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Hybrid fluorescent nanoparticles fabricated from pyridine-functionalized polyfluorene-based conjugated polymer as reversible pH probes over a broad range of acidity-alkalinity

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Abstract

Conjugated polymer nanoparticles (CPNs) were developed based on a polyfluorene-based conjugated polymer with thiophene units carrying pyridyl moieties incorporated in the backbone of polymer chains (PFPyT). Hybrid CPNs fabricated from PFPyT and an amphiphilic polymer (NP1) displayed pH-sensitive fluorescence emission features in the range from pH 4.8 to 13, which makes them an attractive nanomaterial for wide range optical sensing of pH values. The fluorescence of hybrid CPNs based on chemically close polyfluorene derivatives without pyridyl moieties (NP3), in contrast, remains virtually unperturbed by pH values in the same range. The fluorescence emission features of NP1 underwent fully reversible changes upon alternating acidification/basification of aqueous dispersions of the CPNs and also displayed excellent repeatability. The observed pH sensing properties of NP1 are attributed to protonation/deprotonation of the nitrogen atoms of the pyridine moieties. This, in turn, leads to the redistribution of electron density of pyridine moieties and their participation in the π-conjugation within the polymer main chains. The optically transparent amphiphilic polymers also exerted significant influence on the pH sensing features of the CPNs, likely by acting as proton sponge and/or acid chaperone.

pH-sensitive fluorescent nanoparticles were fabricated from pyridine-functionalized conjugated polymer; protonation/deprotonation of the nitrogen atoms of pyridine moieties upon pH changes, which leads to the redistribution of electron density of pyridine moieties and their participation in the π-conjugation with polymer chains, were confirmed.

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Acknowledgments

This work was supported by the National Natural Science Foundation of China (grant no. 21173262, 21373218) and the “Hundred-Talent Program” of CAS to Z. Tian.

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Authors and Affiliations

  1. School of Chemistry & Chemical Engineering, University of Chinese Academy of Sciences (UCAS), Beijing, 100049, China

    Haijun Cui, Ying Chen & Zhiyuan Tian

  2. Laboratory for Nanomaterials, National Center for Nanoscience and Technology, Beijing, 100190, China

    Haijun Cui, Ying Chen, Lianshan Li & Zhiyong Tang

  3. Beijing National Laboratory for Molecular Science (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory for Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China

    Yishi Wu & Hongbing Fu

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  1. Haijun Cui
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  2. Ying Chen
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  4. Yishi Wu
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  5. Zhiyong Tang
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Correspondence to Lianshan Li, Yishi Wu or Zhiyuan Tian.

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Cui, H., Chen, Y., Li, L. et al. Hybrid fluorescent nanoparticles fabricated from pyridine-functionalized polyfluorene-based conjugated polymer as reversible pH probes over a broad range of acidity-alkalinity. Microchim Acta 181, 1529–1539 (2014). https://doi.org/10.1007/s00604-014-1219-4

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  • DOI: https://doi.org/10.1007/s00604-014-1219-4

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