Highly sensitive fluorescent sensor for mercury (II) ion based on layer-by-layer self-assembled films fabricated with water-soluble fluorescent conjugated polymer

In this paper, a simple and sensitive Hg (II) sensor based on the water-soluble fluorescent conjugated polymer multilayer films was developed. The multilayer films were fabricated successfully utilizing layer-by-layer self-assembly technology via the electrostatic interaction between polycation electrolyte PDDA and sulfonic group anion surrounded conjugated polymer PPESO3. In the presence of Hg (II) ion, the photoluminescence (PL) of PDDA/PPESO3 multilayer films quenched effectively without obvious maximum PL emission wavelength shift. The PL intensity ratio I0/I (I0 and I are the fluorescence intensity of PDDA/PPESO3 multilayer films in the absence and presence of Hg(II) ion, respectively) was proportional to the concentration of Hg (II) in the concentration ranges of 2.0 × 10−7 to 3.0 × 10−5 mol L−1. The detection limit (LOD) for Hg (II) was 1.0 × 10−7 mol L−1. The proposed film sensor was successfully applied for the determination of Hg (II) in several water samples with satisfactory reproducibility and accuracy. This work may provide a common platform for the further development of various solid-state portable devices.