SCIENCE CHINA Materials, Volume 61, Issue 11: 1475-1483(2018) https://doi.org/10.1007/s40843-018-9246-6

Synthesis of water-soluble dye-cored poly(amidoamine) dendrimers for long-term live cell imaging

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  • ReceivedFeb 9, 2018
  • AcceptedMar 6, 2018
  • PublishedMar 21, 2018


Hydrophilic dendrimers, especially poly(amidoamine) (PAMAM) dendrimers are widely applied in modifying fluorescent dyes to endow them with water solubility and biocompatibility for biologic fluorescence imaging. Common preparation strategies of fluorescent dendrimers including encapsulating dyes or attaching dyes at periphery of dendrimers might cause uncertain constituent and lower biocompatibility. Here, we have developed a series of water-soluble fluorescent dendrimers with dye as core and fan-shaped PAMAM as arms. Carboxylated perylene bisimides (PBI) dye and squarylium indocyanine (SICy) dye were conjugated with PAMAM dendrons by amidation to obtain a series of fluorescent dendrimers with enhanced water-solubility. Two PBI based dendrimers (PBI-G2.5 and PBI-G1.5) were chosen as model compounds for further optical, self-assembly and biological studies. In aqueous environment, PBI-G2.5 exhibited strong fluorescence, small size (~30 nm) and slightly positive surface charge (~2.46 mV), which are ideal for biomedical applications. In vitro assays demonstrated that PBI-G2.5 nanoparticles accumulated in the cytoplasm of HeLa cells with rapid cellular uptake. The strong fluorescence in HeLa cells remained for over 48 h. To conclude, our study provides an effective strategy for preparing water-soluble fluorescent dendrimers towards long-term live cell imaging.

Funded by

the National Natural Science Foundation of China(21774007,21574009,51521062)

and the Higher Education and High-quality and World-class Universities(PY201605)


This work was financially supported by the National Natural Science Foundation of China (21774007, 21574009 and 51521062), and the Higher Education and High-quality and World-class Universities (PY201605).

Interest statement

The authors declare no conflict of interest.

Contributions statement

Yin M and Su Z initiated and guided the work. All authors contributed to the discussion and preparation of the manuscript. The final version of the manuscript was approved by all authors.

Author information

Yang Cai received his Bachelor’s degree from Beijing University of Chemical Technology in 2015. He is now a PhD candidate under the supervision of Prof. Meizhen Yin. His research interest focuses on the synthesis and bio-application of fluorescent dyes.

Meizhen Yin got her PhD in Organic Chemistry from Dresden University of Technology, Germany in 2004. Afterwards, she worked as a postdoctor in Prof. Klaus Müllen group in Max Planck Institute for Polymer Research Mainz, Germany. Since 2009, she is a professor at Beijing University of Chemical Technology. Currently, she focuses on the design and synthesis of functional fluorescent macromolecules, multifunctional organic/inorganic nanoparticles and their biological applications.


Supplementary information

Experimental details and supporting data are available in the online version of the paper


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  • Figure 1

    1H NMR spectra of Boc-G2.5 (blue), PBI-G2.5 (red) and SICy-G2.5 (green).

  • Scheme 1

    Schematic illustration of the synthesis, self-assembly and live cell imaging of fluorescent dendrimers.

  • Scheme 2

    Synthesis route of (a) fan-shaped PAMAM dendrons and (b) fluorescent dendrimers (PBI-G0.5, PBI-G1.5, PBI-G2.5).

  • Figure 2

    (a) The photographs of aqueous PBI-G2.5 solution under natural (left) and UV light (right). (b) Absorption (dark line) and fluorescent intensity (blue line, excited at 495 nm, slit 1.5 nm) of PBI-G2.5 (0.5 μmol L−1). Concentration-dependent (c) absorption and (d) fluorescence spectra of PBI-G2.5 in water (excited at 495 nm, slit 1.5 nm).

  • Figure 3

    (a) Schematic self-assembly of amphiphilic dendrimer in water. (b) SEM micrographs of PBI-G2.5 nanoparticles (10 μmol L−1). Scale bar is 100 nm. (c) DLS data of PBI-G2.5 in deionized water (10 μmol L−1). (d) Zeta potential of PBI-G2.5 in deionized water (10 μmol L−1).

  • Figure 4

    Bright field images of (a) PBI-G1.5, (d) PBI-G2.5; fluorescence images of (b) PBI-G1.5, (e) PBI-G2.5 on the red channel and the overlay images of (c) PBI-G1.5, (f) PBI-G2.5 of HeLa cells incubated with PBI-G1.5 and PBI-G2.5 (5 μmol L−1) after 2 h. Scale bar is 100 μm.

  • Figure 5

    Dynamic fluorescence intensity of PBI dendrimers incubated with HeLa cells at different time points (Ex = 495 nm, Em = 547 nm).

  • Figure 6

    Cell viability of Hela cells incubated with different concentrations (1, 5, 10, 25 μmol L−1) of various generations of PBI (PBI-G0.5, PBI-G1.5, PBI-G2.5).

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