CuO ZnO Research Articles

Synthesis and anti-microbial investigations of CZ6 composite reinforced CA mixed matrix membranes

In order to design cellulose acetate (CA) membranes for exceptional antifungal and antibacterial activity an idiosyncratic filler CuO–ZnO (1:6) coded as CZ6 has synthesized employing sol-gel method to integrate into CA matrix. Solution mixing followed by thermally assisted evaporation process (TAEP) is adopted for membranes synthesis. FESEM delineate filler particle size within 20 nm and membranes’ pores size changed from 1.6 nm to 1.4 nm with the varying filler ratios i.e., 2.5, 5-10 wt% to CA content. The crystallographic study elucidates the average crystallite size of CZ6 is 20 nm and confirms its presence in the host matrix. FTIR detected respective functional groups of functionalized CZ6 composite. TGA proclaims addition of filler improved thermal endurability of CA membranes. All prepared membranes are tested against Aspergillus fungus and E. coli bacteria, employing microbial culture methods. Results proclaim strong performance of CZ6 reinforced CA membranes as anti-microbial assay and can be recommended as best antimicrobial membranes.

Rational design of ZnO–CuO–Au S-scheme heterojunctions for photocatalytic hydrogen production under visible light

An integration of S-scheme heterojunction catalyst with surface plasmon resonance effect is the prime focus of current research activites in the field of visible light driven photocatalytic hydrogen (H2) evolution. Herein, a sol-gel route is used to design a heterojunction of ZnO–CuO–Au. The effect of process parameters, including irradiation time, catalyst dose, and sacrificial reagents on the hydrogen evolution is studied. The S-scheme ZnO–CuO–Au heterojunction catalyst demonstrated high surface area, better optical absorption response in the visible part of light spectrum, and improved separation and transportion of charge carriers as verified by DRS, PL, and photoelectrochemical studies. The maximum H2 evolution rateof ZnO–CuO–Au reaches 4655 μmolh−1g−1, which is 5 and 3.2 times higher than ZnO–CuO and Au–ZnO catalysts, respectively. A possible reason of this increase in H2 evolution rate is inhibited recombination of charge carriers because of the S-scheme design to increase electrons with strong reduction potential and prolong lifetime, Au serves as an SPR source and conductive channel to swift the transfer of electrons and high density of active sites. This work offers innovative insight into designing plasmonic metals-modified S-scheme systems for solar fuel production.

Comparison study on ZnO and CuO gas sensing characteristics: Temperature modulated-dual selectivity towards benzene and xylene vapours

The selective detection of gaseous benzene, toluene, ethylbenzene, and xylene (BTEX) is challenging due to their similar molecular structures. In addition, BTEX vapours are extremely hazardous and carcinogenic. Thus, in the current study, n-type ZnO and p-type CuO nanostructures were synthesized utilizing various bases by a simple hydrothermal method. Among the tested sensors, the ZnO–NaOH-based sensor displayed a temperature dual-mode selectivity toward benzene with responses (Ra/Rg) of 2.5 and 24 at 5 and 100 ppm, respectively at 75 °C, and Ra/Rg ≈ 142 toward xylene vapour at 100 ppm at an operating temperature of 150 °C. While the CuO-based sensors showed poor response, sensitivity and selectivity towards tested analytes. Moreover, the ZnO–NaOH based sensor revealed enormous sensitivity of 1.21 ppm−1 and low limit of detection (LoD) of 0.018 ppm (i.e., 18 ppb) toward xylene. The ultra-sensitivity, selectivity, low LoD of ZnO–NaOH based sensor toward benzene and xylene are associated with the improved VO observed in the in-situ photoluminescence and electron paramagnetic resonance studies, and as well as the x-ray photoelectron spectroscopy analyses. The ZnO–NaOH-based sensor, which was stored for roughly 18 months (547 days), demonstrated a reliable repeatability and long-time operation stability for 22 h exposure to xylene. The superior sensitivity, stability, and selectivity indicate openly that the strategy of using various bases is a striking method for fabricating a temperature dual-mode selectivity for the detection of benzene and xylene vapours.

Surface conversion of CuO–ZnO to ZIF-8 to enhance CO2adsorption for CO2hydrogenation to methanol

A novel CuO–ZnO@ZIF-8 catalyst with abundant oxygen vacancies and high CO2adsorption capacity is synthesized for converting CO2into CH3OH. Compared to the traditional CuO–ZnO catalyst, the catalyst in this work significantly improves the conversion and selectivity.

Developing efficient CuO nanoplate/ZnO nanoparticle hybrid photocatalysts for methylene blue degradation under visible light.

CuO/ZnO nanocomposites with different components can overcome the drawbacks of previously used photocatalysts owing to their promotion in charge separation and transportation, light absorption, and the photo-oxidation of dyes. In this study, CuO nanoplates were synthesized by the hydrothermal method, while ZnO nanoparticles were fabricated by the precipitation method. A series of CuO/ZnO nanocomposites with different ZnO-to-CuO weight ratios, namely, 2 : 8, 4 : 6, 5 : 5, 6 : 4, and 8 : 2 were obtained via a mixing process. X-ray diffraction patterns confirmed the presence of hexagonal wurtzite ZnO and monoclinic CuO in the synthesized CuO/ZnO nanocomposites. Scanning electron microscopy showed the dispersion of ZnO nanoparticles on the surface of CuO nanoplates. Ultraviolet-visible absorption spectra exhibited a slight red-shift in the absorption edge of binary oxides relative to pure ZnO or CuO. All samples were employed for the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The composite samples exhibited enhanced photocatalytic performance compared with pristine CuO or ZnO. This study aimed to examine the effect of the ZnO-to-CuO weight ratio on their photocatalytic performance. The results indicated that among all the synthesized nanocomposites and pristine oxides, the nanocomposite with ZnO and CuO in a proportion of 4 : 6 shows the highest photodegradation activity for the removal of MB with 93% MB photodegraded within 60 min at an initial MB concentration of 5 ppm. The photocatalytic kinetic data were described well by the pseudo-first-order model with a high correlation coefficient of 0.95. The photocatalytic mechanism of the mixed metal oxide was proposed and discussed in detail. The photodegradation characteristic of CuO/ZnO nanostructures is valuable for methylene blue degradation from aqueous solutions as well as environmental purification in various fields.

Enhanced catalytic activity of ZnO–CuO–Co3O4 composites achieved using a mechanochemical method for effective Fenton-like dye removal: the generation and catalytic mechanism of various superficial active sites

Mechanochemical treatment for ZnO–Co3O4–CuO composites boosted their catalysis in the Fenton-like degradation of organic wastewater through exposing active oxygen vacancies and Cu/Co–O dangling bonds.

Synthesis of three-component Cu2O/ZnO/Ag nanocrystal heterogeneous photocatalysts with high reactivity and stability for dye reduction

Cu2O–ZnO–AgNC nanocrystals can suppress the photocorrosion of Cu2O and ZnO by efficiently utilizing the “active charges” for Congo red reduction. Furthermore, the plasmonic “hot electrons” from AgNC can be used to accelerate the reduction rate.

Sensitivity Enhancement of Resistive Ethanol Gas Sensor by Optimized Sputtered-Assisted CuO Decoration of ZnO Nanorods.

In this study, sputtered-assisted CuO-decorated ZnO nanorod (NR) gas sensors were fabricated for ethanol gas sensing studies. CuO nanoparticles have been successfully formed on ZnO nanorods by means of a physical process as the decorative metallic element. The amount of decoration affecting the sensor's performance has been optimized. Cu layers with different thicknesses of 5, 10, and 20 nm were deposited on hydrothermally grown ZnO NRs using the sputtering technique. Upon subsequent annealing, Cu was oxidized to CuO. The gas sensing studies revealed that the sensor with an initial Cu layer of 5 nm had the highest response to ethanol at 350 °C. The sensor also showed good selectivity, repeatability, and long-term stability. The enhanced ethanol sensing response of the optimized gas sensor is related to the formation of p-n heterojunction between p-type CuO and n-type ZnO and the presence of the optimal amount of CuO on the surface of ZnO NRs. The results presented in this study highlight the need for optimizing the amount of Cu deposition on the surface of ZnO NRs in order to achieve the highest response to ethanol gas.

Coupling ZnO with CuO for efficient organic pollutant removal.

Fabrication of heterojunction semiconductors for the photodegradation of toxic organic dyes under sunlight exposure has earned significant recognition from researchers nowadays. On that account, we have synthesized and explored a comparative photodegradation study of ZnO/CuO nanocomposite with ZnO and CuO nanoparticles. ZnO and CuO nanoparticles have been synthesized by biosynthesis methods usingFicus benghalensisleaf extract. As-synthesized ZnO and CuO nanoparticles have been further utilized for the synthesis of ZnO/CuO nanocomposite by the mortar pestle crushing/milling method. Both biosynthesis methods and mortar pestle crushing/milling methods are simple, low-cost, and environmentally friendly. Structural, optical, and morphological analysis of all the synthesized nanomaterials havebeen doneby powder X-ray diffraction (PXRD), scanning electron microscopy (SEM),transmission electron microscopy (TEM),Brunauer-Emmett-Teller (BET),field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy.PXRD data reveal that synthesized ZnO nanoparticles are in the hexagonal wurtzite phase, CuO nanoparticles in the monoclinic phase, and ZnO/CuO nanocomposite in the hexagonal wurtzite as well as in monoclinic phase. FE-SEM and TEM images of ZnO/CuO nanocomposite reveal the nanorod-shaped morphology along with micro-sized and nano-sized flakes. The BET analysis shows the surface areas 18.128 m2/g for ZnO nanoparticles, 16.653 m2/g for CuO nanoparticles, and 19.580 m2/g for ZnO/CuO nanocomposite, respectively. Theenergyband gap values of ZnO/CuO nanocomposite are obtained 3.13eV for ZnO and 2.76eV for CuO, respectively. The photocatalytic behaviors of all the synthesized nanomaterialsareexamined against aqueous dye solutions of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) under sunlight irradiation. The results reveal that the photocatalytic degradation efficiency of ZnO/CuO nanocompositehasbeen found higher than with ZnO and CuO nanoparticles for all the dyes. Also, all the synthesized nanomaterialsindicatehigher photocatalytic degradation efficiency for methylene blue dye among allthreedyes. The kinetics of photodegradation of all the dye solutions has also been investigated in the presence of ZnO, CuO, and ZnO/CuO photocatalysts separately. The results exhibit that rate constant values for all the dyes are higher with ZnO/CuOnanocompositethan with ZnO and CuOnanoparticles.ZnO/CuO nanocomposite demonstrates degradation efficiency for MB dye99.13%, for RhB80.21%, and for MO67.22%after 180min of sunlight exposure.ZnO/CuO nanocomposite and ZnO and CuO nanoparticles also show thebestreusability and stability up to three cycles for photocatalytic degradation of MB dyes amongall the dyes.Therefore, green synthesized ZnO/CuO nanocomposite could be used asan efficientphotocatalyst for the degradation of various toxic dyes.The mineralization of different dyes using ZnO/CuO nanocomposite has been examined by FTIR analysis. Furthermore, the mineralizationof MB dye has been done by total organic carbon (TOC)measurements.

Direct synthesis of CuO–ZnO–CeO2 catalyst on Al2O3/cordierite monolith for methanol steam reforming

Methanol steam reforming (MSR) is a promising process for in-situ hydrogen production in vehicles. However, designing monolithic catalysts with high activity and selectivity as well as low pressure drop remains a challenge. In this work, CuO–ZnO–CeO2 catalysts were prepared directly on Al2O3/cordierite monolith through a sol-gel combustion method, and the effects of different combustion temperatures on the physicochemical properties and catalytic performance of the catalysts were investigated. It is demonstrated that the catalyst (CZC-400) prepared by combustion temperature at 400 °C is uniformly distributed on the Al2O3/cordierite monolith with smaller average catalyst particle size (4.2 nm) and higher specific surface area (23.7 m2 g−1). In the MSR, methanol conversion of CZC-400 reaches 100% at 260 °C without by-product CO. Furthermore, no significant change in the catalytic activity is observed during 32 h of the reaction. These results indicate that CZC-400 has the excellent catalytic activity and stability in the MSR.

Toward Scaling up the Production of Metal Oxide Nanoparticles for Application on Washable Antimicrobial Cotton Fabrics.

To examine the utilization of metal oxide nanoparticles (NPs) in different commercial products, this work focuses on the determination of cost-effective and scalable synthesis protocols. The solvothermal protocol is well-known as a scalable method but has recently been shown to lack economic feasibility. The mechanochemical method has recently been recognized to be a more economic and environmentally friendly substitute for the solvothermal method. In this study, zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs) were synthesized using two (aqueous and organic) solvothermal (wet) methods and two (manual and automated) mechanochemical (dry) methods. The four methods were evaluated and compared. The automated mechanochemical method generated a significantly higher yield of ZnO NPs (82%) and CuO NPs (84%) using the least energy and time. However, the prepared ZnO NPs displayed higher cytotoxicity against Vero E6 cells when compared to that of CuO NPs. Because of their low cytotoxicity, CuO NPs synthesized via the automated mechanochemical method were selected for application onto cotton fabrics. Lower cytotoxicity was observed for CuO NPs treated fabrics with an IC50 of 562 mg/mL and ZnO treated fabrics with an IC50 at 23.93 mg/mL when the treated fabrics were tested against L929 fibroblast cells. Additionally, the cotton fabrics retained bactericidal and virucidal effects after four washes. Thus, the current study recommends the automated mechanochemical method as a cost-effective scalable approach for the synthesis of CuO NPs. The application of CuO NPs onto cotton fabrics generated washable antimicrobial face masks.

Generation of mesoporous n-p-n (ZnO–CuO–CeO2) heterojunction for highly efficient photodegradation of micro-organic pollutants

In this research, a mesoporous rod-shaped ZnO/CuO/CeO2 n-p-n heterojunction has been designed via a two-step co-precipitation technique for photocatalytic applications. Characterization by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), UV–Vis, and Scanning Electron Microscopy (SEM) techniques confirmed the formation of mesoporous rod-shaped ZnO/CuO/CeO2 n-p-n heterojunction having preferred interface developing between the ZnO, CuO, and CeO2 phases, thus extended the light-absorption window up to 800 nm. Under sunlight, the ability of a mesoporous ZnO/CuO/CeO2 n-p-n heterojunction to act as a photocatalyst was tested with methyl orange (MO) and crystal violet (CV) as target molecules. We found the degradation efficiencies of CV and MO dyes on mesoporous ZnO/CuO/CeO2 to be 96% and 88%, respectively, after 90 min of sunlight irradiation. The estimated rate constants (k, min−1) for deterioration of CV and MO under sunlight over ZnO/CuO/CeO2 composite were 0.039 and 0.022 min−1, respectively. We endorsed the greater photo-response, the well-aligned band-structure, and practical usage of the photo-induced carriers of the mesoporous photocatalyst to be the leading causes for the outstanding photocatalytic properties of ZnO/CuO/CeO2 n-p-n heterojunction. The ultimate oxidizing species that destroyed dyes were O2‾ and ·OH over ZnO/CuO/CeO2 photocatalyst under sunlight illumination. Besides, the recycling tests confirmed the high photostability of the ZnO/CuO/CeO2 photocatalyst. Hopefully, the mesoporous rod-shaped architecture of the n-p-n heterojunction with anticipated interface manufacturing will assist the photocatalyst strategy with better photocatalytic action under sunlight irradiation.

Simultaneous determination of four antibiotics in human urine and hair samples employing a simple and efficient dispersive micro solid-phase extraction-high performance liquid chromatography.

Antibiotics containing azithromycin, amoxicillin, doxycycline, tetracycline, and azithromycin are widely utilized in the treatment of bacterial infections, and their determination in biological samples is critical to evaluate their side effects. A dispersive micro solid-phase extraction (DMSPE) as an efficient sample preparation was developed for the simultaneous extraction of the antibiotics in biological samples. For this purpose, chitosan@Fe3O4 nanoparticles were prepared as a green and magnetic sorbent based on a chemical coating of Fe3O4 nanoparticles with chitosan. The sorbent was compared with several sorbents such as ZnO NPs, CuO NPs, and Fe3O4 NPs to extract the antibiotics. In addition, effective factors for antibiotic extraction were evaluated and optimized using a central composite design and one factor at a time. The method has wide linearity in the concentration ranges of 2.1-800.0, 3.5-1000.0, 2.0-800.0, and 2.7-1000.0μgL-1 with an R-squared higher than 0.9958 for the determination of azithromycin, amoxicillin, doxycycline, and tetracycline, respectively. The limit of detection and limit of quantitation was lower than 1.1 and 3.5μgL-1, respectively. The relative standard deviations (RSDs) were also lower than 4.90% for the determination of the analytes at a concentration of 20.0µgL-1. High recoveries in the percentage range of 94.70-106.75%, with RSDs between 4.64 and 5.83%, were obtained to analyze spiked urine and hair samples. The DMSPE-HPLC-DAD procedure displayed various advantages for determining antibiotics, including simple operation, high recoveries, low sample solution and desorption solvent consumption, high preconcentration factors, proper determination time, and simple and inexpensive method of sorbent preparation.

Modification of a Z-scheme ZnO-CuO nanocomposite by Ag loading as a highly efficient visible light photocatalyst

This paper has conducted a comparative study between ZnO-CuO and ZnO-CuO-Ag nanocomposites from a characterization and photodegradation mechanism point of view. The photocatalysts with different CuO contents and Ag loadings were synthesized through a quick and convenient co-precipitation method. The microstructural analysis showed the ZnO nanorods and CuO quasi-spherical formation with uniform distribution and proper contact, while Ag induced morphological changes to aggregation of spherical nanoparticles. X-ray photoelectron spectroscopy (XPS) proved the presence of metallic Ag (Ag0) in the Ag-loaded samples. 5 mol.% Ag loading in the ZnO-7.5 mol.%CuO nanocomposite increased band gap energy from 2.85 to 2.94 eV. Significant PL (photoluminescence) intensity reduction was observed by compositing 7.5 mol.% CuO, whereas Ag loading did not cause notable change. Among various prepared nanocomposites, the ZnO-7.5 mol.%CuO with 5 mol.% Ag loading was found to be the most influential with almost complete photodegradation efficiency toward methylene blue (MB) after 90 min under visible light irradiation. Both ZnO-CuO and ZnO-CuO-Ag nanocomposites exhibited a Z-scheme mechanism for charge transfer proposed based on the radical scavenging experiments. Superoxide radicals were the main active species participating in photocatalytic reactions. The loaded Ag acted as an electron mediator and improved the charge separation efficiency in the ZnO-CuO-Ag nanocomposite. The recycling of the nanocomposite was evaluated and the results showed a reusable photocatalyst with high stability for environmental wastewater purification.

Novel ternary CuO–ZnO–MoS2 composite material for electrochemical CO2 reduction to alcohols

Electrochemical reduction of CO2 with high selectivity for alcohol production has been considered as a proper way to address both energy catastrophe and environmental complications around the globe. Herein, two metal oxides, namely CuO and ZnO having great potential to catalyze the CO2 reduction, are chosen to form a composite with MoS2, where MoS2 sheets act as support and enhance electrocatalytic properties of CuO–ZnO due to their synergistic effect. The synthesis and characterizations of the tricomponent CuO–ZnO–MoS2 composite material is reported for the first time in this work. The composite possessed outstanding catalytic performance in CO2 reduction to alcohol in terms of extraordinary current density (121 mA/cm2) and low onset potential (−0.23 V vs RHE). The composite material showed maximum faradaic efficiency of 24.6% and 11.1% for methanol and ethanol at −0.6 V and −0.9 V vs RHE, respectively.

Effect of ZnO and CuO nanoparticles on the growth, nutrient absorption, and potential health risk of the seasonal vegetable Medicago polymorpha L.

BackgroundMedicago polymorpha L., a seasonal vegetable, is commonly grown in China. The increasing use of nanoparticles (NPs) such as ZnO and CuO NPs in agriculture has raised concerns about their potential risks for plant growth and for human consumption. There is a lack of research on the effects of ZnO and CuO NPs on agronomic performance of Medicago polymorpha L. and their potential risks for human health.MethodsIn this study, different treatment concentrations of ZnO NPs (25, 50, 100, and 200 mg kg−1) and CuO NPs (10, 25, 50, and 100 mg kg−1) were used to determine their effects on the growth and nutrient absorption of Medicago polymorpha L., as well as their potential risk for human health.ResultsThe results showed that ZnO and CuO NPs increased the fresh weight of Medicago polymorpha L. by 5.8–11.8 and 3.7–8.1%, respectively. The best performance for ZnO NPs occurred between 25–50 mg kg−1 and the best performance for CuO NPs occurred between 10–25 mg kg−1. Compared with the control, ZnO and CuO NPs improved the macronutrients phosphorus (P), potassium (K), magnesium (Mg), and calcium (Ca). The following micronutrients were also improved: iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), and manganese (Mn), with the exception of nitrogen (N) accumulation. Low treatment concentrations exhibited more efficient nutrient uptake than high treatment concentrations. A comprehensive analysis showed that the optimum concentrations were 25 mg kg−1 for ZnO NPs and 10 mg kg−1 for CuO NPs. The potential non-carcinogenic health risk of Medicago polymorpha L. treated with ZnO and CuO NPs was analyzed according to the estimated daily intake (EDI), the hazard quotient (HQ), and the cumulative hazard quotient (CHQ). Compared with the oral reference dose, the EDI under different ZnO and CuO NPs treatments was lower. The HQ and CHQ under different ZnO and CuO NPs treatments were far below 1. This indicated that Medicago polymorpha L. treated with ZnO and CuO NPs did not pose any non-carcinogenic health risk to the human body. Therefore, ZnO and CuO NPs were considered as a safe nano fertilizer for Medicago polymorpha L. production according to growth analysis and a human health risk assessment.

Dielectric and impedance studies of binary ZnO–CuO nanocomposites for hydroelectric cell application

Nanocomposites of xZnO-(1-x)CuO (x = 0.39, 0.69, 0.85) were synthesized using conventional solid state reaction method. The structural, dielectric and impedance properties of ZnO–CuO nanocomposites have been comprehensively studied. The X-ray diffraction studies show that the crystallite size decreases from 47 nm to 35 nm from 0.85ZnO-0.15CuO to 0.39ZnO-0.61CuO along with lowering of lattice parameter of ZnO–CuO on account of improved crystallinity. The UV–Vis spectroscopy display increase in bandgap with increasing CuO content in the nanocomposites. The dielectric constant in ZnO–CuO nanocomposites is found to improve strongly with CuO content in ZnO–CuO nanocomposites and apprise existence of non-Debye relaxation process. The dielectric loss decreases from 10 to nearly unit value due to increased crystallinity. The impedance spectroscopy analysis indicated the dielectric relaxation to be of poly-dispersive non-Debye type with dominant grain boundary contribution in the ZnO–CuO nanocomposite. The hydroelectric cells of ZnO–CuO nanocomposites exhibited enhanced performance with CuO content on account of improved ionic diffusion. The 0.69ZnO-0,31CuO nanocomposites displayed a constant current of 0.46 mA sustained for up to 3 h. These results make ZnO–CuO nanocomposites suitable for microelectronic and hydroelectric cell applications.

Green Synthesis of a CuO-ZnO Nanocomposite for Efficient Photodegradation of Methylene Blue and Reduction of 4-Nitrophenol.

CuO–ZnO nanocomposites (NCs) were synthesized using an aqueous extract of Verbascum sinaiticum Benth. (GH) plant. X-ray diffraction (XRD), spectroscopic, and microscopic methods were used to explore the crystallinity, optical properties, morphology, and other features of the CuO–ZnO samples. Furthermore, catalytic performances were investigated for methylene blue (MB) degradation and 4-nitrophenol (4-NP) reduction. According to the results, CuO–ZnO NCs with 20 wt % CuO showed enhanced photocatalytic activity against MB dye with a 0.017 min–1 rate constant compared to 0.0027 min–1 for ZnO nanoparticles (NPs). Similarly, a ratio constant of 5.925 min–1 g–1 4-NP reductions was achieved with CuO–ZnO NCs. The results signified enhanced performance of CuO–ZnO NCs relative to ZnO NPs. The enhancement could be due to the synergy between ZnO and CuO, resulting in improved absorption of visible light and reduced electron–hole (e–/h+) recombination rate. In addition, variations in the CuO content affected the performance of the CuO–ZnO NCs. Thus, the CuO–ZnO NCs prepared using V. sinaiticum Benth. extract could make the material a desirable catalyst for the elimination of organic pollutants.

Multioxide-superoxide dismutase enzyme-nanocomplexes and their antioxidant activity

Growth of bionanotechnology requires functional materials, which can lower the costs and can be modified to the specific reaction. Conjugations of nanoparticles and enzymes form efficient products of multi-material enzyme-nanocomplexes, which can be controlled from synthesis to application and can provide predicted results. Multimetallic nanooxides of ZnO–CuO, ZnO–MnO, ZnO–MnO–CuO were obtained by precipitation method with sonication, followed by microwave process. Superoxide dismutase (SOD) was immobilized on the surface of the nanoparticles. Obtained nanomaterial-enzyme complexes had antioxidant properties. Particles were characterised by XRD, SEM and TEM methods and ATR spectroscopy which proved enzyme-nanooxides conjugation. Scavenging activity of the materials was on average 85% in DPPH (2,2-diphenyl-1-picrylhydrazyl) method and 20 mg/l in TROLOX (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) concentration, where pure SOD enzyme presented around 90% and 10 mg/l activity, respectively. Conjugation of the highest antioxidant power is ZnO–MnO with SOD, however all three types of materials could be used in further applications.Graphical abstract

Clue of zinc oxide and copper oxide nanoparticles in the remediation of cadmium toxicity in Phaseolus vulgaris L. via the modulation of antioxidant and redox systems.

The present study represents new evidence of the successful use of metal oxide nanoparticles in the remediation of heavy metals. Zinc oxide nanoparticles (ZnO NP) and copper oxide nanoparticles (CuO NP) were assessed to alleviate cadmium (Cd) toxicity in Phaseolus vulgaris L. seedlings and plants. Monitoring physiological and metabolic parameters allowed to elucidate Cd mechanism and process whereby it exerts phytotoxic effects on bean. The response of P. vulgaris seedlings is NP dose-dependent (10 mg/L, 50 mg/L, 100 mg/L, and 200 mg/L). Similarly, applied concentrations triggered a differential response of growing plants in terms of length and biomass. Our physiological data allowed to select 100 mg/L as the most appropriate concentration to apply, in order to avoid any risk of phytotoxicity. The regulatory mechanisms by which ZnO NP and CuO NP act are for the first time compared in the embryonic axes of bean seedlings under Cd stress. Both NP were able to reduce the hypergeneration of hydrogen peroxide (H2O2). They also acted via enhancing ROS scavenging enzymatic capacity, and activity of antioxidant enzymes CAT, APX, GPOX, GPX, and GR, and inhibited the activity of ROS producing enzymes such as GOX and NOX. Another mechanistic effect of NP consisted of the modulation of redox enzymes Trx, NTR, Fd, and FNR evolved in cellular homeostasis and maintaining reduced status in cells. Taken together, ZnO NP triggered more significant metabolic regulations allowing to mitigate the oxidative damage caused by Cd.