Facile fabrication of a cost-effective, water-soluble, and electrosynthesized poly(9-aminofluorene) fluorescent sensor for the selective and sensitive detection of Fe(III) and inorganic phosphates

Water-soluble poly(9-aminofluorene) (P9AF) was facilely synthesized by the direct electropolymerization of commercially available monomer 9-aminofluorene in boron trifluoride diethyl etherate, and its preliminary application as a fluorescent chemosensor for the highly selective and sensitive detection of Fe(III) and inorganic phosphates (Pi) in an organic buffer 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) (pH 7.0) was investigated. The one-step electrosynthesized P9AF with high quality and water-solubility possessed good fluorescence properties. P9AF was employed to sense Fe(III) in aqueous solution, displaying high selectivity, pronounced sensitivity, low detection limit, and fast response. On binding to Fe(III), exceptional fluorescence quenching of P9AF occurred, demonstrated by a >94% reduction in the fluorescence intensity. P9AF–Fe(III) complex exhibited high sensitivity and rapid response to Pi with turn-on fluorescence. The working mechanism was proposed and confirmed by transmission electron microscopy. The determination of Fe(III) in real samples and the interaction of P9AF with Fe(III) and Pi in living cells were investigated with satisfying results, showing that the cost-effective, water-soluble, and electrosynthesized P9AF has potential application in biological system and environment.