Dose-Dependent Effect of Foliar ZnO Nanoparticles on the Physiology, Mineral Nutrition, and Redox Status of Coffea arabica Seedlings Under Soil Acidity

In the last few decades use of metal-based nanoparticles (MNPs) has been increased significantly that eventually contaminating agricultural land and limiting crop production worldwide. Moreover, contamination of food chain with MNPs has appeared as a matter of public concern due to risk of potential health hazard. Brassinosteroid has been shown to play a critical role in alleviating heavy metal stress; however, its function in relieving zinc oxide nanoparticles (ZnO NPs)-induced phytotoxicity remains unknown. In this study, we investigated the potential role of 24-epibrassinolide (BR) in mitigating ZnO NPs-induced toxicity in tomato seedlings. Seedling growth, biomass production, and root activity gradually decreased, but Zn accumulation increased with increasing ZnO NPs concentration (10–100 mg/L) in growth media (½ MS). The augmentation of BR (5 nM) in media significantly ameliorated 50 mg/L ZnO NPs-induced growth inhibition. Visualization of hydrogen peroxide (H2O2), and quantification of H2O2 and malondialdehyde (MDA) in tomato roots confirmed that ZnO NPs induced an oxidative stress. However, combined treatment with BR and ZnO NPs remarkably reduced concentration of H2O2 and MDA as compared with ZnO NPs only treatment, indicating that BR supplementation substantially reduced oxidative stress. Furthermore, the activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase, ascorbate peroxidase and glutathione reductase were increased by combined treatment of BR and ZnO NPs compared with ZnO NPs only treatment. BR also increased reduced glutathione (GSH), but decreased oxidized glutathione (GSSG)] and thus improved cellular redox homeostasis by increasing GSH:GSSG ratio. The changes in relative transcript abundance of corresponding antioxidant genes such as Cu/Zn SOD, CAT1, GSH1, and GR1 were in accordance with the changes in those antioxidants under different treatments. More importantly, combined application of BR and ZnO NPs significantly decreased Zn content in both shoot and root of tomato seedlings as compared with ZnO NPs alone. Taken together, this study, for the first time, showed that BR could not only improve plant tolerance to ZnO NPs but also reduce the excess zinc content in tomato seedlings. Such a finding may have potential implication in safe vegetable production in the MNPs-polluted areas.

The widespread use of zinc oxide nanoparticles (ZnO NPs) has resulted in their release to the environment. There has been concern about the ecotoxicity of ZnO NPs, but little is known about their toxic mechanisms. In the present study, we conducted acute toxicity tests to show that ZnO NPs are more toxic to the freshwater crustacean Daphnia pulex compared to bulk ZnO or ZnSO4·7H2O. To provide an integrated and quantitative insights into the toxicity of ZnO NPs, we conducted isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis, which detected 262, 331, and 360 differentially expressed proteins (DEPs) in D. pulex exposed to ZnO NPs, bulk ZnO, and ZnSO4·7H2O, respectively. Among the DEPs, 224 were shared among the three treatments. These proteins were related to energy metabolism, oxidative stress, and endoplasmic reticulum stress. The three forms of Zn all caused D. pulex to downregulate Chitinase expression, disrupt Ca2+ homeostasis, and reduce expression of digestive enzymes. Nevertheless, 29 proteins were expressed only in the ZnO NP treatment. In particular, histone (H3) and ribosomal proteins (L13) were obviously influenced under ZnO NP treatment. However, increased expression levels of h3 and l13 genes were not induced only in ZnO NP treatment, they were sensitive to Zn ions under the same exposure concentration. These results indicate that the three zinc substances have a similar mode of action and that released zinc ions are the main contributor to ZnO NP toxicity to D. pulex under a low concentration. Further investigation is needed to clarify whether a small proportion of DEPs or higher bioavailability cause ZnO NPs to be more toxic compared to bulk ZnO or ionic zinc.

Salt stress is an abiotic stressor that adversely affects the growth and productivity of caraway, an important aromatic plant. A randomized complete split-plot design was used to determine the nanoparticles of zinc oxide (ZnO NPs) effects at levels of 0, 0.2, and 0.4 g L-1 on fruit yield, chemical and biochemical composition, and essential oil (EO) productivity of caraway plants subjected to saline irrigation water containing 0, 1, 2, 3, and 4 g L-1 sodium chloride (NaCl). The results indicated that increasing NaCl concentrations significantly reduced yield traits, relative water content, salinity tolerance index, leaf pigment concentrations, N, P, K, and Zn concentrations, fruits’ total proteins and total carbohydrates and percentage and yield/plant of essential oil (EO) in comparison to the untreated plants. Conversely, proline content, Na% and Cl%, and the activities of catalase, peroxidase, superoxide dismutase, and polyphenol oxidase increased with increasing NaCl concentrations relative to the control. Foliar application of ZnO NPs significantly increased the parameters relative to the untreated control except proline content, Na%, and Cl%, which were in comparison to respective control significantly reduced. Moreover, utilization of ZnO NPs positively affected the traits mentioned above under all NaCl concentrations tested compared to treatments without ZnO NPs. Different combinations of NaCl and ZnO NPs concentrations had varying effects on EO composition. A total of 32 compounds were identified across all treatment combinations, with the highest number (14) observed in the control. The major EO compounds were carvone (up to 49.71%) in the 2 g L-1 NaCl + 0.2 g L-1 ZnO NPs treatment, limonene (up to 28.68%) in the 2 g L-1 NaCl + 0.4 g L-1 ZnO NPs treatment, and D-limonene (up to 25.95%) in the 4 g L-1 NaCl + 0 g L-1 ZnO NPs treatment. These results suggest that the application of ZnO NPs may provide a sustainable approach to caraway cultivation under saline conditions.

Soil contamination with chromium (Cr) is becoming a primary ecological and health concern, specifically in the Kasur and Sialkot regions of Pakistan. The main objective of the current study was to evaluate the impact of foliar application of zinc oxide nanoparticles (ZnO NPs) (0, 25, 50, 100 mg L−1) and Fe NPs (0, 5, 10, 20 mg L−1) in red sails lettuce plants grown in Cr-contaminated soil. Our results showed that both ZnO and Fe NPs improved plant growth, and photosynthetic attributes by minimizing oxidative stress in lettuce plants through the stimulation of antioxidant enzyme activities. At ZnO NPs (100 mgL−1), dry weights of shoots and roots and fresh weights of shoots and roots were improved by 53%, 58%, 34%, and 45%, respectively, as compared to the respective control plants. The Fe NPs treatment (20 mgL−1) increased the dry weight of shoots and the roots and fresh weights of shoots and roots by 53%, 76%, 42%, and 70%, respectively. Application of both NPs reduced the oxidative stress caused by Cr, as evident by the findings of the current study, i.e., at the ZnO NPs (100 mgL−1) and Fe NPs (20 mgL−1), the EL declined by 32% and 44%, respectively, in comparison with respective control plants. Moreover, Fe and ZnO NPs enhanced the Fe and Zn contents in red sails lettuce plants. Application of ZnO NPs at 100 mg L−1 and Fe NPs at 20 mg L−1, improved the Zn and Fe contents in plant leaves by 86%, and 68%, respectively, as compared to the control plants. This showed that the exogenous application of these NPs helped in Zn and Fe fortification in plants. At similar of concenteration ZnO NPs, CAT and APX activities were improved by 52% and 53%, respectively. Similarly, the POD contents were improved by 17% and 45% at 5 and 10 mg/L of Fe NPs. Furthermore, ZnO and Fe NPs limited the Cr uptake by plants, and the concentration of Cr in the leaves of lettuce was under the threshold limit. The exogenous application of ZnO NPs (100 mg L−1) and Fe NPs (20 mg L−1) reduced the Cr uptake in the leaves of red sails lettuce by 57% and 51%, respectively. In conclusion, ZnO and Fe NPs could be used for the improvement of plant growth and biomass as well as nutrient fortification in stressed environments. These findings not only underscore the efficacy of nanoparticle-assisted phytoremediation but also highlight its broader implications for sustainable agriculture and environmental health. However, future studies on other crops with molecular-level investigations are recommended for the validation of the results.

Zinc oxide nanoparticles (ZnO NPs) exhibit diverse applications, including antimicrobial, UV-blocking, and catalytic properties, due to their unique structure and properties. This study focused on the characterization of zinc oxide nanoparticles (ZnO NPs) synthesized from Juglans regia leaves and their application in mitigating the impact of simultaneous infection by Meloidogyne arenaria (root-knot nematode) and Macrophomina phaseolina (root-rot fungus) in cowpea plants. The characterization of ZnO NPs was carried out through various analytical techniques, including UV–visible spectrophotometry, Powder-XRD analysis, FT-IR spectroscopy, and SEM-EDX analysis. The study confirmed the successful synthesis of ZnO NPs with a hexagonal wurtzite structure and exceptional purity. Under in vitro conditions, ZnO NPs exhibited significant nematicidal and antifungal activities. The mortality of M. arenaria juveniles increased with rising ZnO NP concentrations, and a similar trend was observed in the inhibition of M. phaseolina mycelial growth. SEM studies revealed physical damage to nematodes and structural distortions in fungal hyphae due to ZnO NP treatment. In infected cowpea plants, ZnO NPs significantly improved plant growth parameters, including plant length, fresh mass, and dry mass, especially at higher concentrations. Leghemoglobin content and the number of root nodules also increased after ZnO NP treatment. Additionally, ZnO NPs reduced gall formation and egg mass production by M. arenaria nematodes and effectively inhibited the growth of M. phaseolina in the roots. Furthermore, histochemical analyses demonstrated a reduction in oxidative stress, as indicated by decreased levels of reactive oxygen species (ROS) and lipid peroxidation in ZnO NP-treated plants. These findings highlight the potential of green-synthesized ZnO NPs as an eco-friendly and effective solution to manage disease complex in cowpea caused by simultaneous nematode and fungal infections.

Nutrient strengthening of winter wheat by foliar ZnO and Fe3O4 NPs: Food safety, quality, elemental distribution and effects on soil bacteria

The effects of three preservation methods (ultrasound, ZnO NPs, and ultrasound combined with ZnO NPs) on the odor, microstructure, and edible quality of fresh-cut lettuce were investigated in this study. When stored for 8 days, significant improvements were observed in the following when using ultrasound combined with ZnO NP treatment to better preserve fresh-cut lettuce (and were reduced when compared with the control group): the color (L* value (34.53); a* value (−5.89); b* value (15.00); browning index (40.63); firmness (25.66); propectin (2.12%); chlorophyll (2.75 mg/100 g); cellulose (20.35%); total phenolic content (0.95 mg/100 g); PAL activity (54.91 U·h−1·g−1); CAT activity (41.78 U·min−1·mg−1); ABTS free-radical scavenging ability (137.62 µmol/L); FRAP total reducing ability (94.42 µmol/L) (p < 0.05), PPO activity (0.85 U·min−1·g−1); MDA (1.97 µmol/g); and H2O2 (54.26 µmol/g). In addition, the results of the volatile components indicated that the use of ultrasound combined with ZnO NP treatment decreased the production of adverse flavor compounds by inhibiting the generation of aldehydes and ketones, as well as by promoting the generation of olefins, nitriles, and quinolines, and the contents of nitriles and quinolines were 20.07% and 2.07% of the total components, respectively. The resultant microstructure indicated that the microchannels generated by ultrasound allowed for the ZnO NPs to enter the intracellular cavity of the fresh-cut lettuce more efficiently; such a finding could serve as a basis for a hypothesis on the mechanism of ultrasound combined with ZnO NP treatment. The results of fresh-cut lettuce preservation when using ultrasound combined with ZnO NPs were better than those that were obtained when using ultrasound and ZnO NP treatment alone. And, using ultrasound combined with ZnO NP treatment as a new preservation method for fresh-cut lettuce provides a promising preservation idea for other fresh-cut fruits and vegetables.

Soil salinization severely restricts the growth and development of crops globally, especially in the northwest Loess Plateau, where apples constitute a pillar industry. Nanomaterials, leveraging their unique properties, can facilitate the transport of nutrients to crops, thereby enhancing plant growth and development under stress conditions. To investigate the effects of nano zinc oxide (ZnO NP) on the growth and physiological characteristics of apple self-rooted rootstock M9-T337 seedlings under saline alkali stress, one-year-old M9-T337 seedlings were used as experimental materials and ZnO NPs were used as donors for pot experiment. Six treatments were set up: CK (normal growth), SA (saline alkali stress,100 mmol/L NaCl + NaHCO3), T1 (saline alkali stress + 50 mg/L ZnO NPs), T2 (saline alkali stress + 100 mg/L ZnO NPs), T3 (saline alkali stress + 150 mg/L ZnO NPs) and T4 (saline alkali stress + 200 mg/L ZnO NPs). The results were found to show that saline alkali stress could significantly inhibit the growth and development of M9-T337 seedlings, reduce photosynthetic characteristics, and cause ion accumulation to trigger osmotic regulation system, endogenous hormone and antioxidant system imbalances. However, the biomass, plant height, stem diameter, total leaf area and leaf perimeter of M9-T337 seedlings were significantly increased after ZnO NP treatment. Specifically speaking, ZnO NPs can improve the photosynthetic capacity of M9-T337 by increasing the content of photosynthetic pigment, regulating photosynthetic intensity and chlorophyll fluorescence parameters. ZnO NPs can balance the osmotic adjustment system by increasing the contents of soluble protein (SP), soluble sugar (SS), proline (Pro) and starch, and can also enhance the activities of enzymatic (SOD, POD, and CAT) and non-enzymatic antioxidant enzymes (APX, AAO, GR, and MDHAR) to enhance the scavenging ability of reactive oxygen species (H2O2, O2•-), ultimately reducing oxidative damage; ZnO NPs promoted the growth of M9-T337 seedlings under saline alkali stress by synergistically responding to auxin (IAA), gibberellin (GA3), zeatin (ZT) and abscisic acid (ABA). Additionally, the Na+/K+ ratio was reduced by upregulating the expression of Na+ transporter genes (MdCAX5, MdCHX15, MdSOS1, and MdALT1) and downregulating the expression of K+ transporter genes (MdSKOR and MdNHX4). After comprehensive analysis of principal components and correlation, T3 (150 mg/L ZnO NPs) treatment possessed the best mitigation effect. In summary, 150 mg/L ZnO NPs(T3) can effectively maintain the hormone balance, osmotic balance and ion balance of plant cells by promoting the photosynthetic capacity of M9-T337 seedlings, and enhance the antioxidant defense mechanism, thereby improving the saline alkaline tolerance of M9-T337 seedlings.

Previous studies recorded positive impact of ZnO NPs on plants stressed with salinity. The current work was performed to study the effect of two different concentrations of biosynthesized ZnO NPs (50 and 100 mg L−1) on faba bean plants under salinity stress. The zinc oxide nanoparticles (ZnO NPs) were synthesized using Mentha extract, and their shape and size were characterized using X-ray diffraction and transmission electron microscope while diffuse reflectance spectra were measured using UV–Vis spectrophotometer. The generated ZnO NPs were spherical with a particle size 9.4 nm and had a rod form with particle size 15.2 in length and 3.5 nm in width. The response of faba been plants to the foliar spray of ZnO NPs concentrations (0, 50, and 100 mg L−1) alone and in combination with salt stress at 150 mM NaCl was studied. Salinity induced reduction in faba bean root and shoot length and dry/fresh weights, while an enhancement was recorded in response to foliar treatment with ZnO NPs at 50 and 100 mg L−1 either in presence or absence of salinity stress. The highest amounts of chlorophyll a, b, carotenoids, and total pigments were recorded in plants received 50 mg L−1 ZnO NPs compared to the alternative control. Secondary metabolites (phenols, flavonoids, and tannins) were accumulated in salinity-stressed plants and further accumulation in response to ZnO NPs treatment was noticed. Amino acids, proline, glycine betaine, and total soluble sugars, as well as enzymatic and non-enzymatic antioxidant contents, increased almost onefold in salinity-stressed plants as compared to control plants while the 50 mg L−1 ZnO NPs treatment resulted in higher accumulation of the previously mentioned substances. In contrast, plants oxidative stress was reduced in response to ZnO NPs treatments. The nitrogen, phosphorus, potassium, calcium, zinc, and iron contents of faba bean plants were recorded under salinity stress and in response to the two applied concentrations of ZnO NPs. Faba bean plants stressed with 150 MN NaCl showed growth decline that may be attributed to osmotic stress and low water availability imposed by salinity. The treatment of stressed plants with 50 mg L−1 ZnO NPs induced an enhancement in plant growth as well as an accumulation of antioxidants, osmolytes, and secondary metabolites that could help plants overcome the negative effects of salinity.

In the present study, toxicity of commercial zinc oxide nanoparticles (ZnO NPs) was studied on the bacterium Pseudomonas sp., human promyelocytic leukemia (HL-60) cells, and peripheral blood mononuclear cells (PBMC). The toxicity was assessed by measuring growth, cell viability, and protein expression in bacterial cell. The bacterial growth and viability decreased with increasing concentrations of ZnO NP. Three major proteins, ribosomal protein L1 and L9 along with alkyl hydroperoxides reductase, were upregulated by 1.5-, 1.7-, and 2.0-fold, respectively, after ZnO NP exposure. The results indicated oxidative stress as the leading cause of toxic effect in bacteria. In HL-60 cells, cytotoxic and genotoxic effects along with antioxidant enzyme activity and reactive oxygen species (ROS) generation were studied upon ZnO NP treatment. ZnO NP exhibited dose-dependent increase in cell death after 24-h exposure. The DNA-damaging potential of ZnO NP in HL-60 cells was maximum at 0.05mg/L concentration. Comet assay showed 70-80% increase in tail DNA at 0.025 to 0.05mg/L ZnO NP concentration. A significant increase of 1.6-, 1.4-, and 2.0-fold in ROS level was observed after 12h. Genotoxic potential of ZnO NPs was also demonstrated in PBMC through DNA fragmentation. Thus, ZnO NP, besides being an essential element having antibacterial activity, also showed toxicity towards human cells (HL-60 and PBMC).

More than 90% of spermatozoa of boars in pork producing countries is stored in liquid at 17 °C; however, the quality of these spermatozoa is affected by bacterial breeding and oxidative damage. This study analyzed sperm quality and sperm capacitation after storage to study the effects of the effects of ZnO nanoparticles (ZnO NPs) supplementation on seminal plasma (SP)-free sperm preservation. We investigated the effects of adding 20, 50, 100 and 200 μg/mL of ZnO NPs to a seminal free boar sperm diluent over a 7-day period at 17 °C to assess the changes in non-capacitated/capacitated sperm quality parameters, antioxidant capacity, ATP content and extent of protein tyrosine phosphorylation. The addition of different doses of ZnO NPs to stored sperm did not induce significant effects on the sperm motility and ATP content when compared to the sperm without ZnO NPs treatment. However, the addition of 50, 100, 200 μg/mL ZnO NPs to stored sperm improved total antioxidant capacity (T-AOC) and CuZn-superoxide dismutase (CuZn-SOD) (p < 0.05). ZnO NPs also reduced the malondialdehyde (MDA) content of the preserved sperm (p < 0.05). Moreover, our results indicate that the supplementation of 50 μg/mL ZnO NPs to preserved sperm improved the sperm membrane integrity (p < 0.05). ZnO NPs exerted protective effects on protein tyrosine phosphorylation, especially with regards to membrane proteins. Following incubation and capacitation, sperm exhibited good levels of protein tyrosine phosphorylation and ATP levels with high T-AOC and CuZn-SOD activity and low MDA content. ZnO NPs exerted protective capacity to a preservation extender used for SP-free boar sperm during storage at 17 °C. The optimal concentration of ZnO NPs for preservation extender was 50 μg/mL.

This study aimed to assess the apoptosis-inducing mechanism of zinc oxide nanoparticles (ZnO NPs) stabilized by Solanum xanthocarpum plant extract in human osteosarcoma MG63 cells. In the present study, we synthesized ZnO NPs from S. xanthocarpum extract and evaluated its anticancer mechanism on MG 63 cells. The synthesized ZnO NPs were characterized by ultraviolet spectroscopy, X-ray crystallography, transmission electron microscopy, energy dispersive X-ray, and Fourier-transform infrared spectroscopy analysis. The mean size of the synthesized ZnO NPs was 21.62 ± 7.45 nm and spherical in shape. The cytotoxicity of ZnO NPs on MG63 cells was determined by MTT assay. The Western blot analysis was carried out to examine the expression of apoptotic and autophagy-related proteins in MG63 cells. The findings of the study reveal that ZnO NPs treatment showed concentration-dependent cytotoxicity, increased lipid peroxidation, decreased antioxidant activity, increased reactive oxygen species generation, and increased DNA damage. In addition, ZnO NPs treatment increased the expression of apoptotic members such as p53, Bax, caspase-3, -8, and -9 while downregulating Bcl-2 expression in MG63 cells. Furthermore, ZnO NPs treatment suppressed the P13K/AKT/mTOR signaling pathway and increased the expression of LC3 and beclin-1 in MG63 cells. The present study demonstrated that ZnO NPs induced apoptosis and autophagy in MG63 cells through modifying apoptotic and autophagy-related proteins.

The application of zinc oxide nanoparticles: An effective strategy to protect rice from rice blast and abiotic stresses

Glycine betaine capped ZnO NPs eliminate oxidative stress to coriander plants grown under NaCl presence

Recently, many biological fields including medicine, personal care products, sunscreens and food additives, also many industrial domains such as ceramics, rubber, paints and alloys, have been extensively applied by Zinc oxide nanoparticles (ZnO NPs), as it has the ability to pass through the cell membrane easily and even pass through blood-brain barrier. They are highly reactive and may cause oxidative stress, which induces serious damages in DNA and protein structures forming mutation. So, the current study was designed to assess the possible mitigating effect of Artemisia judaica (Art. j.), vitamin C (vit. C) or their co-administration against ZnO NPs–induced hepatorenal toxicity in male rats. Eighty adult male rats were divided into 8 groups: the 1st (control group) with distilled water for 45 days; the 2nd (twin 80 group) with twin 80 for 45 days; the 3rd (ZnO NPs group), rats were gavaged daily with 10 mg/kg body weight (b.wt) of ZnO NPs for 15 days; the 4th (vit. C group), rats were gavaged daily with 100 mg/kg b.wt of vit. C for 30 days; the 5th (Art. j. group), rats were gavaged daily with 150 mg/kg b.wt of Art. j. extract for 30 days; the 6th (ZnO NPs + vit. C group), rats were gavaged daily with 10 mg/kg b.wt of ZnO NPs for 15 days then gavaged daily with 100 mg/kg b.wt of vit. C for 30 days; the 7th (ZnO NPs + Art. j. group), rats were gavaged daily with 10 mg/kg b.wt of ZnO NPs for 15 days then gavaged daily with 150 mg/kg b.wt of Art. j. for 30 days; the 8th (ZnO NPs + vit. C and Art. j. group), rats were gavaged daily with 10 mg/kg b.wt of ZnO NPs for 15 days then gavaged daily with Art. j. and vit. C co-administration for 30 days. ZnO NPs group showed a high significant increase in serum alanine aminotransferase (ALT), aspartate amino transferase (AST), alkaline phosphatase enzyme (ALP) and gamma glutamyltransferase(GGT) activities, serum total and direct bilirubin, creatinine, urea and uric acid levels, and blood urea nitrogen (BUN) and malondialdhyde (MDA) levels. While, it showed a high significant decrease in serum albumin, protein and reduced glutathione (GSH) levels, serum superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) activities, as well as blood hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs) and packed cell volume (PCV) as compared with control group. ZnO NPs groups that were treated by vit. C or Art. j. showed partial ameliorative effect against ZnO NPs-induced hepatorenal toxicity with convergent degree, but the efficacy of Art.j. was better than vit. C. ZnO NPs group that was treated by vit. C and Art. j. co-administration showed marked significant curative effects against ZnO NPs- induced hepatorenal toxicity.