Multi-head cationic siloxane based “turn on” fluorescent system for selective detection of perfluorooctanoic sulfonate (PFOS)

Abstract

Perfluorooctane sulfonate (PFOS) has attracted more and more attention because of its persistence, bioaccumulation and potential ecotoxicity. Although the electrostatic interaction between surfactant and dye has been used for PFOS detection, there still exist a problem in selectivity and some phenomenon also should be explored. Herein, two types of multi-head cationic siloxanes (M1 and D1) based “turn on” fluorescent system were designed for PFOS detection and were further used for exploring interaction between surfactant and dye. Cationic group (quaternary ammonium salt) was introduced into siloxane via thiol-ene click reaction. Two types of multi-head siloxanes with different amounts of cationic group and steric structure were obtained and showed a high selective detection for PFOS. More important, we further explored the possible response mechanism by contracting fluorescence behavior of three types of cationic molecules (single-head, two-head, and four-head cationic group) and speculated the high selectivity was derived from the synergistic effect between electrostatic interaction and steric hindrance. Furthermore, the exploration about surfactant-dye interaction in this work provide a deeper understanding for electrostatic action and its application.