Fluorescence‐Amplifying Detection of Hydrogen Peroxide with Cationic Conjugated Polymers, and Its Application to Glucose Sensing

A highly sensitive hydrogen peroxide probe that takes advantage of the amplified fluorescence quenching of conjugated polymers has been developed. The cationic conjugated polymer, poly(9,9‐bis(6′‐ N , N , N ‐trimethylammonium‐hexyl) fluorene phenylene) (PFP‐NMe 3 + ) and peroxyfluor‐1 with boronate protecting groups (Fl‐BB) are used to detect H 2 O 2 optically. Without the addition of H 2 O 2 , the absence of electrostatic interactions between the cationic PFP‐NMe 3 + and the neutral Fl‐BB keeps the Fl‐BB well separated from the PFP‐NMe 3 + , and no fluorescence quenching of the PFP‐NMe 3 + occurs. In the presence of H 2 O 2 , the formation of the anionic quencher, fluorescein, by specific reaction of the Fl‐BB with H 2 O 2 results in strong electrostatic interactions between the PFP‐NMe 3 + and the fluorescein, and therefore efficient fluorescence quenching of the PFP‐NMe 3 + occurs. The absorption of fluorescein overlaps the emission of PFP‐NMe 3 + , which encourages fluorescence resonance energy transfer (FRET) from the PFP‐NMe 3 + to the fluorescein. The H 2 O 2 probe has very good sensitivity, with a detection range of 15 to 600 nM. Since glucose oxidase (GOx) can specifically catalyze the oxidation of β‐ D ‐(+)‐glucose to generate H 2 O 2 , glucose detection is also realized with the H 2 O 2 probe as the signal transducer.