Proc. SPIE. 9523, International Conference on Nano-Bio Sensing, Imaging, and Spectroscopy 2015
KEYWORDS: Energy efficiency, Polymers, Luminescence, Molecules, Energy transfer, Resonance energy transfer, Picosecond phenomena, Time resolved spectroscopy, Fluorescence resonance energy transfer, Absorption
We have investigated that organic solvent (DMSO, dimethyl sulfoxide) modifies energy transfer efficiency between conjugated polymers (donors) and fluorescein-labeled single stranded DNAs (acceptors). In a mixture of buffer and organic solvent, fluorescence of the acceptors is significantly enhanced compared to that of pure water solution. This result can be attributed to change of the donor-acceptor environment such as decreased hydrophobicity of polymers, screening effect of organic solvent molecules, resulting in an enhanced energy transfer efficiency. Time-resolved fluorescence decay of the donors and the acceptors was modelled by considering the competition between the energy harvesting Foerster resonance energy transfer and the energy-wasting quenching. This enables to quantity that the Foerster distance (R<sub>0</sub> = 43.3 Å) and resonance energy transfer efficiency (E<sub>FRET</sub> = 58.7 %) of pure buffer solution become R<sub>0</sub> = 38.6 Å and E<sub>FRET</sub> = 48.0 % when 80% DMSO/buffer mixture is added.