Imaging Of Cysteine Research Articles

Near-Infrared Fluorescent Probe for the Detection of Cysteine.

Hemicyanine dyes are an ideal structure for building near-infrared fluorescent probes due to their excellent emission wavelength properties and biocompatibility in biological imaging field. Developing a near-infrared fluorescent probe capable of detecting cysteine (Cys) was the aim of this study. A novel developed fluorescent probe P showed high selectivity and sensitivity to Cys in the presence of various analytes. The detection limit of P was found to be 0.329 μM. The MTT assay showed that the probe was essentially non-cytotoxic. Furthermore, the probe was successfully used as cysteine imaging in living cells and mice.

An extra-large Stokes shift near-infrared fluorescent probe for specific detection and imaging of cysteine

Cysteine (Cys) plays a crucial role in numerous physiological and pathological processes. Therefore, it is imperative to design a highly selective and sensitive near-infrared (NIR) fluorescent probe to monitor Cys. In this study, we have developed a novel NIR fluorescent probe XA based on Xanthene hybrid tetrahydro-acridine salt dye for specifically tracking of Cys, where a chlorine-substituted tetrahydro-acridine acts as a high Cys-reactive site and water-soluble group. Probe XA exhibits a remarkable "turn-on" NIR emission (830 nm) with an extra-large Stokes shift (305 nm) for monitoring Cys. It also has a high selectivity, rapid response time (6 min) and high sensitivity (LOD as 0.5 μM). We fully characterized and discussed the sensing mechanism of XA toward Cys using HPLC and MS spectrums, as well as quantum theory calculations. Furthermore, the excellent properties of NIR fluorescent detection allow this novel probe to successfully monitor fluctuations of exogenous and endogenous Cys concentration levels in living cells and in vivo.

Rational design of a novel acryl-modified CQDs fluorescent probe for highly selective detection and imaging of cysteine in vitro and in vivo.

Anovel fluorescent nanoprobe CQDs-O-Acryl has been designed and synthesized to directly and accurately identify Cys over other biothiols in PBS (10mM, pH 7.4) buffer. The carbon quantum dots (CQDs-OH) (λex/em maxima = 495/525nm) were fabricated by a solvothermal method using resorcinol as the carbon source. The CQDs-O-Acryl was achieved through covalently grafting the acryloyl group on the surface of carbon quantum dots by nuclear reaction based on static quenching. The structure and morphology of CQDs-OH and CQDs-O-Acryl have been characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV-vis absorption spectroscopy. Upon the addition of Cys, the ester bond of CQDs-O-Acryl has been broken, and the free CQDs were released by conjugated addition and cyclization reactions successively, emitting strong green fluorescence at 525nm (λex = 495nm). Under the optimized conditions, CQDs-O-Acryl exhibited good sensing of Cys within the range 0.095-16μM (the LOD of 0.095μM). Due to the high sensitivity, reliability, fast fluorescence response (10min), and low toxicity of CQDs-O-Acryl, it was successfully applied to fluorescence imaging of Cys in A549 cells and zebrafish.

A novel ratiometric fluorescent probe for the detection and imaging of cysteine in living cells

Cysteine is an essential amino acid for humans and can be generated from the conversion of methionine or the interconversions with cystine. The detection of cysteine in the living system is of great importance for the diagnosis of related diseases. Based on the classical cysteine response mechanism, the sulfhydryl group of cysteine undergoes Michael addition with the acrylate to rapidly respond to form a seven-membered ring that specifically recognizes cysteine. In the present work, we designed a novel ratiometric fluorescent probe N-1, which contained the benzo[cd]indol fluorophore and the response group acrylate. As the concentration of cysteine increased, the fluorescence of I485 was significantly enhanced while the fluorescence intensity at 635 nm was weakened. Moreover, probe N-1 showed excellent sensitivity and selectivity to Cys with the calculated LOD of 4.0 × 10-9 M. Probe N-1 was successfully used for imaging cysteine in the living Hela cells with low cytotoxicity, indicating that this ratiometric fluorescent probe would be a novel and useful tool to monitor cysteine in the physiological or pathological processes.

Time-dependent NIR fluorescent probe with large Stokes-shift for detecting Cys/Hcy and cell imaging

Detection and imaging of Cysteine (Cys) and Homocysteine (Hcy) in living systems have drawn extensive attention over the years due to their significant biological role. However, few fluorescence probes have been reported to distinguish Cys and Hcy in near-infrared (NIR) range. In this paper, an original NIR Cys and Hcy fluorescent probe, namely DTRN, was synthesized. DTRN was constructed by using an acryloyl ester group as a trigger and dicyanoisophorone-derived as the fluorophore unit, it was found to emit NIR fluorescence with a 718 nm emission and have large stokes shift (∼176 nm). DTRN hold excellent performances such as ultrasensitivity (LOD = 0.09 μM), high specificity and fast response (<2 min) for Cys. Distinctly, after Hcy was introduced, the emission intensity of DTRN at 718 nm must take 20 min to reach a plateau and the LOD was found to be 0.12 μM. The sensing mechanism for Cys and Hcy in C2H5OH/PBS (4/6, v/v, pH = 7.4) was studied by 1H NMR spectroscopy and HRMS. Most importantly, the ability of DTRN to detect Cys in HeLa cells had also been achieved.

ESIPT triggered swift determination of cysteine in HeLa cell line during redox imbalance

Detection of cysteine is crucial as its deviation from normal concentration leads to various diseases. In this work, benzothiazole based chemodosimeter was synthesized to discriminate cysteine rapidly in the presence of other competing interferences. The probe exhibit ESIPT governed colorimetric and fluoremetric response on addition of cysteine via conjugate addition-cyclization reaction and it is confirmed by NMR and HRMS. The probe can detect lower concentration of cysteine with limit of detection 0.07 μM in 2 min that assist the system to work well in biological systems. Hence the sensor was profitably employed in imaging of cysteine in HeLa cell line and variance in the redox state was also investigated.

A novel off-on fluorescent probe for specific detection and imaging of cysteine in live cells and in vivo

Cysteine (Cys) plays a pivotal role in many physiological and pathological processes, including detoxification and protein synthesis. The abnormal levels of Cys are linked to many diseases. In this study, a novel red-emitting off-on fluorescent probe Cys-TCF was masterly constructed for discriminative detection of Cys. After a series of experimental assessment, Cys-TCF displayed higher selectivity and sensitivity for Cys over other biothilols with a low detection limit (0.04 μmol/L). More notably, the probe was also successfully applied to image Cys in live cells and live zebrafishes with low cytotoxicity.

Cascade reaction-based trinal-site probe for sensing and imaging of cysteine and glutathione

Biothiols, such as glutathione (GSH) and cysteine (Cys), play important roles in many physiological processes, and variations in their levels are related to different diseases. Many fluorescence probes have been developed to understand the function of biothiols, but only few of such probes can detect both Cys and GSH. Herein, a new strategy for specific colorimetric and fluorescent detection of Cys and GSH by different cascade reactions was developed. By utilizing this strategy, we designed and synthesized two fluorescent probes, namely, CR1 and CR2, for detection of Cys and GSH under physiological conditions. CR1 contains a stronger electron-withdrawing substituent group and provides high selectivity and sensitivity for Cys and GSH. This probe is based on the mechanism of Cys-induced native-chemical-ligation-cyclization and GSH-induced transthioesterification–cyclization cascade reactions, with detection limits of 0.029 and 0.371 μM, respectively. CR1 can be successfully applied for imaging Cys and GSH in living cells with low cell toxicity.

Cover Feature: Iridium(III) Complex‐Based Activatable Probe for Phosphorescent/Time‐Gated Luminescent Sensing and Imaging of Cysteine in Mitochondria of Live Cells and Animals (Chem. Eur. J. 6/2019)

Cover Feature: Iridium(III) Complex‐Based Activatable Probe for Phosphorescent/Time‐Gated Luminescent Sensing and Imaging of Cysteine in Mitochondria of Live Cells and Animals (Chem. Eur. J. 6/2019)

Iridium(III) Complex-Based Activatable Probe for Phosphorescent/Time-Gated Luminescent Sensing and Imaging of Cysteine in Mitochondria of Live Cells and Animals.

This study reports an activatable iridium(III) complex probe for phosphorescence/time-gated luminescence detection of cysteine (Cys) in vitro and in vivo. The probe, [Ir(ppy)2 (NTY-bpy)](PF6 ) [ppy: 2-phenylpyridine; NTY-bpy: 4-methyl-4'-(2-nitrovinyl)-2,2'-bipyridine], is developed by incorporating a strong electron-withdrawing group, nitroolefin, into a bipyridine ligand of the IrIII complex. The luminescence of the probe is quenched owing to the intramolecular charge transfer (ICT) process, but switched on by a specific recognition reaction between the probe and Cys. [Ir(ppy)2 (NTY-bpy)](PF6 ) shows high sensitivity and selectivity for Cys detection and good biocompatibility. The long-lived emission of [Ir(ppy)2 (NTY-bpy)](PF6 ) allows time-gated luminescence analysis of Cys in cells and human sera. These properties make it convenient for the phosphorescence and time-gated luminescence imaging and flow cytometry analysis of Cys in live samples. The Cys images in cancer cells and inflamed macrophage cells reveal that [Ir(ppy)2 (NTY-bpy)](PF6 ) is distributed in mitochondria after cellular internalization. Visualizations and flow cytometry analysis of mitochondrial Cys levels and Cys-mediated redox activities of live cells are achieved. By using [Ir(ppy)2 (NTY-bpy)](PF6 ) as a probe, in vivo sensing and imaging of Cys in D. magna, zebrafish, and mice are then demonstrated.

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.

Amino Nitrogen Quantum Dots-Based Nanoprobe for Fluorescence Detection and Imaging of Cysteine in Biological Samples.

Fluorescent amino nitrogen quantum dots (aN-dots) were synthesized by microwave-assisted method using 2-azidoimidazole and aqueous ammonia. The aN-dots have a nitrogen component up to 40%, which exhibit high fluorescence quantum yield, good photostability, and excellent biocompatibility. We further explored the use of the aN-dots combined with AuNPs as a nanoprobe for detecting fluorescently and imaging of cysteine (Cys) in complex biological samples. In this sensing system, the fluorescence of aN-dots was quenched significantly by gold nanoparticles (AuNPs), while the addition of Cys can lead to the fluorescence signal recovery. Furthermore, we have demonstrated that this strategy can offer a rapid and selective detection of Cys with a good linear relationship in the range of 0.3-3.0 μmol/L. As expected, this assay was successfully applied to the detection of Cys in human serum and plasma samples with recoveries ranging from 90.0% to 106.7%. Especially, the nanoprobe exhibits good cell membrane permeability and excellent biocompatibility by CCK-8 assay, which is favorable for bioimaging applications. Therefore, this fluorescent probe ensemble was further used for imaging of Cys in living cells, which suggests our proposed method has strong potential for clinical diagnosis. As a novel member of the quantum-dot family, the aN-dots hold great promise to broaden applications in biological systems.

Target-triggered NIR emission with a large stokes shift for the detection and imaging of cysteine in living cells.

Background autofluorescence from biological systems generally reduces the sensitivity of a fluorescent probe for imaging biological targets. Addressing this challenge requires the development of fluorescent probes that produce emission in the near-infrared region. Herein, we report the design and synthesis of a fluorescent probe that generates an NIR emission with a large Stokes shift upon the selective response to Cys over Hcy and GSH. The probe is designed to consist of two Cys-sensing sites, an acrylate ester and an aldehyde installed ortho to each other. The reaction of the probe with Cys triggers an excited state intramolecular proton transfer process upon photo-excitation, thereby producing an NIR emission with a large Stokes shift. Accordingly, this probe hold great promise for the selective detection of Cys in biological systems. We further demonstrate the capacity of this probe for Cys imaging in living cells.

Fluorescent Probes for the Selective Detection of Cysteine in Water

Two novel fluorescent chemodosimeters will be presented for the selective detection of cysteine over homocysteine and glutathione in aqueous solvent. First, a rhodamine-based fluorescent probe (1) will be reported. Masked with a para-hydroxybenzyl alcohol (HBA) unit, probe 1 initially showed a weak fluorescence but displayed a strong fluorescence through a series of reactions of Michael addition and intramolecular cyclization of cysteine, followed by deprotection of HBA. The caged probe (1) exhibited a selective and sensitive response toward cysteine over homocysteine and glutathione in HEPES buffer. Secondly, a fluorescein-based fluorescent probe will be discussed. A bromoacetyl functionalized fluorescein chemodosimeter (2) was utilized as a fluorescent probe for cysteine. The probe showed a selective and sensitive response to cysteine over homocysteine and glutathione in aqueous buffer through a rapid cyclization reaction. When cysteine was added, a fast fluorescence turn-on change of 2 was observed and applied to the in-vivo imaging of cysteine.