Heating　and　drying　of　the　mixture　of　glutathione-etched　gold　nanoparticles　(Au-SG)　and　β-cyclodextrin　(β-CD)　results　in　the　formation　of　β-CD-capped　and　glutathionate-protected　Au13　nanoclusters　(Au13(SG)8@β-CD).　Their　particle　size,　composition,　and　number　of　gold　atoms　and　the　capping　molecules　were　characterized　by　scanning　electron　microscopy,　fluorescence,　UV–vis　absorption,　FT-IR　spectroscopy　and　mass　spectrometry.　The　fluorescence　of　these　nanoclusters　is　specifically　enhanced　by　the　addition　of　Ag(I)　ions　to　the　aqueous　solution.　This　effect　was　exploited　to　develop　a　selective　and　sensitive　method　for　the　fluorometric　determination　of　Ag(I)　in　water　in　the　concentration　range　between　0.5 nM　and　0.1 μM,　with　a　detection　limit　at　0.3 nM　(at　a　signal-to-noise　ratio　of　3).　©　2014,　Springer-Verlag　Wien.