Evaluating the Impact of Seed Nano-Priming with Green-Synthesized Copper Oxide Nanoparticles Using Mimosa pigra Leaf Extract on the Germination and Seedling Growth of Tomato (Solanum lycopersicum)

Using plant extracts in the green synthesis of nanoparticles has become an environmentally acceptable approach. In our study, copper oxide nanoparticles (CuO NPs) were synthesized using ethanolic extracts of Azadirachta indica and Simmondsia chinensis. CuO NP formation was confirmed by the change in color and by UV‒visible spectroscopy (CuO NPs peaked at a wavelength of 344 nm). TEM images confirmed the semispherical shape of the CuO NPs, with particle sizes ranging from 30.9 to 10.7 nm. The antibacterial activity of these NPs was evaluated by using the agar diffusion method against clinical isolates, including methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa, Acinetobacter spp., Klebsiella pneumoniae, and Stenotrophomonas maltophilia. The minimum inhibitory concentration (MIC) of CuO NPs ranged from 62.5 to 125 µg/ml. In contrast, the antioxidant activity and antibiofilm activity of CuO NPs ranged from 31.1 to 92.2% at 125–500 µg/ml and 62.2–95%, respectively, at 125 –62.5 µg/ml. Our results confirmed that CuO NPs had IC50s of 383.41 ± 3.4 and 402.73 ± 1.86 at 250 µg/mL against the HBF4 cell line. Molecular docking studies with CuO NPs suggested that penicillin-binding protein 4 (PBP4) and beta-lactamase proteins (OXA-48) strongly bind to S. aureus and K. pneumoniae, respectively, with CuO NPs. Our study confirms the promising use of CuO NPs in treating pathogenic bacteria and that CuO NPs could be possible alternative antibiotics. This study supports the pharmaceutical and healthcare sectors in Egypt and worldwide.

Bacterial infections are one of the leading causes of death worldwide. In the case of topical bacterial infections such as wound infections, silver (Ag) has historically been one of the most widely used antibacterials. However, scientific publications have demonstrated the adverse effects of silver on human cells, ecotoxicity and insufficient antibacterial effect for the complete elimination of bacterial infections. The use of Ag in the form of nanoparticles (NPs, 1–100 nm) allows to control the release of antibacterial Ag ions but is still not sufficient to eliminate infection and avoid cytotoxicity. In this study, we tested the potency of differently functionalized copper oxide (CuO) NPs to enhance the antibacterial properties of Ag NPs. The antibacterial effect of the mixture of CuO NPs (CuO, CuO–NH2 and CuO–COOH NPs) with Ag NPs (uncoated and coated) was studied. CuO and Ag NP combinations were more efficient than Cu or Ag (NPs) alone against a wide range of bacteria, including antibiotic-resistant strains such as gram-negative Escherichia coli and Pseudomonas aeruginosa as well as gram-positive Staphylococcus aureus, Enterococcus faecalis and Streptococcus dysgalactiae. We showed that positively charged CuO NPs enhanced the antibacterial effect of Ag NPs up to 6 times. Notably, compared to the synergy of CuO and Ag NPs, the synergy of respective metal ions was low, suggesting that NP surface is required for the enhanced antibacterial effect. We also studied the mechanisms of synergy and showed that the production of Cu+ ions, faster dissolution of Ag+ from Ag NPs and lower binding of Ag+ by proteins of the incubation media in the presence of Cu2+ were the main mechanisms of the synergy. In summary, CuO and Ag NP combinations allowed increasing the antibacterial effect up to 6 times. Thus, using CuO and Ag NP combinations enables to retain excellent antibacterial effects due to Ag and synergy and enhances beneficial effects, since Cu is a vital microelement for human cells. Thus, we suggest using combinations of Ag and CuO NPs in antibacterial materials, such as wound care products, to increase the antibacterial effect of Ag, improve safety and prevent and cure topical bacterial infections.

Copper oxide nanoparticles (CuO NPs) have been extensively explored for use in agriculture. Previous studies have indicated that application of CuO NPs might be promising for development and conservation of plants, pest control, and for the recovery of degraded soils. However, depending on the applied concentration copper can cause phytotoxic effects. In this work, biosynthesized CuO NPs (using green tea extract) were evaluated on their effects on lettuce (Lactuca sativa L.) seedling growth, which were exposed at concentrations ranged between 0.2 and 300μgmL-1. From the biosynthesized were obtained ultra-small CuO NPs (~6.6nm), with high stability in aqueous suspension. Toxicity bioassays have shown that at low concentrations (up to 40μgmL-1), CuO NPs did not affect or even enhanced the seed germination. At higher concentrations (higher than 40μgmL-1), inhibition of seed germination and radicle growth ranging from 35 to 75% was observed. With the increase of CuO NPs concentrations, nitrite and S-nitrosothiols levels in radicles increased, whereas superoxide dismutase and total antioxidant activities decreased. The nitrite and S-nitrosothiols levels in lettuce radicles showed a direct dose response to CuO NP application, which may indicate nitric oxide-dependent signaling pathways in the plant responses. Therefore, the results demonstrated that at low concentrations (≤ 20μgmL-1) of CuO NPs, beneficial effects are obtained from seedlings, enhancing plant growth, and the involvement of nitric oxide signaling in the phytotoxic effects induced by high concentration of this formulation. Graphical abstract.

Objective: In this study, copper oxide nanoparticles are produced using the probiotic Saccharomyces boulardii in order to assess their biological activity. The biological method of producing nanoparticles is gaining popularity due to its benefits over chemical and physical ways of synthesis in terms of affordability and environmental friendliness. Methods: To biosynthesize CuO NPs, copper sulfate was introduced at a concentration to S. boulardii’s cell-free supernatant. Results: The color change of the reaction mixture from light to dark after 150 rpm incubation, as well as the color change and antibacterial behavior, were indicators of S. bularedii’s biosynthesis of CuO NPs. The characterization completed by UV-visible spectroscopy, Atomic force microscopy, Energy Dispersive Spectroscopy, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, and X-ray diffraction (AFM). The CuO NP absorption spectra in the reaction mixture’s UV-visible spectroscopy were (537.93 nm). The XRD showed that CuO NPs’ crystal size was (14.65 nm). The SEM was provided; the shape was uniform and spherical, and the average size (16.03 nm). EDS was used to analyze the presence of elemental CuO NPs. The CuO NPs’ three-dimensional structure was seen by the AFM, and their average diameter was (41.11 nm). The FTIR spectrum reveals a variety of functional groups that are present at various locations. Gram positive and gram negative bacteria that were isolated from diabetic foot infections were multidrug resistant (MDR), and biosynthesized CuO NPs demonstrated antibacterial action against these bacteria (Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Proteus mirabilis). In the form of biofilm using a microtiter plate and treated by nanoparticles, all of the examined bacterial isolates demonstrated their capacity to form biofilm. The harmful bacteria when treated with CuO NPs this capacity was inhibited and eradicated. The concentrations of CuO NPs (1 mg/ml, 0.5 mg/ml, 0.25 mg/ml, and 0.12 mg/ml) revealed their antioxidant activity in vitro by scavenging DPPH free radicals; the mixture of DPPH and biogenic CuO NPs at this concentration had the highest inhibition titer (72.44%).

This study investigated the potential of green-synthesized copper oxide nanoparticles (CuO NPs) to enhance biomass production and therapeutic metabolite yields in Alhagi maurorum, a medicinal plant of significant pharmaceutical value. CuO NPs were biosynthesized using A. maurorum leaf extract as a reducing and capping agent, with characterization confirmed via UV-Vis spectroscopy, FTIR, XRD, SEM, TEM, and zeta potential analysis. Nanoparticles ranged from 7-30 nm in size. Callus induction and proliferation were established using Murashige and Skoog (MS) media supplemented with varying concentrations (0-12 mg/L) of CuO NPs combined with plant growth regulators. Maximum callus fresh weight (9.02 mg in cotyledon and 8.46 mg in hypocotyl) was achieved in MS media containing 3.0 mg/L BAP, 0.1 mg/L NAA, and 0.50 mg/L kinetin without CuO NPs. However, CuO NPs significantly enhanced metabolite production in a dose-dependent manner. Analysis of variance revealed statistically significant differences (p=0.001) across all biochemical parameters tested, with high F-values for peroxidase activity (7,755.74), total flavonoids (5,195.02), and total soluble sugar (5,702.18). At 8 mg/L CuO NPs, callus cultures exhibited elevated levels of total free amino acids (12.49±0.023 mg/g DW) and total soluble protein (35.617±0.033 mg/g DW), while control samples produced higher starch (35.547±0.23 mg/g DW) and total soluble sugar (121.56±0.091 mg/g DW) content. Significantly, CuO NP-treated cultures demonstrated enhanced secondary metabolite synthesis, with maximum total phenolic compounds (156.477±0.167 mg/g DW GAE) and flavonoids (58.307±0.179 mg/g QE) at 8 and 10 mg/L CuO NPs, respectively. Antioxidant enzyme analysis revealed that cotyledon-derived callus exhibited peak activities at specific CuO NP concentrations: superoxide dismutase (84.5±0.254% inhibition) and glutathione reductase (0.75±0.006% inhibition) at 8 mg/L; peroxidase (3.137±0.009 U), catalase (77.35±0.152 U), and ascorbate peroxidase (0.43±0.006 mM/mg FW) at 10 mg/L. HPLC analysis confirmed the novel presence of lupeol, an anticancer compound, in regenerated roots. These findings demonstrate the potential of CuO NPs for enhancing therapeutic metabolite production in A. maurorum tissue culture while suggesting optimal concentration ranges (8-10 mg/L) for maximum benefits. Further research is necessary to elucidate the molecular mechanisms governing nanoparticle-plant interactions and to address potential health implications.

The synthesis of CuO NPs from Citrus fruit peel waste is a noteworthy strategy for the effective repurposing utilization of waste and its application in therapeutic studies. Synthesized copper oxide nanoparticles (CuO NPs) from citrus fruit extracts displayed a dark greenish-black colour with sizes ranging from 379.41, 113.19 and 142.76nm of lemon, orange and tangerine CuO NPs. Phytochemical screening confirmed the presence of phytochemicals in the extracts wherein lemon CuO NPs lacked flavonoids and cardiac glycosides, while orange CuO NPs lacked alkaloids and flavonoids, and tangerine CuO NPs lacked only alkaloids. The decrease in phenolic concentration in CuO NPs was attributed to complex formation with metal ions. Tangerine CuO NPs exhibited the highest antioxidant activity, while lemon CuO NPs showed the highest total antioxidant capacity. Antibacterial activity increased with CuO NP concentration, with tangerine CuO NPs displaying the highest activity against both Bacillus subtilis subtilis strain 168 and Escherichia coli strain PU-1 isolated from Ghagghar river, Haryana, India. This activity was linked to the disruption of bacterial cell membranes and oxidative stress, supported by the interaction between CuO NPs and bacterial cell components. These findings contribute to understanding of various potential applications of citrus fruit-derived CuO NPs in antimicrobial and antioxidant therapies.

Rice (Oryza sativa L.), a major staple food for billions of people, was assessed for its phytotoxicity of copper oxide nanoparticle (CuO NPs, size < 50 nm). Under hydroponic condition, seven days of exposure to 62.5, 125, and 250 mg/L CuO NPs significantly suppressed the growth rate of rice seedlings compared to both the control and the treatment of supernatant from 250 mg/L CuO NP suspensions. In addition, physiological indexes associated with antioxidants, including membrane damage and antioxidant enzyme activity, were also detected. Treatment with 250 mg/L CuO NPs significantly increased malondialdehyde (MDA) content and electrical conductivity of rice shoots by 83.4% and 67.0%, respectively. The activity of both catalase and superoxide dismutase decreased in rice leaves treated with CuO NPs at the concentration of 250 mg/L, while the activity of the superoxide dismutase significantly increased by 1.66 times in rice roots exposed to 125 mg/L CuO NPs. The chlorophyll, including chlorophyll a and chlorophyll b, and carotenoid content in rice leaves decreased with CuO NP exposure. Finally, to explain potential molecular mechanisms of chlorophyll variations, the expression of four related genes, namely, Magnesium chelatase D subunit, Chlorophyll synthase, Magnesium-protoporphyrin IX methyltransferase, and Chlorophyllide a oxygenase, were quantified by qRT-PCR. Overall, CuO NPs, especially at 250 mg/L concentration, could affect the growth and development of rice seedlings, probably through oxidative damage and disturbance of chlorophyll and carotenoid synthesis.

Nanoparticle contamination has been associated with adverse impacts on crop productivity. Thus, effective approaches are necessary to ameliorate NP-induced phytotoxicity. The present study aimed to investigate the efficacy of brassinosteroids and ethylene in regulating CuO NPs toxicity in rice seedlings. Therefore, we comprehensively evaluated the crosstalk of 24-Epibrassinolide and ethylene in regulating CuO NP-induced phytotoxicity at the physiological, cellular ultrastructural, and biochemical levels. The results of the study illustrated that exposure to CuO NPs at 450 mg/L displayed a significant decline in growth attributes and induced toxic effects in rice seedlings. Furthermore, the exogenous application of ethylene biosynthesis precursor 1-aminocyclopropane-1-carboxylic acid (ACC) at 20 µM with 450 mg/L of CuO NPs significantly enhanced the reactive oxygen species (ROS) accumulation that led to the stimulation of ultrastructural and stomatal damage and reduced antioxidant enzyme activities (CAT and APX) in rice tissues. On the contrary, it was noticed that 24-Epibrassinolide (BR) at 0.01 µM improved plant biomass and growth, restored cellular ultrastructure, and enhanced antioxidant enzyme activities (CAT and APX) under exposure to 450 mg/L of CuO NPs. In addition, brassinosteroids reduced ROS accumulation and the toxic effects of 450 mg/L of CuO NPs on guard cells and the stomatal aperture of rice seedlings. Interestingly, when 0.01 µM of brassinosteroids, 20 µM of ACC, and 450 mg/L of CuO NPs were applied together, BRs and ethylene showed antagonistic crosstalk under CuO NP stress via partially reducing the ethylene-induced CuO NP toxicity on plant growth, cellular ultrastructure, stomatal aperture, and guard cell and antioxidant enzyme activities (CAT and APX) in rice seedlings. BR supplementation with ACC and CuO NPs notably diminished ACC-induced CuO NPs’ toxic effects on all of the mentioned attributes in rice seedlings. This study uncovered the interesting crosstalk of two main phytohormones under CuO NPs stress, providing basic knowledge to improve crop yield and productivity in CuO NPs-contaminated areas.

Cytotoxicity and cellular mechanisms of toxicity of CuO NPs in mussel cells in vitro and comparative sensitivity with human cells

Aromatic plants as soil amendments: Effects of spearmint and sage on soil properties, growth and physiology of tomato seedlings

Genotoxic effects of copper oxide nanoparticles in Neuro 2A cell cultures

Here, we aim to disclose the role of two different ranges concentration of copper oxide nanoparticles (CuO NPs) for the adsorption of BSA to CuO NP surfaces and the kinetics of the energy transfer between CuO NPs and BSA molecule by using different spectroscopy, time-resolved fluorescence measurements, and DLS study. The grown ~ 20.31 nm CuO NPs showed 3.60-eV band gap and 1.026-eV Urbach energy. The XRD pattern showed that the unit cell of the synthesized CuO nano-crystal is monoclinic phase. The photoluminescence spectrum of pure CuO NPs showed a high quantum yield of the blue emission. A small red shift of the absorption peak of BSA is determined because of binding with CuO NPs. The calculated value of an apparent association constant (Kapp) in the CuO NPs–BSA bioconjugate was found to be 6.51 × 103 M−1 and 2.16 × 103 M−1 for the small concentration range and large concentration range, respectively. The total change in energy transfer efficiency (ΔEeff) at room temperature is 22% and 5.6% for the use large and small concentration, respectively; at body temperature, this change is 13.6% and 6.6%, respectively. The BSA quenching is a mixed type in lower temperature in the low-concentration range and fully dynamic in the high-concentration range. The nature of interaction is exothermic, electrostatic, and hydrophobic. The fluorescence lifetimes of pure BSA decreased from 4.94 to 1.04 ns upon adsorption onto CuO NPs, corresponding to Eeff of 79.35%. The use of large concentration leads to aggregation rather than individual corona formation under the small concentration of CuO NPs.

The eco-friendly method of producing copperـoxide nanoparticles through the use of okra fruit extract is a simple, economical, rapid, and sustainable technique. The resultant copperـoxide nanoparticles (CuO NP) were analyzed with several analytical methods, such as UV-vis spectroscopy, FourierـTransform Infrared Spectroscopy (FT-IR), and X-Ray Diffraction (XRD), Zeta potential, TransmissionـElectron Microscopy (TEM) and EnergyـDispersive X-ray (EDX) analysis. The CuO NP exhibited a maximum absorbance at 381 nm. The formation of CuO NP was further confirmed by characteristic bands observed at 534 and 588 cm-1. The monoclinic structure of the CuO NP was identified with prominent peaks detected at 2θ values of 32.47°, 35.43°, 38.64°, 48.68°, 53.38°, 58.14°, 61.39°, 66.11°, 67.82°, 72.27°, and 74.96°. The overall findings indicate that the nanoparticles had an average diameter in the approximate range of 10 to 30 nm based on the TEM analysis. The cytotoxicity study, conducted on Human Fibroblast normal HFB4 cell lines, indicated that the halfـmaximal inhibitory concentration (IC50) dose was 236.34 μg/mL. An IC50 dose of 109.46 μg/mL was found in antitumor effect studies using breast adenocarcinoma Mcf- 7 cell lines, revealing a good level of safety for CuO NP. According to the antibacterial study, Staphylococcus aureus and Bacillus cereus had inhibition zone diameters (IZDs) of 29.5 ± 0.7 mm and 24.6 ± 1.2 mm, respectively, making them the most vulnerable bacteria to CuO NP. In contrast, P. aeruginosa was the least sensitive strain, with a minimum IZD of 15 ± 1.6 mm. Compared to gram-negative infections, the CuO NPs were found to have a significantly higher antibacterial effectiveness versus Gram -positive pathogens. Molecular docking against dihydrofolate reductase (DHFR) of Staphylococcus aureus (PDB ID: 6P9Z) illustrated that the CuO NP was partially interlocked with the active site of 6P9Z by the fitting energy value of -44.93 kcal/mol through five classical hydrogen bonds with Ala7, Gln9, Thr46, Ser49, and Phe92. The last one is also generated by the marketing antifolate agent methotrexate (MTX), adding some MTX-like character to the CuO NP inhibitor.

Uptake and toxicity of CuO nanoparticles to Daphnia magna varies between indirect dietary and direct waterborne exposures

Copper oxide nanoparticles (CuO NPs) are widely used as catalysts or semiconductors in material fields. Recent studies have suggested that CuO NPs have adverse genotoxicity and cytotoxicity effects on various cells. However, little is known about the toxicity of CuO NPs following exposure to murine lungs. The purpose of this fundamental research was to investigate whether CuO NPs could induce epithelial cell injury, pulmonary inflammation, and eventually fibrosis in C57BL/6 mice. Our studies showed that CuO NPs aggravated pulmonary inflammation in a dose-dependent manner. CuO NPs induced apoptosis of epithelial cells as indicated by TUNEL staining, flow cytometry and western blot analysis, which was partially caused by increased reactive oxygen species (ROS). In addition, CuO NPs exposure promoted collagen accumulation and expression of the progressive fibrosis marker α-SMA in the lung tissues, indicating that CuO NP inhalation could induce pulmonary fibrosis in C57BL/6 mice. All data provide novel evidence that there is an urgent need to prevent the adverse effects of CuO NPs in the human respiratory system.