Carbonaceous Nanomaterials Research Articles

Influence of tool rotation speeds on mechanical and morphological properties of friction stir processed nano hybrid composite of MWCNT-Graphene-AZ31 magnesium

Abstract The ever-increasing demand for light weighted hard materials for transportation industries encouraged researchers to develop composites with excellent mechanical properties which can transform it into more economical and eco-friendly. Reinforcing the metals with carbonaceous nanomaterials are progressively in focus due to their excellent capability to inculcate and tailor the properties of MMCs. In the present research, a hybrid nanocomposite of MWCNT-Graphene-AZ31 Mg alloy has been developed by using variable tool rotation speeds with friction stir processing (FSP). Optimized reinforcement ratio of 1.6% vol. MWCNT and 0.3% vol. of graphene have been used with variable tool rotation speeds, whereas other processing parameters are kept constant. The developed specimens were investigated using standard testing equipment for evaluating and comparing the mechanical properties on the basis of the microstructure of the processing regions and their morphological analysis, according to the ASTM standards. The obtained results revealed an improvement of 19.72% in microhardness and 77.5% of compressive strength in comparison with the base metal AZ 31 Magnesium alloy, with a tool rotational speed of 1400 rpm. The values of tensile stress and percentage area reduction were recorded as less than that of the base metal matrix, but an increasing trend has been observed in the values of both with the improvement on rotational speeds of the tool. The effectual strengthening mechanisms are analyzed on the bases of SEM images and observed that discussed and found that grain refinement strengthening is the major contributor to the strength of the nanocomposite.

Onion-like carbon-modified TiO2 coating by suspension plasma spray with enhanced photocatalytic performances

Onion-like carbon (OLC), a novel carbonaceous nanomaterial, has already attracted widespread concern due to its exceptional physicochemical properties. In this work, OLC nanoparticles (5–10 nm in diameter) were used as additives to fabricate nanotitania (TiO2) coatings by suspension plasma spray (SPS) for photocatalytic degrading methylene blue. The starting microstructure and chemistry of both OLC and TiO2 nanoparticles were retained after deposition process, and homogeneous dispersion of OLC in the coating was detected, which indicates SPS is an alternative and efficient technique to fabricate semiconductor-carbonaceous nanomaterials coatings. The new TiO2-OLC composite shows typical mesoporous structure. And aligned interfacial bond of OLC spheres with the (101) plane of anatase crystals was revealed. TiO2-OLC shows enhanced activity of degrading methylene blue under both UV and visible light irradiation than pure TiO2 coating. We have elucidated the enhancement mechanism from three aspects, namely, reduction of the bandgap, minimization of photo-induced-carriers recombination, and promotion of adsorption capacity for methylene blue.

Grouping of carbonaceous nanomaterials based on association of patterns of inflammatory markers in BAL fluid with adverse outcomes in lungs

Carbonaceous nanomaterials (CNMs) are universally being used to make commodities, as they present unique opportunities for development and innovation in the fields of engineering, biotechnology, etc. As technology advances to incorporate CNMs in industry, the potential exposures associated with these particles also increase. CNMs have been found to be associated with substantial pulmonary toxicity, including inflammation, fibrosis, and/or granuloma formation in animal models. This study attempts to categorize the toxicity profiles of various carbon allotropes, in particular, carbon black, different multi-walled carbon nanotubes, graphene-based materials, and their derivatives. Statistical and machine learning-based approaches were used to identify groups of CNMs with similar pulmonary toxicity responses from a panel of proteins measured in bronchoalveolar lavage (BAL) fluid samples and with similar pathological outcomes in the lungs. Thus, grouped particles, based on their pulmonary toxicity profiles, were used to select a small set of proteins that could potentially identify and discriminate between the toxicity profiles associated within each group. Specifically, MDC/CCL22 and MIP-3β/CCL19 were identified as common protein markers associated with both toxicologically distinct groups of CNMs. In addition, the persistent expression of other selected protein markers in BAL fluid from each group suggested their ability to predict toxicity in the lungs, i.e. fibrosis and microgranuloma formation. The advantages of such approaches can have positive implications for further research in toxicity profiling.

Cascading Ecological Impacts of Fullerenes in Freshwater Ecosystems.

Carbonaceous nanomaterials, such as fullerenes (C60, C70) and the derivative phenyl-C61-butyric acid methyl ester (PCBM), have promising application in solar energy technologies. Although the acute ecotoxicity of C60 has been reported widely in the literature, ecotoxicity assays for different fullerene forms and broader ecosystem impact studies remain scarce. To address these knowledge gaps, acute, chronic, and life stage exposure studies with freshwater zooplankton, Daphnia magna and Daphnia pulex, were performed for each material. Experimental results indicated that C60 and PCBM are not acutely toxic at estimated environmentally relevant concentrations; however, C70 had significant acute effects. All forms of fullerene caused a gradual elevation in heart rate over time and visual darkening of the Daphnia spp. carapace. The impact of fullerenes on susceptibility to predation was then assessed experimentally by presenting D. pulex to the visual predator Lepomis macrochirus (bluegill). Predation risk was significantly increased in fullerene-exposed D. pulex. The present study underscores the need to broaden the scope of traditional ecotoxicity for emerging materials: studies are required that evaluate portfolios of related nanomaterials and that capture chronic and cascading ecosystem-level effects. Environ Toxicol Chem 2019;38:1714-1723. © 2019 SETAC.

Comparative study of the characteristics and fluorescent properties of three different biochar derived‑carbonaceous nanomaterials for bioimaging and heavy metal ions sensing

Three types of biochar (microalgae, rice straw and sorghum straw) from biomass thermal conversion production were tested for producing biochar-derived carbonaceous nanomaterials (BCN). BCN were obtained after using chemical depolymerisation and solvent extraction, NanoRefinery process. Microalgae biochar-derived carbonaceous nanomaterials (MAB-CN), rice straw biochar-derived carbonaceous nanomaterials (RSB-CN) and sorghum straw biochar-derived carbonaceous nanomaterials (SSB-CN) were characterised using spectroscopic and microscopic techniques. This characterisation evidenced significant differences among the three BCN with MAB-CN exhibiting greater structural differences compared to RSB-CN and SSB-CN. Biocompatibility, cellular uptake, and cellular localisation were evaluated using three yeast species, Saccharomyces cerevisiae, Candida albicans, and Yarrowia lipolytica. While all BCN were biocompatible, the degree of biocompatibility for each species was dependent on pH, BCN concentration and BCN type. Additionally, BCN were evaluated as transducers for the detection of 12 heavy metal ions. MAB-CN, RSB-CN, and SSB-CN had different responses to the 12 heavy metal ions. The SSB-CN/Cu (II) and the MAB-CN/Zn (II) combinations evidenced selectivity over the other metal ions with these combinations having limits of detection of 0.0125 μM and 9 μM, respectively. The results from this research pave the way for BCN novel applications for bioimaging and heavy metal ions sensing probes.

Review Article: Layer-structured carbonaceous materials for advanced Li-ion and Na-ion batteries: Beyond graphene

Two-dimensional (2D) materials, including transition-metal chalcogenides, MXenes, and carbonaceous materials, have been regarded as promising alternatives to commercial graphite for use as advanced lithium/sodium-ion battery (LIB/SIB) anodes owing to the enriched active sites and expanded interlayer spacing for higher energy/power densities. The carbonaceous 2D materials, either graphitic or nongraphitic structures, arise from varieties of natural or artificial sources with potential scalable synthesis, high conductivity, and low cost and have shown great advantages for sustainable energy conversion and storage applications. Considering the importance of 2D carbonaceous materials beyond graphene, a timely and systematic overview of the very recent progress of layer-structured carbonaceous materials is vital for exploring high-performance anode materials for advanced LIB/SIBs. The recent advances in Li+/Na+ ion storage in various novel morphological variants of 2D carbonaceous materials prepared by a variety of techniques are discussed along with important models presented in the literature to explain the excess lithium/sodium storage. This review will also discuss the opportunities, challenges, and perspectives of the 2D carbonaceous nanomaterials beyond graphene in the field of energy storage.

Size distribution of Carbonaceous Nanomaterials:

カーボンナノチューブ(CNT)は，日本において，安定した性質の製品が大量かつ安価に供給できる製造法が開発された．CNTは少量でも樹脂の特性を向上させることが可能なため，産業への応用が期待される材料であり，使用量が増加している．CNTはナノマテリアルであるため曝露対策が必要であるが，曝露測定を行う際には，CNTの飛散の特性を考えてサンプラーを選定する必要がある．本研究では，模擬的に発生したCNTエアロゾルを衝突型の多段インパクターで捕集して，炭素分析により炭素成分の情報と粒径の質量分布，走査型電子顕微鏡観察による形態の情報を得た．CNTは凝集粒子として飛散することが多いが，CNTの種類によっては単独の短い繊維が繊維状粒子として飛散するものがあることを観測した．凝集粒子を多段インパクターで捕集する際の留意点を明らかにし，以前提案したCNTの定量法の妥当性を確認した．

NanoRefinery of carbonaceous nanomaterials: Complementing dairy manure gasification and their applications in cellular imaging and heavy metal sensing

This article describes an efficient method, combining chemical oxidation and acetone extraction, to produce carbonaceous nanomaterials from dairy manure biochar. The optical and mechanical properties are similar to methods previously reported carbonaceous nanomaterials from biomass. Our novel process cuts the processing time in half and drastically reduces the energy input required. The acetone extraction produced 10 fractions with dairy manure biochar-derived carbonaceous nanomaterials (DMB–CNs). The fraction with the carbonaceous nanomaterials, DMB–CN-E1, with highest fluorescence was selected for in-depth characterisation and for initial testing across a range of applications. DMB–CN-E1 was characterised using atomic force microscope, electrophoresis, and spectrophotometric methods. DMB–CN-E1 exhibited a lateral dimension between 11 and 28 nm, a negative charge, and excitation/emission maxima at 337/410 nm, respectively. The bioimaging potential of DMB–CN-E1 evidenced different locations and different interactions with the cellular models evaluated. DMB–CN-E1 was quenched by several heavy metal ions showing a future application of these materials in heavy metal ion detection and/or removal. The demonstrated capabilities in bioimaging and environmental sensing create the opportunity for generating added-value nanomaterials (NanoRefinery) from dairy manure biochar gasification and, thus, increasing the economic viability of gasification plants.

Multivariate analysis of biochar-derived carbonaceous nanomaterials for detection of heavy metal ions in aqueous systems

This article focuses on implementing multivariate analysis to evaluate biochar-derived carbonaceous nanomaterials (BCN) from three different feedstocks for the detection and differentiation of heavy metal ions in aqueous systems. The BCN were produced from dairy manure, rice straw and sorghum straw biochar using our NanoRefinery process. The NanoRefinery process transforms biochar into advanced nanomaterials using depolymerisation/chemical oxidation and purification of nanomaterials using solvent extraction. Dairy manure biochar-derived carbonaceous nanomaterials (DMB-CN), rice straw biochar-derived carbonaceous nanomaterials (RSB-CN) and sorghum straw biochar-derived carbonaceous nanomaterials (SSB-CN) were utilised as probes for the evaluation of their fluorescent properties and the detection of heavy metal ions. The BCN fluorescence quenching and fluorescence recovery was tested with lead (Pb2+), nickel (Ni2+), copper (Cu2+) and mercury (Hg2+). Principal component analysis (PCA) and discriminant analysis were used to differentiate among heavy metal ions in water samples. The BCN from different feedstocks had different characteristics and produced different interactions with heavy metal ions. DMB-CN had the highest quenching for Hg2+ and Ni2+ while SSB-CN and RSB-CN responded best to Cu2+ and Pb2+, respectively. The fluorescence quenching was modelled using linear and empirical functions. PCA and discriminant analysis used the quenching measurements to differentiate heavy metal ions in aqueous system. A key result was that the discriminant analysis had a 100% accuracy to detect Pb2+, 66% for Ni2+ and Cu2+, and 33% for Hg2+. This study has shown that biochar-derived carbonaceous nanomaterials could be used in heavy metal ions sensing applications. This is the first step in the development of a fast and accurate method for the detection of heavy metal ions in waters using environmentally friendly BCN.

A label-free quantification method for measuring graphene oxide in biological samples

Characterization of carbonaceous nanomaterials (CNMs) exposure is a key step and of great importance towards a better understanding of their toxicity and underlying mechanisms. However, it has been bottlenecked for lack of valid methods capable of quantifying cell-associated CNMs. Here, we developed a new economical and convenient method based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) that could accumulate graphene oxide (GO) at the interface between the loading well and the gel. The sharp black band formed there can be digitalized and the intensity quantified, which was proportional to the amount of GO loaded onto the gel. The method has a detection limit of 84.1 ng. We showed that the amount of GO in three different cell models, mouse macrophage cells (Raw264.7), human epithelial cells (A549) and mouse mesenchymal stem cells (MSC), could be accurately quantified by this assay, with the uptake rates decreasing in the order of MSC > Raw264.7 > A549. The results were consistent with the fluorescent imaging on cells exposed to fluorescence-labeled GO and TEM examination on ultrathin cell sections. The surprisingly highest uptake rate of MSC might be due to their abundant intracellular vesicles, which deserves further investigation. The novel method provides a complementary quantitative tool to the use of radioactive markers and fluorescent labeling of carbon nanomaterials and may facilitate the toxicological studies on carbon nanomaterials.

Use of Ni Catalysts Supported on Biomorphic Carbon Derived From Lignocellulosic Biomass Residues in the Decomposition of Methane

In this work, we present the results of production of carbonaceous nanomaterials by decomposition of methane on a catalyst of Ni supported on a Biomorphic Carbon. The catalyst was prepared by thermal decomposition in a reductive atmosphere of vine shoots previously impregnated with the Ni precursor. In order to optimize the reaction productivity and selectivity, the effect of the main operational conditions (reaction temperature and feed composition) has been studied in a thermobalance. The main textural properties, BET area of 63 m2/g and 56% of microporosity, of the catalyst synthesized indicates that these materials are suitable for gas-phase reactions even in harsh conditions. Thus, the catalyst has proved to be active in the synthesis of carbon nanofibres and graphene related materials at elevated temperatures. The productivity, type and quality of the carbonaceous nanomaterials obtained are deeply dependent on the operating conditions during the reaction. As an important fact, is has been obtained that the reaction temperature strongly affects the type of the nanomaterial produced. Thus, it is produced CNFs of bamboo type at temperatures until 850 oC. Above this critical temperature, it is mainly obtained nanolayers of graphitic nature. The characterization results indicate that the highest quality graphenic materials were obtained operating at 950 °C with 14.3 % of CH4 and 14.3 % of H2. The kinetic model used to analyze the experimental data is based on the more relevant stages of the mechanism of reaction.

Interaction between functionalized multiwalled carbon nanotubes and MS2 bacteriophages in water

Fate and transport of carbon nanomaterials can be strongly dependent on the interaction with secondary particulates in the aquatic systems. Bio-particulates in water, e.g., viruses with charged and hydrophobic surface moieties, may profoundly influence the interfacial behavior and hence the environmental fate of nanomaterials (and vice versa). This study systematically evaluates the interfacial interaction of acid-functionalized multiwalled carbon nanotubes (MWNTs) with MS2 bacteriophages, or heteroaggregation behavior of these particulates, under mono- and di-valent cations and with Suwannee River humic acid (SRHA). Results indicate that the highest concentration of MS2 (i.e., MWNT:MS2 of 100:1) renders exceptional stability of MWNTs, even in high salinity conditions. However, at lower MS2 concentrations (i.e., MWNT:MS2 of 1000:1 and 10,000:1), the suppression of MWNT heteroaggregation rate is not as significant. The observed enhanced stability is likely caused by the preferential attachment of the MS2 capsids onto MWNT surfaces, which is mediated by electrostatic attraction (between negatively charged oxygen-containing moieties on MWNTs and positively charged amino acid residues on MS2 surfaces) and/or by MS2 capsids with positive hydropathy index (indicating strong hydrophobicity). Presence of SRHA also shows stability enhancement; however, at lower MS2 concentrations, SRHA dominated the heteroaggregation behavior. These results implicate that preferential interaction between virus capsids (i.e., MS2 and may be other waterborne viruses) and carbonaceous nanomaterials may influence environmental transport of both in aquatic environments.

Recent applications of carbonaceous nanosorbents for the analysis of mycotoxins in food by liquid chromatography: a short review

Carbonaceous nanomaterials (multi-walled carbon nanotubes (MWCNTs), graphene, and graphene oxide (GO)) have attracted attention over the last decade as adsorbents suitable for the analysis of organic and inorganic pollutants. In the present paper we review methods of mycotoxin analysis that involve sample extraction with carbonaceous nanosorbents, reported from 2011 onwards. Recent studies have highlighted the advantages of magnetically modified MWCNTs and GO in mycotoxin analysis, which may enable sample isolation through magnetic separation, reduce the interaction of nanoparticles, and enhance the recovery of analytes. The papers covered in this review point to promising applications of functionalised carbonaceous nanosorbents in mycotoxin analysis. While GO based sorbents can be effective for the adsorption of relatively polar aflatoxins, MWCNTs with high specific surface area and reduced agglomeration achieved through modification with silica and magnetic particles are preferred for the extraction of less polar mycotoxins.

Voltammetric Sensors Based on Various Nanomaterials for the Determination of Sulfonamides

Background: The widespread applications of sulphonamides, as antibacterial or antimicrobial agents, and their mechanism of actions in the body, have changed their determination to an important issue in the area of human health. Objective: Here, history of developing voltammetric sensors based on nanomaterials for the detection of sulfonamides including sulfadiazine, sulfamethoxazole, sulfacetamide, sulfadimethoxine, sulfathiazole, sulfamethiazole and sulfamerazine is reviewed. Modified electrodes based on various nanomaterials (carbonaceous nanomaterials, Metallic Nanoparticles (MNPs), conducting nanopolymers) have been reported, and studies showed that nanomaterials have been mostly used to overcome problems like the poor sensitivity and selectivity of bare electrodes. The study covers the properties of each sensor in detail, and reports and compares the linear ranges, Limits of Detection (LODs), reproducibility, and reusability of the electrodes reported so far.

Layering of a film of carboxymethyl-botryosphaeran onto carbon black as a novel sensitive electrochemical platform on glassy carbon electrodes for the improvement in the simultaneous determination of phenolic compounds

In this work, a modification of a glassy carbon electrode (GCE) is presented for the first time using the polysaccharide carboxymethyl-botryosphaeran (CMB) and nanostructured carbon black (CB). The combination of the carbohydrate biopolymer and the carbonaceous nanomaterial (CMB-CB/GCE) showed improvements in the voltammetric responses of dopamine (DOP) and paracetamol (PAR) when compared to unmodified GCE. The morphology of the proposed sensor was characterized by scanning electron microscopy. The electrochemical characterization was performed by cyclic voltammetry and electrochemical impedance spectroscopy using the redox pair [Fe(CN)6]3−/4–. Using phosphate buffer solution (pH 7.0) and differential pulse voltammetry, DOP and PAR were determined simultaneously in the concentration range 0.099–2.9, and 0.70–19 μmol L–1, with limits of detection of 0.013, and 0.11 μmol L–1, respectively. The developed method with the fabricated electrochemical sensor is simple, fast, and sensitive. The proposed sensor was successfully applied to the individual and simultaneous determination of DOP and PAR in various samples, showing the practical feasibility of the proposed sensor as a novel platform for the sensitive determination of these phenolic compounds.

Effective adsorption of trace phosphate and aluminum in realistic water by carbon nanotubes and reduced graphene oxides

In this study, carbon nanotube (CNT) and reduced graphene oxide (rGO) were studied for their potentials as novel adsorbents for trace concentrations of phosphorus and aluminum in water and wastewater. Static adsorption results demonstrated that CNT and rGO employed in this study removed up to 65.6% of total dissolved Al and 98.9% of P from a natural surface water and a secondary wastewater effluent. Hydrogen-bonding interactions between CNT/rGO and oxyanions were hypothesized to contribute to the adsorption process. Accordingly, acetaminophen (AAP), a pharmaceutical compound known to form hydrogen bonding with CNT, was spiked into the real water as a competitor for P and Al adsorption. Subsequent sorption results showed that the presence of AAP reduced Al and P adsorption by CNT and rGO by 9.3%–18.4% and 11.2%–18.2%, respectively. These results suggest that hydrogen bonding interactions with CNT/rGO influenced the adsorption of P and Al species. In addition, pH effect investigation on Al/P removal further verified the above opinion. Overall, this study provided important evidence and insights into CNT/rGO adsorption of P and Al species from water and wastewater, which expanded our understanding on the ability of carbonaceous nanomaterials for advanced water and wastewater treatment.

Effects of carbonaceous nanomaterials on soil-grown soybeans under combined heat and insect stresses.

Because carbonaceous nanomaterials (CNMs) are expected to enter soils, the exposure implications to crop plants and plant-microbe interactions should be understood. Most investigations have been under ideal growth conditions, yet crops commonly experience abiotic and biotic stresses. Little is known how co-exposure to these environmental stresses and CNMs would cause combined effects on plants. We investigated the effects of 1000 mg kg-1 multiwalled carbon nanotubes (CNTs), graphene nanoplatelets (GNPs) and industrial carbon black (CB) on soybeans grown to the bean production stage in soil. Following seed sowing, plants became stressed by heat and infested with an insect (thrips). Consequently, all plants had similarly stunted growth, leaf damage, reduced final biomasses and fewer root nodules compared with healthy control soybeans previously grown without heat and thrips stresses. Thus, CNMs did not significantly influence the growth and yield of stressed soybeans, and the previously reported nodulation inhibition by CNMs was not specifically observed here. However, CNMs did significantly alter two leaf health indicators: the leaf chlorophyll a/b ratio, which was higher in the GNP treatment than in either the control (by 15 %) or CB treatment (by 14 %), and leaf lipid peroxidation, which was elevated in the CNT treatment compared with either the control (by 47 %) or GNP treatment (by 66 %). Overall, these results show that, while severe environmental stresses may impair plant production, CNMs (including CNTs and GNPs) in soil could additionally affect foliar health of an agriculturally important legume.

Self lubricating property of MWCNT in AA2219 composites during high energy ball milling

Abstract Revolutions in nanotechnology enabled the development of advanced nanocomposites with superior properties for engineering applications especially in automotive and aerospace industries. Among this carbonaceous nano materials like MWCNT have got more attention. Addition of MWCNT in metal matrix results in retardation of friction coefficient and improvement on other mechanical properties based on its dispersion. MWCNT won’t have sufficient space to occupy over the powder surface, when the addition is beyond a limit and acts as a solid lubricant during milling. Investigations on self lubricating property during milling were done by using scanning electron microscope, X-ray diffraction and powder density. Uniform dispersion was the bottleneck to utilize their attractive properties of the reinforcement. An attempt had been done for a uniform dispersion during premixing process using a combination of ultra-sonication, magnetic and mechanical stirring followed by high energy ball milling.

Pathomorphological pattern of the mouse lungs and liver after repeated intratracheal instillation with different carbonaceous nanomaterials

Pathomorphological pattern of the mouse lungs and liver after repeated intratracheal instillation with different carbonaceous nanomaterials

Nitrate reductase-dependent nitric oxide is crucial for multi-walled carbon nanotube-induced plant tolerance against salinity.

Although there have been some studies on the plant-carbonaceous nanomaterials (CNMs) interactions, related conclusions were controversial. Here, we report that multi-walled carbon nanotubes (MWCNTs) can enter into rapeseed (Brassica napus L.) seedling root, and transport to stem. Further results showed that salinity-inhibited rapeseed seedling growth was obviously alleviated by MWCNTs. Meanwhile, NaCl-induced nitrate reductase (NR)-dependent NO production was significantly intensified by MWCNTs. The redox and ion imbalance was reestablished as well, confirmed by the reduction in reactive oxygen species (ROS) overproduction, the decrease in thiobarbituric acid reactive substance production, and the lower Na+/K+ ratio. These beneficial effects could be explained by the changes in related antioxidant defense genes, sodium hydrogen exchanger 1 (NHX1), salt overly sensitive 1 (SOS1), and K+transporter 1 (KT1) transcripts. The above responses were separately abolished after the removal of endogenous NO with its scavengers or the addition of the NR inhibitor. Genetic evidence revealed that the NaCl-triggered NO level in wild-type seedling roots was partly abolished in either the nitric reductase mutant (nia1/2) or noa1 mutant (exhibiting indirectly a reduced endogenous NO level). Treatment with MWCNTs could totally rescue the impaired NO production in the noa1 mutant rather than the nia1/2 mutant, suggesting that NR-dependent NO acts as a downstream signaling molecule in MWCNT signaling. This point was verified by phenotypic analyses, histochemical staining, and ion analysis. qPCR analysis further demonstrated that MWCNTs stimulated antioxidant genes and ion balance-related genes through NR-mediated NO. The above molecular and genetic evidence indicated that NR-dependent NO acts downstream of MWCNTs in salinity tolerance, which requires the reestablishment of redox and ion homeostasis.