Sensory polymers for electron-rich analytes of biological interest

A water-soluble photooxidizing Amplifying fluorescent polymers (AFP) and its performance in photoinduced electron transfer (PET) based detection of amino acids, neurotransmitters and proteins possessing electron-donating aromatic moieties in aqueous buffer was investigated. AFP is synthesized by the alkaline hydrolysis of its methyl esters and contains a bicyclic ring system which prevents aggregation induced self-quenching that limits many water-soluble AFPs. The absorption and fluorescence spectra of AFP were obtained in water at different pHs. The polymer features a strong absorption band with a strong blue-green fluorescence. The emission spectra are strongly pH-dependent whereas the concomitant changes in the absorption spectra of polymers are minor. The pH response of AFPs fluorescence suggests that the polymer chains are completely soluble at high pH and that aggregated chains are present at low pH.