Enteric bacterial human pathogens, i.e., Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Klebsiella pneumoniae, are the major cause of diarrheal infections in children and adults. Their structure badly affects the human immune system. It is important to explore new antibacterial agents instead of antibiotics for treatment. This project is an attempt to explain how gold nanoparticles affect these bacteria. We investigated the important role of the mean particle size, and the inhibition of a bacterium is dose-dependent. Ultra Violet (UV)-visible spectroscopy revealed the size of chemically synthesized gold nanoparticle as 6–40 nm. Atomic force microscopy (AFM) analysis confirmed the size and X-ray diffractometry (XRD) analysis determined the polycrystalline nature of gold nanoparticles. The present findings explained how gold nanoparticles lyse Gram-negative and Gram-positive bacteria.

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The structural and magnetic properties of ferromagnetic nanotubes fabricated by a low cost electrodeposition method are investigated. The fabrication of various elemental ferromagnetic materials are described, such as Fe, Co, and Ni, and ferromagnetic alloys, such as NiFe, CoPt, CoFeB, and CoCrPt nanotube arrays, in aluminum oxide templates and polycarbonate membranes with different diameters, wall thicknesses, and lengths. The structural, magnetic, and magnetization reversal properties of these nanotubes are investigated as a function of the geometrical parameters. The angular dependence of the coercivity indicates a transition from the curling to the coherent mode for the ferromagnetic nanotubes. The results show that nanotube fabrication allows the outer and inner diameter, length, and thickness of the nanotubes to be tuned systematically. The magnetization processes of ferromagnetic nanotubes are influenced by the wall thickness.

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