Inorganic nanoparticles are inorganic materials in which the particle diameter is in the 1-100-nm regime. If we classify materials according to their electronic properties and assign them either to metals, semiconductors, or insulators, then metals and semiconductors are by far more interesting to contemplate on the nanoscale. Fundamentally, the mean free path of an electron in a metal at room temperature is ~10-100 nm, and one would predict that as the metallic particle shrinks to this dimension, unusual effects should be observed. In the case of metal nanoparticles, optical properties can be tuned extensively by the size, shape, aggregation, and local environment of the particle. For gold and silver, multiple plasmon bands that give rise to visible colors can occur in the visible and into the infrared for various geometries. Quantum dots are inorganic semiconductor nanoparticles that have a diameter in the 1-10 nm range, coincident with their respective excitonic Bohr radii. These materials are highly photoluminescent, resistant to photobleaching compared to organic fluorophores and their bandgap energies are exquisitely
tunable with particle diameter, based on quantum confinement effects.

           This presentation highlights work from its authors’ laboratories on the synthesis, growth
mechanism, physical properties, reactivity, and applications of silver, gold and platinum nanoparticles and quantum dots. This includes nanomaterials with various designs, geometries and compositions prepared by wet chemical synthesis approaches. These metallic nanoparticles are used as templates for creation of
complex and ordered engineered nanomaterials with tailored and tunable structural, optical and surface properties. This consists of core-shell, nano-peapods, fluorescent, solid or hollow nanocomposites that can be used for a plethora of applications including (bio)chemical sensing, imaging, molecular-scale
electronics, environmental implications and energy production applications.