Co-reporter:Xinyuan He;Yiming Hu;Wen Shi;Xiaohua Li
Chemical Communications 2017 vol. 53(Issue 68) pp:9438-9441
Publication Date(Web):2017/08/22
DOI:10.1039/C7CC05142E
We have, for the first time, developed a near-infrared fluorescent probe for aminopeptidase N by combining a hemicyanine and an alanyl residue. The probe exhibits high selectivity and sensitivity with a detection limit of 0.8 ng mL−1. With the probe, aminopeptidase N has been imaged in both cells and mice in vivo, indicating a promising tool for studying the function of the enzyme.
Co-reporter:Yu Fang;Wei Chen;Wen Shi;Hongyu Li;Ming Xian
Chemical Communications 2017 vol. 53(Issue 62) pp:8759-8762
Publication Date(Web):2017/08/01
DOI:10.1039/C7CC04093H
A new hemicyanine-based near-infrared fluorescence off–on probe with phenyl 2-(benzoylthio)benzoate as the recognition moiety to trap hydrogen polysulfides (H2Sn, n > 1) is developed, and is used for the sensitive imaging of H2Sn in cells and mice in vivo.
Co-reporter:Xiaofeng Wu;Xiaohua Li;Hongyu Li;Wen Shi
Chemical Communications 2017 vol. 53(Issue 16) pp:2443-2446
Publication Date(Web):2017/02/21
DOI:10.1039/C6CC09679D
A resorufin-based highly sensitive and selective fluorescence off–on probe with a new recognition moiety for tyrosinase is developed, and applied to detect and image endogenous tyrosinase activity in different living cells.
Co-reporter:Xiaofeng Wu; Wen Shi; Xiaohua Li; Dr. Huimin Ma
Angewandte Chemie 2017 Volume 129(Issue 48) pp:15521-15525
Publication Date(Web):2017/11/27
DOI:10.1002/ange.201708428
AbstractMonoamine oxidase (MAO) has two isoforms, MAO-A and MAO-B, which show different functions, and thus selective fluorescence imaging is important for biological studies. Currently, however, specific detection of MAO-A remains a great challenge. Herein, we report a new strategy for specific imaging of MAO-A through the design of fluorogenic probes combining the characteristic structure of an inhibitor of the target enzyme along with propylamine as a recognition moiety. The high specificity of our representative probe is demonstrated by imaging MAO-A in different live cells such as SH-SY5Y (high levels of MAO-A) and HepG2 (high levels of MAO-B), and further validated by western blot analyses. The superior specificity of the probe may enable the accurate detection of MAO-A in complex biosystems. Importantly, the use of the characteristic structure of an inhibitor, as demonstrated in this work, may serve as a general strategy to design specific recognition moieties for fluorogenic probes for enzymes.
Co-reporter:Xiaofeng Wu; Wen Shi; Xiaohua Li; Dr. Huimin Ma
Angewandte Chemie International Edition 2017 Volume 56(Issue 48) pp:15319-15323
Publication Date(Web):2017/11/27
DOI:10.1002/anie.201708428
AbstractMonoamine oxidase (MAO) has two isoforms, MAO-A and MAO-B, which show different functions, and thus selective fluorescence imaging is important for biological studies. Currently, however, specific detection of MAO-A remains a great challenge. Herein, we report a new strategy for specific imaging of MAO-A through the design of fluorogenic probes combining the characteristic structure of an inhibitor of the target enzyme along with propylamine as a recognition moiety. The high specificity of our representative probe is demonstrated by imaging MAO-A in different live cells such as SH-SY5Y (high levels of MAO-A) and HepG2 (high levels of MAO-B), and further validated by western blot analyses. The superior specificity of the probe may enable the accurate detection of MAO-A in complex biosystems. Importantly, the use of the characteristic structure of an inhibitor, as demonstrated in this work, may serve as a general strategy to design specific recognition moieties for fluorogenic probes for enzymes.
Co-reporter:Xinyuan He;Lihong Li;Yu Fang;Wen Shi;Xiaohua Li
Chemical Science (2010-Present) 2017 vol. 8(Issue 5) pp:3479-3483
Publication Date(Web):2017/05/03
DOI:10.1039/C6SC05712H
The liver, a main detoxification organ, has evolved a complex enzymatic system to respond to multiple pathological conditions, in which leucine aminopeptidase (LAP) has been reported to participate in detoxifying cisplatin in hepatoma cells and contribute to the intrinsic drug resistance. In vivo imaging of LAP activity in liver disease models is thus helpful to further understand the function of LAP in detoxification and medicine, but such an imaging approach is still lacking. Herein, we develop a selective and sensitive near-infrared fluorescent probe (HCAL) for this purpose. Using the probe, combined with confocal fluorescence imaging, we disclose the upregulations of LAP in acetaminophen-induced liver injury and tumor-bearing mice models. Supplementary acetylcysteine can suppress this upregulation, revealing that the LAP increase may be connected with a deficiency in biothiols. Moreover, HCAL has been used to image LAP in hepatoma cells, tumor tissues and xenograft tumor mice models successfully. These results demonstrate that HCAL may be a promising tool for studying the function of LAP in LAP-associated liver diseases.
Co-reporter:Qiuyu Gong, Wen Shi, Lihong Li and Huimin Ma
Chemical Science 2016 vol. 7(Issue 1) pp:788-792
Publication Date(Web):22 Oct 2015
DOI:10.1039/C5SC03600C
Cisplatin, a typical anticancer drug, is often used to treat different cancers, and leucine aminopeptidase (LAP) is known to be widely distributed in organisms from bacteria to humans, including various cancer cells. However, cancer cells display different intrinsic or acquired resistance toward cisplatin, and it is unclear whether intracellular LAP plays a role in the intrinsic drug resistance, mainly due to the lack of a sensitive detection approach for LAP because this enzyme usually exists at trace levels in cancer cells. Herein, by developing an ultrasensitive LAP fluorescent probe (detection limit 0.42 ng mL−1) and combining it with confocal fluorescence imaging, we analyze the concentration change of LAP in cancer cells such as HepG2 and A549 cells under cisplatin treatment. We find that a large increase in the LAP concentration occurs in HepG2 rather than in A549 cells. These different changes are further confirmed by an ELISA kit. A cell viability assay reveals that HepG2 cells with a higher level of LAP have much stronger resistance toward cisplatin than A549 cells, suggesting that LAP may serve as a simple indicator to reflect the relative resistance of different cancer cells. Importantly, inhibiting the expression of LAP with siRNA further decreases cell viability. These findings support that LAP may contribute to the intrinsic resistance of cancer cells toward cisplatin. In addition, the proposed probe may find more uses in studying the cellular LAP function, and improving chemotherapeutic cancer treatment.
Co-reporter:Qiuyu Gong, Lihong Li, Xiaofeng Wu and Huimin Ma
Chemical Science 2016 vol. 7(Issue 7) pp:4694-4697
Publication Date(Web):11 Apr 2016
DOI:10.1039/C6SC00951D
Pyroglutamate aminopeptidase 1 (PGP-1) can remove pyroglutamic acid from the N-terminus of a polypeptide, including some important anti-inflammatory proteins. Detecting the change and distribution of cellular PGP-1 in an inflammation process would be helpful to better understand the role of this enzyme. However, no report has been found on this subject, mainly due to the lack of a proper research approach. Herein, we develop such a new method by preparing a sensitive long-wavelength fluorescent probe combined with confocal fluorescence imaging. The probe, consisting of L-pyroglutamic acid and cresyl violet, exhibits high selectivity and sensitivity for PGP-1 under physiological conditions. With this probe, the up-regulation of PGP-1 in LO-2 cells under the stimulation of Freund's incomplete adjuvant and lipopolysaccharide (two main immunopotentiators) is revealed for the first time, and this up-regulation is also observed in typical phagocytic RAW264.7 cells, as evidenced by western blot and inhibition assays. Studies on the distribution of PGP-1 in cells using our probe showed that most PGP-1 is located in the cytoplasm, which is further supported by an immunofluorescence assay. Moreover, the inflammatory response induced by the immunopotentiators in either RAW264.7 or LO-2 cells is confirmed by measuring tumor necrosis factor alpha (a common inflammatory factor). The above findings indicate that cellular inflammation is accompanied by an increase in PGP-1, and PGP-1 may serve as a new indicator of cellular inflammatory response.
Co-reporter:Xinyuan He, Xiaofeng Wu, Wen Shi and Huimin Ma
Chemical Communications 2016 vol. 52(Issue 60) pp:9410-9413
Publication Date(Web):23 Jun 2016
DOI:10.1039/C6CC04628B
A specific fluorescent probe, designed by a substitution-rearrangement mechanism, can discriminate cysteine from other thiols. Using this probe, N-acetylcysteine is revealed to be superior to cysteine to replenish intracellular cysteine in cells.
Co-reporter:Jin Zhou, Wen Shi, Lihong Li, Qiuyu Gong, Xiaofeng Wu, Xiaohua Li, and Huimin Ma
Analytical Chemistry 2016 Volume 88(Issue 8) pp:4557
Publication Date(Web):March 29, 2016
DOI:10.1021/acs.analchem.6b00742
Tyrosinase is regarded as an important biomarker of melanoma cancer, and its metabolism is closely related to some severe skin diseases such as vitiligo. Since tyrosinase is mainly located in the melanosomes of melanocytes, a probe that can specifically detect and image tysosinase in melanosomes would be in urgent demand to study the behavior of the enzyme in cells, but unfortunately, no melanosome-targeting tyrosinase fluorescent probe has been reported so far to the best of our knowledge. In this work, we have developed such a new probe, Mela-TYR, which bears morpholine as a melanosome-targeting group and 4-aminophenol as a tyrosinase reaction group. The probe exhibits not only a highly sensitive and selective off-on response to tyrosinase via oxidization cleavage, but also an accurate targeting ability toward the acidic organelles of melanosomes and lyososomes, which is validated by colocalization experiments with mCherry-tagged melanosomes as well as DND-99 (a commercial dye). The probe has been used to image the relative contents of tyrosinase in different cells. Notably, because of the tyrosinase deficiency in normal lysosomes, the probe only fluoresces in melanosomes in principle although it can accumulate in other acidic organelles like lysosomes. By virtue of this property, the misdistribution of tyrosinase from melanosomes to lysosomes in murine melanoma B16 cells under the stimulation of inulavosin is imaged in real time for the first time. Moreover, the upregulation of melanosomal tyrosinase in live B16 cells under the stimulation of psoralen/ultraviolet A is detected with our probe, and this upregulation is further verified by standard colorimetric assay. The probe provides a simple, visual method to study the metabolism of tyrosinase in cells and shows great potential in clinical diagnosis and treatments of tyrosinase-associated diseases.
Co-reporter:Xiaofeng Wu, Lihong Li, Wen Shi, Qiuyu Gong, Xiaohua Li, and Huimin Ma
Analytical Chemistry 2016 Volume 88(Issue 2) pp:1440
Publication Date(Web):December 10, 2015
DOI:10.1021/acs.analchem.5b04303
Monoamine oxidase A (MAO-A) is known to widely exist in most cell lines in the body, and its dysfunction (unusually high or low levels of MAO-A) is thought to be responsible for several psychiatric and neurological disorders. Thus, a sensitive and selective method for evaluating the relative MAO-A levels in different live cells is urgently needed to better understand the function of MAO-A, but to our knowledge such a method is still lacking. Herein, we rationally design two new ratiometric fluorescence probes (1 and 2) that can sensitively and selectively detect MAO-A. The probes are constructed by incorporating a recognition group of propylamine into the fluorescent skeleton of 1,8-naphthalimide, and the detection mechanism is based on amine oxidation and β-elimination to release the fluorophore (4-hydroxy-N-butyl-1,8-naphthalimide), which is verified by HPLC analysis. Reaction of the probes with MAO-A produces a remarkable fluorescence change from blue to green, and the ratio of fluorescence intensity at 550 and 454 nm is directly proportional to the concentration of MAO-A in the ranges of 0.5–1.5 and 0.5–2.5 μg/mL with detection limits of 1.1 and 10 ng/mL (k = 3) for probes 1 and 2, respectively. Surprisingly, these probes show strong fluorescence responses to MAO-A but almost none to MAO-B (one of two isoforms of MAO), indicating superior ability to distinguish MAO-A from MAO-B. The high specificity of the probes for MAO-A over MAO-B is further supported by different inhibitor experiments. Moreover, probe 1 displays higher sensitivity than probe 2 and is thus investigated to image the relative MAO-A levels in different live cells, such as HeLa and NIH-3T3 cells. It is found that the concentration of endogenous MAO-A in HeLa cells is approximately 1.8 times higher than that in NIH-3T3 cells, which is validated by the result from an ELISA kit. Additionally, the proposed probes may find more uses in the specific detection of MAO-A between the two isoforms of MAO, thereby promoting our understanding of the behavior and function of MAO-A in living biosystems.
Co-reporter:Qiuyu Gong, Wen Shi, Lihong Li, Xiaofeng Wu, and Huimin Ma
Analytical Chemistry 2016 Volume 88(Issue 16) pp:8309
Publication Date(Web):July 22, 2016
DOI:10.1021/acs.analchem.6b02231
Dipeptide peptidase IV (DPPIV) and fibroblast activation protein (FAP) are isoenzymes. Evidence shows that DPPIV is related to antitumor immunity, and FAP may be a drug target in cancer therapy, making it seem that the two enzymes might have a synergistic role during the proliferation of cancer cells. Surprisingly, herein, we find an adverse action of DPPIV and FAP in the proliferation process by analyzing their changes with two tailor-made ultrasensitive fluorescent probes. First, the up-regulation of DPPIV and down-regulation of FAP in cancer cells under the stimulation of genistein are detected. Then, we find that MGC803 cells with a higher FAP but lower DPPIV level than SGC7901 cells exhibit a faster proliferation rate. Importantly, inhibiting the DPPIV expression with siRNA increases the proliferation rate of MGC803 cells, whereas the FAP inhibition decreases the rate. These findings suggest that the two enzymes play an adverse role during the proliferation of cancer cells, which provides us a new viewpoint for cancer studies.
Co-reporter:Yunyun Qiao, Yan Zhang, Caihong Zhang, Lihong Shi, Guomei Zhang, Shaomin Shuang, Chuan Dong, Huimin Ma
Sensors and Actuators B: Chemical 2016 Volume 224() pp:458-464
Publication Date(Web):1 March 2016
DOI:10.1016/j.snb.2015.10.080
•l-Amino acid oxidase (LAAOx) capped gold nanocluster (AuNCs) were synthesized.•The synthesis approach is a simple, straightforward and green.•The AuNCs is water soluble and with red fluorescent emission.•The AuNCs are used for rapid, highly selective and sensitive detection of Hg2+.l-Amino acid oxidase (LAAOx) capped gold nanoclusters (LAAOx-AuNCs) were prepared by “one-pot” method in aqueous solution. LAAOx-AuNCs showed red fluorescence emission, and this red fluorescence can turn blue in the presence of Hg2+, which is attributed to the effective fluorescence quenching by the strong Hg2+–Au+ interaction. Among various metal ions studied, Cu2+ ion, like Hg2+, was also found to efficiently quench the fluorescence intensity of LAAOx-AuNCs. However, we noted that ethylenediaminetetraacetate (EDTA) could recover the quenched fluorescence of LAAOx-AuNCs by Cu2+, but not that by Hg2+. Based on this behavior, LAAOx-AuNCs has been used as a probe to develop a rapid, highly selective and sensitive method for Hg2+detection. The response of the probe to Hg2+ exhibited a good linearity in the concentration range of 4.95 × 10−7–8.36 × 10−6 mol L−1 and 1.50 × 10−5–2.20 × 10−5 mol L−1, respectively. The detection limit was 58 nM Hg2+. Moreover, the applicability of our detection system is also verified by analysis of Hg2+ in tap water and river water.
Co-reporter:Jin Zhou, Lihong Li, Wen Shi, Xinghui Gao, Xiaohua Li and Huimin Ma
Chemical Science 2015 vol. 6(Issue 8) pp:4884-4888
Publication Date(Web):01 Jun 2015
DOI:10.1039/C5SC01562F
Macrophages, important cells of the innate immune system, can produce abundant HOCl in the cytoplasm to fight against bacteria. Recent studies suggest that mitochondria in macrophages play a role in antibacterial responses. During bacterial infection, however, it is uncertain whether HOCl is present in the mitochondria, mainly because of the lack of a suitable research method. Herein, by developing a new mitochondrial-targeting fluorescent HOCl probe, combined with confocal fluorescence imaging, we show for the first time that HOCl can appear in the mitochondria of macrophages (Raw264.7 cells) during bacterial infection, as confirmed with non-phagocytic cells and inhibitors as control experiments. Moreover, the developed probe exhibits an accurate mitochondrial-targeting ability, a fast response, and high selectivity and sensitivity (detection limit 9 nM), and is thus expected to be employed for further revealing the biological function of subcellular mitochondria.
Co-reporter:Xinghui Gao, Xiaohua Li, Lihong Li, Jin Zhou and Huimin Ma
Chemical Communications 2015 vol. 51(Issue 45) pp:9388-9390
Publication Date(Web):01 May 2015
DOI:10.1039/C5CC02788H
A simple and stable fluorescent off–on probe for discrimination of cysteine (Cys) from glutathione (GSH) has been developed by combining resorufin with 7-nitrobenzofurazan. The probe, displaying distinct emission patterns for Cys and GSH at just one excitation wavelength, can be used for simultaneous determination of Cys and GSH in human plasma.
Co-reporter:Zhe Wang, Xiaohua Li, Yanchao Song, Lihong Li, Wen Shi, and Huimin Ma
Analytical Chemistry 2015 Volume 87(Issue 11) pp:5816
Publication Date(Web):May 7, 2015
DOI:10.1021/acs.analchem.5b01131
A new upconversion luminescence nanoprobe for the detection of hyaluronidase has been developed by coupling the hyaluronic acid-bearing upconversion fluorescence nanoparticles (HA-UCNPs) with poly(m-phenylenediamine) (PMPD) nanospheres via covalent linkage. The nanoprobe alone exhibits an extremely low background signal owing to the effective fluorescence quenching by electron-rich PMPD and the near-infrared excitation characteristic (λex = 980 nm) of HA-UCNPs; upon reaction with hyaluronidase, however, a more than 31-fold fluorescence enhancement is produced. Compared with the corresponding nanosystem assembled via physical adsorption, the prepared nanoprobe shows a largely increased stability and a much higher signal-to-background ratio, which offers an ultrasensitive assay for hyaluronidase, with a detection limit of 0.6 ng/mL. The nanoprobe has been successfully used to determine hyaluronidase in human serum samples from both colorectal cancer patients and healthy people, disclosing that the serum hyaluronidase level in colorectal cancer patients is roughly 3 times higher than that in healthy people. Furthermore, the nanoprobe has also been employed to study the activity change of hyaluronidase affected by different concentrations of arsenate (a potential carcinogen), and the results show that even a low dosage of arsenate (50 μg/L) can raise the activity of hyaluronidase by about one-third, revealing the relationship between arsenate and the enzyme. The proposed method is not only simple but also highly sensitive, making it useful to assay hyaluronidase in relevant clinical samples.
Co-reporter:Lihong Li, Wen Shi, Zhe Wang, Qiuyu Gong, and Huimin Ma
Analytical Chemistry 2015 Volume 87(Issue 16) pp:8353
Publication Date(Web):July 15, 2015
DOI:10.1021/acs.analchem.5b01535
A new sensitive fluorescent probe with long analytical wavelengths for γ-glutamyl transpeptidase (GGT) assay has been developed by incorporating the γ-glutamyl group as a recognition unit into the fluorophore of cresyl violet (CV). The detection mechanism is based on the GGT-catalyzed cleavage of the γ-glutamyl group, followed by the release of CV, which leads to a distinct color change from light yellow to pink and a large fluorescence enhancement at 615 nm (λex = 585 nm). Under the optimized conditions, the fluorescence intensity of the probe is directly proportional to the activity of GGT in the range of 1–50 U/L with a detection limit of 5.6 mU/L. By virtue of its high sensitivity and long analytical wavelengths, the probe has been used to directly determine GGT in human serum samples from both healthy people and liver cancer patients, and the obtained results accord well with those acquired by commercial GGT fluorometric assay kit. The probe has also been employed to image endogenous GGT in living cells. Notably, with our probe the expression level of GGT in HepG2 cells under the action of sodium butyrate (an anticancer drug) was studied by fluorescence confocal microscopy, revealing that sodium butyrate can induce the upregulation of GGT in HepG2 cells in a dose- and time-dependent manner. This behavior of sodium butyrate has further been confirmed by lysate assay and inhibitor experiment. The proposed probe is rather simple and may find a wide use in the determination of GGT in clinical and biological samples.
Co-reporter:Zhao Li, Xinyuan He, Zhe Wang, Ronghua Yang, Wen Shi, Huimin Ma
Biosensors and Bioelectronics 2015 Volume 63() pp:112-116
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.07.024
•A new near-infrared fluorescence off–on probe is developed for nitroreductase assay.•The probe has an emission over 700 nm with high selectivity and sensitivity.•The probe is used to image the distribution of nitroreductase in zebrafish in vivo.•It is revealed that nitroreductase may mainly exist in zebrafish yolk sac.A new near-infrared fluorescence off–on probe is developed and applied to fluorescence imaging of nitroreductase in zebrafish in vivo. The probe is readily prepared by connecting 4-nitrobenzene as a quenching and recognizing moiety to a stable hemicyanine skeleton that can be formed via the decomposition of IR 780. The fluorescence off–on response of the probe to nitroreductase is based on the enzyme-catalyzed reduction of the 4-nitrobenzene moiety, followed by the 1,6-rearrangement-elimination and the fluorophore release. Compared with the existing nitroreductase probes, the proposed probe exhibits superior analytical performance such as near-infrared fluorescence emission over 700 nm as well as high selectivity and sensitivity, with a detection limit of 14 ng/mL. More importantly, the probe has been successfully applied to visualize the distribution of nitroreductase in living zebrafish in vivo, revealing that nitroreductase might mainly exist in zebrafish yolk sac. The superior properties of the probe make it of great potential use in other biosystems and in vivo studies.
Co-reporter:Xiaohua Li, Xinghui Gao, Wen Shi, and Huimin Ma
Chemical Reviews 2014 Volume 114(Issue 1) pp:590
Publication Date(Web):September 11, 2013
DOI:10.1021/cr300508p
Co-reporter:Yanchao Song, Zhe Wang, Lihong Li, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2014 vol. 50(Issue 99) pp:15696-15698
Publication Date(Web):24 Oct 2014
DOI:10.1039/C4CC07565J
Gold nanoparticles are functionalized as a nanoprobe with cresyl violet and porphyrin via hyaluronic acid. The nanoprobe becomes highly fluorescent in the presence of hyaluronidase or under ultraviolet irradiation, and can be used to target cancer cells via the overexpressed CD44 receptor for fluorescence imaging and phototherapy.
Co-reporter:Zhe Wang, Xiaohua Li, Duan Feng, Lihong Li, Wen Shi, and Huimin Ma
Analytical Chemistry 2014 Volume 86(Issue 15) pp:7719
Publication Date(Web):July 16, 2014
DOI:10.1021/ac5016563
A novel fluorescence nanoprobe for the detection of matrix metalloproteinase 2 (MMP2) has been developed by engineering the fluorescein isothiocyanate-labeled peptide onto the surface of poly(m-phenylenediamine) (PMPD) nanoparticles through covalent linkage. The nanoprobe itself displays a low background signal due to the effective fluorescence quenching by electron-rich PMPD, but its reaction with MMP2 causes 11-fold fluorescence enhancement. Compared with similar fluorescence nanosystems for MMP2 assembled through physical adsorption, the as-prepared nanoprobe is significantly more stable and displays a strikingly higher signal-to-background ratio, which leads to a high sensitivity for MMP2 assay, with a detection limit of 32 pM. Most notably, the nanoprobe has been successfully applied to determine MMP2 in human serum samples, demonstrating that the MMP2 level in serum from colorectal cancer (CRC) patients is 2 times higher than that from healthy people. Moreover, the nanoprobe has also been used to monitor MMP2 secreted by CRC cells that were grown under normoxic and hypoxic conditions, respectively, and the results show that the cells under hypoxic conditions produce higher level of MMP2 than those under normoxic conditions. Our method is simple and can offer a highly sensitive detection of MMP2 in relevant clinical samples.
Co-reporter:Lihong Li, Zhao Li, Wen Shi, Xiaohua Li, and Huimin Ma
Analytical Chemistry 2014 Volume 86(Issue 12) pp:6115
Publication Date(Web):May 20, 2014
DOI:10.1021/ac501288e
A highly sensitive and selective near-infrared (NIR) fluorescent probe, (E)-2-(2-(6-((2-carboxy-8-oxo-7-(2-phenylacetamido)-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methoxy)-2,3-dihydro-1H-xanthen-4-yl)vinyl)-3,3-dimethyl-1-propyl-3H-indol-1-ium (1), is developed for the determination of β-lactamase. The probe is designed and synthesized by incorporating the specific substrate (cephalosporin) of β-lactamase into a stable hemicyanine skeleton. The fluorescence of 1 itself is very weak due to the alkylation of the hydroxyl group of the hemicyanine fluorophore; however, β-lactamase can selectively react with its substrate (β-lactam ring) in the probe, thereby causing a spontaneous fragmentation. This action leads to the release of the fluorophore and a large fluorescence enhancement at 707 nm (λex = 680 nm). Under the optimized conditions, the fluorescence response of probe 1 is directly proportional to the concentration of β-lactamase in the range of 0.05–2 nM, with a detection limit of 0.02 nM. The validity of the probe has been confirmed by determining β-lactamase in human urine samples in comparison with that determined by iodimetry. Moreover, by taking advantage of its high sensitivity and NIR emission feature, the probe has also been utilized to image β-lactamase in three types of Staphylococcus aureus, including methicillin-resistant S. aureus ATCC BAA44, penicillin-resistant strain ATCC 11632, and penicillin-susceptible strain ATCC 29213, which clearly reveals the significantly different expression levels of β-lactamase in these S. aureus.
Co-reporter:Qiong-Qiong Wan;Xing-Hui Gao;Xin-Yuan He;Dr. Su-Ming Chen;Yan-Chao Song;Qiu-Yu Gong;Dr. Xiao-Hua Li ; Hui-Min Ma
Chemistry – An Asian Journal 2014 Volume 9( Issue 8) pp:2058-2062
Publication Date(Web):
DOI:10.1002/asia.201402364
Abstract
A new cresyl violet-based fluorescent off–on probe has been developed through a one-step synthesis for the detection of nitroreductase (NTR) and hypoxia. The detection mechanism is based on the NTR-catalyzed reduction of the probe to cresyl violet, accompanied with a large fluorescence enhancement at a long wavelength of 625 nm. The probe can detect NTR in aqueous solution with high selectivity and sensitivity, and the detection limit is 1 ng mL−1 NTR. Most importantly, the probe has been successfully used to image not only NTR and hypoxia in living cells, but also the distribution of NTR in zebrafish in vivo.
Co-reporter:Dr. Qiongqiong Wan;Dr. Suming Chen;Dr. Wen Shi;Lihong Li ;Dr. Huimin Ma
Angewandte Chemie 2014 Volume 126( Issue 41) pp:11096-11100
Publication Date(Web):
DOI:10.1002/ange.201405742
Abstract
Heat stroke is a life-threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome-targeting near-infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat-related pathology.
Co-reporter:Dr. Qiongqiong Wan;Dr. Suming Chen;Dr. Wen Shi;Lihong Li ;Dr. Huimin Ma
Angewandte Chemie International Edition 2014 Volume 53( Issue 41) pp:10916-10920
Publication Date(Web):
DOI:10.1002/anie.201405742
Abstract
Heat stroke is a life-threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome-targeting near-infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat-related pathology.
Co-reporter:Xinghui Gao, Xiaohua Li, Qiongqiong Wan, Zhao Li, Huimin Ma
Talanta 2014 Volume 120() pp:456-461
Publication Date(Web):March 2014
DOI:10.1016/j.talanta.2013.12.032
Co-reporter:Zhao Li, Xinghui Gao, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2013 vol. 49(Issue 52) pp:5859-5861
Publication Date(Web):14 May 2013
DOI:10.1039/C3CC42610F
A new spectroscopic off–on probe, 7-((5-nitrothiophen-2-yl)methoxy)-3H-phenoxazin-3-one, is developed and applied to real-time detection of nitroreductase produced by Escherichia coli.
Co-reporter:Qiongqiong Wan, Yanchao Song, Zhao Li, Xinghui Gao and Huimin Ma
Chemical Communications 2013 vol. 49(Issue 5) pp:502-504
Publication Date(Web):20 Nov 2012
DOI:10.1039/C2CC37725J
A new cresyl violet-based ratiometric fluorescence probe is developed and applied to fluorescence imaging of H2S in living cells and zebrafish in vivo.
Co-reporter:Duan Feng, Yanchao Song, Wen Shi, Xiaohua Li, and Huimin Ma
Analytical Chemistry 2013 Volume 85(Issue 13) pp:6530
Publication Date(Web):June 10, 2013
DOI:10.1021/ac401377n
Based on the high affinity of folic acid (FA) for folate receptor (FR) that is overexpressed on the surface of many human cancer cells, we have developed a simple fluorescence nanoprobe (1) with multiple capability (fluorescence off–on response and cell-targeting ability) for imaging of FR-positive cells by covalently linking both FA and Rhodamine B (RB) to graphene oxide (GO) through disulfide bonds. The nanoprobe shows a weak fluorescence due to the electron transfer from GO to RB. However, the specific binding of FA to FR-positive cells leads to the internalization of the nanoprobe into the cells. As a result, the disulfide bonds of 1 are cleaved by intracellular glutathione, causing the release of the RB moiety from GO and thereby the generation of fluorescence. Compared to most of the reported fluorescence always-on nanoprobes for imaging FR-positive cells, the present fluorescence off-on nanoprobe can not only produce a high signal/background ratio but also avoid the false positive results often caused by nonspecific adsorption of the always-on nanoprobes on the surface of nontarget cells. Notably, the proposed off–on nanoprobe has been demonstrated to distinguish the cells with different expression levels of FR by culturing and analyzing different cell mixtures (Hela/NIH-3T3 and Hela/MCF-7 cells). Moreover, the nanoprobe is capable of discriminating FR-positive from FR-negative cells even with similar morphology. This method is simple and selective for fluorescence imaging of FR-positive cells.
Co-reporter:Zhao Li, Xiaohua Li, Xinghui Gao, Yangyang Zhang, Wen Shi, and Huimin Ma
Analytical Chemistry 2013 Volume 85(Issue 8) pp:3926
Publication Date(Web):March 17, 2013
DOI:10.1021/ac400750r
A highly selective and sensitive fluorescence probe, 7-[(5-nitrofuran-2-yl)methoxy]-3H-phenoxazin-3-one (1), is developed for imaging the hypoxic status of tumor cells via the indirect detection of nitroreductase. The detection mechanism is based on the fact that nitroreductase can selectively catalyze the reduction of the nitro group in 1 to a hydroxylamine or amino group in the presence of reduced nicotinamide adenine dinucleotide as an electron donor that is indispensable, followed by the 1,6-rearrangement–elimination and the release of resorufin. As a result, the reaction produces a distinct color and fluorescence change from almost colorless and nonfluorescent to pink and strong red fluorescence. The fluorescence increase of probe 1 at λ550/585 nm is directly proportional to the concentration of nitroreductase in the range of 15–300 ng/mL, with a detection limit of 0.27 ng/mL. The ready reduction of the nitro group in 1 under hypoxic conditions leads to the establishment of a sensitive and selective fluorescence method for imaging the hypoxic status of tumor cells, and with this method Hela and A549 cells under normoxic and hypoxic conditions (even for different extents of hypoxia) can be differentiated successfully. This method is simple and may be useful for the imaging of disease-relevant hypoxia.
Co-reporter:Tingting Feng and Huimin Ma
Analyst 2013 vol. 138(Issue 8) pp:2438-2442
Publication Date(Web):13 Feb 2013
DOI:10.1039/C3AN36826B
A new approach is proposed for simple detection of adenosine deaminase (ADA) based on adenosine induced self-assembly of two pieces of single-stranded DNA (ssDNA). These ssDNA are two fragments of the aptamer that has a strong affinity for adenosine and are labeled with carboxyfluorescein and black hole quencher-1, respectively. The complementarities of the bases in the two pieces of ssDNA are insufficient to form a stable structure. In the presence of adenosine, however, the ssDNA can be assembled into the intact aptamer tertiary structure, which results in fluorescence quenching of the carboxyfluorescein-labeled aptamer fragment. As a result, the adenosine–ssDNA complex shows a low background signal, which is rather desired for achieving sensitive detection. Reaction of the complex with ADA causes a great fluorescence enhancement by converting adenosine into inosine that has no affinity for the aptamer. This behaviour leads to the development of a simple and sensitive fluorescent method for assaying ADA activity, with a detection limit of 0.05 U mL−1, which is more sensitive than most of the existing approaches. Furthermore, the applicability of the method has been demonstrated by detecting ADA in mouse serum samples.
Co-reporter:Jinxin Lu;Yanchao Song;Wen Shi;Xiaohua Li
Chinese Journal of Chemistry 2013 Volume 31( Issue 4) pp:472-478
Publication Date(Web):
DOI:10.1002/cjoc.201300061
Abstract
A novel fluorescent nanoprobe for glutathione S-transferase (GST) has been developed by incorporating 3,4-dinitrobenzamide (a specific substrate of GST) onto CdTe/ZnTe quantum dots. The probe itself displays a low background signal due to the strong quenching effect of the electron-withdrawing unit of 3,4-dinitrobenzamide on the quantum dots. However, GST can efficiently catalyze the nucleophilic substitution of reduced glutathione on the p-nitro group of the nanoprobe, leading to a large fluorescence enhancement. Most notably, this enhancement shows high selectivity and sensitivity towards GST instead of the other biological substances. With this nanoprobe, a simple fluorescence imaging method for intracellular GST has been established, and its applicability has been successfully demonstrated for imaging GST in different living cells, which reveals that A549 cells express GST about 3 times higher than NIH-3T3 and Hela cells.
Co-reporter:Ke Wang, Lixue Yang, Chuan Zhao, Huimin Ma
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 105() pp:29-33
Publication Date(Web):15 March 2013
DOI:10.1016/j.saa.2012.11.114
4-Amino-7-nitro-2,1,3-benzoxadiazole (ANBD) usually serves as a scaffold for developing fluorescent probes. In this paper, however, ANBD has been used as a chromogenic unit to design a new colorimetric probe, 4-(8-quinolyl)amino-7-nitro-2,1,3-benzoxadiazole (1), for rapid and visual detection of Hg2+. The reaction of 1 with Hg2+ in NaH2PO4–Na2HPO4 buffer (pH 7.0) containing 70% (v/v) acetonitrile forms a 1:1 complex, accompanying a red shift of the absorption maximum from 482 nm to 557 nm and a distinct color change from orange to violet. Moreover the color reaction exhibits a high selectivity and sensitivity to Hg2+ only, instead of other common metal ions. This behavior may be ascribed to the formation of a specific 1-Hg2+ complex, which is supported by 1H NMR titration experiments. The present study is not only a supplement to the detection method of Hg2+, but also a merit to the chemistry of 4-amino-7-nitro-2,1,3-benzoxadiazole.Graphical abstractHighlights► A new ANBD-based colorimetric probe 1 has been designed, synthesized and characterized. ► The probe 1 shows rapid, selective and visual detection of Hg2+, even in the presence of other competitive cations. ► The complexation mechanism of 1 with Hg2+ has been investigated by 1H NMR titration experiments. ► Deprotonation of NH group in ANBD moiety is found.
Co-reporter:Yanchao Song, Duan Feng, Wen Shi, Xiaohua Li, Huimin Ma
Talanta 2013 Volume 116() pp:237-244
Publication Date(Web):15 November 2013
DOI:10.1016/j.talanta.2013.05.022
•A parallel comparative method is used to evaluate the toxic effect of nanomaterials.•Relative toxicity of three common nanomaterials to live cells and plants is studied.•Relative toxicity is CdTe quantum dots⪢Au nanoparticles>carbon nanodots.•IC50 values of CdTe quantum dots, Au nanoparticles and carbon nanodots are obtained.•The quantitative data are useful for right choice of the nanomaterials in practice.By using confocal fluorescence microscopy and direct visualization, a parallel comparative investigation has been systematically made on the relative toxicity of three common nanomaterials, such as unmodified CdTe quantum dots (QDs), Au nanoparticles (Au NPs) and carbon nanodots (C-dots), to live cells as well as green gram sprouts. Bare CdTe QDs exert the most toxic effect on a variety of cell lines (HeLa, MCF-7, NIH/3T3 cells) as well as live plants (green gram sprouts). For cells, this toxic effect leads to the partial death of cells, the decrease of cell metabolic activity, the shrinkage of cells, the breakage of chromatin, the damage of cell membrane integrity, and the fragmentation of mitochondria; for green gram sprouts, the presence of CdTe QDs markedly inhibits their growth. Moreover, the toxic behaviors of CdTe QDs are dose- and time-dependent. Under the same conditions, Au NPs only decrease the metabolic activity of cells to a small extent, and do not affect the appearance of cellular/subcellular structures and the plant growth; interestingly, C-dots exert no obvious toxicity to both live cells and the growth of green gram sprouts, showing good biocompatibility. These parallel comparative studies clearly reveal that the relative toxicity of the three nanomaterials in their native forms is bare CdTe QDs⪢Au NPs>C-dots, whose IC50 values for normal NIH/3T3 cells are 0.98 μg/mL, 62 μg/mL, and >250 μg/mL, respectively. This quantitative information is of great importance for right choice of the nanomaterials in their practical applications.A parallel comparative investigation with confocal fluorescence microscopy and direct visualization has been systematically made on the toxic effect of three common nanomaterials, such as unmodified CdTe quantum dots, gold nanoparticles, and carbon nanodots, on live cells as well as green gram sprouts, and the results reveal that the relative toxicity of the three nanomaterials in their native forms is bare CdTe QDs⪢Au NPs>C-dots.
Co-reporter:Yanchao Song, Wen Shi, Wei Chen, Xiaohua Li and Huimin Ma
Journal of Materials Chemistry A 2012 vol. 22(Issue 25) pp:12568-12573
Publication Date(Web):30 Apr 2012
DOI:10.1039/C2JM31582C
In this work, an efficient approach for targeting and detecting cancer cells has been developed through the design of the assembly of fluorescent carbon nanodots and folic acid (C-dots–FA), which is endocytosible by the overexpressed folate receptor (FR) molecule. The fluorescent C-dots were prepared by a facile microwave pyrolysis method, but their surfaces were passivated with 4,7,10-trioxa-1,13-tridecanediamine, so that active amino groups could be engineered for the further conjugation with FA. The uptake of the designed C-dots–FA by HeLa cancer cells, as revealed by confocal laser scanning microscopy, is via receptor-mediated endocytosis, which is further confirmed by competition experiments as well as a comparative study with FR-negative MCF-7 cells. The proposed method shows excellent biocompatibility, and, most notably, its applicability to discriminating FR-positive cancer cells from normal cells has been successfully demonstrated by culturing and analyzing the first model cell mixture of NIH-3T3 and HeLa cells, which makes it of great potential for cancer diagnosis studies.
Co-reporter:Wen Shi and Huimin Ma
Chemical Communications 2012 vol. 48(Issue 70) pp:8732-8744
Publication Date(Web):21 Jun 2012
DOI:10.1039/C2CC33366J
Spectroscopic probes have been extensively investigated and used widely in many fields because of their powerful ability to improve analytical sensitivity, and to offer greater temporal and spatial resolution (in some cases a molecule event may be visualized by the naked eye). So far, different photophysical mechanisms, such as charge transfer, photo-induced electron transfer and fluorescent resonance energy transfer, have been employed to develop various spectroscopic probes with superior properties. However, these photophysical mechanisms depend on the energy levels of molecular orbitals, which are usually difficult to accurately determine. This would lead to the poor prediction of analytical performance of the designed probe. Instead, the change of π-conjugated systems induced by chemical reactions is often accompanied by a distinct alteration in spectroscopic signal, which is more predictable and is of high signal/background ratio. This mechanism can serve as an effective measure for developing excellent spectroscopic probes, but to our knowledge, has not been systematically summarized. In this feature article, we review the development of spectroscopic probes with changeable π-conjugated systems, which is catalogued according to the fluorochromes: fluorescein, rhodamine, spiropyran, squaraine, coumarin, cyanine, etc. Two main strategies for constructing these spectroscopic probes, including ring-closing reaction and nucleophilic addition reaction, are summarized, and the merits and limitations of the probes are discussed.
Co-reporter:Wei Chen, Zhao Li, Wen Shi and Huimin Ma
Chemical Communications 2012 vol. 48(Issue 22) pp:2809-2811
Publication Date(Web):18 Jan 2012
DOI:10.1039/C2CC17768D
A new resorufin-based probe is developed, which exhibits a rapid and sensitive color and a fluorescence off–on response to benzoyl peroxide (BPO) in aqueous media containing 10% ethanol via deboronation. The probe has been applied to the simple detection of BPO in real samples such as wheat flour and antimicrobial agent.
Co-reporter:Yangyang Zhang, Wei Chen, Duan Feng, Wen Shi, Xiaohua Li and Huimin Ma
Analyst 2012 vol. 137(Issue 3) pp:716-721
Publication Date(Web):13 Dec 2011
DOI:10.1039/C2AN15952J
A new resorufin-based spectroscopic probe, 7-(p-acetoxyphenylmethyloxy)-3H-phenoxazin-3-one (1), has been developed for detecting carboxylesterase activity. The probe is designed by introducing p-acetoxyphenylmethyloxy as a bifunctional moiety to resorufin. The p-acetoxyphenylmethyloxy moiety not only quenches the spectroscopic signal of resorufin, but also serves as a recognition unit for carboxylesterase. As a result, the prepared latent spectroscopic probe 1 shows very low background signal, which is rather desired for achieving sensitive detection. The specific cleavage of the carboxylic ester bond by carboxylesterase induces the hydrolysis of the probe, resulting in the release of resorufin and thereby the recovery of both color and fluorescence signal. This behaviour leads to the development of a simple and sensitive fluorescent method for assaying carboxylesterase activity, with a detection limit of 8.6 × 10−5 U mL−1, which is much more sensitive than the existing fluorescence approaches. Moreover, experimental results showed that the probe 1 is cell membrane permeable, and its applicability has been demonstrated for monitoring carboxylesterase activity in HeLa cells.
Co-reporter:Tingting Feng, Duan Feng, Wen Shi, Xiaohua Li and Huimin Ma
Molecular BioSystems 2012 vol. 8(Issue 5) pp:1441-1445
Publication Date(Web):14 Feb 2012
DOI:10.1039/C2MB05379A
This paper presents a novel sensor to detect proteolytically active prostate-specific antigen (PSA) by assembling a purpose-designed FITC-labeled peptide with graphene oxide (GO). The fluorescence of the dye-labeled peptide was quenched in the presence of GO. Reaction of the sensor with PSA cleaves the peptide, leading to the release of the dye moiety and a great increase in fluorescence intensity in a dose- and time-dependent manner, and PSA can be quantified accordingly. This approach is simple compared to existing methods since the GO-peptide-based sensor is easily assembled and detection can be achieved without the involvement of complicated procedures. Moreover, the applicability of the method has been demonstrated by detecting PSA in spiked urine samples.
Co-reporter:Dr. Wen Shi;Dr. Xiaohua Li ;Dr. Huimin Ma
Angewandte Chemie 2012 Volume 124( Issue 26) pp:6538-6541
Publication Date(Web):
DOI:10.1002/ange.201202533
Co-reporter:Dr. Wen Shi;Dr. Xiaohua Li ;Dr. Huimin Ma
Angewandte Chemie International Edition 2012 Volume 51( Issue 26) pp:6432-6435
Publication Date(Web):
DOI:10.1002/anie.201202533
Co-reporter:Dr. Suming Chen;Wei Chen;Dr. Wen Shi ;Dr. Huimin Ma
Chemistry - A European Journal 2012 Volume 18( Issue 3) pp:925-930
Publication Date(Web):
DOI:10.1002/chem.201101764
Abstract
Ferrocence and its derivatives have long been known to be a class of stable organometallic compounds, and their dissociation usually occurs under harsh conditions. Here we report a new type of ferrocene derivatives, 4,4-difluoro-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene and 4,4-difluoro-2,6-diethyl-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene, which surprisingly can hydrolyze under mild conditions. These two derivatives, initially developed as donor–acceptor probes for reactive oxygen species by incorporating the electron donor of ferrocene as a quencher into the fluorophore of BODIPY (boron dipyrromethene difluoride), barely emit fluorescence. Upon reaction with H2O under the irradiation of natural light at room temperature, however, both of the probes display a dramatic color change and fluorescence retrievement. Detailed experimental results reveal that the reaction of the probes with H2O leads to the removal of a cyclopentadiene unit and iron(II), yielding a BODIPY derivative that retains the other cyclopentadiene unit and shows a large fluorescence enhancement (over 100-fold). Moreover, the increase in fluorescence intensity is directly proportional to microamount of water, and the presence of both light and H2O is indispensable in the reaction, which makes the present system of great potential not only for determining water but also for forming a AND logic gate. Most importantly, the present mild dissociation reaction may give a new insight into the stability of ferrocene and its derivatives.
Co-reporter:Jinxin Lu, Yanchao Song, Wen Shi, Xiaohua Li, Huimin Ma
Sensors and Actuators B: Chemical 2012 Volume 161(Issue 1) pp:615-620
Publication Date(Web):3 January 2012
DOI:10.1016/j.snb.2011.11.009
A highly selective Nile Red-based fluorescent probe has been designed, synthesized and applied for fluorescence imaging of reduced glutathione (GSH) in live cells. The probe is constructed by incorporating 2,4-dinitrobenzenesulfonyl (DBS) group as a quencher into the Nile Red fluorophore, and itself shows weak fluorescence due to the strong intramolecular charge transfer process. Nucleophilic aromatic substitution of GSH leads to the removal of the DBS unit in the probe, accompanying a large increase in fluorescence intensity. Under the optimized conditions, the fluorescence enhancement value is directly proportional to the concentration of GSH in the range of 0.5–6 μM, with a detection limit of 43 nM (k = 3). Moreover, the probe features long-wavelength emission of about 650 nm, which could avoid the interference of short-wavelength fluorescence from biological matrixes. These properties facilitate the probe's applicability in bioimaging, and such an application has been demonstrated on fluorescence imaging of GSH in HeLa cells.
Co-reporter:Duan Feng, Yangyang Zhang, Tingting Feng, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2011 vol. 47(Issue 38) pp:10680-10682
Publication Date(Web):02 Sep 2011
DOI:10.1039/C1CC13975D
A graphene oxide–peptide based fluorescence sensor has been developed for matrix metalloproteinase 2 (MMP2), and its applicability has been demonstrated by monitoring the concentration of MMP2 secreted by HeLa cells, revealing that HeLa cells with a density of 5.48 × 105cells per mL can produce 22 nM in cell culture media in 24 h.
Co-reporter:Chengdong Sun, Wen Shi, Yanchao Song, Wei Chen and Huimin Ma
Chemical Communications 2011 vol. 47(Issue 30) pp:8638-8640
Publication Date(Web):01 Jul 2011
DOI:10.1039/C1CC12174J
A new strategy that utilizes the interaction between NO and a selenide is reported for fluorescence detection of NO, in which rhodamine B selenolactone serves as a model selenide.
Co-reporter:Wei Chen, Wen Shi, Zhao Li, Huimin Ma, Yang Liu, Jinghua Zhang, Qingjun Liu
Analytica Chimica Acta 2011 Volume 708(1–2) pp:84-88
Publication Date(Web):5 December 2011
DOI:10.1016/j.aca.2011.10.002
Benzoyl peroxide (BPO) as a brightener is often added to wheat flour, and excessive use of this food additive is receiving increasing concern. Herein, a simple and fast method for fluorescence detection of BPO is proposed based on consecutive chemical reactions. In this approach, BPO first oxidizes Fe2+ into Fe3+ and the resulting Fe3+ then induces the opening of the spirolactam ring of a new rhodamine derivative, N-methoxy rhodamine-6G spirolactam, switching on fluorescence of the detection system. More importantly, the fluorescence response of the reaction system to BPO is rather rapid and sensitive, with a detection limit of 6 mg kg−1 (k = 3), which makes it to be of great potential use in food safety analysis. The applicability of the proposed method has been successfully demonstrated on the determination of BPO in wheat flour samples.Graphical abstractA simple and fast method for fluorescence detection of benzoyl peroxide in wheat flour by N-methoxy rhodamine-6G spirolactam (1) is proposed based on consecutive chemical reactions.Highlights► Benzoyl peroxide can oxidize Fe2+ into Fe3+. ► Fe3+ selectively induces the opening of rhodamine spirolactam ring. ► The two reactions led to the development of a new fluorescent method for benzoyl peroxide. ► The method is simple and fast, and is used to detect benzoyl peroxide in wheat flour.
Co-reporter:ChengDong Sun;JianMing Chen;Yang Liu;JingHua Zhang
Science China Chemistry 2011 Volume 54( Issue 7) pp:1101-1108
Publication Date(Web):2011 July
DOI:10.1007/s11426-011-4275-1
A new rhodamine derivative, N-(3-carboxy)acryloyl rhodamine B hydrazide (CARB), has been synthesized, and its unusual spectroscopic reaction with Cu2+ has been investigated. The derivative exhibits a rapid and reversible non-fluorescent absorption upon coordination to Cu2+, which is a rather unusual phenomenon for rhodamine B derivatives. Stoichiometric measurements using the Job’s method and the molar ratio method reveal that one CARB molecule combines two Cu2+ ions, and the two Cu2+ ions play different roles: one opens the spirocyclic structure and the other quenches the fluorescence of the xanthene moiety. This reaction mechanism is supported by a comparative study on the model compound N-acryloyl rhodamine B hydrazide as well as by the density functional theory calculations. Furthermore, the absorption response of CARB is highly selective for Cu2+ over other common ions, which implies that CARB may be used as a colorimetric probe for the rapid visual detection of Cu2+.
Co-reporter:Jia Jia
Science Bulletin 2011 Volume 56( Issue 31) pp:
Publication Date(Web):2011/11/01
DOI:10.1007/s11434-011-4645-2
A water-soluble fluorescence resonance energy transfer (FRET) probe for hypochlorous acid (HOCl), dansyl rhodamine B piperazinoacetohydrazide, was designed, synthesized and characterized. The dansyl moiety in the probe acted as a FRET donor and the rhodamine moiety acted as a FRET acceptor. The two moieties were connected by a HOCl-cleavable active bond, and cleavage of this linker decreased the FRET efficiency and increased the fluorescence intensity of the donor at 501 nm. The water solubility of the probe was improved compared with other probes by introduction of the cationic rhodamine fluorophore. As a result, the probe could be used to detect HOCl in aqueous biosystems with a linear range of 2–10 μmol/L and a detection limit of 80 nmol/L (signal-to-noise = 3). The probe was successfully applied to fluorescence imaging of HOCl in HeLa cells.
Co-reporter:Yangyang Zhang, Wen Shi, Duan Feng, Huimin Ma, Yan Liang, Jianru Zuo
Sensors and Actuators B: Chemical 2011 Volume 153(Issue 1) pp:261-265
Publication Date(Web):31 March 2011
DOI:10.1016/j.snb.2010.10.008
Exposure to mercury causes severe damage to plants, animals and even humans. Concern over mercury toxicity has encouraged the development of efficient, sensitive, and selective methods for the in vivo detection of mercury. Although a variety of studies have been published describing fluorescence imaging of mercury in animal cells and tissues, no in vivo monitoring has been developed for plant systems until now. In this paper, we report the semi-quantitative fluorescence imaging of Hg2+ ions in a common model plant Arabidopsis thaliana (A. thaliana), with rhodamine B thiolactone (RBS) as a novel Hg2+ probe. The experimental results show that RBS is plant cell wall and cell membrane permeable, and the probe responds selectively to Hg2+ ions instead of the other species in plant systems. Real-time monitoring of Hg2+ absorption in roots of A. thaliana by RBS shows that saturation of Hg2+ uptake could occur in a short period of 3 days at most. The transportation and accumulation of Hg2+ ions in roots of A. thaliana have also been studied, revealing that most of Hg2+ ions reside in root cap and meristematic zone, and only a small amount of Hg2+ ions can reach the maturation zone. This indicates that the interaction of Hg2+ ions with any Hg2+-philic species including proteins in these regions may be responsible for plant poisoning and even death.
Co-reporter:Jinxin Lu, Chengdong Sun, Wei Chen, Huimin Ma, Wen Shi, Xiaohua Li
Talanta 2011 Volume 83(Issue 3) pp:1050-1056
Publication Date(Web):15 January 2011
DOI:10.1016/j.talanta.2010.11.023
A novel fluorescent probe is designed and synthesized for the determination of cysteine in biological samples by incorporating 2,4-dinitrobenzenesulfonyl (DBS) group as a quencher into the BODIPY skeleton. The BODIPY-based probe itself shows weak fluorescence due to the strong intramolecular charge transfer process. Upon reaction with cysteine, however, the probe produces a rapid and large fluorescence enhancement through the removal of the DBS unit by nucleophilic aromatic substitution. This valuable property leads to the development of a new and simple method for cysteine assay. Under the optimized conditions, the fluorescence enhancement value is directly proportional to the concentration of cysteine in the range 2–12 μM, with a detection limit of 30 nM (S/N = 3). The applicability of the developed method has been successfully demonstrated on the determination of non-protein cysteine in human serum. Compared to most of the existing fluorescent probes proposed for cysteine, the BODIPY-based one exhibits an excellent overall performance in terms of selectivity, sensitivity and simplicity.
Co-reporter:Xiaohua Li, Wen Shi, Suming Chen, Jia Jia, Huimin Ma and Otto S. Wolfbeis
Chemical Communications 2010 vol. 46(Issue 15) pp:2560-2562
Publication Date(Web):11 Mar 2010
DOI:10.1039/C001225D
A new cyanine-based near-infrared fluorescent probe has been developed for monitoring tyrosinase activity.
Co-reporter:Duan Feng, Yangyang Zhang, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2010 vol. 46(Issue 48) pp:9203-9205
Publication Date(Web):28 Oct 2010
DOI:10.1039/C0CC02703K
A new method with high simplicity, rapidity and sensitivity has been developed for visual detection of phosgene based on the distinct color change of cysteine-modified gold nanoparticles.
Co-reporter:Wen Shi ; Shuna Sun ; Xiaohua Li
Inorganic Chemistry 2010 Volume 49(Issue 3) pp:1206-1210
Publication Date(Web):December 30, 2009
DOI:10.1021/ic902192a
Rhodamine B selenolactone has been designed, synthesized, and characterized as a new fluorescent probe for imaging both Hg2+ and Ag+ in live cells to better understand their distinct toxicities to organisms. The probe is designed based on the fact that selenium has a strong affinity for mercury and silver, and is constructed by incorporating a Se atom into the spirocyclic structure of rhodamine. It exhibits a rapid and specific spectroscopic off-on response to Hg2+ and Ag+ instead of other species, with detection limits of 23 nM Hg2+ and 52 nM Ag+. Moreover, the probe is membrane-permeable, and can react with Ag+ even in the presence of Cl− because of the higher affinity of Se than Cl− for Ag+, which makes it of potential use for imaging not only Hg2+ but also Ag+ in live cells. This applicability has been demonstrated by imaging Hg2+ and Ag+ in Hela cells. It is observed that the reaction of Ag+ with the probe inside the cells occurs much slower than that of Hg2+, which is ascribed to the high concentration of cellular chloride ions inhibiting the formation of sufficient free Ag+. The present finding is helpful to get an insight into the different interaction mechanism of Hg2+ and Ag+ with cells, and more applications of the probe may be expected for studying the behaviors of Hg2+ and Ag+ in various biosystems.
Co-reporter:Suming Chen, Jinxin Lu, Chengdong Sun and Huimin Ma
Analyst 2010 vol. 135(Issue 3) pp:577-582
Publication Date(Web):18 Jan 2010
DOI:10.1039/B921187J
A highly specific ferrocene-based fluorescent probe, (9-anthryl)ethenylferrocene, has been designed, synthesized and characterized for fluorescence imaging of hypochlorous acid (HOCl) in live cells. The design strategy for the probe is based on the strong quenching effect of electron-donor ferrocene on anthracene fluorescence via an intramolecular charge transfer process, and is accomplished through constructing the conjugated molecule by using a cleavable double bond as a linker. The double bond in the probe reacts selectively with HOCl rather than the other reactive oxygen species (e.g., ˙OH, ˙O2−, 1O2, and H2O2) in pH 7.4, accompanied by more than 100-fold fluorescence enhancement. Moreover, the probe is cell membrane permeable, and its applicability has been successfully demonstrated for fluorescence imaging of HOCl in HeLa cells.
Co-reporter:Jia Jia, Wei Chen, Huimin Ma, Ke Wang and Chuan Zhao
Molecular BioSystems 2010 vol. 6(Issue 10) pp:1829-1833
Publication Date(Web):06 Jul 2010
DOI:10.1039/C005223J
Rhodamine B piperazinoacetohydrazine (RBPH) is used as a bifunctional probe for the N-terminal specific modification of a thermophilic enzyme (T. lanuginosus xylanase), and the modification effect on the thermostability of the enzyme is investigated. The probe RBPH, bearing a spectroscopic unit of rhodamine B, a carbonyl-specific labeling unit of hydrazine and a linker of piperazine, not only has a stable always-on spectroscopic response, but also exists in a cationic form. These properties enable RBPH to serve as a bifunctional probe (simultaneous introduction of stable spectroscopic signal and positive charge) for the protein modification, and such an application has been successfully demonstrated on the N-terminal labeling of T. lanuginosus xylanase. A temperature-dependent inactivation study shows that the modification of T. lanuginosus xylanase by RBPH hardly changes its thermostability, in other words, a small change in electric charge of the N-terminal region caused by introducing one positive charge is not enough to alter the thermostability of the enzyme. This reveals a conservative property of the N-terminal domain for electric charge change, and such a property may result from the fact that the N-terminal domain of the enzyme already has 4 charged residues, which can produce strong electrostatic interactions, thereby making the domain quite stable.
Co-reporter:Liying Cui, Wen Shi, Jingxia Wang, Yanlin Song, Huimin Ma and Lei Jiang
Analytical Methods 2010 vol. 2(Issue 5) pp:448-450
Publication Date(Web):13 Apr 2010
DOI:10.1039/C0AY00154F
The photonic crystal (PC)-based light-amplification method has been demonstrated for Hg2+ detection. A Hg2+ detection limit of ca. 10 nM was achieved via the amplification effect of a blue band edge of the PC film.
Co-reporter:Jia Jia;Ke Wang Dr.;Wen Shi;Suming Chen;Xiaohua Li Dr. Dr.
Chemistry - A European Journal 2010 Volume 16( Issue 22) pp:6638-6643
Publication Date(Web):
DOI:10.1002/chem.200902660
Abstract
A new water-soluble reagent, rhodamine B piperazinoacetohydrazine (RBPH), with improved spectroscopic and reaction properties, has been developed and characterized for pyruvic acid labeling. The reagent RBPH is designed and synthesized by using rhodamine B as a spectroscopic unit, and hydrazine as a carbonyl-specific labeling unit; the two units are connected by a well-chosen linker of piperazine, which prohibits the formation of the nonfluorescent spirocyclic structure of rhodamine B, thereby keeping the spectroscopic response of the reagent in a stable state. Such a design enables RBPH not only to maintain its excellent spectroscopic properties over a wide pH range, but also to exist as a stable cation with high water solubility. Moreover, the hydrazino group of RBPH is expected to react selectively with carbonyl compounds under mild conditions through the rapid formation of hydrazones. These important features make RBPH of great potential use in the labeling of aldehydes or ketones in various biosystems, and such an application of RBPH as a precolumn derivatizing reagent has been successfully demonstrated on the analysis of pyruvic acid in human serum by high-performance liquid chromatography with common UV/Vis detection.
Co-reporter:Xinqi Chen, Jia Jia, Huimin Ma, Shujuan Wang, Xiaochun Wang
Analytica Chimica Acta 2009 Volume 632(Issue 1) pp:9-14
Publication Date(Web):19 January 2009
DOI:10.1016/j.aca.2007.08.025
Rhodamine B hydroxylamide (1) is characterized as a highly selective and sensitive fluorescence probe for Cu2+. Under the optimized conditions, the probe exhibits specific absorbance-on and fluorescence-on responses to Cu2+ only. This remarkable property may allow Cu2+ to be detected directly in the presence of the other transition metal ions, and such an application has been demonstrated to human serum. The reaction mechanism is also investigated and proposed as that the hydroxylamide group of 1 binds Cu2+, and the subsequent complexation of Cu2+ displays a high catalytic activity for the hydrolytic cleavage of the amide bond, causing the release of fluorophore (rhodamine B) and thereby the retrievement of absorbance and fluorescence. The recovered fluorescence intensity is proportional to the concentration of Cu2+ in the range 1–20 μM. The detection limit for Cu2+ is 33 nM (k = 3). The reaction mechanism described here may be useful for developing excellent spectroscopic probes with cleavable active bonds for other analytes.
Co-reporter:ShuJuan Wang;SuMing Chen
Science China Chemistry 2009 Volume 52( Issue 6) pp:809-814
Publication Date(Web):2009 June
DOI:10.1007/s11426-009-0027-x
The polarity-sensitive fluorescent probe, 3-(4-chloro-6-p-glyoxalphenoxy-1,3,5-triazinylamino)-7-(dimethylamino)-2-methylphenazine, was used to analyze the local structure of apo-α-lactalbumin by detecting the polarity and conformational changes of the arginine residue (Arg10) domain. The polarity of the Arg10 domain in both native and heat-denatured apo-α-lactalbumin was determined, which corresponds to a dielectric constant of 16, and the hydrophobic core near the Arg10 was found to be conservative for heating. Meanwhile, the effect of Ca2+ binding on the conformational changes of the Arg10 domain was studied, revealing that the hydrophobic core near the Arg10 is insensitive to the binding of Ca2+.
Co-reporter:Suming Chen;Xiaohua Li Dr. Dr.
ChemBioChem 2009 Volume 10( Issue 7) pp:1200-1207
Publication Date(Web):
DOI:10.1002/cbic.200900003
Co-reporter:Xiaochun Wang, Lihong Guo, Huimin Ma
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 73(Issue 5) pp:875-878
Publication Date(Web):1 September 2009
DOI:10.1016/j.saa.2009.04.008
The change trend of the local environment of Cys34 domain in bovine serum albumin has been studied as a function of pH value by using thiol-specific and polarity-sensitive fluorescent probe 3-(4-chloro-6-p-maleimidylphenoxyl-1,3,5-triazinylamino)-7-dimethylamino-2-methyl-phenazine. The local polarity of the Cys34 domain is found to rise with the increase of pH values, and the corresponding dielectric constant is raised from 12.8 at pH 6.0 to 23.3 at pH 9.1. The result shows that the environment of the Cys34 domain is rather hydrophobic in normal state at pH 6.0 and becomes a little hydrophilic in the course of N→B transition, which may be attributed to the slight unfolding of the protein and thus the increasing of exposure of the previously relatively buried Cys34. In addition, the increased dielectric constant (23.3) is much lower than that (80.1) of water, suggesting that the unfolding of bovine serum albumin does not cause the full exposure of the Cys34 to the aqueous media during the transition.
Co-reporter:Ke Wang, Wen Shi, Jia Jia, Suming Chen, Huimin Ma
Talanta 2009 Volume 77(Issue 5) pp:1795-1799
Publication Date(Web):15 March 2009
DOI:10.1016/j.talanta.2008.10.021
To develop viscosity-sensitive fluorescent probes, five different substituted 2-phenylbenzo[g]quinoxaline derivatives (3a–e) were designed and synthesized by using benzo[g]quinoxaline as a fluorophore and phenyl ring bearing a rotatable single bond as a viscosity-sensitive unit. The fluorescence properties of these compounds were investigated in the media of the ethylene glycol–glycerol mixture with varied viscosity. It is found that 2-(4-hydroxyphenyl)benzo[g]quinoxaline (3d) and 2-(4-dimethylaminophenyl)-benzo[g]quinoxaline (3e) carrying stronger electron-donating groups in the phenyl ring show more sensitive fluorescence response to viscosity, revealing their potential use in viscosity detection and the key role of the substituted groups. The effects of solvent polarity and pH on the fluorescent properties of 3d and 3e were also discussed. The present study might be useful in developing viscosity-sensitive fluorescent probes.
Co-reporter:Wen Shi and Huimin Ma
Chemical Communications 2008 (Issue 16) pp:1856-1858
Publication Date(Web):27 Feb 2008
DOI:10.1039/B717718F
Rhodamine B thiolactone is developed as a simple chemosensor towards Hg2+ in neutral aqueous solution with high selectivity.
Co-reporter:Xiaochun Wang, Shujuan Wang and Huimin Ma
Analyst 2008 vol. 133(Issue 4) pp:478-484
Publication Date(Web):19 Feb 2008
DOI:10.1039/B717230C
The design and synthesis of a new polarity-sensitive fluorescent probe, 3-(4-chloro-6-p-maleimidylphenoxyl-1,3,5-triazinylamino)-7-dimethylamino-2-methylphenazine, is reported for characterizing the local polarity and structure, such as the thiol domain, of a protein. The probe comprises a polarity-sensitive fluorophore (neutral red moiety) and a thiol-specific labeling group (maleimidyl moiety). The probe exhibits a sensitive response of shift of fluorescence maximum emission wavelength to solvent polarity, but not to pH and temperature, which makes the probe suitable for determining the local polarity change of a protein denatured by pH or temperature. The application of this kind has been first demonstrated for the polarity detection of the Cys121 domain of β-lactoglobulin. It is found that the polarity of the Cys121 domain corresponds to a dielectric constant of 17.3, and this value hardly alters after heat treatment, which may be attributed to the improved thermal reversibility by the Cys121 modification. The simple mixture of the probe and the protein at pH 5.6 is also studied, revealing that the free probe prefers to bind to an outer hydrophobic region. Heat treatment of the mixture causes the modification of Cys121 residues; this modification does not completely destroy the calyx but results in the opening of a channel for the probe to enter the calyx of β-lactoglobulin. These results show that Cys121 plays an important role not only in the thermal reversibility but also in the accessibility of the calyx to a ligand. The strategy presented here further indicates that the combination of polarity-sensitive fluorescence probe with site-specific labeling may serve as a powerful means for elucidating structures and properties of proteins.
Co-reporter:Xinqi Chen Dr.;Xiaochun Wang;Shujuan Wang;Wen Shi;Ke Wang Dr.
Chemistry - A European Journal 2008 Volume 14( Issue 15) pp:4719-4724
Publication Date(Web):
DOI:10.1002/chem.200701677
Abstract
A new rhodamine B-based fluorescent probe for the hypochlorite anion (OCl−) has been designed, synthesized, and characterized. The probe comprises a spectroscopic unit of rhodamine B and an OCl−-specific reactive moiety of dibenzoylhydrazine. The probe itself is nearly nonfluorescent because of its spirolactam structure. Upon reaction with OCl−, however, a largely enhanced fluorescence is produced due to the opening of the spirolactam ring by the oxidation of the exocyclic hydrazide and subsequently the formation of the hydrolytic product rhodamine B. Most notably, the fluorescence-on reaction shows high sensitivity and extremely high selectivity for OCl− over other common ions and oxidants, which makes it possible for OCl− to be detected directly in their presence. In addition, the reaction mechanism has been investigated and proposed. The OCl− anion selectively oxidizes the hydrazo group in the probe, and forms the analogue of dibenzoyl diimide, which in turn hydrolyzes and releases the fluorophore. The reaction mechanism that is described here might be useful in developing excellent spectroscopic probes with cleavable active bonds for other species.
Co-reporter:Zhijuan Bao;Shuna Sun;Jun Li;Xinqi Chen;Suying Dong
Angewandte Chemie International Edition 2006 Volume 45(Issue 40) pp:
Publication Date(Web):19 SEP 2006
DOI:10.1002/anie.200602144
Seeing is believing: Treatment of tryptophan with formic acid and hydrochloric acid generates a violet-blue color. The reaction is very specific, and can be used to identify tryptophan in a mixture of amino acids, or corroborate the existence of tryptophyl groups in peptides or proteins (see picture; A: blank; B: a mixture of 9 representative amino acids; C: tryptophan; D: mixture (B) and tryptophan; E: reduced glutathione; F: egg-white albumin).
Co-reporter:Guanxin Zhang, Xiaohua Li, Huimin Ma, Deqing Zhang, Jun Li and Daoben Zhu
Chemical Communications 2004 (Issue 18) pp:2072-2073
Publication Date(Web):13 Aug 2004
DOI:10.1039/B405272B
4,4′(5′)-Bis[2-(9-anthryloxy)ethylthio]tetrathiafulvalene bearing an electron-rich tetrathiafulvalene unit and a luminophore of anthracene shows a highly selective and sensitive chemiluminescence response to singlet oxygen.
Co-reporter:Xuejun Duan;Zhen Zhao;Jianping Ye Dr. Dr.;Andong Xia Dr.;Guoqiang Yang Dr.;Chih-Chen Wang
Angewandte Chemie International Edition 2004 Volume 43(Issue 32) pp:
Publication Date(Web):9 AUG 2004
DOI:10.1002/anie.200460072
The folding/unfolding of a protein structure has been studied through measuring the donor–donor energy migration between two fluorescent probes (F) coupled selectively to the N termini of the homodimeric DsbC protein (see picture). The fluorometric strategy provides a convenient and reliable method to investigate conformational changes in dimeric proteins.
Co-reporter:Xuejun Duan;Zhen Zhao;Jianping Ye Dr. Dr.;Andong Xia Dr.;Guoqiang Yang Dr.;Chih-Chen Wang
Angewandte Chemie 2004 Volume 116(Issue 32) pp:
Publication Date(Web):9 AUG 2004
DOI:10.1002/ange.200460072
Das Falten und Entfalten einer Proteinstruktur wurde anhand der Donor-Donor-Energiewanderung zwischen zwei Fluoreszenzsonden (F) untersucht, die selektiv an die N-Termini des homodimeren DsbC-Proteins gekuppelt sind (siehe Bild). Die Fluorometrie-Strategie bietet eine bequeme und verlässliche Methode, um Konformationsänderungen in dimeren Proteinen zu analysieren.
Co-reporter:Xiaohua Li, Huimin Ma, Suying Dong, Xuejun Duan, Shuchuan Liang
Talanta 2004 Volume 62(Issue 2) pp:367-371
Publication Date(Web):6 February 2004
DOI:10.1016/j.talanta.2003.08.004
The synthesis of a novel fluorescent probe, 3-epoxypropoxy fluorescein (EPF), and its properties for labeling of histidine are described. The probe contained a fluorescein fluorophore with long-wavelength response and an active epoxy labeling group. In alkaline media EPF reacted selectively with histidine, rather than with other amino acids, causing a large increase in fluorescence intensity and thereby allowing a selective detection of histidine. This fluorescence increase resembled that of the fluorescein diaion with the increase of the media basicity, suggesting that the addition reaction of histidine with the epoxy group provides the fluorophore moiety with a basic molecular environment. As an application of this probe, fluorescent labeling of histidine in human serum was attempted and the obtained results were in agreement with those given by using histidine–nickel complex adsorptive voltammetry. Further, the relative S.D. of the method was 1.8% for 10 replicate determinations of 0.55 μM histidine. When 10 μM of EPF was used, the linear range for histidine was 0.007–10 μM with a detection limit (S/N=3) of 0.001 μM.
Co-reporter:Ming Sun;Dihua Shangguan;Lihua Nie;Xiaohua Li;Shaoxiang Xiong;Guoquan Liu;Wolfram Thiemann
Biopolymers 2003 Volume 72(Issue 6) pp:
Publication Date(Web):10 OCT 2003
DOI:10.1002/bip.10484
A new fluorescent probe for PbII, p-nitrophenyl 3H-phenoxazin-3-one-7-yl phosphoric acid (NPPA), was designed and synthesized by linking resorufin (serving as a fluorophore and electron acceptor) to p-nitrophenol (serving as a fluorescence quencher and electron donor) through phosphodiester bonds. When NPPA was irradiated with light, intramolecular fluorescence self-quenching took place because of the photoinduced electron transfer from the donor to the acceptor. However, upon the addition of PbII, the phosphate ester bonds in the probe were cleaved and the fluorophore was released, accompanying the retrievement of fluorescence. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy), 2003
Co-reporter:Lihua Nie, Huimin Ma, Ming Sun, Xiaohua Li, Meihong Su, Shuchuan Liang
Talanta 2003 Volume 59(Issue 5) pp:959-964
Publication Date(Web):10 April 2003
DOI:10.1016/S0039-9140(02)00649-5
A simple, sensitive and selective chemiluminescence (CL) method was developed for the determination of cysteine. This method is based on that the weak CL of cysteine oxidized with cerium (IV) can be greatly enhanced by quinine. The calibration curve was linear over the range 3.5×10−9–3.5×10−6 M with a detection limit of 2.5×10−9 M (S/N=3). The RSD was found to be 8.4% by 10 replicate determinations of 2.9×10−8 M cysteine. Due to high sensitivity, the proposed method can be used directly to determine the total concentration of cysteine in human serum through simply diluting the sample for a thousand fold. The obtained result was in agreement with that given by amino acid autoanalyzer. The present method does not require any separation, showing a simpler analytical characteristic. The mechanism of the CL reaction was also discussed.
Co-reporter:Liying Cui, Wen Shi, Jingxia Wang, Yanlin Song, Huimin Ma and Lei Jiang
Analytical Methods (2009-Present) 2010 - vol. 2(Issue 5) pp:NaN450-450
Publication Date(Web):2010/04/13
DOI:10.1039/C0AY00154F
The photonic crystal (PC)-based light-amplification method has been demonstrated for Hg2+ detection. A Hg2+ detection limit of ca. 10 nM was achieved via the amplification effect of a blue band edge of the PC film.
Co-reporter:Jin Zhou and Huimin Ma
Chemical Science (2010-Present) 2016 - vol. 7(Issue 10) pp:NaN6575-6575
Publication Date(Web):2016/09/02
DOI:10.1039/C6SC90059C
Correction for ‘Design principles of spectroscopic probes for biological applications’ by Jin Zhou et al., Chem. Sci., 2016, DOI: 10.1039/c6sc02500e.
Co-reporter:Xinyuan He, Lihong Li, Yu Fang, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Science (2010-Present) 2017 - vol. 8(Issue 5) pp:
Publication Date(Web):
DOI:10.1039/C6SC05712H
Co-reporter:Xiaofeng Wu, Xiaohua Li, Hongyu Li, Wen Shi and Huimin Ma
Chemical Communications 2017 - vol. 53(Issue 16) pp:NaN2446-2446
Publication Date(Web):2017/01/24
DOI:10.1039/C6CC09679D
A resorufin-based highly sensitive and selective fluorescence off–on probe with a new recognition moiety for tyrosinase is developed, and applied to detect and image endogenous tyrosinase activity in different living cells.
Co-reporter:Yu Fang, Wei Chen, Wen Shi, Hongyu Li, Ming Xian and Huimin Ma
Chemical Communications 2017 - vol. 53(Issue 62) pp:NaN8762-8762
Publication Date(Web):2017/07/14
DOI:10.1039/C7CC04093H
A new hemicyanine-based near-infrared fluorescence off–on probe with phenyl 2-(benzoylthio)benzoate as the recognition moiety to trap hydrogen polysulfides (H2Sn, n > 1) is developed, and is used for the sensitive imaging of H2Sn in cells and mice in vivo.
Co-reporter:Jin Zhou and Huimin Ma
Chemical Science (2010-Present) 2016 - vol. 7(Issue 10) pp:NaN6315-6315
Publication Date(Web):2016/07/11
DOI:10.1039/C6SC02500E
Spectroscopic (chromogenic, fluorescent, or chemiluminescent) probes have been widely used in many fields due to their high sensitivity and unrivaled spatiotemporal resolution. This area is an old one but always full of activity, because the rapid development of science and technology requires not only new probes for specific purposes (e.g., subcellular imaging) but also the update of current probes with more satisfactory properties. Based on our experiences and including existing knowledge, in this mini-review we briefly discuss the design strategies, response modes, and bioapplications of small molecular spectroscopic probes, in particular their advantages and disadvantages as well as possible research trends, which may be helpful to those who are interested in this continually growing research area.
Co-reporter:Xinyuan He, Xiaofeng Wu, Wen Shi and Huimin Ma
Chemical Communications 2016 - vol. 52(Issue 60) pp:NaN9413-9413
Publication Date(Web):2016/06/23
DOI:10.1039/C6CC04628B
A specific fluorescent probe, designed by a substitution-rearrangement mechanism, can discriminate cysteine from other thiols. Using this probe, N-acetylcysteine is revealed to be superior to cysteine to replenish intracellular cysteine in cells.
Co-reporter:Xinghui Gao, Xiaohua Li, Lihong Li, Jin Zhou and Huimin Ma
Chemical Communications 2015 - vol. 51(Issue 45) pp:NaN9390-9390
Publication Date(Web):2015/05/01
DOI:10.1039/C5CC02788H
A simple and stable fluorescent off–on probe for discrimination of cysteine (Cys) from glutathione (GSH) has been developed by combining resorufin with 7-nitrobenzofurazan. The probe, displaying distinct emission patterns for Cys and GSH at just one excitation wavelength, can be used for simultaneous determination of Cys and GSH in human plasma.
Co-reporter:Yanchao Song, Zhe Wang, Lihong Li, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2014 - vol. 50(Issue 99) pp:NaN15698-15698
Publication Date(Web):2014/10/24
DOI:10.1039/C4CC07565J
Gold nanoparticles are functionalized as a nanoprobe with cresyl violet and porphyrin via hyaluronic acid. The nanoprobe becomes highly fluorescent in the presence of hyaluronidase or under ultraviolet irradiation, and can be used to target cancer cells via the overexpressed CD44 receptor for fluorescence imaging and phototherapy.
Co-reporter:Qiongqiong Wan, Yanchao Song, Zhao Li, Xinghui Gao and Huimin Ma
Chemical Communications 2013 - vol. 49(Issue 5) pp:NaN504-504
Publication Date(Web):2012/11/20
DOI:10.1039/C2CC37725J
A new cresyl violet-based ratiometric fluorescence probe is developed and applied to fluorescence imaging of H2S in living cells and zebrafish in vivo.
Co-reporter:Zhao Li, Xinghui Gao, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2013 - vol. 49(Issue 52) pp:NaN5861-5861
Publication Date(Web):2013/05/14
DOI:10.1039/C3CC42610F
A new spectroscopic off–on probe, 7-((5-nitrothiophen-2-yl)methoxy)-3H-phenoxazin-3-one, is developed and applied to real-time detection of nitroreductase produced by Escherichia coli.
Co-reporter:Xiaohua Li, Wen Shi, Suming Chen, Jia Jia, Huimin Ma and Otto S. Wolfbeis
Chemical Communications 2010 - vol. 46(Issue 15) pp:NaN2562-2562
Publication Date(Web):2010/03/11
DOI:10.1039/C001225D
A new cyanine-based near-infrared fluorescent probe has been developed for monitoring tyrosinase activity.
Co-reporter:Wei Chen, Zhao Li, Wen Shi and Huimin Ma
Chemical Communications 2012 - vol. 48(Issue 22) pp:NaN2811-2811
Publication Date(Web):2012/01/18
DOI:10.1039/C2CC17768D
A new resorufin-based probe is developed, which exhibits a rapid and sensitive color and a fluorescence off–on response to benzoyl peroxide (BPO) in aqueous media containing 10% ethanol via deboronation. The probe has been applied to the simple detection of BPO in real samples such as wheat flour and antimicrobial agent.
Co-reporter:Wen Shi and Huimin Ma
Chemical Communications 2012 - vol. 48(Issue 70) pp:NaN8744-8744
Publication Date(Web):2012/06/21
DOI:10.1039/C2CC33366J
Spectroscopic probes have been extensively investigated and used widely in many fields because of their powerful ability to improve analytical sensitivity, and to offer greater temporal and spatial resolution (in some cases a molecule event may be visualized by the naked eye). So far, different photophysical mechanisms, such as charge transfer, photo-induced electron transfer and fluorescent resonance energy transfer, have been employed to develop various spectroscopic probes with superior properties. However, these photophysical mechanisms depend on the energy levels of molecular orbitals, which are usually difficult to accurately determine. This would lead to the poor prediction of analytical performance of the designed probe. Instead, the change of π-conjugated systems induced by chemical reactions is often accompanied by a distinct alteration in spectroscopic signal, which is more predictable and is of high signal/background ratio. This mechanism can serve as an effective measure for developing excellent spectroscopic probes, but to our knowledge, has not been systematically summarized. In this feature article, we review the development of spectroscopic probes with changeable π-conjugated systems, which is catalogued according to the fluorochromes: fluorescein, rhodamine, spiropyran, squaraine, coumarin, cyanine, etc. Two main strategies for constructing these spectroscopic probes, including ring-closing reaction and nucleophilic addition reaction, are summarized, and the merits and limitations of the probes are discussed.
Co-reporter:Duan Feng, Yangyang Zhang, Tingting Feng, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2011 - vol. 47(Issue 38) pp:NaN10682-10682
Publication Date(Web):2011/09/02
DOI:10.1039/C1CC13975D
A graphene oxide–peptide based fluorescence sensor has been developed for matrix metalloproteinase 2 (MMP2), and its applicability has been demonstrated by monitoring the concentration of MMP2 secreted by HeLa cells, revealing that HeLa cells with a density of 5.48 × 105cells per mL can produce 22 nM in cell culture media in 24 h.
Co-reporter:Chengdong Sun, Wen Shi, Yanchao Song, Wei Chen and Huimin Ma
Chemical Communications 2011 - vol. 47(Issue 30) pp:NaN8640-8640
Publication Date(Web):2011/07/01
DOI:10.1039/C1CC12174J
A new strategy that utilizes the interaction between NO and a selenide is reported for fluorescence detection of NO, in which rhodamine B selenolactone serves as a model selenide.
Co-reporter:Wen Shi and Huimin Ma
Chemical Communications 2008(Issue 16) pp:NaN1858-1858
Publication Date(Web):2008/02/27
DOI:10.1039/B717718F
Rhodamine B thiolactone is developed as a simple chemosensor towards Hg2+ in neutral aqueous solution with high selectivity.
Co-reporter:Qiuyu Gong, Lihong Li, Xiaofeng Wu and Huimin Ma
Chemical Science (2010-Present) 2016 - vol. 7(Issue 7) pp:
Publication Date(Web):
DOI:10.1039/C6SC00951D
Co-reporter:Qiuyu Gong, Wen Shi, Lihong Li and Huimin Ma
Chemical Science (2010-Present) 2016 - vol. 7(Issue 1) pp:
Publication Date(Web):
DOI:10.1039/C5SC03600C
Co-reporter:Jin Zhou, Lihong Li, Wen Shi, Xinghui Gao, Xiaohua Li and Huimin Ma
Chemical Science (2010-Present) 2015 - vol. 6(Issue 8) pp:NaN4888-4888
Publication Date(Web):2015/06/01
DOI:10.1039/C5SC01562F
Macrophages, important cells of the innate immune system, can produce abundant HOCl in the cytoplasm to fight against bacteria. Recent studies suggest that mitochondria in macrophages play a role in antibacterial responses. During bacterial infection, however, it is uncertain whether HOCl is present in the mitochondria, mainly because of the lack of a suitable research method. Herein, by developing a new mitochondrial-targeting fluorescent HOCl probe, combined with confocal fluorescence imaging, we show for the first time that HOCl can appear in the mitochondria of macrophages (Raw264.7 cells) during bacterial infection, as confirmed with non-phagocytic cells and inhibitors as control experiments. Moreover, the developed probe exhibits an accurate mitochondrial-targeting ability, a fast response, and high selectivity and sensitivity (detection limit 9 nM), and is thus expected to be employed for further revealing the biological function of subcellular mitochondria.
Co-reporter:Yanchao Song, Wen Shi, Wei Chen, Xiaohua Li and Huimin Ma
Journal of Materials Chemistry A 2012 - vol. 22(Issue 25) pp:NaN12573-12573
Publication Date(Web):2012/04/30
DOI:10.1039/C2JM31582C
In this work, an efficient approach for targeting and detecting cancer cells has been developed through the design of the assembly of fluorescent carbon nanodots and folic acid (C-dots–FA), which is endocytosible by the overexpressed folate receptor (FR) molecule. The fluorescent C-dots were prepared by a facile microwave pyrolysis method, but their surfaces were passivated with 4,7,10-trioxa-1,13-tridecanediamine, so that active amino groups could be engineered for the further conjugation with FA. The uptake of the designed C-dots–FA by HeLa cancer cells, as revealed by confocal laser scanning microscopy, is via receptor-mediated endocytosis, which is further confirmed by competition experiments as well as a comparative study with FR-negative MCF-7 cells. The proposed method shows excellent biocompatibility, and, most notably, its applicability to discriminating FR-positive cancer cells from normal cells has been successfully demonstrated by culturing and analyzing the first model cell mixture of NIH-3T3 and HeLa cells, which makes it of great potential for cancer diagnosis studies.
Co-reporter:Duan Feng, Yangyang Zhang, Wen Shi, Xiaohua Li and Huimin Ma
Chemical Communications 2010 - vol. 46(Issue 48) pp:NaN9205-9205
Publication Date(Web):2010/10/28
DOI:10.1039/C0CC02703K
A new method with high simplicity, rapidity and sensitivity has been developed for visual detection of phosgene based on the distinct color change of cysteine-modified gold nanoparticles.
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![Aspartic acid, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/42900/42808-07-1_b.png)
![L-gamma-glutamyl-N-[S-(7-nitro-2,1,3-benzoxadiazol-4-yl)-L-cysteinyl]glycine](http://img.cochemist.com/ccimg/35900/35841-75-9.png)
![L-gamma-glutamyl-N-[S-(7-nitro-2,1,3-benzoxadiazol-4-yl)-L-cysteinyl]glycine](http://img.cochemist.com/ccimg/35900/35841-75-9_b.png)
![L-Lysine, N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/28300/28217-24-5.png)
![L-Lysine, N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/28300/28217-24-5_b.png)
![L-Arginine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/28300/28217-22-3.png)
![L-Arginine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/28300/28217-22-3_b.png)
![L-Tryptophan,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/19500/19461-29-1.png)
![L-Tryptophan,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/19500/19461-29-1_b.png)
![Tryptophan, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/17100/17039-57-5.png)
![Tryptophan, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/17100/17039-57-5_b.png)
![N-[[5-(dimethylamino)-1-naphthyl]sulphonyl]-L-histidine](http://img.cochemist.com/ccimg/7300/7293-13-2.png)
![N-[[5-(dimethylamino)-1-naphthyl]sulphonyl]-L-histidine](http://img.cochemist.com/ccimg/7300/7293-13-2_b.png)
![L-Proline,1-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1300/1239-94-7.png)
![L-Proline,1-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1300/1239-94-7_b.png)
![L-Glutamic acid, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1101-68-4.png)
![L-Glutamic acid, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1101-68-4_b.png)
![L-Glutamine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1101-67-3.png)
![L-Glutamine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1101-67-3_b.png)
![Benzo[a]phenoxazin-7-ium,5-amino-9-(dimethylamino)-10-methyl-, chloride (1:1)](http://img.cochemist.com/ccimg/18500/18472-89-4.png)
![Benzo[a]phenoxazin-7-ium,5-amino-9-(dimethylamino)-10-methyl-, chloride (1:1)](http://img.cochemist.com/ccimg/18500/18472-89-4_b.png)
![2-Cyclopenten-1-one, 2-[hydroxy(4-nitrophenyl)methyl]-](http://img.cochemist.com/ccimg/203200/203111-48-2.png)
![2-Cyclopenten-1-one, 2-[hydroxy(4-nitrophenyl)methyl]-](http://img.cochemist.com/ccimg/203200/203111-48-2_b.png)
![5H-Benzo[a]phenoxazin-5-one, 9-(diethylamino)-2-hydroxy-](http://img.cochemist.com/ccimg/188800/188712-75-6.png)
![5H-Benzo[a]phenoxazin-5-one, 9-(diethylamino)-2-hydroxy-](http://img.cochemist.com/ccimg/188800/188712-75-6_b.png)
![D-Tyrosine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/109600/109527-34-6.png)
![D-Tyrosine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/109600/109527-34-6_b.png)
![D-Aspartic acid, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/95500/95465-25-1.png)
![D-Aspartic acid, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/95500/95465-25-1_b.png)
![Threonine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-11-9.png)
![Threonine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-11-9_b.png)
![D-Methionine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-10-8.png)
![D-Methionine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-10-8_b.png)
![D-Serine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-09-5.png)
![D-Serine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-09-5_b.png)
![D-Threonine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-08-4.png)
![D-Threonine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/77500/77481-08-4_b.png)
![D-ISOLEUCINE, N-[[5-(DIMETHYLAMINO)-1-NAPHTHALENYL]SULFONYL]-](http://img.cochemist.com/ccimg/77500/77426-59-6.png)
![D-ISOLEUCINE, N-[[5-(DIMETHYLAMINO)-1-NAPHTHALENYL]SULFONYL]-](http://img.cochemist.com/ccimg/77500/77426-59-6_b.png)
![L-SERINE, N-[N-[N-(N-L-TYROSYLGLYCYL)GLYCYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/69500/69473-00-3.png)
![L-SERINE, N-[N-[N-(N-L-TYROSYLGLYCYL)GLYCYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/69500/69473-00-3_b.png)
![L-PHENYLALANINE, N-[N-[N-(N-L-TYROSYLGLYCYL)GLYCYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/68900/68800-32-8.png)
![L-PHENYLALANINE, N-[N-[N-(N-L-TYROSYLGLYCYL)GLYCYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/68900/68800-32-8_b.png)
![Glycine, N-[N-[N-(N-L-tyrosylglycyl)glycyl]-L-phenylalanyl]-](http://img.cochemist.com/ccimg/61100/61064-76-4.png)
![Glycine, N-[N-[N-(N-L-tyrosylglycyl)glycyl]-L-phenylalanyl]-](http://img.cochemist.com/ccimg/61100/61064-76-4_b.png)
![L-LEUCINE, N-[N-[N-(N-L-TYROSYLGLYCYL)-L-ALANYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/60300/60254-87-7.png)
![L-LEUCINE, N-[N-[N-(N-L-TYROSYLGLYCYL)-L-ALANYL]-L-PHENYLALANYL]-](http://img.cochemist.com/ccimg/60300/60254-87-7_b.png)
![D-Alanine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/56200/56176-32-0.png)
![D-Alanine, N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/56200/56176-32-0_b.png)
![1-[4-(2-HYDROXY-4-METHOXYBENZOYL)-1-PIPERIDINYL]ETHANONE](http://img.cochemist.com/ccimg/56200/56176-31-9.png)
![1-[4-(2-HYDROXY-4-METHOXYBENZOYL)-1-PIPERIDINYL]ETHANONE](http://img.cochemist.com/ccimg/56200/56176-31-9_b.png)
![N-[[5-(dimethylamino)-1-naphthyl]sulphonyl]-L-tyrosine](http://img.cochemist.com/ccimg/52200/52107-47-8.png)
![N-[[5-(dimethylamino)-1-naphthyl]sulphonyl]-L-tyrosine](http://img.cochemist.com/ccimg/52200/52107-47-8_b.png)
![Spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one,3',6'-bis(ethylamino)-2',7'-dimethyl-](http://img.cochemist.com/ccimg/41400/41382-37-0.png)
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![L-Alanine,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/35100/35021-10-4.png)
![L-Alanine,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/35100/35021-10-4_b.png)
![L-Methionine,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/17100/17039-58-6.png)
![L-Methionine,N-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/17100/17039-58-6_b.png)
![5H-Benzo[a]phenoxazin-5-one,9-(diethylamino)-](http://img.cochemist.com/ccimg/7400/7385-67-3.png)
![5H-Benzo[a]phenoxazin-5-one,9-(diethylamino)-](http://img.cochemist.com/ccimg/7400/7385-67-3_b.png)
![3',6'-Dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one](http://img.cochemist.com/ccimg/2400/2321-07-5.png)
![3',6'-Dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one](http://img.cochemist.com/ccimg/2400/2321-07-5_b.png)
![N-{[5-(dimethylamino)naphthalen-1-yl]sulfonyl}aspartic acid](http://img.cochemist.com/ccimg/1200/1100-24-9.png)
![N-{[5-(dimethylamino)naphthalen-1-yl]sulfonyl}aspartic acid](http://img.cochemist.com/ccimg/1200/1100-24-9_b.png)
![L-Asparagine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1100-23-8.png)
![L-Asparagine,N2-[[5-(dimethylamino)-1-naphthalenyl]sulfonyl]-](http://img.cochemist.com/ccimg/1200/1100-23-8_b.png)
