Synthesis and Characterization of Water-Soluble Conjugated Oligoelectrolytes for Near-Infrared Fluorescence Biological Imaging

Shin Jae Woo, Sungmin Park, Ji Eun Jeong, Yoochan Hong, Minhee Ku, Bo Yun Kim, Il Ho Jang, Soon Chul Heo, Taejun Wang, Ki Hean Kim, Jaemoon Yang, Jae Ho Kim, Han Young Woo

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Near-infrared (NIR) fluorophores attract increasing attention as a molecular marker (or probe) for in vivo and in vitro biological fluorescence imaging. Three types of new NIR fluorescent conjugated oligoelectrolytes (COEs: Q-FlTBTTFl, Q-FlBBTFl, and Q-FlTBBTTFl) are synthesized with quaternized ammonium ionic groups in their side-chains for water solubility. The emission wavelength is modulated in the range 600-1300 nm, by adjusting the intramolecular charge transfer in the molecular backbone based on the electron-rich fluorene (and/or thiophene) and electron-deficient benzo[2,1,3]thiadiazole (or benzo[1,2-c:4,5-c′]bis[1,2,5]thiadiazole) moieties. The COEs show a remarkably larger Stokes shift (147-276 nm) compared to commercial rhodamine and cyanine dyes in water, avoiding self-quenching and interference from the excitation backscattered light. The photoluminescence (PL) quantum efficiency is improved substantially by up to 27.8% in water by fabricating a vesicular complex, COE/v, with a block ionomer, poly[(ethylene oxide)-block-(sodium 2-acrylamido-2-methyl-1-propanesulfonate)]. In vitro cellular uptake images with the COEs are obtained with good biocompatibility by confocal single-photon and two-photon microscopy. The ex vivo and in vivo images of a mouse xenograft model treated with the Q-FlBBTFl/v exhibit a substantially stronger fluorescence signal at the tumor site than at the other organs, highlighting the potential of the COE/v as an NIR fluorescent imaging agent for the diagnosis of cancer.

Original languageEnglish
Pages (from-to)15937-15947
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number25
Publication statusPublished - 2016 Jun 29

Bibliographical note

Funding Information:
We are grateful for financial support from the National Research Foundation ( N R F ) of Korea (2015R1A2A1A15055605, 2015R1D1A1A09056905, and 20100020209).

Publisher Copyright:
© 2016 American Chemical Society.


  • Stokes shift
  • bioimaging
  • conjugated oligoelectrolytes
  • near-infrared fluorophores
  • vesicle

ASJC Scopus subject areas

  • General Materials Science


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