Probe For Cysteine Research Articles

A selective mitochondria-targeted fluorescent probe for imaging cysteine in drug-induced liver injury

Cysteine (Cys) is involved in many physiological processes. It's challenging to detect Cys selectively as it has similar chemical structure with other biothiols such as homocysteine (Hcy) and glutathione (GSH). In this work, a novel fluorescence probe toward mitochondrial cysteine, HPXI-6C, has been developed by employing carbonate as a new recognizing unit and hemicyanine as a chromophore. HPXI-6C exhibits a high selectivity to Cys over hydrogen sulfide, homocysteine and glutathione. The limit of detection toward Cys was determined to be 42nM. HPXI-6C can localize in mitochondria and produce strong fluorescence peaked at 725nm in response to Cys in tumor cells. The uptake and generation pathways of Cys in acetaminophen hepatotoxicity cells was revealed by using HPXI-6C. HPXI-6C has been successfully applied in imaging of Cys in drug-induced liver injury in vivo. The research demonstrated that HPXI-6C is powerful in monitoring Cys and is conducive to the early diagnosis of drug-induced liver injury diseases.

TDDFT elucidating the PET-Inhibition Mediated fluorescence enhancement in a Cysteine probe

TDDFT elucidating the PET-Inhibition Mediated fluorescence enhancement in a Cysteine probe

Developing a vanillin-derived imidazo-pyridin-containing fluorescent probe for imaging cysteine in living pulmonary cells under oxygen supply variation

In this work, derived from vanillin and imidazo-pyridin backbone, a fluorescent probe IPV-Cys was developed for imaging the cysteine (Cys) level in living pulmonary cells under oxygen supply variation. By mimicking the oxygen supply variation in both the solution test and cellular imaging, the optical performance and imaging effect of IPV-Cys was investigated. In the solution system, the oxygen supply variation caused no impact on the reporting signals. The fluorescence reporting signal intensity at 490nm suggested the enhancement along with the increase of the Cys concentration. The advantages of IPV-Cys included relatively high sensitivity, high stability, and high selectivity. On the basis of the low cyto-toxicity, IPV-Cys achieved the monitoring the endogenous Cys level in in living pulmonary cells and the impact of the oxygen supply variation by reporting fluorescence signals. The information here was meaningful for both the pre-clinical diagnosis and surgical techniques.

A ratiometric fluorescent probe for cysteine and glutathione differentiation and its application for cysteine detection in foods

A ratiometric fluorescent probe for cysteine and glutathione differentiation and its application for cysteine detection in foods

Two spirobifluene-based turn-on fluorescent probes for highly selective detection of Cysteine and the applications in cells two-photon fluorescence imaging

Two spirobifluene-based fluorescent probes SPF1 and SPF2, were designed and synthesized. The probes displayed "turn-on" fluorescence response for Cysteine. One of the challenges in developing a Cysteine probe is to secure high selectivity. SPF1/SPF2 can discriminate Cysteine from GSH as well as Hcy, and showed high substrate selectivity. The detection limit of SPF1 is 36nM, which is excellent comparing with other optical sensors for Cysteine. The sensing mechanism of SPF1/SPF2 was verified by experimental data and theoretical calculations. There was a good linear relationship between the fluorescence intensity of SPF1/SPF2 and the concentration of Cysteine. The MTT tests indicated that SPF1/SPF2 had low cytotoxicity and good biocompatibility. Theoretical calculations demonstrated that SPF1, SPF2, and their related reaction products with Cysteine exhibited good two-photon absorption properties. Finally, SPF1/SPF2 had been successfully applied to the imaging of Cysteine in living cells under two-photon excitation.

High-Contrast Photoacoustic Imaging of Localized Cysteine in Orthotopic Breast Cancer Enabled by A Totally-Caged Methylene Blue Probe.

High-contrast photoacoustic sensing imaging (PASI) was greatly determined by optical absorption changes of the absorbers usually enabled by activatable probes via controllably converting the absorbed electromagnetic energy to ultrasound waves. However, most of current photoacoustic probes still suffer from limited imaging contrast towards specific species because of their small absorption spectral changes in the near infrared (NIR) region. Herein, we developed a methylene blue-based photoacoustic probe with its NIR optical absorption totally caged, which could afford dramatical "OFF-to-ON" absorption transition for high-contrast photoacoustic imaging towards the localized cysteine. The rationally designed methylene blue-based probe for cysteine (MB-Cys) would keep in off state with almost no absorption in NIR region, while upon activated by cysteine through cyclization reaction with acrylates, it would reconstruct the π-conjugation system to release the free methylene blue with strong absorption centered at 665 nm (>130-fold enhancement). The unique responsive behavior could enable the PASI for photoacoustic mapping the cysteine in orthotopic breast cancer in a high-contrast manner. Therefore, this work established an up-to-date strategy to originally eliminate the background photoacoustic signal for PASI to accurately monitor cysteine in vivo.

A novel near-infrared fluorescent probe for cysteine and application in bioimaging

Abstract Cysteine (Cys) plays key roles in various pathological and physiological processes. Thus, the specific detection of Cys is a great necessity for the related disease diagnosis. Herein, we present a novel fluorescent probe based on a 2-benzothiazolyl-6-quinazolinyl-4-methylphenol moiety as fluorophore and a 2,4-dinitrobenzenesulfonyl moiety as detection functioned group. The probe presented a rapid and specific turn on response to Cys under physiological conditions, which could be convenient observed by the naked eyes. The detection mechanism was elucidated by HRMS, UV/vis absorption, fluorescence and DFT calculation. Furthermore, the probe was applied to monitor the endogenous Cys in living cells and mice.

Visualization of ischemia reperfusion injury of kidney and prediction of early allograft dysfunction after kidney transplantation using cysteine probe

Visualization of ischemia reperfusion injury of kidney and prediction of early allograft dysfunction after kidney transplantation using cysteine probe

Accurate identification of cysteine by a nucleophilic-reaction-induced conversion of an open-shell luminescent radical into closed-shell molecule

Sensors based on the disappear of unique optical and magnetic signals of luminescent radicals caused by the conversion from open-shell into closed-shell molecules have not been realized. Here, we report a multiple-channel Cysteine (Cys) probe by a luminescent tris(2,4,6-trichloro-3-nitrophenyl) methyl radical ( TTM • -3NO 2 ) with good selectivity and high sensitivity. Cys has been confirmed to react with TTM • -3NO 2 and generate closed-shell molecules, which causes the changes of fluorescence, colorimetry and electron paramagnetic resonance (EPR) of the radical. Interestingly, based on the above multiple-channel signal, we expanded the application of the radical sensor in RGB pattern, simulated clinical laboratory and fluorescent imaging. Our results not only display a promising Cys probe but also show a novel route for the application of organic radicals in sensing. • A stable luminescent radical (TTM • -3NO 2 ) was prepared with red doublet emission. • TTM • -3NO 2 radical can be used for multi-channel detection of Cys. • First detection of Cys using the idea of open-closed shell molecular conversion.

A NIR turn-on fluorescent probe for specific recognition of cysteine and its application in cells and zebrafish

A new turn-on fluorescent probe (DC-O-SBD) for cysteine (Cys) with a large Stokes shift was synthesized. Free DC-O-SBD had almost no fluorescence. After reacting with Cys, it released near-infrared (NIR) fluorescence at 655 nm. DC-O-SBD can respond to Cys quickly and had high specificity for Cys. Moreover, DC-O-SBD had a low detection limit (0.16 μM) and a large Stokes shift (155 nm). In addition, DC-O-SBD can efficiently detect Cys in HeLa cells and zebrafish.

A Rapid Near-Infrared Fluorescent Probe for Cysteine Based on Isophorone and its Application in B16 Cell Imaging.

A novel near-infrared fluorescent probe SWJT-5 based on dicyanoisophorone was synthesized. It achieved the rapid (within 40s) and discriminative detection of Cys over Hcy and GSH with a large Stokes shift (205nm). It showed high selectivity and sensitivity for Cys, and had an obvious enhancement of fluorescence emission. The detection limit was 0.43μM. This probe also had low background interference and little damage to biological samples. Therefore, SWJT-5 had been applied to bioimaging in living cells successfully.

An isothiocyanate-functionalized self-immolative near-infrared fluorescence probe for cysteine sensing and bioimaging in living systems

Biothiols play vital roles in human pathophysiology, with cysteine (Cys) a promising clinical biomarker for many diseases. Therefore, new tools to sensitively and specifically monitor Cys under physiological conditions and in living systems are urgently required. Consisting of a hemicyanine dye and isothiocyanate as the recognition group and self-immolative trigger, here we constructed a near-infrared (NIR) fluorescence probe named CyOH-NCS to specifically sense Cys. The hydroxyl-protected molecule maintained inactive fluorescence until specific attack of the isothiocyanate group by Cys to induce self-immolation and release of the native fluorophore as a NIR fluorescence output. Moreover, the CyOH-NCS probe was used to successfully visualize Cys in living cells, zebrafish and mice. Finally, hydrogen sulfide (H 2 S) release experiments demonstrated that the CyOH-NCS probe was a responsive H 2 S donor, indicating potential dual use in pathophysiological applications. • CyOH-NCS consists of hemicyanine dye with isothiocyanate integrated as the recognition group and self-immolative trigger. • CyOH-NCS showed high selectivity and sensitivity to cysteine over other biothiols. • CyOH-NCS successfully detects and visualizes cysteine in vitro and in vivo. • CyOH-NCS may have dual value as a molecular probe and H 2 S donor in pathophysiological applications.

Fluorescent cysteine probe based on a signal amplification unit, a catalyzed hairpin assembly reaction and Förster resonance energy transfer

This work developed a sensitive DNA-based fluorescent probe comprising a cysteine binding unit and a signal amplification unit based on a catalyzed hairpin assembly (CHA) reaction. The cysteine binding unit comprises a homodimer of single-stranded DNA (ssDNA) rich in cytosine and held together by silver ions. In the presence of cysteine, the homodimer is disintegrated because of cysteine-silver binding that liberates the ssDNA, which drives the CHA reaction in the signal amplification unit. Förster resonance energy transfer (FRET) was used to report the generation of the amplified double-stranded DNA (dsDNA) product. Under the optimal conditions, the probe provided a good linearity (100–1200 nM), a good detection limit (47.8 ± 2.7 nM) and quantification limit (159.3 ± 5.3 nM), and a good sensitivity (1.900 ± 0.045 μM−1). The probe was then used to detect cysteine in nine real food supplement samples. All results provided good recoveries that are acceptable by the AOAC, indicating that it has potential for practical applications.

First-in-Class: Cervical cancer diagnosis based on a urine test with fluorescent cysteine probe

In vitro diagnosis is key in diagnosing diseases and has recently become easily available. In vitro diagnostic techniques have been applied to various areas including the patient-tailored treatment development, disease progress tracking, and the cohort management. In this study, we developed the world's first in vitro cervical cancer diagnosis technology based on a urine test and verified its effectiveness with clinical urine samples of patients. In clinical practices, a Pap smear screening is used to detect cervical cancer, but it has limitations in its efficacy and from the uncomfortable sensation that women feel during the process. In this study, a new promising diagnostic method for cervical cancer was introduced using the molecular probe NPO-B, which selectively responds to cysteine (Cys) among amino acids in urine and exhibits fluorescence turn-on properties. The fluorescence signal of urine samples collected from about 1500 well characterized patients were analyzed and compared with the healthy control, and the results verified that cervical cancer could be diagnosed at a high true-positive ratio (74%). Our fluorescence-based cervical cancer diagnosis has advantages in terms that it only requires a simple fluorescence measuring device, a small amount of urine sample (200 μL), and a short diagnosis time (40 min). A noble way of spotting the cervical cancer with urine was introduced for the first time and is expected to be adopted to wider clinical practices including in vitro cervical cancer diagnosis or medical check-up requiring Cys sensing.

A novel dual-functional fluorescent probe for imaging viscosity and cysteine in living system.

Abnormal changes in intracellular viscosity and cysteine are both associated with several important biological processes such as reversible redox reactions, which play a pivotal role in the process of inflammation. However, it remains unclear how cysteine and viscosity are altered in inflammation. Herein, we firstly report a high-sensitivity and -selectivity near-infrared imaging probe (FCV) for tracking intracellular viscosity and endogenous cysteine. This dual-functional probe displays excellent photostability and large Stokes shifts. FCV exhibits a 54-fold enhancement in fluorescence emission at 560 nm with increasing Cys (λex = 420 nm) and an approximately 63-fold enhancement at 660 nm (λex = 460 nm) with increasing viscosity from 1.0 cP to 952.5 cP. Moreover, FCV reveals the synergistic relationship between viscosity and cysteine in the inflammation model of living cells and zebrafish for the first time. Thus, FCV is a promising vehicle to identify the changes in Cys and viscosity in associated diseases.

A highly selective colorimetric and fluorescent probe for cysteine sensing: Application in live cell imaging and test strips

Here, a coumarin-based probe 4-chloro-3-formyl-2-oxo-2H-chromen-7-yl acrylate (named CFCA ), which performed high efficient and specific recognition for cysteine (Cys), was successfully synthesized and characterized by NMR and MS. The CFCA probe showed colorimetric and “turn-on” fluorescent signals to Cys, and its color changes could be recognized by naked eyes. CFCA responded to Cys with the characteristics of rapid response time (less than 40 s), high selectivity, and excellent anti-interference. Among all kinds of samples, only Cys could significantly enhance the fluorescence intensity of the solution, which was not affected by the presence of other interferences. At the same time, within a certain concentration range, there was a good linear relationship between relative intensity of fluorescence and Cys concentration. The detection limit has been calculated to be as low as 0.33 μM. And the sensing mechanism of CFCA with Cys has been well confirmed by 1 H NMR and HR-MS spectra. Moreover, the fluorescence probe CFCA was successfully used for imaging Cys in living cells and processed into test strips for on-site analysis and testing. • A coumarin-based probe CFCA was successfully prepared, synthesized, and applied for Cys detection. • CFCA can perform high efficiency and specificity colorimetric and fluorescent double signal recognition for Cys. • CFCA has been used for imaging Cys in living cells and processed into test strips for on-site analysis and testing.

A Fast Dual-responsive OFF-ON Fluorescent Probe for Cysteine and Glutathione without Interference from Homocysteine.

Abnormal levels of biothiols, such as cysteine (Cys), homocystine (Hcy), and glutathione (GSH), are generally known to result in various diseases. Afast dual-responsive OFF-ON fluorescent probe HBO-AC was synthesized and developed. Non-fluorescent HBO-AC can sense Cys by regaining fluorescence at 444 nm within 10 min and a response to GSH by restoring fluorescence at 349 nm within 20 min. There is no mutual interference with Δλ ca. 100 nm. Anovel method was developed by utilizing a low reaction rate between HBO-AC and Hcy to eliminate common interference from Hcy. Asuccessful determination of Cys and GSH in fetal bovine serum (FBS) indicated that the probe had potential application for clinical diagnosis. Moreover, it was confirmed that HBO-AC can resist interference from protein to some extent, since FBS was not pretreated before use.

Inexpensive water soluble methyl methacrylate-functionalized hydroxyphthalimide: variations of the mycophenolic acid core for selective live cell imaging of free cysteine.

Evident from numerous studies, cysteine plays a crucial role in cellular function. Reactions with analyte also enables for molecular recognition to adhere to molecular therapeutic potential; integration between synthetic probes therefore allows for a potentially deep therapy-related interogation of biological systems (theranostics). The development of molecular cysteine probes with extremely accurate detection is still a key challenge for the field. The development of water-soluble organic molecular fluorescent probes able to efficiently distinguish common biothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) by chemical recognition means i.e. by (binding, cleavage) in biological systems is a greatly sought research challenge due to the similarity of the small sulfhydryl-containing species. Herein, we have developed a water-soluble and highly cell viable fluorescent organic molecule (log P = 0.82) for the selective detection of cysteine. The probe (Myco-Cys) shows a "turn-on" response with the cleavage ester linkage of the methacrylate as cysteine is encountered in solution. The probe shows strong fluorescence enhancement (16.5-fold) when treated with Cys (1 equiv., 10 μM) compared to closely related species such as amino acids, including HCy/GSH, and the limit of detection was determined as 45.0 nM. DFT calculations helped confirm the photomechanism of Myco-Cys. Furthermore, the sensing ability of the probe was demonstrated by living cell assays through the use of confocal fluorescence microscopy. Myco-Cys could selectively detect cysteine among biothiols. Myco-Cys was able to monitor the cysteine level, apart from the oxidative stress present in the form of H2O2 in A549 cells.

Theoretical study on the sensing mechanism of a coumarin-based fluorescent probe for biological thiols

The sensing mechanism of a reported fluorescence probe for cysteine, homocysteine and glutathione (Yin et al., 2018) has been investigated by time-dependent density functional theory. Experimental absorption and emission spectra of the probe before and after thiol addition were reproduced well by theoretical calculations, which validated the rationality of the method. Optimized geometries showed that the probe molecule had distinctly different geometries in its ground and excited states. It corresponded to the photoisomerization process and explained the weak fluorescence of the probe molecule. Moreover, by the potential energy curve scan, photoisomerization was further confirmed to be a spontaneous process with a barrier that barely existed. Frontier orbital analysis indicated that this photoinduced isomerization of the probe molecule derived from the antibonding character for lowest unoccupied molecular orbital at its CC double bond. In contrast, probe-thiol complexes exhibited similar geometries in their ground and excited states, which was responsible for the strong fluorescence of the probe with thiols. Due to distinct excited-processes, the probe can be used to sense thiols by monitoring the fluorescent change.

Isothiocyanate can be used as a highly specific recognition site for fluorescent cysteine probes

Cysteine (Cys) is an essential biothiol and amino acid molecule, playing important roles in many physiological and pathological events. As a biomarker of many diseases, Cys has important clinical significance. Accordingly, it is of great significance to develop an efficient and specific detecting method for Cys in life systems. We report herein a new approach that isothiocyanate (ITC) can be used as an effective new specific recognition site of Cys to develop effective probes for the detection of Cys in life systems. To demonstrate the effectiveness of this approach, ITC was attached to an easy-to-prepare coumarin fluorophore and a novel molecular probe (CM-NCS) was synthesized. As expected, the probe could respond rapidly, selectively, and sensitively to Cys and could be well used for the detection of Cys in live cells and zebrafish. All the results demonstrated that the new recognition site (ITC) would provide a good new choice to develop highly Cys-selective probes.