Biosensors and Bioelectronics 59 (2014) 35–39

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A simple and effective coumarin-based fluorescent probe for cysteine Xi Dai a, Qing-Hua Wu b, Peng-Chong Wang b, Jie Tian a, Yu Xu a, Sheng-Qing Wang a, Jun-Ying Miao b,n, Bao-Xiang Zhao a,nn a b

Institute of Organic Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P.R. China Institute of Developmental Biology, School of Life Science, Shandong University, Jinan 250100, P.R. China

art ic l e i nf o

a b s t r a c t

Article history: Received 3 December 2013 Received in revised form 5 March 2014 Accepted 6 March 2014 Available online 17 March 2014

Acrylic acid 3-acetyl-2-oxo-2 H-chromen-7-yl ester (ACA) was rationally designed and synthesized as a simple and effective fluorescent probe for sensing cysteine with high selectivity and naked-eye detection. The probe can detect cysteine by fluorescence spectrometry with a detection limit of 0.657 μM and can be used with calf serum and in live cell imaging. The conjugate addition/cyclization sequence mechanism of the reaction between ACA and cysteine was confirmed by ESI-MS and fluorescence spectra. & 2014 Elsevier B.V. All rights reserved.

Keywords: Fluorescent probe Cysteine Coumarin Conjugate addition Calf serum Cell imaging

1. Introduction Study of biothiols such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) has drawn much attention in recent years because of the varying biochemical functions of the thiols in physiological processes (Koopmans et al., 2013; Leung et al., 2013; Miyoshi et al., 2013; Verdoes et al., 2013). Cys plays a crucial role in maintaining biological redox homeostasis, in protein synthesis and in post-translational control (Huang et al., 2013a; Weerapana et al., 2010). Abnormal levels of Cys are closely related to certain diseases. For instance, Cys deficiency is implicated in slow growth rate, liver damage, hair depigmentation, muscle and fat loss, and skin lesions (Wang et al., 2009; Zhang et al., 2013). Elevated levels of Cys have been linked to neurotoxicity (Fan et al., 2013). Hence, the detection of Cys both in academic research and in clinical applications is important. Fluorescent probes are popularly used in small-molecularweight biothiol detection because of their high sensitivity and low detection limit and cost (Chen et al., 2012a; Kwon et al., 2011; Zhu et al., 2014; Sharma et al., 2014; Yuan et al., 2013a). A number of fluorescent probes for biothiols based on different mechanisms include the Michael addition (Jung et al., 2012), cyclization reaction with aldehyde (Hu et al., 2011), cleavage reaction by thiols n

Corresponding author. Corresponding author. Tel.: +86 531 88366425; fax: +86 531 88564464. E-mail addresses: [email protected] (J.-Y. Miao), [email protected] (B.-X. Zhao). nn

http://dx.doi.org/10.1016/j.bios.2014.03.018 0956-5663/& 2014 Elsevier B.V. All rights reserved.

(Cao et al., 2011), and others (Chand et al., 2013; Cho and Sessler, 2009; Li et al., 2014; Su et al., 2013). However, distinguishing Cys, Hcy and GSH is still difficult because of their structural similarity (Mei et al., 2013; Tang et al., 2013; Zheng et al., 2013). With the Michael addition of the thiol to the α,β-unsaturated ketone, discriminating Cys, Hcy and GSH is difficult because the nucleophilic activity of the mercapto group in the 3 thiols shows almost no difference (Long et al., 2013; Madhu et al., 2013; Yang et al., 2013a). A 1,8-naphthalimide–Cu(II) ensemble was reported as a new turn-on fluorescent probe for detecting thiols with high selectivity over other amino acids, but it cannot discriminate Cys, Hcy and GSH (Shi et al., 2013). Recently, a fluorescent probe based on combined use of photo-induced electron transfer and excitedstate intramolecular proton transfer mechanisms has been reported, but it cannot differentiate Cys, Hcy and GSH (Hong et al., 2014; Lan et al., 2011). A highly fluorescent gold nanocluster sensor could not discriminate Cys, Hcy and GSH (Park et al., 2013). A benzoxazine–hemicyanine-based probe also had difficulty distinguishing Cys, Hcy and GSH (Liu et al., 2013). In addition, although some probes were reported to detect cellular GSH, they interfered with the detection of Cys or Hcy (Lim et al., 2013; Lu et al., 2012; Na et al., 2012). Another critical question in the detection of Cys is that it often takes too much time (Huang et al., 2013b; Yuan et al., 2013b). Therefore, more efforts are needed. In this work, we designed and synthesized a fluorescent probe with the acrylic acid 3-acetyl-2-oxo-2H-chromen-7-yl ester (ACA), containing a latent coumarin fluorophore and a receptor of acrylate. The probe can well discriminate Cys from other thiols

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2. Experimental

20 min at 37 1C in the incubator, the reaction liquid underwent photoluminescence imaging measurement by luminescence microscopy (Nikon TE2000-E). Each reaction liquid was moved to black 96-well plates, and the photoluminescence image was recorded by use of a fluorescence microplate reader (Victor 3TM).

2.1. Apparatus and chemicals

2.4. Cell culture and cell imaging

Thin-layer chromatography (TLC) involved silica gel 60F254 plates (Merck KGaA) and column chromatography involved silica gel (mesh 200–300). 1H NMR (300 MHz) and 13C NMR (75 MHz) spectra were acquired on a Bruker Avance 300 spectrometer, with CDCl3 or DMSO used as a solvent and tetramethylsilane (TMS) as an internal standard. Melting points were determined with an XD-4 digital micro-melting-point apparatus. IR spectra were recorded with the infra-red (IR) spectrophotometer VERTEX 70 FT-IR (Bruker Optics). HRMS spectra were obtained on a Q-TOF6510 spectrograph (Agilent). UV–vis spectra were measured by a Hitachi U-4100 spectrophotometer. Fluorescent measurements were performed on a Perkin-Elmer LS-55 luminescence spectrophotometer. Quartz cuvettes with a 1-cm path length and 3-mL volume were used for all measurements. The pH was determined with a model PHS-3C pH meter. Unless otherwise stated, all reagents were purchased from Aladdin, J&K or Sinopharm Chemical Reagent Co. and used without further purification. Twice-distilled water was used throughout all experiments. The salts used in stock aqueous solutions of metal ions were KNO3, Ca(NO3)2  4H2O, NaNO3, Mg(NO3)2  6H2O, Zn(NO3)2  6H2O, Fe (NO3)3  9H2O.

HeLa cells were cultured in DMEM. The probe was dissolved in DMSO at a storage concentration of 50 mM. Cells were adherentcultured in 24-well culture plates for 12 h. HeLa cells were washed from the culture medium, incubated with 1.0 mL probe solution (5, 10, and 20 μM, respectively) for 5 h at 37 1C, then washed 3 times with phosphate buffered saline (PBS) and underwent imaging measurement by ultraviolet light with a Nikon TE2000-E fluorescent microscope. Imaging analysis involved use of ImageJ.

in a short time, even 30 min. ACA has been successfully used with calf serum and in live cell imaging.

2.2. Absorption and fluorescence spectroscopy The probe ACA was dissolved in ethanol for a stock solution (1 mM). The amino-acid (Cys, Hcy, GSH, arginine, aspartic acid, glutamic acid, glycine, histidine, lysine, proline, threonine, tryptophan, and tyrosine), cationic (K þ , Ca2 þ , Na þ , Mg2 þ , Zn2 þ , and Fe3 þ ), H2O2 and glucose stocks were all in deionized water at 10  2 M for absorption and fluorescence spectra analyses. Test solutions were prepared by displacing 100 μL of the stock solution and an appropriate aliquot of each testing species solution into a 10-mL volumetric flask, and the solution was diluted to 10 mL in a mixture of ethanol and water (2:3, v/v) buffered at pH 7.4 (HEPES buffer). The resulting solution was shaken well and incubated for 3 h at room temperature before recording spectra. For all measurements of fluorescence spectra, fluorescence escape efficiency was 1%, excitation wavelength 420 nm and scan speed 900 nm min  1. 2.3. Quantification of Cys in calf serum Calf serum (CS, from Hyclone) was divided into 6 groups, each group diluted with different multiples of PBS: no calf serum (PBS); dilution 100 times (0.01  CS), 20 times (0.05  CS), 5 times (0.2  CS), 2 times (0.5  CS); and not diluted (1  CS). Then CS was incubated with probe ACA dissolved in DMSO (stock solution: 0.1 M), and the reaction was blended with the use of an oscillator to a final concentration of ACA, 1 mM. After incubation for

3. Results and discussion 3.1. Synthesis and characterization Coumarins with one electron-donating substituent at the 7-position exhibit strong fluorescence (Huber et al., 2012; KisinFinfer and Shabat, 2013; Liu et al., 2013b; Sheshashena Reddy and Ram Reddy, 2013). We can use another electron-withdrawing group at the 7-position to induce fluorescence quenching (Liu et al., 2013a; Yang et al., 2013b). Therefore, the specific group is cleaved by a mercapto group to present fluorescence. We selected 7-hydroxy coumarin as the fluorophore because of its high fluorescent quantum yield, good photostability and low toxicity. The synthetic route of probe ACA is shown in Scheme 1. First, 3-acetyl-7-hydroxy-2H-chromen-2-one (2) was synthesized by the Knoevenagel reaction from 2,4-dihydroxybenzaldehyde (1) and ethyl acetylacetate (Chen et al., 2012b; Secci et al., 2011). Next, compound 3 (ACA) was readily synthesized by the reaction of intermediate 2 and acryloyl chloride in 80% yield (Erol et al., 2010). The structure of ACA was confirmed by IR, 1H NMR, 13C NMR and HRMS. 3.2. UV–vis absorption and fluorescence selectivity studies of probe ACA First, we studied the effect of ethanol content in solution on fluorescent intensity of free probe ACA and the probe towards Cys. The fluorescence increased initially, but decreased thereafter with increasing dose of ethanol (Fig. S1). According to fluorescence intensity (I) and relative value (I/I0), we selected an optimized EtOH/HEPES buffer (2:3, v/v, pH 7.4) solution for the spectral response. Our buffer system avoided toxic organic-containing solutions such as acetonitrile, DMF or DMSO as compared with reported probes for detecting biothiol (Yue et al., 2011; Wang et al., 2013a; Chen et al., 2012c; Shao et al., 2011; Mei et al., 2013; Das et al., 2013) and involved a reduced amount of ethanol solvent. When we added various amino acids (Cys, Hcy, GSH, arginine, aspartic acid, glutamic acid, glycine, histidine, lysine, proline, threonine, tryptophan, and tyrosine), metal ions (K þ , Ca2 þ , Na þ ,

Scheme 1. Synthesis of compound 3 (probe ACA)

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Because the pKa of Cys (8.30) was lower than that of Hcy (8.87) or GSH (9.20) (Iciek et al., 2004), under our experimental conditions (pH 7.4), the thiol of Cys was presumably changed to the thiolate, a better nucleophile in Michael addition reactions. Another reason for this preference could be a steric effect, because the thiol group of Cys is sterically less hindered than that of Hcy and GSH. The explanation may be applicable to many other thiol probes based on Michael addition reactions, cyclization reaction with aldehyde, or cleavage reaction by thiols (Wang et al., 2012; Guo, et al., 2012) and not be unique to ACA. 3.3. Reaction time of Cys To investigate the reaction time of ACA with Cys, we added Cys and GSH (6 equiv.) to a solution of ACA and recorded the fluorescence intensity of the detection system (Fig. S4). The fluorescent intensity at 456 nm increased with increasing reaction times, and the reaction of ACA with Cys was nearly complete within 40 min. A similar increase in fluorescence was observed for GSH, but the fluorescent intensity of GSH was lower during all times. At the same time, the free probe ACA showed no noticeable changes in solution. This reaction is relatively fast as compared with other reports (Das et al., 2013; Wang et al., 2013b). Some reported probes can rapidly detect thiols but with large amounts of thiols, such as excess 30 equiv. and even 1000 equiv. (Yuan et al., 2012; Jung et al., 2011; Long et al., 2013; Zhu et al., 2013). However, in the present work, we used only 6 equiv. thiols. 3.4. Quantification of Cys

Fig. 1. (a) UV–vis absorption spectra of acrylic acid 3-acetyl-2-oxo-2H-chromen-7yl ester (ACA; 1  10  5 M) with various analytes (6  10  5 M) in HEPES buffer solution (EtOH/HEPES ¼2:3, pH 7.4). Inset is photograph of ACA without and with cysteine (Cys) in light. (b) Fluorescence spectra of ACA (1  10  5 M) with various analytes (6  10  5 M) in HEPES buffer solution (EtOH/HEPES ¼ 2:3, pH 7.4). (λex ¼420 nm, slit: 6.0 nm/5.0 nm). Inset is a photograph of ACA without and with Cys on excitation at 365 nm with a UV lamp. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)

Fig. 2a shows the change in UV–vis absorbance with increasing dose of Cys. The absorbance at 424 nm increased and absorbance at around 340 nm decreased with increasing Cys concentration. Fig. 2b shows the increase in fluorescent intensity at around 456 nm with increasing dose of Cys. When Cys is at 6 equiv. of ACA, the fluorescent intensity nearly peaked, which is superior to analysis with some other probes (Jung et al., 2011; Yue et al., 2011). In addition, we found a linear correlation (k ¼94.9275, R2 ¼0.9970) between fluorescent intensity and concentration of Cys from 0 to 40 μM. The detection limit of Cys was 0.657 μM (Fig. S5). Therefore, ACA can detect Cys qualitatively and quantitatively by fluorescence spectrometry, which can be used with human plasma samples (Rusin et al., 2004). For biological samples, we successfully used ACA with calf serum and in living cell imaging. 3.5. Effect of pH on detection of Cys

Mg2 þ , Zn2 þ , and Fe3 þ ), H2O2 and glucose to HEPES-buffered ACA solution, we observed absorption and fluorescence bands. Cys increased absorbance at 424 nm (Fig. 1a), which was accompanied by a color change from colorless to yellowish by the naked eye. In addition, we observed marked fluorescence enhancement at 456 nm in the presence of Cys, which exhibits a strong blue fluorescence (Fig. 1b). Other analytes showed negligible change. GSH had lower UV–vis absorbance and fluorescence intensity toward the probe. We measured the fluorescent intensity with different concentrations of GSH, which nearly peaked at 10  4 M GSH (Fig. S2). Moreover, we examined interference of other related amino acids on monitoring Cys (Fig. S3). The presence of other analytes, even GSH, did not substantially affect the detection of Cys. Therefore, ACA possessed high selectivity toward Cys in the presence of other amino acids and metal ions. The addition of Hcy, an important biothiol similar to Cys, was unable to induce fluorescence enhancement. The results indicate that the selectivity of ACA between Cys and Hcy or GSH is higher than literature values (Wang et al., 2012; Yuan et al., 2012).

The effect of pH toward ACA with Cys is shown in Fig. S6. First, the fluorescent intensity was very weak, with nearly no change in pH 2.0–5.5. With or without Cys, ACA is stable under acidic conditions. With increasing pH from 6.0–9.5, the fluorescent intensity increased until the peak, at pH 9.5. Perhaps weak alkaline conditions promoted the reaction. With further increase in pH, the fluorescent intensity decreased until it was completely quenched, which might be due to opening of the lactone ring under stronger alkaline conditions. Therefore, we chose pH 7.4 for experimental conditions. As compared with early and even recent literature with pH Z9.0 (Rusin et al., 2004; Wei et al., 2013; Xu et al., 2013), our probe can function in the physiological pH range. 3.6. Mechanism of ACA in sensing Cys The condensation of acrylates with Cys can be used for preparation of substituted 1,4-thiazepines (Leonard and Ning, 1966). The acrylate group is usually used as a functional trigger moiety to detect Cys (Guo et al., 2012; Zhu et al., 2013). Here, we

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describe that the mechanism between ACA with Cys takes place as shown in Scheme 2 (Yang et al., 2011; Yin et al., 2013). The reaction involves the conjugate addition of Cys to an α,β-unsaturated carbonyl moiety to generate thioether (4), which can additionally

undergo an intramolecular cyclization to give the desired compounds 2 and 5. Furthermore, the reaction products of ACA with Cys underwent electrospray ionization mass spectral analyses, and peaks at m/z 203.0547, 174.0402 corresponding to compounds 2 and 5 were observed (Fig. S7). To confirm the mechanism, we investigated the fluorescence sensing behavior of precursor (2), ACA and ACA with Cys in HEPES buffer solution. ACA had only weak fluorescence because the fluorophore was quenched by the α,β-unsaturated ester (Fig. S8). After the addition of Cys, as expected, precursor 2 was produced and it triggered 13 times greater fluorescent intensity. 3.7. Application of probe ACA To verify the practical application of probe ACA, we incubated ACA (1 μM) with different concentrations of calf serum (CS) at 37 1C. Bright blue fluorescence appeared rapidly, which allowed for real-time detection. We obtained images after 20 min. Quantitative data were obtained by use of a fluorescence microplate reader (Fig. 3). The image showed excellent fluorescence intensity and was superior to our previous work and that of other research groups (Chen et al., 2012a; Wang et al., 2013a). To demonstrate the capability of the novel probe for fluorescence imaging of biothiols in living cells, living HeLa cells were incubated with ACA, with strong fluorescence observed (Fig. S9a). Moreover, the fluorescence intensity depended on the concentration of the probe (Fig. S10). To confirm that the fluorescence

Fig. 2. (a) UV–vis absorption spectra of ACA (1  10  5 M) with Cys (0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14 and 15 equiv.) in HEPES buffer solution (EtOH/ HEPES ¼ 2:3, pH 7.4). (b) Fluorescence spectra of ACA (1  10  5 M) with Cys (0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14 and 15 equiv.) in HEPES buffer solution (EtOH/HEPES ¼ 2:3, pH 7.4, λex ¼ 420 nm, slit: 6.0 nm/5.0 nm). Inset is plot of fluorescence intensity at 456 nm as a function of Cys equivalent. Data are mean 7SE (bars) (n¼ 3).

Fig. 3. Fluorescence intensity and images of ACA (1 μM) with different concentrations of calf serum. Ctr is no calf serum (PBS). Calf serum was diluted 100 times (1%), 10 times (10%), 5 times (20%), and 2 times (50%) with PBS and not diluted (100%) (n4 3, nn, p o 0.01).

Scheme 2. The proposed reaction mechanism of ACA and Cys.

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signals from cells were attributed to the reaction of ACA with biothiols, HeLa cells were pre-incubated with the thiol scavenger (N-ethylmaleiminde) to remove the endogenous intracellular thiols, then incubated with the probe. We observed almost no fluorescence (Fig. S9a). We quantified the fluorescence intensity using ImageJ (Fig. S9b) and confirmed that the probe was specific to thiols in living cells. 4. Conclusions We have developed a highly selective fluorescent probe ACA for distinguishing Cys from other amino acids at physiological pH. The fluorescence intensity of the probe enhances 13-fold and the color of ACA in buffer solution changes from colorless to yellowish with the addition of Cys. Probe ACA could serve as a naked-eye indicator for Cys. Furthermore, ACA can detect Cys at 0.657 to 40 μM. In addition, the mechanism of ACA on sensing Cys was confirmed by using ESI-MS and fluorescence spectra. Finally, ACA was successfully used for detecting Cys in calf serum and living imaging. Acknowledgments This study was supported by the National Basic Research Program of China (2010CB933504) and the National Natural Science Foundation of China (91313303). Appendix A. Supporting information Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1016/j.bios.2014.03.018. References Cao, X., Lin, W., Yu, Q., 2011. J. Org. Chem. 76, 7423–7430. Chand, R., Jha, S.K., Islam, K., Han, D., Shin, I.S., Kim, Y.S., 2013. Biosens. Bioelectron. 40, 362–367. Chen, H., Li, X., Wu, Y., Gao, W., Bai, R., 2012a. Dalton Trans. 41, 13292–13297. Chen, J., Liu, W., Ma, J., Xu, H., Wu, J., Tang, X., Fan, Z., Wang, P., 2012b. J. Org. Chem. 77, 3475–3482. Chen, Z., Wang, Z., Chen, J., Chen, X., 2012c. Biosens. Bioelectron. 38, 202–208. Cho, D.G., Sessler, J.L., 2009. Chem. Soc. Rev. 38, 1647–1662. Das, P., Mandal, A.K., Reddy, G.U., Baidya, M., Ghosh, S.K., Das, A., 2013. Org. Biomol. Chem. 11, 6604–6614. Erol, I., Sanli, G., Dİlek, M., Ozcan, L., 2010. J. Polym. Sci. Polym. Chem 48, 4323–4334. Fan, J., Wang, Z., Zhu, H., Fu, N., 2013. Sens. Actuators B 188, 886–893. Guo, Z., Nam, S., Park, S., Yoon, J., 2012. Chem. Sci 3, 2760–2765. Hong, K.-H., Kim, D.I., Kwon, H., Kim, H.-J., 2014. RSC Adv. 4, 978–982. Hu, M., Fan, J., Li, H., Song, K., Wang, S., Cheng, G., Peng, X., 2011. Org. Biomol. Chem. 9, 980–983. Huang, H., Shi, F., Li, Y., Niu, L., Gao, Y., Shah, S.M., Su, X., 2013a. Sens. Actuators B 178, 532–540. Huang, M., Thomas, D., Li, M., Feng, W., Chan, S., Majeti, R., Mitchell, B., 2013b. Leukemia 27, 1970–1980. Huber, A., Behnke, T., Wurth, C., Jaeger, C., Resch-Genger, U., 2012. Anal. Chem. 84, 3654–3661. Iciek, M., Chwatko, G., Lorenc-Koci, E., Bald, E., Wlodek, L., 2004. Acta Biochim. Polon. 51, 815–824. Jung, H.S., Ko, K.C., Kim, G.-H., Lee, A.-R., Na, Y.-C., Kang, C., Lee, J.Y., Kim, J.S., 2011. Org. Lett. 13, 1498–1501.

39

Jung, H.S., Pradhan, T., Han, J.H., Heo, K.J., Lee, J.H., Kang, C., Kim, J.S., 2012. Biomaterials 33, 8495–8502. Kisin-Finfer, E., Shabat, D., 2013. Bioorg. Med. Chem. 21, 3602–3608. Koopmans, T., van Haren, M., van Ufford, L.Q., Beekman, J.M., Martin, N.I., 2013. Bioorg. Med. Chem. 21, 553–559. Kwon, H., Lee, K., Kim, H.J., 2011. Chem. Commun. 47 (6), 1773–1775. Lan, M., Wu, J., Liu, W., Zhang, H., Zhang, W., Zhuang, X., Wang, P., 2011. Sens. Actuators B 156, 332–337. Leung, K.-H., He, H.-Z., Ma, V.P.-Y., Chan, D.S.-H., Leung, C.-H., Ma, D.-L., 2013. Chem. Commun. 49, 771–773. Li, X., Gao, X., Shi, W., Ma, H., 2014. Chem. Rev. 114, 590–659. Lim, S.-Y., Yoon, D.-H., Ha, D.Y., Ahn, J.M., Kim, D.I., Kown, H., Ha, H.-J., Kim, H.-J., 2013. Sens. Actuators B 188, 111–116. Liu, X.-D., Sun, R., Xu, Y., Xu, Y.-J., Ge, J.-F., Lu, J.-M., 2013. Sens. Actuators B 178, 525–531. Liu, X., Cole, J.M., Waddell, P.G., Lin, T.-C., McKechnie, S., 2013a. J. Phys. Chem. C 117, 14130–14141. Liu, X., Xu, Z., Cole, J.M., 2013b. J. Phys. Chem. C 117, 16584–16595. Long, L., Zhou, L., Wang, L., Meng, S., Gong, A., Du, F., Zhang, C., 2013. Org. Biomol. Chem. 11, 8214–8220. Lu, J., Song, Y., Shi, W., Li, X., Ma, H., 2012. Sens. Actuators B 161, 615–620. Madhu, S., Gonnade, R., Ravikanth, M., 2013. J. Org. Chem. 78, 5056–5060. Mei, J., Wang, Y., Tong, J., Wang, J., Qin, A., Sun, J.Z., Tang, B.Z., 2013. Chem. Eur. J. 19, 613–620. Miyoshi, T., Aoki, Y., Uno, Y., Araki, M., Kamatani, T., Fujii, D., Fujita, Y., Takeda, N., Ueda, M., Kitagawa, H., Emoto, N., Mukai, T., Tanaka, M., Miyata, O., 2013. J. Org. Chem. 78, 11433–11443. Leonard, N.J., Ning, R.Y., 1966. J. Org. Chem. 31, 3928–3935. Na, S.-Y., Park, S., Yun, M.-Y., Kwon, H., Kim, H.-J., 2012. Sens. Actuators B 174, 109–113. Park, K.S., Kim, M.I., Woo, M.A., Park, H.G., 2013. Biosens. Bioelectron. 45, 65–69. Rusin, O., St. Luce, N.N., Agbaria, R.A., Escobedo, J.O., Jiang, S., Warner, I.M., Dawan, F. B., Lian, K., Strongin, R.M., 2004. J. Am. Chem. Soc. 126, 438–439. Secci, D., Carradori, S., Bolasco, A., Chimenti, P., Yanez, M., Ortuso, F., Alcaro, S., 2011. Eur. J. Med. Chem. 46, 4846–4852. Shao, J., Guo, H., Ji, S., Zhao, J., 2011. Biosens. Bioelectron. 26, 3012–3017. Sharma, S., Dhir, A., Pradeep, C.P., 2014. Sens. Actuators B 191, 445–449. Sheshashena Reddy, T., Ram Reddy, A., 2013. Dyes Pigments 96, 525–534. Shi, Y.G., Yao, J.H., Duan, Y.L., Mi, Q.L., Chen, J.H., Xu, Q.Q., Gou, G.Z., Zhou, Y., Zhang, J.F., 2013. Bioorg. Med. Chem. Lett. 23, 2538–2542. Su, H., Qiao, F., Duan, R., Chen, L., Ai, S., 2013. Biosens. Bioelectron. 43, 268–273. Tang, Y., Yang, H.R., Sun, H.B., Liu, S.J., Wang, J.X., Zhao, Q., Liu, X.M., Xu, W.J., Li, S.B., Huang, W., 2013. Chem. Eur. J. 19, 1311–1319. Verdoes, M., Oresic Bender, K., Segal, E., van der Linden, W.A., Syed, S., Withana, N.P., Sanman, L.E., Bogyo, M., 2013. J. Am. Chem. Soc. 135, 14726–14730. Wang, H., Zhou, G., Mao, C., Chen, X., 2013a. Dyes Pigments 96, 232–236. Wang, L., Zhou, Q., Zhu, B., Yan, L., Ma, Z., Du, B., Zhang, X., 2012. Dyes Pigments 95, 275–279. Wang, S.Q., Wu, Q.H., Wang, H.Y., Zheng, X.X., Shen, S.L., Zhang, Y.R., Miao, J.Y., Zhao, B.X., 2013b. Analyst 138, 7169–7174. Wang, Y., Zheng, J., Zhang, Z., Yuan, C., Fu, D., 2009. Colloid Surf. A 342, 102–106. Weerapana, E., Wang, C., Simon, G.M., Richter, F., Khare, S., Dillon, M.B., Bachovchin, D.A., Mowen, K., Baker, D., Cravatt, B.F., 2010. Nature 468, 790–795. Wei, M., Yin, P., Shen, Y., Zhang, L., Deng, J., Xue, S., Li, H., Guo, B., Zhang, Y., Yao, S., 2013. Chem. Commun. 49, 4640–4642. Xu, Y., Li, B., Han, P., Sun, S., Pang, Y., 2013. Analyst 138, 1004–1007. Yang, X., Guo, Y., Strongin, R.M., 2011. Angew. Chem. Int. Ed. 50, 10690–10693. Yang, Y., Huo, F., Yin, C., Zheng, A., Chao, J., Li, Y., Nie, Z., Martinez-Manez, R., Liu, D., 2013a. Biosens. Bioelectron. 47, 300–306. Yang, Z., He, Y., Lee, J.H., Park, N., Suh, M., Chae, W.S., Cao, J., Peng, X., Jung, H., Kang, C., Kim, J.S., 2013b. J. Am. Chem. Soc. 135, 9181–9185. Yin, C., Huo, F., Zhang, J., Martinez-Manez, R., Yang, Y., Lv, H., Li, S., 2013. Chem. Soc. Rev. 42, 6032–6059. Yuan, L., Lin, W., Xie, Y., Zhu, S., Zhao, S., 2012. Chem. Eur. J. 18, 14520–14526. Yuan, L., Lin, W., Zheng, K., He, L., Huang, W., 2013a. Chem. Soc. Rev. 42, 622–661. Yuan, L., Lin, W., Zheng, K., Zhu, S., 2013b. Acc. Chem. Res. 46, 1462–1473. Yue, Y., Guo, Y., Xu, J., Shao, S., 2011. New J. Chem. 35, 61–64. Zhang, N., Qu, F., Luo, H.Q., Li, N.B., 2013. Biosens. Bioelectron. 42, 214–218. Zheng, C., Pu, S., Liu, G., Chen, B., Dai, Y., 2013. Dyes Pigments 98, 280–285. Zhu, B., Zhao, Y., Zhou, Q., Zhang, B., Liu, L., Du, B., Zhang, X., 2013. Eur. J. Org. Chem. 5, 888–893. Zhu, J., Song, X., Gao, L., Li, Z., Liu, Z., Ding, S., Zou, S., He, Y., 2014. Biosens. Bioelectron. 53, 71–75.

A simple and effective coumarin-based fluorescent probe for cysteine.

Acrylic acid 3-acetyl-2-oxo-2 H-chromen-7-yl ester (ACA) was rationally designed and synthesized as a simple and effective fluorescent probe for sensi...
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