A novel near-infrared fluorescent probe for detection of hypobromous acid and its bioimaging applications

Author links open overlay panelWangboQu^ab XiaoyuZhang^b YingyingMa^b FabiaoYu（于法标）^a* HengLiu（刘恒）^ab*

• ^aInstitute of Functional Materials and Molecular Imaging, College of Clinical Medicine, Key Laboratory of Hainan Trauma and Disaster Rescue, College of Emergency and Trauma, Hainan Medical University, Haikou 571199, PR China

• ^bHubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules & College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, PR China

Received 4 May 2019, Revised 17 May 2019, Accepted 5 June 2019, Available online 6 June 2019.

https://doi.org/10.1016/j.saa.2019.117240

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Available online 6 June 2019, 117240

Abstract
Hypobromous acid (HOBr) is an important reactive oxygen species and has been
recently found to be associated with a variety of diseases. However, owing to a lack of
effective analytical tools, there is still limited understanding of its roles in living
systems. Here, we present a new type of near-infrared fluorescent probe DCSN for
HOBr detection. The designed probe exhibits high sensitivity with a low detection
limit, excellent selectivity over other interfering species and low cytotoxicity. More
interestingly, the fluorescence response behavior of the probe was different from the
previous literatures due to the intramolecular charge transfer process. Moreover, we
have successfully monitored HOBr in living cells by utilizing DCSN. This probe has
potential to be used as a promising tool for better understanding the physiological
functions of HOBr.

 Scheme 1. Synthesis of the target fluorescent probe DCSN (a) and the reaction
mechanism of DCSN with HOBr.

Fig. 1. (a) UV-vis absorption spectra of DCSN (10 μM) before and after addition of
HOBr (50 μM). (b) Titration graph of DCSN (10 μM) upon gradual addition of
various amounts (0-40 μM). Inset (b): photographs of DCSN without or with HOBr
under UV irradiation. (c) Fluorescence intensities at 655 nm of DCSN (10 μM) versus
HOBr concentrations (0-35 μM). (d) Time dependent fluorescence measures of DCSN
(10 μM) before and after treatment with of HOBr (50 μM).

Fig. 2. (a) pH effect on the fluorescence intensities at 655 nm of DCSN (10 μM) in
the absence and presence of HOBr (50 μM). (b) Selective fluorescence response of
DCSN toward common physiological ROS, RNS and RSS analytes. 50 μM for HOBr,
500 μM for H2O2、.OH、 1O2、NO2-、NO3-, 200 μM for HClO, 100 μM for Na2S, 1 mM
for GSH and 300 μM for Cys、Hcy.

Fig. 3. Bright field (top row), red channel (second row), merged (third row) images of
MCF-7 cells incubated with (10 μM) for 30 min, and then further treated with (a)
nothing, (b) HOBr (100 μM), (c) NaBr (100 μM), (d) N-acetylcysteine (20 μM)/NaBr
(100 μM) and (e) H2O2 (100 μM )/NaBr (100 μM ) for 30 min, respectively. (f)
Fluorescence intensity of cells in panels (f) to (j). λex = 488 nm, λem = 600-700 nm,
scale bar = 20 μm.