Green synthesis of RGO-ZnO mediated Ocimum basilicum leaves extract nanocomposite for antioxidant,antibacterial, antidiabetic and photocatalytic activity

Green chemistry of nanomaterials from synthesis to diverse biomedical applications is a discussion of town in the current scientific scenario. In this work, Ocimum basilicum leaves extract was utilized as the reducing agent in the synthesis of ZnO nanoparticles. Green synthesized ZnO NPs mediated via Ocimum basilicum extract were decorated on the reduced graphene oxide (RGO) sheet by the simple one-step method. The prepared green synthesized RGO-ZnO nanocomposites (NCs) were characterized via the X-ray diffractometer. The average crystallite size of ZnO was 25 nm which confirmed the wurtzite hexagonal structure of ZnO. The scanning Electron Microscopy technique confirmed the spherical morphology of particle size of 31 nm. Further, Fourier Transform Infrared Spectroscopy confirms the Zn-O bond stretching in the RGO-ZnO NCs. Antioxidant activity of the green synthesized Ocimum basilicum ZnO NPs and RGO-ZnO NCs were performed by DPPH scavenging activities and found the dose-dependent. RGO-ZnO effectively inhibited the α-amylase and α-glucosidase for in vitro antidiabetic activities. Moreover, RGO-ZnO NCs showed the antibacterial potential with increasing concentration against the gram-positive (Cocci) and gram-negative (E. coli) bacterial strains. In Photocatalytic activity, the ZnO NPs and RGO-ZnO NCs were utilized as the catalyst and degraded the Rh-B dye 91.4% and 96.7% under UV–visible light. Overall, RGO-ZnO NCs showed better results in antibacterial, antidiabetic activity as well as photocatalytic activity against the pure ZnO NPs. Hence, RGO-ZnO nanocomposites have demonstrated the opportunity to be an entrancing material for photocatalysis and biological studies.     

Effect of Mg doping on morphology,photocatalytic activity and related biological properties of Zn1−xMgxO nanoparticles

The objective of this study is to synthesize ZnO and Mg doped ZnO (Zn_1−xMg_xO) nanoparticles via the sol-gel method, and characterize their structures and to investigate their biological properties such as antibacterial activity and hemolytic potential.Nanoparticles (NPs) were synthesized by the sol-gel method using zinc acetate dihydrate (Zn(CH₃COO)₂.2H₂O) and magnesium acetate tetrahydrate (Mg(CH₃COO)₂.4H₂O) as precursors. Methanol and monoethanolamine were used as solvent and sol stabilizer, respectively. Structural and morphological characterizations of Zn_1−xMg_xO nanoparticles were studied by using XRD and SEM-EDX, respectively. Photocatalytic activities of ZnO and selected Mg-doped ZnO (Zn_1−xMg_xO) nanoparticles were investigated by degradation of methylene blue (MeB). Results indicated that Mg doping (both 10% and 30%) to the ZnO nanoparticles enhanced the photocatalytic activity and a little amount of Zn0.90 Mg0.10 O photocatalyst (1.0 mg/mL) degraded MeB with 99% efficiency after 24 h of irradiation under ambient visible light. Antibacterial activity of nanoparticles versus Escherichia coli ( E. coli ) was determined by the standard plate count method. Hemolytic activities of the NPs were studied by hemolysis tests using human erythrocytes. XRD data proved that the average particle size of nanoparticles was around 30 nm. Moreover, the XRD results indicatedthat the patterns of Mg doped ZnO nanoparticles related to ZnO hexagonal wurtzite structure had no secondary phase for x ≤ 0.2 concentration. For 0 ≤ x ≤ 0.02, NPs showed a concentration dependent antibacterial activity against E. coli . While Zn_0.90Mg_0.10 O totally inhibited the growth of E. coli , upper and lower dopant concentrations did not show antibacterial activity.     

Preparation and characterization of poly(amide-imide)/ZnO nanocomposites containing pendent benzoxazole and benzimidazole segments

In the present investigation, novel poly(amid-imide)/zinc oxide nanocomposites (PAI/ZnO NCs) containing benzoxazole and benzimidazole pendent groups with different amounts of modified zinc oxide nanoparticles (ZnO NPs) were successfully prepared via the ex situ method. Poly(amid-imide) (PAI) was prepared by direct polycondensation of 2-[3,5- bis(N-trimellitimidoyl)phenyl]benzoxazole (DCA) with 5-(2-benzimidazole)-1,3-phenylenediamine (DAMI) and provided the polymeric matrix with well-designed groups. The surface of ZnO NPs was functionalized with 3-aminopropyltriethoxysilane (APS) coupling agent to have a better dispersion and enhancing possible interactions of NPs with functional groups of polymer matrix. The amount of APS bonded to the ZnO surface was determined by thermogravimetric analysis. PAI/ZnO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). SEM analysis showed that the modified ZnO nanoparticles were homogeneously dispersed in polymer matrix. In addition, TGA data indicated an enhancement of thermal stability of the nanocomposite compared with the neat polymer.     

Photocatalytic Oxidative Coupling of Methane over Au1Ag Single-Atom Alloy Modified ZnO with Oxygen and Water Vapor: Synergy of Gold and Silver

C−H dissociation and C−C coupling are two key steps in converting CH₄ into multi-carbon compounds. Here we report a synergy of Au and Ag to greatly promote C₂H₆ formation over Au₁Ag single-atom alloy nanoparticles (Au₁Ag NPs)-modified ZnO catalyst via photocatalytic oxidative coupling of methane (POCM) with O₂ and H₂O. Atomically dispersed Au in Au₁Ag NPs effectively promotes the dissociation of O₂ and H₂O into *OOH, promoting C−H activation of CH₄ on the photogenerated O⁻ to form *CH₃. Electron-deficient Au single atoms, as hopping ladders, also facilitate the migration of electron donor *CH₃ from ZnO to Au₁Ag NPs. Finally, *CH₃ coupling can readily occur on Ag atoms of Au₁Ag NPs. An excellent C₂H₆ yield of 14.0 mmol g⁻¹ h⁻¹ with a selectivity of 79 % and an apparent quantum yield of 14.6 % at 350 nm is obtained via POCM with O₂ and H₂O, which is at least two times that of the photocatalytic system. The bimetallic synergistic strategy offers guidance for future catalyst design for POCM with O₂ and H₂O.     

Toxicological effect of ZnO nanoparticles based on bacteria

Streptococcus agalactiae and Staphylococcus aureus are two pathogenetic agents of several infective diseases in humans. Biocidal effects and cellular internalization of ZnO nanoparticles (NPs) on two bacteria are reported, and ZnO NPs have a good bacteriostasis effect. ZnO NPs were synthesized in the EG aqueous system through the hydrolysis of ionic Zn2+ salts. Particle size and shape were controlled by the addition of the various surfactants. Bactericidal tests were performed in an ordinary broth medium on solid agar plates and in liquid systems with different concentrations of ZnO NPs. The biocidal action of ZnO materials was studied by transmission electron microscopy of bacteria ultrathin sections. The results confirmed that bactericidal cells were damaged after ZnO NPs contacted with them, showing both gram-negative membrane and gram-positive membrane disorganization. The surface modification of ZnO NPs causes an increase in membrane permeability and the cellular internalization of these NPs whereas there is a ZnO NP structure change inside the cells.     

Single-stage in situ synthesis of silver nanoparticles in antibacterial self-assembled overlays

In this work, a novel single-stage process for in situ synthesis of Ag nanoparticles (NPs) using the layer-by-layer (LbL) technique is presented. The Ag NPs were formed into nanotextured coatings based on sequentially adsorbed poly(allylamine hydrochloride) (PAH) and SiO₂ NPs. Such highly porous surfaces have been used in the fabrication of highly efficient ion release films for applications such as antibacterial coatings. In this approach, the amino groups of the PAH acted as reducing agent and made possible the in situ formation of the Ag NPs. This reduction reaction occurred during the LbL process as the coating was assembled, without any further step after the fabrication and stabilization of the multilayer film. Biamminesilver nitrate was used as the Ag⁺ ion source during the LbL process and it was successfully reduced to Ag NPs. All coatings were tested with gram-positive and gram-negative bacterial cultures of Escherichia coli, Staphylococcus aureus, and Lactobacillus delbrueckii showing an excellent antimicrobial behavior against these types of bacteria (more than 99.9% of killing efficiency in all cases).     

Characterization of bis-Schiff bases synthesized using ZnFe2O4 nanoparticles as catalyst,and examination of their antibacterial and in vitro cytotoxic properties

In this study, ZnFe₂O₄ nanoparticles (NPs) were prepared by a hydro/solvothermal method, and their structures were characterized by infrared, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analyses. These ZnFe₂O₄ NPs were used in the synthesis of new bis-Schiff bases by condensation of hydroxyl-substituted aldehydes with various aromatic diamines in aqueous media. The antimicrobial activities of the synthesized bis-Schiff bases were tested against gram-negative as well as gram-positive bacteria. The MTT method was used to assess the anticancer activity of the bis-Schiff bases towards human lung and breast cancer cell lines. The results indicated that these compounds could be considered as new anti-tumor candidates.     

Fabrication and magnetic properties of FePt nanoparticle assemblies embedded in MgO-matrix systems

Hydrophilic FePt nanoparticles (NPs) have been embedded into the MgO-matrix systems via a sol–gel process to prevent FePt NPs from aggregating and sintering during the heat-treatment process required for the L1₀ ordering. The chemically ordered L1₀-phase FePt can be obtained after annealing at 700 °C for 60 min in atmosphere containing H₂. The effect of the pH value of MgO collosol and FePt nanocrystal loading amount on the structure, morphology, and magnetic properties of FePt/MgO nanocomposites has been investigated. The neutral pH value of 7 in MgO sol is beneficial to stabilize FePt NPs and obtain higher chemical ordering parameter S for the face-centered tetragonal -FePt/MgO nanocomposites with larger coercivity. The FePt NPs loading amount also plays a key role in tuning the microstructure and magnetic properties of the nanocomposites. The relatively higher FePt NPs loading with FePt/MgO molar ratio (R_FM) of 1:2 leads to relatively perfect hexagonal assembly and pure L1₀ phase. When the R_FM is 1:5 and 1:10, the MgO-matrix in nanocomposites causes the Fe element loss in FePt NPs along with formation of secondary phases such as magnesioferrite or Pt₃Fe during the annealing process. Under optimal processing of neutral pH value of 7 and R_FM of 1:2, the presence of MgO matrix produces more homogeneous microstructures and better magnetic properties with higher room-temperature coercivity (H _C = 4.65 kOe).     

The surface modification of spherical ZnO with Ag nanoparticles: A novel agent,biogenic synthesis,catalytic and antibacterial activities

Nowadays, the industrial wastewater pollutants including toxic dyes and pathogenic microbes have caused serious environmental contaminations and human health problems. In the present study, eco-friendly and facile green synthesis of Ag modified ZnO nanoparticles (ZnO-Ag NPs) using Crataegus monogyna (C. monogyna) extract (ZnO-Ag@CME NPs) is reported. The morphology and structure of the as-biosynthesized product were characterized by field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), differential reflectance spectroscopy (DRS), dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS) techniques. TEM and FESEM images confirmed the oval and spherical-like structure of the products with a size of 55–70 nm. The EDS analysis confirmed the presence of Zn, Ag, and O elements in the biosynthesized product. The photocatalytic results showed ZnO-Ag@CME NPs were degraded (89.8% and 75.3%) and (94.2% and 84.7%) of methyl orange (MO) and basic violet 10 (BV10), under UV and sunlight irradiations, respectively. The Ag modified ZnO nanoparticles exhibited enhanced catalytic activity towards organic pollutants, and showed better performance than the pure ZnO nanoparticles under UV and sunlight irradiations. This performance was probably due to the presence of silver nanoparticles as a plasmonic material. Antibacterial activity was performed against different bacteria. ZnO-Ag@CME NPs showed high antibacterial activity against K. pneumoniae, S. typhimurium, P. vulgaris, S. mitis, and S. faecalis with MIC values of 50, 12.5, 12.5, 12.5, and 12.45 µg/mL, respectively. All in all, the present investigation suggests a promising method to achieve high-efficiency antibacterial and catalytic performance.     

Evaluation of the toxicity of ZnO nanoparticles to Chlorella vulgaris by use of the chiral perturbation approach

The toxicity of ZnO nanoparticles (NPs) has been widely investigated because of their extensive use in consumer products. The mechanism of the toxicity of ZnO NPs to algae is unclear, however, and it is difficult to differentiate between particle-induced toxicity and the effect of dissolved Zn²⁺. In the work discussed in this paper we investigated particle-induced toxicity and the effects of dissolved Zn²⁺ by using the chiral perturbation approach with dichlorprop (DCPP) as chiral perturbation factor. The results indicated that intracellular zinc is important in the toxicity of ZnO NPs, and that ZnO NPs cause oxidative damage. According to dose–response curves for DCPP and the combination of ZnO NPs with (R)-DCPP or (S)-DCPP, the toxicity of DCPP was too low to perturb the toxicity of ZnO NPs, so DCPP was suitable for use as chiral perturbation factor. The different glutathione (GSH) content of algal cells exposed to (R)-DCPP or (S)-DCPP correlated well with different production of reactive oxygen species (ROS) after exposure to the two enantiomers. Treatment of algae with ZnO NPs and (R)-DCPP resulted in reduced levels of GSH and the glutathione/oxidized glutathione (GSH/GSSG) ratio in the cells compared with the control. Treatment of algae with ZnO NPs and (S)-DCPP, however, resulted in no significant changes in GSH and GSH/GSSG. Moreover, trends of variation of GSH and GSH/GSSG were different when algae were treated with ZnSO₄·7H₂O and the two enantiomers. Overall, the chiral perturbation approach revealed that NPs aggravated generation of ROS and that released Zn²⁺ and NPs both contribute to the toxicity of ZnO NPs.

ZnO nanopowders and their excellent solar light/UV photocatalytic activity on degradation of dye in wastewater

Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m~2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.     

Cellular compatibility of biomineralized ZnO nanoparticles based on prokaryotic and eukaryotic systems

Zinc oxide nanoparticles (NPs) with the size of ～100 nm were prepared via a facile biomineralization process in the template of silk fibroin (SF) peptide at room temperature. These ZnO NPs have shown the remarkable behavior of low toxicity to gram-positive bacteria (Staphylococcus aureus, Staphylococcus agalactiae), gram-negative bacteria (Escherichia coli), and eukaryotic cells (mouse L929 fibroblasts). Bacteriological testing indicated that ZnO NPs presented a 50% inhibitory effect on Streptococcus agalactiae at the concentrations of >100 mM, whereas at the same concentrations, the growth of Staphylococcus aureus and Escherichia coli were hardly inhibited. On the other hand, a remarkable proliferation of Staphylococcus aureus or Escherichia coli was observed at the concentrations of ZnO NPs <50 mM. Moreover, the cytotoxicity test demonstrated that ZnO NPs mineralized with SF peptide possessed a low toxicity to mouse L929 fibroblasts. The SF peptide coated on the surface of ZnO NPs permitted greater adhesion and consequently greater proliferation of mouse L929 fibroblasts. Besides, from TEM micrographs of the cell ultrastructure, endocytosis of NPs into the cytoplasm can be detected and the ultrastructure of the cell underwent few changes. The cell membrane retained integrity, euchromatin dispersed homogenously inside the cytoplasm, the mitochondrial architecture remained intact, and no intracellular vacuoles were observed. High-resolution transmission electron microscopy images and selected area electron diffraction patterns of ultrathin cell sections indicated that the crystal structure of NPs was not damaged by the organelle or cytoplasm. All these observations indicated that ZnO NPs mineralized with the SF peptide possess good cytocompatibility.     

Biosynthesized Zinc Oxide Nanoparticles as Efficient Photocatalytic and Antimicrobial Agent

This work reports an innovative, effortless and inexpensive method for the preparation of ZnO nanoparticles by green approach using leaf extract of Piper betleas a reducing-stabilizing negotiator. The prepared ZnO NPs were characterized through XRD, FTIR, UV–Visible spectroscopy, and EDX etc. The band gap energy of the sample was estimated as 3.41 eV which is larger than the bulk ZnO (E_g?=?3.37 eV). The observed blue shift is attributed to the quantum confinement of excitons. FTIR analysis showed the presence of alkaloids, flavonoids, polyphenols, and terpenoid. TEM analysis showed that each nanoparticle comprised of 1 to 2 nano-crystallites. Photocatalytic activity results revealed that ZnO-NPs prepared through green synthesis route were found to be efficient in the degradation of toxic reactive red dye with degradation efficiency of 96.4% having high photodegradation rate-constant of 1.6?×?10^–2 min^?1. As an antimicrobial agent, the ZnO NPs are effective against both gram-positive (Bacillus subtilis) and negative bacteria (Escherichia coli), with the zones of clearance as 16.4 and 14.3 mm, respectively. Therefore, present research signifies an effective approach to utilize as-prepared ZnO NPs as efficient photocatalysts as well as antimicrobial agent.

     

Ternary Ag/Polyaniline/Au nanocomposites: Preparation,characterization and electrochemical properties

Ternary Ag/Polyaniline/Au nanocomposites were synthesized successfully by immobilizing of Au nanoparticles (NPs) on the surface of Ag/Polyaniline (PANI) nanocomposites. Ag/PANI nanocomposites were prepared via in situ chemical polymerization of aniline in the presence of 4-aminothiophenol (4-ATP) capped silver colloidal NPs. Then, uniform gold (Au) NPs were assembled on the surface of resulted Ag/PANI nanocomposites through electrostatic interaction to get Ag/Polyaniline/Au nanocomposites. The nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), ultraviolet visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Moreover, Ag/PANI/Au nanocomposites were immobilized on the surface of a glassy carbon electrode and showed enhanced electrocatalytic activity for the reduction of H₂O₂ compared with Ag/PANI.     

Antimicrobial,mechanical, optical and thermal properties of PVC/ZnO‐EDTA nanocomposite films

Covalent surface functionalization of synthesized ZnO nanoparticles (NP)s with ethylenediaminetetraacetic acid (EDTA) was successfully carried out. Modified ZnO‐EDTA NPs as a viable and inexpensive filler were incorporated into poly(vinyl chloride) PVC matrix after their chemical modification to investigate the agglomeration behavior. All prepared materials including modified NPs and PVC/ZnO‐EDTA nanocomposites (NC)s were analyzed by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, X‐ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Fabricated PVC/ZnO‐EDTA NCs were reported to have high transparency and improved mechanical properties compared with PVC. Modified ZnO and the fabricated NCs were shown to exhibit excellent antibacterial activity against two bacteria species: Escherichia coli and Staphylococcus aureus. The obtained NCs could be considered as self‐extinguishing materials on the basis of the LOI values. Copyright © 2016 John Wiley & Sons, Ltd.     

MnO<Subscript>2</Subscript> Nanoparticles and Carbon Nanofibers Nanocomposites with High Sensing Performance Toward Glucose

By combining the advantages of manganese dioxide nanoparticles (MnO₂ NPs) and carbon nanofibers (CNFs), a biosensing electrode surface as a high-performance enzyme biosensor is designed in this work. MnO₂ NPs and CNFs nanocomposites (MnO₂–CNFs) were prepared by using a simple hydrothermal method and then were characterized by scanning electron microscopy, powder X-ray diffraction, fourier transform infrared spectroscopy, energy dispersive spectrometry and electrochemisty. The results showed that MnO₂ NPs are uniformly attached to the surface of CNFs. Meanwhile, the MnO₂–CNFs nanocomposites as a supporting matrix can provide an efficient and advantageous platform for electrochemical sensing applications. On the basis of the improved sensitivity of MnO₂–CNFs modified electrode toward H₂O₂ at low overpotential, a MnO₂–CNFs based glucose biosensor was fabricated by monitoring H₂O₂ produced by an enzymatic reaction between glucose oxidase and glucose. The constructed biosensor exhibited a linear calibration graph for glucose in a concentration range of 0.08–4.6 mM and a low detection limit of 0.015 mM. In addition, the biosensor showed other excellent characteristics, such as high sensitivity and selectivity, short response time, and the relative low apparent Michaelis–Menten constant. Analysis of human urine spiked with glucose at different concentration levels yielded recoveries between 101.0 and 104.8%.     

Preparation and characterization of novel PES‐(SiO2‐g‐PMAA) membranes with antifouling and hydrophilic properties for separation of oil‐in‐water emulsions

In the present study, modification of nanoparticles (NPs) was investigated to mitigate aggregation of SiO₂ nanoparticles and improve the polymeric membrane's performance. For this purpose, the surface of SiO₂ nanoparticles was activated with amine groups, and polymethacrylic acid (PMAA) was grafted on the surface of NPs by atom transfer radical polymerization. Modified NPs were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) tests. Polyethersulfone (PES) membranes were fabricated with both SiO₂ and SiO₂‐g‐PMAA NPs via nonsolvent‐induced phase separation method. The fabricated membranes were characterized regarding their permeability, hydrophilicity, and porosity properties, and their separation efficiency was tested using the synthetic oil‐in‐water emulsion. The surface and cross‐sectional morphologies of membranes were observed by field emission scanning electron microscopy (FESEM). The experimental trials showed that modified NPs dispersed more uniformly in the structure of membranes and hydroxyl groups on the surface of NPs acted more effectively. Modification of NPs enhance the membrane performance in terms of permeate flux, hydrophilicity, and porosity. NPs modification improved the permeate flux about 46%. Oil rejection for all tested membranes was more than 98%, and modification of NPs did not reduce the rejection of membranes. The optimum concentration was obtained as 1 wt.% and 1.5 wt.% for SiO₂ and SiO₂‐g‐PMAA, respectively. Aggregation effect dominated at concentrations beyond the optimum values that decreased the permeate flux, consequently.     

Probing nanocolumnar silver nanoparticle/zinc oxide hierarchical assemblies with advanced surface plasmon resonance and their enhanced photocatalytic performance for formaldehyde removal

Recent advances in photocatalysis focus on the development of materials with hierarchical structure and on the surface plasmon resonance (SPR) phenomenon exhibited by metal nanoparticles (NPs). In this work, both are combined in a material where size‐controllable Ag‐NPs are uniformly loaded onto the hierarchical microporous and mesoporous and nanocolumnar structures of ZnO, resulting in Ag‐NP/ZnO nanocomposites. The embedded Ag‐NPs slightly decrease the hydrophobicity of fibrous ZnO, improve its wettability, and increase the absorption of formaldehyde (H₂CO) onto the photocatalyst, all of this resulting in excellent photodegradation of formaldehyde in aqueous solution. Besides, we found that Ag‐NPs with optimal size not only accelerate the charge transfer to the surface of ZnO, but also strengthen the SPR effect in the intercolumnar channels of fibrous ZnO particles combining with high concentration of photo‐generated radical species. The micro‐to‐mesoporous ZnO is like a nanoarray packed Ag‐NPs. With Ag‐NPs of diameter 2.5 < ? < 6.5 nm, ZnO exhibits the most superior photodegradation rate constant value of 0.0239 min^?1 with total formaldehyde removal of 97%. This work presents a new feasible approach involving highly sophisticated Ag‐NP/ZnO architecture combining the SPR effect and hierarchically ordered structures, which results in high photocatalytic activity for formaldehyde photodegradation.     

Antibacterial polyethylene - Ethylene vinyl acetate polymeric blend by incorporation of zinc oxide nanoparticles

In this work, a Low-Density Polyethylene (LDPE) - Ethylene Vinyl Acetate (EVA) polymeric blend with antimicrobial activity was obtained. The main objective was to develop an antibacterial LDPE-EVA polymeric blend from the incorporation of antibacterial nanoparticles to increase the antimicrobial and sanitary safety of this polymeric blend when applied in the manufacture of medical products. The antibacterial activity was obtained from the incorporation of zinc oxide nanoparticles (ZnO-NPs) in the LDPE-EVA polymeric blends and the thermal properties were evaluated by differential scanning calorimetry and the mechanical properties by tensile stress tests for different percentages of ZnO-NPs. Scanning electron microscopy was used to study the morphological characteristics of the ZnO-NPs and also the characteristics of the distribution of nanoparticles in the polymer blends. The dispersive energy of x-ray fluorescence spectroscopy was used to study the chemical composition of the nanoparticles. Microbiological tests were performed to evaluate the antibacterial activity of the LDPE-EVA polymeric blends without and with ZnO-NPs against the bacteria Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative). The results obtained were excellent for the future application of the antibacterial LDPE-EVA polymeric blends to the manufacture of medical products. The Young's modulus values decreased and the tensile strength values showed small reductions and the thermal properties of the LDPE-EVA were not modified. However, the antibacterial activity of LDPE-EVA with 4 wt% of ZnO-NPs was excellent, eliminating the gram-positive bacteria in just 2 h and the gram-negative bacteria in just 2.5 h on their surfaces.     

Corallocarpus epigaeus mediated synthesis of ZnO/CuO integrated ZrO2 nanoparticles for enhanced in-vitro antibacterial,antifungal and antidiabetic activities

Zirconia based nanocomposites have attracted much research attention in recent years due to their exceptional biomedicinal activities. Rhizome extracts of Corallocarpus epigaeus based ZrO₂/CuO–ZnO nanocomposite were green synthesized in a facile synthesis strategy. The nanocomposites were examined with XRD technique for their structural information and FT-IR technique for surface functional group analysis. Electron microscopic images aided to elucidate the CuO and ZnO nanoparticles decorated ZrO₂ nanostructures. UV–vis absorption spectroscopic studies of the nanocomposite revealed the characteristic UV absorption of ZrO₂ and enhanced visible region absorption for the incorporated nanoparticles. Antibacterial and antifungal studies indicated enhanced activity of nanocomposites over the pristine zirconia nanoparticles. ZrO₂/CuO–ZnO nanocomposite had exhibited about 75% of α-amylase inhibition activity, whereas pristine ZrO₂ nanoparticles had exhibited only 57% suggesting the worthwhile application in the antidiabetic activity of the nanocomposite.