Phytoremediation of engineered nanoparticles using aquatic plants: Mechanisms and practical feasibility

Phytoremediation of nanoparticles, as future water pollutants, using aquatic and wetland plants: Feasibility, benefits and risks, and research gaps

The widespread use of nanoparticles (NPs) in recent years and their rapid accumulation as potentially dangerous pollutants can lead to significant environmental risks. Different methods are used to eliminate emerging contaminants such as NPs from aquatic environments. Of these methods, phytoremediation using aquatic and wetland plants (WAPs) is considered the most suitable approach because of their extensive root systems, high rates of biomass production, ability to thrive in diverse habitats, and rapid growth within aquatic ecosystems. Various species of genera Lemna, Salvinia, Spirodela, Phragmites, Elodea, and Pistia have been studied for their potential to remediate NPs or contaminants released by NPs. The findings of the review indicate that the majority of WAPs cannot accumulate NPs within their tissues. Nevertheless, the effective methods for removing NPs from the environment by WAPs involve the surface adsorption of NPs onto their roots and the accumulation of pollutants released by NPs within the plant tissues. In addition to the benefits of NPs phytoremediation through WAPs, including sustainability, efficiency, and affordability, there are risks to consider, such as the potential transfer of NPs into the food chain, the release of toxic compounds from NPs due to (bio)degradation, and interactions between contaminated WAPs and other ecosystem components. Furthermore, several research gaps need to be addressed in the future, including a scarcity of field studies, a limited focus on NP types and plant species, unrealistic NP concentration, comparisons with bulk materials, the use of additives and amendments, and the genetic engineering of WAPs.

Exploiting the synergistic influence of AgNPs-TiO2NPs: enhancing phytostabilization of Pb and mitigating its toxicity in Vigna unguiculata

In this study, a composite of silver and titanium dioxide nanoparticles (AgNPs-TiO2NPs) was examined for its synergistic effects on phytostabilization of lead (Pb) and mitigation of toxicity in cowpea (Vigna unguiculata (L) Walp). Seeds of V. unguiculata were wetted with water, 0.05 and 0.1 mgL-1 Pb and 25 mgmL-1 each of AgNPs, TiO2NPs, and AgNPs-TiO2NPs. Root lengths of V. unguiculata were reduced by 25% and 44% at 0.05 and 0.1 mgL-1 Pb, respectively, while shoot lengths were reduced by 2% and 7%. In V. unguiculata, AgNPs and TiO2NPs significantly improved physiological indicators and mitigated Pb effects, with TiO2NPs modulating physiological parameters more effectively than AgNPs. The composite (AgNPs-TiO2NPs) synergistically regulated V. unguiculata physiology better than individual nanoparticles. Compared to individual AgNPs and TiO2NPs, the composite (AgNPs-TiO2NPs) synergistically increased antioxidant activity by 12% and 9%, and carotenoid contents by 88%. Additionally, AgNPs-TiO2NPs effectively reduced malondialdehyde levels by 29%, thereby mitigating the effects of Pb on V. unguiculata better than individual nanoparticles. AgNPs-TiO2NPs enhanced Pb immobilization by 57%, reducing its translocation from soil to shoots compared to V. unguiculata wetted with water. The bioconcentration and translocation factors of Pb indicate that phytostabilization was most effective when the composite was used.

Influence of light-emitting diodes (LEDs) on the 2,4-diclorophenoxyacetic acid phytoremediation by plectranthus neochilus

2,4-Dichlorophenoxyacetic acid (2,4-D) is an herbicide widely used in crops against broadleaf weeds. However, 2,4-D residues are considered an environmental pollutant in bodies of water. Phytoremediation with Plectranthus neochilus is a substantial strategy to remove 2,4-D from the aquatic environment. The objective of this study was to verify the efficiency of the association of the photostimulus by Light Emitting Diodes (LED) with P. neochilus to improve phytoremediation of 2,4-D in water. Phytoremediation was evaluated with the following samples: natural light, white LED, blue LED, and red LED, with and without the plant as controls. The data corresponding to the validation of the method were in accordance with the required parameters: R2: 0.9926; RSD: 1.74%; LOD: 0.075 mg.L-1; LOQ: 0.227 mg.L-1 and recovery by SPE was 76.57%. The efficiency of the association of LED with P. neochilus in the 28 days was: ambient light + plant (47.0%); white light + plant (37.10%); blue light + plant (26.80%); red light + plant (3.32%). This study demonstrated, for the first time, the efficiency of using LEDs light in association with P. neochilus for the phytoremediation of 2,4-D in water.

Sorption capacity of Eichhornia crassipes (Mart.) Solms for zinc removal from electroplating industry wastewater

Various industrial operations in the dye, fertilizer, pesticide, battery, mining, and chemical industries have been associated with releasing heavy metals in wastewater, such as lead, zinc, copper, arsenic, cadmium, chromium, nickel, and mercury. These metals are dangerous to aquatic life as well as to humans, who may consume them directly or indirectly. Therefore, before being released into open water and land resources, it is necessary to minimize the concentration of toxic ions below the discharge limit. This study used Eichhornia crassipes (Mart.) Solms to remove zinc from wastewater from the electroplating industry in a constructed wetland. Experimental investigations were conducted for removing zinc ions from electroplating industry wastewater using various process parameters such as nutrient dosages, dilution ratios, potential of hydrogen ions, biomasses, and contact times. The outcome of this study revealed that the maximum zinc removal percentage in electroplating industrial wastewater was found for the optimum nutrient dosages of 60 g, dilution ratios of 10, potential hydrogen ion levels of 8, and biomass amounts of 100 g. The maximum zinc removal by Eichhornia crassipes (Mart.) Solms was found to be 88.3 ± 0.6 and 93.4 ± 0.4% at the optimum parameter values for the electroplating industry wastewater and the aqueous solution, respectively, against the optimum contact time of 22 days. This study suggests using this phytoremediation technology to remove all pollutants from industrial wastewater in general, not just wastewater from the electroplating industry.

Silver nanoparticles in plant health: Physiological response to phytotoxicity and oxidative stress

Silver nanoparticles (AgNPs) have gained significant attention in various fields due to their unique properties, but their release into the environment has raised concerns about their environmental and biological impacts. Silver nanoparticles can enter plants following their exposure to roots or via stomata following foliar exposure. Upon penetrating the plant cells, AgNPs interact with cellular components and alter physiological and biochemical processes. One of the key concerns associated with plant exposure to AgNPs is the potential of these materials to induce oxidative stress. Silver nanoparticles can also suppress plant growth and development by disrupting essential plant physiological processes, such as photosynthesis, nutrient uptake, water transport, and hormonal regulation. In crop plants, these disruptions may, in turn, affect the productivity and quality of the harvested components and therefore represent a potential threat to agricultural productivity and ecosystem stability. Understanding the phytotoxic effects of AgNPs is crucial for assessing their environmental implications and guiding the development of safe nanomaterials. By delving into the phytotoxic effects of AgNPs, this review contributes to the existing knowledge regarding their environmental risks and promotes the advancement of sustainable nanotechnological practices.

Subchronic toxicity of iron-selenium nanoparticles on oxidative stress response, histopathological, and nuclear damage in amphibian larvae Rana saharica

In this work, we evaluated the subchronic toxicity of FeSe nanoparticles (NPs) in tadpoles of Rana saharica. Tadpoles were exposed for 1-3 weeks to FeSe NPs at 5 mg/L and 100 mg/L rates. Parameters of oxidative stress were measured in whole larvae, and the micronucleus test was performed on circulating blood erythrocytes. We noted a disturbance of the detoxification systems. Enzymatic and non-enzymatic data showed that exposure to FeSe NPs involved a highly significant depletion of GSH, a significant increase in GST activity, and a lipid peroxidation associated with a highly significant increase in MDA. We also noted a neurotoxic effect characterized by a significant inhibition of AChE activity. A micronucleus test showed concentration-dependent DNA damage. This research reveals that these trace elements, in their nanoform, can cause significant neurotoxicity, histopathologic degeneration, cellular and metabolic activity, and genotoxic consequences in Rana larvae.

Insight interactions of engineered nanoparticles with aquatic higher plants for phytoaccumulation, phytotoxicity, and phytoremediation applications: A review

With the growing age of human civilization, industrialization has paced up equally which is followed by the innovation of newer concepts of science and technology. One such example is the invention of engineered nanoparticles and their flagrant use in widespread applications. While ENPs serve their intended purposes, they also disrupt the ecological balance by contaminating pristine aquatic ecosystems. This review encompasses a comprehensive discussion about the potent toxicity of ENPs on aquatic ecosystems, with a particular focus on their impact on aquatic higher plants. The discussion extends to elucidating the fate of ENPs upon release into aquatic environments, covering aspects ranging from morphological and physiological effects to molecular-level phytotoxicity. Furthermore, this level of toxicity has been correlated with the determination of competent plants for the phytoremediation process towards the mitigation of this ecological stress. However, this review further illustrates the path of future research which is yet to be explored. Determination of the genotoxicity level of aquatic higher plants could explain the entire process comprehensively. Moreover, to make it suitable to be used in natural ecosystems phytoremediation potential of co-existing plant species along with the presence of different ENPs need to be evaluated. This literature will undoubtedly offer readers a comprehensive understanding of the stress induced by the irresponsible release of engineered nanoparticles (ENP) into aquatic environments, along with insights into the resilience characteristics of these pristine ecosystems.

Biochar applications for treating potentially toxic elements (PTEs) contaminated soils and water: a review

Environmental pollution with potentially toxic elements (PTEs) has become one of the critical and pressing issues worldwide. Although these pollutants occur naturally in the environment, their concentrations are continuously increasing, probably as a consequence of anthropic activities. They are very toxic even at very low concentrations and hence cause undesirable ecological impacts. Thus, the cleanup of polluted soils and water has become an obligation to ensure the safe handling of the available natural resources. Several remediation technologies can be followed to attain successful remediation, i.e., chemical, physical, and biological procedures; yet many of these techniques are expensive and/or may have negative impacts on the surroundings. Recycling agricultural wastes still represents the most promising economical, safe, and successful approach to achieving a healthy and sustainable environment. Briefly, biochar acts as an efficient biosorbent for many PTEs in soils and waters. Furthermore, biochar can considerably reduce concentrations of herbicides in solutions. This review article explains the main reasons for the increasing levels of potentially toxic elements in the environment and their negative impacts on the ecosystem. Moreover, it briefly describes the advantages and disadvantages of using conventional methods for soil and water remediation then clarifies the reasons for using biochar in the clean-up practice of polluted soils and waters, either solely or in combination with other methods such as phytoremediation and soil washing technologies to attain more efficient remediation protocols for the removal of some PTEs, e.g., Cr and As from soils and water.

Silver nanoparticles strengthen Zea mays against toxic metal-related phytotoxicity via enhanced metal phytostabilization and improved antioxidant responses

This study investigated the phytostabilization and plant-promoting abilities of silver nanoparticles (AgNPs). Twelve Zea mays seeds were planted in water and AgNPs (10, 15 and 20 mg mL-1) irrigated soil for 21 days on soil containing 0.32 ± 0.01, 3.77 ± 0.03, 3.64 ± 0.02, 69.91 ± 9.44 and 13.17 ± 0.11 mg kg-1 of As, Cr, Pb, Mn and Cu, respectively. In soil treated with AgNPs, the metal contents were reduced by 75%, 69%, 62%, 86%, and 76%. The different AgNPs concentrations significantly reduced accumulation of As, Cr, Pb, Mn, and Cu in Z. mays roots by 80%, 40%, 79%, 57%, and 70%, respectively. There were also reductions in shoots by 100%, 76%, 85%, 64%, and 80%. Translocation factor, bio-extraction factor and bioconcentration factor demonstrated a phytoremediation mechanism based on phytostabilization. Shoots, roots, and vigor index improved by 4%, 16%, and 9%, respectively in Z. mays grown with AgNPs. Also, AgNPs increased antioxidant activity, carotenoids, chlorophyll a and chlorophyll b by 9%, 56%, 64%, and 63%, respectively, while decreasing malondialdehyde contents in Z. mays by 35.67%. This study discovered that AgNPs improved the phytostabilization of toxic metals while also contributing to Z. mays' health-promoting properties.

Transcriptome analysis reveals the molecular mechanisms of Phragmites australis tolerance to CuO-nanoparticles and/or flood stress induced by arbuscular mycorrhizal fungi

The molecular mechanism of arbuscular mycorrhizal fungi (AMF) in vertical flow constructed wetlands (VFCWs) for the purification of copper oxide nanoparticles (CuO-NPs) contaminated wastewater remains unclear. In this study, transcriptome analysis was used to explore the effect of AMF inoculation on the gene expression profile of Phragmites australis roots under different concentrations of CuO-NPs and/or flood stress. 551, 429 and 2281 differentially expressed genes (DEGs) were specially regulated by AMF under combined stresses of CuO-NPs and flood, single CuO-NPs stress and single flood stress, respectively. Based on the results of DEG function annotation and enrichment analyses, AMF inoculation under CuO-NPs and/or flood stress up-regulated the expression of a number of genes involved in antioxidant defense systems, cell wall biosynthesis and transporter protein, which may contribute to plant tolerance. The expression of 30 transcription factors (TFs) was up-regulated by AMF inoculation under combined stresses of CuO-NPs and flood, and 44 and 44 TFs were up-regulated under single CuO-NPs or flood condition, respectively, which may contribute to the alleviating effect of symbiosis on CuO-NPs and/or flood stress. These results provided a theoretical basis for enhancing the ecological restoration function of wetland plants for metallic nanoparticles (MNPs) by mycorrhizal technology in the future.

Isolation, Identification and Pollution Prevention of Bacteria and Fungi during the Tissue Culture of Dwarf Hygro (Hygrophila polysperma) Explants

Microbial contamination causes serious damage in plant tissue culture, and attention is always being paid regarding how to control and prevent the unwanted pollution. Dwarf hygro (Hygrophila polysperma) is a popular ornamental aquatic plant and its tissue culture has been reported, but the microbial pollution and the cure of microbial pollution was unknown. In this study, a number of bacteria and fungi were isolated from contaminants in MS culture media. Based on the 16S rDNA and ITS sequencing, it was identified that fifteen bacteria belong to Bacillus, Enterobacter, Pantoea, Kosakonia, Ensifer and Klebsiella, and three fungi belong to Plectosphaerella, Cladosporium and Peniophora, respectively. In addition, some drugs were further tested to be free of the bacteria and fungi pollution. The results revealed that 10 μg/mL of kanamycin, 5 μg/mL of chloramphenicol, and 0.015625% potassium sorbate could be applied jointly in MS media to prevent the microbial pollution, and the survival rate of H. polysperma explants was highly improved. This study reveals the bacteria and fungi species from the culture pollution of H. polysperma and provides a practical reference for optimizing the tissue culture media for other aquatic plants.

Application of zinc oxide nanoparticles to promote remediation of nickel by Sorghum bicolor: metal ecotoxic potency and plant response

Nickel (Ni) is one of the most toxic metals in human health. Its bioaccumulation in gluten-free crops limits the progressing demand of safe foods for allergic people to gluten. Nanoparticles have shown promising results in enhancing the crop yield and reducing the risk of heavy metal uptake. However, their nanotoxicity has been raised environmental concerns. This study investigated the environmental behavior of Ni (II) with the co-presence of Zinc Oxide Nanoparticles (ZnO-NPs) in sorghum bicolor. The plants were exposed to different treatments of Ni, ZnO-NPs, or their coexistence. The uptake experiments were carried out within nine treatments consisting of 1 or 5 ppm Ni alone or in coexistence with 50 or 100 ppm ZnO-NPs. The physiological impacts on plants as potential fingerprints for nanotoxicity were recorded and assessed in a phenotypic spectrum. The total Ni or Zn contents were quantified using atomic absorption. NPs significantly altered the bioavailability of Ni. The results revealed that at 5 ppm Ni contamination, 50 and 100 ZnO-NPs significantly reduced the Ni uptake by ∼43% and 47%, respectively. Further, the results showed at 50 ppm NPs, the phytotoxicity effects of both Ni and NPs may reduce, leading to higher plant dry biomass yield.Novelty statement Characterization of zinc oxide nanotoxicity threshold by developing a phenotypic spectrum. Also, the study revealed the phytoremediation potential of ZnO nanoparticle in mitigating the nickel uptake in a gluten-free crop (sorghum bicolor).

Evaluation of Metal-Organic Framework MIL-89 nanoparticles toxicity on embryonic zebrafish development

Metal-Organic Framework MIL-89 nanoparticles garnered remarkable attention for their widespread use in technological applications. However, the impact of these nanomaterials on human and environmental health is still limited, and concerns regarding the potential risk of exposure during manipulation is constantly rising. Therefore, the extensive use of nanomaterials in the medical field necessitates a comprehensive assessment of their safety and interaction with different tissues of the body system. In this study, we evaluated the systemic toxicity of nanoMIL-89 using Zebrafish embryos as a model system to determine the acute developmental effect. Zebrafish embryos were exposed to a range of nanoMIL-89 concentrations (1 - 300 µM) at 4 h post-fertilization (hpf) for up to 120 hpf. The viability and hatching rate were evaluated at 24-72 hpf, whereas the cardiac function was assessed at 72 and 96 hpf, and the neurodevelopment and hepatic steatosis at 120 hpf. Our study shows that nanoMIL-89 exerted no developmental toxicity on zebrafish embryos at low concentrations (1-10 µM). However, the hatching time and heart development were affected at high concentrations of nanoMIL-89 (> 30 µM). Our findings add novel information into the available data about the in vivo toxicity of nanoMIL-89 and demonstrate its innocuity and safe use in biological, environmental, and medical applications.

Environmental Consequences of Rubber Crumb Application: Soil and Water Pollution

End-of-life tires are utilized for various purposes, including sports pitches and playground surfaces. However, several substances used at the manufacture of tires can be a source of concerns related to human health or environment’s adverse effects. In this context, it is necessary to map whether this approach has the desired effect in a broader relation. While the negative effects on human health were investigated thoroughly and legislation is currently being revisited, the impact on aquatic or soil organisms has not been sufficiently studied. The present study deals with the exposure of freshwater and soil organisms to rubber crumb using the analysis of heavy metal and polycyclic aromatic hydrocarbon concentrations. The obtained results refer to substantial concerns related to freshwater contamination specifically, since the increased concentrations of zinc (7 mg·L⁻¹) and polycyclic aromatic hydrocarbons (58 mg·kg⁻¹) inhibit the growth of freshwater organisms, Desmodesmus subspicatus, and Lemna minor in particular. The performed test with soil organisms points to substantial concerns associated with the mortality of earthworms as well. The acquired knowledge can be perceived as a roadmap to a consistent approach in the implementation of the circular economy, which brings with it a number of so far insufficiently described problems.

Recent advances in nanoremediation: Carving sustainable solution to clean-up polluted agriculture soils

Agriculture is one of the foremost significant human activities, which symbolizes the key source for food, fuel and fibers. This activity results in a lot of ecological harms particularly with the excessive usage of chemical fertilizers and pesticides. Different agricultural practices have remained industrialized to advance food production, due to the growth in the world population and to meet the food demand through the routine use of more effective fertilizers and pesticides. Soil is intensely embellished by environmental contamination and it can be stated as "universal incline." Soil pollution usually occurs from sewage wastes, accidental discharges or as byproducts of chemical residues of unrestrained production of numerous materials. Soil pollution with hazardous materials alters the physical, chemical, and biological properties, causing undesirable changes in soil fertility and ecosystem. Engineered nanomaterials offer various solutions for remediation of contaminated soils. Engineered nanomaterial-enable technologies are able to prevent the uncontrolled release of harmful materials into the environment along with capabilities to combat soil and groundwater borne pollutants. Currently, nanobiotechnology signifies a hopeful attitude to advance agronomic production and remediate polluted soils. Studies have outlined the way of nanomaterial applications to restore the eminence of the environment and assist the detection of polluted sites, along with potential remedies. This review focuses on the latest developments in agricultural nanobiotechnology and the tools developed to combat soil or land and or terrestrial pollution, as well as the benefits of using these tools to increase soil fertility and reduce potential toxicity.

Nano-biotechnology, an applicable approach for sustainable future

Nanotechnology is one of the most emerging fields of research within recent decades and is based upon the exploitation of nano-sized materials (e.g., nanoparticles, nanotubes, nanomembranes, nanowires, nanofibers and so on) in various operational fields. Nanomaterials have multiple advantages, including high stability, target selectivity, and plasticity. Diverse biotic (e.g., Capsid of viruses and algae) and abiotic (e.g., Carbon, silver, gold and etc.) materials can be utilized in the synthesis process of nanomaterials. "Nanobiotechnology" is the combination of nanotechnology and biotechnology disciplines. Nano-based approaches are developed to improve the traditional biotechnological methods and overcome their limitations, such as the side effects caused by conventional therapies. Several studies have reported that nanobiotechnology has remarkably enhanced the efficiency of various techniques, including drug delivery, water and soil remediation, and enzymatic processes. In this review, techniques that benefit the most from nano-biotechnological approaches, are categorized into four major fields: medical, industrial, agricultural, and environmental.

Critical review of the characteristics, interactions, and toxicity of micro/nanomaterials pollutants in aquatic environments

A wide range of contaminants of emerging concern such as micro/nanoplastics (MPs/PNPs) and metal-nanoparticles (Me-NPs) from anthropogenic activities have been identified in aquatic environments. The hazardous effects of these micro/nanomaterials as pollutants in organisms and the lack of knowledge about their behavior in aquatic environments have generated growing concern in the scientific community. The nanomaterials have a colloidal-type behavior due to their size range but with differences in their physicochemical properties. This review comprises the behavior of micro/nanomaterials pollutants and the physicochemical interactions between MPs/PNPs and Me-NPs in aquatic environments, and their potential toxicological effects in organisms. Moreover, this article describes the potential use of Me-NPs to remove MPs/PNPs present in the water column due to their photocatalytic and magnetic properties. It also discusses the challenge to determine harmful effects of micro/nanomaterials pollutants in organisms and provides future research directions to improve integrated management strategies to mitigate their environmental impact.

Recent advances in responses of arbuscular mycorrhizal fungi - Plant symbiosis to engineered nanoparticles

The application of engineered nanomaterials (ENMs) is increasing in all walks of life, inevitably resulting in a high risk of ENMs entering the natural environment. Recent studies have demonstrated that phytoaccumulation of ENMs in the environment may be detrimental to plants to varying degrees. However, plants primarily assimilate ENMs through the roots, which are inevitably affected by rhizomicroorganisms. In this review, we focus on a group of common rhizomicroorganisms-arbuscular mycorrhizal fungi (AMF). These fungi contribute to ENMs immobilization and inhibition of phytoaccumulation, improvement of host plant growth and activation of systematic protection in response to excess ENMs stress. In present review, we summarize the biological responses of plants to ENMs and the modulatory mechanisms of AMF on the immobilization of ENMs in substrate-plant interfaces, and indirectly regulatory mechanisms of AMF on the deleterious effects of ENMs on host plants. In addition, the information of feedback of ENMs on mycorrhizal symbiosis and the prospects of future research on the fate and mechanism of phyto-toxicity of ENMs mediated by AMF in the environment are also addressed. In view of above, synergistic reaction of plants and AMF may prove to be a cost-effective and eco-friendly technology to bio-control potential ENMs contamination on a sustainable basis.

Efficacy of Lemna minor and Typha latifolia for the treatment of textile industry wastewater in a constructed wetland under citric acid amendment: A lab scale study

Lead (Pb), copper (Cu) and chromium (Cr) are one of the most harmful heavy metals (HMs), entering into the food chain through the irrigation of crops with an industrial effluent. The present study was performed to evaluate the toxic effects of textile effluents and performance of citric acid (CA) on phytoextraction potential of Lemna minor L. and Typha latifolia L. in an artificially designed wetland. Different doses of textile wastewater (0, 25, 50, 75, and 100%) and CA (10 mM) were applied alone and in combination. Plants were harvested and the data was collected regarding agronomic traits, photosynthetic pigments, antioxidant enzymes, reactive oxygen species (ROS), electrolytic leakage (EL) and HMs uptake and accumulation. The results depicted that the concentration and accumulation of Cu, Pb and Cr in different parts of T. latifolia plant was increased with and without CA addition. The maximum concentration of Pb, Cu and Cr increased in leaves by 279, 240 & 171%, in stem by 192, 172 & 154%, and in roots by 224, 183 & 168%, respectively. Similarly, the accumulation of Pb, Cu and Cr increased in leaves by 91, 71 & 36%, in stem by 57, 46 & 36% and in roots by 76, 53 & 45%, respectively in plants treated with 100% textile effluent as compared to the 25% textile effluent treated plants under CA amendment. In L. minor, the concentration of Pb, Cu & Cr increased by 542, 411 and 397% while accumulation increased by 101, 59 & 55% respectively in overall plant biomass.

Nano-biofortification of different crops to immune against COVID-19: A review

Human health and its improvement are the main target of several studies related to medical, agricultural and industrial sciences. The human health is the primary conclusion of many studies. The improving of human health may include supplying the people with enough and safe nutrients against malnutrition to fight against multiple diseases like COVID-19. Biofortification is a process by which the edible plants can be enriched with essential nutrients for human health against malnutrition. After the great success of biofortification approach in the human struggle against malnutrition, a new biotechnological tool in enriching the crops with essential nutrients in the form of nanoparticles to supplement human diet with balanced diet is called nano-biofortification. Nano biofortification can be achieved by applying the nano particles of essential nutrients (e.g., Cu, Fe, Se and Zn) foliar or their nano-fertilizers in soils or waters. Not all essential nutrients for human nutrition can be biofortified in the nano-form using all edible plants but there are several obstacles prevent this approach. These stumbling blocks are increased due to COVID-19 and its problems including the global trade, global breakdown between countries, and global crisis of food production. The main target of this review was to evaluate the nano-biofortification process and its using against malnutrition as a new approach in the era of COVID-19. This review also opens many questions, which are needed to be answered like is nano-biofortification a promising solution against malnutrition? Is COVID-19 will increase the global crisis of malnutrition? What is the best method of applied nano-nutrients to achieve nano-biofortification? What are the challenges of nano-biofortification during and post of the COVID-19?

In search for potential biomarkers of copper stress in aquatic plants

Over the last few decades, the use of pesticides and discharge of industrial and domestic wastewater on water surfaces have increased. Especially, Copper (Cu) pollution in aquatic ecosystems could constitute a major health problem, not only for flora and fauna but also for humans. To cope with this challenge, environmental monitoring studies have sought to find Cu-specific biomarkers in terrestrial and aquatic flora and/or fauna. This review discusses the toxic effects caused by Cu on the growth and development of plants, with a special focus on aquatic plants. While copper is considered as an essential metal involved in vital mechanisms for plants, when in excess it becomes toxic and causes alterations on biomarkers: biochemical (oxidative stress, pigment content, phytochelatins, polyamines), physiological (photosynthesis, respiration, osmotic potential), and morphological. In addition, Cu has a detrimental effect on DNA and hormonal balance. An overview of Cu toxicity and detoxification in plants is provided, along with information regarding Cu bioaccumulation and transport. Awareness of the potential use of these reactions as specific biomarkers for copper contamination has indeed become essential.

Exposure of cerium oxide nanoparticles to the hyperaccumulator Sedum alfredii decreases the uptake of cadmium via the apoplastic pathway

Cadmium (Cd) is harmful to the environment and threatens human health. With the increasing use of cerium oxide nanoparticles (CeO₂NPs) in extensive industries, investigating the combination of CeO₂NPs and plants has attracted research interests for phytoremediation. Here, we explored the effects of CeO₂NPs on Cd uptake, transport and the consequent Cd accumulation in Sedum alfredii. Exposure of 50 or 500 mg L^-1 CeO₂NPs alone had no apparent damaging effects on plant growth. However, upon Cd condition, the consistent CeO₂NPs decreased Cd concentrations in the roots and shoots by up to 37%. Furthermore, the application of a metabolic inhibitor revealed that CeO₂NPs mainly decreased the Cd uptake in roots by the apoplastic pathway. Simultaneously, CeO₂NPs accelerated the development of Casparian strips (CSs) and suberin, which was further proven by the elevated expression levels of genes associated with their formation, SaCASP, SaGPAT5, SaKCS20 and SaCYP86A1. Compared to CeO₂NPs added alone, the concurrent Cd decreased the Ce contents in the roots and altered its translocation from root to shoot. Taken together, both CeO₂NPs and Cd influence the interactional uptake of both chemicals in roots of S. alfredii mainly via the apoplastic pathway which is primarily regulated by the development of CSs and suberin.

In silico nanosafety assessment tools and their ecosystem-level integration prospect

Engineered nanomaterials (ENMs) have tremendous potential in many fields, but their applications and commercialization are difficult to widely implement due to their safety concerns. Recently, in silico nanosafety assessment has become an important and necessary tool to realize the safer-by-design strategy of ENMs and at the same time to reduce animal tests and exposure experiments. Here, in silico nanosafety assessment tools are classified into three categories according to their methodologies and objectives, including (i) data-driven prediction for acute toxicity, (ii) fate modeling for environmental pollution, and (iii) nano-biological interaction modeling for long-term biological effects. Released ENMs may cross environmental boundaries and undergo a variety of transformations in biological and environmental media. Therefore, the potential impacts of ENMs must be assessed from a multimedia perspective and with integrated approaches considering environmental and biological effects. Ecosystems with biodiversity and an abiotic environment may be used as an excellent integration platform to assess the community- and ecosystem-level nanosafety. In this review, the advances and challenges of in silico nanosafety assessment tools are carefully discussed. Furthermore, their integration at the ecosystem level may provide more comprehensive and reliable nanosafety assessment by establishing a site-specific interactive system among ENMs, abiotic environment, and biological communities.

Type-specific impacts of silver on the protein profile of tomato (Lycopersicon esculentum L.)

Silver nanoparticles (AgNPs) are particularly among the widely used nanomaterials in medicine, industry, and agriculture. The small size and large surface area of AgNPs and other nanomaterials result in their high reactivity in biological systems. To better understand the effects of AgNPs on plants at the molecular level, tomato (Lycopersicon esculentum L.) seedlings were exposed to 30 mg/L silver in the form of nanoparticle (AgNPs), ionic (AgNO₃), or bulk (Ag⁰) in 50% Hoagland media for 7 days. The effects of silver on the expression of plant membrane transporters H⁺-ATPase, vacuolar type H⁺-ATPase (V-ATPase), and enzymes isocitrate dehydrogenase (IDH), and catalase in roots was assessed using RT-qPCR and immunofluorescence-confocal microscopy. We observed significantly higher expression of catalase in plants exposed to AgNPs (Fold of expression 1.1) and AgNO₃ (Fold of expression 1.2) than the control group. The immunofluorescence imaging of the proteins confirmed the gene expression data; the expression of the enzyme catalase was upregulated 41, 216, and 770% higher than the control group in plants exposed to AgNPs, Ag⁰, and AgNO₃, respectively. Exposure to AgnO₃ resulted in the upregulation (fold of expression 1.2) of H⁺-ATPase and downregulation (fold of expression 0.7) of V-ATPase. A significant reduction in the expression of the redox-sensitive tricarboxylic cycle (TCA) enzyme mitochondrial IDH was observed in plants exposed to AgNPs (38%), AgNO₃ (48%), or Ag⁰ (77%) compared to the control. This study shows that exposure to silver affects the expression of genes and protein involved in membrane transportation and oxidative response. The ionic form of silver had the most significant effect on the expression of genes and proteins compared to other forms of silver. The results from this study improve our understanding about the molecular effects of different forms of silver on important crop species. Novelty statementSilver nanoparticles released into the environment can be oxidized and be transformed into ionic form. Both the particulate and ionic forms of silver can be taken by plants and affect plants physiological and molecular responses. Despite the extensive research in this area, there is a scarce of information about the effects of silver nanoparticles on the expression of membrane transporters especially H⁺-ATPase involved in regulating cells' electrochemical charge, and the activity of enzymes involved in oxidative stress responses. This is a unique study that evaluates the expression of cellular proton transporters and enzymes of redox balance and energy metabolisms such as membrane transporters, H⁺-ATPase, and V-ATPases, and enzymes catalase and IDH. The results provide us valuable information about the impact of silver on plants at the molecular level by evaluating the expression of genes and proteins. Key MessageThe exposure of plants to silver as an environmental stressor affects the expression of genes and proteins involved in maintaining cell's electrochemical gradient (H⁺-ATPase, V-ATPase) and redox potential (IDH, catalase).

Effects of hydrophyte decomposition on the binding mechanism between fluorescent DOM and copper

Hydrophyte decomposition caused large amounts of dissolved organic matter (DOM) to enter aquatic environment that influence the migration and transformation of heavy metals (HMs). Six hydrophytes with five dry weight gradients (DWG) were used for the decomposition experiments. The results showed that protein-like materials occupy relatively high content in the hydrophyte-derived DOM. The binding properties of DOM-Cu(II) have been explored by using two-dimensional correlation spectroscopy (2D-COS) in conjunction with synchronous fluorescence spectroscopy (SFS) and log-transformed SFS. The weak signals of binding site can be amplified by the log-transformed 2D-COS analysis. Herein, more binding sites can be identified by the log-transformed 2D-COS analysis. The results reveal that tryptophan-like materials show a preferential sequence of binding Cu(II) in the hydrophyte-derived DOM with a relatively low DWG and sediment DOM, and fulvic-like substances indicate a preferential sequence of binding Cu(II) in the hydrophyte-derived DOM with a relatively high DWG. Meanwhile, the results of binding parameters indicate that the log K is the range of 3.61-4.25, 4.33-4.74, 4.59-4.97, 3.91-4.41, and 4.14-4.78 for D1-D5, respectively, suggesting that hydrophyte decomposition can change the binding affinity between DOM components and Cu(II). The complexes of fluorescent components with Cu(II) showed a high log K value at long wavelength (e.g. humic-like substances), and a relatively low fluorescent ligand proportion (f%) at shorter wavelength in the hydrophyte-derived DOM. However, the log K is the range of 3.08-4.31, 4.09-4.45, 3.93-4.35, 4.39-4.75, and 3.95-4.36 for C1-C5, separately. Protein-like substances with Cu(II) showed a relatively high log K value with the exception of C4. The log-transformed 2D-COS can be an analytical tool to understand the binding heterogeneity of DOM with HMs. The study can provide a guide for managing and controlling the effects of hydrophyte decomposition.

Metal- and metal/oxide-based engineered nanoparticles and nanostructures: a review on the applications, nanotoxicological effects, and risk control strategies

The production and demand of nanoparticles in the manufacturing sector and personal care products, release a large number of engineered nanoparticles (ENPs) into the atmosphere, aquatic ecosystems, and terrestrial environments. The intentional or involuntary incorporation of ENPs into the environment is carried out through different processes. The ENPs are combined with other compounds and release into the atmosphere, settling on the ground due to the water cycle or other atmospheric phenomena. In the case of aquatic ecosystems, the ENPs undergo hetero-aggregation and sedimentation, reaching different living organisms and flora, as well as groundwater. Accordingly, the high mobility of ENPs in diverse ecosystems is strongly related to physical, chemical, and biological processes. Recent studies have been focused on the toxicological effects of a wide variety of ENPs using different validated biological models. This literature review emphasizes the study of toxicological effects related to using the most common ENPs, specifically metal and metal/oxides-based nanoparticles, addressing different synthesis methodologies, applications, and toxicological evaluations. The results suggest negative impacts on biological models, such as oxidative stress, metabolic and locomotive toxicity, DNA replication dysfunction, and bioaccumulation. Finally, it was consulted the protocols for the control of risks, following the assessment and management process, as well as the classification system for technological alternatives and risk management measures of ENPs, which are useful for the transfer of technology and nanoparticles commercialization.

Accumulator plants and hormesis

Accumulation of metals by plants is an important area of investigation in plant ecology and evolution as well as in soil contamination/phytoremediation practices. This paper reports that hormetic-biphasic dose-response relationships were commonly observed for multiple agents (i.e. arsenic, cadmium, chromium, fluoride, lead, and zinc) and 20 species in plant (hyper)accumulator studies. The hormetic stimulation was related to metal accumulation in affected tissues, with the metal stimulation concentration zone unique for each metal, species, tissue, and endpoint studied. However, quantitative features of the hormetic dose response were similar across all (hyper)accumulation studies, with results independent of plant species, endpoints measured, and metal. The dose-dependent stimulatory and inhibitory/toxic plant responses were often associated with the up- and down-regulation of adaptive mechanisms, especially those involving anti-oxidative enzymatic processes. These findings provide a mechanistic framework to account for both the qualitative and quantitative features of the hormetic dose response in plant (hyper)accumulator studies.

Knowledge domain and emerging trends in nanoparticles and plants interaction research: A scientometric analysis

The potential releases of nanoparticles (NPs) into soil medium have drawn considerable attention due to the increasing production and application of NPs worldwide. Understanding the interactions between NPs and plants is particularly important to assess the risks of NPs in the soil ecosystem. Although important knowledge has been gained about the NPs-plants interactions, current results of numerous published articles are still scattered. Therefore, this paper reviews the scientific progress in the NPs-plants interactions via a scientometric analysis to identify the main gaps and to provide future perspectives. Scientific documents on the interaction of nanoparticles and plant research during the period January 2000-July 2020 have been collected from Web of Science core collection and analyzed using CiteSpace. Overall, 9 scientometric indicators, i.e. literature quantity and growth trend, contributing countries, authors, institutions, keywords, cited journals, cited authors, and cited articles, are employed to understand the results retrieved from the 961 documents collected. The number of studies on nano-plant interaction research has been growing at an average annual rate of 56%. 71 countries and around 3380 authors have contributed to this field. Among the cited journals, Environmental Science and Technology stands out as the most-cited journal followed by Science of the Total Environment and Environmental Pollution, respectively. Moreover, the keyword citation burst, an indicator of the most active area of research or emerging trend, indicates that the beneficial side of nanoparticles and the trophic transfer require further exploration. This paper will be beneficial for fully understanding the salient research themes and the research trends of nano-plant interaction in future.

Aquatic Macrophytes in Constructed Wetlands: A Fight against Water Pollution

There is growing concern among health institutions worldwide to supply clean water to their populations, especially to more vulnerable communities. Although sewage treatment systems can remove most contaminants, they are not efficient at removing certain substances that can be detected in significant quantities even after standard treatments. Considering the necessity of perfecting techniques that can remove waterborne contaminants, constructed wetland systems have emerged as an effective bioremediation solution for degrading and removing contaminants. In spite of their environmentally friendly appearance and efficiency in treating residual waters, one of the limiting factors to structure efficient artificial wetlands is the choice of plant species that can both tolerate and remove contaminants. For sometimes, the chosen plants composing a system were not shown to increase wetland performance and became a problem since the biomass produced must have appropriated destination. We provide here an overview of the use and role of aquatic macrophytes in constructed wetland systems. The ability of plants to remove metals, pharmaceutical products, pesticides, cyanotoxins and nanoparticles in constructed wetlands were compared with the removal efficiency of non-planted systems, aiming to evaluate the capacity of plants to increase the removal efficiency of the systems. Moreover, this review also focuses on the management and destination of the biomass produced through natural processes of water filtration. The use of macrophytes in constructed wetlands represents a promising technology, mainly due to their efficiency of removal and the cost advantages of their implantation. However, the choice of plant species composing constructed wetlands should not be only based on the plant removal capacity since the introduction of invasive species can become an ecological problem.

Native aquatic plants for phytoremediation of metals in outdoor experiments: implications of metal accumulation mechanisms, Soran City-Erbil, Iraq

An excessive amount of metals is toxic to plants, animals, and humans. The present study focuses on the efficacy of three local emergent aquatic plants; Veronica anagallis-aquatica L.; Mentha longifolia L. (Hudson) and Cyperus iria L. and one free-floating; Nasturtium officinale R. Br. for removal of metals (Fe, Pb, Zn, Cu, Mn, and Ni) from the wastewater, in outdoor sand pot experiments. The particular phytoremediation mechanisms were also investigated. The selected plants adapted and properly grew, as determined by their high biomass production and survival rate. Emergent plants (V. anagallis-aquatica and C. iria) accumulated high quantities of Fe, Cu, Ni, and Mn in roots (bioaccumulation factor for roots, BAF_root >1 and translocation factor, TF <1), therefore credited as strong excluders. The highest concentration of Fe was taken up by C. iria (>1000 mg/plant root), BAFs > 1, and TF < 1, and the revealed mechanism was phytostabilization. Mentha longifolia accumulated similar patterns of Zn in shoots and roots (BAFs >1 and TF >1), the involved mechanism was phytoextraction. Free-floating N. officinale showed the highest percentage of metal uptake and removal capacity for Pb (∼60% and ∼10 mg/d/g, respectively). Synergetic and plant genetic abilities need to be optimized to develop commercially useful practices.