A near-infrared excitation/emission fluorescent probe for imaging of endogenous cysteine in living cells and zebrafish

Abstract

The fluorescence imaging technique provides an essential tool for studying biological systems. However, due to the interference of autofluorescence of biological tissues, the application of short-wavelength fluorescent probes in biological imaging was limited. The near-infrared (NIR) excitation/emission fluorescent probe possesses unique advantages in optical imaging in vivo, including less light scattering, minimal photo-damage to biological samples, deep tissue penetration, and weak autofluorescence interference from complicated biological systems. In this work, a convenient fluorophore (E)-2-[2-(6-hydroxy-2,3dihydro-1H-xanthen-4-yl)vinyl]-3-methylbenzo[d]thiazol-3-ium iodide (DXM-OH) with NIR excitation and emission was rationally designed and developed. What's more, DXM-OH was applied to construct an "OFF-ON" fluorescent probe (E)-2-{2-[6-(acryloyloxy)-2,3-dihydro-1H-xanthen-4-yl]vinyl}-3-methylbenzo[d]thiazol-3-ium iodide (DXM) for sensitive and selective detection of cysteine (Cys). The experimental results showed that DXM had the advantages of good cell permeability, low toxicity, and excellent optical properties (NIR excitation/emission) and it was successfully applied to image Cys of living cells and zebrafish.

Design, synthesis, and biological application of A–D–A-type boranil fluorescent dyes

“…[9][10][11] In contrast, difluoroboron complexes like boranil dyes, with their asymmetric structure, exhibit significantly larger Stokes shifts. [12][13][14] Yet, conventional boranil dyes emit at short wavelengths, making them prone to autofluorescence interference and limiting tissue penetration. Generally, the optical wavelengths of donor-acceptor (D-A) complexes can be redshifted by strengthening the electron-donating/electronwithdrawing ability of electron donors and/or acceptors, and expanding the π conjugation system.…”

A ratiometric fluorescent probe based on two-isophorone fluorophore for detecting cysteine

“…Compared with common analysis methods such as fluorescent spectroscopy, potentiometry, and high performance liquid chromatography (HPLC), 9,[12][13][14][15][16][17][18] which are cumbersome and less used for the intracellular detection of biological thiols, fluorescent probes have attracted increasing attention in this field because of their simple operation, high resolution, high sensitivity, real-time detection, penetrability and noninvasiveness. [19][20][21][22][23][24][25][26] At present, more and more small molecule fluorescent probes and nanosensors have been designed, synthesized, and extensively used in the detection of biological thiols. [27][28][29][30][31][32][33][34] So far, numerous fluorescent probes for Cys detection based on various reaction mechanisms have been synthesized and reported, which are mainly based on Michael addition reactions, cleavage of disulfide bonds, substitution reactions, disulfide exchange, etc., 35 and nanosensors are mainly based on the colorimetric reaction of the aggregation of gold nanoparticles, the aggregation of graphene quantum dots and the fluorescence reaction, etc.…”

The Two‐Steps Reaction Fluorescent Probe for the Selective Detection of Cysteine and Its Applications**

“…In 2009, Peng's group utilized the aldehyde group as the reaction site for the first time to detect Cys based on the formation and hydrolysis of thiazolidine derivatives, with turn‐on fluorescence response [11] . Based on the specific nucleophilic addition and intramolecular cyclization reaction between Cys and propenyl, several probes have been reported for the specific detection of Cys [12–20] . These probes for detection of Cys are turn ‘off‐on’ fluorescence with one‐step reaction, and the changes of fluorescence color are relatively simple and simplified.…”