Rational design of a ratiometric fluorescent probe for imaging lysosomal nitroreductase activity

Wenjun Bai; Yixuan Li; Li Zhao; Ruxin Li; Jiahou Geng; Yang Lu; Yufen Zhao; Jinhui Wang

doi:10.1016/j.saa.2023.123032

Rational design of a ratiometric fluorescent probe for imaging lysosomal nitroreductase activity

Spectrochim Acta A Mol Biomol Spectrosc. 2023 Dec 5:302:123032. doi: 10.1016/j.saa.2023.123032. Epub 2023 Jun 20.

Authors

Wenjun Bai¹, Yixuan Li², Li Zhao¹, Ruxin Li¹, Jiahou Geng¹, Yang Lu³, Yufen Zhao⁴, Jinhui Wang⁵

Affiliations

¹ Institute of Drug Discovery Technology, Ningbo University, Ningbo, China.
² Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo, China.
³ Institute of Drug Discovery Technology, Ningbo University, Ningbo, China. Electronic address: luyang@nbu.edu.cn.
⁴ Institute of Drug Discovery Technology, Ningbo University, Ningbo, China; Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo, China.
⁵ Institute of Drug Discovery Technology, Ningbo University, Ningbo, China; Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo, China. Electronic address: wangjinhui@nbu.edu.cn.

PMID: 37356386
DOI: 10.1016/j.saa.2023.123032

Abstract

Overexpressed nitroreductase (NTR) is often utilized to evaluate the hypoxic degree in tumor tissues, thus it is of great importance to develop high selective and efficient optical method to detect NTR. The dynamic fusion and function of lysosome promoted us to explore the possible appearance of NTR inside this organelle and to probe its behavior in a cellular context. In this work, a ratiometric fluorescent probe based on an extended π-π conjugation of a triphenylamine unit was designed for NTR detection and lysosomes imaging. The dual-emission mechanism of the probe in the presence of catalytic NTR was confirmed by theoretical study. The structure-function relationship between probe and NTR was revealed by docking calculations, suggesting a suitable structural and spatial match of them. The photophysical studies showed the probe had high selectivity, rapid response and a wide pH range towards NTR. MTT assay indicated the probe had low cytotoxicity in both normal (HUVEC) and tumor (MCF-7) cells. Furthermore, the inverse fluorescent imaging results confirmed the probe was NTR-active and exhibited time- and concentration-dependent fluorescence signals. In addition, the relatively high Pearson's correlation coefficient (0.99 in HepG2 and 0.97 in MCF-7 cells, compared to Lyso-Tracker Red) demonstrated the probe had excellent lysosomes colocalization. This study illustrates a ratiometric detection of NTR agent for lysosomes fluorescent imaging, which may provide a novel insight in molecular design.

Keywords: Lysosome imaging; Nitroreductase responsive; Ratiometric; Triphenylamine.

MeSH terms

Cell Line, Tumor
Fluorescent Dyes* / chemistry
Humans
Lysosomes*
Microscopy, Fluorescence
Nitroreductases / chemistry
Optical Imaging / methods

Substances

Fluorescent Dyes
Nitroreductases