A new fluorescence sensor is developed for simultaneous detection of Hg^2＋ and Ag^＋. During the detection process,Hg^2＋ forms complexes with the fluorescent dye rhodamine B isothiocyanate（RBITC） modified onto the surface of gold nanoparticles（Au NPs）,resulting in RBITC＇s displacement from the surface of Au NPs and the recovery of fluorescence. Meanwhile,Ag^＋ forms ＂C-Ag^＋-C＂ complex with C-rich 5-carboxyfluorescein（FAM）-ss DNA modified onto the surface of Au NPs,which keeps the fluorescent dye FAM close to the Au NPs and results in quench of fluorescence. The experimental results show a wide linear range and a good sensitivity. The limit of detection is 1.06 nmol/L for Ag^＋ and 0.48 nmol/L for Hg^2＋. This detection method is not only easy to operate but also efficient.
