The most precious role yet for gold and silver could be in the field of water purification.Two scientists from the Indian Institute of Technology, Madras, T. Pradeep and A. Sreekumaran Nair, have patented technology to use gold and silver nanoparticles to filter endosulfan, malathion and chlorpyrifos pesticides from water. The technology exploits the ability of the nanoparticles to bind residual pesticides from flowing water through adsorption.