A　novel　squaraine　dye　(SQ-1)　was　developed　and　its　chemosensor　behavior　toward　various　metal　ions　was　explored.　SQ-1　exhibited　selectivity　and　sensitivity　to　Hg2+　and　Ag+　compared　to　other　metal　ions,　and　it　can　detect　Hg2+　and　Ag+　by　use　of　an　EDTA　reversible　experiment.　More　importantly,　the　SQ-1-Hg2+　complex　can　also　serve　as　a　colorimetric　and　fluorescent　turn-on　sensor　for　thiol-containing　biomolecules,　and　a　dynamic　measuring　range　could　be　obtained　by　adjusting　the　concentration　of　Hg2+.　(C)　2012　Elsevier　B.V.　All　rights　reserved.