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Thirunavukkarasu Arunachalam, Muthukumaran Karpagasundaram and Nithya Rajarathinam

Abstract

Cerium oxide nanoparticles (CONPs) were prepared using ultrasound assisted leaf extract of Prosopis juliflora acting as a reducing as well as stabilizing agent. The synthesized CONPs were characterized by ultraviolet-visible absorption spectroscopy (UV-Vis), particle size analyzer (PSA), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). From the UV-Vis analysis, the optical band gap of the prepared CONPs (Eg = 3.62 eV) was slightly increased as compared to the bulk ceria (Eg = 3.19 eV). The phytochemicals in the extract reduced the particle size to 3.7 nm ± 0.3 nm, as it is evident from the PSA. FT-IR results confirmed the Ce-O stretching bands by showing the peaks at 452 cm-1. The Raman spectrumshowed a characteristic peak shift for CONPs at 461.2 cm-1. XRD analysis revealed the cubic fluorite structure of the synthesizednanoparticles with the lattice constant, a of 5.415 Å and unit cell volume, V of 158.813 Å3. XPS signals were used to determine the concentration of Ce3+ and Ce4+ in the prepared CONPs and it was found that major amount of cerium exist in the Ce4+ state. HRTEM images showed spherical shaped particles with an average size of 15 nm. Furthermore, the antibacterial activity of the prepared CONPs was evaluated and their efficacies were compared with the conventional antibiotics using disc diffusion assay against a set of Gram positive (G+) bacteria (Staphylococcus aureus, Streptococcus pneumonia) and Gram negative (G-) bacteria (Pseudomonas aeruginosa, Proteus vulgaris). The results suggested that CONPs showed antibacterial activity with significant variations due to the differences in the membrane structure and cell wall composition among the two groups tested.

Open access

P. Maddahi, N. Shahtahmasebi, A. Kompany, M. Mashreghi, S. Safaee and F. Roozban

Abstract

Sol-gel method was successfully used for synthesis of ZnO nanoparticles doped with 10 % Mg or Cu. The structure, morphology and optical properties of the prepared nanoparticles were studied as a function of doping content. The synthesized ZnO:(Mg/Cu) samples were characterized using XRD, TEM, FTIR and UV-Vis spectroscopy techniques. The samples show hexagonal wurtzite structure, and the phase segregation takes place for Cu doping. Optical studies revealed that Mg doping increases the energy band gap while Cu incorporation results in decrease of the band gap. The antibacterial activities of the nanoparticles were tested against Escherichia coli (Gram negative bacteria) cultures. It was found that both pure and doped ZnO nanosuspensions show good antibacterial activity which increases with copper doping, and slightly decreases with adding Mg.

Open access

Damian Wojcieszak, Michał Mazur, Danuta Kaczmarek, Agata Poniedziałek, Piotr Domanowski, Bogumiła Szponar, Aleksandra Czajkowska and Andrzej Gamian

the material [ 11 ]. In the literature there are many, often contradictory, reports on the activity of the various structure phases of TiO 2 . Usually, in the case of antibacterial properties the best efficiency exhibit films with mixed phase, where the content of anatase ranges between 70 and 75 %, while for rutile it is ca. 25 to 30 % [ 4 , 9 ]. The dispersion of these values is most probably a consequence of small differences in crystallite sizes, active surface area, number of defects, level of oxygen adsorption and number of hydroxyl groups on the surface [ 9

Open access

Damian Wojcieszak, Michał Mazur, Danuta Kaczmarek, Agata Poniedziałek and Małgorzata Osękowska

Abstract

The biological and photocatalytic activity of TiO2 and TiO2:Cu in relation to their structure, surface topography, wettability and optical properties of the thin films was investigated. Thin-film coatings were prepared by magnetron sputtering method in oxygen plasma with use of metallic targets (Ti and Ti-Cu). The results of structural studies revealed that addition of Cu into titania matrix (during the deposition process) resulted in obtaining of an amorphous film, while in case of undoped TiO2, presence of nanocrystalline anatase (with crystallites size of 20 nm) was found. Moreover, an addition of cooper had also an effect on surface diversification and decrease of its hydrophilicity. The roughness of TiO2:Cu film was 25 % lower (0.6 nm) as-compared to titania (0.8 nm). These modifications of TiO2:Cu had an impact on the decrease of its photocatalytic activity, probably as a result of the active surface area decrease. Antibacterial and antifungal properties of the thin films against bacteria (Enterococcus hirae, Staphylococcus aureus, Bacillus subtilis, Escherichia coli) and yeast (Candida albicans) were also examined. For the purpose of this work the method dedicated for the evaluation of antimicrobial properties of thin films was developed. It was revealed that Cu-additive has a positive impact on neutralization of microorganisms.

Open access

Beata Zboromirska-Wnukiewicz, Witold Wnukiewicz, Krzysztof Kogut, Jan Wnukiewicz, Roman Rutowski, Jerzy Gosk and Krzysztof Kasprzyk

19 th century, silver compounds were used as a popular medication for tetanus, or rheumatism. At the beginning of the 20 th century, just before the advent of antibiotics, silver was the medicine for fever and infective meningitis. At the end of the 20 th century, due to the development of nanotechnology, silver again, but in a form of nanosilver, found its implementation opportunity in medicine. Anti-bacterial properties of silver depend on its form and the applied dose [2] . Exemplary use of silver in contemporary medicine is its usage for modification of

Open access

Vaibhav Koutu, Lokesh Shastri and M. M. Malik

medical sciences [ 2 , 7 ] and from cosmetics [ 5 ] to antibacterial applications [ 6 ]. Intensive studies have been done on various factors, such as precursor concentrations [ 8 , 9 ], temperature [ 10 , 11 ], duration [ 12 ], surfactant concentration [ 7 ], dopant concentration [ 6 ], solvent medium [ 13 ], pH of reaction mixture [ 14 ] and source of light during synthesis [ 15 ], which individually and collectively affect the shape, size and optical properties of ZnO. Various researchers [ 16 - 18 ] suggested that NaOH concentration plays a vital role in