Enhanced Two-Photon Excitation Fluorescence by Fluorescence Resonance Energy Transfer Using Conjugated Polymers

摘要

Conjugated polymers are known to provide the advantage of a collective optical response. They can function as light harvesting materials and exhibit enhanced quenching efficiency by electron transfer or optical amplification via Forster resonance energy transfer (FRET). Because of these exceptional properties, conjugated polymers are useful in the detection of biological and chemical target molecules with high sensitivity.Conjugated polymers also have large two-photon absorption cross sections, compared with their small-molecule counterparts. Materials with large two-photon cross sections have potential applications in data storage, phototherapy, 3D imaging, and microfabrication. Here, we report enhanced two-photon excitation fluorescence by FRET from a cationic conjugated polymer to a DNA intercalator. The fluorescence intensity of the DNA intercalator, by two-photon excitation FRET (TPE-FRET), was found to be enhanced by a factor of over 35 compared to the value obtained when the intercalator was directly excited by two-photon absorption.