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

<jats:title>Abstract</jats:title><jats:p>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′‐<jats:italic>N</jats:italic>,<jats:italic>N</jats:italic>,<jats:italic>N</jats:italic>‐trimethylammonium‐hexyl) fluorene phenylene) (PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup>) and peroxyfluor‐1 with boronate protecting groups (Fl‐BB) are used to detect H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> optically. Without the addition of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>, the absence of electrostatic interactions between the cationic PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup> and the neutral Fl‐BB keeps the Fl‐BB well separated from the PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup>, and no fluorescence quenching of the PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup> occurs. In the presence of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>, the formation of the anionic quencher, fluorescein, by specific reaction of the Fl‐BB with H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> results in strong electrostatic interactions between the PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup> and the fluorescein, and therefore efficient fluorescence quenching of the PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup> occurs. The absorption of fluorescein overlaps the emission of PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup>, which encourages fluorescence resonance energy transfer (FRET) from the PFP‐NMe<jats:sub>3</jats:sub><jats:sup>+</jats:sup> to the fluorescein. The H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> 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‐<jats:sc>D</jats:sc>‐(+)‐glucose to generate H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>, glucose detection is also realized with the H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> probe as the signal transducer.</jats:p>