Green synthesis of polysaccharide/gold nanoparticle nanocomposite: An efficient ammonia sensor

► Green synthesis of gold nanoparticles using guar gum. ► Gold nanoparticle is characterized by using UV-vis, XRD, SEM and TEM. ► Gold nanoparticle is used for room temperature optical ammonia sensor. ► It show high sensitivity, ultra low detection limit and fast response.