• RAJESHWARI SIVARAJ

      Articles written in Bulletin of Materials Science

    • Biogenic ZnO nanoparticles synthesized using L. aculeata leaf extract and their antifungal activity against plant fungal pathogens

      S Narendhran Rajeshwari Sivaraj

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      In this study, Zinc oxide (ZnO) nanoparticles were synthesized using aqueous extract of Lantana aculeata Linn. leaf and assessed their effects on antifungal activity against the plant fungal pathogens. Synthesized nanoparticles were confirmed by ultraviolet–visible spectroscopy, Fourier transform infrared spectrometer, energy-dispersive X-ray spectrometer, X-ray diffractometer, Field-emission scanning electron microscopy, high-resolution transmission electron microscopy. The antifungal activity of ZnO nanoparticles were determined using the well diffusion method. All the characterization analyses revealed that nanoparticles were highly stable and crystalline in nature. L. aculeata-mediated ZnO nanoparticles were spherical in shape with an average particle size of 12 ± 3 nm. Antifungal studies concluded that the maximum zone of inhibition was observed in Aspergillus flavus (21 ± 1.0 mm) and Fusarium oxysporum (19 ± 1.0 mm) at 100 𝜇g ml-1 concentration. These results clearly indicated the benefits of using ZnO nanoparticles synthesized using biological methods and shown to have antifungal activities and also that it can be effectively used as antifungal agent in environmental aspect of agricultural development.

    • Potentiating effect of ecofriendly synthesis of copper oxide nanoparticles using brown alga: antimicrobial and anticancer activities

      SRI VISHNU PRIYA RAMASWAMY S NARENDHRAN RAJESHWARI SIVARAJ

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      This study reports the in vitro antimicrobial and anticancer activities of biologically synthesized copper nanoparticles. The antimicrobial activity of green synthesized copper oxide nanoparticles was assessed by well diffusion method. The anticancer activity of brown algae-mediated copper oxide nanoparticles was determined by MTT assay against the cell line (MCF-7). Maximum activity was observed with Pseudomonas aeruginosa and Aspergillus niger. Effective growth inhibition of cells was observed to be more than 93% in antibacterial activity. Thus, the results of the present study indicates that biologically synthesized copper nanoparticles can be used for several diseases, however, it necessitates clinical studies to ascertain their potential as antimicrobial and anticancer agents.

    • Toxicity of ZnO nanoparticles on germinating Sesamum indicum (Co-1) and their antibacterial activity

      S NARENDHRAN P RAJIV RAJESHWARI SIVARAJ

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      A comparative study of chemically (ZnO) and biologically synthesized (nano-ZnO) nanoparticles were carried out to determine the effect on seed germination of $Sesamum indicum$ (Co-1) by soaking method. Nano-ZnO is synthesized using $Lantana aculeata$ aqueous extract. Chemical synthesis of ZnO nanoparticles by precipitate method and was characterized by ultraviolet–Visible spectroscopy (UV–Vis), Fourier transform infrared spectrometer(FT-IR), energy dispersive X-ray spectrometer (EDX), X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Antibacterial activity against pathogens was determined using well diffusion method. All the characterization analysis revealed that ZnO and nano-ZnO nanoparticles were spherical in shape with an average particle size of $18 \pm 2$ and $12\pm 3$ nm, respectively.Antibacterial studies conclude that nano-ZnO NPs have maximum zone of inhibition which was observed in $Pseudomonas aeruginosa$ ($15.60 \pm 1.0$ mm) at 100 $\mu$g ml$^{−1}$ concentration when compared to other ZnO NPs. Phytomediate ZnO have no adverse effects on seed germination, root elongation on $S. indicum$. But chemically synthesized ZnO nanoparticles significantly decreased in germination of $S. indicum$-treated samples and no changes were observed in bulk ZnO. These results clearly indicate the benefits of using bio-fabricate ZnO nanoparticles, i.e., more efficient in germination of $S. indicum$ and can also act as antibacterial agent. It can be used as nanofertilizer in environmental aspect of agricultural development.

    • Synthesis and characterization of Eichhornia-mediated copper oxide nanoparticles and assessing their antifungal activity against plant pathogens

      P VANATHI P RAJIV RAJESHWARI SIVARAJ

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      In this paper, we report the biosynthesis and characterization of copper oxide nanoparticles from an aquatic noxious weed, Eichhornia crassipes by green chemistry approach. The aim of this work is to synthesize copper oxide nanoparticles by simple, cost-effective and ecofriendly method as an alternative to other available techniques. The synthesized copper oxide nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) analyses. The synthesized particles were highly stable, spherical in shape with an average diameter of $28\pm 4$ nm. The synthesized nanoparticles were then explored to antifungal activity against plant pathogens. Highest zone of inhibition were observed in 100 $\mu$g ml$^{−1}$ of Eichhornia-mediated copper oxide nanoparticle against Fusarium culmorum and Aspergillus niger. This Eichhornia-mediated copper oxide nanoparticles wereproved to be good antifungal agents against plant fungal pathogens.

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