Enhanced two-photon excitation fluorescence by fluorescence resonance energy transfer using conjugated polymers

A two-photon excitation fluorescence resonance energy transfer scheme, in a system consisting of a cationic conjugated polymer. dsDNA, and a DNA intercalator, is reported. The conjugated polymer acts as two-photon excitation light-harvesting complex (see figure). The two-photon excitation fluorescence of the intercalator is found to be enhanced by a factor of over 35 upon addition of conjugated polymers. The obtained results may have profound implications in two-photon imaging and phototherapy.