Synthesis and photo-physical properties of polymeric soft materials and its application in FRET based DNA sensor

Abstract

Water-soluble conjugated polyelectrolytes (CPs) an ideal advanced soft materials have attracted considerable attention as an optical platform in chemical and biological assays for nucleic acids, proteins, enzyme activities and physiological metal ions. From the viewpoint of detection sensitivity, CPs-based assays benefit from their light-harvesting properties via collective response of optical units along the polymer backbone. In the present investigation we have successfully synthesized a cationic conjugated polymer via Suzuki copolymerization and successive quaternization. In order to enhance its optical property for efficient biosensor materials, a polymer-surfactants micellar complex approach has been made. In water, the molar absorptivity and fluorescence quantum efficiency of cationic poly(fluorene-co-phenylene) (c-PFP) were substantially increased in the presence of nonionic surfactants. About 400% enhancement of the FRET signal was measured in c-PFP/ssDNA-Fl with Brij 30, relative to that without surfactants. The signal amplification was successfully modulated using different type of nonionic surfactants which perturb the complexation, fine-structure of the complex (i.e., donor-acceptor separation) and the resulting energy transfer process.