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Synthesizing nanoparticles by mimicking nature
Citation:
Varma, R. Synthesizing nanoparticles by mimicking nature. McGraw-Hill Yearbook of Science & Technology 2015, 1st Edition. McGraw-Hill Education, New York, NY, ISBN:97800718357:online only, (2014).
Impact/Purpose:
Submitted as a contributory article to the McGraw-Hill Yearbook of Science and Technology.
Description:
As particulate matter with at least one dimension that is less than 100 nm, nanoparticles are the minuscule building blocks of new commercial products and consumer materials in the emerging field of nanotechnology. Nanoparticles are being discovered and introduced in the marketplace at a very fast pace. Also, commercial interest in nanotechnology has significantly increased, translating into more than a multibillion-dollar investment from public and private sources. Among several unique properties, nanoparticles have an exceptionally large surface area–to-volume ratio, which is the most important of the characteristics that are responsible for their widespread use in an array of industries. Unfortunately, their small size and corresponding high surface area often create a number of problems. For instance, the outer layer of atoms may have a different composition, and therefore a different chemistry, from the rest of the particle. Furthermore, nanoparticle surfaces are sensitive to changes in redox conditions, pH, ionic strength, and the types of microorganisms present. The synthesis of metal nanoparticles has been the subject of intense research, primarily because of their unique properties and their potential applications from a technological point of view. The optical, magnetic, electronic, and catalytic properties of these materials depend on their morphology and size distribution. Noble-metal nanoparticles are of particular interest because of their close-lying conduction and valence bands, in which electrons move freely. These free electrons generate surface plasmon bands dictated by the particles' size, shape, and immediate surroundings. Notably, the fascinating color of the noble-metal nanoparticles depends on both the size and the shape of the particles as well as the refractive index of the encasing medium.
