PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Chapter 1: Synthesis, Characterization and Applications of Gold Nanoparticles
nanoparticles from hydrogen tetrachloroaureate(III) hydrate (HAuCl 4 .3H 2 O) in aqueous
solutions, at ambient temperature, in the absence of any additional reductants or energy input
[95]. This synthesis proceeds quite fast and is environmentally benign and economical since
it involves only water and nontoxic polymers. The gold nanoparticle dispersions formed are
highly stable [96-98]. The thesis provide insight into the role of various components and
solution conditions used in this novel block copolymer-mediated synthesis of gold
nanoparticles on the optimization of various parameters of synthesis such as formation rate,
yield, stability and structure of nanoparticles.
1.7. Summary
Gold nanoparticles have been of recent great interest in the context of its diverse applications
due to their unique optical, electronic, catalytic and chemical properties. The unusual optical
properties of this noble metal, their size-dependent electrochemistry and high chemical
stability have made them the model system of choice for exploring a wide range of
phenomena including self-assembly, bio-labeling, catalysis etc. They can be synthesized by
different ways depending on their applications. All the methods of synthesis of gold
nanoparticles are broadly classified in two categories as top-down and bottom-up methods.
The top-down approach is a subtractive process starting from bulk materials to make
nanomaterials while bottom-up is a controlled additive process that deals with the assembly
of precursor atoms or molecules to make nanomaterials. On the other hand, bottom-up
methods are chemically controllable and non-destructive. Among all bottom-up methods, the
chemical reduction of the metal salt in an aqueous, an organic phase, or two phases, is one of
the most popular routes as nanoparticles of a wide range of sizes and shapes can be prepared
by controlling the reaction conditions. There is variety of techniques for the characterization
of nanoparticles. Spectroscopic techniques (e.g. UV-visible, photoluminescence, IR and
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