal inhibitory concentration (IC50) of AlNPs in the VERO and LT cell lines were 153.3, 252.0 µg/mL and 186.6, 395.3 µg/mL, respectively, after 24- and 48-h exposure to AlNPs. Thus, we conclude that the cytotoxic effect of AlNPs depends on the concentration, exposure time and cell type. The result suggests that the concentration used in this study may be useful for biomedical applications.

The Allium cepa comet assay for environmental sample assessment: a scoping review

The purposes of this review were to investigate the application of the comet assay in Allium cepa root cells to assess the genotoxicity of environmental samples and to analyse the experimental procedures employed. A literature search was performed selecting articles published between January 2000 and October 2023 from online databases using the combined search terms 'comet assay' and 'A. cepa'. Only 18 papers met the inclusion criteria. None of these were published in the first eight years (2000-2007), highlighting the increasing interest in using the comet assay on A. cepa to analyse environmental samples over the last decade. The majority of the selected studies (15/18, 83%) were performed on samples belonging to the water compartment on onion bulbs. Half of the selected studies (9/18) were conducted to demonstrate the DNA damaging effect of the sample, while the other half of the studies not only recognized the presence of genotoxic agents but also addressed possible remediation measures. Detailed analysis of the experimental procedures revealed heterogeneity in many key steps, such as exposure time, test controls, nuclei isolation solutions, duration of electrophoresis, and number of nuclei scored. This literature review has shown that the comet assay on A. cepa, although recognized as an appropriate tool, is underutilized in environmental toxicology. Greater standardization could lead to its more widespread use, providing valuable information on the genotoxicity of environmental samples and the ability of different processes to mitigate their negative effects on plants.

A scoping review of recent advances in the application of comet assay to Allium cepa roots

The comet assay is a sensitive method for the evaluation of DNA damages and DNA repair capacity at single-cell level. Allium cepa is a well-established plant model for toxicological studies. The aim of this scoping review was to investigate the recent application of the comet assay in Allium cepa root cells to assess the genotoxicity. To explore the literature a search was performed selecting articles published between January 2015 and February 2023 from Web of Science, PubMed, and Scopus databases using the combined search terms "Comet assay" and "Allium cepa". All the original articles that applied the comet assay to Allium cepa root cells were included. Of the 334 records initially found, 79 articles were identified as meeting the inclusion criteria. Some studies reported results for two or more toxicants. In these cases, the data for each toxicant were treated separately. Thus, the number of analyzed toxicants (such as chemicals, new materials, and environmental matrices) was higher than the number of selected papers and reached 90. The current use of the Allium-comet assay seems to be directed towards two types of approach: the direct study of the genotoxicity of compounds, mainly biocides (20% of analyzed compounds) and nano- and microparticles (17%), and assessing a treatment's ability to reduce or eliminate genotoxicity of known genotoxicants (19%). Although the genotoxicity identified by the Allium-comet assay is only one piece of a larger puzzle, this method could be considered a useful tool for screening the genotoxic potential of compounds released into the environment.

Nanoparticle-based toxicity in perishable vegetable crops: Molecular insights, impact on human health and mitigation strategies for sustainable cultivation

With the advancement of nanotechnology, the use of nanoparticles (NPs) and nanomaterials (NMs) in agriculture including perishable vegetable crops cultivation has been increased significantly. NPs/NMs positively affect plant growth and development, seed germination, plant stress management, and postharvest handling of fruits and vegetables. However, these NPs sometimes cause toxicity in plants by oxidative stress and excess reactive oxygen species production that affect cellular biomolecules resulting in imbalanced biological and metabolic processes in plants. Therefore, information about the mechanism underlying interactions of NPs with plants is important for the understanding of various physiological and biochemical responses of plants, evaluating phytotoxicity, and developing mitigation strategies for vegetable crops cultivation. To address this, recent morpho-physiological, biochemical and molecular insights of nanotoxicity in the vegetable crops have been discussed in this review. Further, factors affecting the nanotoxicity in vegetables and mitigation strategies for sustainable cultivation have been reviewed. Moreover, the bioaccumulation and biomagnification of NPs and associated phytotoxicity can cause serious effects on human health which has also been summarized. The review also highlights the use of advanced omics approaches and interdisciplinary tools for understanding the nanotoxicity and their possible use for mitigating phytotoxicity.

A comprehensive review of impacts of diverse nanoparticles on growth, development and physiological adjustments in plants under changing environment

The application of nanotechnology in agriculture includes the use of nanofertilizers, nanopesticides, and nanoherbicides that enhance plant nutrition without disturbing the soil texture and protect it against microbial infections. Thus, nanotechnology maintains the plant's health by maintaining its soil health. The use of nanoparticles (NPs) in agriculture reduces the chemical spread and nutrient loss and boosts crop yield and productivity. Effect of NPs varies with their applied concentrations, physiochemical properties, and plant species. Various NPs have an impact on the plant to increase biomass productivity, germination rate and their physiology. Also, NPs change the plant molecular mechanisms by altering gene expression. Metal and non-metal oxides of NPs (Au, Ag, ZnO, Fe₂O₃, TiO₂, SiO₂, Al₂O₃, Se, carbon nanotubes, quantum dots) exert an important role in plant growth and development and perform an essential role in stress amelioration. On the other hand, other effects of NPs have also been well investigated by observing their role in growth suppression and inhibition of chlorophyll and photosynthetic efficiency. In this review, we addressed a description of studies that have been made to understand the effects of various kind of NPs, their translocation and interaction with the plants. Also, the phytoremediation approaches of contaminated soil with combined use of NPs for sustainable agriculture is covered.

Cytotoxic and genotoxic evaluation of copper oxychloride through Allium test and molecular docking studies

Copper oxychloride gained great importance due to its broad-spectrum antifungal action to combat various fungal diseases of plants. However, excess quantity of cupric fungicides on plants causes enzymatic changes and toxic effects. Thus, the current study was aimed to investigate the cytotoxicity and genotoxicity of copper oxychloride on Allium cepa root cells. The root growth, mitotic index (MI), chromosomal aberrations (CAs), and DNA damage were assessed through root growth inhibition, A. cepa ana-telophase, and alkaline comet assays. Furthermore, molecular docking was performed to evaluate binding affinities of two copper oxychloride polymorphs (atacamite and paratacamite) on DNA. In root growth inhibition test, onion root length was statistically significantly decreased by changing the copper oxychloride concentration from lower (2.64±0.11 cm) to higher (0.92±0.12 cm). Concentration- and time-dependent decrease in MI was observed whereas increase in CAs such as disturbed ana-telophase, chromosome laggards, stickiness, anaphase bridges, and DNA damage were caused by the copper oxychloride on A. cepa root cells. Molecular docking results revealed that the two main polymorphs of copper oxychloride (atacamite and paratacamite) bind selectively to G and C nucleotides on the B-DNA structure. It is concluded that the atacamite- and paratacamite-induced DNA damage may be through minor groove recognition and intercalation. Findings of the current study revealed the cytotoxic and genotoxic effects of copper oxychloride on A. cepa root cells. However, further studies should be carried out at the molecular level to reveal the cyto-genotoxic mechanism of action of copper oxychloride in detail.

Responses of Medicinal and Aromatic Plants to Engineered Nanoparticles

Medicinal and aromatic plants have been used by mankind since ancient times. This is primarily due to their healing effects associated with their specific secondary metabolites (some of which are also used as drugs in modern medicine), or their structures, served as a basis for the development of new effective synthetic drugs. One way to increase the production of these secondary metabolites is to use nanoparticles that act as elicitors. However, depending on the specific particle size, composition, concentration, and route of application, nanoparticles may have several other benefits on medicinal and aromatic plants (e.g., increased plant growth, improved photosynthesis, and overall performance). On the other hand, particularly at applications of high concentrations, they are able to damage plants mechanically, adversely affect morphological and biochemical characteristics of plants, and show cytotoxic and genotoxic effects. This paper provides a comprehensive overview of the beneficial and adverse effects of metal-, metalloid-, and carbon-based nanoparticles on the germination, growth, and biochemical characteristics of a wide range of medicinal and aromatic plants, including the corresponding mechanisms of action. The positive impact of nanopriming and application of nanosized fertilizers on medicinal and aromatic plants is emphasized. Special attention is paid to the effects of various nanoparticles on the production of valuable secondary metabolites in these plants cultivated in hydroponic systems, soil, hairy root, or in vitro cultures. The beneficial impact of nanoparticles on the alleviation of abiotic stresses in medicinal and aromatic plants is also discussed.

Effect of AuNPs and AgNPs on the Antioxidant System and Antioxidant Activity of Lavender (Lavandula angustifolia Mill.) from In Vitro Cultures

The aim of this study was to determine the effect of gold and silver nanoparticles on the activity of antioxidant enzymes (ascorbate peroxidase (APX), superoxide dismutase (SOD), guaiacol peroxidase (POX), and catalase (CAT)), the free radical scavenging capacity, and the total polyphenol capacity of lavender (Lavandula angustifolia Mill.) cultivar “Munstead” propagated in vitro. In the experiment, fragments of lavender plants were cultivated in vitro on medium with the addition of 1, 2, 5, 10, 20, and 50 mg∙dm⁻³ of AgNPs or AuNPs (particle sizes 24.2 ± 2.4 and 27.5 ± 4.8 nm, respectively). It was found that the nanoparticles increase the activity of the antioxidant enzymes APX and SOD; however, the reaction depends on the NP concentration. The highest APX activity is found in plants propagated on media with 2 and 5 mg∙dm⁻³ of AgNPs. AuNPs significantly increase the APX activity when added to media with a concentration of 10 mg∙dm⁻³. The highest SOD activity is recorded at 2 and 5 mg∙dm⁻³ AgNP and AuNP concentrations. The addition of higher concentrations of nanoparticles to culture media results in a decrease in the APX and SOD activity. The addition of AuNPs to culture media at concentrations from 2 to 50 mg∙dm⁻³ increases the POX activity in comparison to its activity when AgNPs are added to the culture media. No significant influence of NPs on the increase in CAT activity was demonstrated. AgNPs and AuNPs increased the free radical scavenging capacity (ABTS^•+). The addition of NPs at concentrations of 2 and 5 mg∙dm⁻³ increased the production of polyphenols; however, in lower concentrations it decreased their content in lavender tissues.

Nanoparticles in Agroindustry: Applications, Toxicity, Challenges, and Trends

Nanotechnology is a tool that in the last decade has demonstrated multiple applications in several sectors, including agroindustry. There has been an advance in the development of nanoparticulated systems to be used as fertilizers, pesticides, herbicides, sensors, and quality stimulants, among other applications. The nanoencapsulation process not only protects the active ingredient but also can affect the diffusion, interaction, and activity. It is important to evaluate the negative aspects of the use of nanoparticles (NPs) in agriculture. Given the high impact of the nanoparticulated systems in the agro-industrial field, this review aims to address the effects of various nanomaterials on the morphology, metabolomics, and genetic modification of several crops.

Cytotoxic and Genotoxic Assessment of Silicon Dioxide Nanoparticles by Allium and Comet Tests

Silicon nanoparticles gained a great interest due to its use in biomedical research. It is considered as safe and has been used in nanomedicine. But literature still states its toxicity depending upon the size and dose of silicon nanoparticles. So, current study was aimed to evaluate the cytotoxicity and genotoxicity of silicon dioxide nanoparticles (SiO₂NPs) by Allium anaphase-telophase and Comet tests. Characterization of SiO₂NPs showed the particle size as 16.12 ± 3.07 nm. The mean diameter of SiO₂NPs was having range of 404.66 ± 93.39 nm in solution. Highest total anomalies (18.80 ± 0.45) were observed at 100 µg/mL, whereas least (11.2 ± 0.84) were observed by the 12.5 µg/mL concentration. There was concentration-response association in increased CAs and DNA damage. The highest concentration (100 µg/mL) of SiO₂NPs induced the significant DNA damage (149.67 ± 1.15), whereas the least was observed by the negative control (2.67 ± 0.58). The current study revealed the cytotoxic and genotoxic effects of SiO₂NPs on the root meristem cells of A. cepa.

Cytotoxicity and genotoxicity of cerium oxide micro and nanoparticles by Allium and Comet tests

Cerium oxide (CeO₂) is extensively used in a range of applications like in television tubes, glass/ceramic polishing agent, fuel cells, solar cells, gas sensor andultraviolet absorbents. In current study, Allium ana-telophase and comet assays were employed to evaluate the cytotoxic and genotoxic effects of CeO₂ microparticles (CMPs, <5 µm, bulk) and CeO₂ nanoparticles (CNPs, < 25 nm) on the root meristem cells of Allium cepa by using mitotic phases, mitotic index (MI), chromosomal aberrations (CAs), and DNA damage. A cepa roots were treated with the CMPs and CNPs at four different concentrations (12.5, 25, 50, and 100 ppm) for 4 h. Methyl methane sulphonate (MMS,10 ppm) and distilled water were used as positive and negative control groups, respectively. All the applied doses statistically decreased MIs. MI values of CMPs were found higher than CNPs. CMPs and CNPs significantly increased CAs such as chromosome laggards, disturbed anaphase-telophase, stickiness and bridges and also DNA damage. Characterization of CMPs and CNPs showed the particle size as 4.24 ± 0.7 µm and 20.28 ± 2.33 nm, respectively. The average diameter of CMPs and CNPs in solution were in the range of 372.75 ± 70.23 nm and 167.74 ± 38.7 nm, respectively. These results demonstrated that CMPs and CNPs had cytotoxic and genotoxic effects in A. cepa root meristematic cells.

Engineered nanomaterials for plant growth and development: A perspective analysis

With the overwhelmingly rapid advancement in the field of nanotechnology, the engineered nanomaterials (ENMs) have been extensively used in various areas of the plant system, including quality improvement, growth and nutritional value enhancement, gene preservation etc. There are several recent reports on the ENMs' influence on growth enhancements, growth inhibition as well as certain toxic impacts on plant. However, translocation, growth responses and stress modulation mechanisms of ENMs in the plant systems call for better and in-depth understanding. Herein, we are presenting a comprehensive and critical account of different types of ENMs, their applications and their positive, negative and null impacts on physiological and molecular aspects of plant growth, development and stress responses. Recent reports revealed mixed effects on plants, ranging from enhanced crop yield, epi/genetic alterations, and phytotoxicity, resulting from the ENMs' exposure. Creditable research in recent years has revealed that the effects of ENMs on plants are species specific and are variable among plant species. ENM exposures are reported to trigger free radical formation, responsive scavenging, and antioxidant armories in the exposed plants. The ENMs are also reported to induce aberrant expressions of microRNAs, the key post-transcriptional regulators of plant growth, development and stress-responses of plants. However, these modulations, if judiciously done, may lead to improved plant growth and yield. A better understanding of the interactions between ENMs and plant responses, including their uptake transport, internalization, and activity, could revolutionize crop production through increased disease resistance, nutrient utilization, and crop yield. Therefore, in this review, we are presenting a critical account of the different selected ENMs, their uptake by the plants, their positive/negative impacts on plant growth and development, along with the resultant ENM-responsive post-transcriptional modifications, especially, aberrant miRNA expressions. In addition, underlying mechanisms of various ENM-plant cell interactions have been discussed.

Chromosomal aberrations, cell suppression and oxidative stress generation induced by metal oxide nanoparticles in onion (Allium cepa) bulb

In this work, we assess the phytotoxicity of various-sized metal oxide nanoparticles on cell cycle progression and induction of oxidative stress in onions.

In planta genotoxicity of nZVI: influence of colloidal stability on uptake, DNA damage, oxidative stress and cell death

Nanoremediation of soil, ground and surface water using nanoscale zerovalent iron particles (nZVI) has facilitated their direct environmental exposure posing ecotoxicological concerns. Numerous studies elucidate their phytotoxicity in terms of growth and their fate within the plant system. However, their potential genotoxicity and cytotoxicity mechanisms are not known in plants. This study encompasses the physico-chemical characterisation of two forms of nZVI (nZVI-1 and nZVI-2) with different surface chemistries and their influence on uptake, root morphology, DNA damage, oxidative stress and cell death in Allium cepa roots after 24 h. To our knowledge, this is the first report on the cyto-genotoxicity of nZVI in plants. The adsorption of nZVI on root surfaces caused root tip, epidermal and root hair damage as assessed by Scanning Electron Microscopy. nZVI-1, due to its colloidal destabilisation (low zeta potential, conductivity and high polydispersity index), smaller size and high uptake imparted enhanced DNA damage, chromosome/nuclear aberrations (CAs/NAs) and micronuclei formation compared to nZVI-2. Although nZVI-2 exhibited high zeta potential and conductivity, its higher dissolution and substantial uptake induced genotoxicity. nZVI incited the generation of reactive oxygen species (ROS) (hydrogen peroxide, superoxide and hydroxyl radicals) leading to membrane lipid peroxidation, electrolyte leakage and mitochondrial depolarisation. The inactivation of catalase and insignificant glutathione levels marked the onset of oxidative stress. Increased superoxide dismutase and guaiacol peroxidase enzyme activities, and proline content indicated the activation of antioxidant defence machinery to alleviate ROS. Moreover, ROS-mediated apoptotic and necrotic cell death occurred in both nZVI-1 and nZVI-2-treated roots. Our results open up further possibilities in the environmental safety appraisal of bare and modified nZVI in correlation with their physico-chemical characters.