Fluorophore-Induced Plasmonic Current: Generation-Based Detection of Singlet Oxygen.

In this work we report the surface-based electrical detection of singlet oxygen using the emerging fluorophore-induced plasmonic current technique. By this method, we utilize the fluorescent "turn on" response of the well-known Singlet Oxygen Sensor Green™ (SOSG™) singlet oxygen (O) fluorescent probe for the generation of fluorophore induced plasmonic current in a silver nanoparticle film. To demonstrate the potential utility of this new technique, a photosensitizing molecule is used to generate O in a solution containing the SOSG™ probe. The resulting change in SOSG™ fluorescence quantum yield and extinction coefficient permits stronger energy transfer from the SOSG™ probe to a proximal silver nanoparticle island film, located in the near-electric field of the probe. This yields an increase in the induced electric current flow, allowing for the detection of the O analyte. To the authors knowledge, this represents the first detection of the reactive oxygen species O utilizing the fluorophore-induced plasmonic current methodology, and even broader the electrical detection of O. This is significant as it opens the possibility for O detection methods which do not require a traditional "photodetector" and associated optics, simplifying the instrumentation over existing fluorescence detection methods and potentially even lowering cost.