A　simple　and　selective　luminescence　sensing　method　for　the　cysteine　detection　was　developed　based　on　gold　nanoparticles　modified　by　the　new　ruthenium(II)　complexes.　The　intense　emission　of　the　modified　ruthenium(II)　complexes　was　quenched　efficiently　by　gold　nanoparticles　due　to　the　energy　and　charge　transfer　between　the　ruthenium(II)　fluorophores　and　gold　nanoparticles.　Upon　addition　of　cysteine,　the　emission　of　the　ruthenium(II)　complexes　was　enhanced　significantly　by　the　release　of　the　ruthenium(II)　complexes　from　the　surface　of　the　gold　nanoparticles.　Therefore,　cysteine　could　be　detected　by　this　gold　nanoparticles-ruthenium(II)　complexes　based　probes.　The　synthesis　of　gold　nanoparticles　and　the　modification　based　fluorophores　probed　could　be　accomplished　successfully　within　one　step,　which　simplified　the　preparation　of　luminescence　sensors.　Moreover,　since　metal-to-ligand　charge　transfer　transition　(3MLCT)　emission　band　of　the　ruthenium(II)　complexes　was　in　the　visible　region,　this　approach　was　available　for　biomolecular　sensing　applications,　and　its　relatively　long　life　time　made　it　suitable　for　the　biological　process　studies.　Copyright　©　2011　American　Scientific　Publishers.