A report on a water-sol. photooxidizing amplifying fluorescent polymer (AFP) and its performance in photoinduced electron transfer (PET) based detection of amino acids, neurotransmitters, and proteins possessing electron-donating arom. moieties in aq. buffer is presented. This report has shown that a water-sol. photooxidizing AFP could serve as a PET-based sensor for amino acids, neurotransmitters and proteins with electron-donating arom. compds. in aq. media. The results show that the quenching efficiency is strongly dependent on electrostatic interaction of the anionic polymer and quencher as well as hydrophobic and electron-transfer interactions between the polymer chains and quencher. [on SciFinder(R)]