A　water-stable　and　pH-independent　sensor　for　qualitative　and　quantitative　detection　of　nicotine　in　urine　solution　and　living　cell　was　successfully　developed.　This　material,　named　MB@UiO-66-NH2,　can　be　synthesized　by　encapsulating　methylene　blue　(MB)　with　a　well-known　metal-organic　framework　(MOF)　UiO-66-NH2　through　a　simple　impregnation　method.　The　fluorescence　intensity　of　the　system　was　significantly　enhanced　when　a　certain　amount　of　nicotine　was　added.　In　the　meanwhile,　MB　is　reduced　by　reductive　nicotine　to　form　leucomethylene　blue　(LB).　The　proposed　sensor　displayed　excellent　selectivity　and　sensitivity　toward　nicotine　with　limit　of　detection　(LOD)　of　0.98　μM,　which　is　comparable　or　even　better　than　that　of　the　electrochemistry　detecting　methods　for　nicotine.　The　obvious　enhancement　and　blue　shift　of　the　emission　arise　from　the　photoinduced　electron　transfer　(PET)　from　LB　to　the　UiO-66-NH2.　The　photophysical　properties　and　the　sensing　applications　of　MB@UiO-66-NH2　suggest　that　this　composite　can　be　acted　as　a　sensitive,　selective,　recyclable,　and　fluorogenic　sensor　for　nicotine　determination　in　urine　solution　and　living　cell.　Copyright　©　2019　American　Chemical　Society.