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Colloidal gold is a sol or colloidal suspension of nanoparticles of gold in a fluid, usually water. [1] The colloid is coloured usually either wine red (for spherical particles less than 100 nm) or blue-purple (for larger spherical particles or nanorods). [2]
Gold clusters, a part of cluster chemistry, is a term used to describe molecular clusters of gold or larger colloidal particles. Both types can described as nanoparticles, with diameters of less than one micrometer. [1] Gold nanoclusters have, despite intense efforts, as yet no commercial applications.
Gold nanoparticles can be purchased or synthesized via a variety of methods. [12] Several strategies exist for functionalizing gold nanoparticles with single-stranded DNA; one of the most commonly utilized strategies involves introducing thiol-terminated DNA to a solution of gold nanoparticles and gradually increasing the concentration of a salt, like NaCl.
A nanoshell, or rather a nanoshell plasmon, is a type of spherical nanoparticle consisting of a dielectric core which is covered by a thin metallic shell (usually gold). [1] These nanoshells involve a quasiparticle called a plasmon which is a collective excitation or quantum plasma oscillation where the electrons simultaneously oscillate with ...
Nanoparticles can take on a non-spherical shape, such as this star-shaped gold nanoparticle. Morphology refers to the physical shape of a particle, as well as its surface topography, for example, the presence of cracks, ridges, or pores. Morphology influences dispersion, functionality, and toxicity, and has similar considerations as size ...
An SEM image of epitaxial nanowire heterostructures grown from catalytic gold nanoparticles. There are two basic approaches to synthesizing nanowires: top-down and bottom-up. A top-down approach reduces a large piece of material to small pieces, by various means such as lithography, [5] [6] milling or thermal oxidation.
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. [1] [2] The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions.
Not all the clusters are stable. The stability of nanoclusters depends on the number of atoms in the nanocluster, valence electron counts and encapsulating scaffolds. [22] In the 1990s, Heer and his coworkers used supersonic expansion of an atomic cluster source into a vacuum in the presence of an inert gas and produced atomic cluster beams. [21]