One-step synthesis of manganese dioxide/polystyrene nanocomposite foams via high internal phase emulsion and study of their catalytic activity

This paper is devoted to the preparation of manganese dioxide/polystyrene nanocomposite foams via a novel and facile one-step method using high internal phase emulsion as templates. Scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analyses (TGA) techniques were used to characterize the resulting composites. SEM measurements revealed the porous network structure, the average pore diameters ranged from 3.8 to 30.4 μm. The presence of manganese dioxide was identified by XPS pattern, XRD, pattern and FT-IR spectra of the resulting composites. The TGA thermograms showed that the maximum content of manganese dioxide in the nanocomposite foams reached about 15.5%. The applications of the nanocomposite in the oxidative degradation of methylene blue exhibited good catalytic activity in the presence of H₂O₂ as an oxidant.     

One-step synthesis of Pt nanoparticles/reduced graphene oxide composite with enhanced electrochemical catalytic activity

A one-step electrochemical approach for synthesis of Pt nanoparticles/reduced graphene oxide(Pt/RGO) was demonstrated.Graphene oxide(GO) and chloroplatinic acid were reduced to RGO and Pt nanoparticles(Pt NPs) simultaneously,and Pt/RGO composite was deposited on the fluorine doped SnO 2 glass during the electrochemical reduction.The Pt/RGO composite was characterized by field emission-scanning electron microscopy,Raman spectroscopy and X-ray photoelectron spectroscopy,which confirmed the reduction of GO and chloroplatinic acid and the formation of Pt/RGO composite.In comparison with Pt NPs and RGO electrodes obtained by the same method,results of cyclic voltammetry and electrochemical impedance spectroscopy measurements showed that the composite electrode had higher catalytic activity and charge transfer rate.In addition,the composite electrode had proved to have better performance in DSSCs than the Pt NPs electrode,which showed the potential application in energy conversion.     

Synthesis and antibacterial property of hollow SiO2/Ag nanocomposite spheres

This paper presents a novel and facile method to fabricate hollow silica/sliver (SiO(2)/Ag) nanocomposite spheres. In this approach, the monodisperse hollow SiO(2) colloids bearing quantenary ammonium groups were prepared by dispersion polymerization combined sol-gel process and used as templates. The Ag(+) ions were first adsorbed onto the surfaces of the hollow SiO(2) beads via electrostatic interaction and then in situ reduced by the deprotonated silanol groups of the hollow SiO(2) beads, no extra reducing agents or catalysts were added during the reduction process. TEM, SEM and EDX analyses indicated that Ag nanoparticles were successfully deposited onto the surfaces of hollow SiO(2) beads. Some influencing parameters, such as the amount of quantenary ammonium groups in the inner wall of hollow SiO(2) colloids, Ag(+) ions concentration and reaction temperature, on the deposition of Ag nanoparticles onto SiO(2) colloids were investigated. Preliminary antibacterial tests indicated that these hollow nanocomposite spheres showed excellent antibacterial ability.     

Preparation,characterization, catalytic performance and antibacterial activity of Ag photodeposited on monodisperse ZnO submicron spheres

Monodisperse ZnO colloidal spheres were produced by a two-stage sol–gel reaction process. The sub-micrometer sized ZnO/Ag composite spheres were prepared by photodeposition route. The photochemical reduction method needs no other reductant or surfactant and is an effective means to enable the uniform distribution of Ag nanoparticles (NPs) over the ZnO spheres. The size and shape as well as the optical properties of the composites were characterized with transmission electron microscopy and UV–Vis spectroscopy. The results showed that average size of ZnO and Ag NPs among the composites was around 480, 10 nm, respectively. Ag NPs were relatively monodisperse, presented spherical shape, and their deposition over the ZnO surface was uniform. Formation of Ag NPs on the surface of ZnO spheres was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy, and the catalytic performance and antibacterial activity was also investigated. The ZnO/Ag composites possess excellent catalytic performance for catalytic reduction of 4-nitrophenol to 4-aminophenol and can effectively inhibit Escherichia coli and Bacillus subtilis growth at 0.25 mg/mL.     

Synthesis,characterization and antibacterial properties of a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag

In this study, a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag (PANI/PVA/Ag) has been successfully synthesized. The chemical reduction method was used to produce Ag nanoparticle colloidal solution from Ag⁺ ions. The polymerization of aniline occurred in situ for the preparation of polyaniline (PANI) in the presence of ammonium persulfate. With exposure to Ag nanoparticles on the PANI/PVA composite, a new nanocomposite was obtained. The morphology and particle size of the novel nanocomposite was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) analyses. According to XRD analysis, the size of nanoparticles was found to be in the range of 10–17 nm. SEM images showed the favored shape of nanoparticles as triangle which is a benign shape for antibacterial analysis. The antibacterial activity of the obtained nanocomposite was also evaluated against Gram positive bacteria Staphylococcus aureus (Staph. aureus) and Gram negative Escherichia coli (E. coli) using the paper disk diffusion method. The antibacterial study showed that the PANI/PVA composite did not have a very good antibacterial activity but PANI/PVA/Ag nanocomposites were found to be effective against two bacteria.     

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.     

One-step synthesis of Ag6Si2O7/AgCl heterojunction composite with extraordinary visible-light photocatalytic activity and stability

Research on Chemical Intermediates - In this paper, a Z-scheme Ag6Si2O7/AgCl heterojunction composite was successfully constructed via a one-step co-precipitation method and investigated as a novel...     

Waste-grass-mediated green synthesis of silver nanoparticles and evaluation of their anticancer,antifungal and antibacterial activity

Grass waste was used for transform an inexpensive waste into health. Silver nanoparticles (AgNPs) have been synthesized using waste material (dried grass). The average size of silver nanoparticles observed in transmission electron images was estimated to be about 15?nm. The anticancer, antifungal and antibacterial effect of AgNPs were studied in vitro. The minimum inhibitory concentration of AgNPs against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated about 3?µg/ml. The highest level of inhibitory effect of AgNPs against Fusarium solani was close to 90% at a concentration of 20?μg/ml of AgNPs. An inhibitory effect on the cancer cell growth is reach, by increasing the concentration of AgNPs to 5?µg/ml; the cancer cells’ survival decreases about 30%. Western results showed that the expression of Cyclin D1 protein of MCF-7 cell line decreased after treatment with the effective concentration of AgNPs.     

Alga-mediated facile green synthesis of silver nanoparticles: Photophysical,catalytic and antibacterial activity

A facile, convenient and green method has been employed for the synthesis of silver nanoparticles (AgNPs) using dried biomass of a green alga, Chlorella ellipsoidea. The phytochemicals from the alga, as a mild and non-toxic source, are believed to serve as both reducing and stabilizing agents. The formation of silver nanoparticles was confirmed from the appearance of a surface plasmon resonance band at 436 nm and energy dispersive X-ray spectroscopy. The transmission electron microscopy images showed the nanoparticles to be nearly spherical in shape with different sizes. A dynamic light scattering study revealed the average particle size to be 220.8 ± 31.3 nm. Fourier transform infrared spectroscopy revealed the occurrence of alga-derived phytochemicals attached to the outer surface of biogenically accessed silver nanoparticles. The powder X-ray diffraction study revealed the face-centred cubic crystalline structure of the nanoparticles. The as-synthesized biomatrix-loaded AgNPs exhibited a high photocatalytic activity for the degradation of the hazardous pollutant dyes methylene blue and methyl orange. The catalytic efficiency was sustained even after three reduction cycles. A kinetic study indicated the degradation rates to be pseudo-first order with the degradation rate being 4.72 × 10⁻² min⁻¹ for methylene blue and 3.24 × 10⁻² min⁻¹ for methyl orange. The AgNPs also exhibited significant antibacterial activity against four selected pathogenic bacterial strains.     

Cu2O/Ag纳米复合材料的绿色制备与抗菌性能研究

以乙酸铜为铜源、硝酸银为银源并利用天然蜂蜜为还原剂在无模板剂无需高压反应釜的条件下,环保地、简便地制备了Cu_2O/Ag复合材料。并采用X射线衍射、扫描电镜对材料的结构与形貌进行了表征。通过抑菌圈法证明Cu_2O/Ag复合材料相比Cu_2O对大肠杆菌有着更好的抑菌性能,通过分析Cu_2O/Ag对大肠杆菌生长过程的影响发现,当Cu_2O/Ag复合材料的浓度达到10μg/m L时,Cu_2O/Ag复合材料能够彻底抑制大肠杆菌的生长。通过SEM观察了Cu_2O/Ag复合材料对大肠杆菌作用过程中菌种形貌的变化表明,Cu_2O/Ag复合材料对大肠杆菌的抗菌作用过程是先破坏细胞膜结构使细菌断裂成小段,这些小段颗粒逐渐皱缩进而彻底被分解为大分子物质。本文制备的Cu_2O/Ag复合材料在抗菌剂领域具有潜在的应用价值。     

Mandelate and prolinate ionic liquids: synthesis, characterization, catalytic and biological activity

A group of quaternary ammonium mandelates and l-prolinates, as ionic liquids, were synthesized and characterized. The prepared salts were soluble in water and showed high surface activity. The described synthesis of l-prolinate was simple and the obtained ionic liquid contained a chiral anion. l-Prolinate in CH₂Cl₂ was employed for the asymmetric Michael addition of a ketone to nitrostyrene. A yield of 60%, enantioselectivity (upto 50% ee), and good diastereoselectivity (syn/anti ratio of up to 90:10) were obtained for the asymmetric addition of cyclohexanone. These novel ionic liquids proved to be very effective anti-microbial and anti-fungal agents, especially didecyldimethylammonium l-prolinate. Additionally, it was found that phytotoxicity can be a useful tool in assessing the optical forms of ionic liquids.     

On the synthesis and characterization of ZnO/MgO nanocomposite by thermal evaporation technique

ZnO/MgO nanocomposites have been synthesized by an easy and cost effective thermal evaporation technique. Various growth temperatures ranging from 800 to 900 °C were tried. It is observed that the process temperature plays a key role in the formation of ZnO/MgO nanocomposite and the proper formation of ZnO/MgO nanocomposite occurs at 875 °C temperature as confirmed by X-ray diffraction studies. Scanning electron microscopic images indicate that the ZnO/MgO nanocomposite is formed as agglomerated nanoparticles distributed over a large area. Energy dispersive X-ray analyses also reveal that the Mg composition in the synthesized nanocomposite strongly depends on the process temperature. Photoluminescence (PL) spectrum exhibits a blue shift for the ZnO/MgO nanocomposite synthesized at 875 °C indicating the incorporation of Mg into the ZnO crystal lattice. A higher PL intensity ratio of band-edge to deep band emission has been observed for this sample indicating the presence of low crystalline defects.     

Novel zinc(II)/chitosan-based composite: ultrasound-assisted synthesis,catalytic and antibacterial activity

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Green synthesis of Copper oxide nanoparticles decorated with graphene oxide for anticancer activity and catalytic applications

Nanotechnology is an embryonic field that grips countless impacts on the drug delivery system. Nanoparticles as haulers increase the capability of target-specific drug delivery to many folds hence are used in the treatment of dreadful diseases such as cancer, diabetes, etc. This boom has aimed at, to synthesize Copper oxide nanoparticles (CuO-NPs) using Acalypha Indica leaf extract and then incorporated with graphene oxide (GO) to form GO-CuO nanocomposites. Secondly, to sightsee the photocatalytic activity of CuO-NPs and GO-CuO nanocomposites towards the decolorization of methylene blue-dye and to test its activity against HCT-116 Human colon cancer cell lines. Synthesized nanocomposites were characterized using FTIR, UV–vis, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), X-ray Photoelectron Spectroscopy (XPS) and transmission electron microscopy (TEM) analysis. The photocatalytic studies revealed that synthesized nanocomposites have the efficiency to degrade methylene blue dye by 83.20% and cytotoxic activity was found to be 70% against HCT-116 Human colon cancer cell lines at 100 μg/ml. GO-CuO nanocomposites have appreciable activity towards cancer cell lines and photocatalytic activity when compared to nanoparticles as such.     

Microwave-assisted green synthesis of Cyanthillium cinereum mediated gold nanoparticles: Evaluation of its antibacterial,anticancer and catalytic degradation efficacy

Research on Chemical Intermediates - An eco-friendly and one-step microwave-assisted green synthesis of gold nanoparticles (AuNP) was developed using the aqueous leaf broth of Cyanthillium cinereum...     

Photocatalytic,antibacterial and anticancer activity of silver-doped zinc oxide nanoparticles

Silver-doped zinc oxide nanoparticles (Ag-ZnO NPs) were successfully synthesized by the Sol-gel method coated with polyethylene glycol as a stabilizing and capping agent. The UV–Vis spectrophotometer analysis was done to analyze the optical property of the nanoparticles. XRD pattern showed the hexagonal structure of ZnO nanoparticles and the reduction in the intensity of the peaks of Ag-ZnO NPs indicates the incorporation of Ag⁺ ions in the ZnO lattices. The surface structural properties of the NPs were confirmed by Field Emission Scanning Electron Microscope (FE-SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED). The elemental composition of nanoparticles was confirmed by EDAX and XRF-Spectroscopy. The functional group of ZnO and Ag nanoparticles were determined by FT-IR spectroscopy. The photocatalytic activity of Ag-ZnO NPs was studied against ponceau and the maximum degradation percentage was observed to be 89% at 140 min. Further, Ag-ZnO NPs unveiled high potent antibacterial activity against the selected bacterial pathogens and it also rendered significant anticancer activity in UVB-induced HaCaT cells. Consequently, the fluorescent microscopic analysis confirmed the increasing Reactive Oxygen Species (ROS) generation and Mitochondrial Membrane Potential (MMP) loss in the HaCaT cells that leads to the apoptosis induction. Hence, the selected combination of nanoparticles has proven to exhibit higher photocatalytic, antibacterial and anticancer activity. In the near future, it could be an efficient tool for eradicating the dye pollution from wastewater and also preferably be utilized in the cosmetics and pharmaceutical industries to prevent skin cancer.     

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.     

Cryochemical synthesis and antibacterial activity of a hybrid composition based on Ag nanoparticles and dioxidine

Hybrid nanocomposites based on an dioxidine antimicrobial substance modified with silver were produced by means of cryochemical synthesis. TEM, UV-absorption spectroscopy, X-ray diffraction, and surface analysis based on low-temperature argon adsorption showed the formation of hybrid nanosystems consisting of drug substance particles with a size of 50–300 nm including internal small Ag nanoparticles with a size of 2–40 nm. The obtained hybrid nanosystems showed higher antibacterial activity against E. coli 52, S. aureus 144, and M. cyaneum 98 than did the original dioxidine.     

One-step hydrothermal synthesis of hierarchical Ag/Bi2WO6 composites: In situ growth monitoring and photocatalytic activity studies

Hierarchical Ag/Bi₂WO₆ nanomaterials were prepared by a facile one-step hydrothermal method in mixed acetic acid and ethylene glycol (EG) medium. EG is employed as mild reducing agent for the formation of metallic Ag from Ag⁺ precursors. In situ energy dispersive X-ray diffraction (EDXRD) monitoring showed that the hydrothermal formation kinetics of Bi₂WO₆ in the presence of EG was significantly slowed down due to its very high viscosity. The photocatalytic activities of Ag/Bi₂WO₆ composites were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation. The photocatalytic activity of Bi₂WO₆ is strongly influenced by the Ag loading. The enhanced catalytic activity of the composites is based on the cooperative effects of plasmon absorption band and separation of photogenerated electron-hole pairs.