Copper nanoparticles were synthesized by thermal decomposition using copper chloride, sodium oleate, and phenyl ether as solvent agents. The formation of nanoparticles was evidenced by the X-ray diffraction and transmission electron microscopy. The peaks in the XRD pattern correspond to the standard values of the face centered cubic (fcc) structure of metallic copper and no peaks of other impurity crystalline phases were detected. TEM analysis showed spherical nanoparticles with sizes in the range of 4 to 18 nm. The antibacterial properties of copper nanoparticles were evaluated in vitro against strains of Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activity of copper nanoparticles synthesized by thermal decomposition showed significant inhibitory effect against these highly multidrug-resistant bacterial strains.

The preparation and characterization of hcp and fcc Ni and Ni/NiO nanoparticles is reported. Ni and Ni/NiO nanoparticles were obtained starting from a precursor material prepared using a citric assisted Pechini-type method and, then, followed by a calcination of the precursor in air at either 400 or 600°C for different times. The precursor was analyzed using thermogravimetric and differential thermal methods (TGA-DTA), and the resulting nanoparticles were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and vibrational sample magnetometry. Nanoparticles showed a phase transformation for Ni from hcp to fcc and/or to fcc NiO structure as the calcination time increased. The influence of the phase transition and the formation of NiO on the magnetic properties of the samples are discussed.

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Surface-modified silver nanoparticles (NAg) were encapsulated into a polystyrene (PS) matrix by in situ miniemulsion polymerization. Silver nanoparticles were modified with 3-aminopropyltrimethoxysilane (APTMS) that acts as a coupling agent and costabilizer in the polymerization reaction. The PS-Nag nanocomposites synthesized via miniemulsion polymerization were made at two different concentrations of the initiator (0.7 and 2.5 g/L in H2O); at higher concentration of the initiator the conversion and efficiency of encapsulation increases, and the average particle size decreases. The PS-NAg composites showed excellent antimicrobial performance toward bacteria such as Escherichia coli and Staphylococcus aureus.