This chapter summarizes the basic information about elementary characteristics and technology of preparation of noble metal nanoparticles. The introduction gives some basic information on the history of development in this area, especially in terms of dimensionality of metal nanostructures and their possible applications.The first subsection is devoted to the preparation and characterization of Au, Ag, Pt, and Pd nanoparticles (NPs), which were synthesized by direct metal sputtering in liquid propane-1,2,3,-triole (glycerol). This method provides an interesting alternative to time-consuming, wet-based chemical synthesis techniques. Moreover, the suggested technique allows targeted variation of metal nanoparticle size, which is demonstrated in detail in case of AuNPs by variation of capturing media temperature. Nanoparticle size and shape were studied by transmission electron microscopy and dynamic light scattering. Optical properties of nanoparticle solution were determined by measuring its UV–Vis spectra. Concentration of metal nanoparticles in prepared solutions was determined by atomic absorption spectroscopy. Antibacterial properties were tested against two common pollutants (Escherichia coli, a Gram-negative bacteria, and Staphylococcus epidermidis, a Gram-positive bacteria). In the presence of Ag nanoparticles, the growth of E. coli and S. epidermidis was completely inhibited after 24 h. Any growth inhibition of E. coli was observed neither in the presence of “smaller” (4–6 nm, AuNP4–6) nor “bigger” (9–12 nm, AuNP8–12) AuNPs during the whole examination period. AuNP4–6, but not AuNP8–12, was able to inhibit the growth of. S epidermidis. We also observed significant difference in biological activities of Pt and PdNPs. More specifically, PdNPs exhibited considerable inhibitory potential against both E. coli and S. epidermidis, which was in contrast to ineffective PtNPs. Our results indicate that Ag, Pd, and partially AuNPs have high potential to combat both Gram-positive and Gram-negative bacterial strains.The second subsection describes the effort to anchor metal nanoparticles onto polyethyleneterephthalate (PET) carrier. Two different procedures of grafting of polymeric carrier, activated by plasma treatment, with Au and AgNPs are described. In the first procedure, the PET foil was grafted with biphenyl-4,4’-dithiol (BPD) and subsequently with Au and AgNPs. In the second one, the PET foil was grafted with Au and AgNPs previously coated by the same BPD. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Au and AgNPs were characterized by UV–Vis spectroscopy. In case of both types of nanoparticles, the first procedure was found to be more effective. It was proved that the BPD was chemically bonded to the surface of the plasma-activated PET and it mediates subsequent grafting of the AuNPs.
Part of the book: Nanoparticles Technology
Noble metals in their diverse nanoforms bring revolution to many fields of science and technology, as they provide unique properties over their bulk counterparts. Thanks to these completely unprecedented properties, commercial sphere pressure is growing to use them in everyday life. Unfortunately, one of the issues that are subject to dramatic changes is the reactivity of these structures. This may have often fatal consequences to the living organisms. Due to the fact that the mechanism of action of metal nanostructures on living organisms is not yet fully elucidated even in the case of the most studied noble metals such as gold and silver, it is necessary to continue intensively in their research, characterization and categorization. The main prerequisite for the undistorted study of interactions of nanostructures with living organisms is the use of suitable methods of their preparation. Within this context, this chapter attempts to summarize current knowledge form the field of synthesis of metal nanoparticles, layers, wires, and other nanostructures, especially regarding novel techniques of their preparation and extend them by our own results in this area, in the context of their biological properties. More specifically, antibacterial efficacy and potential cytotoxicity of those structures are thoroughly addressed.
Part of the book: Noble and Precious Metals