Preparation of Gemini Surfactant/Conjugated Polymer Aggregates for Enhanced Fluorescence and Bioimaging Application

Conjugated polymers have great potential applications in bioimaging. However, the aggregation of conjugated polymers driven by electrostatic and hydrophobic interactions in aqueous media results in the reduction of photoluminescence quantum efficiency. In present work we synthesized a carboxylate gemini surfactant [sodium 2,6-didodecyl-4-hydroxy-2,6-diaza-1,7-heptanedicarboxylate (SDHC)] to adjust the aggregation behaviors and fluorescence properties of conjugated polymers [anionic poly(2-methoxy-5-propyloxy sulfonate phenylene vinylene) (MPS-PPV) and cationic poly(3-alkoxy-4-methylthiophene) (PMNT)]. This gemini surfactant shows very low critical micellar concentration (CMC) in aqueous solution and forms vesicles above CMC. In neutral and acidic conditions, MPS-PPV combines with the SDHC vesicles mainly via hydrophobic interactions and forms the aggregates in which the photoluminescence quantum efficiency of MPS-PPV is highly enhanced from 0.1% to 27%. As to PMNT, the molecules are located in the bilayer...