ABSTRACT
Gold nanoparticles have size-dependent optical properties that differ from those of semiconductors but are extremely useful for imaging and sensing applications. Gold nanoparticles are among the easiest nanomaterials to synthesize: Reduction of gold salts by a selected reducing agent yields particles soluble in water or organic solvent as desired. e size of the particles during synthesis is controlled by changing the amount of reducing agent present in the reaction. Different particle sizes appear different colors because of changes in the plasmon resonance frequency caused by damping of electronic oscillations as particles become smaller. e characteristic color of 5-nm gold particles is a striking ruby red. Larger particles appear blue. e purpose of this exercise is to synthesize gold nanoparticles by sodium citrate reduction in aqueous solution. is
results in gold nanoparticles about 15 nm in diameter, capped with citrate.
