ZnO nanoparticles prepared via a green synthesis approach: Physical properties, photocatalytic and antibacterial activity

The synthesis of Zinc oxide nanoparticles using a plant-mediated approach is presented in this paper. The nanoparticles were successfully synthesized using the Nitrate derivative of Zinc and plant extract of the indigenous medicinal plant Cayratia pedata. 0.1 mM of Zn (NO3)2.6H2O was made to react with the plant extract at different concentrations, and the reaction temperature was maintained at 55 °C, 65 °C, and 75 °C. The yellow coloured paste obtained was wholly dried, collected, and packed for further analysis. In the UV visible spectrometer (UV–Vis) absorption peak was observed at 320 nm, which is specific for Zinc oxide nanoparticles. The characterization carried out using Field Emission Scanning Electron Microscope (FESEM) reveals the presence of Zinc oxide nanoparticles in its agglomerated form. From the X-ray diffraction (XRD) pattern, the average size of the nanoparticles was estimated to be 52.24 nm. Energy Dispersive Spectrum (EDX) results show the composition of Zinc and Oxygen, giving strong energy signals of 78.32% and 12.78% for Zinc and Oxygen, respectively. Fourier Transform - Infra-Red (FT-IR) spectroscopic analysis shows absorption peak of Zn–O bonding between 400 and 600 cm−1. The various characterization methods carried out confirm the formation of nano Zinc oxide. The synthesized nanoparticles were used in the immobilization of the enzyme Glucose oxidase. Relative activity of 60% was obtained when Glucose oxidase was immobilized with the green synthesized ZnO nanoparticles. A comparative study of the green synthesized with native ZnO was also carried out. This green method of synthesis was found to be cost-effective and eco-friendly.

Green synthesis and characterization of zinc oxide nanoparticles using Cayratia pedata leaf extract.

Bio-acceptable 0D and 1D ZnO nanostructures for cancer diagnostics and treatment

Textile wastewater comprises a complex mixture of chemical substances and dyes such as disperse dyes which have a high potential as carcinogenic, mutagenic, and teratogenic. Textile wastewater effluent contributes 20% of the water pollution with a high contribution to environmental contamination, where about 50,000 tons/year of dyes are dumped into the environment. The advanced oxidation processes (AOPs), which includes photocatalytic degradation (PD) using nanophotocatalysts, is a rising technology causing in completing the mineralization of the dyes, compared to traditional treatment techniques such as the absorption method, which transfers the pollutants to other stages. Photolysis is capable of partially degrading 50 to 80% of micro-pollutants like dyes using nanophotocatalysts. The literature indicates that about 70 to 80% of studies use photocatalysis using ZnO/TiO2 as a photocatalyst in wastewater treatment. However, the photocatalysts used have limited potential for removing dyes from textile wastewater. Thus, it is urgent to improve the ZnO NPs synthesis to maximize the PD efficiency to degrading textile wastewater dyes. The present review focuses on exploring the efficiency and mechanism of the photodegradation of textile wastewater dyes using zinc oxide nanoparticles (ZnO NPs) synthesized in the plant extract. The highest photolysis efficiency was found at low dye concentrations and pH to improve the initial operating parameters. Photolysis increases with increasing photocatalysis in the surface area and with an optimum amount of photocatalyst. Furthermore, appropriate photoirradiation is also necessary to conduct the photocatalytic process at room temperature. 

Photocatalytic degradation of disperse azo dyes in textile wastewater using green zinc oxide nanoparticles synthesized in plant extract: A critical review

Biosynthesis of zinc oxide nanoparticles (ZnO-NPs) was achieved by utilizing the reducing and capping potential of leaf, stem and callus aqueous extracts of Mussaenda frondosa.The bioreduced ZnO-NPs were characterized using powder X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis spectroscopy), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) techniques. UV–visible spectra of ZnO-NPs showed a strong absorption peak at 370, 376 and 373 nm corresponding to the band gap energy of 3.33, 3.27 and 3.30 eV for ZnO-NPs obtained from leaf (L-ZnO-NP), stem (S-ZnO-NP) and callus (C-ZnO-NP) aqueous extracts, respectively. XRD analysis confirmed the formation of hexagonal wurtzite structures having an average grain size between 5 and 20 nm in diameter. FTIR spectra revealed the presence of stretching vibrations of –O–H, C–H, C–N, C = O groups involved in reduction and stabilization of nanoparticles. SEM images recognize the presence of spongy, spherical, porous agglomerated nanoparticles. DLS analysis and zeta potential values validated the stability of ZnO-NPs. The present investigation puts light on the photocatalytic activity and biological (antioxidant, anti-inflammatory, antidiabetic, antimicrobial, anticancerous) applications of ZnO-NPs. The current study is an attempt to describe an effective, simple and eco-friendly method of ZnO-NP synthesis and to evaluate its potential for various industrial and medical applications.

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Green synthesis of zinc oxide nanoparticles from the leaf, stem and in vitro grown callus of Mussaenda frondosa L.: characterization and their applications

Growth-phase specific regulation of cviI/R based quorum sensing associated virulence factors in Chromobacterium violaceum by linalool, a monoterpenoid

Article history: Received on: 27/07/2015 Revised on: 22/08/2015 Accepted on: 17/09/2015 Available online: 27/11/2015 Dietary antioxidants are known to play a key role in combating the cellular oxidative stress imposed by the free radicals as well as in inhibiting the undesirable changes in nutritional quality of food. The present investigation was designed to evaluate the in vitro antioxidant properties and the major phytoconstituents of some plants regularly used in Indian traditional diet. Methanolic extracts of Costus igneus, Foeniculum vulgare, Leucas aspera, Muntingia calabura, Physalis minima and Sauropus androgynus were prepared by maceration. Antioxidant activities were assessed using phosphomolybdenum method and ferric reducing power assays. Total antioxidant activities of methanolic extracts ranged between 4.89 μg/ml to 46.0 μg/ml ascorbic acid equivalents for the tested extracts. F. vulgare methanolic extract possessed maximum antioxidant activity. This investigation revealed the potential antioxidant activity of the tested extracts and therefore, their use in the regular diet will be helpful in combating free radical associated health effects. Also, antioxidant rich formulations can be prepared using these plant materials.

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Rekha Punchappady Devasya

Papers

Green synthesis of zinc oxide nanoparticles from the leaf, stem and in vitro grown callus of Mussaenda frondosa L.: characterization and their applications

Growth-phase specific regulation of cviI/R based quorum sensing associated virulence factors in Chromobacterium violaceum by linalool, a monoterpenoid

Growth-phase specific regulation of cviI/R based quorum sensing associated virulence factors in Chromobacterium violaceum by linalool, a monoterpenoid

Phytochemical constituents and antioxidant activities of some plants commonly used in Indian traditional diet