Influence of Fe-Doping on the Structural, Morphological, Optical, Magnetic and Antibacterial Effect of ZnO Nanostructures.

Pure and Fe-doped ZnO nanostructures with different weight ratios (0.5, 1.0, 1.5, and 2.0 at wt% of Fe) were successfully synthesized by a facile microwave combustion method using urea as a fuel. The detailed structural characterization was performed by means of X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). XRD patterns refined by the Rietveld method indicated that Fe-doped ZnO have a single pure phase with wurtzite structure, suggesting that Fe ions are successfully incorporated into ZnO crystal lattice by occupying Zn ionic sites. Interestingly, the morphology was found to change substantially from grains to nanoflakes and then into nanorods with the variation of Fe-content. The optical band gap estimated using DRS was found to be red-shifted from 3.220 eV for the pure ZnO nanostructures, then decreases up to 3.200 eV with increasing Fe-content. Magnetic studies showed that Fe-doped ZnO nanostructures exhibit room temperature ferromagnetism (RTFM) and the saturation magnetization attained a maximum value of 8.154 x 10(-3) emu/g for the highest Fe-content. The antibacterial activity of pure and Fe-doped ZnO nanostructures against a Gram-positive bacteria and Gram-negative bacteria was investigated. Pure ZnO and Fe-doped ZnO exhibited antibacterial activity, but it was considerably more effective in the 1.5 wt% Fe-doped ZnO nanostructures.

Phyto mediated biogenic synthesis of silver nanoparticles using leaf extract of Andrographis echioides and its bio-efficacy on anticancer and antibacterial activities.

The present study reveals the efficiency of Andrographis echioides for green synthesis of silver nanoparticles (AgNPs). The leaf aqueous extract of A. echioides was used for the synthesis of AgNPs and they were characterized by UV-visible, High Resonance Scanning Electron Microscope (HRSEM), Energy-Dispersive X-ray Spectroscopy (EDX), Atomic Force Microscope (AFM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The toxicity of AgNPs was evaluated by using MTT assay. Our present study showed that biosynthesized AgNPs inhibited proliferation of human breast adenocarcinoma cancer cell line (MCF-7) with 31.5 µg/mL at 24h incubation. Results suggest that AgNPs may exert its anticancer activity on MCF-7 cell line by suppressing its growth. The silver nanoparticles was studied against Gram positive and Gram negative bacteria. The highest antibacterial activity was found against Escherichia coli (28 mm) and Staphylococcus aureus (23 mm) respectively.

Electrochemical, catalytic and antimicrobial activity of N-functionalized tetraazamacrocyclic binuclear nickel(II) complexes.

The five binuclear nickel(II) complexes have been synthesized by the Schiff base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclo-tetradecane (PC) with appropriate aliphatic diamines and nickel(II) perchlorate. All the five complexes were characterized by elemental and spectral analysis. The electronic spectra of the complexes show three d-d transition in the range of 550-1055 nm due to 3A2g→3T2g(F), 3A2g→3T1g(F) and 3A2g→3T1g(P). These spin allowed electronic transitions are characteristic of an octahedral Ni2+ center. Electrochemical studies of the complexes show two irreversible one electron reduction waves at cathodic region. The reduction potential of the complexes shifts towards anodically upon increasing the chain length of the macrocyclic ring. All the nickel(II) complexes show two irreversible one electron oxidation waves at anodic region. The oxidation potential of the complexes shift towards anodically upon increasing the chain length of the macrocyclic ring. The catalytic activities of the complexes were observed to be increase with increase the macrocyclic ring size. The observed rate constant values for the catalytic hydrolysis of 4-nitrophenyl phosphate are in the range of 5.85×10(-3) to 9.14×10(-3) min(-1). All the complexes were screened for antimicrobial activity.