Naked-eye detection of pollutants through visible-light-induced polymerization

I developed an approach for signal amplification using a visible-light-induced polymerization, initiated by a switchable photoredox catalyst. Fluorescein derivatives as photoredox catalysts are able to initiate photopolymerization and rapidly form hydrogel under visible light. Moreover, they exhibit selective chromogenic and fluorogenic responses to target pollutants in the visible light. In this work, we employed fluoresceins as a switchable photoredox catalyst for the generation of a colorimetric readout of either Hg(II) ions or H2O2 via the visible-light-induced polymerization of N-vinylpyrrolidone (VP) and poly(ethylene glycol) diacrylate (PEGDA) under aerobic conditions. This photopolymerization-based signal amplification yielded about 20 times higher sensitivity than UV-Vis spectrometry and enabled the naked-eye detection of Hg(II) ions with concentrations down to 0.1 μM. In addition, 10 μM of the catalyst allows a successful detection of H2O2 down to 20 μM. We envision that this strategy will be highlighted by mechanistic elucidation of photoredox catalysis and colorimetric sensing of hazardous substances.