Fluorescence enhancement of water-soluble porphyrin-containing conjugated polymer induced by DNA and cellular imaging in living cells

A cationic conjugated polyelectrolyte (P1) containing porphyrin, fluorene and phenylene moieties was successfully synthesized by Suzuki coupling reaction. Since P1 showed two independent maximum absorption peaks at 368 and 430 nm, the fluorescence spectrum of P1 was dependent upon excitation wavelength. P1 showed strong emission upon excited at 378 nm with a maximum emission peak at 450 nm. Interestingly, the emission at 450 nm was blue-shifted to 430 nm and the approximate 95% fluorescence of P1 was quenched upon excitation at 425 nm, accompanying presence of a new emission peak at 625 nm. However, upon excited at 425 nm, 20- and 3-folds increase of emission band at 430 and 625 nm of P1 were observed in presence of DNA, respectively. This is the first report on fluorescence enhancement of porphyrin-containing conjugated polyelectrolyte induced by DNA, allowing design of an effective fluorescence turn-on DNA probe. In addition, P1 could be utilized as a fluorescent probe for cellular imaging of human adult skin fibroblast cells, where blue fluorescence was observed in the cytoplasm. The CCK-8 assay showed that the cytotoxicity of P1 was significantly low. C) 2014 Elsevier B.V. All rights reserved.