Based on graphene oxide and using a fluorescent molecule modified single-stranded DNA( ss DNA) as a probe,the specific binding between Ag+ion and C-C mismatched base pair in duplex DNA has been studied by fluorescence spectroscopy and circular dichroism spectra. Moreover,a fluorescent method for detecting Ag+ion has been established. Fluorescence spectroscopy showed Ag+ion could stabilize the C-C mismatched base pair in double-stranded DNA,and the fluorescence of fluorescent marker on the DNA which was quen...