Eccentric Loading of Fluorogen with Aggregation-Induced Emission in PLGA Matrix Increases Nanoparticle Fluorescence Quantum Yield for Targeted Cellular Imaging

Authors

  • Junlong Geng,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Fax: (+65) 6779-1936, E-mail: cheliub@nus.edu.sg
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  • Kai Li,

    1. Institute of Materials Research Engineering, 3 Research Link, 117602, Singapore
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  • Wei Qin,

    1. Department of Chemistry, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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  • Lin Ma,

    1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
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  • Gagik G. Gurzadyan,

    1. Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore
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  • Ben Zhong Tang,

    1. Institute of Materials Research Engineering, 3 Research Link, 117602, Singapore
    2. Department of Chemistry, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
    3. SCUT-HKUST Joint Research Laboratory, Guangdong Innovative Research Team, State Key Laboratory of Luminescent, Materials and Devices, South China University of Technology, Guangzhou, China, 510640
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  • Bin Liu

    Corresponding author
    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Fax: (+65) 6779-1936, E-mail: cheliub@nus.edu.sg
    2. Institute of Materials Research Engineering, 3 Research Link, 117602, Singapore
    • Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Fax: (+65) 6779-1936, E-mail: cheliub@nus.edu.sg;.
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Abstract

A simple strategy is developed to prepare eccentrically or homogeneously loaded nanoparticles (NPs) using poly (DL-lactide-co-glycolide) (PLGA) as the encapsulation matrix in the presence of different amounts of polyvinyl alcohol (PVA) as the emulsifier. Using 2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl)-phenyl)amino)-phenyl)-fumaronitrile (TPETPAFN), a fluorogen with aggregation-induced emission (AIE) characteristics, as an example, the eccentrically loaded PLGA NPs show increased fluorescence quantum yields (QYs) as compared to the homogeneously loaded ones. Field emission transmission electron microscopy and fluorescence lifetime measurements reveal that the higher QY of the eccentrically loaded NPs is due to the more compact aggregation of AIE fluorogens that restricts intramolecular rotations of phenyl rings, which is able to more effectively block the non-radiative decay pathways. The eccentrically loaded NPs show far red/near infrared emission with a high fluorescence QY of 34% in aqueous media. In addition, by using poly([lactide-co-glycolide]-b-folate [ethylene glycol]) (PLGA-PEG-folate) as the co-encapsulation matrix, the obtained NPs are born with surface folic acid groups, which are successfully applied for targeted cellular imaging with good photostability and low cytotoxicity. Moreover, the developed strategy is also demonstrated for inorganic-component eccentrically or homogeneously loaded PLGA NPs, which facilitates the synthesis of polymer NPs with controlled internal architectures.

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