Size-dependent biological effect of copper oxide nanoparticles exposure on cucumber (Cucumis sativus)

Harnessing the potential of copper-based nanoparticles in mitigating abiotic and biotic stresses in crops

The demand for crops production continues to intensify with the rapid increase in population. Agricultural crops continue to encounter abiotic and biotic stresses, which can substantially hamper their productivity. Numerous strategies have been focused to tackle the abiotic and biotic stress factors in various plants. Nanotechnology has displayed great potential to minimize the phytotoxic impacts of these environmental constraints. Copper (Cu)-based nanoparticles (NPs) have displayed beneficial effects on plant growth and stress tolerance. Cu-based NPs alone or in combination with plant growth hormones or microorganisms have been documented to induce plant tolerance and mitigate abiotic or biotic stresses in different plants. In this review, we have comprehensively discussed the uptake and translocation of Cu-based NPs in plants, and beneficial roles in improving the plant growth and development at various growth stages. Moreover, we have discussed how Cu-based NPs mechanistically modulate the physiological, biochemical, metabolic, cellular, and metabolic functions to enhance plant tolerance against both biotic (viruses, bacterial and fungal diseases, etc.) and abiotic stresses (heavy metals or metalloids, salt, and drought stress, etc.). We elucidated recent advancements, knowledge gaps, and recommendations for future research. This review would help plant and soil scientists to adapt Cu-based novel strategies such as nanofertilizers and nanopesticides to detoxify the abiotic or biotic stresses. These outcomes may contribute to the promotion of healthy food production and food security, thus providing new avenues for sustainable agriculture production.

Copper oxide nanoparticles mitigate cadmium toxicity in rice seedlings through multiple physiological mechanisms

Heavy metal pollution poses a serious threat to crops growth and yield. Recently, nanoparticles (NPs) have emerged as a promising strategy to mitigate the negative effect of heavy metal on crop growth. This study investigated the beneficial effects of copper oxide nanoparticles (CuO NPs) on the morphological and physiological-biochemical traits of rice seedlings (Oryza sativa L.) under cadmium (Cd) stress. The results demonstrated that the application of CuO NPs increased the contents of nutrition elements in shoots and roots as well as photosynthetic pigments, consequently improving the growth of rice seedlings under Cd stress, especially at low level of Cd stress. Meanwhile, CuO NPs obviously decreased the Cd accumulation in the rice seedlings and immobilized Cd in less toxic chemical forms and subcellular compartments. Moreover, CuO NPs modulated the antioxidant system, ameliorating oxidative damage and membrane injury caused by Cd. Multivariate analysis established correlations between physio-biochemical parameters and further revealed the mitigation of Cd damage to rice seedlings by CuO NPs was associated with inhibition Cd accumulation, altering Cd chemical form and subcellular distribution, increasing the contents of mineral nutrients, photosynthetic pigments and secondary metabolites and antioxidant enzyme activities, and reducing oxidative damage. Overall, the present study indicated that CuO NPs could effectively reduce the Cd toxicity to rice seedlings, demonstrating their potential application in agricultural production.

Particle morphology and soil properties affect the retention of copper oxide nanoparticles in agricultural soils

The interaction between nanoscale copper oxides (nano-CuOs) and soil matrix significantly affects their fate and transport in soils. This study investigates the retention of nano-CuOs and Cu2+ ions in ten typical agricultural soils by employing the Freundlich adsorption model. Retention of nano-CuOs and Cu2+ in soils was well fitted by the Freundlich model. The retention parameters (KD, KF, and N) followed an order of CuO NTs > CuO NPs > Cu2+, highlighting significant impact of nano-CuOs morphology. The KF and N values of CuO NPs/Cu2+ were positively correlated with soil pH and electrical conductivity (EC), but exhibited a weaker correlation for CuO NTs. Soil pH and/or EC could be used to predict KF and N values of CuO NPs or CuO NTs, with additional clay content should be included for Cu2+.The different relationship between retention parameters and soil properties may suggest that CuO NTs retention mainly caused by agglomeration, whereas adsorption and agglomeration were of equal importance to CuO NPs. The amendment of Ca2+ at low and medium concentration promoted retention of nano-CuOs in alkaline soils, but reduced at high concentration. These findings provided critical insights into the fate of nano-CuOs in soil environments, with significant implications for environmental risk assessment and soil remediation strategies.

Recent advances on environmental behavior of Cu-based nanomaterials in soil-plant system: A review

In recent years, copper-based nanomaterials (Cu-based NMs) have shown great potential in promoting agriculture development due to their special physicochemical characteristics. With the mass production and overuse of Cu-based NMs, there are potential effects on the soil-plant environment. Soil organisms, especially soil microorganisms, play a significant part in terrestrial or soil ecosystems; plants, as indirect organisms with soil-related Cu-based NMs, may affect human health through plant agricultural products. Understanding the accumulation and transformation of Cu-based NMs in soil-plant systems, as well as their ecotoxicological effects and potential mechanisms, is a prerequisite for the scientific assessment of environmental risks and safe application. Therefore, based on the current literature, this review: (i) introduces the accumulation and transformation behaviors of Cu-based NMs in soil and plant systems; (ii) focuses on the ecotoxicological effects of Cu-based NMs on a variety of organisms (microorganisms, invertebrates, and plants); (iii) reveals their corresponding toxicity mechanisms. It appears from studies hitherto made that both Cu-based NMs and released Cu2+ may be the main reasons for toxicity. When Cu-based NMs enter the soil-plant environment, their intrinsic physicochemical properties, along with various environmental factors, could also affect their transport, transformation, and biotoxicity. Therefore, we should push for intensifying the multi-approach research that focuses on the behaviors of Cu-based NMs in terrestrial exposure environments, and mitigates their toxicity to ensure the promotion of Cu-based NMs.

Metallic nanoparticles and photosynthesis organisms: Comprehensive review from the ecological perspective

This review presents a comprehensive analysis of the ecological implications of metallic nanoparticles (MNPs) on photosynthetic organisms, particularly plants and algae. We delve into the toxicological impacts of various MNPs, including gold, silver, copper-based, zinc oxide, and titanium dioxide nanoparticles, elucidating their effects on the growth and health of these organisms. The article also summarizes the toxicity mechanisms of these nanoparticles in plants and algae from previous research, providing insight into the cellular and molecular interactions that underpin these effects. Furthermore, it discusses the reciprocal interactions between different types of MNPs, their combined effects with other metal contaminants, and compares the toxicity between MNPs with their counterpart. This review highlights the urgent need for a deeper understanding of the environmental impact, considering their escalating use and the potential risks they pose to ecological systems, especially in the context of photosynthetic organisms that are vital to ecosystem health and stability.

Size Effects of Copper Oxide Nanoparticles on Boosting Soybean Growth via Differentially Modulating Nitrogen Assimilation

Nanoscale agrochemicals have been widely used in sustainable agriculture and may potentially affect the nitrogen fixation process in legume crops. The present study investigated the size-effects of copper oxide nanoparticles (CuO NPs) on nitrogen assimilation in soybean (G. max (L.) Merrill) plants, which were treated with different sizes (20 and 50 nm) of CuO NPs at low use doses (1 and 10 mg/kg) for 21 days under greenhouse conditions. The results showed that 50 nm CuO NPs significantly increased the fresh biomass more than 20 nm CuO NPs achieved at 10 mg/kg. The activities of N assimilation-associated enzymes and the contents of nitrogenous compounds, including nitrates, proteins, and amino acids, in soybean tissues were greatly increased across all the CuO NP treatments. The use doses of two sizes of CuO NPs had no impact on the Cu contents in shoots and roots but indeed increased the Cu contents in soils in a dose-dependent fashion. Overall, our findings demonstrated that both 20 and 50 nm CuO NPs could positively alter soybean growth and boost N assimilation, furthering our understanding that the application of nanoscale micro-nutrient-related agrochemicals at an optimal size and dose will greatly contribute to increasing the yield and quality of crops.

Bioavailability and Toxicity of nano Copper Oxide to Pakchoi (Brassica Campestris L.) as Compared with bulk Copper Oxide and Ionic Copper

The increasing use of copper oxide nano particles (nCuO) as nano-fertilizers and pesticides have raised concerns over their impact on soil environment and agricultural products. In this study, two nCuO with different shapes, namely spherical nCuO (CuO NPs) and tubular nCuO (CuO NTs), were selected to investigate their bioavailability and toxicity to pakchoi in two soils with different properties. At the meantime, CuO bulk particles (CuO BPs) and Cu(NO3)2 were used for comparison. Results showed that all the Cu treatments increased the DTPA extractable (DTPA-Cu) concentrations in GD soil (acidic) more than in HN soil (alkaline). The DTPA-Cu concentrations increased in the order of Cu(NO3)2 ≈ CuO NPs > CuO BPs ≈ CuO NTs in GD soil and Cu(NO3)2 > CuO NPs > CuO BPs ≈ CuO NTs in HN soil. While for the contents of Cu in the aerial parts of pakchoi, the order is CuO NPs > Cu(NO3)2 > CuO NTs ≈ CuO BPs in GD soil and CuO NPs ≈ Cu(NO3)2 > CuO BPs ≈ CuO NTs in HN soil. Only CuO NPs reduced pakchoi biomass in GD soil. There are no significant difference among CuO NPs, CuO BPs, and Cu(NO3)2 in reducing the chlorophyll contents in pakchoi in HN soil, whereas in GD soil, CuO NPs and CuO BPs led to significantly lower chlorophyll contents in pakchoi compared to Cu(NO3)2. Additionally, CuO NPs and Cu(NO3)2 increased Mn and Mo in pakchoi leaf in HN soil, while increased Zn in pakchoi leaf in GD soil. These results indicated that CuO NPs showed higher or comparable toxicity and bioavailability to pakchoi compared with Cu(NO3)2 depending on soil properties, and nCuO are more easily to be transferred from roots to the aerial parts than CuO BPs and Cu(NO3)2.

Analysis of multiple biomarkers revealed the size matters of Cu particles for barley response under foliar exposure

The impact of particle size of engineered nanoparticles (ENPs) on plant response has marginally been investigated under the foliar application so far. Concerning the significance of particle diameter for their properties and interaction with plants, the effect of size should be considered in the analysis of the effect of micronutrient-based ENPs on plants. It is of particular importance for ENPs containing Cu due to plants needing a relatively low amount of this element, thus there is a risk of overdosing during application as a fertilizer or pesticide. Here, we examined the biochemical and transcriptional response of barley (Hordeum vulgare L.) to Cu nanoparticles (nano-Cu) with different diameters (25 nm, 50 nm, 70 nm), microparticles (micro-Cu), and chelated Cu (EDTA-Cu). The plants suffering from Cu deficiency were foliar sprayed with Cu compounds at 1000 mg/L during the tillering stage. 1- and 7-day plants were analyzed in terms of biomass, Cu content, the activity of enzymes involved with antioxidant response, the content of low molecular weight compounds, and the expression of genes regulated metal homeostasis, aquaporins, and defense. The results showed that the Cu leaf level was differentiated over time and after 7 days it was higher under exposure to the smallest nano-Cu than other particulate Cu. Regardless of the duration of exposure, the Cu content was highest in plants treated with Cu-EDTA. The cluster analysis of all markers revealed a clear distinct response to the smallest nano-Cu and other particulate and ionic treatments. The bigger nano-Cu, depending on the markers, caused the medium effects between the nano-Cu 25 nm and micro-Cu and Cu-EDTA. The found size thresholds at the nanoscale will be useful for the fabrication of safe-by-design agrochemicals to provide crop security and attenuate environmental impact.

Synthesis and characterization of CeO2 and SiO2 nanoparticles and their effect on growth parameters and the antioxidant defense system in Vigna mungo L. Hepper

Engineered nanoparticles (NPs) have recently attracted a lot of attention after being tested in various agricultural plants. This paper reports the green synthesis of CeO2 NPs and SiO2 NPs from leaf extracts of Nyctanthes arbor-tristis. The physical characteristics of the produced nanoparticles were then determined using UV-visible spectroscopy, transmission electron microscopy (TEM), fluorescence spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Furthermore, the interaction effects of cerium oxide NPs (C1, C2, and C3) and silicon dioxide NPs (S1, S2, and S3) at 10 mg/L on blackgram (Vigna mungo L.) were evaluated. CeO2 and SiO2 NPs treatments enhanced the growth performance of the plants by causing a decrease in superoxide radical (SOR) and H2O2 via improving antioxidant enzymes. These findings imply that the size and shape of CeO2 and SiO2 NPs provide defense against oxidative damage to the blackgram.

Recent Advances and Perspectives of Nanomaterials in Agricultural Management and Associated Environmental Risk: A Review

The advancement in nanotechnology has enabled a significant expansion in agricultural production. Agri-nanotechnology is an emerging discipline where nanotechnological methods provide diverse nanomaterials (NMs) such as nanopesticides, nanoherbicides, nanofertilizers and different nanoforms of agrochemicals for agricultural management. Applications of nanofabricated products can potentially improve the shelf life, stability, bioavailability, safety and environmental sustainability of active ingredients for sustained release. Nanoscale modification of bulk or surface properties bears tremendous potential for effective enhancement of agricultural productivity. As NMs improve the tolerance mechanisms of the plants under stressful conditions, they are considered as effective and promising tools to overcome the constraints in sustainable agricultural production. For their exceptional qualities and usages, nano-enabled products are developed and enforced, along with agriculture, in diverse sectors. The rampant usage of NMs increases their release into the environment. Once incorporated into the environment, NMs may threaten the stability and function of biological systems. Nanotechnology is a newly emerging technology, so the evaluation of the associated environmental risk is pivotal. This review emphasizes the current approach to NMs synthesis, their application in agriculture, interaction with plant-soil microbes and environmental challenges to address future applications in maintaining a sustainable environment.