A Micellar Complex of a Conjugated Polyelectrolyte for Efficient FRET to Dye-Labeled DNA

A polymer-surfactant micellar complex has been studied as a fluorescence resonance energy transfer (FRET) donor to fluorescein-labeled DNA (ssDNA-Fl). In water, the molar absorptivity and fluorescence quantum efficiency of cationic poly(fluorene-co-phenylene) (c-PFP) are substantially increased in the presence of non-ionic surfactants. A TEM microscopic study shows the formation of a nanowire micellar complex of c-PFP and the surfactants. About a 400% enhancement of the FRET signal is measured in c-PFP/ssDNA-Fl with Brij 30, relative to that without surfactants. The signal amplification is successfully modulated using different types of non-ionic surfactants which perturb the complexation, fine-structure of the complex (i.e., donor-acceptor separation), and the resulting energy transfer process.