Conjugated polymers are novel low-dimensional materials with many interesting optical and electronic properties. They display optical amplification via fluorescence resonance energy transfer (FRET), which has been utilized to develop biosensors with enhanced detection efficiency. Conjugated polymers also have large two-photon absorption cross sections compared to the small molecule counterpart. We have demonstrated that conjugated polymers can act as two-photon light harvesting complexes to enhance the two-photon emission of dyes and photosensitizers by up to 1000 times. Using this strategy, we have developed a two-photon sensor scheme for detection of Mercury ions with detection limit of as low as ~6 nm. We further extended the strategy to develop dye doped conjugated polymer nanoparticles for two-photon imaging and photosensitizer doped conjugated polymer nanoparticles for two-photon photodynamic therapy. The photosensitizer doped conjugated polymer nanoparticles showed significantly enhanced two-photon excitation singlet oxygen generation efficiency and two-photon photodynamic therapy activity in cancer cells. These nanoparticles display features required for ideal photosensitizers, such as low cytotoxicity in the dark and efficient two-photon photodynamic activity under laser radiation. These novel nanophotosensitizers allow simultaneous two-photon fluorescence imaging and two-photon photodynamic treatment. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/33197_toc.jpg' alt='' /> Scheme 1. Two-photon excitation energy transfer from conjugated polymers to enhance two-photon optical properties of dyes/photosensitizers for two-photon imaging and photodynamic therapy.Reference 1. Tian, N.; Xu, Q.-H., Adv. Mater., 2007 , 19(15), 1988.2. Ren, X. S.; Xu, Q.-H. Langmuir, 2009 , 25(1), 29.3. Wu, C.; Xu, Q.-H. Macromol. Rapid Commun., 2009 , 30, 504.4. Shen, X.Q.;, He, F.; Wu, J.H., Xu, G.Q.; Yao, S.Q., Xu, Q.-H. Langmuir, 2011 , 27 (5), 1739.5. He, F.; Ren, X.S.; Shen, X. Q.; Xu, Q.-H. Macromolecules, 2011 , 44, 5373.6. Shen, X.Q.; Li, L.; Wu, H., Yao, S. Q.; Xu, Q.-H. Nanoscale, 2011, 3, 5140.

Conjugated polymers as two-photon absorption materials for biological applications

247th National Meeting (2014)

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