Ratiometric Sensing of Hydrogen Peroxide Utilizing Conformational Change in Fluorescent Boronic Acid Polymers

We demonstrate that the copolymers containing boronic acid and pyrene units can be utilized for the fluorometric sensing of hydrogen peroxide (H₂O₂) in aqueous solutions. The copolymer exists in a relatively extended conformation in the absence of H₂O₂, whereas the polymer chain is contracted by the reaction of boronic acid moieties with H₂O₂ to form phenol groups. This conformational change induces aggregation of the originally isolated pyrene groups. As a result, relative intensity of excimer emission with respect to monomer emission increases with H₂O₂ concentration. Accordingly, the present methodology enables us to measure H₂O₂ by means of ratiometric fluorescence change in the range of 0-30 μM.