A highly selective and sensitive on-off sensor for silver ions and cysteine by light scattering technique of DNA-functionalized gold nanoparticles.

DNA-functionalized gold nanoparticles are shown to act as a light-scattering switch. Ag(+) ion turns on the switch through the DNA-Au NPs conjugates based on the formation of cytosine-Ag(+)-cytosine base pairs, whereas cysteine turns off the light-scattering signal because it competitively binds to Ag(+). This journal is © The Royal Society of Chemistry 2011