Smart gold nanosensor for easy sensing of lead and copper ions in solution and using paper strips

A smart gold nanosensor, Au-TA-DNS is designed that can rapidly detect very low concentrations of Pb2+ and Cu2+ ions. The nanosensor develops a visible blue colour in solution and on paper strips, because of the formation of nanoparticle aggregates upon binding with metal ions. Due to the presence of dansyl fluorophore, Au-TA-DNS also exhibits significant fluorescence quenching following Pb2+ and Cu2+ binding in aqueous medium, which is proportional to the concentration of ions. Both colorimetric and fluorometric analyses are very much selective for lead and copper ions with a detection limit of <= 10.0 ppb. The paper based sensing method has the advantage of cost-effectiveness and would be useful for wide range of field-test applications such as water quality monitoring process.