Specific and sensitive imaging of basal cysteine over homocysteine in living cells

Development of a NIR fluorescent probe for highly selective and sensitive detection of cysteine in living cells and in vivo

Cysteine (Cys) plays important physiological roles in the human body, and abnormal Cys concentrations can cause a variety of diseases. Thus, detecting Cys with high selectivity and sensitivity in vivo is important. Near-infrared (NIR) fluorescent probes are widely employed in biological detection because of their excellent optical properties such as minimal damage to biological samples, low background interference and high signal-to-noise ratio. However, few NIR fluorescent probes that can detect Cys over homocysteine (Hcy) and glutathione (GSH) have been reported because of their similar reactivity and structure. In this work, a highly water-soluble NIR probe (CYNA) for detecting Cys whose structure is similar to that of indocyanine green and is based on cyanine skeleton was synthesized and via aromatic nucleophilic substitution-rearrangement (SNAr-rearrangement) to specific recognize the cysteine. The probe showed high selectivity toward Cys and superior biosecurity, excellent biocompatibility and prolonged dynamic imaging. It also has long fluorescence emission wavelength (820 nm), low detection limit (14 nM) and was successfully applied for visualizing Cys in living cells and mice, which has great promise for applications in noninvasive vivo biological imaging and detection.

A Pyrene-Based Fluorescent Probe for Specific Detection of Cysteine and its Application in Living Cell

Cysteine (Cys) is an essential amino acid in organism, which is transformed from methionine in vivo and participates in protein synthesis and cell redox process. Therefore, the detection of Cys is of great significance. In this work, a novel fluorescent probe, (E)-3-(2-chloroquinolin-3-yl)-1-(pyren-3-yl) prop-2-en-1-one (PAQ) was designed and synthesized to specifically detect Cys. The response mechanism of the reaction between PAQ and Cys was due to the addition reaction of Cys to α,β-unsaturated ketone of PAQ. Interestingly, the addition of Cys induced significant fluorescence intensity enhancement at 462 nm. PAQ exhibited favorable sensing properties towards Cys such as the low limit of detection (0.27 μM) and fast response speed (2 min). In addition, PAQ displayed high selectivity and anti-interference ability toward Cys among various analytes. Notably, PAQ has been successfully used to image exogenous and endogenous Cys in HeLa cells.

Near-infrared fluorogenic receptor for selective detection of cysteine in blood serum and living cells

A novel near-infrared fluorescent probe, namely propane-2,2-diylbis(2-((E)-2-(benzo[d]thiazol-2-yl)-2-cyanovinyl)-4,1-phenylene) diacrylate (BTA), was synthesized for selective detection of cysteine over other biologically significant amino acids. Upon addition of cysteine, the probe BTA displays a dramatic increase in fluorescence intensity at 715 nm along with a fast response time (4 min). The limit of detection (LOD) was calculated as 0.12 μM. In addition, the synthesized probe BTA was effectively utilized for the recognition of cysteine in blood serum and living cells.

A novel 2,5-bis(benzo[d]thiazol-2-yl)phenol scaffold-based ratiometric fluorescent probe for sensing cysteine in aqueous solution and serum

An efficient and novel 2,5-bis(benzo[d]thiazol-2-yl)phenol scaffold-based ratiometric fluorescent probe BTP-Cys for the sensing of cysteine has been developed. The probe BTP-Cys with acrylates moiety, as recognition site, has been successfully constructed on account of the excited state intramolecular proton transfer (ESIPT) mechanism. Upon the treatment with Cys (0-250 μM), this probe BTP-Cys exhibits a dramatic fluorescent intensity ratios enhancement (from 0.03 to 18.3) and a large emission shift (113 nm). The detection limit of this probe is as low as 3.8 × 10^-7 M. Importantly, the concentration and time dependent of Cys in bovine serum albumin (BSA) has also been measured, indicating that BTP-Cys could be a biocompatible and rapid probe for Cys in vitro.

A near-infrared fluorescent probe for the discrimination of cysteine in pure aqueous solution and imaging of cysteine in hepatocellular carcinoma cells with facile cell-compatible ability

A NIR fluorescence sensor for selectively detecting cysteine in aqueous solution with fast response and long emission wavelength was synthesized.