Highly Sensitive Fluorescence Detection of Hg²⁺ Based on a Water-soluble Conjugated Polymer with Carboxylate Groups

A label-free, highly selective, and highly sensitive fluorescent sensor to detect Hg²⁺ was developed using a water-soluble conjugated polymer with carboxylate groups (poly(2,5-bis(sodium 4-oxybutyrate)-1,4-phenylethynylene-alt-1,4-phenyleneethynylene, PPE-OBS) in this work. The fluorescence of PPE-OBS would be quenched because of the effect among the unique coordination-induced aggregation and electron transfers of PPE-OBS toward Hg²⁺. The linear relationship between the fluorescence intensity and concentration of Hg²⁺ was observed within the range from 6 × 10^-8 to 8 × 10^-5 mol L^-1 (R² = 0.9985), and the limit of detection was 2.10 × 10^-9 mol L^-1. The proposed method was applied to detect Hg²⁺ in environmental water samples, and satisfactory results were obtained.