Based　on　the　adsorption　of　a　metal-organic　framework　(MOF)　to　DNA,　a　fluorescent　biosensor　for　H5N1　antibodies　has　been　developed.　In　this　system,　a　short　oligonucleotide　was　modified　with　the　fluorescent　dye　5′6-FAM　(5′6-carboxyfluorescein)　as　the　fluorescent　DNA　probe.　With　the　introduction　of　a　MOF　aqueous　solution,　the　DNA　probe　can　be　adsorbed　by　the　MOF　and　the　fluorescence　of　the　dye　will　be　quenched　by　the　MOF.　Subsequently,　exonuclease　I　(Exo　I)　is　employed　to　specifically　hydrolyze　the　DNA　probe　at　the　3′-terminus　and　the　fluorescent　dye　FAM　is　released　from　the　MOF,　which　results　in　recovery　of　the　fluorescence.　If　the　3′-ends　of　the　DNA　probe　are　linked　to　H5N1　antigens,　which　can　specifically　recognize　the　H5N1　antibody,　the　hydrolysis　of　Exo　I　would　be　inhibited,　so　the　fluorescence　of　the　system　would　not　recover.　The　fluorescence　is　related　to　the　logarithm　of　the　H5N1　antibody　concentration　in　the　range　1.0　×　10-6-5.0　×　10-9　mol　L-1　with　a　detection　limit　of　1.6　×　10-9　mol　L-1　(S/N　=　3).　The　proposed　method　has　been　applied　to　detect　the　H5N1　antibody　in　serum　samples　with　satisfactory　results.　©　The　Royal　Society　of　Chemistry　2013.