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

Abstract

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.

Molecular imaging of biological systems with a clickable dye in the broad 800- to 1,700-nm near-infrared window

“…QY in toluene (34); however, its analog with ionic groups showed little fluorescence in aqueous solution (QY <0.1%) (33). The molecular fluorophore IR-FTP with TEG-thiophene substituted by thiophene also exhibited a fluorescence QY of only 0.020%, highlighting the novelty of the TEG-thiophene bridge in IR-FGP (SI Appendix, Fig.…”

Near‐Infrared‐II Molecular Dyes for Cancer Imaging and Surgery

“…Copyright 2016, The Royal Society of Chemistry. e) Schematic illustration of the design of bright molecular fluorophores with either single or double‐donor optimization produced several key fluorophores . Reproduced with permission .…”

Rational design of fluorescent probe for Hg2+ by changing the chemical bond type

“…And the photoluminescence spectra for all the dyes are broad and structureless, which consistent with ICT characteristics for such kind of dyes. 25 Furthermore, the emission spectra of DFABT and WDFABT exhibited an obvious blue-shi with green color compared with that of DFBT and WDFBT, which probably due to the inhomogeneity in the conjugation path caused by the triple bond. 32 The relative uorescent quantum yields (f) are 0.69, 0.58, 0.71 and 0.09 for DFBT, WDFBT, DFABT Scheme 1 Chemical structure of DFBT, DFABT, WDFBT and WDFABT.…”

“…Benzo [2,1,3]thiadiazole (BT) moiety is a kind of well-known metal ions receptor uorophore with widespread application as uorescent probe due to its valuable characteristics, such as simple, stable and malleable chemical structure, large Stokes shi in the visible spectral region, high uorescence quantum yields, and better mercury ion coordination selectivity. [22][23][24][25] However, to the best of our knowledge, the reported uorescent probes based on BT for real-time detection of Hg 2+ in pure aqueous solution are still relatively rare, especially for the reversible one, which is important in vitro and in vivo application. 21 Thus, the design and development of effective uorescent probe of Hg 2+ with excellent water-solubility, high sensitivity and selectivity, especially with reversibility based on BT moiety is of great necessary.…”