Recent Developments in the Application of Nanomaterials in Agroecosystems

Nano hybrid fertilizers: A review on the state of the art in sustainable agriculture

The advent of Nanohybrid (NH) fertilizers represents a groundbreaking advancement in the pursuit of precision and sustainable agriculture. This review abstract encapsulates the transformative potential of these innovative formulations in addressing key challenges faced by modern farming practices. By incorporating nanotechnology into traditional fertilizer matrices, nanohybrid formulations enable precise control over nutrient release, facilitating optimal nutrient uptake by crops. This enhanced precision not only fosters improved crop yields but also mitigates issues of over-fertilization, aligning with the principles of sustainable agriculture. Furthermore, nanohybrid fertilizers exhibit the promise of minimizing environmental impact. Their controlled release mechanisms significantly reduce nutrient runoff, thereby curbing water pollution and safeguarding ecosystems. This dual benefit of precision nutrient delivery and environmental sustainability positions nanohybrid fertilizers as a crucial tool in the arsenal of precision agriculture practices. The intricate processes of uptake, translocation, and biodistribution of nutrients within plants are examined in the context of nanohybrid fertilizers. The nanoscale features of these formulations play a pivotal role in governing the efficiency of nutrient absorption, internal transport, and distribution within plant tissues. Factors affecting the performance of nanohybrid fertilizers are scrutinized, encompassing aspects such as soil type, crop variety, and environmental conditions. Understanding these variables is crucial for tailoring nanohybrid formulations to specific agricultural contexts, and optimizing their impact on crop productivity and resource efficiency. Environmental considerations are integral to the review, assessing the broader implications of nanohybrid fertilizer application. This review offers a holistic overview of nanohybrid fertilizers in precision and sustainable agriculture. Exploring delivery mechanisms, synthesis methods, uptake dynamics, biodistribution patterns, influencing factors, and environmental implications, it provides a comprehensive understanding of the multifaceted role and implications of nanohybrid fertilizers in advancing modern agricultural practices.

Emerging concern of nano-pollution in agro-ecosystem: Flip side of nanotechnology

Nanomaterials (NMs) have proven to be a game-changer in agriculture, showcasing their potential to boost plant growth and safeguarding crops. The agricultural sector has widely adopted NMs, benefiting from their small size, high surface area, and optical properties to augment crop productivity and provide protection against various stressors. This is attributed to their unique characteristics, contributing to their widespread use in agriculture. Human exposure from various components of agro-environmental sectors (soil, crops) NMs residues are likely to upsurge with exposure paths may stimulates bioaccumulation in food chain. With the aim to achieve sustainability, nanotechnology (NTs) do exhibit its potentials in various domains of agriculture also have its flip side too. In this review article we have opted a fusion approach using bibliometric based analysis of global research trend followed by a holistic assessment of pros and cons i.e. toxicological aspect too. Moreover, we have also tried to analyse the current scenario of policy associated with the application of NMs in agro-environment.

Pruning Boosts Growth, Yield, and Fruit Quality of Old Valencia Orange Trees: A Field Study

Pruning is an essential practice that helps control branch growth, optimize fruit size, and enhance fruit tree productivity. This study focused on ‘Valencia’ orange trees, which had experienced a decline in productivity after being cultivated on reclaimed lands for several years. The aim was to explore the impact of pruning intensity on vegetation growth, fruit yield, productivity, and fruit quality in these orange trees. The study involved 35-year-old ‘Valencia’ orange trees, which were subjected to four different levels of pruning. The pruning treatments included: T1—no pruning (control group), T2—light pruning (removal of 25% of main branches), T3—moderate pruning (removal of 50% of main branches), and T4—heavy pruning (removal of 75% of main branches). Each season, these pruning measures were consistently carried out on 15 February. The results indicated that the severity of pruning directly influenced vegetative growth parameters, such as shoot length and leaf area. As the pruning intensity increased, so did the growth of the vegetation. However, the overall volume of the tree’s canopy decreased compared to the control group. These findings provide insights into the relationship between pruning practices and the growth and productivity of ‘Valencia’ orange trees. The highest fruit yields were observed when pruning was carried out at a severity level of 75%, followed by 50 and 25%. These pruning treatments had a positive impact on various aspects of fruit quality, including weight, size, firmness, juice content, TSS (°Brix), TSS/acid ratio, and vitamin C content. Additionally, pruning contributed to a greater fruit yield per tree and an overall increase in the yield percentage. In essence, the findings suggest that pruning performed at different severity levels in February effectively promotes vegetation growth and enhances the physical and chemical properties of ‘Valencia’ orange trees. Notably, it resulted in a nearly 20% rise in fruit yield compared to the control group.

Production of copper nanoparticle-immobilized chitin nanofibers and their role in plant disease control

Chitin is used in agriculture to improve crop production; however, its use is limited due to difficulties in its handling. A chitin nanofiber (CNF) overcomes this issue and, due to its elicitor activity, has great potential for crop protection. To expand CNF utilization, a copper nanoparticles-based antimicrobic CNF (CuNPs/CNF) was prepared using a chemical reduction method. The formation of CuNPs was confirmed via scanning electron microscopy. Thermogravimetric analysis revealed that the amount of CuNPs on the CNF was dose-dependent on the precursor salt, copper acetate. CuNPs endowed the CNF with strong antimicrobial activity against Alternaria brassicicola and Pectobacterium carotovorum. Moreover, the CuNPs/CNF reduced pathogen infection in cabbage. The antimicrobial activity and disease prevention of the CuNPs/CNF was increased compared to the corresponding CNF or commercial agrochemical Bordeaux treatment. These results indicate that CuNPs conferred antimicrobial activity on the CNF and increased the efficacy of plant disease protection.

The Occurrence of Oxidative Stress Induced by Silver Nanoparticles in Chlorella vulgaris Depends on the Surface-Stabilizing Agent

Silver nanoparticles (AgNPs) are of great interest due to their antimicrobial properties, but their reactivity and toxicity pose a significant risk to aquatic ecosystems. In biological systems, AgNPs tend to aggregate and dissolve, so they are often stabilized by agents that affect their physicochemical properties. In this study, microalga Chlorella vulgaris was used as a model organism to evaluate the effects of AgNPs in aquatic habitats. Algae were exposed to AgNPs stabilized with citrate and cetyltrimethylammonium bromide (CTAB) agents and to AgNO₃ at concentrations that allowed 75% cell survival after 72 h. To investigate algal response, silver accumulation, ROS content, damage to biomolecules (lipids, proteins, and DNA), activity of antioxidant enzymes (APX, PPX, CAT, SOD), content of non-enzymatic antioxidants (proline and GSH), and changes in ultrastructure were analyzed. The results showed that all treatments induced oxidative stress and adversely affected algal cells. AgNO₃ resulted in the fastest death of algae compared to both AgNPs, but the extent of oxidative damage and antioxidant enzymatic defense was similar to AgNP-citrate. Furthermore, AgNP-CTAB showed the least toxic effect and caused the least oxidative damage. These results highlight the importance of surface-stabilizing agents in determining the phytotoxicity of AgNPs and the underlying mechanisms affecting aquatic organisms.

Multifunctional Nanoparticles and Nanopesticides in Agricultural Application

The unscientific application of pesticides can easily cause a series of ecological environmental safety issues, which seriously restrict the sustainable development of modern agriculture. The great progress in nanotechnology has allowed the continuous development of plant protection strategies. The nanonization and delivery of pesticides offer many advantages, including their greater absorption and conduction by plants, improved efficacy, reduced dosage, delayed resistance, reduced residues, and protection from natural enemies and beneficial insects. In this review, we focus on the recent advances in multifunctional nanoparticles and nanopesticides. The definition of nanopesticides, the types of nanoparticles used in agriculture and their specific synergistic mechanisms are introduced, their safety is evaluated, and their future application prospects, about which the public is concerned, are examined.

Sustainable Preparation of Graphene Quantum Dots for Metal Ion Sensing Application

Over the past several years, graphene quantum dots (GQDs) have been extensively studied in water treatment and sensing applications because of their exceptional structure-related properties, intrinsic inert carbon property, eco-friendly nature, etc. This work reported on the preparation of GQDs from the ethanolic extracts of eucalyptus tree leaves by a hydrothermal treatment technique. Different heat treatment times and temperatures were used during the hydrothermal treatment technique. The optical, morphological, and compositional analyses of the green-synthesized GQDs were carried out. It can be noted that the product yield of GQDs showed the maximum yield at a reaction temperature of 300 °C. Further, it was noted that at a treatment period of 480 min, the greatest product yield of about 44.34% was attained. The quantum yields of prepared GQDs obtained after 480 min of treatment at 300 °C (named as GQD/300) were noted to be 0.069. Moreover, the D/G ratio of GQD/300 was noted to be 0.532 and this suggested that the GQD/300 developed has a nano-crystalline graphite structure. The TEM images demonstrated the development of GQD/300 with sizes between 2.0 to 5.0 nm. Furthermore, it was noted that the GQD/300 can detect Fe³⁺ in a very selective manner, and hence the developed GQD/300 was successfully used for the metal ion sensing application.

Recent advances in nanotechnology for remediation of heavy metals

Heavy metal contamination of the environment has become an alarming environmental issue that has constituted serious threats to humans and the ecosystem. These metals have been identified as a priority class of pollutants due to their persistency in the environment and their potential to bioaccumulate in biological systems. Consequently, the remediation of heavy metals from various environmental matrices becomes a critical topic from the biological and environmental perspectives. To this end, various research interests have shifted to the need to put forward economically feasible and highly efficient approaches for mitigating these contaminants in the environment. Thus, numerous conventional approaches have reportedly been employed for the remediation of heavy metals, with each of the methods having its inherent limitations. More recently, studies have revealed that nanomaterials in their various forms show unique potential for the removal of various contaminants including heavy metals in comparison to their bulk counterparts making them a topic of importance to researchers in various fields. Also, various studies have documented specifically tailored nanomaterials that have been synthesized for the removal of heavy metals from various environmental matrices. This review provides up-to-date information on the application of nanotechnology for the remediation of heavy metals. It highlights various nanomaterials that have been employed for the remediation of heavy metals, current details on their methods of synthesis, factors affecting their adsorption processes, and the environmental and health impact of nanomaterials. Finally, it provides the challenges and future trends of nanomaterials for heavy metal removal.

Biosynthesized metal oxide nanoparticles for sustainable agriculture: next-generation nanotechnology for crop production, protection and management

The current agricultural sector is not only in its most vulnerable state but is also becoming a threat to our environment due to expanding population and growing food demands along with worsening climatic conditions. In addition, numerous agrochemicals presently being used as fertilizers and pesticides have low efficiency and high toxicity. However, the rapid growth of nanotechnology has shown great promise to tackle these issues replacing conventional agriculture industries. Since the last decade, nanomaterials especially metal oxide nanoparticles (MONPs) have been attractive for improving agricultural outcomes due to their large surface area, higher chemical/thermal stability and tunable unique physicochemical characteristics. Further, to achieve sustainability, researchers have been extensively working on ecological and cost-effective biological approaches to synthesize MONPs. Hereby, we have elaborated on recent successful biosynthesis methods using various plants/microbes. Furthermore, we have elucidated different mechanisms for the interaction of MONPs with plants, including their uptake/translocation/internalization, photosynthesis, antioxidant activity, and gene alteration, which could revolutionize crop productivity/yield through increased nutrient amount, photosynthesis rate, antioxidative enzyme level, and gene upregulations. Besides, we have briefly discussed about functionalization of MONPs and their application in agricultural-waste-management. We have further illuminated recent developments of various MONPs (Fe₂O₃/ZnO/CuO/Al₂O₃/TiO₂/MnO₂) as nanofertilizers, nanopesticides and antimicrobial agents and their implications for enhanced plant growth and pest/disease management. Moreover, the potential use of MONPs as nanobiosensors for detecting nutrients/pathogens/toxins and safeguarding plant/soil health is also illuminated. Overall, this review attempts to provide a clear insight into the latest advances in biosynthesized MONPs for sustainable crop production, protection and management and their scope in the upcoming future of eco-friendly agricultural nanotechnology.

Effects of Phytogenically Synthesized Bimetallic Ag/ZnO Nanomaterials and Nitrogen-Based Fertilizers on Biochemical and Yield Attributes of Two Wheat Varieties

Wheat is the most important staple food worldwide, but wheat cultivation faces challenges from high food demand. Fertilizers are already in use to cope with the demand; however, more unconventional techniques may be required to enhance the efficiency of wheat cultivation. Nanotechnology offers one potential technique for improving plant growth and production by providing stimulating agents to the crop. In this study, plant-derived Ag/ZnO nanomaterials were characterized using UV-Vis spectroscopy, SEM, EDX, FTIR, and XRD methods. Various concentrations of phytogenically synthesized Ag/ZnO nanomaterials (20, 40, 60, and 80 ppm) and nitrogen-based fertilizers (urea and ammonium sulphate 50 and 100 mg/L) were applied to wheat varieties (Galaxy-13 and Pak-13). The results obtained from this research showed that application of 60 ppm Ag/ZnO nanomaterials with nitrogenous fertilizers (50 and 100 mg/L) were more effective in improving biochemistry and increasing yield of wheat plants by reducing enzymatic and non-enzymatic antioxidants (proline content, soluble sugar content, malondialdehyde, total phenolic content, total flavonoid content, superoxide dismutase, peroxidase, and catalase); and significantly increasing the protein content, number of grains per pot, spike length, 100-grain weight, grain yield per pot, and harvest index of both wheat varieties, compared to untreated plants. These findings allow us to propose Ag/ZnO nanomaterial formulation as a promising growth- and productivity-improvement strategy for wheat cultivation.

Plant development and crop protection using phytonanotechnology: A new window for sustainable agriculture

Most developing nations' economies are built on agriculture and most of their citizens rely on it for survival. Global agricultural systems are experiencing tough and unprecedented challenges in the age of changing climate. Every year, the world's population grows, necessitating increased agrarian productivity. As a result, there has been a movement toward utilizing emerging technologies, such as nanotechnology. Nanotechnology with plant systems has inspired great interest in the current scenario in developing areas that come under the umbrella of agriculture and develop environmental remediation strategies. Plant-mediated synthesized nanoparticle (NPs) are eco-friendly, less time consuming, less expensive, and provide long-term product safety. Simultaneously, it provides tools that have the potentiality as "magic bullets" containing nutrients, fungicides, fertilizers, herbicides, or nucleic acids that target specific plant tissues and deliver their payload to the targeting location of the plant to achieve the intended results for environmental monitoring and pollution resistance. In this perspective, the classification and biological activities of different NPs on agroecosystem are focused. Furthermore, absorption, transport, and modification of NPs in plants were thoroughly examined. Some of the most promising new technologies e.g., nanotechnology to increase crop agricultural input efficiency and reduce biotic and abiotic stresses are also discussed. Potential development and implementation challenges were explored, highlighting the importance of using a systems approach when creating suggested nanotechnologies.

Progress and Prospects of Nanocellulose-Based Membranes for Desalination and Water Treatment

Membrane-based desalination has proved to be the best solution for solving the water shortage issues globally. Membranes are extremely beneficial in the effective recovery of clean water from contaminated water sources, however, the durability as well as the separation efficiency of the membranes are restricted by the type of membrane materials/additives used in the preparation processes. Nanocellulose is one of the most promising green materials for nanocomposite preparation due to its biodegradability, renewability, abundance, easy modification, and exceptional mechanical properties. This nanocellulose has been used in membrane development for desalination application in the recent past. The study discusses the application of membranes based on different nanocellulose forms such as cellulose nanocrystals, cellulose nanofibrils, and bacterial nanocellulose for water desalination applications such as nanofiltration, reverse osmosis, pervaporation, forward osmosis, and membrane distillation. From the analysis of studies, it was confirmed that the nanocellulose-based membranes are effective in the desalination application. The chemical modification of nanocellulose can definitely improve the surface affinity as well as the reactivity of membranes for the efficient separation of specific contaminants/ions.

A Star Polyamine-Based Nanocarrier Delivery System for Enhanced Avermectin Contact and Stomach Toxicity against Green Peach Aphids

The unscientific application of synthesized/botanical pesticides has not only brought the resistance of plant pathogens and pests, but also led to serious environmental pollution. In recent years, various nano-delivery systems have been used for the development of environmental-friendly pesticides with improved efficacy. Herein, the current study constructed an efficient avermectin B1a (AVM) nano-delivery system based on a star polyamine (SPc) and focused on the characterization and bioactivity of SPc-loaded AVM at various mass ratios. The hydroxyl groups of AVM could assemble with carbonyl groups of SPc through hydrogen bond and van der Waals forces, and the self-assembly of AVM and SPc formed nearly spherical particles of AVM/SPc complex with nanoscale size. The contact angle of SPc-loaded AVM decreased with the increasing mass ratio of SPc, revealing the easier distribution and spreading of the AVM/SPc complex. Furthermore, the stomach and contact toxicity of AVM/SPc complex also increased along with the increasing SPc mass ratio, which could be attributed to the enhanced systemic transportation in plants, enlarged contact area to insect pests and stronger permeability across the insect cuticle. The current study provides an efficient nano-delivery system for increasing stomach and contact toxicity of pesticides with wide applications in the agricultural field.

Engineered Cu-PEN Composites at the Nanoscale: Preparation and Characterisation

As polymeric materials are already used in many industries, the range of their applications is constantly expanding. Therefore, their preparation procedures and the resulting properties require considerable attention. In this work, we designed the surface of polyethylene naphthalate (PEN) introducing copper nanowires. The surface of PEN was transformed into coherent ripple patterns by treatment with a KrF excimer laser. Then, Cu deposition onto nanostructured surfaces by a vacuum evaporation technique was accomplished, giving rise to nanowires. The morphology of the prepared structures was investigated by atomic force microscopy and scanning electron microscopy. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy revealed the distribution of Cu in the nanowires and their gradual oxidation. The optical properties of the Cu nanowires were measured by UV-Vis spectroscopy. The sessile drop method revealed the hydrophobic character of the Cu/PEN surface, which is important for further studies of biological responses. Our study suggests that a combination of laser surface texturing and vacuum evaporation can be an effective and simple method for the preparation of a Cu/polymer nanocomposite with potential exploitation in bioapplications; however, it should be borne in mind that significant post-deposition oxidation of the Cu nanowire occurs, which may open up new strategies for further biological applications.

Effects of Liquid Phase Nano Titanium Dioxide (TiO2) on Seed Germination and Seedling Growth of Camphor Tree

It is of great significance to popularize and apply nanotechnology in forest plantations for the high-quality development of such areas. Camphor trees have good ecological and environmental benefits and are economic, which makes them worthy of widespread popularization and promotion. In this paper, we successfully synthesized bulk and rod-like TiO₂ powder and used it to study the influence of camphor seed germination and seedling growth. The germination rate, germination potential, germination index activity index of camphorwood seed during germination were measured by TiO₂ solution with different morphology. Meanwhile, the fresh weight, root length and seedling height of seedlings, as well as the activities of CAT, SOD and POD and MDA content in the seedlings were measured in detail. The difference in the promoting effect between bulk and rod TiO₂ powder was compared. The possible reasons are also explained. The results showed that bulk and rod-like TiO₂ solution improved the activities of SOD, POD and CAT, and increased the resilience of camphor seedlings. Moreover, the rod-like TiO₂ solution has a stronger osmotic effect on seed, and has a better effect on promoting seed germination and seedling growth. The study on the influence of nano-TiO₂ concentration also further showed that the treatment of nano-TiO₂ solution with appropriate concentration could effectively promote seed germination and seedling growth, and enhance its adoptability to adversity; but excessive concentration will bring some side effects, which was not conducive to seed germination and seedling growth. In general, the results of this study provide a theoretical basis and technical guidance for the practical application of nanotechnology in camphor seedling and afforestation production.

An Effective Label-Free Electrochemical Aptasensor Based on Gold Nanoparticles for Gluten Detection

Nanomaterials can be used to modify electrodes and improve the conductivity and the performance of electrochemical sensors. Among various nanomaterials, gold-based nanostructures have been used as an anchoring platform for the functionalization of biosensor surfaces. One of the main advantages of using gold for the modification of electrodes is its great affinity for thiol-containing molecules, such as proteins, forming a strong Au-S bond. In this work, we present an impedimetric biosensor based on gold nanoparticles and a truncated aptamer for the quantification of gluten in hydrolyzed matrices such as beer and soy sauce. A good relationship between the R_ct values and PWG-Gliadin concentration was found in the range between 0.1–1 mg L⁻¹ of gliadin (corresponding to 0.2–2 mg L⁻¹ of gluten) with a limit of detection of 0.05 mg L⁻¹ of gliadin (corresponding to 0.1 mg L⁻¹ of gluten). The label-free assay was also successfully applied for the determination of real food samples.

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

Controlled release systems of agrochemicals have been developed in recent years. However, the design of intelligent nanocarriers that can be manufactured with renewable and low-cost materials is still a challenge for agricultural applications. Lignocellulosic building blocks (cellulose, lignin, and hemicellulose) are ideal candidates to manufacture ecofriendly nanocarriers given their low-cost, abundancy and sustainability. Complexity and heterogeneity of biopolymers have posed challenges in the development of nanocarriers; however, the current engineering toolbox for biopolymer modification has increased remarkably, which enables better control over their properties and tuned interactions with cargoes and plant tissues. In this mini-review, we explore recent advances on lignocellulosic-based nanocarriers for the controlled release of agrochemicals. We also offer a critical discussion regarding the future challenges of potential bio-based nanocarrier for sustainable agricultural development.

Recent Advancements in the Nanomaterial Application in Concrete and Its Ecological Impact

At present, nanotechnology is a significant research area in different countries, owing to its immense ability along with its economic impact. Nanotechnology is the scientific study, development, manufacturing, and processing of structures and materials on a nanoscale level. It has tremendous application in different industries such as construction. This study discusses the various progressive uses of nanomaterials in concrete, as well as their related health risks and environmental impacts. Nanomaterials such as nanosilica, nano-TiO₂, carbon nanotubes (CNTs), ferric oxides, polycarboxylates, and nanocellulose have the capability to increase the durability of buildings by improving their mechanical and thermal properties. This could cause an indirect reduction in energy usage and total expenses in the concrete industry. However, due to the uncertainties and irregularities in size, shape, and chemical compositions, some nanosized materials might have harmful effects on the environment and human health. Acknowledgement of the possible beneficial impacts and inadvertent dangers of these nanosized materials to the environment will be extremely important when pursuing progress in the upcoming years. This research paper is expected to bring proper attention to the probable effects of construction waste, together with the importance of proper regulations, on the final disposal of the construction waste.

Multi-Walled Carbon Nanotubes Improved Development during In Vitro Multiplication of Sugarcane (Saccharum spp.) in a Semi-Automated Bioreactor

Carbon nanotubes play an important role in plant biotechnology due to their effects on the growth and differentiation of cells, tissues, organs, and whole plants. This study aimed to evaluate the effect of multi-walled carbon nanotubes (MWCNTs) during in vitro multiplication of sugarcane (Saccharum spp.) using a temporary immersion system. Morphological characterization of MWCNTs was carried out under a transmission electron microscope. Different concentrations (0, 50, 100, 200 mg L⁻¹) of MWCNTs were added to Murashige and Skoog liquid culture medium in the multiplication stage. At 30 d of culture, number of shoots per explant, shoot length, number of leaves per shoot, total chlorophyll, dry matter percentage, carbon percentage, and macro- and micronutrient content were evaluated. Results showed an increase in the development of sugarcane shoots at concentrations of 100 and 200 mg L⁻¹ MWCNT. Total chlorophyll content increased at concentrations of 50 and 100 mg L⁻¹ MWCNT, whereas macro- and micronutrient content was variable at the different MWCNT concentrations. Results suggest a hormetic effect, characterized by stimulation at low concentrations. In conclusion, the use of low concentrations of MWCNTs had positive effects on development, total chlorophyll, carbon percentage, and macro- and micronutrient (N, Ca, S, Fe, Cu, Zn and Na) contents during in vitro multiplication of sugarcane and may have a potential use in other species of agricultural interest.

Insights into the mechanism of multi-walled carbon nanotubes phytotoxicity in Arabidopsis through transcriptome and m6A methylome analysis

With the increasing production and wide application of carbon nanotubes (CNTs), they are inevitably released into the natural environment and ecosystems, where plants are the main primary producers. Hence, it is imperative to understand the toxic effects of CNTs on plants. The molecular mechanisms underlying the toxic effects of CNTs on plants are still unclear. Therefore, in the present study, we investigated the effects of high concentrations of multi-walled CNTs (MWCNTs) on Arabidopsis. Root elongation and leaf development were severely inhibited after MWCNT exposure. Excess production of H₂O₂, O₂^-, and malondialdehyde was observed, indicating that MWCNTs induced oxidative stress. The antioxidant system was activated to counter MWCNTs-induced oxidative stress. Combinatorial transcriptome and m6A methylome analysis revealed that MWCNTs suppressed auxin signaling and photosynthesis. Reactive oxygen species metabolism, toxin metabolism, and plant responses to pathogens were enhanced to cope with the phytotoxicity of MWCNTs. Our results provide new insights into the molecular mechanisms of CNT phytotoxicity and plant defense responses to CNTs.

AC Susceptibility Studies under DC Fields in Superspinglass Nanomaghemite-Multiwall Carbon Nanotube Hybrid

Magnetic properties of maghemite (γ-Fe2O3) nanoparticles grown on activated multiwall carbon nanotubes have been studied by alternating current (AC) magnetic susceptibility experiments performed under different temperatures, frequencies, and applied magnetic fields. Transmission electron images have suggested that the γ-Fe2O3 nanoparticles are not isolated and have an average size of 9 nm, but with a relatively broad size distribution. The activation energies of these 9 nm γ-Fe2O3 nanoparticles, determined from the generalized Vogel–Fulcher relation, are reduced upon increasing the direct current (DC) field magnitude. The large activation energy values have indicated the formation of a superspinglass state in the γ-Fe2O3 nanoparticle ensemble, which were not observed for pure γ-Fe2O3 nanoparticles, concluding that the multiwall carbon nanotubes favored the appearance of highly concentrated magnetic regions and hence the formation of superspinglass state. Magnetic relaxation studies, using Argand diagrams recorded for DC probe fields (<20 kOe) below the magnetic blocking temperature at 100 and 10 K, have revealed the presence of more than one relaxation process. The behavior of the ensemble of γ-Fe2O3 nanoparticles can be related to the superspinglass state and is also supported by Almeida–Thouless plots.

Nanoimpact in Plants: Lessons from the Transcriptome

Transcriptomics studies are available to evaluate the potential toxicity of nanomaterials in plants, and many highlight their effect on stress-responsive genes. However, a comparative analysis of overall expression changes suggests a low impact on the transcriptome. Environmental challenges like pathogens, saline, or drought stress induce stronger transcriptional responses than nanoparticles. Clearly, plants did not have the chance to evolve specific gene regulation in response to novel nanomaterials; but they use common regulatory circuits with other stress responses. A shared effect with abiotic stress is the inhibition of genes for root development and pathogen response. Other works are reviewed here, which also converge on these results.