biostudies-literatureUnknown8(3)Brox DBeyond their use in analytical chemistry fluorescent probes continuously gain importance because of recent applications of single-molecule fluorescence spectroscopy to monitor elementary reaction steps. In this context, we characterized quenching of a fluorescent probe by different metal ions with fluorescence spectroscopy in the bulk and at the single-molecule level. We apply a quantitative model to explain deviations from existing standard models for fluorescence quenching. The model is based on a reversible transition from a bright to a dim state upon binding of the metal ion. We use the model to estimate the stability constants of complexes with different metal ions and the change of the relative quantum yield of different reporter dye labels. We found ensemble data to agree widely witPloS onee58049https://www.ebi.ac.uk/biostudies/studies/S-EPMC3587577biostudies-literatureEnsemble and single-molecule studies on fluorescence quenching in transition metal bipyridine-complexes.PMC3587577Kiel AHerten DPWorner SJBrox DComba PPernpointner MMartin BfalseEnsemble and single-molecule studies on fluorescence quenching in transition metal bipyridine-complexes.Beyond their use in analytical chemistry fluorescent probes continuously gain importance because of recent applications of single-molecule fluorescence spectroscopy to monitor elementary reaction steps. In this context, we characterized quenching of a fluorescent probe by different metal ions with fluorescence spectroscopy in the bulk and at the single-molecule level. We apply a quantitative model to explain deviations from existing standard models for fluorescence quenching. The model is based on a reversible transition from a bright to a dim state upon binding of the metal ion. We use the model to estimate the stability constants of complexes with different metal ions and the change of the relative quantum yield of different reporter dye labels. We found ensemble data to agree widely wit2013-01-01T00:00:00Z20132025-04-04T10:35:39.502Z2019-03-26T23:13:38ZS-EPMC35875772348396610.1371/journal.pone.0058049