Castor oil derivatives in the environmentally friendly one-pot synthesis of silver nanoparticles: application in cysteine sensing

•Castor oil derivatives as reducing and stabilizing agents in the environmentally benign synthesis of silver nanoparticles.•Overwhelmingly faster production of silver nanoparticles upon epoxidation of ricinoleic acid.•Selective detection of cysteine among a variety of aminoacids with silver nanoparticles.