Green synthesis of biopolymer-silver nanoparticle nanocomposite: An optical sensor for ammonia detection

► Green synthesis of silver nanoparticle by using Cyamopsis tetragonaloba. ► The polysaccharide act as capping and reducing agent with high stability. ► Nanoparticles with crystallite size of 8 nm were obtained. ► Silver nanoparticle is used for room temperature optical ammonia sensor. ► It shows high sensitivity, low detection limit and fast response.