'Green' Synthesis of Gold Nanoparticles with Aqueous Extracts of Neem (Azadirachta indica)

Gold nanoparticles of fairly uniform shape and size were obtained by a rapid and reproducible biomimetic synthesis using aqueous extract of neem (Azadirachia indica). The extract served as reducing as well as stabilizing agent in extracellularly synthesizing the nanoparticles at ambient temperatures. At stochiometric ratios differing in a fairly wide band, the nanoparticle formation began immediately on bringing the neem extract and the Au (III) solution together. The synthesis was complete in 24 hours by which time the characteristic plasmon vibration peak of gold nanoparticles stabilized at 557 +/- 1 nm. The paper describes the synthesis process and the associated studies using energy dispersive X-ray spectroscopy (EDAX) and scanning electron microscopy (SEM) techniques. It is brought out that reproducible synthesis of nanoparticles of consistent shapes and sizes is achievable in an environment-friendly manner.