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 (PC) technique. By this method, we utilize the fluorescent "turn on" response of the well-known singlet oxygen sensor green (SOSG) singlet oxygen (¹O₂) fluorescent probe for the generation of fluorophore-induced PC in a silver nanoparticle film. To demonstrate the potential utility of this new technique, a photosensitizing molecule is used to generate ¹O₂ 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 ¹O₂ analyte. To the author's knowledge, this represents the first detection of the reactive oxygen species ¹O₂ utilizing fluorophore-induced PC methodology and even broader electrical detection of ¹O_2. This is significant as it opens the possibility for ¹O₂ detection methods which do not require a traditional "photodetector" and associated optics, simplifying the instrumentation over existing fluorescence detection methods and potentially even lowering the cost.