Metallic nanomaterials

There is no doubt that metallic nanoparticles that have defined sizes and shapes will become key components of a number of novel, highly sophisticated products, the prototypes of which are currently emerging from the industrial R D departments. The outlook is promising for the industrial production of defined 1.4nm metal clusters for use as single electron switches or transistors, for the cost-effective fabrication of ultrapure metallic nanomaterials needed for dye solar cells or sensors, and for the reproducible production of (particularly) efficient and durable... 

An important field of development is the batched flow production of metal nanoclusters attached to biomolecules such as DNA under GMP laboratory standards. This conjures up hopes of applying metallic nanomaterials coupled with drugs, antibodies, or with oligonucleotides for cell-specific cancer diagnosis and therapy. With the help of such nanometallic tools, it can be expected that diseases or predispositions to diseases will be diagnosed earlier with the help of nanodrugs than is possible at present. 

However, the low sensitivity problem of Raman spectroscopy can be overcome by the optical phenomenon called surface-enhanced Raman scattering (SERS), which originates from the conjugation of molecules with the novel metal nanomaterials such as gold or silver. After the first report of such a phenomenon in 1974 [16], several techniques were developed for a wide variety of applications. Current development in nanotechnology has accelerated the researches about SERS to realize accurate, sensitive, selective, and practical sensing platform in several areas including biomolecular detection. 

The dissolution rate and stability ofNMs over time is another crucial issue. Kittler et al. [32] have shown that the release of silver ions from a dispersion of silver nanoparticles in water, and consequently the toxicity towards human mesenchymal stem cells, increases significantly with time. In addition, the temperature and the nature of the biological medium (e.g., the presence of salts or biomolecules) are important factors influencing the dissolution of metal nanomaterials. Unfortunately, measurement of the dissolution... 

Hybrid materials have obtained a large interest in nanomaterials research and, recently, lanthanide-based materials have been combined with magnetic and metal nanomaterials in order to construct nanoparticles with advanced features... 

In most cases, nanostructures possess an inorganic core of metal, carbon, or semiconductor material. A few examples of nanostructured coatings based on pure conductive polymers [37] have also been reported in the literature, as better described in Sect. 6.5. Most metal nanomaterials consist of noble metals, although Ag and Cu have also been reported [8, 11, 13-15, 17-20, 23, 24, 26-28]. For electroanalytical applications, NPs constitute the most common nanostructures, followed by nanowires [38, 39]. Although the former appear spherical, they are actually a polyhedral shape (Fig. 6.1). 

Another problem limiting the application of nanociystalline materials is prep>aration of nanocrystalline alloys. Currently, the bulk metallic nanomaterials can only be prepared at the laboratory scale, usually by compacting prepared nanocrystalline powders. However, consolidation of the nanopowders into bulk materials needs high temperature and pressure which may considerably coarsen the structure. Because of this difficulty, surface nanocoating has been considered a potential industry application. Nanocrystalline costing are often prepared by chemical vapour deposition (CVD), physical vapour deposition (PVD), electrochemical deposition, electro-spark deposition, and laser and electron beam surface treatment. 

Hu, X. and Dong, S. (2008) Metal nanomaterials and carbon nanotubes-synthesis, functionalization and potential applications towards electrochemistry. J. Mater. Chem., 18, 1279-1295. 

Among the multitude of anisotropic noble metal nanomaterials synthesized, an exciting addition from the Indian context is the work by Murali... 

The electrochemical route for the synthesis of metal nanomaterials foresees the electrochemical oxidation-reduction of metal complexes accomplished in a simple two- [76] or three- [77] electrode t3 e cell. The electrodes are immersed in an electrolytic solution basically composed of soft-templating molecules which operate in the reaction domain both as shape-inducing reagents stabilizing and delineating the nanoparticles shape and size and furthermore as supporting electrol3 e [76, 78, 79]. A two-electrode setup is sketched in Fig. 10.3a. 

This section specifically reviews wet-chemical hydrothermally synthesized single- and bi-component metal NCs whose growth is promoted by microwave irradiation. Ordinarily, dealing with metallic NCs is mainly synonymous of Ag or Au NC growth, two widespread materials which share a realistic technical interest due to their widely effective applicability in nanotechnology [135, 220]. The two noble metals show similar fee crystal structure as well as crystallographic lattice constants. Further examples of metallic nanomaterials will be presented and discussed in detail. 

Nuclear-based Metallomics in Metallic Nanomaterials Nanometallomics... 

Nanometallomics will study (1) quantification of nano-scaled metal(loid)s and metallic nanomaterials of interest in biological systems (2) distributions of studied nano-sealed metal(loid)s and metallie nanomaterials in biological systems (3) the speciation of given nano-sealed metal(loid)s (4) the structural analysis of the nanometallome (5) the elueidation of reaetions and related mechanisms of nanometallome (6) metabolisms of nanometallome and (7) the specific nano-scaled metal(loid)-assisted funetion bioseienees in medieine, environment science, food science, agrieulture, toxieology, and bioehemistry. 

Corresponding to the objects of elementomics study, different analytieal techniques can be used to reach these goals. The applieation of advaneed nuclear analytical techniques on metalloproteomies study has been reviewed by Gao et alP In the following parts, nuelear analytieal teehniques, whieh ean achieve some of the above goals of nanometallomies, espeeially analytieal techniques for characterization, elemental quantifieation and distribution, and structural analysis of metallic nanomaterials, will be introdueed. 

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