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 1O2. 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.