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A simple synthesis method of silver nanoparticles and its application as an active surface-enhanced Raman spectroscopy (SERS) colloid are presented in this work. The photoreduction of AgNO 3 in presence of sodium citrate (NaCit) was carried out by irradiation with different light sources (UV, white, blue, cyan, green, and orange) at room temperature. The evaluation of silver nanoparticles obtained as a function of irradiation time (1-24 h) and light source was followed by UV-visible absorption spectroscopy. This light-modification process results in a colloid with distinctive optical properties that can be related to the size and shape of the particles. The Ag colloids, as prepared, were employed as active colloids in SERS. Pyridine and caffeine were used as test molecules.

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We measured the Raman spectra of ZnO nanoparticles (ZnO-NPs), as well as transition-metal-doped (5% Mn(II), Fe(II) or Co(II)) ZnO nanoparticles, with an average size of 9 nm. A typical Raman peak at 436 cm −1 is observed in the ZnO-NPs, whereas Zn 1−x Mn x O, Zn 1−x Fe x O and Zn 1−x Co x O presented characteristic peaks at 661, 665 and 675 cm −1 , respectively. These peaks can be related to the formation of Mn 3 O 4 , Fe 3 O 4 and Co 3 O 4 species in the doped ZnO-NPs. Moreover, these samples were analyzed at various laser powers. Here, we observed new vibrational modes (512, 571 and 528 cm −1 ), which are specific to Mn, Fe and Co dopants, respectively, and ZnO-NPs did not reveal any additional modes. The new peaks were interpreted either as disorder activated phonon modes or as local vibrations of Mn-, Fe-and Co-related complexes in ZnO.

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In this report is discussed a novel, easy, and general synthesis method to prepare zerovalent iron (ZVI) and copper (ZV Cu) nanoparticles (NPs), from colloid dispersions in an environmental friendly organic solvent, ethylene glycol (EG). Conventional metallic salts are used as nanoparticle precursors; sodium borohydride (NaBH4) is the reducing agent, and triethylamine (TEA) is used as the nanoparticle stabilizer. The chemical changes take place instantaneously under normal reaction conditions. Small iron (alpha-Fe0 phase) and copper (fcc phase) NPs with average diameters of 10.2 +/- 3.3 and 9.5 +/- 2.5 nm, respectively, were obtained. In both cases, the experimental evidence reveals the absence of any metal oxide shell coating the particle surfaces, and their powders remain stable, under aerobic conditions at least for 3 weeks. ZVI NPs were characterized by X-RD, Mössbauer, and Raman spectroscopies and by EELS coupled to HR-TEM. Otherwise, copper NPs were characterized by X-RD, Z-contrast, and HR-TEM. This synthesis pathway is particularly suitable for large-scale and high-quality zerovalent metallic nanoparticle (ZV M NP) production due to its simple process and low cost.

In recent years, infectious diseases, specifically those that are caused by pathogens, have seen a dramatic proliferation due to resistance to multiple antibiotics, opening the colony by opportunistic pathogens. Nanotechnology and tissue engineering have been applied in the development of new antimicrobial therapies, capable of fighting opportunistic infections. In the medical field, research on antimicrobial properties of metal oxide nanoparticles have emerged to find new antimicrobial agents as an alternative against resistant bacteria. The metal oxides, particularly those formed by transition metals are compounds with electronic properties, and most magnetic phenomena involve this type of oxides. Nanoparticlesbased metal oxide properties such as shape, size, roughness, zeta potential and their large surface area, make oxides ideal candidates to interact with bacteria and able to have an antimicrobial effectiveness. The aim of this chapter is to offer an updated panorama about the relationships between the use of metal oxide nanoparticles in the medical field, with an emphasis on their role as antimicrobial agents and the properties that influence their antimicrobial response. In addition, the mechanism of nano-antimicrobial action is described and the importance of using in vitro test methods, adopted by leading international regulatory agencies, that can be used to determine the antimicrobial activity of the metal oxide nanoparticles.