Journal articles: 'Fluorescents probes'

1

Zhang, Yujin, and Wei Hu. "Sensing Performance and Efficiency of Two Energy Transfer-Based Two-Photon Fluorescent Probes for pH." Sensors 18, no. 12 (December 13, 2018): 4407. http://dx.doi.org/10.3390/s18124407.

Full text

Abstract:

The design and synthesis of fluorescent probes for monitoring pH values inside living cells have attracted great attention, due to the important role pH plays in many biological processes. In this study, the optical properties of two different two-photon fluorescent probes for pH are studied. The ratiometric sensing of the probes are theoretically illustrated. Meanwhile, the recognitional mechanisms of the probes are investigated, which shows the energy transfer process when react with H+. Specially, the calculated results demonstrate that Probe1 possesses a higher energy transfer efficiency and a larger two-photon absorption cross-section than Probe2, indicating it to be a preferable pH fluorescent probe. Therefore, the influence of connection between the donor and the acceptor on the sensing performances of the probe is demonstrated. Our results help to understand the experimental observations and provide a theoretical basis to synthesize efficient two-photon fluorescent probes for monitoring pH changes.

APA, Harvard, Vancouver, ISO, and other styles

2

Yan, Yuling, M. Emma Marriott, Chutima Petchprayoon, and Gerard Marriott. "Optical switch probes and optical lock-in detection (OLID) imaging microscopy: high-contrast fluorescence imaging within living systems." Biochemical Journal 433, no. 3 (January 14, 2011): 411–22. http://dx.doi.org/10.1042/bj20100992.

Full text

Abstract:

Few to single molecule imaging of fluorescent probe molecules can provide information on the distribution, dynamics, interactions and activity of specific fluorescently tagged proteins during cellular processes. Unfortunately, these imaging studies are made challenging in living cells because of fluorescence signals from endogenous cofactors. Moreover, related background signals within multi-cell systems and intact tissue are even higher and reduce signal contrast even for ensemble populations of probe molecules. High-contrast optical imaging within high-background environments will therefore require new ideas on the design of fluorescence probes, and the way their fluorescence signals are generated and analysed to form an image. To this end, in the present review we describe recent studies on a new family of fluorescent probe called optical switches, with descriptions of the mechanisms that underlie their ability to undergo rapid and reversible transitions between two distinct states. Optical manipulation of the fluorescent and non-fluorescent states of an optical switch probe generates a modulated fluorescence signal that can be isolated from a larger unmodulated background by using OLID (optical lock-in detection) techniques. The present review concludes with a discussion on select applications of synthetic and genetically encoded optical switch probes and OLID microscopy for high-contrast imaging of specific proteins and membrane structures within living systems.

APA, Harvard, Vancouver, ISO, and other styles

3

Mei, Qunbo, Ruqiang Tian, Yujie Shi, Qingfang Hua, Chen Chen, and Bihai Tong. "A series of selective and sensitive fluorescent sensors based on a thiophen-2-yl-benzothiazole unit for Hg2+." New Journal of Chemistry 40, no. 3 (2016): 2333–42. http://dx.doi.org/10.1039/c5nj02259b.

Full text

Abstract:

Different types of fluorescent probes for Hg²⁺ based on the 5-thiophen-2-yl-benzothiazole derivatives (TBT, CTBT, DTBT and NTBT) were realized by changing the subsituents, including the fluorescence quenching probe, the fluorescence enhancement probe and the ratiometric fluorescent probe.

APA, Harvard, Vancouver, ISO, and other styles

4

Zhou, Dan, Lei Zhou, Xiaoyan Hu, Yan Hu, and Ping Hu. "Detection and Imaging Application of miRNA in Cells and Living Organisms with Nano-Fluorescent Probes Made by Novel Synthesis Materials." Science of Advanced Materials 11, no. 12 (December 1, 2019): 1806–15. http://dx.doi.org/10.1166/sam.2019.3724.

Full text

Abstract:

As a kind of rare earth fluorescent material, the rare earth upconversion nanomaterial can be applied in various fields such as biological detection and imaging, solar cells, and safe positioning, which has attracted wide concerns. In this study, the novel material is applied to the preparation of biological nano-fluorescent probes. Due to its broad UV absorption spectrum, cobalt oxyhydroxide is selected and used as a quencher for upconversion nanomaterials. Once the cobalt oxyhydroxide is placed on upconversion nanomaterials, the surface reaction can effectively remove the fluorescence reaction of the upconversion nanomaterial. In terms of the molecular miRNA tests for cells and living organisms, the nano-fluorescent probe can reduce the fluorescence intensity of miRNA, while the control group can finish the normal fluorescence reaction. The designed fluorescent probe can adjust the contents of cobalt oxyhydroxides and cells to regulate the fluorescence intensity. In terms of the miRNA sensitivity tests, the fluorescence intensity detected by the nano-fluorescent probe is significantly lower than that in the control group, which can be observed through the fluorescence recovery tests of the chemical system. After the addition of miRNA obtained from cells or living organisms, the fluorescent probe has apparently changed the fluorescence intensity of miRNA in cells/living organisms. Also, the detection range of miRNA is effectively expanded, i.e., the different concentrations of miRNA can be detected by adjusting the ratio of the components of the fluorescent probes, which indicates the excellent sensitivity of the fluorescent probe in detecting miRNA in cells and living organisms. In terms of the miRNA tests for cells, different degrees of cancer cells are selected. The fluorescent probe can discriminate the concentration of cancer cells according to fluorescence imaging of cancer cells, thereby further explaining that the fluorescent probe has high-sensitivity in bio-detection.

APA, Harvard, Vancouver, ISO, and other styles

5

Le, X. Chris, Victor Pavski, and Hailin Wang. "2002 W.A.E. McBryde Award Lecture Affinity recognition, capillary electrophoresis, and laser-induced fluorescence polarization for ultrasensitive bioanalysis." Canadian Journal of Chemistry 83, no. 3 (March 1, 2005): 185–94. http://dx.doi.org/10.1139/v04-175.

Full text

Abstract:

The combination of affinity recognition, capillary electrophoresis (CE), laser-induced fluorescence (LIF), and fluorescence polarization for the ultrasensitive determination of compounds of biological interest is described. Competitive immunoassays using CELIF eliminate the need for fluorescently labeling trace analytes of interest and are particularly useful for determination of small molecules, such as cyclosporine, gentamicin, vancomycin, and digoxin. Fluorescence polarization allows for differentiation of the antibody-bound from the unbound small molecules. Noncompetitive affinity CELIF assays are shown to be highly effective in the determination of biomarkers for DNA damage and HIV-1 infection. An antibody (or aptamer) is used as a fluorescent probe to bind with a target DNA adduct (or the reverse transcriptase of the HIV-1 virus), with the fluorescent reaction products being separated by CE and detected by LIF. Aptamers are attractive affinity probes for protein analysis because of high affinity, high specificity, and the potential for a wide range of target proteins. Fluorescence polarization provides unique information for studying molecular interactions. Innovative integrations of these technologies will have broad applications ranging from cancer research, to biomedical diagnosis, to pharmaceutical and environmental analyses.Key words: capillary electrophoresis, laser-induced fluorescence, fluorescence polarization, immunoassay, affinity probes, antibodies, aptamers, DNA damage, toxins, therapeutic drugs.

APA, Harvard, Vancouver, ISO, and other styles

6

Qin, Qiu Yan, Yi Ping Qian, Zi Yu Wang, and Xiao Lin Fan. "Design and Synthesis of Fluorescent Betahistine Conjugates with Unique Imaging Property." Advanced Materials Research 557-559 (July 2012): 712–15. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.712.

Full text

Abstract:

Labeling cardiovascular drugs probes with a fluorescent tag is an alternative method of measuring drugs activities and distributions in vivo, and further using of advanced tools to diagnose or detect cardiovascular diseases. Using this approach, a fluorescent probe (betahistine-Flu, 1) of Betahistine-based was synthesized and characterized by 1H NMR, 13C NMR and LC-MS, and its UV-Vis absorption spectral and fluorescence spectral, and fluorescence imaging in cell model were investigated. It was found that the fluorescent probe display strong green fluorescence, and have good optical effect in cell. This study reveals a good and interesting results of betahistine-directed fluorescent probe, and its may be a possible candidate for cardiovascular disease diagnosis and analysis in vivo.

APA, Harvard, Vancouver, ISO, and other styles

7

Kircher, Moritz F., Lee Josephson, and Ralph Weissleder. "Ratio Imaging of Enzyme Activity Using Dual Wavelength Optical Reporters." Molecular Imaging 1, no. 2 (April 1, 2002): 153535002002011. http://dx.doi.org/10.1162/15353500200201124.

Full text

Abstract:

The design of near-infrared fluorescent (NIRF) probes that are activated by specific proteases has, for the first time, allowed enzyme activity to be imaged in vivo. In the current study, we report on a method of imaging enzyme activity using two fluorescent probes that, together, provide improved quantitation of enzymatic activity. The method employs two chemically similar probes that differ in their degradability by cathepsin B. One probe consists of the NIRF dye Cy5.5 attached to a particulate carrier, a crosslinked iron oxide nanoparticle (CLIO), through cathepsin B cleavable l-arginyl peptides. A second probe consists of Cy3.5 attached to a CLIO through proteolytically resistant d-arginyl peptides. Using mixtures of the two probes, we have shown that the ratio of Cy5.5 to Cy3.5 fluorescence can be used to determine levels of cathepsin B in the environment of nanoparticles with macrophages in suspension. After intravenous injection, tissue fluorescence from the nondegradable Cy3.5–d-arginyl probe reflected nanoparticle accumulation, while fluorescence of the Cy5.5–l-arginyl probe was dependent on both accumulation and activation by cathepsin B. Dual wavelength ratio imaging can be used for the quantitative imaging of a variety of enzymes in clinically important settings, while the magnetic properties of the probes allow their detection by MR imaging.

APA, Harvard, Vancouver, ISO, and other styles

8

Song, Meng Meng, Wen Juan Guo, Zhao Dai, Kai Li Qiu, and Jun Fu Wei. "Fluorescent DNA Probes Based on Quantum Dots and Core/Shell Quantum Dots." Applied Mechanics and Materials 372 (August 2013): 115–18. http://dx.doi.org/10.4028/www.scientific.net/amm.372.115.

Full text

Abstract:

Fluorescent DNA probes based on the fluorescence resonance energy transfer (FRET) were presented in this paper when AuNPs were as the energy acceptors and CdTe quantum dots and CdTe/SiO2 core/shell nanoparticles were as the energy acceptors, respectively. The DNA probes were prepared when energy donors and acceptors were conjugated with two single-stranded complementary oligonucleotides and hybridized with each other and the fluorescent intensity of probes could be decreased. The quenching efficiency of DNA probe was about 67 % when CdTe QDs were as the energy donors, while that of DNA probe was about 75 % when CdTe/SiO2 fluorescent core/shell nanoparticles were as the energy acceptors, which indicated that CdTe/SiO2 core/shell nanoparticles were suitable donors compared with CdTe QDs in DNA probe field.

APA, Harvard, Vancouver, ISO, and other styles

9

Wagner, Brian D., Amy E. Arnold, Spencer T. Gallant, Carmen R. Grinton, Julia K. Locke, Natasha D. Mills, Carrie A. Snow, Timara B. Uhlig, and Christen N. Vessey. "The polarity sensitivity factor of some fluorescent probe molecules used for studying supramolecular systems and other heterogeneous environments." Canadian Journal of Chemistry 96, no. 7 (July 2018): 629–35. http://dx.doi.org/10.1139/cjc-2017-0727.

Full text

Abstract:

Fluorescence spectroscopy provides an excellent technique for investigating heterogeneous systems, due to its high sensitivity and the large effect of the local environment on molecular emission. In addition, the use of polarity-sensitive fluorescent probes as guests in supramolecular host–guest inclusion complexes can be exploited in fluorescent sensors. This paper identifies, tabulates, and quantifies a series of useful polarity-sensitive fluorescent probes, with a wide range of polarity-dependent fluorescence responses. The degree of polarity sensitivity is quantified using the polarity sensitivity factor (PSF), developed in our laboratory. In most cases, such polarity-sensitive probes show increased emission as the local polarity is decreased (PSF > 1); 10 such probes are described. However, less commonly, “reverse polarity dependence” can occur in which probe emission decreases with decreasing polarity (PSF < 1); four such probes are described. The mechanism for the observed polarity-induced fluorescence changes will also be discussed in selected representative cases. The purpose of this paper is to present details on a broad arsenal of polarity-sensitive fluorescence probes with varying properties, with potentially useful applications in the study of heterogeneous systems, including inclusion phenomena, and in practical applications such as fluorescent sensors, which will be useful to researchers studying supramolecular and other heterogeneous systems using fluorescence spectroscopy.

APA, Harvard, Vancouver, ISO, and other styles

10

Park, Sun Young, Eugeine Jung, Jong Seung Kim, Sung-Gil Chi, and Min Hee Lee. "Cancer-Specific hNQO1-Responsive Biocompatible Naphthalimides Providing a Rapid Fluorescent Turn-On with an Enhanced Enzyme Affinity." Sensors 20, no. 1 (December 20, 2019): 53. http://dx.doi.org/10.3390/s20010053.

Full text

Abstract:

Human NAD(P)H:quinone oxidoreductase 1 (hNQO1) is overexpressed in cancer cells and associated with the drug resistance factor of cancer. The objective of this work is the development of fluorescent probes for the efficient detection of hNQO1 activity in cancer cells, which can be employed for the cancer diagnosis and therapeutic agent development. Herein, we report naphthalimide-based fluorescent probes 1 and 2 that can detect hNQO1. For hNQO1 activity, the probes showed a significant fluorescence increase at 540 nm. In addition, probe 1, the naphthalimide containing a triphenylphosphonium salt, showed an enhanced enzyme efficiency and rapid detection under a physiological condition. The detection ability of probe 1 was superior to that of other previously reported probes. Moreover, probe 1 was less cytotoxic during the cancer cell imaging and readily provided a strong fluorescence in hNQO1-overexpressed cancer cells (A549). We proposed that probe 1 can be used to detect hNQO1 expression in live cells and it will be applied to develop the diagnosis and customized treatment of hNQO1-related disease.

APA, Harvard, Vancouver, ISO, and other styles

11

Kubota, Kengo, Akiyoshi Ohashi, Hiroyuki Imachi, and Hideki Harada. "Improved In Situ Hybridization Efficiency with Locked-Nucleic-Acid-Incorporated DNA Probes." Applied and Environmental Microbiology 72, no. 8 (August 2006): 5311–17. http://dx.doi.org/10.1128/aem.03039-05.

Full text

Abstract:

ABSTRACT Low signal intensity due to poor probe hybridization efficiency is one of the major drawbacks of rRNA-targeted in situ hybridization. There are two major factors affecting the hybridization efficiency: probe accessibility and affinity to the targeted rRNA molecules. In this study, we demonstrate remarkable improvement in in situ hybridization efficiency by applying locked-nucleic-acid (LNA)-incorporated oligodeoxynucleotide probes (LNA/DNA probes) without compromising specificity. Fluorescently labeled LNA/DNA probes with two to four LNA substitutions exhibited strong fluorescence intensities equal to or greater than that of probe Eub338, although these probes did not show bright signals when they were synthesized as DNA probes; for example, the fluorescence intensity of probe Eco468 increased by 22-fold after three LNA bases were substituted for DNA bases. Dissociation profiles of the probes revealed that the dissociation temperature was directly related to the number of LNA substitutions and the fluorescence intensity. These results suggest that the introduction of LNA residues in DNA probes will be a useful approach for effectively enhancing probe hybridization efficiency.

APA, Harvard, Vancouver, ISO, and other styles

12

Marriott, Gerard, Shu Mao, Tomoyo Sakata, Jing Ran, David K. Jackson, Chutima Petchprayoon, Timothy J. Gomez, et al. "Optical lock-in detection imaging microscopy for contrast-enhanced imaging in living cells." Proceedings of the National Academy of Sciences 105, no. 46 (November 12, 2008): 17789–94. http://dx.doi.org/10.1073/pnas.0808882105.

Full text

Abstract:

One of the limitations on imaging fluorescent proteins within living cells is that they are usually present in small numbers and need to be detected over a large background. We have developed the means to isolate specific fluorescence signals from background by using lock-in detection of the modulated fluorescence of a class of optical probe termed “optical switches.” This optical lock-in detection (OLID) approach involves modulating the fluorescence emission of the probe through deterministic, optical control of its fluorescent and nonfluorescent states, and subsequently applying a lock-in detection method to isolate the modulated signal of interest from nonmodulated background signals. Cross-correlation analysis provides a measure of correlation between the total fluorescence emission within single pixels of an image detected over several cycles of optical switching and a reference waveform detected within the same image over the same switching cycles. This approach to imaging provides a means to selectively detect the emission from optical switch probes among a larger population of conventional fluorescent probes and is compatible with conventional microscopes. OLID using nitrospirobenzopyran-based probes and the genetically encoded Dronpa fluorescent protein are shown to generate high-contrast images of specific structures and proteins in labeled cells in cultured and explanted neurons and in live Xenopus embryos and zebrafish larvae.

APA, Harvard, Vancouver, ISO, and other styles

13

Caselli, Monica. "Porphyrin-based electrostatically self-assembled multilayers as fluorescent probes for mercury(ii) ions: a study of the adsorption kinetics of metal ions on ultrathin films for sensing applications." RSC Advances 5, no. 2 (2015): 1350–58. http://dx.doi.org/10.1039/c4ra09814e.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Sun, Yulong, and Avi Chakrabartty. "Cost-effective elimination of lipofuscin fluorescence from formalin-fixed brain tissue by white phosphor light emitting diode array." Biochemistry and Cell Biology 94, no. 6 (December 2016): 545–50. http://dx.doi.org/10.1139/bcb-2016-0125.

Full text

Abstract:

Autofluorescence of aldehyde-fixed tissues greatly hinders fluorescence microscopy. In particular, lipofuscin, an autofluorescent component of aged brain tissue, complicates fluorescence imaging of tissue in neurodegenerative diseases. Background and lipofuscin fluorescence can be reduced by greater than 90% through photobleaching using white phosphor light emitting diode arrays prior to treatment with fluorescent probes. We compared the effect of photobleaching versus established chemical quenchers on the quality of fluorescent staining in formalin-fixed brain tissue of frontotemporal dementia with tau-positive inclusions. Unlike chemical quenchers, which reduced fluorescent probe signals as well as background, photobleaching treatment had no effect on probe fluorescence intensity while it effectively reduced background and lipofuscin fluorescence. The advantages and versatility of photobleaching over established methods are discussed.

APA, Harvard, Vancouver, ISO, and other styles

15

Tian, Ye, Miao Li, and Ying Liu. "Detection Sensitivity Enhancement of Naphthalimide PET Fluorescent Probes by 4-Methoxy-Substitution." Molecules 25, no. 19 (September 29, 2020): 4465. http://dx.doi.org/10.3390/molecules25194465.

Full text

Abstract:

Naphthalimide photoinduced electron transfer (PET) fluorescent probes are widely used in fluorescence imaging. Thereinto, detection sensitivity is the vital parameter of PET probes. However, the modulation of detection sensitivity is yet to be reported for naphthalimide PET probes. Herein, the detection sensitivity enhancement of naphthalimide PET fluorescent probes through 4-methoxy-substitution is proposed in this work. Taking Zn2+ detection an example, 4-methoxy-naphthalimide PET probe 2-(2-(bis(pyridin-2-ylmethyl)amino)ethyl)-6-methoxy-1H-benzo[de]isoquinoline-1,3(2H)-dione (BPNM) and control PET probe 2-(2-(bis(pyridin-2-ylmethyl)amino)ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (BPN) are separately synthesized. The addition of 4-methoxy group with ability of strong electron donating to naphthalimide facilitates the construction of electronic push-pull system in the fluorophore resulting in the bathochromic shift of absorption and fluorescence emission spectra of BPNM and is further conducive to the enhancement of molar extinction coefficient ε and fluorescence quantum yield Φf of BPNM. Compared with BPN, BPNM shows lower Zn2+ detection limit in titration assays. Meanwhile, the fluorescence signal change (off-on) before and after Zn2+ addition of intracellular BPNM is more obvious and easier to control in confocal laser scanning imaging. Therefore, 4-methoxy-substitution improves the detection sensitivity of naphthalimide PET probe, which is favorable for the precise sensing of analyte, and further lays a good foundation for the synthesis of PET probe with high sensitivity.

APA, Harvard, Vancouver, ISO, and other styles

16

Ge, Feng-Yan, and Li-Gong Chen. "pH Fluorescent Probes: Chlorinated Fluoresceins." Journal of Fluorescence 18, no. 3-4 (December 21, 2007): 741–47. http://dx.doi.org/10.1007/s10895-007-0305-y.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Liu, Ying, Zhou Ding, Jingjing Zhang, Chunyuan Song, Le Zhang, and Ying Liu. "Highly Sensitive Detection of miRNA-155 Using Molecular Beacon-Functionalized Monolayer MoS2 Nanosheet Probes with Duplex-Specific Nuclease-Mediated Signal Amplification." Journal of Biomedical Nanotechnology 17, no. 6 (June 1, 2021): 1034–43. http://dx.doi.org/10.1166/jbn.2021.3096.

Full text

Abstract:

MicroRNA-155 (miRNA-155) as a characteristic myeloma-associated biomarker exhibits significant potential application in the diagnosis of multiple myeloma (MM). In this paper, a novel type of molecular beacon (MB)-functionalized monolayer MoS2 nanosheet probe was proposed as fluorescent probe for high-sensitive assays of miRNA-155that uses a duplexspecificnuclease (DSN) enzyme to amplify the fluorescence signal. The preparation and detection conditions of the fluorescent probes were optimized in some aspects, such as the concentration of MoS2 (0.80 μM) and DSN (0.2 U), and the incubation time of DSN (30 min). The probesexhibited a sensitive fluorescence response to miRNA-155 and the fluorescence signal of the assay was significantly amplified by the cleavage of DSN. The relationship between F/F0 and logC miRNA follows a linear calibration curve, and the limit of detection (LOD) of miRNA-155 in 10% human serum is calculated to be 10.96 fM based on this relationship. The good performance and fluorescence amplification effect of the fluorescent probe were confirmed by studying the recovery of miRNA-155 in 10% human serum, which was ranged from 98.32% to 106.3% with a relative standard deviation of less than 4.14%. Besides, the high expression of miRNA-155 in clinic blood of MM patients was sensitively distinguished from healthy peoples by using the proposed probes. The proposed novel fluorescent probe based on the DSN can be used to detect miRNA-155 in human serum and provide a potential, convenient and reliable tool for diagnosis of MM.

APA, Harvard, Vancouver, ISO, and other styles

18

Ward, G. E., L. H. Miller, and J. A. Dvorak. "The origin of parasitophorous vacuole membrane lipids in malaria-infected erythrocytes." Journal of Cell Science 106, no. 1 (September 1, 1993): 237–48. http://dx.doi.org/10.1242/jcs.106.1.237.

Full text

Abstract:

During invasion of an erythrocyte by a malaria merozoite, an indentation develops in the erythrocyte surface at the point of contact between the two cells. This indentation deepens as invasion progresses, until the merozoite is completely surrounded by a membrane known as the parasitophorous vacuole membrane (PVM). We incorporated fluorescent lipophilic probes and phospholipid analogs into the erythrocyte membrane, and followed the fate of these probes during PVM formation with low-light-level video fluorescence microscopy. The concentration of probe in the forming PVM was indistinguishable from the concentration of probe in the erythrocyte membrane, suggesting that the lipids of the PVM are continuous with and derived from the host cell membrane during invasion. In contrast, fluorescently labeled erythrocyte surface proteins were largely excluded from the forming PVM. These data are consistent with a model for PVM formation in which the merozoite induces a localized invagination in the erythrocyte lipid bilayer, concomitant with a localized restructuring of the host cell cytoskeleton.

APA, Harvard, Vancouver, ISO, and other styles

19

Paulson, Bjorn, Yeonhee Shin, Akimitsu Okamoto, Yeon-Mok Oh, Jun Ki Kim, and Chan-Gi Pack. "Poly(A)+ Sensing of Hybridization-Sensitive Fluorescent Oligonucleotide Probe Characterized by Fluorescence Correlation Methods." International Journal of Molecular Sciences 22, no. 12 (June 16, 2021): 6433. http://dx.doi.org/10.3390/ijms22126433.

Full text

Abstract:

Ribonucleic acid (RNA) plays an important role in many cellular processes. Thus, visualizing and quantifying the molecular dynamics of RNA directly in living cells is essential to uncovering their role in RNA metabolism. Among the wide variety of fluorescent probes available for RNA visualization, exciton-controlled hybridization-sensitive fluorescent oligonucleotide (ECHO) probes are useful because of their low fluorescence background. In this study, we apply fluorescence correlation methods to ECHO probes targeting the poly(A) tail of mRNA. In this way, we demonstrate not only the visualization but also the quantification of the interaction between the probe and the target, as well as of the change in the fluorescence brightness and the diffusion coefficient caused by the binding. In particular, the uptake of ECHO probes to detect mRNA is demonstrated in HeLa cells. These results are expected to provide new insights that help us better understand the metabolism of intracellular mRNA.

APA, Harvard, Vancouver, ISO, and other styles

20

Neuhaus, Frederik, Fabio Zobi, Gerald Brezesinski, Marta Dal Molin, Stefan Matile, and Andreas Zumbuehl. "Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface." Beilstein Journal of Organic Chemistry 13 (June 8, 2017): 1099–105. http://dx.doi.org/10.3762/bjoc.13.109.

Full text

Abstract:

It is currently not possible to directly measure the lateral pressure of a biomembrane. Mechanoresponsive fluorescent probes are an elegant solution to this problem but it requires first the establishment of a direct correlation between the membrane surface pressure and the induced color change of the probe. Here, we analyze planarizable dithienothiophene push–pull probes in a monolayer at the air/water interface using fluorescence microscopy, grazing-incidence angle X-ray diffraction, and infrared reflection–absorption spectroscopy. An increase of the lateral membrane pressure leads to a well-packed layer of the ‘flipper’ mechanophores and a clear change in hue above 18 mN/m. The fluorescent probes had no influence on the measured isotherm of the natural phospholipid DPPC suggesting that the flippers probe the lateral membrane pressure without physically changing it. This makes the flipper probes a truly useful addition to the membrane probe toolbox.

APA, Harvard, Vancouver, ISO, and other styles

21

More, Lim, Kang, Yun, Yee, and Chang. "Asymmetric and Reduced Xanthene Fluorophores: Synthesis, Photochemical Properties, and Application to Activatable Fluorescent Probes for Detection of Nitroreductase." Molecules 24, no. 17 (September 3, 2019): 3206. http://dx.doi.org/10.3390/molecules24173206.

Full text

Abstract:

Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. “Turn on” activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and prepared to reduce the high background signal of “always-on” fluorescent probes. However, the development of activity-based fluorescent probes for biological applications, using simple xanthene dyes, is hampered by their inefficient synthetic methods and the difficulty of chemical modifications. We have, thus, developed a highly efficient, versatile synthetic route to developing chemically more stable reduced xanthene fluorophores, based on fluorescein, rhodol, and rhodamine via continuous Pd-catalyzed cross-coupling. Their fluorescent nature was evaluated by monitoring fluorescence with variation in the concentration, pH, and solvent. As an application to activatable fluorescent probe, nitroreductase (NTR)-responsive fluorescent probes were also developed using the reduced xanthene fluorophores, and their fluorogenic properties were evaluated.

APA, Harvard, Vancouver, ISO, and other styles

22

Mavreas, Konstantinos F., Michael Mamais, Panagiota Papazafiri, and Thanasis Gimisis. "Glucose-Based Molecular Rotors as Fluorescent Inhibitors and Probes of Glycogen Phosphorylase." Chemistry Proceedings 3, no. 1 (November 14, 2020): 45. http://dx.doi.org/10.3390/ecsoc-24-08414.

Full text

Abstract:

In this study, (E)-2-cyano-3-(6-(dimethylamino)naphthalen-2-yl)-N-(β-d-glucopyranosyl)acrylamide, a β-d-glucopyranosyl analogue of the widely used molecular rotor julolidine, was synthesized and studied photochemically. The new compound is a fluorescent inhibitor of rabbit muscle glycogen phosphorylase with properties of a molecular rotor. Fluorescence measurements in solutions of increasing viscosity determined that the fluorescence intensity increases with the viscosity of the medium, indicating that the new compound exhibits molecular rotor characteristics. Although the compound fluoresces negligibly in an aqueous buffer solution, in the presence of increasing amounts of rabbit muscle glycogen phosphorylase, we observed an increase in fluorescence intensity, which was attributed to the formation of an inhibitor–enzyme complex. In-vitro cellular studies were also undertaken, yielding promising preliminary results for the use of the new compound as a fluorescent probe.

APA, Harvard, Vancouver, ISO, and other styles

23

Tam, Jenny, Alexander Pilozzi, Umar Mahmood, and Xudong Huang. "Simultaneous Monitoring of Multi-Enzyme Activity and Concentration in Tumor Using a Triply Labeled Fluorescent In Vivo Imaging Probe." International Journal of Molecular Sciences 21, no. 9 (April 27, 2020): 3068. http://dx.doi.org/10.3390/ijms21093068.

Full text

Abstract:

The use of fluorescent imaging probes that monitor the activity of proteases that experience an increase in expression and activity in tumors is well established. These probes can be conjugated to nanoparticles of iron oxide, creating a multimodal probe serving as both a magnetic resonance imaging (MRI) agent and an indicator of local protease activity. Previous works describe probes for cathepsin D (CatD) and metalloproteinase-2 (MMP2) protease activity grafted to cross-linked iron oxide nanoparticles (CLIO). Herein, we have synthesized a triply labeled fluorescent iron oxide nanoparticle molecular imaging (MI) probe, including an AF750 substrate concentration reporter along with probes for cathepsin B (CatB) sand MMP2 protease activity. The reporter provides a baseline signal from which to compare the activity of the two proteases. The activity of the MI probe was verified through incubation with the proteases and tested in vitro using the human HT29 tumor cell line and in vivo using female nude mice injected with HT29 cells. We found the MI probe had the appropriate specificity to the activity of their respective proteases, and the reporter dye did not activate when incubated in the presence of only MMP2 and CatB. Probe fluorescent activity was confirmed in vitro, and reporter signal activation was also noted. The fluorescent activity was also visible in vivo, with injected HT29 cells exhibiting fluorescence, distinguishing them from the rest of the animal. The reporter signal was also observable in vivo, which allowed the signal intensities of the protease probes to be corrected; this is a unique feature of this MI probe design.

APA, Harvard, Vancouver, ISO, and other styles

24

Verderosa, Anthony, Rabeb Dhouib, Kathryn Fairfull-Smith, and Makrina Totsika. "Profluorescent Fluoroquinolone-Nitroxides for Investigating Antibiotic–Bacterial Interactions." Antibiotics 8, no. 1 (March 4, 2019): 19. http://dx.doi.org/10.3390/antibiotics8010019.

Full text

Abstract:

Fluorescent probes are widely used for imaging and measuring dynamic processes in living cells. Fluorescent antibiotics are valuable tools for examining antibiotic–bacterial interactions, antimicrobial resistance and elucidating antibiotic modes of action. Profluorescent nitroxides are ‘switch on’ fluorescent probes used to visualize and monitor intracellular free radical and redox processes in biological systems. Here, we have combined the inherent fluorescent and antimicrobial properties of the fluoroquinolone core structure with the fluorescence suppression capabilities of a nitroxide to produce the first example of a profluorescent fluoroquinolone-nitroxide probe. Fluoroquinolone-nitroxide (FN) 14 exhibited significant suppression of fluorescence (>36-fold), which could be restored via radical trapping (fluoroquinolone-methoxyamine 17) or reduction to the corresponding hydroxylamine 20. Importantly, FN 14 was able to enter both Gram-positive and Gram-negative bacterial cells, emitted a measurable fluorescence signal upon cell entry (switch on), and retained antibacterial activity. In conclusion, profluorescent nitroxide antibiotics offer a new powerful tool for visualizing antibiotic–bacterial interactions and researching intracellular chemical processes.

APA, Harvard, Vancouver, ISO, and other styles

25

Lai, Yau-Tsz, Yuen-Yan Chang, Ligang Hu, Ya Yang, Ailun Chao, Zhi-Yan Du, Julian A. Tanner, et al. "Rapid labeling of intracellular His-tagged proteins in living cells." Proceedings of the National Academy of Sciences 112, no. 10 (February 23, 2015): 2948–53. http://dx.doi.org/10.1073/pnas.1419598112.

Full text

Abstract:

Small molecule-based fluorescent probes have been used for real-time visualization of live cells and tracking of various cellular events with minimal perturbation on the cells being investigated. Given the wide utility of the (histidine)6-Ni2+-nitrilotriacetate (Ni-NTA) system in protein purification, there is significant interest in fluorescent Ni2+-NTA–based probes. Unfortunately, previous Ni-NTA–based probes suffer from poor membrane permeability and cannot label intracellular proteins. Here, we report the design and synthesis of, to our knowledge, the first membrane-permeable fluorescent probe Ni-NTA-AC via conjugation of NTA with fluorophore and arylazide followed by coordination with Ni2+ ions. The probe, driven by Ni2+-NTA, binds specifically to His-tags genetically fused to proteins and subsequently forms a covalent bond upon photoactivation of the arylazide, leading to a 13-fold fluorescence enhancement. The arylazide is indispensable not only for fluorescence enhancement, but also for strengthening the binding between the probe and proteins. Significantly, the Ni-NTA-AC probe can rapidly enter different types of cells, even plant tissues, to target His-tagged proteins. Using this probe, we visualized the subcellular localization of a DNA repair protein, Xeroderma pigmentosum group A (XPA122), which is known to be mainly enriched in the nucleus. We also demonstrated that the probe can image a genetically engineered His-tagged protein in plant tissues. This study thus offers a new opportunity for in situ visualization of large libraries of His-tagged proteins in various prokaryotic and eukaryotic cells.

APA, Harvard, Vancouver, ISO, and other styles

26

Wu, Huilu, Cuiping Wang, Jiawen Zhang, Yanhui Zhang, Chengyong Chen, Zaihui Yang, and Xuyang Fan. "1,8-Naphthalimide derivative-based turn-off fluorescent probe for the detection of picrate in organic aqueous media." Zeitschrift für Naturforschung B 70, no. 12 (December 1, 2015): 863–69. http://dx.doi.org/10.1515/znb-2015-0094.

Full text

Abstract:

AbstractThe synthesis of a simple fluorescent naphthalimide-based receptor N-allyl-4-iminodi(N-butylacetamide)-1,8-naphthalimide 3 was carried out as a selective picrate (Pic–) anion probe, and the detecting behavior of this probe was studied by fluorescence spectroscopy. In DMF solution, the interaction of compound 3 with different anions, including Pic–, F–, Cl–, Br–, I–, OH–, Ac–, NO3–, ClO4–, SCN–, SO32–, SO42–, H2PO4–, and HPO42–, revealed significant fluorescence quenching only with the Pic– anion. By adding the picrate anions, green-yellow fluorescence emission quenches, which is easily observed by naked eyes under a 365 nm UV light irradiation. This phenomenon is essential for producing a highly selective and sensitive fluorescent probe for picrate anions. The probe can be applied to the quantification of Pic– with a linear range covering from 4.97 × 10–6 to 6.82 × 10–5m and a detection limit of 5.8 × 10–7m. Most importantly, probe 3 has a high selectivity for picrate over competitive anions and picrate-containing analytes, which meet the selective requirements for practical application. Thus, the present results would be inspiring findings in the future design of reaction-based fluorescent turn-off probes for the environmentally relevant picrate probe.

APA, Harvard, Vancouver, ISO, and other styles

27

Galas, Ludovic, Thibault Gallavardin, Magalie Bénard, Arnaud Lehner, Damien Schapman, Alexis Lebon, Hitoshi Komuro, Patrice Lerouge, Stéphane Leleu, and Xavier Franck. "“Probe, Sample, and Instrument (PSI)”: The Hat-Trick for Fluorescence Live Cell Imaging." Chemosensors 6, no. 3 (September 13, 2018): 40. http://dx.doi.org/10.3390/chemosensors6030040.

Full text

Abstract:

Cell Imaging Platforms (CIPs) are research infrastructures offering support to a number of scientific projects including the choice of adapted fluorescent probes for live cell imaging. What to detect in what type of sample and for how long is a major issue with fluorescent probes and, for this, the “hat-trick” “Probe–Sample–Instrument” (PSI) has to be considered. We propose here to deal with key points usually discussed in CIPs including the properties of fluorescent organic probes, the modality of cell labeling, and the best equipment to obtain appropriate spectral, spatial, and temporal resolution. New strategies in organic synthesis and click chemistry for accessing probes with enhanced photophysical characteristics and targeting abilities will also be addressed. Finally, methods for image processing will be described to optimize exploitation of fluorescence signals.

APA, Harvard, Vancouver, ISO, and other styles

28

Nakai, Nori, Keisuke Sato, Tomomi Tani, Kenta Saito, Fumiya Sato, and Sumio Terada. "Genetically encoded orientation probes for F-actin for fluorescence polarization microscopy." Microscopy 68, no. 5 (July 2, 2019): 359–68. http://dx.doi.org/10.1093/jmicro/dfz022.

Full text

Abstract:

Abstract Fluorescence polarization microscopy, which can visualize both position and orientation of fluorescent molecules, is useful for analyzing architectural dynamics of proteins in vivo, especially that of cytoskeletal proteins such as actin. Fluorescent phalloidin conjugates and SiR-actin can be used as F-actin orientation probes for fluorescence polarization microscopy, but a lack of appropriate methods for their introduction to living specimens especially to tissues, embryos, and whole animals hampers their applications to image the orientation of F-actin. To solve this problem, we have developed genetically encoded F-actin orientation probes for fluorescence polarization microscopy. We rigidly connected circular permutated green fluorescent protein (GFP) to the N-terminal α-helix of actin-binding protein Lifeact or utrophin calponin homology domain (UtrCH), and normal mEGFP to the C-terminal α-helix of UtrCH. After evaluation of ensemble and single particle fluorescence polarization with the instantaneous FluoPolScope, one of the constructs turned out to be suitable for practical usage in live cell imaging. Our new, genetically encoded F-actin orientation probe, which has a similar property of an F-actin probe to conventional GFP-UtrCH, is expected to report the 3D architecture of the actin cytoskeleton with fluorescence polarization microscopy, paving the way for both the single molecular orientation imaging in cultured cells and the sub-optical resolution architectural analysis of F-actin networks analysis of F-actin in various living systems.

APA, Harvard, Vancouver, ISO, and other styles

29

Juhasz, Janos, James H. Davis, and Frances J. Sharom. "Fluorescent probe partitioning in giant unilamellar vesicles of ‘lipid raft’ mixtures." Biochemical Journal 430, no. 3 (August 27, 2010): 415–23. http://dx.doi.org/10.1042/bj20100516.

Full text

Abstract:

Direct visualization of raft-like lo (liquid-ordered) domains in model systems and cells using microscopic techniques requires fluorescence probes with known partitioning preference for one of the phases present. However, fluorescent probes may display dissimilar partitioning preferences in different lipid sys-tems and can also affect the phase behaviour of the host lipid bilayer. Therefore a detailed understanding of the behaviour of fluorescent probes in defined lipid bilayer systems with known phase behaviour is essential before they can be used for identifying domain phase states. Using giant unilamellar vesicles composed of the ternary lipid mixture DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine)/DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine)/cholesterol, for which the phase behaviour is known, we examined nine commonly used fluorescent probes using confocal fluorescence microscopy. The partitioning preference of each probe was assigned either on the basis of quantification of the domain area fractions or by using a well-characterized ld (liquid-disordered)-phase marker. Fluorescent probes were examined both individually and using dual or triple labelling approaches. Most of the probes partitioned individually into the ld phase, whereas only NAP (naphtho[2,3-a]pyrene) and NBD-DPPE [1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl] preferred the lo phase. We found that Rh-DPPE (Lissamine™ rhodamine B–1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine) increased the miscibility transition temperature, Tmix. Interestingly, the partitioning of DiIC18 (1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate) was influenced by Bodipy®-PC [2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-1-hexa-decanoyl-sn-glycero-3-phosphocholine]. The specific use of each of the fluorescent probes is determined by its photostability, partitioning preference, ability to detect lipid phase separations and induced change in Tmix. We demonstrate the importance of testing a specific fluorescent probe in a given model membrane system, rather than assuming that it labels a particular lipid phase.

APA, Harvard, Vancouver, ISO, and other styles

30

Mitchell, Felicity L., Gabriel E. Marks, Elena V. Bichenkova, Kenneth T. Douglas, and Richard A. Bryce. "Molecular probes: insights into design and analysis from computational and physical chemistry." Biochemical Society Transactions 36, no. 1 (January 22, 2008): 46–50. http://dx.doi.org/10.1042/bst0360046.

Full text

Abstract:

The application of new molecular diagnostics to probe cellular process in vivo is leading to a greater understanding of molecular cytology at a sub-nanoscale level and is opening the way to individualized medicines. We review here three distinct fluorescence-based molecular probes, HyBeacons™, split-probe exciplexes and GFP (green fluorescent protein)-based FRET (fluorescence resonance energy transfer) systems. Through this, we highlight the insights into the mechanism and design that a combined computational and experimental approach can yield.

APA, Harvard, Vancouver, ISO, and other styles

31

Favril, Sophie, Eline Abma, Francesco Blasi, Emmelie Stock, Nausikaa Devriendt, Katrien Vanderperren, and Hilde de Rooster. "Clinical use of organic near-infrared fluorescent contrast agents in image-guided oncologic procedures and its potential in veterinary oncology." Veterinary Record 183, no. 11 (April 28, 2018): 354. http://dx.doi.org/10.1136/vr.104851.

Full text

Abstract:

One of the major challenges in surgical oncology is the intraoperative discrimination of tumoural versus healthy tissue. Until today, surgeons rely on visual inspection and palpation to define the tumoural margins during surgery and, unfortunately, for various cancer types, the local recurrence rate thus remains unacceptably high. Near-infrared (NIR) fluorescence imaging is an optical imaging technique that can provide real-time preoperative and intraoperative information after administration of a fluorescent probe that emits NIR light once exposed to a NIR light source. This technique is safe, cost-effective and technically easy. Several NIR fluorescent probes are currently studied for their ability to highlight neoplastic cells. In addition, NIR fluorescence imaging holds great promise for sentinel lymph node mapping. The aim of this manuscript is to provide a literature review of the current organic NIR fluorescent probes tested in the light of human oncology and to introduce fluorescence imaging as a valuable asset in veterinary oncology.

APA, Harvard, Vancouver, ISO, and other styles

32

Lereu, Aude L., Jacob P. Hoogenboom, and Niek F. van Hulst. "Gap Nanoantennas toward Molecular Plasmonic Devices." International Journal of Optics 2012 (2012): 1–19. http://dx.doi.org/10.1155/2012/502930.

Full text

Abstract:

Recently we have demonstrated that single fluorescent molecules can be used as non-perturbative vectorial probes of the local field. Here, we expand on such experiments exploiting fluorescence lifetime of single molecules to probe various types of gap nanoantennas. First, studies of the nanoantennas are carried out to evaluate the electric field. We then investigate hybrid systems composed by nanoantennas and randomly positioned fluorescent molecules. Finally, we present a fabrication scheme for the controlled placement of fluorescent molecules at welldefined positions with respect to the dimer nanoantenna, which is a more direct route to probe the local field in ana prioridetermined way.

APA, Harvard, Vancouver, ISO, and other styles

33

Tkachenko, Anton, Anatolii Onishchenko, Vladimir Klochkov, Nataliya Kavok, Oksana Nakonechna, Svetlana Yefimova, Yevgen Korniyenko, Igor Ryshchenko, and Yevgen Posokhov. "The impact of orally administered gadolinium orthovanadate GdVO4:Eu3+ nanoparticles on the state of phospholipid bilayer of erythrocytes." Turkish Journal of Biochemistry 45, no. 4 (August 19, 2020): 389–95. http://dx.doi.org/10.1515/tjb-2019-0427.

Full text

Abstract:

AbstractObjectivesTo assess the state of phospholipid bilayer of red blood cells (RBCs) in rats orally exposed to gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) during two weeks using fluorescent probes − ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole.MethodsSteady-state fluorescence spectroscopy: a study by the environment-sensitive fluorescent probes − 2-(2′-OH-phenyl)-5-phenyl-1,3-oxazole (probe O1O) and 2-(2′-OH-phenyl)-phenanthro[9,10]-1,3-oxazole (probe PH7).ResultsNo significant changes are detected in the spectra of the fluorescent probes bound to the RBCs from the rats orally exposed to nanoparticles in comparison with the corresponding spectra of the probes bound to the cells from the control group of animals. This indicates that, in case of the rats orally exposed to nanoparticles, no noticeable changes in physico-chemical properties (i.e., in the polarity and the proton-donor ability) are observed in the lipid membranes of RBCs in the region, where the probes locate.ConclusionsNo changes in the physical and chemical properties of the erythrocyte membranes are detected in the region from glycerol backbones of phospholipids to the center of the phospholipid bilayer in the rats orally exposed to VNPs during 2 weeks.

APA, Harvard, Vancouver, ISO, and other styles

34

Vengaian, K. Muthu, C. Denzil Britto, Gandhi Sivaraman, Karuppannan Sekar, and Subramanian Singaravadivel. "Phenothiazine based sensor for naked-eye detection and bioimaging of Hg(ii) and F− ions." RSC Advances 5, no. 115 (2015): 94903–8. http://dx.doi.org/10.1039/c5ra19341a.

Full text

Abstract:

The design and development of new phenothiazine-based fluorescent probes, which displays selective fluorescence response to Hg²⁺ and F⁻ ions in a reversible manner. The probe is the first example that facilitates the detection of Hg²⁺ at nanomolar concentration.

APA, Harvard, Vancouver, ISO, and other styles

35

Ismail, Ismail, Zhuoyue Chen, Xiuru Ji, Lu Sun, Long Yi, and Zhen Xi. "A Fast-Response Red Shifted Fluorescent Probe for Detection of H2S in Living Cells." Molecules 25, no. 3 (January 21, 2020): 437. http://dx.doi.org/10.3390/molecules25030437.

Full text

Abstract:

Near-infrared (NIR) fluorescent probes are attractive tools for bioimaging applications because of their low auto-fluorescence interference, minimal damage to living samples, and deep tissue penetration. H2S is a gaseous signaling molecule that is involved in redox homeostasis and numerous biological processes in vivo. To this end, we have developed a new red shifted fluorescent probe 1 to detect physiological H2S in live cells. The probe 1 is based on a rhodamine derivative as the red shifted fluorophore and the thiolysis of 7-nitro 1,2,3-benzoxadiazole (NBD) amine as the H2S receptor. The probe 1 displays fast fluorescent enhancement at 660 nm (about 10-fold turn-ons, k2 = 29.8 M−1s−1) after reacting with H2S in buffer (pH 7.4), and the fluorescence quantum yield of the activated red shifted product can reach 0.29. The probe 1 also exhibits high selectivity and sensitivity towards H2S. Moreover, 1 is cell-membrane-permeable and mitochondria-targeting, and can be used for imaging of endogenous H2S in living cells. We believe that this red shifted fluorescent probe can be a useful tool for studies of H2S biology.

APA, Harvard, Vancouver, ISO, and other styles

36

Fang, Xia, Bi, Wigstrom, Valenzano, Wang, Tanasova, Luck, and Liu. "Detecting Zn(II) Ions in Live Cells with Near-Infrared Fluorescent Probes." Molecules 24, no. 8 (April 22, 2019): 1592. http://dx.doi.org/10.3390/molecules24081592.

Full text

Abstract:

Two near-infrared fluorescent probes (A and B) containing hemicyanine structures appended to dipicolylamine (DPA), and a dipicolylamine derivative where one pyridine was substituted with pyrazine, respectively, were synthesized and tested for the identification of Zn(II) ions in live cells. In both probes, an acetyl group is attached to the phenolic oxygen atom of the hemicyanine platform to decrease the probe fluorescence background. Probe A displays sensitive fluorescence responses and binds preferentially to Zn(II) ions over other metal ions such as Cd2+ ions with a low detection limit of 0.45 nM. In contrast, the emission spectra of probe B is not significantly affected if Zn(II) ions are added. Probe A possesses excellent membrane permeability and low cytotoxicity, allowing for sensitive imaging of both exogenously supplemented Zn(II) ions in live cells, and endogenously releases Zn(II) ions in cells after treatment of 2,2-dithiodipyridine.

APA, Harvard, Vancouver, ISO, and other styles

37

Kay, Alan R., and Katalin Tóth. "Influence of Location of a Fluorescent Zinc Probe in Brain Slices on Its Response to Synaptic Activation." Journal of Neurophysiology 95, no. 3 (March 2006): 1949–56. http://dx.doi.org/10.1152/jn.00959.2005.

Full text

Abstract:

The precise role of the high concentration of ionic zinc found in the synaptic vesicles of certain glutamatergic terminals is unknown. Fluorescent probes with their ability to detect ions at low concentrations provide a powerful approach to monitoring cellular Zn2+ levels. In the last few years, a number of fluorescent probes (indicators) have been synthesized that can be used to visualize Zn2+ in live cells. The interpretation of data gathered using such probes depends crucially on the location of the probe. Using acutely prepared hippocampal slices, we provide evidence that the Zn2+ probes, ZnAF-2 and ZP4, are membrane permeant and are able to pass into synaptic vesicles. In addition, we show that changes in fluorescence of the Zn2+ probes can be used to monitor presynaptic activity; however, these changes are inconsistent with Zn2+ release.

APA, Harvard, Vancouver, ISO, and other styles

38

Jeong, Sanghwa, Darwin Yang, Abraham G. Beyene, Jackson Travis Del Bonis-O’Donnell, Anneliese M. M. Gest, Nicole Navarro, Xiaoqi Sun, and Markita P. Landry. "High-throughput evolution of near-infrared serotonin nanosensors." Science Advances 5, no. 12 (December 2019): eaay3771. http://dx.doi.org/10.1126/sciadv.aay3771.

Full text

Abstract:

Imaging neuromodulation with synthetic probes is an emerging technology for studying neurotransmission. However, most synthetic probes are developed through conjugation of fluorescent signal transducers to preexisting recognition moieties such as antibodies or receptors. We introduce a generic platform to evolve synthetic molecular recognition on the surface of near-infrared fluorescent single-wall carbon nanotube (SWCNT) signal transducers. We demonstrate evolution of molecular recognition toward neuromodulator serotonin generated from large libraries of ~6.9 × 1010 unique ssDNA sequences conjugated to SWCNTs. This probe is reversible and produces a ~200% fluorescence enhancement upon exposure to serotonin with a Kd = 6.3 μM, and shows selective responsivity over serotonin analogs, metabolites, and receptor-targeting drugs. Furthermore, this probe remains responsive and reversible upon repeat exposure to exogenous serotonin in the extracellular space of acute brain slices. Our results suggest that evolution of nanosensors could be generically implemented to develop other neuromodulator probes with synthetic molecular recognition.

APA, Harvard, Vancouver, ISO, and other styles

39

Milićević, David, and Jan Hlaváč. "Immobilized Fluorescent Probes for Simultaneous Multiple Protease Detection." Chemosensors 9, no. 6 (May 24, 2021): 119. http://dx.doi.org/10.3390/chemosensors9060119.

Full text

Abstract:

A new concept for simultaneous detection of two model proteases based on immobilized fluorescently labelled peptides was developed and evaluated. Each probe was composed of a carrier modified by poly(ethylene glycol) (PEG) chains, a specifically cleavable linker, and a fluorescent dye incorporated in the peptide tail. Based on a single excitation–double emission fluorescence response of liberated fluorophores caused by enzymatic cleavage, the presence of a single or both proteases in a mixture was unambiguously determined in an experimentally established concentration range. Among the tested solid supports, Rink Amide PEGA resin was recognized as the most suitable choice from the perspective of on-resin enzyme assays.

APA, Harvard, Vancouver, ISO, and other styles

40

Ma, Xiaohua, Yuanqiang Hao, Jiaxiang Liu, Guoguang Wu, and Lin Liu. "A Green-emitting Fluorescent Probe Based on a Benzothiazole Derivative for Imaging Biothiols in Living Cells." Molecules 24, no. 3 (January 23, 2019): 411. http://dx.doi.org/10.3390/molecules24030411.

Full text

Abstract:

A new green-emitting fluorescent probe 1 was developed for biothiol detection. The sensing mechanism was considered to be biothiol-induced cleavage of the 2,4-dinitrobenzene- sulfonate group in probe 1 and resulting inhibition of the probe’s photoinduced electron transfer (PET) process. Probe 1 exhibited favorable properties such as excellent selectivity, highly sensitive (0.12 µM), large Stokes shift (117 nm) and a remarkable turn-on fluorescence signal (148-fold). Furthermore, confocal fluorescence imaging indicated that probe 1 was membrane-permeable and suitable for visualization of biothiols in living A549 cells.

APA, Harvard, Vancouver, ISO, and other styles

41

Poole, C. A., N. H. Brookes, and G. M. Clover. "Keratocyte networks visualised in the living cornea using vital dyes." Journal of Cell Science 106, no. 2 (October 1, 1993): 685–91. http://dx.doi.org/10.1242/jcs.106.2.685.

Full text

Abstract:

Fluorescent viability probes have been used to visualise and investigate the viability, morphology and organisation of the keratocyte within the stroma of the intact living cornea. The live cell probe, calcien-AM, in combination with a dead cell probe, ethidium homodimer (Live/Dead Assay, Molecular Probes, U.S.A.) proved superior to earlier generation vital dyes such as fluorescein diacetate or 5,6-carboxyfluorescein diacetate, initially used in combination with ethidium bromide. The ubiquitous distribution of esterase enzymes that cleave calcien-AM within the keratocyte cytoplasm produced a high concentration of fluorescently active calcein throughout the cell, including fine cell processes. Epi-illuminated fluorescence microscopy on transparent corneal dissections subsequently revealed details of keratocyte microanatomy and three-dimensional network organisation in situ. Three morphologically discrete subpopulations of keratocytes were identified: two formed relatively small bands of cells, immediately subjacent to either Bowman's or Descemet's membranes, the third subpopulation constituting the majority of keratocytes typically located within the corneal stroma. The results indicate that calcein-AM is able to penetrate intact living cornea revealing cell viability, and it also has the capacity to ‘trace’ cellular elements and reveal fine structure within a dense connective tissue matrix.

APA, Harvard, Vancouver, ISO, and other styles

42

Dewitt, Sharon, Richard L. Darley, and Maurice B. Hallett. "Translocation or just location? Pseudopodia affect fluorescent signals." Journal of Cell Biology 184, no. 2 (January 26, 2009): 197–203. http://dx.doi.org/10.1083/jcb.200806047.

Full text

Abstract:

The use of fluorescent probes is one of the most powerful techniques for gaining spatial and temporal knowledge of dynamic events within living cells. Localized increases in the signal from cytosolic fluorescent protein constructs, for example, are frequently used as evidence for translocation of proteins to specific sites within the cell. However, differences in optical and geometrical properties of cytoplasm can influence the recorded intensity of the probe signal. Pseudopodia are especially problematic because their cytoplasmic properties can cause abrupt increases in fluorescent signal of both GFP and fluorescein. Investigators should therefore be cautious when interpreting fluorescence changes within a cell, as these can result from either translocation of the probe or changes in the optical properties of the milieu surrounding the probe.

APA, Harvard, Vancouver, ISO, and other styles

43

Fei-Peng, Zhu, Chen Guo-Tao, Wang Shou-Ju, Liu Ying, Tang Yu-Xia, Tian Ying, Wang Jian-Dong, et al. "Dual-Modality Imaging Probes with High Magnetic Relaxivity and Near-Infrared Fluorescence Based Highly Aminated Mesoporous Silica Nanoparticles." Journal of Nanomaterials 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/6502127.

Full text

Abstract:

Dual-modal imaging by combining magnetic resonance (MR) and near-infrared (NIR) fluorescence can integrate the advantages of high-resolution anatomical imaging with high sensitivity in vivo fluorescent imaging, which is expected to play a significant role in biomedical researches. Here we report a dual-modality imaging probe (NIR/MR-MSNs) fabricated by conjugating NIR fluorescent heptamethine dyes (IR-808) and MR contrast agents (Gd-DTPA) within highly aminated mesoporous silica nanoparticles (MSNs-NH2). The dual-modality imaging probes NIR/MR-MSNs possess a size of ca. 120 nm. The NIR/MR-MSNs show not only near-infrared fluorescence imaging property with an emission peak at 794 nm, but also highly MRT1relaxivity of 14.54 mM−1 s−1, which is three times more than Gd-DTPA. In vitro experiment reveals high uptake and retention abilities of the nanoprobes, while cell viability assay demonstrates excellent cytocompatibility of the dual-modality imaging probe. After intratumor injection with the NIR/MR-MSNs, MR imaging shows clear anatomical border of the enhanced tumor region while NIR fluorescence exhibits high sensitive tumor detection ability. These intriguing features suggest that this newly developed dual-modality imaging probes have great potential in biomedical imaging.

APA, Harvard, Vancouver, ISO, and other styles

44

Naya, Masami, and Chikara Sato. "Pyrene Excimer-Based Fluorescent Labeling of Cysteines Brought into Close Proximity by Protein Dynamics: ASEM-Induced Thiol-Ene Click Reaction for High Spatial Resolution CLEM." International Journal of Molecular Sciences 21, no. 20 (October 13, 2020): 7550. http://dx.doi.org/10.3390/ijms21207550.

Full text

Abstract:

Fluorescence microscopy (FM) has revealed vital molecular mechanisms of life. Mainly, molecules labeled by fluorescent probes are imaged. However, the diversity of labeling probes and their functions remain limited. We synthesized a pyrene-based fluorescent probe targeting SH groups, which are important for protein folding and oxidative stress sensing in cells. The labeling achieved employs thiol-ene click reactions between the probes and SH groups and is triggered by irradiation by UV light or an electron beam. When two tagged pyrene groups were close enough to be excited as a dimer (excimer), they showed red-shifted fluorescence; theoretically, the proximity of two SH residues within ~30 Å can thus be monitored. Moreover, correlative light/electron microscopy (CLEM) was achieved using our atmospheric scanning electron microscope (ASEM); radicals formed in liquid by the electron beam caused the thiol-ene click reactions, and excimer fluorescence of the labeled proteins in cells and tissues was visualized by FM. Since the fluorescent labeling is induced by a narrow electron beam, high spatial resolution labeling is expected. The method can be widely applied to biological fields, for example, to study protein dynamics with or without cysteine mutagenesis, and to beam-induced micro-fabrication and the precise post-modification of materials.

APA, Harvard, Vancouver, ISO, and other styles

45

Lin, Jiarun, Marcus E. Graziotto, Peter A. Lay, and Elizabeth J. New. "A Bimodal Fluorescence-Raman Probe for Cellular Imaging." Cells 10, no. 7 (July 5, 2021): 1699. http://dx.doi.org/10.3390/cells10071699.

Full text

Abstract:

Biochemical changes in specific organelles underpin cellular function, and studying these changes is crucial to understand health and disease. Fluorescent probes have become important biosensing and imaging tools as they can be targeted to specific organelles and can detect changes in their chemical environment. However, the sensing capacity of fluorescent probes is highly specific and is often limited to a single analyte of interest. A novel approach to imaging organelles is to combine fluorescent sensors with vibrational spectroscopic imaging techniques; the latter provides a comprehensive map of the relative biochemical distributions throughout the cell to gain a more complete picture of the biochemistry of organelles. We have developed NpCN1, a bimodal fluorescence-Raman probe targeted to the lipid droplets, incorporating a nitrile as a Raman tag. NpCN1 was successfully used to image lipid droplets in 3T3-L1 cells in both fluorescence and Raman modalities, reporting on the chemical composition and distribution of the lipid droplets in the cells.

APA, Harvard, Vancouver, ISO, and other styles

46

Huang, Jingfan, and Frank V. Bright. "Microheterogeneity of Sodium Dodecylsulfate Micelles Probed by Frequency-Domain Fluorometry." Applied Spectroscopy 46, no. 2 (February 1992): 329–39. http://dx.doi.org/10.1366/0003702924125663.

Full text

Abstract:

The microenvironment of sodium dodecylsulfate (SDS) micelles has been examined with the use of two fluorescent probes, 2-anilinonaphthalene-6-sulfonic acid (2,6-ANS) and N-phenyl-naphthylamine (1-AN). The fluorescence lifetimes are recovered from multifrequency phase and modulation data with the use of a global analysis protocol. The fluorescence decay kinetics of 2,6-ANS, which probes the outer-core region (i.e., the palisade layer) of SDS micelles, is characterized by a Lorentzian distribution. In contrast, a single discrete excited-state lifetime is observed for 1-AN, which is expected to position itself in the inner-core region of the micelle. Fluorescence lifetimes of these probes are investigated also as functions of temperature, concentration of counter ions (Na+ and Mg2+) and linear alcohols ( n-BuOH, n-PeOH, n-HeOH, and n-HepOH). The collective results confirm that the outer-core region of SDS micelles is microheterogeneous and the inner core is essentially homogeneous. In addition, the lifetimes and the partitioning of the outer-core probe, 2,6-ANS, appear to be more sensitive to variations in temperature and counter ions in comparison to those of the inner-core probe, 1-AN. The microenvironment of 2,6-ANS is found to be more heterogeneous at high temperature and low salt concentrations. This observation, we propose, is a result of different degrees of water penetration in the outer-core region. In the SDS system, the effects of micelle polydispersity and compositional diversity, on the environmental microheterogeneity of the fluorescent probe, seem to be minimal in comparison to water gradient effects.

APA, Harvard, Vancouver, ISO, and other styles

47

Wang, Zhenghui, Ke Zhang, Karen L. Wooley, and John-Stephen Taylor. "Imaging mRNA Expression in Live Cells via PNA·DNA Strand Displacement-Activated Probes." Journal of Nucleic Acids 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/962652.

Full text

Abstract:

Probes for monitoring mRNA expressionin vivoare of great interest for the study of biological and biomedical problems, but progress has been hampered by poor signal to noise and effective means for delivering the probes into live cells. Herein we report a PNA·DNA strand displacement-activated fluorescent probe that can image the expression of iNOS (inducible nitric oxide synthase) mRNA, a marker of inflammation. The probe consists of a fluorescein labeled antisense PNA annealed to a shorterDABCYLplus-labeled DNA which quenches the fluorescence, but when the quencher strand is displaced by the target mRNA the fluorescence is restored. DNA was used for the quencher strand to facilitate electrostatic binding of the otherwise netural PNA strand to a cationic shell crosslinked knedel-like (cSCK) nanoparticle which can deliver the PNA·DNA duplex probe into cells with less toxicity and greater efficiency than other transfection agents. RAW 264.7 mouse macrophage cells transfected with the iNOS PNA·DNA probe via the cSCK showed a 16 to 54-fold increase in average fluorescence per cell upon iNOS stimulation. The increase was 4 to 7-fold higher than that for a non-complementary probe, thereby validating the ability of a PNA·DNA strand displacement-activated probe to image mRNA expressionin vivo.

APA, Harvard, Vancouver, ISO, and other styles

48

Zhang, Yibin, Jianheng Bi, Shuai Xia, Wafa Mazi, Shulin Wan, Logan Mikesell, Rudy Luck, and Haiying Liu. "A Near-Infrared Fluorescent Probe Based on a FRET Rhodamine Donor Linked to a Cyanine Acceptor for Sensitive Detection of Intracellular pH Alternations." Molecules 23, no. 10 (October 18, 2018): 2679. http://dx.doi.org/10.3390/molecules23102679.

Full text

Abstract:

A fluorescence resonance energy transfer (FRET)-based near-infrared fluorescent probe (B+) for double-checked sensitive detection of intracellular pH changes has been synthesized by binding a near-infrared rhodamine donor to a near-infrared cyanine acceptor through robust C-N bonds via a nucleophilic substitution reaction. To demonstrate the double-checked advantages of probe B+, a near-infrared probe (A) was also prepared by modification of a near-infrared rhodamine dye with ethylenediamine to produce a closed spirolactam residue. Under basic conditions, probe B+ shows only weak fluorescence from the cyanine acceptor while probe A displays nonfluorescence due to retention of the closed spirolactam form of the rhodamine moiety. Upon decrease in solution pH level, probe B+ exhibits a gradual fluorescence increase from rhodamine and cyanine constituents at 623 nm and 743 nm respectively, whereas probe A displays fluorescence increase at 623 nm on the rhodamine moiety as acidic conditions leads to the rupture of the probe spirolactam rings. Probes A and B+ have successfully been used to monitor intracellular pH alternations and possess pKa values of 5.15 and 7.80, respectively.

APA, Harvard, Vancouver, ISO, and other styles

49

Espósito, B. P., W. Breuer, and Z. I. Cabantchik. "Design and applications of methods for fluorescence detection of iron in biological systems." Biochemical Society Transactions 30, no. 4 (August 1, 2002): 729–32. http://dx.doi.org/10.1042/bst0300729.

Full text

Abstract:

Fluorescence metalosensors provide a means to detect iron in biological systems that is versatile, economical, sensitive and of a high-throughput nature. They rely on relatively high-affinity iron-binding carriers conjugated to highly fluorescent probes that undergo quenching after metal complexation. Metal specificity is determined by probes containing either an iron-binding moiety of high affinity (type A) or of relatively lower affinity (type B) used in combination with a strong specific iron chelator. Due to the heterogeneous nature of biological systems, the apparent metal-binding affinity and complexation stoichiometry ought to be specifically defined. Fluoresceinated moieties coupled to metal-binding cores detect Fe at sub-micromolar concentrations and even sub-microlitre volumes (i.e. cells). Although an ideal probe should also be specific for a particular oxidation state of iron, in physiological conditions that property might be difficult to attain. Quantification of labile iron in cells has relied on the ability of permeant iron chelators to restore the fluorescence of probes quenched by intracellular Fe. Modern design of probes aims to (a) improve probe targeting to specific cell compartments and (b) create probes that respond to metal binding by signal enhancement.

APA, Harvard, Vancouver, ISO, and other styles

50

Xiao, Ying, Adya P. Singh, and Robin N. Wakeling. "Detecting Bacteria in Wood using a Fluorescent Lipid Probe." Microscopy Today 6, no. 7 (September 1998): 16–17. http://dx.doi.org/10.1017/s1551929500068632.

Full text

Abstract:

Wood cells have strong autofluorescence in a wide wavelength band due to lignin in the cell walls. The detection of microorganisms in wood is very difficult when using fluorescent microscopy because of interferences. We have recently developed fluorescent staining techniques to differentiate fungal hyphae from wood cell walls (Singh, et al., 1997; Xiao, et al., 1997). This study was aimed at developing fluorescent techniques to visualize bacteria in wood using confocal laser scanning microscopy (CLSM). Nitrobenzoxadiazole glycerophosphoethanolamine (NBD-PE, Molecular Probes), a widely used membrane probe which accords strong fluorescence upon lipids, was compared with glutaraldehyde which had proved useful in our initial attempts to visualize fungal hyphae in wood because of the cell auto fluorescence it causes (Singh et al., 1997).

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Fluorescents probes'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles