Techniques for metal enhanced fluorescence include determining a calibration curve that relates concentration of a particular analyte to at least one of intensity or lifetime of fluorescent emissions at a plasmonic substrate in response to incident light, for a plurality of known concentrations of the particular analyte mixed with a reagent. The reagent comprises a detection molecule. A concentration of the particular analyte in a vicinity of a cell in a sample is determined directly from the calibration curve and measurements, in response to the incident light, of at least one of intensity or lifetime of fluorescent emissions at the plasmonic substrate in contact with the cell and reagent.
