WorldWideScience

Sample records for fluorescence based molecular

  1. Fluorescence based molecular in vivo imaging

    International Nuclear Information System (INIS)

    Ebert, Bernd

    2008-01-01

    Molecular imaging represents a modern research area that allows the in vivo study of molecular biological process kinetics using appropriate probes and visualization methods. This methodology may be defined- apart from the contrast media injection - as non-abrasive. In order to reach an in vivo molecular process imaging as accurate as possible the effects of the used probes on the biological should not be too large. The contrast media as important part of the molecular imaging can significantly contribute to the understanding of molecular processes and to the development of tailored diagnostics and therapy. Since more than 15 years PTB is developing optic imaging systems that may be used for fluorescence based visualization of tissue phantoms, small animal models and the localization of tumors and their predecessors, and for the early recognition of inflammatory processes in clinical trials. Cellular changes occur during many diseases, thus the molecular imaging might be of importance for the early diagnosis of chronic inflammatory diseases. Fluorescent dyes can be used as unspecific or also as specific contrast media, which allow enhanced detection sensitivity

  2. Highly Selective Fluorescent Sensing of Proteins Based on a Fluorescent Molecularly Imprinted Nanosensor

    Directory of Open Access Journals (Sweden)

    Shuo Wang

    2013-09-01

    Full Text Available A fluorescent molecularly imprinted nanosensor was obtained by grafting imprinted polymer onto the surface of multi-wall carbon nanotubes and post-imprinting treatment with fluorescein isothiocyanate (FITC. The fluorescence of lysozyme-imprinted polymer (Lys-MIP was quenched more strongly by Lys than that of nonimprinted polymer (NIP, which indicated that the Lys-MIP could recognize Lys. The resulted imprinted material has the ability to selectively sense a target protein, and an imprinting factor of 3.34 was achieved. The Lys-MIP also showed selective detection for Lys among other proteins such as cytochrome C (Cyt C, hemoglobin (HB and bovine serum albumin (BSA due to the imprinted sites in the Lys-MIP. This approach combines the high selectivity of surface molecular imprinting technology and fluorescence, and converts binding events into detectable signals by monitoring fluorescence spectra. Therefore, it will have further applications for Lys sensing.

  3. An eco-friendly molecularly imprinted fluorescence composite material based on carbon dots for fluorescent detection of 4-nitrophenol

    International Nuclear Information System (INIS)

    Hao, Tongfan; Wei, Xiao; Nie, Yijing; Zhou, Zhiping; Xu, Yeqing; Yan, Yongsheng

    2016-01-01

    We on report an eco-friendly molecularly imprinted material based on carbon dots (C-dots) via a facile and efficient sol–gel polymerization for selective fluorescence detection of 4-nitrophenol (4-NP). The amino-modified C-dots were firstly synthesized by a hydrothermal process using citric acid as the carbon source and poly(ethyleneimine) as the surface modifier, and then after a sol–gel molecular imprinting process, the molecularly imprinted fluorescence material was obtained. The material (MIP-C-dots) showed strong fluorescence from C-dots and high selectivity due to the presence of a molecular imprint. After the detection conditions were optimized, the relative fluorescence intensity (F_0/F) of MIP-C-dots presented a good linearity with 4-NP concentrations in the linear range of 0.2 − 50 μmol L"-"1 with a detection limit (3σ/k) of 0.06 μmol L"-"1. In addition, the correlation coefficient was 0.9978 and the imprinting factor was 2.76. The method was applicable to the determination of trace 4-NP in Yangtze River water samples and good recoveries from 92.6–107.3 % were obtained. The present study provides a general strategy to fabricate materials based on C-dots with good fluorescence property for selective fluorescence detection of organic pollutants. (author)

  4. Molecularly imprinted fluorescent probe based on FRET for selective and sensitive detection of doxorubicin

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhifeng, E-mail: 897061147@qq.com [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Deng, Peihong; Li, Junhua [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China); Xu, Li [Department of Applied Chemistry, College of Materials and Energy, South China Agricultural University, Guangzhou 510642 (China); Tang, Siping [College of Chemistry and Materials Science, Hengyang Normal University, Key Laboratory of Functional Organometallic Materials of Hunan Province University, Hengyang 421008 (China)

    2017-04-15

    Highlights: • FRET-based molecularly imprinted probe for detection of doxorubicin was prepared. • The detection limit of the probe was 13.8 nM for doxorubicin. • The FRET-based probe had a higher selectivity for the template than ordinary MIMs. - Abstract: In this work, a new type of fluorescent probe for detection of doxorubicin has been constructed by the combined use of fluorescence resonance energy transfer (FRET) technology and molecular imprinting technique (MIT). Using doxorubicin as the template, the molecularly imprinted polymer thin layer was fabricated on the surfaces of carbon dot (CD) modified silica by sol-gel polymerization. The excitation energy of the fluorescent donor (CDs) could be transferred to the fluorescent acceptor (doxorubicin). The FRET based fluorescent probe demonstrated high sensitivity and selectivity for doxorubicin. The detection limit was 13.8 nM. The fluorescent probe was successfully applied for detecting doxorubicin in doxorubicin-spiked plasmas with a recovery of 96.8–103.8%, a relative standard deviation (RSD) of 1.3–2.8%. The strategy for construction of FRET-based molecularly imprinted materials developed in this work is very promising for analytical applications.

  5. Strategies of molecular imprinting-based fluorescence sensors for chemical and biological analysis.

    Science.gov (United States)

    Yang, Qian; Li, Jinhua; Wang, Xiaoyan; Peng, Hailong; Xiong, Hua; Chen, Lingxin

    2018-07-30

    One pressing concern today is to construct sensors that can withstand various disturbances for highly selective and sensitive detecting trace analytes in complicated samples. Molecularly imprinted polymers (MIPs) with tailor-made binding sites are preferred to be recognition elements in sensors for effective targets detection, and fluorescence measurement assists in highly sensitive detection and user-friendly control. Accordingly, molecular imprinting-based fluorescence sensors (MI-FL sensors) have attracted great research interest in many fields such as chemical and biological analysis. Herein, we comprehensively review the recent advances in MI-FL sensors construction and applications, giving insights on sensing principles and signal transduction mechanisms, focusing on general construction strategies for intrinsically fluorescent or nonfluorescent analytes and improvement strategies in sensing performance, particularly in sensitivity. Construction strategies are well overviewed, mainly including the traditional indirect methods of competitive binding against pre-bound fluorescent indicators, employment of fluorescent functional monomers and embedding of fluorescence substances, and novel rational designs of hierarchical architecture (core-shell/hollow and mesoporous structures), post-imprinting modification, and ratiometric fluorescence detection. Furthermore, MI-FL sensor based microdevices are discussed, involving micromotors, test strips and microfluidics, which are more portable for rapid point-of-care detection and in-field diagnosing. Finally, the current challenges and future perspectives of MI-FL sensors are proposed. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Selective detection of heavy metal ions by calixarene-based fluorescent molecular sensors

    Science.gov (United States)

    Zhang, Haitao; Faye, Djibril; Zhang, Han; Lefevre, Jean-Pierre; Delaire, J. A.; Leray, Isabelle

    2012-06-01

    The synthesis, spectroscopic characterization and complexing properties of calixarene-based fluorescent sensors are reported. The calixarene bearing four dansyl fluorophores (Calix-DANS4) exhibits a very high affinity for the detection of lead. A fluorimetric micro-device based on the use of a Y-shape microchannel was developed and allows lead detection with a 5 ppb detection limit. For mercury detection, a fluorescent molecular sensor containing a calixarene anchored with four 8-quinolinoloxy groups (Calix-Q) has been synthesized. The absorption and fluorescence spectra of this sensor are sensitive to the presence of metal cations. An efficient fluorescence quenching is observed upon mercury complexation because of a photoinduced electron transfer from the fluorophore to the bound mercury. Calix-Q shows a high selectivity towards Hg2+ over interfering cations (Na+, K+, Ca2+, Cu2+, Zn2+, Cd2+ and Pb2+) and a 70 ppb sensitivity.

  7. Facilitating in vivo tumor localization by principal component analysis based on dynamic fluorescence molecular imaging

    Science.gov (United States)

    Gao, Yang; Chen, Maomao; Wu, Junyu; Zhou, Yuan; Cai, Chuangjian; Wang, Daliang; Luo, Jianwen

    2017-09-01

    Fluorescence molecular imaging has been used to target tumors in mice with xenograft tumors. However, tumor imaging is largely distorted by the aggregation of fluorescent probes in the liver. A principal component analysis (PCA)-based strategy was applied on the in vivo dynamic fluorescence imaging results of three mice with xenograft tumors to facilitate tumor imaging, with the help of a tumor-specific fluorescent probe. Tumor-relevant features were extracted from the original images by PCA and represented by the principal component (PC) maps. The second principal component (PC2) map represented the tumor-related features, and the first principal component (PC1) map retained the original pharmacokinetic profiles, especially of the liver. The distribution patterns of the PC2 map of the tumor-bearing mice were in good agreement with the actual tumor location. The tumor-to-liver ratio and contrast-to-noise ratio were significantly higher on the PC2 map than on the original images, thus distinguishing the tumor from its nearby fluorescence noise of liver. The results suggest that the PC2 map could serve as a bioimaging marker to facilitate in vivo tumor localization, and dynamic fluorescence molecular imaging with PCA could be a valuable tool for future studies of in vivo tumor metabolism and progression.

  8. A distance-dependent metal-enhanced fluorescence sensing platform based on molecular beacon design.

    Science.gov (United States)

    Zhou, Zhenpeng; Huang, Hongduan; Chen, Yang; Liu, Feng; Huang, Cheng Zhi; Li, Na

    2014-02-15

    A new metal-enhanced fluorescence (MEF) based platform was developed on the basis of distance-dependent fluorescence quenching-enhancement effect, which combined the easiness of Ag-thiol chemistry with the MEF property of noble-metal structures as well as the molecular beacon design. For the given sized AgNPs, the fluorescence enhancement factor was found to increase with a d(6) dependency in agreement with fluorescence resonance energy transfer mechanism at shorter distance and decrease with a d(-3) dependency in agreement with plasmonic enhancement mechanism at longer distance between the fluorophore and the AgNP surface. As a proof of concept, the platform was demonstrated by a sensitive detection of mercuric ions, using thymine-containing molecular beacon to tune silver nanoparticle (AgNP)-enhanced fluorescence. Mercuric ions were detected via formation of a thymine-mercuric-thymine structure to open the hairpin, facilitating fluorescence recovery and AgNP enhancement to yield a limit of detection of 1 nM, which is well below the U.S. Environmental Protection Agency regulation of the Maximum Contaminant Level Goal (10nM) in drinking water. Since the AgNP functioned as not only a quencher to reduce the reagent blank signal but also an enhancement substrate to increase fluorescence of the open hairpin when target mercuric ions were present, the quenching-enhancement strategy can greatly improve the detection sensitivity and can in principle be a universal approach for various targets when combined with molecular beacon design. © 2013 Elsevier B.V. All rights reserved.

  9. Innovative molecular-based fluorescent nanoparticles for multicolor single particle tracking in cells

    International Nuclear Information System (INIS)

    Daniel, Jonathan; Blanchard-Desce, Mireille; Godin, Antoine G; Palayret, Matthieu; Lounis, Brahim; Cognet, Laurent

    2016-01-01

    Based on an original molecular-based design, we present bright and photostable fluorescent organic nanoparticles (FONs) showing excellent colloidal stability in various aqueous environments. Complementary near-infrared emitting and green emitting FONs were prepared using a simple, fast and robust protocol. Both types of FONs could be simultaneously imaged at the single-particle level in solution as well as in biological environments using a monochromatic excitation and a dual-color fluorescence microscope. No evidence of acute cytotoxicity was found upon incubation of live cells with mixed solutions of FONs, and both types of nanoparticles were found internalized in the cells where their motion could be simultaneously tracked at video-rate up to minutes. These fluorescent organic nanoparticles open a novel non-toxic alternative to existing nanoparticles for imaging biological structures, compatible with live-cell experiments and specially fitted for multicolor single particle tracking. (paper)

  10. Cucurbiturils: molecular nanocapsules for time-resolved fluorescence-based assays.

    Science.gov (United States)

    Marquez, Cesar; Huang, Fang; Nau, Werner M

    2004-03-01

    A new fluorescent host-guest system based on the inclusion of the fluorophore 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) into the cavity of the molecular container compound cucurbit[7]uril (CB7) has been designed which possesses an exceedingly long-lived emission (690 ns in aerated water). The large binding constant of (4 +/- 1) x 10(5) M(-1) along with the resistance of the CB7.DBO complex toward external fluorescence quenchers allow the use of CB7 as an enhancer in time-resolved fluorescence-based assays, e.g., to screen enzyme activity or inhibition by using DBO-labeled peptides as substrates. The response of CB7.DBO to different environmental conditions and possible quenchers are described.

  11. Chemodosimeter-based fluorescent detection of L-cysteine after extracted by molecularly imprinted polymers.

    Science.gov (United States)

    Cai, Xiaoqiang; Li, Jinhua; Zhang, Zhong; Wang, Gang; Song, Xingliang; You, Jinmao; Chen, Lingxin

    2014-03-01

    A chemodosimeter-based fluorescent detection method coupled with molecularly imprinted polymers (MIPs) extraction was developed for determination of L-cysteine (L-Cys) by combining molecular imprinting technique with fluorescent chemodosimeter. The MIPs prepared by precipitation polymerization with L-Cys as template, possessed high specific surface area of 145 m(2)/g and good thermal stability without decomposition lower than 300 °C, and were successfully applied as an adsorbent with excellent selectivity for L-Cys over other amino acids, and enantioselectivity was also demonstrated. A novel chemodosimeter, rhodamine B1, was synthesized for discriminating L-Cys from its structurally similar homocysteine and glutathione as well as various possibly co-existing biospecies in aqueous solutions with notable fluorescence enhancement when adding L-Cys. As L-Cys was added with increasing concentrations, an emission band peaked at 580 nm occurred and significantly increased in fluorescence intensity, by which the L-Cys could be sensed optically. High detectability up to 12.5 nM was obtained. An excellent linearity was found within the wide range of 0.05-50 μM (r=0.9996), and reasonable relative standard deviations ranging from 0.3% to 3.5% were attained. Such typical features as high selectivity, high sensitivity, easy operation and low cost enabled this MIPs-fluorometry to be potentially applicable for routine detection of trace L-Cys. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Efficient L1 regularization-based reconstruction for fluorescent molecular tomography using restarted nonlinear conjugate gradient.

    Science.gov (United States)

    Shi, Junwei; Zhang, Bin; Liu, Fei; Luo, Jianwen; Bai, Jing

    2013-09-15

    For the ill-posed fluorescent molecular tomography (FMT) inverse problem, the L1 regularization can protect the high-frequency information like edges while effectively reduce the image noise. However, the state-of-the-art L1 regularization-based algorithms for FMT reconstruction are expensive in memory, especially for large-scale problems. An efficient L1 regularization-based reconstruction algorithm based on nonlinear conjugate gradient with restarted strategy is proposed to increase the computational speed with low memory consumption. The reconstruction results from phantom experiments demonstrate that the proposed algorithm can obtain high spatial resolution and high signal-to-noise ratio, as well as high localization accuracy for fluorescence targets.

  13. Fluorescent molecularly imprinted polymer based on Navicula sp. frustules for optical detection of lysozyme.

    Science.gov (United States)

    Lim, Guat Wei; Lim, Jit Kang; Ahmad, Abdul Latif; Chan, Derek Juinn Chieh

    2016-03-01

    The direct correlation between disease and lysozyme (LYZ) levels in human body fluids makes the sensitive and convenient detection of LYZ the focus of scientific research. Fluorescent molecularly imprinted polymer has emerged as a new alternative for LYZ detection in order to resolve the limitation of immunoassays, which are expensive, unstable, require complex preparation, and are time consuming. In this study, a novel fluorescence molecularly imprinted polymer based on Navicula sp. frustules (FITC-MIP) has been synthesized via post-imprinting treatment for LYZ detection. Navicula sp. frustules were used as supported material because of their unique properties of moderate surface area, reproducibility, and biocompatibility, to address the drawbacks of nanoparticle core material with low adsorption capacity. The FITC acts as recognition signal and optical readout, whereas MIP provides LYZ selectivity. The synthesized FITC-MIP showed a response time as short as 5 min depending on the concentration of LYZ. It is found that the LYZ template can significantly quench the fluorescence intensity of FITC-MIP linearly within a concentration range of 0 to 0.025 mg mL(-1), which is well described by Stern-Volmer equation. The FITC-MIP can selectively and sensitively detect down to 0.0015 mg mL(-1) of LYZ concentration. The excellent sensing performance of FITC-MIP suggests that FITC-MIP is a potential biosensor in clinical diagnosis applications.

  14. A three-step reconstruction method for fluorescence molecular tomography based on compressive sensing

    DEFF Research Database (Denmark)

    Zhu, Yansong; Jha, Abhinav K.; Dreyer, Jakob K.

    2017-01-01

    Fluorescence molecular tomography (FMT) is a promising tool for real time in vivo quantification of neurotransmission (NT) as we pursue in our BRAIN initiative effort. However, the acquired image data are noisy and the reconstruction problem is ill-posed. Further, while spatial sparsity of the NT...... matrix coherence. The resultant image data are input to a homotopy-based reconstruction strategy that exploits sparsity via ℓ1 regularization. The reconstructed image is then input to a maximum-likelihood expectation maximization (MLEM) algorithm that retains the sparseness of the input estimate...... and improves upon the quantitation by accurate Poisson noise modeling. The proposed reconstruction method was evaluated in a three-dimensional simulated setup with fluorescent sources in a cuboidal scattering medium with optical properties simulating human brain cortex (reduced scattering coefficient: 9.2 cm-1...

  15. Reconstruction for limited-projection fluorescence molecular tomography based on projected restarted conjugate gradient normal residual.

    Science.gov (United States)

    Cao, Xu; Zhang, Bin; Liu, Fei; Wang, Xin; Bai, Jing

    2011-12-01

    Limited-projection fluorescence molecular tomography (FMT) can greatly reduce the acquisition time, which is suitable for resolving fast biology processes in vivo but suffers from severe ill-posedness because of the reconstruction using only limited projections. To overcome the severe ill-posedness, we report a reconstruction method based on the projected restarted conjugate gradient normal residual. The reconstruction results of two phantom experiments demonstrate that the proposed method is feasible for limited-projection FMT. © 2011 Optical Society of America

  16. Nitrogen-doped graphene quantum dots-based fluorescence molecularly imprinted sensor for thiacloprid detection.

    Science.gov (United States)

    Liu, Yang; Cao, Nan; Gui, Wenying; Ma, Qiang

    2018-06-01

    In this paper, a test strip-based sensor was developed for thiacloprid quantitative detection based on PDA molecularly imprinted polymer (MIP) and nitrogen-doped graphene quantum dots (N-GQDs). Thiacloprid is a new type of nicotine insecticide, which can block the normal neurotransmitter delivery process in insects. In the sensing system, N-GQDs were immersed into filter paper at first. Then, dopamine (DA) with thiacloprid can be self-polymerized on test strip surface to form the uniform PDA film. After removed thiacloprid template, the established poly dopamine (PDA) MIP can selectively recognize thiacloprid. As a result, captured thiacloprid can enhance the fluorescence intensity of N-GQDs into the test strip. As a result, the fluorescence intensity of N-GQDs can be linearly related within a certain range of thiacloprid concentration. Under the optimum conditions, the proposed sensor for thiacloprid detection exhibited a linear ranging from 0.1 mg/L to 10 mg/L with a low detection limit of 0.03 mg/L. The N-GQDs based test strip-based sensor for thiaclopridis reported for the first time. The sensing system has high selectivity to thiacloprid and provides new opportunities in the pesticide detection. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Optimization and performance evaluation of a conical mirror based fluorescence molecular tomography imaging system

    Science.gov (United States)

    Zhao, Yue; Zhang, Wei; Zhu, Dianwen; Li, Changqing

    2016-03-01

    We performed numerical simulations and phantom experiments with a conical mirror based fluorescence molecular tomography (FMT) imaging system to optimize its performance. With phantom experiments, we have compared three measurement modes in FMT: the whole surface measurement mode, the transmission mode, and the reflection mode. Our results indicated that the whole surface measurement mode performed the best. Then, we applied two different neutral density (ND) filters to improve the measurement's dynamic range. The benefits from ND filters are not as much as predicted. Finally, with numerical simulations, we have compared two laser excitation patterns: line and point. With the same excitation position number, we found that the line laser excitation had slightly better FMT reconstruction results than the point laser excitation. In the future, we will implement Monte Carlo ray tracing simulations to calculate multiple reflection photons, and create a look-up table accordingly for calibration.

  18. Fluorescence- and capillary electrophoresis (CE)-based SSR DNA fingerprinting and a molecular identity database for the Louisiana sugarcane industry

    Science.gov (United States)

    A database of Louisiana sugarcane molecular identity has been constructed and is being updated annually using FAM or HEX or NED fluorescence- and capillary electrophoresis (CE)-based microsatellite (SSR) fingerprinting information. The fingerprints are PCR-amplified from leaf DNA samples of current ...

  19. [Molecular beacon based PNA-FISH method combined with fluorescence scanning for rapid detection of Listeria monocytogenes].

    Science.gov (United States)

    Wu, Shan; Zhang, Xiaofeng; Shuai, Jiangbing; Li, Ke; Yu, Huizhen; Jin, Chenchen

    2016-07-04

    To simplify the PNA-FISH (Peptide nucleic acid-fluorescence in situ hybridization) test, molecular beacon based PNA probe combined with fluorescence scanning detection technology was applied to replace the original microscope observation to detect Listeria monocytogenes The 5′ end and 3′ end of the L. monocytogenes specific PNA probes were labeled with the fluorescent group and the quenching group respectively, to form a molecular beacon based PNA probe. When PNA probe used for fluorescence scanning and N1 treatment as the control, the false positive rate was 11.4%, and the false negative rate was 0; when N2 treatment as the control, the false positive rate decreased to 4.3%, but the false negative rate rose to 18.6%. When beacon based PNA probe used for fluorescence scanning, taken N1 treatment as blank control, the false positive rate was 8.6%, and the false negative rate was 1.4%; taken N2 treatment as blank control, the false positive rate was 5.7%, and the false negative rate was 1.4%. Compared with PNA probe, molecular beacon based PNA probe can effectively reduce false positives and false negatives. The success rates of hybridization of the two PNA probes were 83.3% and 95.2% respectively; and the rates of the two beacon based PNA probes were 91.7% and 90.5% respectively, which indicated that labeling the both ends of the PNA probe dose not decrease the hybridization rate with the target bacteria. The combination of liquid phase PNA-FISH and fluorescence scanning method, can significantly improve the detection efficiency.

  20. Fluorescent molecular probes based on excited state prototropism in lipid bilayer membrane

    Science.gov (United States)

    Mohapatra, Monalisa; Mishra, Ashok K.

    2012-03-01

    Excited state prototropism (ESPT) is observed in molecules having one or more ionizable protons, whose proton transfer efficiency is different in ground and excited states. The interaction of various ESPT molecules like naphthols and intramolecular ESPT (ESIPT) molecules like hydroxyflavones etc. with different microheterogeneous media have been studied in detail and excited state prototropism as a probe concept has been gaining ground. The fluorescence of different prototropic forms of such molecules, on partitioning to an organized medium like lipid bilayer membrane, often show sensitive response to the local environment with respect to the local structure, physical properties and dynamics. Our recent work using 1-naphthol as an ESPT fluorescent molecular probe has shown that the incorporation of monomeric bile salt molecules into lipid bilayer membranes composed from dipalmitoylphosphatidylcholine (DPPC, a lung surfactant) and dimyristoylphosphatidylcholine (DMPC), in solid gel and liquid crystalline phases, induce appreciable wetting of the bilayer up to the hydrocarbon core region, even at very low (fisetin, an ESIPT molecule having antioxidant properties, in lipid bilayer membrane has been sensitively monitored from its intrinsic fluorescence behaviour.

  1. Fluorescence molecular tomography in the presence of background fluorescence

    International Nuclear Information System (INIS)

    Soubret, Antoine; Ntziachristos, Vasilis

    2006-01-01

    Fluorescence molecular tomography is an emerging imaging technique that resolves the bio-distribution of engineered fluorescent probes developed for in vivo reporting of specific cellular and sub-cellular targets. The method can detect fluorochromes in picomole amounts or less, imaged through entire animals, but the detection sensitivity and imaging performance drop in the presence of background, non-specific fluorescence. In this study, we carried out a theoretical and an experimental investigation on the effect of background fluorescence on the measured signal and on the tomographic reconstruction. We further examined the performance of three subtraction methods based on physical models of photon propagation, using experimental data on phantoms and small animals. We show that the data pre-processing with subtraction schemes can improve image quality and quantification when non-specific background florescence is present

  2. Simple fluorescence-based detection of protein kinase A activity using a molecular beacon probe.

    Science.gov (United States)

    Ma, Changbei; Lv, Xiaoyuan; Wang, Kemin; Jin, Shunxin; Liu, Haisheng; Wu, Kefeng; Zeng, Weimin

    2017-11-02

    Protein kinase A was detected by quantifying the amount of ATP used after a protein kinase reaction. The ATP assay was performed using the T4 DNA ligase and a molecular beacon (MB). In the presence of ATP, DNA ligase catalyzed the ligation of short DNA. The ligation product then hybridized to MB, resulting in a fluorescence enhancement of the MB. This assay was capable of determining protein kinase A in the range of 12.5∼150 nM, with a detection limit of 1.25 nM. Furthermore, this assay could also be used to investigate the effect of genistein on protein kinase A. It was a universal, non-radioisotopic, and homogeneous method for assaying protein kinase A.

  3. LED-FISH: Fluorescence microscopy based on light emitting diodes for the molecular analysis of Her-2/neu oncogene amplification

    Directory of Open Access Journals (Sweden)

    Vollmer Ekkehard

    2008-12-01

    Full Text Available Abstract Light emitting diodes (LED, which are available as small monochromatic light sources with characteristic features such as maximum illumination power combined with minimum energy consumption and extremely long lifespan have already proved as a highly potential low-cost alternative for specific diagnostic applications in clinical medicine such as tuberculosis fluorescence microscopy. Likewise, the most reliable evaluation of Her-2/neu (c-erbB2 gene amplification, which has been established in the last few years for routine diagnosis in clinical pathology as determinant towards Herceptin-based treatment of patients with breast cancer, is based on fluorescence in situ hybridization (FISH and corresponding high priced fluorescence equipment. In order to test the possibility to utilize the advantages of low-cost LED technology on FISH analysis of c-erbB2 gene expression for routine diagnostic purposes, the applicability of a standard bright field Carl Zeiss Axiostar Plus microscope equipped with a Fraen AFTER* LED Fluorescence Microscope Kit for the detection of Her-2/neu gene signals was compared to an advanced Nikon Eclipse 80i fluorescence microscope in combination with a conventional 100W mercury vapor lamp. Both microscopes were fitted with the same Quicam FAST CCD digital camera to unequivocally compare the quality of the captured images. C-erbB2 gene expression was analyzed in 30 different human tissue samples of primary invasive breast cancer, following formalin fixation and subsequent paraffin-embedding. The Her2/neu gene signals (green were identifiable in the tumor cells in all cases and images of equal quality were captured under almost identical conditions by 480 nm (blue LED module equipped standard Axiostar microscope as compared to conventional fluorescence microscopy. In this first attempt, these monochromatic LED elements proved in principle to be suitable for the detection of Her-2/neu gene expression by FISH. Thus, our own

  4. Design and synthesis of a fluorescent molecular imprinted polymer for use in an optical fibre-based cocaine sensor

    Science.gov (United States)

    Wren, Stephen P.; Piletsky, Sergey A.; Karim, Kal; Gascoine, Paul; Lacey, Richard; Sun, Tong; Grattan, Kenneth T. V.

    2014-05-01

    Previously, we have developed chemical sensors using fibre optic-based techniques for the detection of Cocaine, utilising molecularly imprinted polymers (MIPs) containing fluorescein moieties as the signalling groups. Here, we report the computational design of a fluorophore which was incorporated into a MIP for the generation of a novel sensor that offers improved sensitivity for Cocaine with a detection range of 1-100μM. High selectivity for Cocaine over a suite of known Cocaine interferants (25μM) was also demonstrated by measuring changes in the intensity of fluorescence signals received from the sensor.

  5. Image reconstruction of fluorescent molecular tomography based on the tree structured Schur complement decomposition

    Directory of Open Access Journals (Sweden)

    Wang Jiajun

    2010-05-01

    Full Text Available Abstract Background The inverse problem of fluorescent molecular tomography (FMT often involves complex large-scale matrix operations, which may lead to unacceptable computational errors and complexity. In this research, a tree structured Schur complement decomposition strategy is proposed to accelerate the reconstruction process and reduce the computational complexity. Additionally, an adaptive regularization scheme is developed to improve the ill-posedness of the inverse problem. Methods The global system is decomposed level by level with the Schur complement system along two paths in the tree structure. The resultant subsystems are solved in combination with the biconjugate gradient method. The mesh for the inverse problem is generated incorporating the prior information. During the reconstruction, the regularization parameters are adaptive not only to the spatial variations but also to the variations of the objective function to tackle the ill-posed nature of the inverse problem. Results Simulation results demonstrate that the strategy of the tree structured Schur complement decomposition obviously outperforms the previous methods, such as the conventional Conjugate-Gradient (CG and the Schur CG methods, in both reconstruction accuracy and speed. As compared with the Tikhonov regularization method, the adaptive regularization scheme can significantly improve ill-posedness of the inverse problem. Conclusions The methods proposed in this paper can significantly improve the reconstructed image quality of FMT and accelerate the reconstruction process.

  6. Molecularly imprinted polymer based on MWCNT-QDs as fluorescent biomimetic sensor for specific recognition of target protein

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Zhaoqiang [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Annie Bligh, S.W. [Department of Life Sciences, Faculty of Science and Technology, University of Westminster, 115 New Cavendish Street, London W1W 6UW (United Kingdom); Tao, Lei; Quan, Jing [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Nie, Huali, E-mail: niehuali@dhu.edu.cn [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Zhu, Limin, E-mail: lzhu@dhu.edu.cn [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China); Gong, Xiao [College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620 (China)

    2015-03-01

    A novel molecularly imprinted optosensing material based on multi-walled carbon nanotube-quantum dots (MWCNT-QDs) has been designed and synthesized for its high selectivity, sensitivity and specificity in the recognition of a target protein bovine serum albumin (BSA). Molecularly imprinted polymer coated MWCNT-QDs using BSA as the template (BMIP-coated MWCNT-QDs) exhibits a fast mass-transfer speed with a response time of 25 min. It is found that the BSA as a target protein can significantly quench the luminescence of BMIP-coated MWCNT-QDs in a concentration-dependent manner that is best described by a Stern–Volmer equation. The K{sub SV} for BSA is much higher than bovine hemoglobin and lysozyme, implying a highly selective recognition of the BMIP-coated MWCNT-QDs to BSA. Under optimal conditions, the relative fluorescence intensity of BMIP-coated MWCNT-QDs decreases linearly with the increasing target protein BSA in the concentration range of 5.0 × 10{sup −7}–35.0 × 10{sup −7} M with a detection limit of 80 nM. - Highlights: • A novel fluorescent biomimetic sensor based on MWCNT-QDs was designed. • The sensor exhibited a fast mass-transfer speed with a response time of 25 min. • The sensor possessed a highly selective recognition to BSA.

  7. Synchrotron-based X-ray Fluorescence Microscopy in Conjunction with Nanoindentation to Study Molecular-Scale Interactions of Phenol–Formaldehyde in Wood Cell Walls

    Science.gov (United States)

    Joseph E. Jakes; Christopher G. Hunt; Daniel J. Yelle; Linda Lorenz; Kolby Hirth; Sophie-Charlotte Gleber; Stefan Vogt; Warren Grigsby; Charles R. Frihart

    2015-01-01

    Understanding and controlling molecular-scale interactions between adhesives and wood polymers are critical to accelerate the development of improved adhesives for advanced wood-based materials. The submicrometer resolution of synchrotron-based X-ray fluorescence microscopy (XFM) was found capable of mapping and quantifying infiltration of Br-labeled phenol−...

  8. A quencher-free molecular beacon design based on pyrene excimer fluorescence using pyrene-labeled UNA (unlocked nucleic acid)

    DEFF Research Database (Denmark)

    Karlsen, Kasper Kannegård; Okholm, Anders Hauge; Kjems, Jørgen

    2013-01-01

    A quencher-free molecular beacon capable of generating pyrene excimer fluorescence has been constructed using strategically positioned pyrene-UNA monomers. Hybridization of a fully complementary RNA target was accompanied by a pyrene excimer emission increase of more than 900%, and detection of RNA...

  9. A sensitive fluorescent nanosensor for chloramphenicol based on molecularly imprinted polymer-capped CdTe quantum dots.

    Science.gov (United States)

    Amjadi, Mohammad; Jalili, Roghayeh; Manzoori, Jamshid L

    2016-05-01

    A novel fluorescent nanosensor using molecularly imprinted silica nanospheres embedded CdTe quantum dots (CdTe@SiO2 @MIP) was developed for detection and quantification of chloramphenicol (CAP). The imprinted sensor was prepared by synthesis of molecularly imprinting polymer (MIP) on the hydrophilic CdTe quantum dots via reverse microemulsion method using small amounts of solvents. The resulting CdTe@SiO2 @MIP nanoparticles were characterized by fluorescence, UV-vis absorption and FT-IR spectroscopy and transmission electron microscopy. They preserved 48% of fluorescence quantum yield of the parent quantum dots. CAP remarkably quenched the fluorescence of prepared CdTe@SiO2 @MIP, probably via electron transfer mechanism. Under the optimal conditions, the relative fluorescence intensity of CdTe@SiO2 @MIP decreased with increasing CAP by a Stern-Volmer type equation in the concentration range of 40-500 µg L(-1). The corresponding detection limit was 5.0 µg L(-1). The intra-day and inter-day values for the precision of the proposed method were all <4%. The developed sensor had a good selectivity and was applied to determine CAP in spiked human and bovine serum and milk samples with satisfactory results. Copyright © 2015 John Wiley & Sons, Ltd.

  10. Bilayered near-infrared fluorescent nanoparticles based on low molecular weight PEI for tumor-targeted in vivo imaging

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hao; Li, Ke [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology (China); Xu, Liang [The University of Kansas, Department of Molecular Biosciences (United States); Wu, Daocheng, E-mail: wudaocheng@mail.xjtu.edu.cn [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology (China)

    2014-12-15

    To improve the tumor fluorescent imaging results in vivo, bilayered nanoparticles encapsulating a lipophilic near-infrared (NIR) fluorescent dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotri-carbocyanine iodide (DiR) were prepared using low molecular weight stearic acid-grafted polyethyleneimine and hyaluronic acid (DiR-PgSHA nanoparticles), which were investigated as a novel NIR fluorescent nano-probe for in vivo tumor-targeted optical imaging. These nanoparticles were characterized by transmission electron microscopy (TEM), infrared (IR) spectra, UV-visual absorption, and fluorescent emission spectra. Their cytotoxicity in vitro and hepatotoxicity in vivo were tested by MTT assay and histological study, respectively. In vivo NIR fluorescence imaging of the DiR-PgSHA nanoparticles was performed using a Carestream imaging system. The DiR-PgSHA nanoparticles were sphere shaped with a diameter of approximately 50 nm according to the TEM images. The DiR-PgSHA nanoparticles had a low cytotoxicity in vitro according to the MTT assay and low hepatotoxicity in vivo as determined in histological studies. The fluorescent emission of DiR-PgSHA nanoparticles was stable in pH values of 5–9 in solution, with only slight blue-shifts of the emission maxima at the basic pH range. The DiR-PgSHA nanoparticles exhibited a substantial tumor-targeting ability in the optical imaging with the use of tumor-bearing mice. These results demonstrated that the DiR-PgSHA nanoparticle is an excellent biocompatible nano-probe for in vivo tumor-targeted NIR fluorescence imaging with a potential for clinical applications.

  11. Bilayered near-infrared fluorescent nanoparticles based on low molecular weight PEI for tumor-targeted in vivo imaging

    International Nuclear Information System (INIS)

    Liu, Hao; Li, Ke; Xu, Liang; Wu, Daocheng

    2014-01-01

    To improve the tumor fluorescent imaging results in vivo, bilayered nanoparticles encapsulating a lipophilic near-infrared (NIR) fluorescent dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotri-carbocyanine iodide (DiR) were prepared using low molecular weight stearic acid-grafted polyethyleneimine and hyaluronic acid (DiR-PgSHA nanoparticles), which were investigated as a novel NIR fluorescent nano-probe for in vivo tumor-targeted optical imaging. These nanoparticles were characterized by transmission electron microscopy (TEM), infrared (IR) spectra, UV-visual absorption, and fluorescent emission spectra. Their cytotoxicity in vitro and hepatotoxicity in vivo were tested by MTT assay and histological study, respectively. In vivo NIR fluorescence imaging of the DiR-PgSHA nanoparticles was performed using a Carestream imaging system. The DiR-PgSHA nanoparticles were sphere shaped with a diameter of approximately 50 nm according to the TEM images. The DiR-PgSHA nanoparticles had a low cytotoxicity in vitro according to the MTT assay and low hepatotoxicity in vivo as determined in histological studies. The fluorescent emission of DiR-PgSHA nanoparticles was stable in pH values of 5–9 in solution, with only slight blue-shifts of the emission maxima at the basic pH range. The DiR-PgSHA nanoparticles exhibited a substantial tumor-targeting ability in the optical imaging with the use of tumor-bearing mice. These results demonstrated that the DiR-PgSHA nanoparticle is an excellent biocompatible nano-probe for in vivo tumor-targeted NIR fluorescence imaging with a potential for clinical applications

  12. A Turn-on Fluorescence Sensor for Heparin Detection Based on a Release of Taiwan Cobra Cardiotoxin from a DNA Aptamer or Adenosine-Based Molecular Beacon.

    Science.gov (United States)

    Shi, Yi-Jun; Wang, Liang-Jun; Lee, Yuan-Chin; Huang, Chia-Hui; Hu, Wan-Ping; Chang, Long-Sen

    2018-02-19

    This study presents two sensitive fluorescent assays for sensing heparin on the basis of the electrostatic interaction between heparin and Naja naja atra cardiotoxin 3 (CTX3). Owing to CTX3-induced folded structure of an adenosine-based molecular beacon (MB) or a DNA aptamer against CTX3, a reduction in the fluorescent signal of the aptamer or MB 5'-end labeled with carboxyfluorescein (FAM) and 3'-end labeled with 4-([4-(dimethylamino)phenyl]azo)-benzoic acid (DABCYL) was observed upon the addition of CTX3. The presence of heparin and formation of the CTX3-heparin complex caused CTX3 detachment from the MB or aptamer, and restoration of FAM fluorescence of the 5'-FAM-and-3'-DABCYL-labeled MB and aptamer was subsequently noted. Moreover, the detection of heparin with these CTX3-aptamer and CTX3-MB sensors showed high sensitivity and selectivity toward heparin over chondroitin sulfate and hyaluronic acid regardless of the presence of plasma. The limit of detection for heparin in plasma was determined to be 16 ng/mL and 15 ng/mL, respectively, at a signal-to-noise ratio of 3. This study validates the practical utility of the CTX3-aptamer and CTX3-MB systems for determining the concentration of heparin in a biological matrix.

  13. Molecular Imaging of β-Amyloid Plaques with Near-Infrared Boron Dipyrromethane (BODIPY-Based Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    Hiroyuki Watanabe

    2013-07-01

    Full Text Available The formation of β-amyloid (Aβ plaques is a critical neurodegenerative change in Alzheimer disease (AD. We designed and synthesized novel boron dipyrromethane (BODIPY-based Aβ probes (BAPs and evaluated their utility for near-infrared fluorescence imaging of Aβ plaques in the brain. In binding experiments in vitro, BAPs showed high affinity for synthetic Aβ aggregates (Kd = 18–149 nM. Furthermore, BAPs clearly stained Aβ plaques in sections of Tg2576 mice. In mouse brain tissue, BAPs showed sufficient uptake for optical imaging. In addition, ex vivo fluorescent staining of brain sections from Tg2576 mice after the injection of BAP-2 showed selective binding of Aβ plaques with little nonspecific binding. BAPs may be useful as a near-infrared fluorescent probe for imaging Aβ plaques.

  14. Fluorescence lifetime based bioassays

    Science.gov (United States)

    Meyer-Almes, Franz-Josef

    2017-12-01

    Fluorescence lifetime (FLT) is a robust intrinsic property and material constant of fluorescent matter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery, medical diagnostics and basic biological research. This distinct trend was mainly driven by improved and meanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. The first one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second even more dynamic trend is the significant expansion of assay methods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.

  15. A novel cyanide-selective colorimetric and fluorescent chemosensor: First molecular security keypad lock based on phosphotungstic acid and CN{sup −} inputs

    Energy Technology Data Exchange (ETDEWEB)

    Tavallali, Hossein, E-mail: Tavallali@pnu.ac.ir; Deilamy-Rad, Gohar; Parhami, Abolfath; Hasanli, Nahid

    2014-02-15

    Highlights: • Our probe is commercially available with good photo stability and high quantum yield. • Both color and fluorescence change with long emission wavelength in aqueous media. • Characteristics of an ON–OFF–ON fluorescence switch. • The simple receptor for CN{sup -} detection with low detection limit (≪WHO). • Mimic the function of a security keypad lock on sequential addition of PTA and CN{sup −}. -- Abstract: Rhodamine B (Rh{sub B}) an available dye has been developed as novel and efficient colorimetric and fluorometric chemosensor for cyanide ions in an absolutely aqueous media. The UV–vis absorption and fluorescent emission titrations experiments have been employed to study the sensing process. Rh{sub B} could act as an efficient “ON–OFF” fluorescent response for phosphotungstic acid (H{sub 3}PW{sub 12}O{sub 40} or PTA) based on an ion associate process. Also (Rh{sub B}{sup +}){sub 3}·PTA{sup 3−} could operate as an “OFF–ON” fluorescent sensor for cyanide anions based on a ligand substitution process. It has been identified as highly sensitive probe for CN{sup −} which responds at 0.3 and 0.04 μmol L{sup −1} concentration levels by absorption and fluorescent method respectively. Depending upon the sequence of addition of PTA and CN{sup −} ions into the solution, Rh{sub B} could be as a molecular security keypad lock with PTA and CN{sup −} inputs. The ionic inputs to new fluorophore have been mimicked as a superimposed electronic molecular keypad lock. The results were compared successfully (>96%) with the data of a spectrophotometry approved method (EPA 9014-1) for cyanide ions.

  16. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references

  17. Laser induced fluorescence of trapped molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references.

  18. Vibronic coupling in molecular crystals: A Franck-Condon Herzberg-Teller model of H-aggregate fluorescence based on quantum chemical cluster calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wykes, M., E-mail: mikewykes@gmail.com; Parambil, R.; Gierschner, J. [Madrid Institute for Advanced Studies, IMDEA Nanoscience, Calle Faraday 9, Campus Cantoblanco, 28049 Madrid (Spain); Beljonne, D. [Laboratory for Chemistry of Novel Materials, University of Mons, Place du Parc 20, 7000 Mons (Belgium)

    2015-09-21

    Here, we present a general approach to treating vibronic coupling in molecular crystals based on atomistic simulations of large clusters. Such clusters comprise model aggregates treated at the quantum chemical level embedded within a realistic environment treated at the molecular mechanics level. As we calculate ground and excited state equilibrium geometries and vibrational modes of model aggregates, our approach is able to capture effects arising from coupling to intermolecular degrees of freedom, absent from existing models relying on geometries and normal modes of single molecules. Using the geometries and vibrational modes of clusters, we are able to simulate the fluorescence spectra of aggregates for which the lowest excited state bears negligible oscillator strength (as is the case, e.g., ideal H-aggregates) by including both Franck-Condon (FC) and Herzberg-Teller (HT) vibronic transitions. The latter terms allow the adiabatic excited state of the cluster to couple with vibrations in a perturbative fashion via derivatives of the transition dipole moment along nuclear coordinates. While vibronic coupling simulations employing FC and HT terms are well established for single-molecules, to our knowledge this is the first time they are applied to molecular aggregates. Here, we apply this approach to the simulation of the low-temperature fluorescence spectrum of para-distyrylbenzene single-crystal H-aggregates and draw comparisons with coarse-grained Frenkel-Holstein approaches previously extensively applied to such systems.

  19. Protein recognition by a pattern-generating fluorescent molecular probe

    Science.gov (United States)

    Pode, Zohar; Peri-Naor, Ronny; Georgeson, Joseph M.; Ilani, Tal; Kiss, Vladimir; Unger, Tamar; Markus, Barak; Barr, Haim M.; Motiei, Leila; Margulies, David

    2017-12-01

    Fluorescent molecular probes have become valuable tools in protein research; however, the current methods for using these probes are less suitable for analysing specific populations of proteins in their native environment. In this study, we address this gap by developing a unimolecular fluorescent probe that combines the properties of small-molecule-based probes and cross-reactive sensor arrays (the so-called chemical 'noses/tongues'). On the one hand, the probe can detect different proteins by generating unique identification (ID) patterns, akin to cross-reactive arrays. On the other hand, its unimolecular scaffold and selective binding enable this ID-generating probe to identify combinations of specific protein families within complex mixtures and to discriminate among isoforms in living cells, where macroscopic arrays cannot access. The ability to recycle the molecular device and use it to track several binding interactions simultaneously further demonstrates how this approach could expand the fluorescent toolbox currently used to detect and image proteins.

  20. Enhancing molecular logic through modulation of temporal and spatial constraints with quantum dot-based systems that use fluorescent (Förster) resonance energy transfer

    Science.gov (United States)

    Claussen, Jonathan C.; Algar, W. Russ; Hildebrandt, Niko; Susumu, Kimihiro; Ancona, Mario G.; Medintz, Igor L.

    2013-10-01

    Luminescent semiconductor nanocrystals or quantum dots (QDs) contain favorable photonic properties (e.g., resistance to photobleaching, size-tunable PL, and large effective Stokes shifts) that make them well-suited for fluorescence (Förster) resonance energy transfer (FRET) based applications including monitoring proteolytic activity, elucidating the effects of nanoparticles-mediated drug delivery, and analyzing the spatial and temporal dynamics of cellular biochemical processes. Herein, we demonstrate how unique considerations of temporal and spatial constraints can be used in conjunction with QD-FRET systems to open up new avenues of scientific discovery in information processing and molecular logic circuitry. For example, by conjugating both long lifetime luminescent terbium(III) complexes (Tb) and fluorescent dyes (A647) to a single QD, we can create multiple FRET lanes that change temporally as the QD acts as both an acceptor and donor at distinct time intervals. Such temporal FRET modulation creates multi-step FRET cascades that produce a wealth of unique photoluminescence (PL) spectra that are well-suited for the construction of a photonic alphabet and photonic logic circuits. These research advances in bio-based molecular logic open the door to future applications including multiplexed biosensing and drug delivery for disease diagnostics and treatment.

  1. A Fluorescent Molecular Probe for the Detection of Hydrogen Based on Oxidative Addition Reactions with Crabtree-Type Hydrogenation Catalysts.

    Science.gov (United States)

    Kos, Pavlo; Plenio, Herbert

    2015-11-02

    A Crabtree-type Ir(I) complex tagged with a fluorescent dye (bodipy) was synthesized. The oxidative addition of H2 converts the weakly fluorescent Ir(I) complex (Φ=0.038) into a highly fluorescent Ir(III) species (Φ=0.51). This fluorogenic reaction can be utilized for the detection of H2 and to probe the oxidative addition step in the catalytic hydrogenation of olefins. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Winn, J.S.

    1980-10-01

    Laser induced fluoresence (LIF) spectra (laser excitation spectra) are conceptually among the most simple spectra to obtain. One need only confine a gaseous sample in a suitable container, direct a laser along one axis of the container, and monitor the sample's fluorescence at a right angle to the laser beam. As the laser wavelength is changed, the changes in fluorescence intensity map the absorption spectrum of the sample. (More precisely, only absorption to states which have a significant radiative decay component are monitored.) For ion spectroscopy, one could benefit in many ways by such an experiment. Most optical ion spectra have been observed by emission techniques, and, aside from the problems of spectral analysis, discharge emission methods often produce the spectra of many species, some of which may be unknown or uncertain. Implicit in the description of LIF given above is certainty as to the chemical identity of the carrier of the spectrum. This article describes a method by which the simplifying aspects of LIF can be extended to molecular ions

  3. Spectroscopic and TD-DFT studies on the dual mode fluorescent chemosensors based on pyrene thiosemicarbazones, and its application as molecular-scale logic devices

    Energy Technology Data Exchange (ETDEWEB)

    Basheer, Sabeel M. [Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015 (India); Willis, Anthony C. [Research School of Chemistry, The Australian National University, Canberra, ACT 2601 (Australia); Sreekanth, Anandaram, E-mail: sreekanth@nitt.edu [Department of Chemistry, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2017-03-15

    Two newly synthesised pyrene based molecules are hereby reported as molecular switches. The absorption and emission response for receptors with and without F{sup −}, CN{sup −} and Cu{sup 2+} ions can mimic multiple logic gate such as AND, NOR, XNOR, OR, XOR, INHIBITION and TRANSFER gates. The fluorescence reversibility was checked with the alternative addition of fluoride and calcium ions, which can be explained by the “Read-Erase-Read-Write” logic loop. The calculated binding constant value show PyBTSC is better chemosensor than PyCTSC, and the binding affinity is in the order of Cu{sup 2+}Г‹Ж’F{sup -}Г‹Ж’CN{sup −.} The detailed mechanism was investigated using DFT and TD-DFT calculations. The fluorescence quenching behaviour of receptor-F complex can be explained by PET mechanism along with ESPT process. The proton attached to the nitrogen which is adjacent to pyrene moiety is first make the hydrogen bond with fluoride ion at the excited state, which has confirmed by natural bond orbital (NBO) and potential energy surface (PES) analysis. - Graphical abstract: The newly synthesised thiocarbazone derivates used as an effective and selective colourimetric and “turn on” fluorescence sensor for copper ion and ‘turn off’ for fluoride and cyanide anion. The presence and absence of ions were considered as input signals and the corresponding absorption and emission responses were consired as output. The proton transfer from the nitrogen adjacent to pyrene moiety, and which takes place at the excited state (ESPT).

  4. An ultrasensitive and highly selective fluorescent and colorimetric chemosensor for citrate ions based on rhodamine B and its application as the first molecular security keypad lock based on phosphomolybdic acid and citrate inputs

    Energy Technology Data Exchange (ETDEWEB)

    Tavallali, Hossein, E-mail: Tavallali@pnu.ac.ir; Baezzat, Mohammad-Reza; Deilamy-Rad, Gohar; Parhami, Abolfath; Hasanli, Nahid

    2015-04-15

    Rhodamine B (Rh{sub B}) has been developed as novel and efficient colorimetric and fluorometric chemosensor for citrate ions (Cit{sup 3−}) in an absolutely aqueous media. The UV–vis absorption and fluorescent emission titrations experiments have been employed to study the sensing process. Rh{sub B} could act as an efficient “ON–OFF” fluorescent chemosensor for phosphomolybdic acid (PMA) based on an electron transfer (ET) process. Also (Rh{sub B}{sup +}){sub 3}.PMA{sup 3−} could operate as an “OFF–ON” fluorescent chemosensor for citrate ions based on a ligand substitution process. The chemosensor Rh{sub B} shows excellent fluorescence sensitivity and selectivity toward citrate in aqueous media, and displays ON–OFF–ON type fluorescence change with alternately adding PMA and citrate to the media along with reversible association–dissociation of the complex. The (Rh{sub B}{sup +}){sub 3}.PMA{sup 3−} can be applied to the quantification of citrate with a linear ranges covering from 0.053 to 0.83 and 0.08 to 1.6 µM by detection limits of 6.0 and 9.1 nM for fluorescence and colorimetric methods respectively. The keypad lock operation is particularly important, as the output of the system depends not only on the proper combination but also on the order of input signals, creating the correct password that can be used to “open” this molecular keypad lock through strong fluorescence emission at 575 nm. As a whole, its various logic gate properties may improve its impact for the development of new-generation “intelligence” digital devices. The ionic PMA and Cit{sup 3−} inputs to (Rh{sub B}{sup +}){sub 3}.PMA{sup 3−} have been mimicked as a superimposed electronic molecular keypad lock. Also indicates that Rh{sub B} is suitable for the detection of Cit{sup 3−} ions in the biological environment. - Highlights: • Our probe is commercially available with good photostability and high quantum yield. • Both color and fluorescence change

  5. Polarization of fluorescence: a probe of molecular autoionization

    International Nuclear Information System (INIS)

    Leroi, G.E.; Dehmer, J.L.; Parr, A.C.; Poliakoff, E.D.

    1983-01-01

    The polarization of fluorescence from excited-state molecular photoions provides a direct probe of the photoionization dynamics and the symmetry signatures of autoionizing resonances. Measurements on CO 2 and CS 2 are presented as examples

  6. Chemical point detection using differential fluorescence from molecularly imprinted polymers

    Science.gov (United States)

    Pestov, Dmitry; Anderson, John E.; Nelson, Jean; Tepper, Gary C.

    2004-12-01

    Fluorescence represents one of the most attractive approaches for chemical sensing due to the abundant light produced by most fluorophores, resulting in excellent detection sensitivity. However, the broad and overlapping emission spectra of target and background species have made it difficult to perform species identification in a field instrument because of the need to perform spectral decomposition and analysis. This paper describes a new chemical sensing strategy based on differential fluorescence measurements from molecularly imprinted polymers, which eliminates the need to perform any spectral analysis. Species identification is accomplished by measuring the differential light output from a pair of polymers-one imprinted to a target species and the other identical, but not imprinted. The imprinted polymer selectively concentrates the target molecule and controls the energy (wavelength) of the emitted fluorescence signal and the differential output eliminates common mode signals associated with non-specific background interference. Because no spectral analysis is required, the sensors can be made extremely small and require very little power. Preliminary performance parameters from a prototype sensor are presented and discussed.

  7. Fluorescent and colorimetric molecular recognition probe for hydrogen bond acceptors.

    Science.gov (United States)

    Pike, Sarah J; Hunter, Christopher A

    2017-11-22

    The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish self-consistent H-bond acceptor parameters (β) for benzoate, azide, chloride, thiocyanate anions, a series of phosphine oxides, phosphate ester, sulfoxide and a tertiary amide. The results demonstrate both the transferability of H-bond parameters between different solvents and the utility of the naphthol-based dual molecular recognition probe to exploit orthogonal spectroscopic techniques to determine the HBA properties of neutral and charged solutes. The benzoate anion is the strongest HBA studied with a β parameter of 15.4, and the neutral tertiary amide is the weakest H-bond acceptor investigated with a β parameter of 8.5. The H-bond acceptor strength of the azide anion is higher than that of chloride (12.8 and 12.2 respectively), and the thiocyanate anion has a β value of 10.8 and thus is a significantly weaker H-bond acceptor than both the azide and chloride anions.

  8. Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP).

    Science.gov (United States)

    Cipolloni, Marco; Kaleta, Jiří; Mašát, Milan; Dron, Paul I; Shen, Yongqiang; Zhao, Ke; Rogers, Charles T; Shoemaker, Richard K; Michl, Josef

    2015-04-23

    We examine the fluorescence anisotropy of rod-shaped guests held inside the channels of tris( o -phenylenedioxy)cyclotriphosphazene (TPP) host nanocrystals, characterized by powder X-ray diffraction and solid state NMR spectroscopy. We address two issues: (i) are light polarization measurements on an aqueous colloidal solution of TPP nanocrystals meaningful, or is depolarization by scattering excessive? (ii) Can measurements of the rotational mobility of the included guests be performed at low enough loading levels to suppress depolarization by intercrystallite energy transfer? We find that meaningful measurements are possible and demonstrate that the long axis of molecular rods included in TPP channels performs negligible vibrational motion.

  9. Molecular Iodine Fluorescence Using a Green Helium-Neon Laser

    Science.gov (United States)

    Williamson, J. Charles

    2011-01-01

    Excitation of molecular iodine vapor with a green (543.4 nm) helium-neon laser produces a fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application of standard evaluation techniques to the spectrum yields ground electronic-state molecular parameters in good agreement with literature…

  10. A molecular-sized optical logic circuit for digital modulation of a fluorescence signal

    Science.gov (United States)

    Nishimura, Takahiro; Tsuchida, Karin; Ogura, Yusuke; Tanida, Jun

    2018-03-01

    Fluorescence measurement allows simultaneous detection of multiple molecular species by using spectrally distinct fluorescence probes. However, due to the broad spectra of fluorescence emission, the multiplicity of fluorescence measurement is generally limited. To overcome this limitation, we propose a method to digitally modulate fluorescence output signals with a molecular-sized optical logic circuit by using optical control of fluorescence resonance energy transfer (FRET). The circuit receives a set of optical inputs represented with different light wavelengths, and then it switches high and low fluorescence intensity from a reporting molecule according to the result of the logic operation. By using combinational optical inputs in readout of fluorescence signals, the number of biomolecular species that can be identified is increased. To implement the FRET-based circuits, we designed two types of basic elements, YES and NOT switches. An YES switch produces a high-level output intensity when receiving a designated light wavelength input and a low-level intensity without the light irradiation. A NOT switch operates inversely to the YES switch. In experiments, we investigated the operation of the YES and NOT switches that receive a 532-nm light input and modulate the fluorescence intensity of Alexa Fluor 488. The experimental result demonstrates that the switches can modulate fluorescence signals according to the optical input.

  11. Fluorescent and Colorimetric Molecular Recognition Probe for Hydrogen Bond Acceptors

    OpenAIRE

    Pike, Sarah Jane; Hunter, Christopher Alexander

    2018-01-01

    The association constants for formation of 1 : 1 complexes between a H-bond donor, 1-naphthol, and a diverse range of charged and neutral H-bond acceptors have been measured using UV/vis absorption and fluorescence emission titrations. The performance of 1-naphthol as a dual colorimetric and fluorescent molecular recognition probe for determining the H-bond acceptor (HBA) parameters of charged and neutral solutes has been investigated in three solvents. The data were employed to establish sel...

  12. Laplacian manifold regularization method for fluorescence molecular tomography

    Science.gov (United States)

    He, Xuelei; Wang, Xiaodong; Yi, Huangjian; Chen, Yanrong; Zhang, Xu; Yu, Jingjing; He, Xiaowei

    2017-04-01

    Sparse regularization methods have been widely used in fluorescence molecular tomography (FMT) for stable three-dimensional reconstruction. Generally, ℓ1-regularization-based methods allow for utilizing the sparsity nature of the target distribution. However, in addition to sparsity, the spatial structure information should be exploited as well. A joint ℓ1 and Laplacian manifold regularization model is proposed to improve the reconstruction performance, and two algorithms (with and without Barzilai-Borwein strategy) are presented to solve the regularization model. Numerical studies and in vivo experiment demonstrate that the proposed Gradient projection-resolved Laplacian manifold regularization method for the joint model performed better than the comparative algorithm for ℓ1 minimization method in both spatial aggregation and location accuracy.

  13. Environmentally Sensitive Fluorescent Sensors Based on Synthetic Peptides

    Directory of Open Access Journals (Sweden)

    Laurence Choulier

    2010-03-01

    Full Text Available Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, based on peptidic receptors labeled with environmentally sensitive fluorophores. Fluorescent indicators based on synthetic peptides are highly interesting alternatives to protein-based sensors, since they can be synthesized chemically, are stable, and can be easily modified in a site-specific manner for fluorophore coupling and for immobilization on solid supports.

  14. Fluorescent sensors based on bacterial fusion proteins

    International Nuclear Information System (INIS)

    Mateu, Batirtze Prats; Pum, Dietmar; Sleytr, Uwe B; Toca-Herrera, José L; Kainz, Birgit

    2014-01-01

    Fluorescence proteins are widely used as markers for biomedical and technological purposes. Therefore, the aim of this project was to create a fluorescent sensor, based in the green and cyan fluorescent protein, using bacterial S-layers proteins as scaffold for the fluorescent tag. We report the cloning, expression and purification of three S-layer fluorescent proteins: SgsE-EGFP, SgsE-ECFP and SgsE-13aa-ECFP, this last containing a 13-amino acid rigid linker. The pH dependence of the fluorescence intensity of the S-layer fusion proteins, monitored by fluorescence spectroscopy, showed that the ECFP tag was more stable than EGFP. Furthermore, the fluorescent fusion proteins were reassembled on silica particles modified with cationic and anionic polyelectrolytes. Zeta potential measurements confirmed the particle coatings and indicated their colloidal stability. Flow cytometry and fluorescence microscopy showed that the fluorescence of the fusion proteins was pH dependent and sensitive to the underlying polyelectrolyte coating. This might suggest that the fluorescent tag is not completely exposed to the bulk media as an independent moiety. Finally, it was found out that viscosity enhanced the fluorescence intensity of the three fluorescent S-layer proteins. (paper)

  15. RBAP, a Rhodamine B-Based Derivative: Synthesis, Crystal Structure Analysis, Molecular Simulation, and Its Application as a Selective Fluorescent Chemical Sensor for Sn2+

    Directory of Open Access Journals (Sweden)

    Xiaofeng Bao

    2014-06-01

    Full Text Available A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95 solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+.

  16. RBAP, a Rhodamine B-Based Derivative: Synthesis, Crystal Structure Analysis, Molecular Simulation, and Its Application as a Selective Fluorescent Chemical Sensor for Sn2+

    OpenAIRE

    Xiaofeng Bao; Xiaowei Cao; Xuemei Nie; Yanyan Jin; Baojing Zhou

    2014-01-01

    A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP) was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+.

  17. A parallel adaptive finite element simplified spherical harmonics approximation solver for frequency domain fluorescence molecular imaging

    International Nuclear Information System (INIS)

    Lu Yujie; Zhu Banghe; Rasmussen, John C; Sevick-Muraca, Eva M; Shen Haiou; Wang Ge

    2010-01-01

    Fluorescence molecular imaging/tomography may play an important future role in preclinical research and clinical diagnostics. Time- and frequency-domain fluorescence imaging can acquire more measurement information than the continuous wave (CW) counterpart, improving the image quality of fluorescence molecular tomography. Although diffusion approximation (DA) theory has been extensively applied in optical molecular imaging, high-order photon migration models need to be further investigated to match quantitation provided by nuclear imaging. In this paper, a frequency-domain parallel adaptive finite element solver is developed with simplified spherical harmonics (SP N ) approximations. To fully evaluate the performance of the SP N approximations, a fast time-resolved tetrahedron-based Monte Carlo fluorescence simulator suitable for complex heterogeneous geometries is developed using a convolution strategy to realize the simulation of the fluorescence excitation and emission. The validation results show that high-order SP N can effectively correct the modeling errors of the diffusion equation, especially when the tissues have high absorption characteristics or when high modulation frequency measurements are used. Furthermore, the parallel adaptive mesh evolution strategy improves the modeling precision and the simulation speed significantly on a realistic digital mouse phantom. This solver is a promising platform for fluorescence molecular tomography using high-order approximations to the radiative transfer equation.

  18. Ratiometric fluorescent receptors for both Zn2+ and H2PO4(-) ions based on a pyrenyl-linked triazole-modified homooxacalix[3]arene: a potential molecular traffic signal with an R-S latch logic circuit.

    Science.gov (United States)

    Ni, Xin-long; Zeng, Xi; Redshaw, Carl; Yamato, Takehiko

    2011-07-15

    A ratiometric fluorescent receptor with a C(3) symmetric structure based on a pyrene-linked triazole-modified homooxacalix[3]arene (L) was synthesized and characterized. This system exhibited an interesting ratiometric detection signal output for targeting cations and anions through switching the excimer emission of pyrene from the "on-off" to the "off-on" type in neutral solution. (1)H NMR titration results suggested that the Zn(2+) center of receptor L·Zn(2+) provided an excellent pathway of organizing anion binding groups for optimal host-guest interactions. It is thus believed that this receptor has potential application in sensing, detection, and recognition of both Zn(2+) and H(2)PO(4)(-) ions with different optical signals. In addition, the fluorescence emission changes by the inputs of Zn(2+) and H(2)PO(4)(-) ions can be viewed as a combinational R-S latch logic circuit at the molecular level.

  19. Gastrin-releasing peptide receptor-targeted gadolinium oxide-based multifunctional nanoparticles for dual magnetic resonance/fluorescent molecular imaging of prostate cancer

    Directory of Open Access Journals (Sweden)

    Cui DT

    2017-09-01

    Full Text Available Danting Cui,1 Xiaodan Lu,1 Chenggong Yan,1 Xiang Liu,1 Meirong Hou,1 Qi Xia,2 Yikai Xu,1 Ruiyuan Liu2,3 1Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, People’s Republic of China; 2School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, People’s Republic of China; 3School of Biomedical Engineering, Southern Medical University, Guangzhou, People’s Republic of China Abstract: Bombesin (BBN, an analog of gastrin-releasing peptide (GRP, specifically binds to GRP receptors, which are overexpressed in human prostate cancer (PC. Here, we synthesized a BBN-modified gadolinium oxide (Gd2O3 nanoprobe containing fluorescein (Gd2O3-5(6-carboxyfluorescein [FI]-polyethylene glycol [PEG]-BBN for targeted magnetic resonance (MR/optical dual-modality imaging of PC. The Gd2O3-FI-PEG-BBN nanoparticles exhibited a relatively uniform particle size with an average diameter of 52.3 nm and spherical morphology as depicted by transmission electron microscopy. The longitudinal relaxivity (r1 of Gd2O3-FI-PEG-BBN (r1 =4.23 mM–1s–1 is comparable to that of clinically used Magnevist (Gd-DTPA. Fluorescence microscopy and in vitro cellular MRI demonstrated GRP receptor-specific and enhanced cellular uptake of the Gd2O3-FI-PEG-BBN in PC-3 tumor cells. Moreover, Gd2O3-FI-PEG-BBN showed more remarkable contrast enhancement than the corresponding nontargeted Gd2O3-FI-PEG according to in vivo MRI and fluorescent imaging. Tumor immunohistochemical analysis further demonstrated improved accumulation of the targeted nanoprobe in tumors. BBN-conjugated Gd2O3 may be a promising nanoplatform for simultaneous GRP receptor-targeted molecular cancer diagnosis and antitumor drug delivery in future clinical applications. Keywords: magnetic resonance imaging, gadolinium oxide, bombesin, gastrin-releasing peptide receptor, molecular imaging

  20. Environment-sensitive behavior of fluorescent molecular rotors

    Directory of Open Access Journals (Sweden)

    Theodorakis Emmanuel A

    2010-09-01

    Full Text Available Abstract Molecular rotors are a group of fluorescent molecules that form twisted intramolecular charge transfer (TICT states upon photoexcitation. When intramolecular twisting occurs, the molecular rotor returns to the ground state either by emission of a red-shifted emission band or by nonradiative relaxation. The emission properties are strongly solvent-dependent, and the solvent viscosity is the primary determinant of the fluorescent quantum yield from the planar (non-twisted conformation. This viscosity-sensitive behavior gives rise to applications in, for example, fluid mechanics, polymer chemistry, cell physiology, and the food sciences. However, the relationship between bulk viscosity and the molecular-scale interaction of a molecular rotor with its environment are not fully understood. This review presents the pertinent theories of the rotor-solvent interaction on the molecular level and how this interaction leads to the viscosity-sensitive behavior. Furthermore, current applications of molecular rotors as microviscosity sensors are reviewed, and engineering aspects are presented on how measurement accuracy and precision can be improved.

  1. Fluorescence Molecular Tomography: Principles and Potential for Pharmaceutical Research

    Directory of Open Access Journals (Sweden)

    Florian Stuker

    2011-04-01

    Full Text Available Fluorescence microscopic imaging is widely used in biomedical research to study molecular and cellular processes in cell culture or tissue samples. This is motivated by the high inherent sensitivity of fluorescence techniques, the spatial resolution that compares favorably with cellular dimensions, the stability of the fluorescent labels used and the sophisticated labeling strategies that have been developed for selectively labeling target molecules. More recently, two and three-dimensional optical imaging methods have also been applied to monitor biological processes in intact biological organisms such as animals or even humans. These whole body optical imaging approaches have to cope with the fact that biological tissue is a highly scattering and absorbing medium. As a consequence, light propagation in tissue is well described by a diffusion approximation and accurate reconstruction of spatial information is demanding. While in vivo optical imaging is a highly sensitive method, the signal is strongly surface weighted, i.e., the signal detected from the same light source will become weaker the deeper it is embedded in tissue, and strongly depends on the optical properties of the surrounding tissue. Derivation of quantitative information, therefore, requires tomographic techniques such as fluorescence molecular tomography (FMT, which maps the three-dimensional distribution of a fluorescent probe or protein concentration. The combination of FMT with a structural imaging method such as X-ray computed tomography (CT or Magnetic Resonance Imaging (MRI will allow mapping molecular information on a high definition anatomical reference and enable the use of prior information on tissue’s optical properties to enhance both resolution and sensitivity. Today many of the fluorescent assays originally developed for studies in cellular systems have been successfully translated for experimental studies in animals. The opportunity of monitoring molecular

  2. Molecular engineering and fluorescence for the detection of toxic cations

    International Nuclear Information System (INIS)

    Souchon, V.

    2007-11-01

    This work is a part of the 'Toxicologie Nucleaire Environnementale' program which aims at studying the effects on the living of heavy metals or radionuclides involved in nuclear industry. Most particularly, it deals with the design of new fluorescent sensors for the selective detection of Pb 2+ , Cd 2+ and Cs + in biological media. Several fluorescent calixarenes possessing nitrogen atoms were synthesized and their properties as potential lead sensors were investigated. One of them could be used in experimental conditions close to biological media and new target compounds with amide functional groups were proposed. Many approaches were considered for the design of selective fluorescent sensors for cadmium. On the basis of literature results, many chelating compounds incorporating sulfur atoms were synthesized but showed no significant affinity towards cadmium. On the opposite, compounds functionalized with several pyridine-2'-yl-1,2,3-triazol fluorescent moieties linked to a β-cyclodextrin or a calix[4]arene showed good affinity for cadmium in methanol, but the selectivity was found to be insufficient. In contrast, very satisfying results in terms of both selectivity and sensitivity could be obtained with the commercial calcium sensor Rhod-5N in an aqueous medium at neutral pH. Lastly, micromolar detection limits for the selective detection of caesium were reached in an aqueous medium at neutral pH thanks to a new sulfonated fluorescent calixarene with two appended crown-ethers. An original complexation mechanism was proposed and validated by molecular modelling (DFT). (author)

  3. Fluorescence excitation studies of molecular photoionization in external electric fields

    International Nuclear Information System (INIS)

    Poliakoff, E.D.; Dehmer, J.L.; Parr, A.C.; Leroi, G.E.

    1985-01-01

    Using molecular nitrogen as an example, we show that fluorescence excitation spectroscopy can be used to measure partial photoionization cross sections of free molecules in external electric fields. The production of the N 2 + (B 2 Σ/sub u/ + ) state was studied and the threshold for this process was found to shift linearly with the square root of the applied field. This behavior is compared with the hydrogenic case and with previously studied systems

  4. In Vivo Diffuse Optical Tomography and Fluorescence Molecular Tomography

    Directory of Open Access Journals (Sweden)

    Mingze Li

    2010-01-01

    Full Text Available Diffuse optical tomography (DOT and fluorescence molecular tomography (FMT are two attractive imaging techniques for in vivo physiological and psychological research. They have distinct advantages such as non-invasiveness, non-ionizing radiation, high sensitivity and longitudinal monitoring. This paper reviews the key components of DOT and FMT. Light propagation model, mathematical reconstruction algorithm, imaging instrumentation and medical applications are included. Future challenges and perspective on optical tomography are discussed.

  5. Fluorescence-Raman Dual Modal Endoscopic System for Multiplexed Molecular Diagnostics

    Science.gov (United States)

    Jeong, Sinyoung; Kim, Yong-Il; Kang, Homan; Kim, Gunsung; Cha, Myeong Geun; Chang, Hyejin; Jung, Kyung Oh; Kim, Young-Hwa; Jun, Bong-Hyun; Hwang, Do Won; Lee, Yun-Sang; Youn, Hyewon; Lee, Yoon-Sik; Kang, Keon Wook; Lee, Dong Soo; Jeong, Dae Hong

    2015-03-01

    Optical endoscopic imaging, which was recently equipped with bioluminescence, fluorescence, and Raman scattering, allows minimally invasive real-time detection of pathologies on the surface of hollow organs. To characterize pathologic lesions in a multiplexed way, we developed a dual modal fluorescence-Raman endomicroscopic system (FRES), which used fluorescence and surface-enhanced Raman scattering nanoprobes (F-SERS dots). Real-time, in vivo, and multiple target detection of a specific cancer was successful, based on the fast imaging capability of fluorescence signals and the multiplex capability of simultaneously detected SERS signals using an optical fiber bundle for intraoperative endoscopic system. Human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) on the breast cancer xenografts in a mouse orthotopic model were successfully detected in a multiplexed way, illustrating the potential of FRES as a molecular diagnostic instrument that enables real-time tumor characterization of receptors during routine endoscopic procedures.

  6. A small molecular pH-dependent fluorescent probe for cancer cell imaging in living cell.

    Science.gov (United States)

    Ma, Junbao; Li, Wenqi; Li, Juanjuan; Shi, Rongguang; Yin, Gui; Wang, Ruiyong

    2018-05-15

    A novel pH-dependent two-photon fluorescent molecular probe ABMP has been prepared based on the fluorophore of 2, 4, 6-trisubstituted pyridine. The probe has an absorption wavelength at 354 nm and corresponding emission wavelength at 475 nm with the working pH range from 2.20 to 7.00, especially owning a good liner response from pH = 2.40 to pH = 4.00. ABMP also has excellent reversibility, photostability and selectivity which promotes its ability in analytical application. The probe can be excited with a two-photon fluorescence microscopy and the fluorescence cell imaging indicated that the probe can distinguish Hela cancer cells out of normal cells with a two-photon fluorescence microscopy which suggested its potential application in tumor cell detection. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. The Value of 5-Aminolevulinic Acid in Low-grade Gliomas and High-grade Gliomas Lacking Glioblastoma Imaging Features: An Analysis Based on Fluorescence, Magnetic Resonance Imaging, 18F-Fluoroethyl Tyrosine Positron Emission Tomography, and Tumor Molecular Factors.

    Science.gov (United States)

    Jaber, Mohammed; Wölfer, Johannes; Ewelt, Christian; Holling, Markus; Hasselblatt, Martin; Niederstadt, Thomas; Zoubi, Tarek; Weckesser, Matthias; Stummer, Walter

    2016-03-01

    Approximately 20% of grade II and most grade III gliomas fluoresce after 5-aminolevulinic acid (5-ALA) application. Conversely, approximately 30% of nonenhancing gliomas are actually high grade. The aim of this study was to identify preoperative factors (ie, age, enhancement, 18F-fluoroethyl tyrosine positron emission tomography [F-FET PET] uptake ratios) for predicting fluorescence in gliomas without typical glioblastomas imaging features and to determine whether fluorescence will allow prediction of tumor grade or molecular characteristics. Patients harboring gliomas without typical glioblastoma imaging features were given 5-ALA. Fluorescence was recorded intraoperatively, and biopsy specimens collected from fluorescing tissue. World Health Organization (WHO) grade, Ki-67/MIB-1 index, IDH1 (R132H) mutation status, O-methylguanine DNA methyltransferase (MGMT) promoter methylation status, and 1p/19q co-deletion status were assessed. Predictive factors for fluorescence were derived from preoperative magnetic resonance imaging and F-FET PET. Classification and regression tree analysis and receiver-operating-characteristic curves were generated for defining predictors. Of 166 tumors, 82 were diagnosed as WHO grade II, 76 as grade III, and 8 as glioblastomas grade IV. Contrast enhancement, tumor volume, and F-FET PET uptake ratio >1.85 predicted fluorescence. Fluorescence correlated with WHO grade (P fluorescing grade III gliomas was higher than in nonfluorescing tumors, whereas in fluorescing and nonfluorescing grade II tumors, no differences were noted. Age, tumor volume, and F-FET PET uptake are factors predicting 5-ALA-induced fluorescence in gliomas without typical glioblastoma imaging features. Fluorescence was associated with an increased Ki-67/MIB-1 index and high-grade pathology. Whether fluorescence in grade II gliomas identifies a subtype with worse prognosis remains to be determined.

  8. Cyanine-based probe\\tag-peptide pair fluorescence protein imaging and fluorescence protein imaging methods

    Science.gov (United States)

    Mayer-Cumblidge, M. Uljana; Cao, Haishi

    2013-01-15

    A molecular probe comprises two arsenic atoms and at least one cyanine based moiety. A method of producing a molecular probe includes providing a molecule having a first formula, treating the molecule with HgOAc, and subsequently transmetallizing with AsCl.sub.3. The As is liganded to ethanedithiol to produce a probe having a second formula. A method of labeling a peptide includes providing a peptide comprising a tag sequence and contacting the peptide with a biarsenical molecular probe. A complex is formed comprising the tag sequence and the molecular probe. A method of studying a peptide includes providing a mixture containing a peptide comprising a peptide tag sequence, adding a biarsenical probe to the mixture, and monitoring the fluorescence of the mixture.

  9. Handheld Fluorescence Microscopy based Flow Analyzer.

    Science.gov (United States)

    Saxena, Manish; Jayakumar, Nitin; Gorthi, Sai Siva

    2016-03-01

    Fluorescence microscopy has the intrinsic advantages of favourable contrast characteristics and high degree of specificity. Consequently, it has been a mainstay in modern biological inquiry and clinical diagnostics. Despite its reliable nature, fluorescence based clinical microscopy and diagnostics is a manual, labour intensive and time consuming procedure. The article outlines a cost-effective, high throughput alternative to conventional fluorescence imaging techniques. With system level integration of custom-designed microfluidics and optics, we demonstrate fluorescence microscopy based imaging flow analyzer. Using this system we have imaged more than 2900 FITC labeled fluorescent beads per minute. This demonstrates high-throughput characteristics of our flow analyzer in comparison to conventional fluorescence microscopy. The issue of motion blur at high flow rates limits the achievable throughput in image based flow analyzers. Here we address the issue by computationally deblurring the images and show that this restores the morphological features otherwise affected by motion blur. By further optimizing concentration of the sample solution and flow speeds, along with imaging multiple channels simultaneously, the system is capable of providing throughput of about 480 beads per second.

  10. Counting constituents in molecular complexes by fluorescence photon antibunching

    Energy Technology Data Exchange (ETDEWEB)

    Fore, S; Laurence, T; Hollars, C; Huser, T

    2007-04-17

    Modern single molecule fluorescence microscopy offers new, highly quantitative ways of studying the systems biology of cells while keeping the cells healthy and alive in their natural environment. In this context, a quantum optical technique, photon antibunching, has found a small niche in the continuously growing applications of single molecule techniques to small molecular complexes. Here, we review some of the most recent applications of photon antibunching in biophotonics, and we provide a guide for how to conduct photon antibunching experiments at the single molecule level by applying techniques borrowed from time-correlated single photon counting. We provide a number of new examples for applications of photon antibunching to the study of multichromophoric molecules and small molecular complexes.

  11. Fluorescence quantum yield measurements of fluorescent proteins: a laboratory experiment for a biochemistry or molecular biophysics laboratory course.

    Science.gov (United States)

    Wall, Kathryn P; Dillon, Rebecca; Knowles, Michelle K

    2015-01-01

    Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts absorbed photons into emitted photons and it is necessary to know for assessing what fluorescent protein is the most appropriate for a particular application. In this work, we have designed an upper-level, biochemistry laboratory experiment where students measure the fluorescence quantum yields of fluorescent proteins relative to a standard organic dye. Four fluorescent protein variants, enhanced cyan fluorescent protein (ECFP), enhanced green fluorescent protein (EGFP), mCitrine, and mCherry, were used, however the methods described are useful for the characterization of any fluorescent protein or could be expanded to fluorescent quantum yield measurements of organic dye molecules. The laboratory is designed as a guided inquiry project and takes two, 4 hr laboratory periods. During the first day students design the experiment by selecting the excitation wavelength, choosing the standard, and determining the concentration needed for the quantum yield experiment that takes place in the second laboratory period. Overall, this laboratory provides students with a guided inquiry learning experience and introduces concepts of fluorescence biophysics into a biochemistry laboratory curriculum. © 2014 The International Union of Biochemistry and Molecular Biology.

  12. Novel biosensor system model based on fluorescence quenching by a fluorescent streptavidin and carbazole-labeled biotin.

    Science.gov (United States)

    Zhu, Xianwei; Shinohara, Hiroaki; Miyatake, Ryuta; Hohsaka, Takahiro

    2016-10-01

    In the present study, a novel molecular biosensor system model was designed by using a couple of the fluorescent unnatural mutant streptavidin and the carbazole-labeled biotin. BODIPY-FL-aminophenylalanine (BFLAF), a fluorescent unnatural amino acid was position-specifically incorporated into Trp120 position of streptavidin by four-base codon method. On the other hand, carbazole-labeled biotin was synthesized as a quencher for the fluorescent Trp120BFLAF mutant streptavidin. The fluorescence of fluorescent Trp120BFLAF mutant streptavidin was decreased as we expected when carbazole-labeled biotin was added into the mutant streptavidin solution. Furthermore, the fluorescence decrease of Trp120BFLAF mutant streptavidin with carbazole-labeled biotin (100 nM) was recovered by the competitive addition of natural biotin. This result demonstrated that by measuring the fluorescence quenching and recovery, a couple of the fluorescent Trp120BFLAF mutant streptavidin and the carbazole-labeled biotin were successfully applicable for quantification of free biotin as a molecular biosensor system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Fluorescence-Based Multiplex Protein Detection Using Optically Encoded Microbeads

    Directory of Open Access Journals (Sweden)

    Dae Hong Jeong

    2012-03-01

    Full Text Available Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based multiplex detection techniques. Among the various techniques for high-throughput protein screening, optically-encoded beads combined with fluorescence-based target monitoring have great advantages over the planar array-based multiplexing assays. This review discusses recent developments of analytical methods of screening protein molecules on microbead-based platforms. These include various strategies such as barcoded microbeads, molecular beacon-based techniques, and surface-enhanced Raman scattering-based techniques. Their applications for label-free protein detection are also addressed. Especially, the optically-encoded beads such as multilayer fluorescence beads and SERS-encoded beads are successful for generating a large number of coding.

  14. Nanoplatform-based molecular imaging

    National Research Council Canada - National Science Library

    Chen, Xiaoyuan

    2011-01-01

    "Nanoplathform-Based Molecular Imaging provides rationale for using nanoparticle-based probes for molecular imaging, then discusses general strategies for this underutilized, yet promising, technology...

  15. Molecular engineering of two-photon fluorescent probes for bioimaging applications

    Science.gov (United States)

    Liu, Hong-Wen; Liu, Yongchao; Wang, Peng; Zhang, Xiao-Bing

    2017-03-01

    During the past two decades, two-photon microscopy (TPM), which utilizes two near-infrared photons as the excitation source, has emerged as a novel, attractive imaging tool for biological research. Compared with one-photon microscopy, TPM offers several advantages, such as lowering background fluorescence in living cells and tissues, reducing photodamage to biosamples, and a photobleaching phenomenon, offering better 3D spatial localization, and increasing penetration depth. Small-molecule-based two-photon fluorescent probes have been well developed for the detection and imaging of various analytes in biological systems. In this review, we will give a general introduction of molecular engineering of two-photon fluorescent probes based on different fluorescence response mechanisms for bioimaging applications during the past decade. Inspired by the desired advantages of small-molecule two-photon fluorescent probes in biological imaging applications, we expect that more attention will be devoted to the development of new two-photon fluorophores and applications of TPM in areas of bioanalysis and disease diagnosis.

  16. Fluorescent Biosensors Based on Single-Molecule Counting.

    Science.gov (United States)

    Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

    2016-09-20

    Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

  17. Early Detection of Breast Cancer by Fluorescence Molecular Tomography

    National Research Council Canada - National Science Library

    Ntziachristos, Vasilis

    2007-01-01

    .... We have successfully completed all goals and achieved the three major aims of the proposal, i.e. i) the development of appropriate fluorescence imaging methods for highly reliable and quantitative fluorescence imaging ii...

  18. Molecular Viscosity Sensors with Two Rotators for Optimizing the Fluorescence Intensity-Contrast Trade-Off.

    Science.gov (United States)

    Lee, Seung-Chul; Lee, Chang-Lyoul; Heo, Jeongyun; Jeong, Chan-Uk; Lee, Gyeong-Hui; Kim, Sehoon; Yoon, Woojin; Yun, Hoseop; Park, Sung O; Kwak, Sang Kyu; Park, Sung-Ha; Kwon, O-Pil

    2018-02-26

    A series of fluorescent molecular rotors obtained by introducing two rotational groups ("rotators"), which exhibit different rotational and electron-donating abilities, are discussed. Whereas the control molecular rotor, PH, includes a single rotator (the widely used phenyl group), the PO molecular rotors consist of two rotators (a phenyl group and an alkoxy group), which exhibit simultaneous strongly electron-donating and easy rotational abilities. Compared with the control rotor PH, PO molecular rotors exhibited one order of magnitude higher quantum yield (fluorescence intensity) and simultaneously exhibited significantly higher fluorescence contrast. These properties are directly related to the strong electron-donating ability and low energy barrier of rotation of the alkoxy group, as confirmed by dynamic fluorescence experiments and quantum chemical calculations. The PO molecular rotors exhibited two fluorescence relaxation pathways, whereas the PH molecular rotor exhibited a single fluorescence relaxation pathway. Cellular fluorescence imaging with PO molecular rotors for mapping cellular viscosity was successfully demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Near-Infrared Fluorescence Imaging Guided Therapy: Molecular Beacon-Based Photosensitizers Triggered by Breast Cancer-Specific mRNA

    Science.gov (United States)

    2007-05-01

    experiments was first dissolved in dimethylsulfoxide ( DMSO ) (no more than 0.5% of total volume) and then diluted with 0.1% Tween 80 in DNA-water, filtered...Abbreviations: BSA, bovine serum albumin; DCM, dichlo- romethane; DIPEA, diisopropylethylamine; DMSO , dimethylsulfoxide ; EDTA...example, the standard aqueous solution-based oligonucleotide conjugation protocol, even with the help of organic solvents (ACN), can not be used for

  20. Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP)

    Czech Academy of Sciences Publication Activity Database

    Cipolloni, Marco; Kaleta, Jiří; Mašát, Milan; Dron, P. I.; Shen, Y.; Zhao, K.; Rogers, C. T.; Shoemaker, R. K.; Michl, Josef

    2015-01-01

    Roč. 119, č. 16 (2015), s. 8805-8820 ISSN 1932-7447 EU Projects: European Commission(XE) 227756 - DIPOLAR ROTOR ARRAY Institutional support: RVO:61388963 Keywords : compound based approach * stretched polyethylene * solvent invironment Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.509, year: 2015 http://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.5b01960

  1. Dynamic fluorescence imaging with molecular agents for cancer detection

    Science.gov (United States)

    Kwon, Sun Kuk

    Non-invasive dynamic optical imaging of small animals requires the development of a novel fluorescence imaging modality. Herein, fluorescence imaging is demonstrated with sub-second camera integration times using agents specifically targeted to disease markers, enabling rapid detection of cancerous regions. The continuous-wave fluorescence imaging acquires data with an intensified or an electron-multiplying charge-coupled device. The work presented in this dissertation (i) assessed dose-dependent uptake using dynamic fluorescence imaging and pharmacokinetic (PK) models, (ii) evaluated disease marker availability in two different xenograft tumors, (iii) compared the impact of autofluorescence in fluorescence imaging of near-infrared (NIR) vs. red light excitable fluorescent contrast agents, (iv) demonstrated dual-wavelength fluorescence imaging of angiogenic vessels and lymphatics associated with a xenograft tumor model, and (v) examined dynamic multi-wavelength, whole-body fluorescence imaging with two different fluorescent contrast agents. PK analysis showed that the uptake of Cy5.5-c(KRGDf) in xenograft tumor regions linearly increased with doses of Cy5.5-c(KRGDf) up to 1.5 nmol/mouse. Above 1.5 nmol/mouse, the uptake did not increase with doses, suggesting receptor saturation. Target to background ratio (TBR) and PK analysis for two different tumor cell lines showed that while Kaposi's sarcoma (KS1767) exhibited early and rapid uptake of Cy5.5-c(KRGDf), human melanoma tumors (M21) had non-significant TBR differences and early uptake rates similar to the contralateral normal tissue regions. The differences may be due to different compartment location of the target. A comparison of fluorescence imaging with NIR vs. red light excitable fluorescent dyes demonstrates that NIR dyes are associated with less background signal, enabling rapid tumor detection. In contrast, animals injected with red light excitable fluorescent dyes showed high autofluorescence. Dual

  2. A fluorescence switch based on a controllable photochromic naphthopyran group

    International Nuclear Information System (INIS)

    Chen Lizhen; Wang Guang; Zhao Xiancai

    2011-01-01

    A fluorescence switch based on photoisomerization of naphthopyran (NP) has been designed by employing 2-(pyridin-2-yl)-benzimidazole (BPI) and the naphthopyran containing two pyran rings (NP) as fluorescent dye and photochromic compound, respectively. The fluorescence switch of benzimidazole derivative can be modulated either by controlling the irradiation time of UV light or by adjusting the amount ratio of fluorescent benzimidazole derivative to photochromic naphthopyran in both solution and polymethyl methacrylate (PMMA) film. The experimental results indicated that the decrease of fluorescence intensity of benzimidazole derivative is attributed to the interaction of benzimidazole with naphthopyran. - Highlights: → Naphthopyran was first used to fabricate fluorescence switch with benzimidazole derivative. → Fluorescence intensity can be modulated by controlling the UV irradiation time. → Fluorescence intensity can be adjusted by changing the ratio of benzimidazole derivative to naphthopyran. → Decrease of fluorescence intensity is attributed to the interaction of benzimidazole derivative and naphthopyran.

  3. A label-free, fluorescence based assay for microarray

    Science.gov (United States)

    Niu, Sanjun

    DNA chip technology has drawn tremendous attention since it emerged in the mid 90's as a method that expedites gene sequencing by over 100-fold. DNA chip, also called DNA microarray, is a combinatorial technology in which different single-stranded DNA (ssDNA) molecules of known sequences are immobilized at specific spots. The immobilized ssDNA strands are called probes. In application, the chip is exposed to a solution containing ssDNA of unknown sequence, called targets, which are labeled with fluorescent dyes. Due to specific molecular recognition among the base pairs in the DNA, the binding or hybridization occurs only when the probe and target sequences are complementary. The nucleotide sequence of the target is determined by imaging the fluorescence from the spots. The uncertainty of background in signal detection and statistical error in data analysis, primarily due to the error in the DNA amplification process and statistical distribution of the tags in the target DNA, have become the fundamental barriers in bringing the technology into application for clinical diagnostics. Furthermore, the dye and tagging process are expensive, making the cost of DNA chips inhibitive for clinical testing. These limitations and challenges make it difficult to implement DNA chip methods as a diagnostic tool in a pathology laboratory. The objective of this dissertation research is to provide an alternative approach that will address the above challenges. In this research, a label-free assay is designed and studied. Polystyrene (PS), a commonly used polymeric material, serves as the fluorescence agent. Probe ssDNA is covalently immobilized on polystyrene thin film that is supported by a reflecting substrate. When this chip is exposed to excitation light, fluorescence light intensity from PS is detected as the signal. Since the optical constants and conformations of ssDNA and dsDNA (double stranded DNA) are different, the measured fluorescence from PS changes for the same

  4. Non-stationary reconstruction for dynamic fluorescence molecular tomography with extended kalman filter.

    Science.gov (United States)

    Liu, Xin; Wang, Hongkai; Yan, Zhuangzhi

    2016-11-01

    Dynamic fluorescence molecular tomography (FMT) plays an important role in drug delivery research. However, the majority of current reconstruction methods focus on solving the stationary FMT problems. If the stationary reconstruction methods are applied to the time-varying fluorescence measurements, the reconstructed results may suffer from a high level of artifacts. In addition, based on the stationary methods, only one tomographic image can be obtained after scanning one circle projection data. As a result, the movement of fluorophore in imaged object may not be detected due to the relative long data acquisition time (typically >1 min). In this paper, we apply extended kalman filter (EKF) technique to solve the non-stationary fluorescence tomography problem. Especially, to improve the EKF reconstruction performance, the generalized inverse of kalman gain is calculated by a second-order iterative method. The numerical simulation, phantom, and in vivo experiments are performed to evaluate the performance of the method. The experimental results indicate that by using the proposed EKF-based second-order iterative (EKF-SOI) method, we cannot only clearly resolve the time-varying distributions of fluorophore within imaged object, but also greatly improve the reconstruction time resolution (~2.5 sec/frame) which makes it possible to detect the movement of fluorophore during the imaging processes.

  5. Surface plasmon-enhanced molecular fluorescence induced by gold nanostructures

    International Nuclear Information System (INIS)

    Teng, Y.; Ueno, K.; Shi, X.; Aoyo, D.; Misawa, H.; Qiu, J.

    2012-01-01

    The authors report on surface plasmon-enhanced fluorescence of Eosin Y molecules induced by gold nanostructures. Al 2 O 3 films deposited by atomic layer deposition with sub-nanometer resolution were used as the spacer layer to control the distance between molecules and the gold surface. As the thickness of the Al 2 O 3 film increased, the fluorescence intensity first increased and then decreased. The highest enhancement factor is achieved with a 1 nm Al 2 O 3 film. However, the trend for the fluorescence lifetime is the opposite. It first decreased and then increased. The changes in the fluorescence quantum yield were also calculated. The yield shows a similar trend to the fluorescence intensity. The competition between the surface plasmon-induced increase in the radiative decay rate and the gold-induced fluorescence quenching is responsible for the observed phenomenon. In addition, this competition strongly depends on the thickness of the spacer layer between Eosin Y molecules and the gold surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. The combination design for open and endoscopic surgery using fluorescence molecular imaging technology

    Science.gov (United States)

    Mao, Yamin; Jiang, Shixin; Ye, Jinzuo; An, Yu; Yang, Xin; Chi, Chongwei; Tian, Jie

    2015-03-01

    For clinical surgery, it is still a challenge to objectively determine tumor margins during surgery. With the development of medical imaging technology, fluorescence molecular imaging (FMI) method can provide real-time intraoperative tumor margin information. Furthermore, surgical navigation system based on FMI technology plays an important role for the aid of surgeons' precise tumor margin decision. However, detection depth is the most limitation exists in the FMI technique and the method convenient for either macro superficial detection or micro deep tissue detection is needed. In this study, we combined advantages of both open surgery and endoscopic imaging systems with FMI technology. Indocyanine green (ICG) experiments were performed to confirm the feasibility of fluorescence detection in our system. Then, the ICG signal was photographed in the detection area with our system. When the system connected with endoscope lens, the minimum quantity of ICG detected by our system was 0.195 ug. For aspect of C mount lens, the sensitivity of ICG detection with our system was 0.195ug. Our experiments results proved that it was feasible to detect fluorescence images with this combination method. Our system shows great potential in the clinical applications of precise dissection of various tumors

  7. Analysis of fluorescence quenching of pyronin B and pyronin Y by molecular oxygen in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Celebi, Neslihan [Faculty of Arts and Sciences, Department of Chemistry, Atatuerk University, 25240 Erzurum (Turkey); Arik, Mustafa [Faculty of Arts and Sciences, Department of Chemistry, Atatuerk University, 25240 Erzurum (Turkey); Onganer, Yavuz [Faculty of Arts and Sciences, Department of Chemistry, Atatuerk University, 25240 Erzurum (Turkey)]. E-mail: yonganer@atauni.edu.tr

    2007-09-15

    The fluorescence quenching of pyronin B and pyronin Y molecules by molecular oxygen in aqueous solution was studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques. In order to understand the quenching mechanism, fluorescence decays, absorption and fluorescence spectra of the probes were recorded as a function of the oxygen concentration and temperature. The quenching was found to be appreciable and shows positive deviation in the Stern-Volmer representation obtained from the fluorescence intensity ratio. Fluorescence quenching constants (k {sub q}) were calculated from the {tau} {sub o}/{tau} vs. [Q] plots having linear correlation and compared with calculated diffusion-controlled rate constants (k {sub diff}) values. Experimental results were in good agreement with the simultaneous dynamic and static quenching model.

  8. Analysis of fluorescence quenching of pyronin B and pyronin Y by molecular oxygen in aqueous solution

    International Nuclear Information System (INIS)

    Celebi, Neslihan; Arik, Mustafa; Onganer, Yavuz

    2007-01-01

    The fluorescence quenching of pyronin B and pyronin Y molecules by molecular oxygen in aqueous solution was studied by using steady-state and time-resolved fluorescence and UV-Vis absorption spectroscopy techniques. In order to understand the quenching mechanism, fluorescence decays, absorption and fluorescence spectra of the probes were recorded as a function of the oxygen concentration and temperature. The quenching was found to be appreciable and shows positive deviation in the Stern-Volmer representation obtained from the fluorescence intensity ratio. Fluorescence quenching constants (k q ) were calculated from the τ o /τ vs. [Q] plots having linear correlation and compared with calculated diffusion-controlled rate constants (k diff ) values. Experimental results were in good agreement with the simultaneous dynamic and static quenching model

  9. A study of MRI-guided diffuse fluorescence molecular tomography for monitoring PDT effects in pancreas cancer

    Science.gov (United States)

    Samkoe, Kimberley S.; Davis, Scott C.; Srinivasan, Subhadra; O'Hara, Julia A.; Hasan, Tayyaba; Pogue, Brian W.

    2009-06-01

    Over the last several decades little progress has been made in the therapy and treatment monitoring of pancreas adenocarcinoma, a devastating and aggressive form of cancer that has a 5-year patient survival rate of 3%. Currently, investigations for the use of interstitial Verteporfin photodynamic therapy (PDT) are being undertaken in both orthotopic xenograft mouse models and in human clinical trials. In the mouse models, magnetic resonance (MR) imaging has been used as a measure of surrogate response to Verteporfin PDT; however, MR imaging alone lacks the molecular information required to assess the metabolic function and growth rates of the tumor immediately after treatment. We propose the implementation of MR-guided fluorescence tomography in conjunction with a fluorescently labeled (IR-Dye 800 CW, LI-COR) epidermal growth factor (EGF) as a molecular measure of surrogate response. To demonstrate the effectiveness of MR-guided diffuse fluorescence tomography for molecular imaging, we have used the AsPC-1 (+EGFR) human pancreatic adenocarcinoma in an orthotopic mouse model. EGF IRDye 800CW was injected 48 hours prior to imaging. MR image sequences were collected simultaneously with the fluorescence data using a MR-coupled diffuse optical tomography system. Image reconstruction was performed multiple times with varying abdominal organ segmentation in order to obtain a optimal tomographic image. It is shown that diffuse fluorescence tomography of the orthotopic pancreas model is feasible, with consideration of confounding fluorescence signals from the multiple organs and tissues surrounding the pancreas. MR-guided diffuse fluorescence tomography will be used to monitor EGF response after photodynamic therapy. Additionally, it provide the opportunity to individualize subsequent therapies based on response to PDT as well as to evaluate the success of combination therapies, such as PDT with chemotherapy, antibody therapy or even radiation.

  10. Cyanine-based probe\\tag-peptide pair for fluorescence protein imaging and fluorescence protein imaging methods

    Science.gov (United States)

    Mayer-Cumblidge, M Uljana [Richland, WA; Cao, Haishi [Richland, WA

    2010-08-17

    A molecular probe comprises two arsenic atoms and at least one cyanine based moiety. A method of producing a molecular probe includes providing a molecule having a first formula, treating the molecule with HgOAc, and subsequently transmetallizing with AsCl.sub.3. The As is liganded to ethanedithiol to produce a probe having a second formula. A method of labeling a peptide includes providing a peptide comprising a tag sequence and contacting the peptide with a biarsenical molecular probe. A complex is formed comprising the tag sequence and the molecular probe. A method of studying a peptide includes providing a mixture containing a peptide comprising a peptide tag sequence, adding a biarsenical probe to the mixture, and monitoring the fluorescence of the mixture.

  11. Polypeptides Based Molecular Electronics

    National Research Council Canada - National Science Library

    Lam, Yeng M; Mhaisalkar, Subodh; Li, Lain-Jong; Dravid, Vinayak P; Shekhawat, Gajendra S; Suri, Raman

    2008-01-01

    ... the formation of molecular devices such as transistors, diodes, and sensors. We have designed the peptides, arranged them on substrates using self-assembly, Dip-PEN nanolithography, and also e-beam assisted lithography...

  12. Cleavable DNA-protein hybrid molecular beacon: A novel efficient signal translator for sensitive fluorescence anisotropy bioassay.

    Science.gov (United States)

    Hu, Pan; Yang, Bin

    2016-01-15

    Due to its unique features such as high sensitivity, homogeneous format, and independence on fluorescent intensity, fluorescence anisotropy (FA) assay has become a hotspot of study in oligonucleotide-based bioassays. However, until now most FA probes require carefully customized structure designs, and thus are neither generalizable for different sensing systems nor effective to obtain sufficient signal response. To address this issue, a cleavable DNA-protein hybrid molecular beacon was successfully engineered for signal amplified FA bioassay, via combining the unique stable structure of molecular beacon and the large molecular mass of streptavidin. Compared with single DNA strand probe or conventional molecular beacon, the DNA-protein hybrid molecular beacon exhibited a much higher FA value, which was potential to obtain high signal-background ratio in sensing process. As proof-of-principle, this novel DNA-protein hybrid molecular beacon was further applied for FA bioassay using DNAzyme-Pb(2+) as a model sensing system. This FA assay approach could selectively detect as low as 0.5nM Pb(2+) in buffer solution, and also be successful for real samples analysis with good recovery values. Compatible with most of oligonucleotide probes' designs and enzyme-based signal amplification strategies, the molecular beacon can serve as a novel signal translator to expand the application prospect of FA technology in various bioassays. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Separate and simultaneous binding effects of aspirin and amlodipine to human serum albumin based on fluorescence spectroscopic and molecular modeling characterizations: A mechanistic insight for determining usage drugs doses

    International Nuclear Information System (INIS)

    Abdollahpour, Nooshin; Asoodeh, Ahmad; Saberi, Mohammad Reza; Chamani, JamshidKhan

    2011-01-01

    The binding of aspirin (ASA) and amlodipine (AML) to human serum albumin (HSA) in aqueous solution was investigated by multiple techniques such as fluorescence quenching, resonance light scattering (RLS), three-dimensional fluorescence spectroscopy, FT-IR and zeta-potential measurements in an aqueous solution at pH=7.4. For the protein-ligand association reaction, fluorescence measurements can give important clues as to the binding of ligands to proteins, e.g., the binding mechanism, binding mode, binding constants, binding sites, etc. Fluorescence spectroscopy showed that ASA and AML could quench the HSA fluorescence spectra, and this quenching effect became more significant when both ASA and AML coexisted. The results pointed at the interaction between HSA and both drugs as ternary systems decreasing the binding constant and binding stability of the HSA-drug complex as a binary system. Therefore, by reducing the amount of drugs transported to their targets, the free drug concentration of the target would be reduced, lowering the efficacy of the drugs. It was demonstrated that there exists antagonistic behavior between the two drugs when it comes to binding of HSA. Furthermore, the fluorescence results also showed that the quenching mechanism of HSA-drug complexes as binary and ternary systems is a static procedure. The number of binding sites of HSA-ASA, (HSA-AML)ASA, HSA-AML and (HSA-ASA) AML were 1.31, 0.92, 1 and 0.93, respectively. Due to the existence of the antagonistic action between ASA and AML, the binding distance r was reduced. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that the antagonistic action between ASA and AML would alter the micro-environment around Trp and Tyr residues. Moreover, the simultaneous presence of ASA and AML during binding to HSA should be taken into account in multidrug therapy, as it induces the necessity of a monitoring therapy owing to the possible increase of uncontrolled toxic

  14. Separate and simultaneous binding effects of aspirin and amlodipine to human serum albumin based on fluorescence spectroscopic and molecular modeling characterizations: A mechanistic insight for determining usage drugs doses

    Energy Technology Data Exchange (ETDEWEB)

    Abdollahpour, Nooshin [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Asoodeh, Ahmad [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Saberi, Mohammad Reza [Department of Medical Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Chamani, JamshidKhan, E-mail: chamani@ibb.ut.ac.ir [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2011-09-15

    The binding of aspirin (ASA) and amlodipine (AML) to human serum albumin (HSA) in aqueous solution was investigated by multiple techniques such as fluorescence quenching, resonance light scattering (RLS), three-dimensional fluorescence spectroscopy, FT-IR and zeta-potential measurements in an aqueous solution at pH=7.4. For the protein-ligand association reaction, fluorescence measurements can give important clues as to the binding of ligands to proteins, e.g., the binding mechanism, binding mode, binding constants, binding sites, etc. Fluorescence spectroscopy showed that ASA and AML could quench the HSA fluorescence spectra, and this quenching effect became more significant when both ASA and AML coexisted. The results pointed at the interaction between HSA and both drugs as ternary systems decreasing the binding constant and binding stability of the HSA-drug complex as a binary system. Therefore, by reducing the amount of drugs transported to their targets, the free drug concentration of the target would be reduced, lowering the efficacy of the drugs. It was demonstrated that there exists antagonistic behavior between the two drugs when it comes to binding of HSA. Furthermore, the fluorescence results also showed that the quenching mechanism of HSA-drug complexes as binary and ternary systems is a static procedure. The number of binding sites of HSA-ASA, (HSA-AML)ASA, HSA-AML and (HSA-ASA) AML were 1.31, 0.92, 1 and 0.93, respectively. Due to the existence of the antagonistic action between ASA and AML, the binding distance r was reduced. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that the antagonistic action between ASA and AML would alter the micro-environment around Trp and Tyr residues. Moreover, the simultaneous presence of ASA and AML during binding to HSA should be taken into account in multidrug therapy, as it induces the necessity of a monitoring therapy owing to the possible increase of uncontrolled toxic

  15. Molecular quantification of genes encoding for green-fluorescent proteins

    DEFF Research Database (Denmark)

    Felske, A; Vandieken, V; Pauling, B V

    2003-01-01

    A quantitative PCR approach is presented to analyze the amount of recombinant green fluorescent protein (gfp) genes in environmental DNA samples. The quantification assay is a combination of specific PCR amplification and temperature gradient gel electrophoresis (TGGE). Gene quantification...... PCR strategy is a highly specific and sensitive way to monitor recombinant DNA in environments like the efflux of a biotechnological plant....

  16. Graphene oxide-sensitized molecularly imprinted opto-polymers for charge-transfer fluorescent sensing of cyanoguanidine.

    Science.gov (United States)

    Liu, Huilin; Zhou, Kaiwen; Chen, Xiaomo; Wang, Jing; Wang, Shuo; Sun, Baoguo

    2017-11-15

    The hierarchical structuring of materials offers exciting opportunities to construct functional sensors. Multiple processes were combined to create complex materials for the selective detection of cyanoguanidine (CYA) using graphene oxide-sensitized molecularly imprinted opto-polymers (MIOP). Molecular imprinting was used to construct molecular-scale analyte-selective cavities, graphene oxide was introduced to provide a platform for the polymerization, and increase the stability and binding kinetic properties, and 3-methacryloxy propyl trimethoxy silane-modified quantum dots were combined with a functional monomer to increase the fluorescence quantum yield. Polymer cross-linking and fluorescence intensity were optimized for molecular recognition and opto-sensing detection. Selective and sensitive, fluorescence sensing of CYA was possible at concentrations as low as to 1.6μM. It could be applied to the rapid and cost-effective monitoring of CYA in infant formula. The approach is generic and applicable to many molecules and conventional opto-sensors, based on molecularly imprinted polymer formulations, individually or in multiplexed arrays. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. A penalized linear and nonlinear combined conjugate gradient method for the reconstruction of fluorescence molecular tomography.

    Science.gov (United States)

    Shang, Shang; Bai, Jing; Song, Xiaolei; Wang, Hongkai; Lau, Jaclyn

    2007-01-01

    Conjugate gradient method is verified to be efficient for nonlinear optimization problems of large-dimension data. In this paper, a penalized linear and nonlinear combined conjugate gradient method for the reconstruction of fluorescence molecular tomography (FMT) is presented. The algorithm combines the linear conjugate gradient method and the nonlinear conjugate gradient method together based on a restart strategy, in order to take advantage of the two kinds of conjugate gradient methods and compensate for the disadvantages. A quadratic penalty method is adopted to gain a nonnegative constraint and reduce the illposedness of the problem. Simulation studies show that the presented algorithm is accurate, stable, and fast. It has a better performance than the conventional conjugate gradient-based reconstruction algorithms. It offers an effective approach to reconstruct fluorochrome information for FMT.

  18. Example-Based Super-Resolution Fluorescence Microscopy.

    Science.gov (United States)

    Jia, Shu; Han, Boran; Kutz, J Nathan

    2018-04-23

    Capturing biological dynamics with high spatiotemporal resolution demands the advancement in imaging technologies. Super-resolution fluorescence microscopy offers spatial resolution surpassing the diffraction limit to resolve near-molecular-level details. While various strategies have been reported to improve the temporal resolution of super-resolution imaging, all super-resolution techniques are still fundamentally limited by the trade-off associated with the longer image acquisition time that is needed to achieve higher spatial information. Here, we demonstrated an example-based, computational method that aims to obtain super-resolution images using conventional imaging without increasing the imaging time. With a low-resolution image input, the method provides an estimate of its super-resolution image based on an example database that contains super- and low-resolution image pairs of biological structures of interest. The computational imaging of cellular microtubules agrees approximately with the experimental super-resolution STORM results. This new approach may offer potential improvements in temporal resolution for experimental super-resolution fluorescence microscopy and provide a new path for large-data aided biomedical imaging.

  19. Interaction of Chelerythrine with Keyhole Limpet Hemocyanin: a Fluorescence Spectroscopy and Molecular Docking Study

    Science.gov (United States)

    Zhong, M.; Long, R. Q.; Wang, Y. H.; Chen, C. L.

    2018-05-01

    The quenching mechanism between chelerythrine (CHE) and keyhole limpet hemocyanin (KLH) was investigated using fluorescence spectroscopy and molecular docking. The experiments were conducted at three different temperatures (293, 298, and 303 K). The results revealed that the intrinsic fluorescence of KLH was strongly quenched by CHE through a static quenching mechanism. The thermodynamic parameters (ΔG, ΔH, and ΔS) of the interaction were calculated, indicating that the interaction between CHE and KLH was spontaneous and that van der Waals forces and hydrogen bond formation played major roles in the binding process. The intrinsic fluorescence of the tyrosine and tryptophan residues in KLH was studied by synchronous fluorescence, which suggested that CHE changed the conformation of KLH. Finally, molecular docking was used to obtain detailed information on the binding sites and binding affinities between CHE and KLH.

  20. Fluorescent chemosensor based on urea/thiourea moiety for sensing of Hg(II) ions in an aqueous medium with high sensitivity and selectivity: A comparative account on effect of molecular architecture on chemosensing

    Science.gov (United States)

    Mishra, Jayanti; Kaur, Harpreet; Ganguli, Ashok K.; Kaur, Navneet

    2018-06-01

    Mercury is a well-known heavy metal ion which is extremely poisonous to health but is still employed in the form of mercury salts and organomercury compounds in various industrial, anthropological and agricultural activities. Henceforth, its sensing in aqueous medium is an area of great interest in order to avoid its hazardous effect. In the present manuscript, urea/thiourea linkage bearing four organic ligands (1a, 1b, 2a and 2b) are synthesized by a three-step synthetic approach. The organic ligands were then employed to develop organic nanoparticles by re-precipitation method which was further probed for their selective recognition behavior in an aqueous medium using fluorescence spectroscopy. The fluorescence emission profile of the ONPs is used as a tool for the tracking of sensing behavior. The ONPs of 1b has shown selective recognition towards Hg(II) in aqueous medium evidenced by enhancement of fluorescence emission intensity after complexation of 1b ONP with Hg(II), among several alkali, alkaline earth and transition metal ions with a detection limit of the order of 0.84 μM. The ability of the proposed sensor to sense Hg(II) ions with high selectivity and sensitivity could be accounted to photo-induced electron transfer (PET) "OFF" mechanism at λem = 390 nm. This study reveals the application of the proposed thiourea-based sensor for the selective recognition of the Hg(II) ions in an aqueous medium.

  1. CMOS Time-Resolved, Contact, and Multispectral Fluorescence Imaging for DNA Molecular Diagnostics

    Directory of Open Access Journals (Sweden)

    Nan Guo

    2014-10-01

    Full Text Available Instrumental limitations such as bulkiness and high cost prevent the fluorescence technique from becoming ubiquitous for point-of-care deoxyribonucleic acid (DNA detection and other in-field molecular diagnostics applications. The complimentary metal-oxide-semiconductor (CMOS technology, as benefited from process scaling, provides several advanced capabilities such as high integration density, high-resolution signal processing, and low power consumption, enabling sensitive, integrated, and low-cost fluorescence analytical platforms. In this paper, CMOS time-resolved, contact, and multispectral imaging are reviewed. Recently reported CMOS fluorescence analysis microsystem prototypes are surveyed to highlight the present state of the art.

  2. Comparison of Cherenkov excited fluorescence and phosphorescence molecular sensing from tissue with external beam irradiation.

    Science.gov (United States)

    Lin, Huiyun; Zhang, Rongxiao; Gunn, Jason R; Esipova, Tatiana V; Vinogradov, Sergei; Gladstone, David J; Jarvis, Lesley A; Pogue, Brian W

    2016-05-21

    Ionizing radiation delivered by a medical linear accelerator (LINAC) generates Cherenkov emission within the treated tissue. A fraction of this light, in the 600-900 nm wavelength region, propagates through centimeters of tissue and can be used to excite optical probes in vivo, enabling molecular sensing of tissue analytes. The success of isolating the emission signal from this Cherenkov excitation background is dependent on key factors such as: (i) the Stokes shift of the probe spectra; (ii) the excited state lifetime; (iii) the probe concentration; (iv) the depth below the tissue surface; and (v) the radiation dose used. Previous studies have exclusively focused on imaging phosphorescent dyes, rather than fluorescent dyes. However there are only a few biologically important phosphorescent dyes and yet in comparison there are thousands of biologically relevant fluorescent dyes. So in this study the focus was a study of efficacy of Cherenkov-excited luminescence using fluorescent commercial near-infrared probes, IRDye 680RD, IRDye 700DX, and IRDye 800CW, and comparing them to the well characterized phosphorescent probe Oxyphor PtG4, an oxygen sensitive dye. Each probe was excited by Cherenkov light from a 6 MV external radiation beam, and measured in continuous wave or time-gated modes. The detection was performed by spectrally resolving the luminescence signals, and measuring them with spectrometer-based separation on an ICCD detector. The results demonstrate that IRDye 700DX and PtG4 allowed for the maximal signal to noise ratio. In the case of the phosphorescent probe, PtG4, with emission decays on the microsecond (μs) time scale, time-gated acquisition was possible, and it allowed for higher efficacy in terms of the probe concentration and detection depth. Phantoms containing the probe at 5 mm depth could be detected at concentrations down to the nanoMolar range, and at depths into the tissue simulating phantom near 3 cm. In vivo studies showed that 5

  3. Full-direct method for imaging pharmacokinetic parameters in dynamic fluorescence molecular tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guanglei, E-mail: guangleizhang@bjtu.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); Department of Biomedical Engineering, School of Computer and Information Technology, Beijing Jiaotong University, Beijing 100044 (China); Pu, Huangsheng; Liu, Fei; Bai, Jing [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); He, Wei [China Institute of Sport Science, Beijing 100061 (China); Luo, Jianwen, E-mail: luo-jianwen@tsinghua.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084 (China); Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing 100084 (China)

    2015-02-23

    Images of pharmacokinetic parameters (also known as parametric images) in dynamic fluorescence molecular tomography (FMT) can provide three-dimensional metabolic information for biological studies and drug development. However, the ill-posed nature of FMT and the high temporal variation of fluorophore concentration together make it difficult to obtain accurate parametric images in small animals in vivo. In this letter, we present a method to directly reconstruct the parametric images from the boundary measurements based on hybrid FMT/X-ray computed tomography (XCT) system. This method can not only utilize structural priors obtained from the XCT system to mitigate the ill-posedness of FMT but also make full use of the temporal correlations of boundary measurements to model the high temporal variation of fluorophore concentration. The results of numerical simulation and mouse experiment demonstrate that the proposed method leads to significant improvements in the reconstruction quality of parametric images.

  4. Molecular engineering and fluorescence for the detection of toxic cations; Ingenierie moleculaire et fluorescence pour la reconnaissance de cations toxiques

    Energy Technology Data Exchange (ETDEWEB)

    Souchon, V

    2007-11-15

    This work is a part of the 'Toxicologie Nucleaire Environnementale' program which aims at studying the effects on the living of heavy metals or radionuclides involved in nuclear industry. Most particularly, it deals with the design of new fluorescent sensors for the selective detection of Pb{sup 2+}, Cd{sup 2+} and Cs{sup +} in biological media. Several fluorescent calixarenes possessing nitrogen atoms were synthesized and their properties as potential lead sensors were investigated. One of them could be used in experimental conditions close to biological media and new target compounds with amide functional groups were proposed. Many approaches were considered for the design of selective fluorescent sensors for cadmium. On the basis of literature results, many chelating compounds incorporating sulfur atoms were synthesized but showed no significant affinity towards cadmium. On the opposite, compounds functionalized with several pyridine-2'-yl-1,2,3-triazol fluorescent moieties linked to a {beta}-cyclodextrin or a calix[4]arene showed good affinity for cadmium in methanol, but the selectivity was found to be insufficient. In contrast, very satisfying results in terms of both selectivity and sensitivity could be obtained with the commercial calcium sensor Rhod-5N in an aqueous medium at neutral pH. Lastly, micromolar detection limits for the selective detection of caesium were reached in an aqueous medium at neutral pH thanks to a new sulfonated fluorescent calixarene with two appended crown-ethers. An original complexation mechanism was proposed and validated by molecular modelling (DFT). (author)

  5. Detection of trace tetracycline in fish via synchronous fluorescence quenching with carbon quantum dots coated with molecularly imprinted silica

    Science.gov (United States)

    Yang, Ji; Lin, Zheng-Zhong; Nur, A.-Zha; Lu, Yan; Wu, Ming-Hui; Zeng, Jun; Chen, Xiao-Mei; Huang, Zhi-Yong

    2018-02-01

    A novel fluorescence-based sensor combining synchronous fluorescence spectroscopy (SFS) with molecularly imprinted polymers (MIPs) was fabricated with reverse microemulsion method. Tetracycline (TC), (3-aminopropyl) triethoxysilane (APTES), tetraethyl orthosilicate (TEOS) and carbon quantum dots (CDs) were used as template, functional monomer, cross-linker and signal sources respectively in the probe preparation. A synchronous fluorescence emission (λem) at 355 nm was observed for the prepared MIP-coated CDs (MIP@CDs) particles when the wavelength interval (Δλ) was set as 70 nm, and the synchronous fluorescence intensity could be rapidly and efficiently quenched by TC based on inner filter effect (IFE). The quenching efficiencies of synchronous fluorescence intensity was linearly fitted with tetracycline (TC) concentrations ranging from 0.1 to 50 μmol L- 1 with a detection limit (DL) of 9 nmol L- 1 (3σ, n = 9). The MIP@CDs was used as a probe to detect TC in fish samples with the recoveries ranging from 98.4% to 103.1% and the relative standard deviation less than 6.0%. The results illustrated that the as-prepared MIP@CDs could be applied to the detection of trace TC in fish samples with rapidity, high sensitivity and accuracy.

  6. Suppression of Kasha's rule as a mechanism for fluorescent molecular rotors and aggregation-induced emission

    Science.gov (United States)

    Qian, Hai; Cousins, Morgan E.; Horak, Erik H.; Wakefield, Audrey; Liptak, Matthew D.; Aprahamian, Ivan

    2017-01-01

    Although there are some proposed explanations for aggregation-induced emission, a phenomenon with applications that range from biosensors to organic light-emitting diodes, current understanding of the quantum-mechanical origin of this photophysical behaviour is limited. To address this issue, we assessed the emission properties of a series of BF2-hydrazone-based dyes as a function of solvent viscosity. These molecules turned out to be highly efficient fluorescent molecular rotors. This property, in addition to them being aggregation-induced emission luminogens, enabled us to probe deeper into their emission mechanism. Time-dependent density functional theory calculations and experimental results showed that the emission is not from the S1 state, as predicted from Kasha's rule, but from a higher energy (>S1) state. Furthermore, we found that suppression of internal conversion to the dark S1 state by restricting the rotor rotation enhances fluorescence, which leads to the proposal that suppression of Kasha's rule is the photophysical mechanism responsible for emission in both viscous solution and the solid state.

  7. Enhanced spatial resolution in fluorescence molecular tomography using restarted L1-regularized nonlinear conjugate gradient algorithm.

    Science.gov (United States)

    Shi, Junwei; Liu, Fei; Zhang, Guanglei; Luo, Jianwen; Bai, Jing

    2014-04-01

    Owing to the high degree of scattering of light through tissues, the ill-posedness of fluorescence molecular tomography (FMT) inverse problem causes relatively low spatial resolution in the reconstruction results. Unlike L2 regularization, L1 regularization can preserve the details and reduce the noise effectively. Reconstruction is obtained through a restarted L1 regularization-based nonlinear conjugate gradient (re-L1-NCG) algorithm, which has been proven to be able to increase the computational speed with low memory consumption. The algorithm consists of inner and outer iterations. In the inner iteration, L1-NCG is used to obtain the L1-regularized results. In the outer iteration, the restarted strategy is used to increase the convergence speed of L1-NCG. To demonstrate the performance of re-L1-NCG in terms of spatial resolution, simulation and physical phantom studies with fluorescent targets located with different edge-to-edge distances were carried out. The reconstruction results show that the re-L1-NCG algorithm has the ability to resolve targets with an edge-to-edge distance of 0.1 cm at a depth of 1.5 cm, which is a significant improvement for FMT.

  8. Radiative transport-based frequency-domain fluorescence tomography

    International Nuclear Information System (INIS)

    Joshi, Amit; Rasmussen, John C; Sevick-Muraca, Eva M; Wareing, Todd A; McGhee, John

    2008-01-01

    We report the development of radiative transport model-based fluorescence optical tomography from frequency-domain boundary measurements. The coupled radiative transport model for describing NIR fluorescence propagation in tissue is solved by a novel software based on the established Attila(TM) particle transport simulation platform. The proposed scheme enables the prediction of fluorescence measurements with non-contact sources and detectors at a minimal computational cost. An adjoint transport solution-based fluorescence tomography algorithm is implemented on dual grids to efficiently assemble the measurement sensitivity Jacobian matrix. Finally, we demonstrate fluorescence tomography on a realistic computational mouse model to locate nM to μM fluorophore concentration distributions in simulated mouse organs

  9. A Quantitative Fluorescence-Based Lipase Assay

    Directory of Open Access Journals (Sweden)

    Giovanna Lomolino

    2012-01-01

    Full Text Available An easy and fast gel diffusion assay for detecting and monitoring lipase activity by quantification of fluorescein is described. By measuring the intensity of fluorescein, it is possible to obtain a calibration curve with a regression coefficient better than by using the radius of fluorescent haloes. Through the quantification of fluorescence intensity of fluorescein released after the hydrolysis of a fluorescent ester, fluorescein dibutyrate, used as substrate in agar plates, commercial and skimmed milk lipase activity were studied. Moreover, with this method, lipase activity can be monitored in reaction medium that contains compounds which are affected by turbidity or cause measurement interference for UV-spectrophotometer and fluorimeter. In this experiment, boiled skimmed milk was dispersed in the agar gel with fluorescein dibutyrate, and it was used as a reaction medium to mimic natural conditions. The development of such an assay has a potential for applications in industries ranging from pharmaceuticals to food production and monitoring.

  10. Ultrasound guided fluorescence molecular tomography with improved quantification by an attenuation compensated born-normalization and in vivo preclinical study of cancer

    International Nuclear Information System (INIS)

    Li, Baoqiang; Berti, Romain; Abran, Maxime; Lesage, Frédéric

    2014-01-01

    Ultrasound imaging, having the advantages of low-cost and non-invasiveness over MRI and X-ray CT, was reported by several studies as an adequate complement to fluorescence molecular tomography with the perspective of improving localization and quantification of fluorescent molecular targets in vivo. Based on the previous work, an improved dual-modality Fluorescence-Ultrasound imaging system was developed and then validated in imaging study with preclinical tumor model. Ultrasound imaging and a profilometer were used to obtain the anatomical prior information and 3D surface, separately, to precisely extract the tissue boundary on both sides of sample in order to achieve improved fluorescence reconstruction. Furthermore, a pattern-based fluorescence reconstruction on the detection side was incorporated to enable dimensional reduction of the dataset while keeping the useful information for reconstruction. Due to its putative role in the current imaging geometry and the chosen reconstruction technique, we developed an attenuation compensated Born-normalization method to reduce the attenuation effects and cancel off experimental factors when collecting quantitative fluorescence datasets over large area. Results of both simulation and phantom study demonstrated that fluorescent targets could be recovered accurately and quantitatively using this reconstruction mechanism. Finally, in vivo experiment confirms that the imaging system associated with the proposed image reconstruction approach was able to extract both functional and anatomical information, thereby improving quantification and localization of molecular targets

  11. Enhanced fluorescence of a molecular dipole near metal nanoparticle

    International Nuclear Information System (INIS)

    Pustovit, Vitaliy N.

    2010-01-01

    We study theoretically radiative and nonradiative decay of a single molecule near small gold nanoparticle. The local field enhancement leads to an increased radiative decay rate while the energy transfer from molecule to optically inactive electronic states in nanoparticle results in a decrease in the fluorescence quantum efficiency for small molecule-nanoparticle distances. We performed a DFT-TDLDA calculation of both the enhancement and the quenching for small nanometersized gold nanoparticles. We found that in close proximity to the surface, the nonradiative decay rate is dominated by generation of electron-hole pairs out of the Fermi sea resulting in a significantly lower quantum efficiency as compared to that obtained from electromagnetic calculations. For large distances, the efficiency is maximal for molecule polarized normal to the surface, whereas for small distances it is maximal for parallel orientation.

  12. Enhanced fluorescence of a molecular dipole near metal nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Pustovit, Vitaliy N., E-mail: pustovit@ccmsi.u [Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, General Naumov Street 17, 03164 Kyiv-164 (Ukraine)

    2010-01-15

    We study theoretically radiative and nonradiative decay of a single molecule near small gold nanoparticle. The local field enhancement leads to an increased radiative decay rate while the energy transfer from molecule to optically inactive electronic states in nanoparticle results in a decrease in the fluorescence quantum efficiency for small molecule-nanoparticle distances. We performed a DFT-TDLDA calculation of both the enhancement and the quenching for small nanometersized gold nanoparticles. We found that in close proximity to the surface, the nonradiative decay rate is dominated by generation of electron-hole pairs out of the Fermi sea resulting in a significantly lower quantum efficiency as compared to that obtained from electromagnetic calculations. For large distances, the efficiency is maximal for molecule polarized normal to the surface, whereas for small distances it is maximal for parallel orientation.

  13. Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

    Energy Technology Data Exchange (ETDEWEB)

    Stringer, R. Cody, E-mail: rcsm84@mail.mizzou.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States); Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu [Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO (United States); Grant, Sheila A., E-mail: grantsa@missouri.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States)

    2011-10-10

    Highlights: {yields} Imprinted polymers prepared using precipitation polymerization. {yields} Comparison of chloroform and water as polymerization solvent. {yields} Imprinted polymer doped with quantum dots for fluorescent sensor. {yields} Fluorescent imprinted polymer used to detect nitroaromatic explosives. {yields} Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 {mu}M, as compared to 100 {mu}M for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the

  14. Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

    International Nuclear Information System (INIS)

    Stringer, R. Cody; Gangopadhyay, Shubhra; Grant, Sheila A.

    2011-01-01

    Highlights: → Imprinted polymers prepared using precipitation polymerization. → Comparison of chloroform and water as polymerization solvent. → Imprinted polymer doped with quantum dots for fluorescent sensor. → Fluorescent imprinted polymer used to detect nitroaromatic explosives. → Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 μM, as compared to 100 μM for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the enhanced chemical properties of

  15. Tomato seeds maturity detection system based on chlorophyll fluorescence

    Science.gov (United States)

    Li, Cuiling; Wang, Xiu; Meng, Zhijun

    2016-10-01

    Chlorophyll fluorescence intensity can be used as seed maturity and quality evaluation indicator. Chlorophyll fluorescence intensity of seed coats is tested to judge the level of chlorophyll content in seeds, and further to judge the maturity and quality of seeds. This research developed a detection system of tomato seeds maturity based on chlorophyll fluorescence spectrum technology, the system included an excitation light source unit, a fluorescent signal acquisition unit and a data processing unit. The excitation light source unit consisted of two high power LEDs, two radiators and two constant current power supplies, and it was designed to excite chlorophyll fluorescence of tomato seeds. The fluorescent signal acquisition unit was made up of a fluorescence spectrometer, an optical fiber, an optical fiber scaffolds and a narrowband filter. The data processing unit mainly included a computer. Tomato fruits of green ripe stage, discoloration stage, firm ripe stage and full ripe stage were harvested, and their seeds were collected directly. In this research, the developed tomato seeds maturity testing system was used to collect fluorescence spectrums of tomato seeds of different maturities. Principal component analysis (PCA) method was utilized to reduce the dimension of spectral data and extract principal components, and PCA was combined with linear discriminant analysis (LDA) to establish discriminant model of tomato seeds maturity, the discriminant accuracy was greater than 90%. Research results show that using chlorophyll fluorescence spectrum technology is feasible for seeds maturity detection, and the developed tomato seeds maturity testing system has high detection accuracy.

  16. Confirmation of molecular formulas of metallic complexes through X-ray fluorescence quantitative analysis

    International Nuclear Information System (INIS)

    Filgueiras, C.A.L.; Marques, E.V.; Machado, R.M.

    1984-01-01

    X-ray fluorescence spectrophotometry was employed to determined the metal content in a series of five transition element complexes (Mn, Ti, Zn, V). The results confirmed the molecular formulas of these complexes, already proposed on the basis of elemental microanalysis, solution condutimetry and other analytical methods. (C.L.B.) [pt

  17. Optimized measurements of separations and angles between intra-molecular fluorescent markers

    DEFF Research Database (Denmark)

    Mortensen, Kim; Sung, Jongmin; Flyvbjerg, Henrik

    2015-01-01

    We demonstrate a novel, yet simple tool for the study of structure and function of biomolecules by extending two-colour co-localization microscopy to fluorescent molecules with fixed orientations and in intra-molecular proximity. From each colour-separated microscope image in a time-lapse movie...

  18. Exploring Fluorescence Antibunching in Solution To Determine the Stoichiometry of Molecular Complexes

    Czech Academy of Sciences Publication Activity Database

    Sýkora, Jan; Kaiser, K.; Gregor, I.; Bönigk, W.; Schmalzing, G.; Enderlain, J.

    2007-01-01

    Roč. 79, - (2007), s. 4040-4049 ISSN 0003-2700 R&D Projects: GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z40400503 Keywords : exploring fluorescence antibunching * molecular complex es * biophysical methods Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.287, year: 2007

  19. Dual-Modal Colorimetric/Fluorescence Molecular Probe for Ratiometric Sensing of pH and Its Application.

    Science.gov (United States)

    Wu, Luling; Li, Xiaolin; Huang, Chusen; Jia, Nengqin

    2016-08-16

    As traditional pH meters cannot work well for minute regions (such as subcellular organelles) and in harsh media, molecular pH-sensitive devices for monitoring pH changes in diverse local heterogeneous environments are urgently needed. Here, we report a new dual-modal colorimetric/fluorescence merocyanine-based molecular probe (CPH) for ratiometric sensing of pH. Compared with previously reported pH probes, CPH bearing the benzyl group at the nitrogen position of the indolium group and the phenol, which is used as the acceptor for proton, could respond to pH changes immediately through both the ratiometric fluorescence signal readout and naked-eye colorimetric observation. The sensing process was highly stable and reversible. Most importantly, the suitable pKa value (6.44) allows CPH to presumably accumulate in lysosomes and become a lysosome-target fluorescent probe. By using CPH, the intralysosomal pH fluctuation stimulated by antimalaria drug chloroquine was successfully tracked in live cells through the ratiometric fluorescence images. Additionally, CPH could be immobilized on test papers, which exhibited a rapid and reversible colorimetric response to acid/base vapor through the naked-eye colorimetric analysis. This proof-of-concept study presents the potential application of CPH as a molecular tool for monitoring intralysosomal pH fluctuation in live cells, as well as paves the way for developing the economic, reusable, and fast-response optical pH meters for colorimetric sensing acid/base vapor with direct naked-eye observation.

  20. Intravascular near-infrared fluorescence molecular imaging of atherosclerosis: toward coronary arterial visualization of biologically high-risk plaques

    Science.gov (United States)

    Calfon, Marcella A.; Vinegoni, Claudio; Ntziachristos, Vasilis; Jaffer, Farouc A.

    2010-01-01

    New imaging methods are urgently needed to identify high-risk atherosclerotic lesions prior to the onset of myocardial infarction, stroke, and ischemic limbs. Molecular imaging offers a new approach to visualize key biological features that characterize high-risk plaques associated with cardiovascular events. While substantial progress has been realized in clinical molecular imaging of plaques in larger arterial vessels (carotid, aorta, iliac), there remains a compelling, unmet need to develop molecular imaging strategies targeted to high-risk plaques in human coronary arteries. We present recent developments in intravascular near-IR fluorescence catheter-based strategies for in vivo detection of plaque inflammation in coronary-sized arteries. In particular, the biological, light transmission, imaging agent, and engineering principles that underlie a new intravascular near-IR fluorescence sensing method are discussed. Intravascular near-IR fluorescence catheters appear highly translatable to the cardiac catheterization laboratory, and thus may offer a new in vivo method to detect high-risk coronary plaques and to assess novel atherosclerosis biologics.

  1. Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET with Fluorescent Materials

    Directory of Open Access Journals (Sweden)

    Hongyan Xia

    2017-12-01

    Full Text Available Studies on the following were reviewed: (1 the structure of spiropyrans and spirooxazines (two kinds of spiro compounds under external stimuli and (2 the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on, spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP, the ring-opened merocyanine (MC form, and the protonated ring-opened form (MCH. This is due to the breakage of the spiro C–O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1 the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2 composite systems based on spiropyrans and spirooxazines, and (3 fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements.

  2. Synthesis of dye/fluorescent functionalized dendrons based on cyclotriphosphazene

    Directory of Open Access Journals (Sweden)

    Aurélien Hameau

    2011-11-01

    Full Text Available Functionalized phenols based on tyramine were synthesized in order to be selectively grafted on to hexachlorocyclotriphosphazene, affording a variety of functionalized dendrons of type AB5. The B functions comprised fluorescent groups (dansyl or dyes (dabsyl, whereas the A function was provided by either an aldehyde or an amine. The characterization of these dendrons is reported. An unexpected behaviour of a fluorescent and water-soluble dendron based on dansyl groups in mixtures of dioxane/water was observed.

  3. Fluorescence imaging with near-infrared light: new technological advances that enable in vivo molecular imaging

    International Nuclear Information System (INIS)

    Ntziachristos, Vasilis; Bremer, Christoph; Weissleder, Ralph

    2003-01-01

    A recent development in biomedical imaging is the non-invasive mapping of molecular events in intact tissues using fluorescence. Underpinning to this development is the discovery of bio-compatible, specific fluorescent probes and proteins and the development of highly sensitive imaging technologies for in vivo fluorescent detection. Of particular interest are fluorochromes that emit in the near infrared (NIR), a spectral window, whereas hemoglobin and water absorb minimally so as to allow photons to penetrate for several centimetres in tissue. In this review article we concentrate on optical imaging technologies used for non-invasive imaging of the distribution of such probes. We illuminate the advantages and limitations of simple photographic methods and turn our attention to fluorescence-mediated molecular tomography (FMT), a technique that can three-dimensionally image gene expression by resolving fluorescence activation in deep tissues. We describe theoretical specifics, and we provide insight into its in vivo capacity and the sensitivity achieved. Finally, we discuss its clinical feasibility. (orig.)

  4. Synthesis, characterization and fluorescence performance of a waterborne polyurethane-based polymeric dye

    Energy Technology Data Exchange (ETDEWEB)

    Xianhai, Hu, E-mail: hxyh@aiai.edu.cn [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); School of Materials and Chemical Engineering, Building Energy Efficiency Research Institute, Anhui University of Architecture, Hefei 230022 (China); Zhang, Xingyuan, E-mail: zxym@ustc.edu.cn [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Liu, Jin [School of Materials and Chemical Engineering, Building Energy Efficiency Research Institute, Anhui University of Architecture, Hefei 230022 (China); Dai, Jiabing [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China)

    2013-10-15

    A novel anionic waterborne polyurethane-based fluorescent dye WPU-DV26 was synthesized by incorporating the molecular structure of disperse violet 26 (DV26) into the polyurethane chain. The structure of WPU-DV26 was confirmed by means of Fourier transform infrared spectroscopy and UV–vis absorption analysis. Comparing to the UV–vis spectrum of DV26, WPU-DV26 showed a hypsochromic shift from the absorption maxima of 518, 558, 609 nm to 510, 548, 586 nm, respectively. WPU-DV26 can form stable latex in water. The number average molecular weight and its distribution index, and average latex particle size for WPU-DV26 were determined to be 2.33×10{sup 4}, 1.36 and 80 nm, respectively. The improved thermal stability of WPU-DV26 can be attributed to the embedded anthraquinone unit of DV26. It was found that both the intensity and stability of the fluorescence of WPU-DV26 latex were improved significantly compared with those of DV26. -- Highlights: ► A waterborne polyurethane-based polymeric dye was synthesized. ► The fluorescence intensity of WPU-DV26 emulsion was enhanced greatly compared with that of DV26. ► The fluorescence stability of WPU-DV26 emulsion was fine not only for long term storage but also for fluorescence quencher.

  5. Theoretical analysis of fluorescence signals in filamentation of femtosecond laser pulses in nitrogen molecular gas

    International Nuclear Information System (INIS)

    Arevalo, E.; Becker, A.

    2005-01-01

    We study numerically and analytically the role of the combined effect of self-focusing, geometrical focusing, and the plasma defocusing in the formation of the fluorescence signal during the filamentation of a Ti:sapphire laser pulse in nitrogen molecular gas. Results of numerical simulations are used to estimate the number of excited ions in the focal volume, which is proportional to the fluorescence signal. We find good agreement between the theoretical results and the experimental data, showing that such data can be used to get further insight into the effective focal volume during filamentation of femtosecond laser pulses in transparent media

  6. Fluorescence quenching of Rhodamine B base by two amines

    Science.gov (United States)

    Bakkialakshmi, S.; Selvarani, P.; Chenthamarai, S.

    2013-03-01

    Fluorescence quenching of Rhodamine B base (RhB) in DMF solution has been studied at different concentrations of the amine Triethyl amine (TEA) and n-butyl amine (NBA) at room temperature. It has been observed that the fluorescence intensity of RhB decrease with increase in the concentration of the TEA and NBA. It has been observed that the quenching due to amines proceeds via dynamic quenching process. The rate constants for the quenching process have been calculated using Stern-Volmer equation. Time resolved fluorescence study and 1H NMR spectral study have also been carried out and discussed.

  7. Hue-shifted monomeric variants of Clavularia cyan fluorescent protein: identification of the molecular determinants of color and applications in fluorescence imaging

    Directory of Open Access Journals (Sweden)

    Davidson Michael W

    2008-03-01

    Full Text Available Abstract Background In the 15 years that have passed since the cloning of Aequorea victoria green fluorescent protein (avGFP, the expanding set of fluorescent protein (FP variants has become entrenched as an indispensable toolkit for cell biology research. One of the latest additions to the toolkit is monomeric teal FP (mTFP1, a bright and photostable FP derived from Clavularia cyan FP. To gain insight into the molecular basis for the blue-shifted fluorescence emission we undertook a mutagenesis-based study of residues in the immediate environment of the chromophore. We also employed site-directed and random mutagenesis in combination with library screening to create new hues of mTFP1-derived variants with wavelength-shifted excitation and emission spectra. Results Our results demonstrate that the protein-chromophore interactions responsible for blue-shifting the absorbance and emission maxima of mTFP1 operate independently of the chromophore structure. This conclusion is supported by the observation that the Tyr67Trp and Tyr67His mutants of mTFP1 retain a blue-shifted fluorescence emission relative to their avGFP counterparts (that is, Tyr66Trp and Tyr66His. Based on previous work with close homologs, His197 and His163 are likely to be the residues with the greatest contribution towards blue-shifting the fluorescence emission. Indeed we have identified the substitutions His163Met and Thr73Ala that abolish or disrupt the interactions of these residues with the chromophore. The mTFP1-Thr73Ala/His163Met double mutant has an emission peak that is 23 nm red-shifted from that of mTFP1 itself. Directed evolution of this double mutant resulted in the development of mWasabi, a new green fluorescing protein that offers certain advantages over enhanced avGFP (EGFP. To assess the usefulness of mTFP1 and mWasabi in live cell imaging applications, we constructed and imaged more than 20 different fusion proteins. Conclusion Based on the results of our

  8. Application of locked nucleic acid-based probes in fluorescence in situ hybridization

    DEFF Research Database (Denmark)

    Fontenete, Sílvia; Carvalho, Daniel R; Guimarães, Nuno

    2016-01-01

    of nucleic acid mimics used as mixmers in LNA-based probes strongly influence the efficiency of detection. LNA probes with 10 to 15 mers showed the highest efficiency. Additionally, the combination of 2′-OMe RNA with LNA allowed an increase on the fluorescence intensities of the probes. Overall......Fluorescence in situ hybridization (FISH) employing nucleic acid mimics as probes is becoming an emerging molecular tool in the microbiology area for the detection and visualization of microorganisms. However, the impact that locked nucleic acid (LNA) and 2′-O-methyl (2′-OMe) RNA modifications have...

  9. Molecular imaging needles: dual-modality optical coherence tomography and fluorescence imaging of labeled antibodies deep in tissue

    Science.gov (United States)

    Scolaro, Loretta; Lorenser, Dirk; Madore, Wendy-Julie; Kirk, Rodney W.; Kramer, Anne S.; Yeoh, George C.; Godbout, Nicolas; Sampson, David D.; Boudoux, Caroline; McLaughlin, Robert A.

    2015-01-01

    Molecular imaging using optical techniques provides insight into disease at the cellular level. In this paper, we report on a novel dual-modality probe capable of performing molecular imaging by combining simultaneous three-dimensional optical coherence tomography (OCT) and two-dimensional fluorescence imaging in a hypodermic needle. The probe, referred to as a molecular imaging (MI) needle, may be inserted tens of millimeters into tissue. The MI needle utilizes double-clad fiber to carry both imaging modalities, and is interfaced to a 1310-nm OCT system and a fluorescence imaging subsystem using an asymmetrical double-clad fiber coupler customized to achieve high fluorescence collection efficiency. We present, to the best of our knowledge, the first dual-modality OCT and fluorescence needle probe with sufficient sensitivity to image fluorescently labeled antibodies. Such probes enable high-resolution molecular imaging deep within tissue. PMID:26137379

  10. Self-prior strategy for organ reconstruction in fluorescence molecular tomography.

    Science.gov (United States)

    Zhou, Yuan; Chen, Maomao; Su, Han; Luo, Jianwen

    2017-10-01

    The purpose of this study is to propose a strategy for organ reconstruction in fluorescence molecular tomography (FMT) without prior information from other imaging modalities, and to overcome the high cost and ionizing radiation caused by the traditional structural prior strategy. The proposed strategy is designed as an iterative architecture to solve the inverse problem of FMT. In each iteration, a short time Fourier transform (STFT) based algorithm is used to extract the self-prior information in the space-frequency energy spectrum with the assumption that the regions with higher fluorescence concentration have larger energy intensity, then the cost function of the inverse problem is modified by the self-prior information, and lastly an iterative Laplacian regularization algorithm is conducted to solve the updated inverse problem and obtains the reconstruction results. Simulations and in vivo experiments on liver reconstruction are carried out to test the performance of the self-prior strategy on organ reconstruction. The organ reconstruction results obtained by the proposed self-prior strategy are closer to the ground truth than those obtained by the iterative Tikhonov regularization (ITKR) method (traditional non-prior strategy). Significant improvements are shown in the evaluation indexes of relative locational error (RLE), relative error (RE) and contrast-to-noise ratio (CNR). The self-prior strategy improves the organ reconstruction results compared with the non-prior strategy and also overcomes the shortcomings of the traditional structural prior strategy. Various applications such as metabolic imaging and pharmacokinetic study can be aided by this strategy.

  11. Fluorescent nanohybrids based on asymmetrical cyanine dyes decorated carbon nanotubes

    OpenAIRE

    Çavuşlar, Özge; Cavuslar, Ozge

    2015-01-01

    In this thesis, we focused on imparting new optical properties to carbon nanotubes (CNTs) to allow their optical detection and visualization in biomedical applications. We investigated the interactions of CNTs and DNA wrapped CNTs with asymmetrical cyanine dye molecules to study the applicability of resulting hybrid materials to fluorescent based systems. When CNTs interacted with asymmetrical cyanine dyes, they constructed a light absorbing nanoarray. However, the fluorescence emission of th...

  12. Inflammation Modulates Murine Venous Thrombosis Resolution In Vivo: Assessment by Multimodal Fluorescence Molecular Imaging

    Science.gov (United States)

    Ripplinger, Crystal M.; Kessinger, Chase W.; Li, Chunqiang; Kim, Jin Won; McCarthy, Jason R.; Weissleder, Ralph; Henke, Peter K.; Lin, Charles P.; Jaffer, Farouc A.

    2012-01-01

    Objective Assessment of thrombus inflammation in vivo could provide new insights into deep vein thrombosis (DVT) resolution. Here we develop and evaluate two integrated fluorescence molecular-structural imaging strategies to quantify DVT-related inflammation and architecture, and to assess the effect of thrombus inflammation on subsequent DVT resolution in vivo. Methods and Results Murine DVT were created with topical 5% FeCl3 application to thigh or jugular veins (n=35). On day 3, mice received macrophage and matrix metalloproteinase (MMP) activity fluorescence imaging agents. On day 4, integrated assessment of DVT inflammation and architecture was performed using confocal fluorescence intravital microscopy (IVM). Day 4 analyses showed robust relationships among in vivo thrombus macrophages, MMP activity, and FITC-dextran deposition (r>0.70, pthrombus inflammation at day 4 predicted the magnitude of DVT resolution at day 6 (pthrombus resolution. PMID:22995524

  13. A disposable evanescent wave fiber optic sensor coated with a molecularly imprinted polymer as a selective fluorescence probe.

    Science.gov (United States)

    Ton, Xuan-Anh; Acha, Victor; Bonomi, Paolo; Tse Sum Bui, Bernadette; Haupt, Karsten

    2015-02-15

    We have developed a disposable evanescent wave fiber optic sensor by coating a molecularly imprinted polymer (MIP) containing a fluorescent signaling group on a 4-cm long polystyrene optical waveguide. The MIP is composed of a naphthalimide-based fluorescent monomer, which shows fluorescence enhancement upon binding with carboxyl-containing molecules. The herbicide 2,4-dichlorophenoxyacetic acid and the mycotoxin citrinin were used as model analytes. The coating of the MIP was either performed ex-situ, by dip-coating the fiber with MIP particles synthesized beforehand, or in-situ by evanescent-wave photopolymerization on the fiber. The sensing element was interrogated with a fiber-coupled spectrofluorimeter. The fiber optic sensor detects targets in the low nM range and exhibits specific and selective recognition over structural analogs and non-related carboxyl-containing molecules. This technology can be extended to other carboxyl-containing analytes, and to a broader spectrum of targets using different fluorescent monomers. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. "Molecular beacon"-hosted thioflavin T: Applications for label-free fluorescent detection of iodide and logic operations.

    Science.gov (United States)

    Li, Yan-Yun; Jiang, Xiao-Qin; Lu, Ling-Fei; Zhang, Min; Shi, Guoyue

    2016-04-01

    In this work, we presented a simple, label-free and rapid-responsive fluorescence assay for iodide (I(-)) detection based on "molecular beacon (MB)"-hosted thioflavin T (ThT), achieving a limit of detection as low as 158 nM. The proposed method exhibited very good selectivity to I(-) ions over other anions interference due to the strong binding force between I(-) ions with Hg(2+). Upon the addition of I(-) ions, it would capture Hg(2+) from a T-Hg(2+)-T complex belonging to the MB-like DNA hairpin structure, which eventually quenched the initial fluorescence as output. In addition, it was successfully applied for operation of an integrated DNA logic gate system and to the determination of I(-) in real samples such as human urine. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. DNA-Based Self-Assembly of Fluorescent Nanodiamonds.

    Science.gov (United States)

    Zhang, Tao; Neumann, Andre; Lindlau, Jessica; Wu, Yuzhou; Pramanik, Goutam; Naydenov, Boris; Jelezko, Fedor; Schüder, Florian; Huber, Sebastian; Huber, Marinus; Stehr, Florian; Högele, Alexander; Weil, Tanja; Liedl, Tim

    2015-08-12

    As a step toward deterministic and scalable assembly of ordered spin arrays we here demonstrate a bottom-up approach to position fluorescent nanodiamonds (NDs) with nanometer precision on DNA origami structures. We have realized a reliable and broadly applicable surface modification strategy that results in DNA-functionalized and perfectly dispersed NDs that were then self-assembled in predefined geometries. With optical studies we show that the fluorescence properties of the nitrogen-vacancy color centers in NDs are preserved during surface modification and DNA assembly. As this method allows the nanoscale arrangement of fluorescent NDs together with other optically active components in complex geometries, applications based on self-assembled spin lattices or plasmon-enhanced spin sensors as well as improved fluorescent labeling for bioimaging could be envisioned.

  16. An extremely sensitive monoboronic acid based fluorescent sensor for glucose

    International Nuclear Information System (INIS)

    Sun Xiangying; Liu Bin; Jiang Yunbao

    2004-01-01

    An extremely sensitive monoboronic acid based fluorescent sensor for glucose was developed. This was carried out by assembling a fluorescent monoboronic acid, 3-aminophenylboronic acid (PBA) indirectly onto gold surface via its electrostatic interaction with cysteine (Cys) that was directly assembled on the gold surface. The formation of self-assembled bilayers (SAB) was confirmed and primarily characterized by cyclic voltammetry and X-ray photoelectron spectra (XPS). The SAB containing PBA was found fluorescent and its fluorescence showed an extremely high sensitivity to the presence of glucose and other monosaccharides such as galactose and fructose with quenching constants at 10 8 M -1 order of magnitude compared to those at 10 2 M -1 in bulk solutions. The quenching constants were found to vary in the order of D-glucose>D-galactose>D-fructose>D-mannose that is different from that in bulk solution which shows the highest binding affinity toward D-fructose and very low sensitivity toward glucose. The reported monoboronic acid based SAB fluorescent sensor showed the highest sensitivity towards glucose with the capacity of detecting saccharides of concentration down to nanomolar level. It was also demonstrated that the fluorescence from PBA/Cys/Au can be easily recovered after each measurement event and therefore also represents a new reusable method for immobilizing reagent in fabricating chemosensors

  17. Synthesis of molecularly imprinted dye-silica nanocomposites with high selectivity and sensitivity: Fluorescent imprinted sensor for rapid and efficient detection of τ-fluvalinate in vodka.

    Science.gov (United States)

    Wang, Yunyun; Wang, Jixiang; Cheng, Rujia; Sun, Lin; Dai, Xiaohui; Yan, Yongsheng

    2018-04-01

    An imprinted fluorescent sensor was fabricated based on SiO 2 nanoparticles encapsulated with a molecularly imprinted polymer containing allyl fluorescein. High fluorine cypermethirin as template molecules, methyl methacrylate as functional monomer, and allyl fluorescein as optical materials synthesized a core-shell fluorescent molecular imprinted sensor, which showed a high and rapid sensitivity and selectivity for the detection of τ-fluvalinate. The sensor presented appreciable sensitivity with a limit of 13.251 nM, rapid detection that reached to equilibrium within 3 min, great linear relationship in the relevant concentration range from 0 to 150 nM, and excellent selectivity over structural analogues. In addition, the fluorescent sensor demonstrated desirable regeneration ability (eight cycling operations). The molecularly imprinted polymers ensured specificity, while the fluorescent dyes provided the stabile sensitivity. Finally, an effective application of the sensor was implemented by the detection of τ-fluvalinate in real samples from vodka. The molecularly imprinted fluorescent sensor showed a promising potential in environmental monitoring and food safety. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Smart phone based bacterial detection using bio functionalized fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Rajendran, Vinoth Kumar; Bakthavathsalam, Padmavathy; Ali, Baquir Mohammed Jaffar

    2014-01-01

    We are describing immunochromatographic test strips with smart phone-based fluorescence readout. They are intended for use in the detection of the foodborne bacterial pathogens Salmonella spp. and Escherichia coli O157. Silica nanoparticles (SiNPs) were doped with FITC and Ru(bpy), conjugated to the respective antibodies, and then used in a conventional lateral flow immunoassay (LFIA). Fluorescence was recorded by inserting the nitrocellulose strip into a smart phone-based fluorimeter consisting of a light weight (40 g) optical module containing an LED light source, a fluorescence filter set and a lens attached to the integrated camera of the cell phone in order to acquire high-resolution fluorescence images. The images were analysed by exploiting the quick image processing application of the cell phone and enable the detection of pathogens within few minutes. This LFIA is capable of detecting pathogens in concentrations as low as 10 5 cfu mL −1 directly from test samples without pre-enrichment. The detection is one order of magnitude better compared to gold nanoparticle-based LFIAs under similar condition. The successful combination of fluorescent nanoparticle-based pathogen detection by LFIAs with a smart phone-based detection platform has resulted in a portable device with improved diagnosis features and having potential application in diagnostics and environmental monitoring. (author)

  19. Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

    Directory of Open Access Journals (Sweden)

    Mathieu L. Lepage

    2015-05-01

    Full Text Available The synthesis and photophysical properties of the first examples of iminosugar clusters based on a BODIPY or a pyrene core are reported. The tri- and tetravalent systems designed as molecular probes and synthesized by way of Cu(I-catalysed azide–alkyne cycloadditions are fluorescent analogues of potent pharmacological chaperones/correctors recently reported in the field of Gaucher disease and cystic fibrosis, two rare genetic diseases caused by protein misfolding.

  20. Fluorescent properties of novel dendrimer dyes based on thiazole orange

    International Nuclear Information System (INIS)

    Fei Xuening; Gu Yingchun; Lan Yunquan; Shi Bin

    2011-01-01

    In this paper, polyamidoamine (PAMAM) dendrimers with active amino group of some generations (G=0.5-2) were prepared from commercial aminoacetaldehyde diethyl acetal by the divergent method. After that, thiazole orange (TO) with -COOH was incorporated with dendrimers of G=1 and 2 to afford novel dendrimer-TO dyes. The fluorescent properties studies showed that the fluorescent intensity of the same concentration of dendrimer-TO (G=2) was higher than that of the dendrimer-TO (G=1), and both of them were much stronger than free TO with -COOH. There was a fluorescent enhancement of the dendrimer dyes compared with free dye. The dendrimer dyes were of well-defined chemical structure,with little aggregation and self-quenching as well as good fluorescence properties of good stability, high intensity and sensitivity, which could be used in labeling cancer cells and further in diagnosis and detection of early-stage tumors. - Highlights: → A kind of dendrimer probe based on TO was designed and synthesized. → Dendrimers showed an obvious fluorescence enhancement compared to free dye. → Dendrimers labeled with BSA also showed fluorescence enhancement. → Dendrimers may be used in diagnosis and detection of early-stage tumors.

  1. Chromophore Structure of Photochromic Fluorescent Protein Dronpa: Acid-Base Equilibrium of Two Cis Configurations.

    Science.gov (United States)

    Higashino, Asuka; Mizuno, Misao; Mizutani, Yasuhisa

    2016-04-07

    Dronpa is a novel photochromic fluorescent protein that exhibits fast response to light. The present article is the first report of the resonance and preresonance Raman spectra of Dronpa. We used the intensity and frequency of Raman bands to determine the structure of the Dronpa chromophore in two thermally stable photochromic states. The acid-base equilibrium in one photochromic state was observed by spectroscopic pH titration. The Raman spectra revealed that the chromophore in this state shows a protonation/deprotonation transition with a pKa of 5.2 ± 0.3 and maintains the cis configuration. The observed resonance Raman bands showed that the other photochromic state of the chromophore is in a trans configuration. The results demonstrate that Raman bands selectively enhanced for the chromophore yield valuable information on the molecular structure of the chromophore in photochromic fluorescent proteins after careful elimination of the fluorescence background.

  2. Fluorescence background subtraction technique for hybrid fluorescence molecular tomography/x-ray computed tomography imaging of a mouse model of early stage lung cancer.

    Science.gov (United States)

    Ale, Angelique; Ermolayev, Vladimir; Deliolanis, Nikolaos C; Ntziachristos, Vasilis

    2013-05-01

    The ability to visualize early stage lung cancer is important in the study of biomarkers and targeting agents that could lead to earlier diagnosis. The recent development of hybrid free-space 360-deg fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) imaging yields a superior optical imaging modality for three-dimensional small animal fluorescence imaging over stand-alone optical systems. Imaging accuracy was improved by using XCT information in the fluorescence reconstruction method. Despite this progress, the detection sensitivity of targeted fluorescence agents remains limited by nonspecific background accumulation of the fluorochrome employed, which complicates early detection of murine cancers. Therefore we examine whether x-ray CT information and bulk fluorescence detection can be combined to increase detection sensitivity. Correspondingly, we research the performance of a data-driven fluorescence background estimator employed for subtraction of background fluorescence from acquisition data. Using mice containing known fluorochromes ex vivo, we demonstrate the reduction of background signals from reconstructed images and sensitivity improvements. Finally, by applying the method to in vivo data from K-ras transgenic mice developing lung cancer, we find small tumors at an early stage compared with reconstructions performed using raw data. We conclude with the benefits of employing fluorescence subtraction in hybrid FMT-XCT for early detection studies.

  3. Fluorescence Quantum Yield Measurements of Fluorescent Proteins: A Laboratory Experiment for a Biochemistry or Molecular Biophysics Laboratory Course

    Science.gov (United States)

    Wall, Kathryn P.; Dillon, Rebecca; Knowles, Michelle K.

    2015-01-01

    Fluorescent proteins are commonly used in cell biology to assess where proteins are within a cell as a function of time and provide insight into intracellular protein function. However, the usefulness of a fluorescent protein depends directly on the quantum yield. The quantum yield relates the efficiency at which a fluorescent molecule converts…

  4. Molecular Detection of Bladder Cancer by Fluorescence Microsatellite Analysis and an Automated Genetic Analyzing System

    Directory of Open Access Journals (Sweden)

    Sarel Halachmi

    2007-01-01

    Full Text Available To investigate the ability of an automated fluorescent analyzing system to detect microsatellite alterations, in patients with bladder cancer. We investigated 11 with pathology proven bladder Transitional Cell Carcinoma (TCC for microsatellite alterations in blood, urine, and tumor biopsies. DNA was prepared by standard methods from blood, urine and resected tumor specimens, and was used for microsatellite analysis. After the primers were fluorescent labeled, amplification of the DNA was performed with PCR. The PCR products were placed into the automated genetic analyser (ABI Prism 310, Perkin Elmer, USA and were subjected to fluorescent scanning with argon ion laser beams. The fluorescent signal intensity measured by the genetic analyzer measured the product size in terms of base pairs. We found loss of heterozygocity (LOH or microsatellite alterations (a loss or gain of nucleotides, which alter the original normal locus size in all the patients by using fluorescent microsatellite analysis and an automated analyzing system. In each case the genetic changes found in urine samples were identical to those found in the resected tumor sample. The studies demonstrated the ability to detect bladder tumor non-invasively by fluorescent microsatellite analysis of urine samples. Our study supports the worldwide trend for the search of non-invasive methods to detect bladder cancer. We have overcome major obstacles that prevented the clinical use of an experimental system. With our new tested system microsatellite analysis can be done cheaper, faster, easier and with higher scientific accuracy.

  5. Infrared images of reflection nebulae and Orion's bar: Fluorescent molecular hydrogen and the 3.3 micron feature

    International Nuclear Information System (INIS)

    Burton, M.G.; Moorhouse, A.; Brand, P.W.J.L.; Roche, P.F.; Geballe, T.R.

    1989-01-01

    Images were obtained of the (fluorescent) molecular hydrogen 1-0 S(1) line, and of the 3.3 micron emission feature, in Orion's Bar and three reflection nebulae. The emission from these species appears to come from the same spatial locations in all sources observed. This suggests that the 3.3 micron feature is excited by the same energetic UV-photons which cause the molecular hydrogen to fluoresce

  6. Extensively Reversible Thermal Transformations of a Bistable, Fluorescence-Switchable Molecular Solid: Entry into Functional Molecular Phase-Change Materials.

    Science.gov (United States)

    Srujana, P; Radhakrishnan, T P

    2015-06-15

    Functional phase-change materials (PCMs) are conspicuously absent among molecular materials in which the various attributes of inorganic solids have been realized. While organic PCMs are primarily limited to thermal storage systems, the amorphous-crystalline transformation of materials like Ge-Sb-Te find use in advanced applications such as information storage. Reversible amorphous-crystalline transformations in molecular solids require a subtle balance between robust supramolecular assembly and flexible structural elements. We report novel diaminodicyanoquinodimethanes that achieve this transformation by interlinked helical assemblies coupled with conformationally flexible alkoxyalkyl chains. They exhibit highly reversible thermal transformations between bistable (crystalline/amorphous) forms, along with a prominent switching of the fluorescence emission energy and intensity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

    Science.gov (United States)

    Favicchio, Rosy; Psycharakis, Stylianos; Schönig, Kai; Bartsch, Dusan; Mamalaki, Clio; Papamatheakis, Joseph; Ripoll, Jorge; Zacharakis, Giannis

    2016-02-01

    Fluorescent proteins and dyes are routine tools for biological research to describe the behavior of genes, proteins, and cells, as well as more complex physiological dynamics such as vessel permeability and pharmacokinetics. The use of these probes in whole body in vivo imaging would allow extending the range and scope of current biomedical applications and would be of great interest. In order to comply with a wide variety of application demands, in vivo imaging platform requirements span from wide spectral coverage to precise quantification capabilities. Fluorescence molecular tomography (FMT) detects and reconstructs in three dimensions the distribution of a fluorophore in vivo. Noncontact FMT allows fast scanning of an excitation source and noninvasive measurement of emitted fluorescent light using a virtual array detector operating in free space. Here, a rigorous process is defined that fully characterizes the performance of a custom-built horizontal noncontact FMT setup. Dynamic range, sensitivity, and quantitative accuracy across the visible spectrum were evaluated using fluorophores with emissions between 520 and 660 nm. These results demonstrate that high-performance quantitative three-dimensional visible light FMT allowed the detection of challenging mesenteric lymph nodes in vivo and the comparison of spectrally distinct fluorescent reporters in cell culture.

  8. Caffeine and sulfadiazine interact differently with human serum albumin: A combined fluorescence and molecular docking study

    Science.gov (United States)

    Islam, Mullah Muhaiminul; Sonu, Vikash K.; Gashnga, Pynsakhiat Miki; Moyon, N. Shaemningwar; Mitra, Sivaprasad

    2016-01-01

    The interaction and binding behavior of the well-known drug sulfadiazine (SDZ) and psychoactive stimulant caffeine (CAF) with human serum albumin (HSA) was monitored by in vitro fluorescence titration and molecular docking calculations under physiological condition. The quenching of protein fluorescence on addition of CAF is due to the formation of protein-drug complex in the ground state; whereas in case of SDZ, the experimental results were explained on the basis of sphere of action model. Although both these compounds bind preferentially in Sudlow's site 1 of the protein, the association constant is approximately two fold higher in case of SDZ (∼4.0 × 104 M-1) in comparison with CAF (∼9.3 × 102 M-1) and correlates well with physico-chemical properties like pKa and lipophilicity of the drugs. Temperature dependent fluorescence study reveals that both SDZ and CAF bind spontaneously with HSA. However, the binding of SDZ with the protein is mainly governed by the hydrophobic forces in contrast with that of CAF; where, the interaction is best explained in terms of electrostatic mechanism. Molecular docking calculation predicts the binding of these drugs in different location of sub-domain IIA in the protein structure.

  9. Cyclopenta[b]naphthalene cyanoacrylate dyes: synthesis and evaluation as fluorescent molecular rotors.

    Science.gov (United States)

    Kocsis, Laura S; Elbel, Kristyna M; Hardigree, Billie A; Brummond, Kay M; Haidekker, Mark A; Theodorakis, Emmanuel A

    2015-03-14

    We describe the design, synthesis and fluorescent profile of a family of environment-sensitive dyes in which a dimethylamino (donor) group is conjugated to a cyanoacrylate (acceptor) unit via a cyclopenta[b]naphthalene ring system. This assembly satisfies the typical D-π-A motif of a fluorescent molecular rotor and exhibits solvatochromic and viscosity-sensitive fluorescence emission. The central naphthalene ring system of these dyes was synthesized via a novel intramolecular dehydrogenative dehydro-Diels-Alder (IDDDA) reaction that permits incorporation of the donor and acceptor groups in variable positions around the aromatic core. A bathochromic shift of excitation and emission peaks was observed with increasing solvent polarity but the dyes exhibited a complex emission pattern with a second red emission band when dissolved in nonpolar solvents. Consistent with other known molecular rotors, the emission intensity increased with increasing viscosity. Interestingly, closer spatial proximity between the donor and the acceptor groups led to decreased viscosity sensitivity combined with an increased quantum yield. This observation indicates that structural hindrance of intramolecular rotation dominates when the donor and acceptor groups are in close proximity. The examined compounds give insight into how excited state intramolecular rotation can be influenced by both the solvent and the chemical structure.

  10. Multimodal fluorescence molecular imaging for in vivo characterization of skin cancer using endogenous and exogenous fluorophores

    Science.gov (United States)

    Miller, Jessica P.; Habimana-Griffin, LeMoyne; Edwards, Tracy S.; Achilefu, Samuel

    2017-06-01

    Similarity of skin cancer with many benign skin pathologies requires reliable methods to detect and differentiate the different types of these lesions. Previous studies have explored the use of disparate optical techniques to identify and estimate the invasive nature of melanoma and basal cell carcinoma with varying outcomes. Here, we used a concerted approach that provides complementary information for rapid screening and characterization of tumors, focusing on squamous cell carcinoma (SCC) of the skin. Assessment of in vivo autofluorescence lifetime (FLT) imaging of endogenous fluorophores that are excitable at longer wavelengths (480 nm) than conventional NADH and FAD revealed a decrease in the short FLT component for SCC compared to normal skin, with mean values of 0.57±0.026 ns and 0.61±0.021 ns, respectively (p=0.004). Subsequent systemic administration of a near-infrared fluorescent molecular probe in SCC bearing mice, followed by the implementation of image processing methods on data acquired from two-dimensional and three-dimensional fluorescence molecular imaging, allowed us to estimate the tumor volume and depth, as well as quantify the fluorescent probe in the tumor. The result suggests the involvement of lipofuscin-like lipopigments and riboflavin in SCC metabolism and serves as a model for staging SCC.

  11. Wireless implantable electronic platform for chronic fluorescent-based biosensors.

    Science.gov (United States)

    Valdastri, Pietro; Susilo, Ekawahyu; Förster, Thilo; Strohhöfer, Christof; Menciassi, Arianna; Dario, Paolo

    2011-06-01

    The development of a long-term wireless implantable biosensor based on fluorescence intensity measurement poses a number of technical challenges, ranging from biocompatibility to sensor stability over time. One of these challenges is the design of a power efficient and miniaturized electronics, enabling the biosensor to move from bench testing to long term validation, up to its final application in human beings. In this spirit, we present a wireless programmable electronic platform for implantable chronic monitoring of fluorescent-based autonomous biosensors. This system is able to achieve extremely low power operation with bidirectional telemetry, based on the IEEE802.15.4-2003 protocol, thus enabling over three-year battery lifetime and wireless networking of multiple sensors. During the performance of single fluorescent-based sensor measurements, the circuit drives a laser diode, for sensor excitation, and acquires the amplified signals from four different photodetectors. In vitro functionality was preliminarily tested for both glucose and calcium monitoring, simply by changing the analyte-binding protein of the biosensor. Electronics performance was assessed in terms of timing, power consumption, tissue exposure to electromagnetic fields, and in vivo wireless connectivity. The final goal of the presented platform is to be integrated in a complete system for blood glucose level monitoring that may be implanted for at least one year under the skin of diabetic patients. Results reported in this paper may be applied to a wide variety of biosensors based on fluorescence intensity measurement.

  12. Design of two and three input molecular logic gates using non-Watson-Crick base pairing-based molecular beacons.

    Science.gov (United States)

    Lin, Jia-Hui; Tseng, Wei-Lung

    2014-03-21

    This study presents a single, resettable, and sensitive molecular beacon (MB) used to operate molecular-scale logic gates. The MB consists of a random DNA sequence, a fluorophore at the 5'-end, and a quencher at the 3'-end. The presence of Hg(2+), Ag(+), and coralyne promoted the formation of stable T-Hg(2+)-T, C-Ag(+)-C, and A2-coralyne-A2 coordination in the MB probe, respectively, thereby driving its conformational change. The metal ion or small molecule-mediated coordination of mismatched DNA brought the fluorophore and the quencher into close proximity, resulting in collisional quenching of fluorescence between the two organic dyes. Because thiol can bind Hg(2+) and remove it from the T-Hg(2+)-T-based MB, adding thiol to a solution of the T-Hg(2+)-T-based MB allowed the fluorophore and the quencher to be widely separated. A similar phenomenon was observed when replacing Hg(2+) with Ag(+). Because Ag(+) strongly binds to iodide, cyanide, and cysteine, they were capable of removing Ag(+) from the C-Ag(+)-C-based MB, restoring the fluorescence of the MB. Moreover, the fluorescence of the A2-coralyne-A2-based MB could be switched on by adding polyadenosine. Using these analytes as inputs and the MB as a signal transducer, we successfully developed a series of two-input, three-input, and set-reset logic gates at the molecular level.

  13. Simultaneous determination of glycols based on fluorescence anisotropy

    International Nuclear Information System (INIS)

    Garcia Sanchez, F.; Navas Diaz, A.; Lopez Guerrero, M.M.

    2007-01-01

    Simultaneous determination of non-fluorescent glycols in mixtures without separation or chemical transformation steps is described. Two methods based in the measure of fluorescence anisotropy of a probe such as fluorescein dissolved in the analyte or analyte mixtures are described. In the first method, the anisotropy spectra of pure and mixtures of analytes are used to quantitative determination (if the fluorophor concentration is in a range where fluorescence intensity is proportional to concentration). In the second method, a calibration curve anisotropy-concentration based on the application of the Perrin equation is established. The methods presented here are capable of directly resolving binary mixtures of non-fluorescent glycols on the basis of differences on the fluorescence anisotropy of a fluorescence tracer. Best analytical performances were obtained by application of the method based on Perrin equation. This method is simple, rapid and allows the determination of mixtures of glycols with reasonable accuracy and precision. Detection limits are limited by the quantum yield and anisotropy values of the tracer in the solvents. Recovery values are related to the differences in anisotropy values of the tracer in the pure solvents. Mixtures of glycerine/ethylene glycol (GL/EG), ethylene glycol/1,2-propane diol (EG/1,2-PPD) and polyethylene glycol 400/1,2-propane diol (PEG 400/1,2-PPD) were analysed and recovery values are within 95-120% in the Perrin method. Relative standard deviation are in the range 1.3-2.9% and detection limits in the range 3.9-8.9%

  14. Molecular Beacon-Based MicroRNA Imaging During Neurogenesis.

    Science.gov (United States)

    Lee, Jonghwan; Kim, Soonhag

    2016-01-01

    The fluorescence monitoring system for examining endogenous microRNA (miRNA) activity in cellular level provides crucial information on not only understanding a critical role of miRNA involving a variety of biological processes, but also evaluating miRNA expression patterns in a noninvasive manner. In this protocol, we report the details of a new procedure for a molecular beacon-based miRNA monitoring system, which includes the illustration scheme for miRNA detection strategy, exogenous miRNA detection, and measurement of endogenous miRNA expression level during neurogenesis. The fluorescence signal of miR-124a beacon quenched by BHQ2 was gradually recovered as increasing concentration of the miR-124a in tube. The functional work of miR-124a beacon was examined in intracellular environment, allowing for the internalization of the miR-124a beacon by lipofectamine, which resulted in activated fluorescent signals of the miR-124a beacon in the HeLa cells after the addition of synthetic miR-124a. The endogenous miR-124a expression level was detected by miR-124a beacon system during neurogenesis, showing brighter fluorescence intensity in cytoplasmic area of P19 cells after induction of neuronal differentiation by retinoic acid. The molecular beacon based-miRNA detection technique could be applicable to the simultaneous visualization of a variety of miRNA expression patterns using different fluorescence dyes. For the study of examining endogenous miRNA expression level using miRNA-beacon system, if cellular differentiation step is already prepared, transfection step of miR-124a beacon into P19 cells, and acquisition of activated fluorescence signal measured by confocal microscope can be conducted approximately within 6 h.

  15. The one-sample PARAFAC approach reveals molecular size distributions of fluorescent components in dissolved organic matter

    DEFF Research Database (Denmark)

    Wünsch, Urban; Murphy, Kathleen R.; Stedmon, Colin

    2017-01-01

    Molecular size plays an important role in dissolved organic matter (DOM) biogeochemistry, but its relationship with the fluorescent fraction of DOM (FDOM) remains poorly resolved. Here high-performance size exclusion chromatography (HPSEC) was coupled to fluorescence emission-excitation (EEM...... but not their spectral properties. Thus, in contrast to absorption measurements, bulk fluorescence is unlikely to reliably indicate the average molecular size of DOM. The one-sample approach enables robust and independent cross-site comparisons without large-scale sampling efforts and introduces new analytical...... opportunities for elucidating the origins and biogeochemical properties of FDOM...

  16. A virus-MIPs fluorescent sensor based on FRET for highly sensitive detection of JEV.

    Science.gov (United States)

    Liang, Caishuang; Wang, Huan; He, Kui; Chen, Chunyan; Chen, Xiaoming; Gong, Hang; Cai, Changqun

    2016-11-01

    Major stumbling blocks in the recognition and detection of virus are the unstable biological recognition element or the complex detection means. Here a fluorescent sensor based on virus-molecular imprinted polymers (virus-MIPs) was designed for specific recognition and highly sensitive detection of Japanese encephalitis virus (JEV). The virus-MIPs were anchored on the surface of silica microspheres modified by fluorescent dye, pyrene-1-carboxaldehyde (PC). The fluorescence intensity of PC can be enhanced by the principle of fluorescence resonance energy transfer (FRET), where virus acted as energy donor and PC acted as energy acceptor. The enhanced fluorescence intensity was proportional to the concentration of virus in the range of 24-960pM, with a limit of detection (LOD, 3σ) of 9.6pM, and the relative standard deviation was 1.99%. In additional, the specificity study confirmed the resultant MIPs has high-selectivity for JEV. This sensor would become a new key for the detection of virus because of its high sensitive, simple operation, high stability and low cost. Copyright © 2016. Published by Elsevier B.V.

  17. In situ detection of atomic and molecular iodine using Resonance and Off-Resonance Fluorescence by Lamp Excitation: ROFLEX

    Directory of Open Access Journals (Sweden)

    J. C. Gómez Martín

    2011-01-01

    Full Text Available We demonstrate a new instrument for in situ detection of atmospheric iodine atoms and molecules based on atomic and molecular resonance and off-resonance ultraviolet fluorescence excited by lamp emission. The instrument combines the robustness, light weight, low power consumption and efficient excitation of radio-frequency discharge light sources with the high sensitivity of the photon counting technique. Calibration of I2 fluorescence is achieved via quantitative detection of the molecule by Incoherent Broad Band Cavity-enhanced Absorption Spectroscopy. Atomic iodine fluorescence signal is calibrated by controlled broad band photolysis of known I2 concentrations in the visible spectral range at atmospheric pressure. The instrument has been optimised in laboratory experiments to reach detection limits of 1.2 pptv for I atoms and 13 pptv for I2, for S/N = 1 and 10 min of integration time. The ROFLEX system has been deployed in a field campaign in northern Spain, representing the first concurrent observation of ambient mixing ratios of iodine atoms and molecules in the 1–350 pptv range.

  18. Imaging performance of a hybrid x-ray computed tomography-fluorescence molecular tomography system using priors.

    Science.gov (United States)

    Ale, Angelique; Schulz, Ralf B; Sarantopoulos, Athanasios; Ntziachristos, Vasilis

    2010-05-01

    The performance is studied of two newly introduced and previously suggested methods that incorporate priors into inversion schemes associated with data from a recently developed hybrid x-ray computed tomography and fluorescence molecular tomography system, the latter based on CCD camera photon detection. The unique data set studied attains accurately registered data of high spatially sampled photon fields propagating through tissue along 360 degrees projections. Approaches that incorporate structural prior information were included in the inverse problem by adding a penalty term to the minimization function utilized for image reconstructions. Results were compared as to their performance with simulated and experimental data from a lung inflammation animal model and against the inversions achieved when not using priors. The importance of using priors over stand-alone inversions is also showcased with high spatial sampling simulated and experimental data. The approach of optimal performance in resolving fluorescent biodistribution in small animals is also discussed. Inclusion of prior information from x-ray CT data in the reconstruction of the fluorescence biodistribution leads to improved agreement between the reconstruction and validation images for both simulated and experimental data.

  19. Photolysis study of octyl p-methoxycinnamate loaded microemulsion by molecular fluorescence and chemometric approach

    Science.gov (United States)

    Nascimento, Danielle Silva; Insausti, Matías; Band, Beatriz Susana Fernández; Grünhut, Marcos

    2018-02-01

    Octyl p-methoxycinnamate (OMC) is one of the most widely used sunscreen agents. However, the efficiency of OMC as UV filter over time is affected due to the formation of the cis-isomer which presents a markedly lower extinction coefficient (εcis = 12,600 L mol- 1 cm- 1 at 291 nm) than the original trans-isomer (εtrans = 24,000 L mol- 1 cm- 1 at 310 nm). In this work, a novel carrier for OMC based on an oil-in-water microemulsion is proposed in order to improve the photostability of this sunscreen. The formulation was composed of 29.2% (w/w) of a 3:1 mixture of ethanol (co-surfactant) and decaethylene glycol mono-dodecyl ether (surfactant), 1.5% (w/w) of oleic acid (oil phase) and 69.2% (w/w) of water. This microemulsion was prepared in a simple way, under moderate stirring at 25 °C and using acceptable, biocompatible and accessible materials for topical use. OMC was incorporated in the vehicle at a final concentration of 5.0% (w/w), taking into account the maximum permitted levels established by international norms. Then, a photolysis study of the loaded formulation was performed using a continuous flow system. The direct photolysis was monitored over time by molecular fluorescence. The recorded spectra data between 370 y 490 nm were analyzed by multivariate curve resolution-alternating least squares algorithm. The kinetic rate constants corresponding to the photolysis of the trans-OMC were calculated from the concentration profiles, resulting in 0.0049 s- 1 for the trans-OMC loaded microemulsion and 0.0131 s- 1 for the trans-OMC in aqueous media. These results demonstrate a higher photostability of the trans-OMC when loaded in the proposed vehicle with respect to the free trans-OMC in aqueous media.

  20. Temperature dependence of the anisotropy of fluorescence in ring molecular systems

    International Nuclear Information System (INIS)

    Herman, Pavel; Barvik, Ivan

    2007-01-01

    The time dependence of the anisotropy of fluorescence after an impulsive excitation in the molecular ring (resembling the B850 ring of the purple bacterium Rhodopseudomonas acidophila) is calculated. Fast fluctuations of the environment are simulated by dynamic disorder and slow fluctuations by uncorrelated static disorder. Without dynamic disorder modest degrees of static disorder are sufficient to cause the experimentally found initial drop of the anisotropy on a sub-100 fs time scale. In the present investigation we are comparing results for the time-dependent optical anisotropy of the molecular ring for four models of the uncorrelated static disorder: Gaussian disorder in the local energies (model A), Gaussian disorder in the transfer integrals (model B), Gaussian disorder in radial positions of molecules (model C) and Gaussian disorder in angular positions of molecules (model D). Both types of disorder-static and dynamic-are taken into account simultaneously

  1. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  2. Comparative Phenotypical and Molecular Analyses of Arabidopsis Grown under Fluorescent and LED Light

    Directory of Open Access Journals (Sweden)

    Franka Seiler

    2017-06-01

    Full Text Available Comparative analyses of phenotypic and molecular traits of Arabidopsis thaliana grown under standardised conditions is still a challenge using climatic devices supplied with common light sources. These are in most cases fluorescent lights, which have several disadvantages such as heat production at higher light intensities, an invariable spectral output, and relatively rapid “ageing”. This results in non-desired variations of growth conditions and lowers the comparability of data acquired over extended time periods. In this study, we investigated the growth behaviour of Arabidopsis Col0 under different light conditions, applying fluorescent compared to LED lamps, and we conducted physiological as well as gene expression analyses. By changing the spectral composition and/or light intensity of LEDs we can clearly influence the growth behaviour of Arabidopsis and thereby study phenotypic attributes under very specific light conditions that are stable and reproducible, which is not necessarily given for fluorescent lamps. By using LED lights, we can also roughly mimic the sun light emission spectrum, enabling us to study plant growth in a more natural-like light set-up. We observed distinct growth behaviour under the different light regimes which was reflected by physiological properties of the plants. In conclusion, LEDs provide variable emission spectra for studying plant growth under defined, stable light conditions.

  3. Fluorescence in situ hybridization and molecular studies in infertile men with dysplasia of the fibrous sheath.

    Science.gov (United States)

    Baccetti, Baccio; Collodel, Giulia; Gambera, Laura; Moretti, Elena; Serafini, Francesca; Piomboni, Paola

    2005-07-01

    To perform fluorescence in situ hybridization (FISH) and molecular analysis in patients with the genetic sperm defect "dysplasia of the fibrous sheath" (DFS). Retrospective study. Regional Referral Center for Male Infertility, Siena, Italy. Twelve infertile patients with DFS sperm defects. Family history, lymphocytic karyotype, physical and hormonal assays, semen analysis. The DFS sperm phenotype was defined by light, fluorescent, and electron microscopy. Sperm chromosomal constitution was examined by FISH. Gene deletions were tested by polymerase chain reaction. The genetic sperm defect DFS was determined by transmission and scanning electron microscopy. Immunofluorescence staining of A-kinase anchoring protein 4 (AKAP4) showed a moderate and diffuse signal, revealing a disorganized and incompletely assembled fibrous sheath. In 11 of 12 DFS patients, polymerase chain reaction for detecting the presence of partial sequence of AKAP4/AKAP3 binding regions gave positive results. Fluorescence in situ hybridization was performed in decondensed sperm nuclei with probes for chromosomes 18, X, and Y. The mean disomy frequency of chromosome 18 was in the normal range, whereas the mean disomy frequencies of sex chromosomes and diploidies were twice those of controls. These results should be considered when DFS sperm are used in assisted reproductive technology, owing to the high risk of transmission of chromosomal unbalance and of DFS sperm defects to male offspring.

  4. Observation of divergent La3+ ion dilute effect in two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RExLa1−x–EBTC (RE3+=Eu3+ or Tb3+; EBTC4−=1,1′-ethynebenzene-3,3′,5,5′-etracarboxylate)

    International Nuclear Information System (INIS)

    Zhai, Lu; Zhang, Wen-Wei; Ren, Xiao-Ming; Zuo, Jing-Lin

    2015-01-01

    The lanthanide metal-organic frameworks (MOFs) [Ln 2 (EBTC) 1.5 (CH 3 OH) 4 ]·6H 2 O are isostructural to each other, where EBTC 4− =1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; Ln 3+ =La 3+ , Eu 3+ and Tb 3+ ; and the corresponding MOF is abbreviated as Ln–EBTC. MOFs Eu–EBTC and Tb–EBTC emit intense red and green luminescence (visible by bare eyes), respectively. The molecular alloys of Eu x La 1−x –EBTC and Tb x La 1−x –EBTC have been successfully prepared by mixing Eu 3+ /Tb 3+ and La 3+ salts with the desired molar ratio in the starting material. Two series of Eu x La 1−x –EBTC and Tb x La 1−x –EBTC molecular alloys are isomorphic to the parent Ln–EBTC MOFs, while exhibit divergent La 3+ ion diluting effect, namely, with increasing the relative amount of La 3+ , the intensity of characteristic emission arising from Tb 3+ ion monotonely increases in Tb x La 1−x –EBTC molecular alloys, whereas that of Eu 3+ ion shows non-monotone decrease in Eu x La 1−x –EBTC molecular alloys. The possible origin is discussed for such a divergent behavior between Eu x La 1−x –EBTC and Tb x La 1−x –EBTC molecular alloys. - Graphical abstract: Two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RE x La 1−x –EBTC (RE 3+ =Eu 3+ or Tb 3+ ; EBTC 4− =1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate) have been successfully prepared by mixing Eu 3+ /Tb 3+ and La 3+ salts with the desired molar ratio in the starting material and showed photoluminescence property with divergent La 3+ ion dilute effect. - Highlights: • 3-D molecular alloys of Eu x La 1−x –EBTC and Tb x La 1−x –EBTC were prepared. • They are isomorphic to the parent Ln–EBTC MOFs. • They show photoluminescence property with divergent La 3+ ion diluting effect. • The possible origin is discussed for such a divergent behavior

  5. A novel Schiff-base as a Cu(II) ion fluorescent sensor in aqueous solution

    Science.gov (United States)

    Gündüz, Z. Yurtman; Gündüz, C.; Özpınar, C.; Urucu, O. Aydın

    2015-02-01

    A new fluorescent Cu(II) sensor (L) obtained from the Schiff base of 5,5‧-methylene-bis-salicylaldehyde with amidol (2,4-diaminophenol) was synthesized and characterized by FT-IR, MS, 1H NMR, 13C NMR techniques. In the presence of pH 6.5 (KHPO4-Na2HPO4) buffer solutions, copper reacted with L to form a stable 2:1 complex. Fluorescence spectroscopic study showed that Schiff base is highly sensitive towards Cu(II) over other metal ions (K+, Na+, Al3+, Ni2+, Co2+, Fe3+, Zn2+, Pb2+) in DMSO/H2O (30%, v/v). The sensor L was successfully applied to the determination of copper in standard reference material. The structural properties and molecular orbitals of the complex formed between L and Cu2+ ions were also investigated using quantum chemical computations.

  6. Highly Sensitive Ratiometric Fluorescent Sensor for Trinitrotoluene Based on the Inner Filter Effect between Gold Nanoparticles and Fluorescent Nanoparticles.

    Science.gov (United States)

    Lu, Hongzhi; Quan, Shuai; Xu, Shoufang

    2017-11-08

    In this work, we developed a simple and sensitive ratiometric fluorescent assay for sensing trinitrotoluene (TNT) based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent nanoparticles (RFNs), which was designed by hybridizing green emissive carbon dots (CDs) and red emissive quantum dots (QDs) into a silica sphere as a fluorophore pair. AuNPs in their dispersion state can be a powerful absorber to quench CDs, while the aggregated AuNPs can quench QDs in the IFE-based fluorescent assays as a result of complementary overlap between the absorption spectrum of AuNPs and emission spectrum of RFNs. As a result of the fact that TNT can induce the aggregation of AuNPs, with the addition of TNT, the fluorescent of QDs can be quenched, while the fluorescent of CDs would be recovered. Then, ratiometric fluorescent detection of TNT is feasible. The present IFE-based ratiometric fluorescent sensor can detect TNT ranging from 0.1 to 270 nM, with a detection limit of 0.029 nM. In addition, the developed method was successfully applied to investigate TNT in water and soil samples with satisfactory recoveries ranging from 95 to 103%, with precision below 4.5%. The simple sensing approach proposed here could improve the sensitivity of colorimetric analysis by changing the ultraviolet analysis to ratiometric fluorescent analysis and promote the development of a dual-mode detection system.

  7. In vivo quantification of fluorescent molecular markers in real-time by ratio Imaging for diagnostic screening and image-guided surgery

    NARCIS (Netherlands)

    Bogaards, A.; Sterenborg, H. J. C. M.; Trachtenberg, J.; Wilson, B. C.; Lilge, L.

    2007-01-01

    Future applications of "molecular diagnostic screening" and "molecular image-guided surgery" will demand images of molecular markers with high resolution and high throughput (similar to >= 30 frames/second). MRI, SPECT, PET, optical fluorescence tomography, hyper-spectral fluorescence imaging, and

  8. ICT-Isomerization-Induced Turn-On Fluorescence Probe with a Large Emission Shift for Mercury Ion: Application in Combinational Molecular Logic.

    Science.gov (United States)

    Bhatta, Sushil Ranjan; Mondal, Bijan; Vijaykumar, Gonela; Thakur, Arunabha

    2017-10-02

    A unique turn-on fluorescent device based on a ferrocene-aminonaphtholate derivative specific for Hg 2+ cation was developed. Upon binding with Hg 2+ ion, the probe shows a dramatic fluorescence enhancement (the fluorescence quantum yield increases 58-fold) along with a large red shift of 68 nm in the emission spectrum. The fluorescence enhancement with a red shift may be ascribed to the combinational effect of C═N isomerization and an extended intramolecular charge transfer (ICT) mechanism. The response was instantaneous with a detection limit of 2.7 × 10 -9 M. Upon Hg 2+ recognition, the ferrocene/ferrocenium redox peak was anodically shifted by ΔE 1/2 = 72 mV along with a "naked eye" color change from faint yellow to pale orange for this metal cation. Further, upon protonation of the imine nitrogen, the present probe displays a high fluorescence output due to suppression of the C═N isomerization process. Upon deprotonation using strong base, the fluorescence steadily decreases, which indicates that H + and OH - can be used to regulate the off-on-off fluorescence switching of the present probe. Density functional theory studies revealed that the addition of acid leads to protonation of the imine N (according to natural bond orbital analysis), and the resulting iminium proton forms a strong H-bond (2.307 Å) with one of the triazole N atoms to form a five-membered ring, which makes the molecule rigid; hence, enhancement of the ICT process takes place, thereby leading to a fluorescence enhancement with a red shift. The unprecedented combination of H + , OH - , and Hg 2+ ions has been used to generate a molecular system exhibiting the INHIBIT-OR combinational logic operation.

  9. Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography--part 2: image reconstruction.

    Science.gov (United States)

    Correia, Teresa; Koch, Maximilian; Ale, Angelique; Ntziachristos, Vasilis; Arridge, Simon

    2016-02-21

    Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. We propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. Furthermore, structural information can be incorporated into the image reconstruction with PAD-WT to improve image quality and resolution. In this case, the weights used to average voxels in the image are calculated using the structural image, instead of the fluorescence image. The regularisation strength depends on both structural and fluorescence images, which guarantees that the method can preserve fluorescence information even when it is not structurally visible in the anatomical images. In part 1, we tested the method using a denoising problem. Here, we use simulated and in vivo mouse fDOT data to assess the algorithm performance. Our results show that the proposed PAD-WT method provides high quality and noise free images, superior to those obtained using AD.

  10. Fluorescence and NMR spectroscopy together with molecular simulations reveal amphiphilic characteristics of a Burkholderia biofilm exopolysaccharide.

    Science.gov (United States)

    Kuttel, Michelle M; Cescutti, Paola; Distefano, Marco; Rizzo, Roberto

    2017-06-30

    Biofilms are a collective mode of bacterial life in which a self-produced matrix confines cells in close proximity to each other. Biofilms confer many advantages, including protection from chemicals (including antibiotics), entrapment of useful extracellular enzymes and nutrients, as well as opportunities for efficient recycling of molecules from dead cells. Biofilm matrices are aqueous gel-like structures composed of polysaccharides, proteins, and DNA stabilized by intermolecular interactions that may include non-polar connections. Recently, polysaccharides extracted from biofilms produced by species of the Burkholderia cepacia complex were shown to possess clusters of rhamnose, a 6-deoxy sugar with non-polar characteristics. Molecular dynamics simulations are well suited to characterizing the structure and dynamics of polysaccharides, but only relatively few such studies exist of their interaction with non-polar molecules. Here we report an investigation into the hydrophobic properties of the exopolysaccharide produced by Burkholderia multivorans strain C1576. Fluorescence experiments with two hydrophobic fluorescent probes established that this polysaccharide complexes hydrophobic species, and NMR experiments confirmed these interactions. Molecular simulations to model the hydrodynamics of the polysaccharide and the interaction with guest species revealed a very flexible, amphiphilic carbohydrate chain that has frequent dynamic interactions with apolar molecules; both hexane and a long-chain fatty acid belonging to the quorum-sensing system of B. multivorans were tested. A possible role of the non-polar domains of the exopolysaccharide in facilitating the diffusion of aliphatic species toward specific targets within the biofilm aqueous matrix is proposed. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. A fluorescence-based rapid screening assay for cytotoxic compounds

    International Nuclear Information System (INIS)

    Montoya, Jessica; Varela-Ramirez, Armando; Estrada, Abril; Martinez, Luis E.; Garza, Kristine; Aguilera, Renato J.

    2004-01-01

    A simple fluorescence-based assay was developed for the rapid screening of potential cytotoxic compounds generated by combinatorial chemistry. The assay is based on detection of nuclear green fluorescent protein (GFP) staining of a human cervical cancer cell line (HeLa) carrying an integrated histone H2B-GFP fusion gene. Addition of a cytotoxic compound to the HeLa-GFP cells results in the eventual degradation of DNA and loss of the GFP nuclear fluorescence. Using this assay, we screened 11 distinct quinone derivatives and found that several of these compounds were cytotoxic. These compounds are structurally related to plumbagin an apoptosis-inducing naphthoquinone isolated from Black Walnut. In order to determine the mechanism by which cell death was induced, we performed additional experiments with the most cytotoxic quinones. These compounds were found to induce morphological changes (blebbing and nuclear condensation) consistent with induction of apoptosis. Additional tests revealed that the cytotoxic compounds induce both necrotic and apoptotic modes of death

  12. Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

    OpenAIRE

    Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

    2015-01-01

    We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based mi...

  13. Fluorescent bioaerosol particle, molecular tracer, and fungal spore concentrations during dry and rainy periods in a semi-arid forest

    Directory of Open Access Journals (Sweden)

    M. I. Gosselin

    2016-12-01

    Full Text Available Bioaerosols pose risks to human health and agriculture and may influence the evolution of mixed-phase clouds and the hydrological cycle on local and regional scales. The availability and reliability of methods and data on the abundance and properties of atmospheric bioaerosols, however, are rather limited. Here we analyze and compare data from different real-time ultraviolet laser/light-induced fluorescence (UV-LIF instruments with results from a culture-based spore sampler and offline molecular tracers for airborne fungal spores in a semi-arid forest in the southern Rocky Mountains of Colorado. Commercial UV-APS (ultraviolet aerodynamic particle sizer and WIBS-3 (wideband integrated bioaerosol sensor, version 3 instruments with different excitation and emission wavelengths were utilized to measure fluorescent aerosol particles (FAPs during both dry weather conditions and periods heavily influenced by rain. Seven molecular tracers of bioaerosols were quantified by analysis of total suspended particle (TSP high-volume filter samples using a high-performance anion-exchange chromatography system with pulsed amperometric detection (HPAEC-PAD. From the same measurement campaign, Huffman et al. (2013 previously reported dramatic increases in total and fluorescent particle concentrations during and immediately after rainfall and also showed a strong relationship between the concentrations of FAPs and ice nuclei (Huffman et al., 2013; Prenni et al., 2013. Here we investigate molecular tracers and show that during rainy periods the atmospheric concentrations of arabitol (35.2 ± 10.5 ng m−3 and mannitol (44.9 ± 13.8 ng m−3 were 3–4 times higher than during dry periods. During and after rain, the correlations between FAP and tracer mass concentrations were also significantly improved. Fungal spore number concentrations on the order of 104 m−3, accounting for 2–5 % of TSP mass during dry periods and 17–23 % during rainy

  14. Fluorescence based fiber optic and planar waveguide biosensors. A review

    International Nuclear Information System (INIS)

    Benito-Peña, Elena; Valdés, Mayra Granda; Glahn-Martínez, Bettina; Moreno-Bondi, Maria C.

    2016-01-01

    The application of optical biosensors, specifically those that use optical fibers and planar waveguides, has escalated throughout the years in many fields, including environmental analysis, food safety and clinical diagnosis. Fluorescence is, without doubt, the most popular transducer signal used in these devices because of its higher selectivity and sensitivity, but most of all due to its wide versatility. This paper focuses on the working principles and configurations of fluorescence-based fiber optic and planar waveguide biosensors and will review biological recognition elements, sensing schemes, as well as some major and recent applications, published in the last ten years. The main goal is to provide the reader a general overview of a field that requires the joint collaboration of researchers of many different areas, including chemistry, physics, biology, engineering, and material science. - Highlights: • Principles, configurations and fluorescence techniques using fiber optic and planar waveguide biosensors are discussed. • The biorecognition elements and sensing schemes used in fiber optic and planar waveguide platforms are reviewed. • Some major and recent applications of fiber optic and planar waveguide biosensors are introduced.

  15. Fluorescence based fiber optic and planar waveguide biosensors. A review

    Energy Technology Data Exchange (ETDEWEB)

    Benito-Peña, Elena [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain); Valdés, Mayra Granda [Department of Analytical Chemistry, Faculty of Chemistry, University of La Habana, 10400 La Habana (Cuba); Glahn-Martínez, Bettina [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain); Moreno-Bondi, Maria C., E-mail: mcmbondi@quim.ucm.es [Department of Analytical Chemistry, Faculty of Chemistry, Complutense University, 28040 Madrid (Spain)

    2016-11-02

    The application of optical biosensors, specifically those that use optical fibers and planar waveguides, has escalated throughout the years in many fields, including environmental analysis, food safety and clinical diagnosis. Fluorescence is, without doubt, the most popular transducer signal used in these devices because of its higher selectivity and sensitivity, but most of all due to its wide versatility. This paper focuses on the working principles and configurations of fluorescence-based fiber optic and planar waveguide biosensors and will review biological recognition elements, sensing schemes, as well as some major and recent applications, published in the last ten years. The main goal is to provide the reader a general overview of a field that requires the joint collaboration of researchers of many different areas, including chemistry, physics, biology, engineering, and material science. - Highlights: • Principles, configurations and fluorescence techniques using fiber optic and planar waveguide biosensors are discussed. • The biorecognition elements and sensing schemes used in fiber optic and planar waveguide platforms are reviewed. • Some major and recent applications of fiber optic and planar waveguide biosensors are introduced.

  16. FMT-XCT: in vivo animal studies with hybrid fluorescence molecular tomography-X-ray computed tomography.

    Science.gov (United States)

    Ale, Angelique; Ermolayev, Vladimir; Herzog, Eva; Cohrs, Christian; de Angelis, Martin Hrabé; Ntziachristos, Vasilis

    2012-06-01

    The development of hybrid optical tomography methods to improve imaging performance has been suggested over a decade ago and has been experimentally demonstrated in animals and humans. Here we examined in vivo performance of a camera-based hybrid fluorescence molecular tomography (FMT) system for 360° imaging combined with X-ray computed tomography (XCT). Offering an accurately co-registered, information-rich hybrid data set, FMT-XCT has new imaging possibilities compared to stand-alone FMT and XCT. We applied FMT-XCT to a subcutaneous 4T1 tumor mouse model, an Aga2 osteogenesis imperfecta model and a Kras lung cancer mouse model, using XCT information during FMT inversion. We validated in vivo imaging results against post-mortem planar fluorescence images of cryoslices and histology data. Besides offering concurrent anatomical and functional information, FMT-XCT resulted in the most accurate FMT performance to date. These findings indicate that addition of FMT optics into the XCT gantry may be a potent upgrade for small-animal XCT systems.

  17. A Far-ultraviolet Fluorescent Molecular Hydrogen Emission Map of the Milky Way Galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Young-Soo; Min, Kyoung-Wook [Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Seon, Kwang-Il; Han, Wonyong [Korea Astronomy and Space Science Institute (KASI), 776 Daedeokdae-ro, Yuseong-gu, Daejeon, 305-348 (Korea, Republic of); Edelstein, Jerry, E-mail: stspeak@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA, 94720 (United States)

    2017-08-01

    We present the far-ultraviolet (FUV) fluorescent molecular hydrogen (H{sub 2}) emission map of the Milky Way Galaxy obtained with FIMS/SPEAR covering ∼76% of the sky. The extinction-corrected intensity of the fluorescent H{sub 2} emission has a strong linear correlation with the well-known tracers of the cold interstellar medium (ISM), including color excess E(B–V) , neutral hydrogen column density N (H i), and H α emission. The all-sky H{sub 2} column density map was also obtained using a simple photodissociation region model and interstellar radiation fields derived from UV star catalogs. We estimated the fraction of H{sub 2} ( f {sub H2}) and the gas-to-dust ratio (GDR) of the diffuse ISM. The f {sub H2} gradually increases from <1% at optically thin regions where E(B–V) < 0.1 to ∼50% for E(B–V)  = 3. The estimated GDR is ∼5.1 × 10{sup 21} atoms cm{sup −2} mag{sup −1}, in agreement with the standard value of 5.8 × 10{sup 21} atoms cm{sup −2} mag{sup −1}.

  18. Fluorescent Molecular Rotor-in-Paraffin Waxes for Thermometry and Biometric Identification.

    Science.gov (United States)

    Jin, Young-Jae; Dogra, Rubal; Cheong, In Woo; Kwak, Giseop

    2015-07-08

    Novel thermoresponsive sensor systems consisting of a molecular rotor (MR) and paraffin wax (PW) were developed for various thermometric and biometric identification applications. Polydiphenylacetylenes (PDPAs) coupled with long alkyl chains were used as MRs, and PWs of hydrocarbons having 16-20 carbons were utilized as phase-change materials. The PDPAs were successfully dissolved in the molten PWs and did not act as an impurity that prevents phase transition of the PWs. These PDPA-in-PW hybrids had almost the same enthalpies and phase-transition temperatures as the corresponding pure PWs. The hybrids exhibited highly reversible fluorescence (FL) changes at the critical temperatures during phase transition of the PWs. These hybrids were impregnated into common filter paper in the molten state by absorption or were encapsulated into urea resin to enhance their mechanical integrity and cyclic stability during repeated use. The wax papers could be utilized in highly advanced applications including FL image writing/erasing, an array-type thermo-indicator, and fingerprint/palmprint identification. The present findings should facilitate the development of novel fluorescent sensor systems for biometric identification and are potentially applicable for biological and biomedical thermometry.

  19. An off-on fluorescence probe targeting mitochondria based on oxidation-reduction response for tumor cell and tissue imaging

    Science.gov (United States)

    Yao, Hanchun; Cao, Li; Zhao, Weiwei; Zhang, Suge; Zeng, Man; Du, Bin

    2017-10-01

    In this study, a tumor-targeting poly( d, l-lactic-co-glycolic acid) (PLGA) loaded "off-on" fluorescent probe nanoparticle (PFN) delivery system was developed to evaluate the region of tumor by off-on fluorescence. The biodegradability of the nanosize PFN delivery system readily released the probe under tumor acidic conditions. The probe with good biocompatibility was used to monitor the intracellular glutathione (GSH) of cancer cells and selectively localize to mitochondria for tumor imaging. The incorporated tumor-targeting probe was based on the molecular photoinduced electron transfer (PET) mechanism preventing fluorescence ("off" state) and could be easily released under tumor acidic conditions. However, the released tumor-targeting fluorescence probe molecule was selective towards GSH with high selectivity and an ultra-sensitivity for the mitochondria of cancer cells and tissues significantly increasing the probe molecule fluorescence signal ("on" state). The tumor-targeting fluorescence probe showed sensitivity to GSH avoiding interference from cysteine and homocysteine. The PFNs could enable fluorescence-guided cancer imaging during cancer therapy. This work may expand the biological applications of PFNs as a diagnostic reagent, which will be beneficial for fundamental research in tumor imaging. [Figure not available: see fulltext.

  20. Preparation and characterization of alginate based-fluorescent magnetic nanoparticles for fluorescence/magnetic resonance multimodal imaging applications

    Science.gov (United States)

    Kwon, Yong-Su; Choi, Kee-Bong; Lim, Hyungjun; Lee, Sunghwi; Lee, Jae-Jong

    2018-06-01

    Simple and versatile methodologies have been reported that customize the surface of superparamagnetic iron oxide (SPIO) nanoparticles and impart additional fluorescence capabilities to these contrast agents. Herein, we present the rational design, synthesis, characterization, and biological applications of a new magnetic-based fluorescent probe. The dual modality imaging protocol was developed by labeling fluorophore with alginate natural polymers that have excellent biocompatibility and biodegradability, and using gelification method to form nanocomposites containing SPIO. The formation of alginate-based fluorescent magnetic (AFM) nanoparticles was observed in spherical and elliptical forms with a diameter of less than 500 nm by a transmission electron microscope (TEM). The fluorescent wavelength band in the range of 560 nm was also confirmed in the UV–visible spectrophotometer. In this study, we demonstrate that the multi-tasking design of AFM nanoparticles provides an ideal platform for building balanced dual-image probes of magnetic resonance imaging and optical imaging.

  1. Bases moleculares de las leucemias agudas

    Directory of Open Access Journals (Sweden)

    G. Martínez Antuña

    2006-04-01

    Full Text Available El gran desarrollo de la biología molecular en los últimos años ha contribuido a un importante avance en los conocimientos relacionados con las bases moleculares de las leucemias agudas (LA. Ademas de profundizar en la biología de estas enfermedades y conocer las bases moleculares, ha renido también gran impacto en mejorar el resultado de los tratamientos y disminuir la toxicidad de las terapias.

  2. Sensitive turn-on fluorescent detection of tartrazine based on fluorescence resonance energy transfer.

    Science.gov (United States)

    Huang, Sheng Tian; Shi, Yan; Li, Nian Bing; Luo, Hong Qun

    2012-01-18

    We introduce a sensitive, rapid, label-free and general fluorescent method for the determination of tartrazine by competitive binding to reduced graphene oxide (rGO) against fluorescein, and the fluorescence recovery upon fluorescein desorption from rGO provides a quantitative readout for tartrazine, giving a detection limit of 0.53 ng mL(-1).

  3. A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

    Directory of Open Access Journals (Sweden)

    Stefanie Wolfram

    2014-10-01

    Full Text Available Molecular probes are widely used tools in chemical biology that allow tracing of bioactive metabolites and selective labeling of proteins and other biomacromolecules. A common structural motif for such probes consists of a reporter that can be attached by copper(I-catalyzed 1,2,3-triazole formation between terminal alkynes and azides to a reactive headgroup. Here we introduce the synthesis and application of the new thiazole-based, azide-tagged reporter 4-(3-azidopropoxy-5-(4-bromophenyl-2-(pyridin-2-ylthiazole for fluorescence, UV and mass spectrometry (MS detection. This small fluorescent reporter bears a bromine functionalization facilitating the automated data mining of electrospray ionization MS runs by monitoring for its characteristic isotope signature. We demonstrate the universal utility of the reporter for the detection of an alkyne-modified small molecule by LC–MS and for the visualization of a model protein by in-gel fluorescence. The novel probe advantageously compares with commercially available azide-modified fluorophores and a brominated one. The ease of synthesis, small size, stability, and the universal detection possibilities make it an ideal reporter for activity-based protein profiling and functional metabolic profiling.

  4. A Cu2+-selective fluorescent chemosensor based on BODIPY with two pyridine ligands and logic gate

    Science.gov (United States)

    Huang, Liuqian; Zhang, Jing; Yu, Xiaoxiu; Ma, Yifan; Huang, Tianjiao; Shen, Xi; Qiu, Huayu; He, Xingxing; Yin, Shouchun

    2015-06-01

    A novel near-infrared fluorescent chemosensor based on BODIPY (Py-1) has been synthesized and characterized. Py-1 displays high selectivity and sensitivity for sensing Cu2+ over other metal ions in acetonitrile. Upon addition of Cu2+ ions, the maximum absorption band of Py-1 in CH3CN displays a red shift from 603 to 608 nm, which results in a visual color change from pink to blue. When Py-1 is excited at 600 nm in the presence of Cu2+, the fluorescent emission intensity of Py-1 at 617 nm is quenched over 86%. Notably, the complex of Py-1-Cu2+ can be restored with the introduction of EDTA or S2-. Consequently, an IMPLICATION logic gate at molecular level operating in fluorescence mode with Cu2+ and S2- as chemical inputs can be constructed. Finally, based on the reversible and reproducible system, a nanoscale sequential memory unit displaying "Writing-Reading-Erasing-Reading" functions can be integrated.

  5. Improving limited-projection-angle fluorescence molecular tomography using a co-registered x-ray computed tomography scan.

    Science.gov (United States)

    Radrich, Karin; Ale, Angelique; Ermolayev, Vladimir; Ntziachristos, Vasilis

    2012-12-01

    We examine the improvement in imaging performance, such as axial resolution and signal localization, when employing limited-projection-angle fluorescence molecular tomography (FMT) together with x-ray computed tomography (XCT) measurements versus stand-alone FMT. For this purpose, we employed living mice, bearing a spontaneous lung tumor model, and imaged them with FMT and XCT under identical geometrical conditions using fluorescent probes for cancer targeting. The XCT data was employed, herein, as structural prior information to guide the FMT reconstruction. Gold standard images were provided by fluorescence images of mouse cryoslices, providing the ground truth in fluorescence bio-distribution. Upon comparison of FMT images versus images reconstructed using hybrid FMT and XCT data, we demonstrate marked improvements in image accuracy. This work relates to currently disseminated FMT systems, using limited projection scans, and can be employed to enhance their performance.

  6. First molecular identification of the transgene red fluorescent protein (RFP in transgenic ornamental zebrafish (Danio rerio introduced in Peru

    Directory of Open Access Journals (Sweden)

    Carlos Scotto

    2013-09-01

    Full Text Available In this paper the transgenic fluorescent red, orange and pink zebra fish (Danio rerio, found in local aquariums in Peru, were identified using the PCR technique to amplify the transgene RFP sea anemone belonging to Discosoma spp. The gene expression of the red fluorescent protein (RFP transgene was found to determine different gradients-of-bioluminescence (shades in color in each GMO fish analyzed. We performed sequence analysis of the two variants of the RFP along with six variants of the existing fluorescent protein GFP from the Genbank, this could help identify quickly if they are new genes or variants thereof as these novel fluorescent proteins may be introduced in aquatic GMO in the future. Thus, developing and improving biosecurity measures through its timely detection at the molecular genetic level.

  7. Intrinsic fluorescence of protein in turbid media using empirical relation based on Monte Carlo lookup table

    Science.gov (United States)

    Einstein, Gnanatheepam; Udayakumar, Kanniyappan; Aruna, Prakasarao; Ganesan, Singaravelu

    2017-03-01

    Fluorescence of Protein has been widely used in diagnostic oncology for characterizing cellular metabolism. However, the intensity of fluorescence emission is affected due to the absorbers and scatterers in tissue, which may lead to error in estimating exact protein content in tissue. Extraction of intrinsic fluorescence from measured fluorescence has been achieved by different methods. Among them, Monte Carlo based method yields the highest accuracy for extracting intrinsic fluorescence. In this work, we have attempted to generate a lookup table for Monte Carlo simulation of fluorescence emission by protein. Furthermore, we fitted the generated lookup table using an empirical relation. The empirical relation between measured and intrinsic fluorescence is validated using tissue phantom experiments. The proposed relation can be used for estimating intrinsic fluorescence of protein for real-time diagnostic applications and thereby improving the clinical interpretation of fluorescence spectroscopic data.

  8. Hybrid Integrated Silicon Microfluidic Platform for Fluorescence Based Biodetection

    Directory of Open Access Journals (Sweden)

    André Darveau

    2007-09-01

    Full Text Available The desideratum to develop a fully integrated Lab-on-a-chip device capable ofrapid specimen detection for high throughput in-situ biomedical diagnoses and Point-of-Care testing applications has called for the integration of some of the novel technologiessuch as the microfluidics, microphotonics, immunoproteomics and Micro ElectroMechanical Systems (MEMS. In the present work, a silicon based microfluidic device hasbeen developed for carrying out fluorescence based immunoassay. By hybrid attachment ofthe microfluidic device with a Spectrometer-on-chip, the feasibility of synthesizing anintegrated Lab-on-a-chip type device for fluorescence based biosensing has beendemonstrated. Biodetection using the microfluidic device has been carried out usingantigen sheep IgG and Alexafluor-647 tagged antibody particles and the experimentalresults prove that silicon is a compatible material for the present application given thevarious advantages it offers such as cost-effectiveness, ease of bulk microfabrication,superior surface affinity to biomolecules, ease of disposability of the device etc., and is thussuitable for fabricating Lab-on-a-chip type devices.

  9. Relating Trp-Glu dipeptide fluorescence to molecular conformation: the role of the discrete Chi 1 and Chi 2 angles.

    Science.gov (United States)

    Eisenberg, Azaria Solomon; Juszczak, Laura J

    2013-07-05

    Molecular dynamics (MD), coupled with fluorescence data for charged dipeptides of tryptophanyl glutamic acid (Trp-Glu), reveal a detailed picture of how specific conformation affects fluorescence. Fluorescence emission spectra and time-resolved emission measurements have been collected for all four charged species. MD simulations 20 to 30 ns in length have also been carried out for the Trp-Glu species, as simulation provides aqueous phase conformational data that can be correlated with the fluorescence data. The calculations show that each dipeptide species is characterized by a similar set of six, discrete Chi 1, Chi 2 dihedral angle pairs. The preferred Chi 1 angles--60°, 180°, and 300°--play the significant role in positioning the terminal amine relative to the indole ring. A Chi 1 angle of 60° results in the arching of the backbone over the indole ring and no interaction of the ring with the terminal amine. Chi 1 values of 180° and 300° result in an extension of the backbone away from the indole ring and a NH3 cation-π interaction with indole. This interaction is believed responsible for charge transfer quenching. Two fluorescence lifetimes and their corresponding amplitudes correlate with the Chi 1 angle probability distribution for all four charged Trp-Glu dipeptides. Fluorescence emission band maxima are also consistent with the proposed pattern of terminal amine cation quenching of fluorescence. Copyright © 2013 Wiley Periodicals, Inc.

  10. A 3D imaging system integrating photoacoustic and fluorescence orthogonal projections for anatomical, functional and molecular assessment of rodent models

    Science.gov (United States)

    Brecht, Hans P.; Ivanov, Vassili; Dumani, Diego S.; Emelianov, Stanislav Y.; Anastasio, Mark A.; Ermilov, Sergey A.

    2018-03-01

    We have developed a preclinical 3D imaging instrument integrating photoacoustic tomography and fluorescence (PAFT) addressing known deficiencies in sensitivity and spatial resolution of the individual imaging components. PAFT is designed for simultaneous acquisition of photoacoustic and fluorescence orthogonal projections at each rotational position of a biological object, enabling direct registration of the two imaging modalities. Orthogonal photoacoustic projections are utilized to reconstruct large (21 cm3 ) volumes showing vascularized anatomical structures and regions of induced optical contrast with spatial resolution exceeding 100 µm. The major advantage of orthogonal fluorescence projections is significant reduction of background noise associated with transmitted or backscattered photons. The fluorescence imaging component of PAFT is used to boost detection sensitivity by providing low-resolution spatial constraint for the fluorescent biomarkers. PAFT performance characteristics were assessed by imaging optical and fluorescent contrast agents in tissue mimicking phantoms and in vivo. The proposed PAFT technology will enable functional and molecular volumetric imaging using fluorescent biomarkers, nanoparticles, and other photosensitive constructs mapped with high fidelity over robust anatomical structures, such as skin, central and peripheral vasculature, and internal organs.

  11. A Dansyl-Rhodamine Based Fluorescent Probe for Detection of Hg2+ and Cu2.

    Science.gov (United States)

    Yuan, Shizhuang; Su, Wei; Wang, Enju

    2017-09-01

    A novel fluorescent probe based on dansyl-appended rhodamine B was developed. The probe can selectively recognize and sense Hg2+ and Cu2+ from other common metal ions by showing unique fluorescence and absorption characteristics. In MeCN/HEPES buffer solution, the probe gives a ratiometric fluorescent response to Hg2+, which was ascribed to the fluorescence resonance energy transfer from dansyl moiety to the ring-opened rhodamine B moiety, while the presence of Cu2+ causes fluorescence quenching. Beside the fluorescence change, the presence of Cu2+ and Hg2+ can induce intensive absorption at about 555 nm, which resulted in a color change from colorless to pink.

  12. Noninvasive imaging of multiple myeloma using near infrared fluorescent molecular probe

    Science.gov (United States)

    Hathi, Deep; Zhou, Haiying; Bollerman-Nowlis, Alex; Shokeen, Monica; Akers, Walter J.

    2016-03-01

    Multiple myeloma is a plasma cell malignancy characterized by monoclonal gammopathy and osteolytic bone lesions. Multiple myeloma is most commonly diagnosed in late disease stages, presenting with pathologic fracture. Early diagnosis and monitoring of disease status may improve quality of life and long-term survival for multiple myeloma patients from what is now a devastating and fatal disease. We have developed a near-infrared targeted fluorescent molecular probe with high affinity to the α4β1 integrin receptor (VLA-4)overexpressed by a majority of multiple myeloma cells as a non-radioactive analog to PET/CT tracer currently being developed for human diagnostics. A near-infrared dye that emits about 700 nm was conjugated to a high affinity peptidomimmetic. Binding affinity and specificity for multiple myeloma cells was investigated in vitro by tissue staining and flow cytometry. After demonstration of sensitivity and specificity, preclinical optical imaging studies were performed to evaluate tumor specificity in murine subcutaneous and metastatic multiple myeloma models. The VLA-4-targeted molecular probe showed high affinity for subcutaneous MM tumor xenografts. Importantly, tumor cells specific accumulation in the bone marrow of metastatic multiple myeloma correlated with GFP signal from transfected cells. Ex vivo flow cytometry of tumor tissue and bone marrow further corroborated in vivo imaging data, demonstrating the specificity of the novel agent and potential for quantitative imaging of multiple myeloma burden in these models.

  13. Biochemical activity of a fluorescent dye rhodamine 6G: Molecular modeling, electrochemical, spectroscopic and thermodynamic studies.

    Science.gov (United States)

    Al Masum, Abdulla; Chakraborty, Maharudra; Ghosh, Soumen; Laha, Dipranjan; Karmakar, Parimal; Islam, Md Maidul; Mukhopadhyay, Subrata

    2016-11-01

    Interaction of CT DNA with Rhodamine 6G (R6G) has been studied using molecular docking, electrochemical, spectroscopic and thermodynamic methods. From the study, it was illustrated that Rhodamine 6G binds to the minor groove of CT DNA. The binding was cooperative in nature. Circular voltametric study showed significant change in peak current and peak potential due to complexation. All the studies showed that the binding constant was in the order of 10 6 M -1 . Circular dichroic spectra showed significant conformational change on binding and DNA unwind during binding. Thermodynamic study showed that binding was favored by negative enthalpy and positive entropy change. From thermodynamic study it was also observed that several positive and negative free energies played significant role during binding and the unfavorable conformational free energy change was overcame by highly negative hydrophobic and salt dependent free energy changes. The experimental results were further validated using molecular docking study and the effect of structure on binding has been studied theoretically. From docking study it was found that the hydrophobic interaction and hydrogen bonds played a significant role during binding. The dye was absorbed by cell and this phenomenon was studied using fluorescent microscope. Cell survivability test showed that the dye active against Human Breast Cancer cells MDA-MB 468. ROS study showed that the activity is due to the production of reactive oxygen. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Dansyl Based "Turn-On" Fluorescent Sensor for Cu2+ Ion Detection and the Application to Living Cell Imaging.

    Science.gov (United States)

    Nasomphan, Weerachai; Tangboriboonrat, Pramuan; Smanmoo, Srung

    2017-11-01

    A new "turn-on" fluorescent chemosensor based on dansyl derivative was prepared for Cu 2+ ion sensing. Hydroxyl, imine and azomethine groups in Schiff base derived compound 1 were deliberately introduced for facilitating the binding of Cu 2+ ion. Of screen metal ions, compound 1 showed a high degree of selectivity toward Cu 2+ ion. Other interfering metal ions did not affect the fluorescence intensity of compound 1, except Hg 2+ and Fe 3+ ions exhibited a significant degree of fluorescence quenching. Upon binding of Cu 2+ ion, compound 1 displayed a chelation enhanced fluorescence (CHEF) resulting in increasing of the fluorescence intensity. The molecular optimized geometry indicated the binding ratio between compound 1 and Cu 2+ ion at 1:1 with the binding constant of 1.68 × 10 - 7 M - 1 . The optimized condition for sensing ability of compound 1 with a detection limit of 5 × 10 - 7 M was found at the physiological pH 7.2 with the excitation wavelength of 366 nm. Due to no cytotoxicity and good photophysical properties, compound 1 was extended its application for the detection of Cu 2+ ion in Vero cells. Compound 1 could be potentially used as an intracellular fluorescent chemosensor for tracking Cu 2+ ion. Graphical Abstract.

  15. Assisted Interpretation of Laser-Induced Fluorescence Spectra of Egg-Based Binding Media Using Total Emission Fluorescence Spectroscopy

    International Nuclear Information System (INIS)

    Anglos, D.; Nevin, A.

    2006-01-01

    Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to auto fluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total emission fluorescence spectra where a series of consecutive emission spectra are recorded over a specific range. Results using nanosecond UV laser sources for LIF of egg-based binding media are presented which are rationalised following comparisons with total emission spectra. Specifically, fluorescence is assigned to tryptophan and oxidation products of amino acids; in the case of egg yolk, fatty-acid polymerisation and age-related degradation products account for the formation of fluorophores.

  16. Charge-transfer-based terbium MOF nanoparticles as fluorescent pH sensor for extreme acidity.

    Science.gov (United States)

    Qi, Zewan; Chen, Yang

    2017-01-15

    Newly emerged metal organic frameworks (MOFs) have aroused the great interest in designing functional materials by means of its flexible structure and component. In this study, we used lanthanide Tb 3+ ions and small molecular ligands to design and assemble a kind of pH-sensitive MOF nanoparticle based on intramolecular-charge-transfer effect. This kind of made-to-order MOF nanoparticle for H + is highly specific and sensitive and could be used to fluorescently indicate pH value of strong acidic solution via preset mechanism through luminescence of Tb 3+ . The long luminescence lifetime of Tb 3+ allows eliminating concomitant non-specific fluorescence by time-revised fluorescence techniques, processing an advantage in sensing H + in biological media with strong autofluorescence. Our method showed a great potential of MOF structures in designing and constructing sensitive sensing materials for specific analytes directly via the assembly of functional ions/ligands. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography—part 1: technical principles

    International Nuclear Information System (INIS)

    Correia, Teresa; Arridge, Simon

    2016-01-01

    Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. In this two-part paper, we propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. The proposed method combines the nonlocal means (NLM), AD and wavelet shrinkage methods, which are image processing methods. Therefore, in this first paper, we used a denoising test problem to analyse the performance of the new method. Our results show that the proposed PAD-WT method provides better results than the AD or NLM methods alone. The efficacy of the method for fDOT image reconstruction problem is evaluated in part 2. (paper)

  18. Molecular recognition of DNA-protein complexes: A straightforward method combining scanning force and fluorescence microscopy

    NARCIS (Netherlands)

    H. Sanchez (Humberto); R. Kanaar (Roland); C. Wyman (Claire)

    2010-01-01

    textabstractCombining scanning force and fluorescent microscopy allows simultaneous identification of labeled biomolecules and analysis of their nanometer level architectural arrangement. Fluorescent polystyrene nano-spheres were used as reliable objects for alignment of optical and topographic

  19. BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide

    Directory of Open Access Journals (Sweden)

    Ludmila Škorpilová

    2017-07-01

    Full Text Available Like thapsigargin, which is undergoing clinical trials, trilobolide is a natural product with promising anticancer and anti-inflammatory properties. Similar to thapsigargin, it has limited aqueous solubility that strongly reduces its potential medicinal applications. The targeted delivery of hydrophobic drugs can be achieved using liposome-based carriers. Therefore, we designed a traceable liposomal drug delivery system for trilobolide. The fluorescent green-emitting dye BODIPY, cholesterol and trilobolide were used to create construct 6. The liposomes were composed of dipalmitoyl-3-trimethylammoniumpropane and phosphatidylethanolamine. The whole system was characterized by atomic force microscopy, the average size of the liposomes was 150 nm in width and 30 nm in height. We evaluated the biological activity of construct 6 and its liposomal formulation, both of which showed immunomodulatory properties in primary rat macrophages. The uptake and intracellular distribution of construct 6 and its liposomal formulation was monitored by means of live-cell fluorescence microscopy in two cancer cell lines. The encapsulation of construct 6 into the liposomes improved the drug distribution in cancer cells and was followed by cell death. This new liposomal trilobolide derivative not only retains the biological properties of pure trilobolide, but also enhances the bioavailability, and thus has potential for the use in theranostic applications.

  20. Development and cytotoxicity of Schiff base derivative as a fluorescence probe for the detection of L-Arginine

    Science.gov (United States)

    Shang, Xuefang; Li, Jie; Guo, Kerong; Ti, Tongyu; Wang, Tianyun; Zhang, Jinlian

    2017-04-01

    Inspired from biological counter parts, chemical modification of Schiff base derivatives with function groups may provide a highly efficient method to detect amino acids. Therefore, a fluorescent probe involving Schiff base and hydroxyl group has been designed and prepared, which showed high response and specificity for Arginine (Arg) among normal eighteen standard kinds of amino acids (Alanine, Valine, Leucine, Isoleucine, Methionine, Asparticacid, Glutamicacid, Arginine, Glycine, Serine, Threonine, Asparagine, Phenylalanine, Histidine, Tryptophan, Proline, Lysine, Glutamine, Tyrosine and Cysteine). Furthermore, theoretical investigation further illustrated the possible binding mode in the host-guest interaction and the roles of molecular frontier orbitals in molecular interplay. In addition, the synthesized fluorescent probe exhibited high binding ability for Arg and low cytotoxicity to MCF-7 cells over a concentration range of 0-200 μg mL-1 which can be also used as a biosensor for the Arg detection in vivo.

  1. ESIPT-Based Photoactivatable Fluorescent Probe for Ratiometric Spatiotemporal Bioimaging

    Directory of Open Access Journals (Sweden)

    Xiaohong Zhou

    2016-10-01

    Full Text Available Photoactivatable fluorophores have become an important technique for the high spatiotemporal resolution of biological imaging. Here, we developed a novel photoactivatable probe (PHBT, which is based on 2-(2-hydroxyphenylbenzothiazole (HBT, a small organic fluorophore known for its classic luminescence mechanism through excited-state intramolecular proton transfer (ESIPT with the keto form and the enol form. After photocleavage, PHBT released a ratiometric fluorophore HBT, which showed dual emission bands with more than 73-fold fluorescence enhancement at 512 nm in buffer and more than 69-fold enhancement at 452 nm in bovine serum. The probe displayed a high ratiometric imaging resolution and is believed to have a wide application in biological imaging.

  2. Cell-based lipid flippase assay employing fluorescent lipid derivatives

    DEFF Research Database (Denmark)

    Jensen, Maria Stumph; Costa, Sara; Günther-Pomorski, Thomas

    2016-01-01

    P-type ATPases in the P4 subfamily (P4-ATPases) are transmembrane proteins unique for eukaryotes that act as lipid flippases, i.e., to translocate phospholipids from the exofacial to the cytofacial monolayer of cellular membranes. While initially characterized as aminophospholipid translocases, s...... flippase activities in the plasma membrane of cells, using yeast as an example.......P-type ATPases in the P4 subfamily (P4-ATPases) are transmembrane proteins unique for eukaryotes that act as lipid flippases, i.e., to translocate phospholipids from the exofacial to the cytofacial monolayer of cellular membranes. While initially characterized as aminophospholipid translocases......, studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates. Here, we describe an assay based on fluorescent lipid derivatives to monitor and characterize lipid...

  3. Anatomical image-guided fluorescence molecular tomography reconstruction using kernel method

    Science.gov (United States)

    Baikejiang, Reheman; Zhao, Yue; Fite, Brett Z.; Ferrara, Katherine W.; Li, Changqing

    2017-01-01

    Abstract. Fluorescence molecular tomography (FMT) is an important in vivo imaging modality to visualize physiological and pathological processes in small animals. However, FMT reconstruction is ill-posed and ill-conditioned due to strong optical scattering in deep tissues, which results in poor spatial resolution. It is well known that FMT image quality can be improved substantially by applying the structural guidance in the FMT reconstruction. An approach to introducing anatomical information into the FMT reconstruction is presented using the kernel method. In contrast to conventional methods that incorporate anatomical information with a Laplacian-type regularization matrix, the proposed method introduces the anatomical guidance into the projection model of FMT. The primary advantage of the proposed method is that it does not require segmentation of targets in the anatomical images. Numerical simulations and phantom experiments have been performed to demonstrate the proposed approach’s feasibility. Numerical simulation results indicate that the proposed kernel method can separate two FMT targets with an edge-to-edge distance of 1 mm and is robust to false-positive guidance and inhomogeneity in the anatomical image. For the phantom experiments with two FMT targets, the kernel method has reconstructed both targets successfully, which further validates the proposed kernel method. PMID:28464120

  4. Direct reconstruction of pharmacokinetic parameters in dynamic fluorescence molecular tomography by the augmented Lagrangian method

    Science.gov (United States)

    Zhu, Dianwen; Zhang, Wei; Zhao, Yue; Li, Changqing

    2016-03-01

    Dynamic fluorescence molecular tomography (FMT) has the potential to quantify physiological or biochemical information, known as pharmacokinetic parameters, which are important for cancer detection, drug development and delivery etc. To image those parameters, there are indirect methods, which are easier to implement but tend to provide images with low signal-to-noise ratio, and direct methods, which model all the measurement noises together and are statistically more efficient. The direct reconstruction methods in dynamic FMT have attracted a lot of attention recently. However, the coupling of tomographic image reconstruction and nonlinearity of kinetic parameter estimation due to the compartment modeling has imposed a huge computational burden to the direct reconstruction of the kinetic parameters. In this paper, we propose to take advantage of both the direct and indirect reconstruction ideas through a variable splitting strategy under the augmented Lagrangian framework. Each iteration of the direct reconstruction is split into two steps: the dynamic FMT image reconstruction and the node-wise nonlinear least squares fitting of the pharmacokinetic parameter images. Through numerical simulation studies, we have found that the proposed algorithm can achieve good reconstruction results within a small amount of time. This will be the first step for a combined dynamic PET and FMT imaging in the future.

  5. Skin fluorescence model based on the Monte Carlo technique

    Science.gov (United States)

    Churmakov, Dmitry Y.; Meglinski, Igor V.; Piletsky, Sergey A.; Greenhalgh, Douglas A.

    2003-10-01

    The novel Monte Carlo technique of simulation of spatial fluorescence distribution within the human skin is presented. The computational model of skin takes into account spatial distribution of fluorophores following the collagen fibers packing, whereas in epidermis and stratum corneum the distribution of fluorophores assumed to be homogeneous. The results of simulation suggest that distribution of auto-fluorescence is significantly suppressed in the NIR spectral region, while fluorescence of sensor layer embedded in epidermis is localized at the adjusted depth. The model is also able to simulate the skin fluorescence spectra.

  6. Brilliant molecular nanocrystals emerging from sol-gel thin films: towards a new generation of fluorescent biochips

    International Nuclear Information System (INIS)

    Dubuisson, E; Monnier, V; Sanz-Menez, N; Ibanez, A; Boury, B; Usson, Y; Pansu, R B

    2009-01-01

    To develop highly sensitive biosensors, we made directly available to biological aqueous solutions organic nanocrystals previously grown in the pores of sol-gel films. Through the controlled dissolution of the sol-gel surface, we obtained emerging nanocrystals that remained strongly anchored to the sol-gel coating for good mechanical stability of the final sensing device. We demonstrated that in the presence of a solution of DNA functionalized with a molecular probe, the nanocrystal fluorescence is strongly quenched by Foerster resonance energy transfer thus opening the way towards very sensitive fluorescent biosensors through biomolecules grafted onto fluorescent nanocrystals. Finally, this controlled dissolution, involving weak concentrated NaOH solution, is a generic process that can be used for the thinning of any kind of sol-gel layer.

  7. Anomalous doping of a molecular crystal monitored with confocal fluorescence microscopy: Terrylene in a p-terphenyl crystal

    Science.gov (United States)

    Białkowska, Magda; Deperasińska, Irena; Makarewicz, Artur; Kozankiewicz, Bolesław

    2017-09-01

    Highly terrylene doped single crystals of p-terphenyl, obtained by co-sublimation of both components, showed bright spots in the confocal fluorescence images. Polarization of the fluorescence excitation spectra, blinking and bleaching, and saturation behavior allowed us to attribute them to single molecules of terrylene anomalously embedded between two neighbor layers of the host crystal, in the (a,b) plane. Such an orientation of terrylene molecules results in much more efficient absorption and collection of the fluorescence photons than in the case of previously investigated molecules embedded in the substitution sites. The above conclusion was supported by quantum chemistry calculations. We postulate that the kind of doping considered in this work should be possible in other molecular crystals where the host molecules are organized in a herringbone pattern.

  8. Mechanical Damage Detection of Indonesia Local Citrus Based on Fluorescence Imaging

    Science.gov (United States)

    Siregar, T. H.; Ahmad, U.; Sutrisno; Maddu, A.

    2018-05-01

    Citrus experienced physical damage in peel will produce essential oils that contain polymethoxylated flavone. Polymethoxylated flavone is fluorescence substance; thus can be detected by fluorescence imaging. This study aims to study the fluorescence spectra characteristic and to determine the damage region in citrus peel based on fluorescence image. Pulung citrus from Batu district, East Java, as a famous citrus production area in Indonesia, was used in the experiment. It was observed that the image processing could detect the mechanical damage region. Fluorescence imaging can be used to classify the citrus into two categories, sound and defect citruses.

  9. Ensemble empirical mode decomposition based fluorescence spectral noise reduction for low concentration PAHs

    Science.gov (United States)

    Wang, Shu-tao; Yang, Xue-ying; Kong, De-ming; Wang, Yu-tian

    2017-11-01

    A new noise reduction method based on ensemble empirical mode decomposition (EEMD) is proposed to improve the detection effect for fluorescence spectra. Polycyclic aromatic hydrocarbons (PAHs) pollutants, as a kind of important current environmental pollution source, are highly oncogenic. Using the fluorescence spectroscopy method, the PAHs pollutants can be detected. However, instrument will produce noise in the experiment. Weak fluorescent signals can be affected by noise, so we propose a way to denoise and improve the detection effect. Firstly, we use fluorescence spectrometer to detect PAHs to obtain fluorescence spectra. Subsequently, noises are reduced by EEMD algorithm. Finally, the experiment results show the proposed method is feasible.

  10. Imaging of pharmacokinetic rates of indocyanine green in mouse liver with a hybrid fluorescence molecular tomography/x-ray computed tomography system.

    Science.gov (United States)

    Zhang, Guanglei; Liu, Fei; Zhang, Bin; He, Yun; Luo, Jianwen; Bai, Jing

    2013-04-01

    Pharmacokinetic rates have the potential to provide quantitative physiological and pathological information for biological studies and drug development. Fluorescence molecular tomography (FMT) is an attractive imaging tool for three-dimensionally resolving fluorophore distribution in small animals. In this letter, pharmacokinetic rates of indocyanine green (ICG) in mouse liver are imaged with a hybrid FMT and x-ray computed tomography (XCT) system. A recently developed FMT method using structural priors from an XCT system is adopted to improve the quality of FMT reconstruction. In the in vivo experiments, images of uptake and excretion rates of ICG in mouse liver are obtained, which can be used to quantitatively evaluate liver function. The accuracy of the results is validated by a fiber-based fluorescence measurement system.

  11. Flexibility of cold- and heat-adapted subtilisin-like serine proteinases evaluated with fluorescence quenching and molecular dynamics

    DEFF Research Database (Denmark)

    Sigtryggsdóttir, Asta Rós; Papaleo, Elena; Thorbjarnardóttir, Sigríður H.

    2014-01-01

    activity of cold adapted enzymes when compared to homologues from thermophiles, reflects their higher molecular flexibility. To assess a potential difference in molecular flexibility between the two homologous proteinases, we have measured their Trp fluorescence quenching by acrylamide at different......The subtilisin-like serine proteinases, VPR, from a psychrotrophic Vibrio species and aqualysin I (AQUI) from the thermophile Thermus aquaticus, are structural homologues, but differ significantly with respect to stability and catalytic properties. It has been postulated that the higher catalytic...... to Trp (Y191W). A lower quenching effect of acrylamide on the intrinsic fluorescence of the thermophilic AQUI_Y191W was observed at all temperatures measured (10-55°C), suggesting that it possesses a more rigid structure than VPR. The MD analysis (Cα rmsf profiles) showed that even though VPR and AQUI...

  12. Detection of influenza A virus based on fluorescence resonance energy transfer from quantum dots to carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Tian Junping [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Zhao Huimin, E-mail: zhaohuim@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Liu Meng; Chen Yaqiong; Quan Xie [Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer The quantum dots-ssDNA probe was designed for the determination of virus DNA. Black-Right-Pointing-Pointer The fluorescence of quantum dots was effectively quenched by carbon nanotubes. Black-Right-Pointing-Pointer The addition of target H5N1 DNA restored the quenched fluorescence of quantum dots. Black-Right-Pointing-Pointer The proposed method exhibited high sensitivity and good selectivity for H5N1 DNA. - Abstract: In this paper, a simple and sensitive approach for H5N1 DNA detection was described based on the fluorescence resonance energy transfer (FRET) from quantum dots (QDs) to carbon nanotubes (CNTs) in a QDs-ssDNA/oxCNTs system, in which the QDs (CdTe) modified with ssDNA were used as donors. In the initial stage, with the strong interaction between ssDNA and oxCNTs, QDs fluorescence was effectively quenched. Upon the recognition of the target, the effective competitive bindings of it to QDs-ssDNA occurred, which decreased the interactions between the QDs-ssDNA and oxCNTs, leading to the recovery of the QDs fluorescence. The recovered fluorescence of QDs was linearly proportional to the concentration of the target in the range of 0.01-20 {mu}M with a detection limit of 9.39 nM. Moreover, even a single-base mismatched target with the same concentration of target DNA can only recover a limited low fluorescence of QDs, illustrating the good anti-interference performance of this QDs-ssDNA/oxCNTs system. This FRET platform in the QDs-ssDNA/oxCNTs system was facilitated to the simple, sensitive and quantitative detection of virus nucleic acids and could have a wide range of applications in molecular diagnosis.

  13. Novel chalcone-based fluorescent human histamine H3 receptor ligands as pharmacological tools

    Directory of Open Access Journals (Sweden)

    Holger eStark

    2012-03-01

    Full Text Available Novel fluorescent chalcone-based ligands at human histamine H3 receptors (hH3R have been designed, synthesized and characterized. Compounds described are non-imidazole analogues of ciproxifan with a tetralone motif. Tetralones as chemical precursors and related fluorescent chalcones exhibit affinities at hH3R in the same concentration range like that of the reference antagonist ciproxifan (hH3R pKi value of 7.2. Fluorescence characterization of our novel ligands shows emission maxima about 570 nm for yellow fluorescent chalcones and ≥600 nm for the red fluorescent derivatives. Interferences to cellular autofluorescence could be excluded. All synthesized chalcone compounds could be taken to visualize hH3R proteins in stably transfected HEK-293 cells using confocal laser scanning fluorescence microscopy. These novel fluorescent ligands possess high potential to be used as pharmacological tools for hH3R visualization in different tissues.

  14. SERS and fluorescence-based ultrasensitive detection of mercury in water.

    Science.gov (United States)

    Makam, Pandeeswar; Shilpa, Rohilla; Kandjani, Ahmad Esmaielzadeh; Periasamy, Selvakannan R; Sabri, Ylias Mohammad; Madhu, Chilakapati; Bhargava, Suresh Kumar; Govindaraju, Thimmaiah

    2018-02-15

    The development of reliable and ultrasensitive detection marker for mercury ions (Hg 2+ ) in drinking water is of great interest for toxicology assessment, environmental protection and human health. Although many Hg 2+ detection methods have been developed, only few offer sensitivities below 1pM. Herein, we describe a simple histidine (H) conjugated perylene diimide (PDI) bolaamphiphile (HPH) as a dual-responsive optical marker to develop highly selective and sensitive probe as visible (sol-to-gel transformation), fluorescence and SERS-based Hg 2+ sensor platform in the water. Remarkably, HPH as a SERS marker supported on Au deposited monodispersed nanospheres monolayers (Au-MNM) of polystyrene offers an unprecedented selectivity and the best ever reported detection limit (LOD) of 60 attomolar (aM, 0.01 parts-per-quadrillion (ppq)) for Hg 2+ in water. This is ten orders of magnitude lower than the United States Environmental Protection Agency (USEPA) tolerance limit of Hg 2+ in drinking water (10nM, 2 ppb). This simple and effective design principle of host-guest interactions driven fluorescence and SERS-based detection may inspire the future molecular engineering strategies for the development of ultrasensitive toxic analyte sensor platforms. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A recombinant estrogen receptor fragment-based homogeneous fluorescent assay for rapid detection of estrogens.

    Science.gov (United States)

    Wang, Dan; Xie, Jiangbi; Zhu, Xiaocui; Li, Jinqiu; Zhao, Dongqin; Zhao, Meiping

    2014-05-15

    In this work, we demonstrate a novel estrogenic receptor fragment-based homogeneous fluorescent assay which enables rapid and sensitive detection of 17β-estradiol (E2) and other highly potent estrogens. A modified human estrogenic receptor fragment (N-His × 6-hER270-595-C-Strep tag II) has been constructed that contains amino acids 270-595 of wild-type human estrogenic receptor α (hER270-595) and two specific tags (6 × His and Strep tag II) fused to the N and C terminus, respectively. The designed receptor protein fragment could be easily produced by prokaryotic expression with high yield and high purity. The obtained protein exhibits high binding affinity to E2 and the two tags greatly facilitate the application of the recombinant protein. Taking advantage of the unique spectroscopic properties of coumestrol (CS), a fluorescent phytoestrogen, a CS/hER270-595-based fluorescent assay has been developed which can sensitively respond to E2 within 1.0 min with a linear working range from 0.1 to 20 ng/mL and a limit of detection of 0.1 ng/mL. The assay was successfully applied for rapid detection of E2 in the culture medium of rat hippocampal neurons. The method also holds great potential for high-throughput monitoring the variation of estrogen levels in complex biological fluids, which is crucial for investigation of the molecular basis of various estrogen-involved processes. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. DNA-functionalized gold nanoparticle-based fluorescence polarization for the sensitive detection of silver ions.

    Science.gov (United States)

    Wang, Gongke; Wang, Shuangli; Yan, Changling; Bai, Guangyue; Liu, Yufang

    2018-04-05

    Despite their practical applications, Ag + ions are environmental pollutants and affect human health. So the effective detection methods of Ag + ions are imperative. Herein, we developed a simple, sensitive, selective, and cost-effective fluorescence polarization sensor for Ag + detection in aqueous solution using thiol-DNA-functionalized gold nanoparticles (AuNPs). In this sensing strategy, Ag + ions can specifically interact with a cytosine-cytosine (CC) mismatch in DNA duplexes and form stable metal-mediated cytosine-Ag + -cytosine (C-Ag + -C) base pairs. The formation of the C-Ag + -C complex results in evident changes in the molecular volume and fluorescence polarization signal. To achieve our aims, we prepared two complementary DNA strands containing C-base mismatches (probe A: 5'-SH-A 10 -TACCACTCCTCAC-3' and probe B: 5'-TCCTCACCAGTCCTA-FAM-3'). The stable hybridization between probe A and probe B occurs with the formation of the C-Ag + -C complex in the presence of Ag + ions, leading to obvious fluorescence quenching in comparison to the system without AuNP enhancement. The assay can be used to identify nanomolar levels of Ag + within 6 min at room temperature, and has extremely high specificity for Ag + , even in the presence of higher concentrations of interfering metal ions. Furthermore, the sensor was successfully applied to the detection of Ag + ions in environmental water samples and showed excellent selectivity and high sensitivity, implying its promising application in the future. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Selective recognition of Pr3+ based on fluorescence enhancement sensor

    International Nuclear Information System (INIS)

    Ganjali, M.R.; Hosseini, M.; Ghafarloo, A.; Khoobi, M.; Faridbod, F.; Shafiee, A.; Norouzi, P.

    2013-01-01

    (E)-2-(1-(4-hydroxy-2-oxo-2H-chromen-3-yl)ethylidene) hydrazinecarbothioamide (L) has been used to detect trace amounts of praseodymium ion in acetonitrile–water solution (MeCN/H 2 O) by fluorescence spectroscopy. The fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to Pr 3+ ions in MeCN/H 2 O (9/1:v/v) solution. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Pr 3+ , which has been utilized as the basis for selective detection of Pr 3+ . The sensor can be applied to the quantification of praseodymium ion with a linear range of 1.6 × 10 −7 to 1.0 × 10 −5 M. The limit of detection was 8.3 × 10 −8 M. The sensor exhibits high selectivity toward praseodymium ions in comparison with common metal ions. The proposed fluorescent sensor was successfully used for determination of Pr 3+ in water samples. - Highlights: • A new fluorescent sensor is introduced as a selective probe for Pr 3+ detection. • Fluorescent intensity of the chemical probe enhances upon binding to Pr 3+ ion. • The sensor can be used for Pr 3+ determination in the range of 1.6 × 10 −7 –1.0 × 10 −5 M

  18. A facile fluorescent sensor based on silicon nanowires for dithionite

    Science.gov (United States)

    Cao, Xingxing; Mu, Lixuan; Chen, Min; She, Guangwei

    2018-05-01

    A facile and novel fluorescent sensor for dithionite has been constructed by simultaneously immobilizing dansyl group (fluorescence molecule) and dabsyl group (quencher and recognizing group) on the silicon nanowires (SiNWs) and SiNW arrays surface. This sensor for dithionite exhibited high selectivity and a good relationship of linearity between fluorescence intensities and dithionite concentrations from 0.1 to 1 mM. This approach is straightforward and does not require complicated synthesis, which can be extended to develop other sensors with similar rationale.

  19. A multifunctional molecularly imprinted polymer-based biosensor for direct detection of doxycycline in food samples

    DEFF Research Database (Denmark)

    Ashley, Jon; Feng, Xiaotong; Sun, Yi

    2018-01-01

    In this study, we developed a new type of multifunctional molecularly imprinted polymer (MIP) composite as an all-in-one biosensor for the low-cost, rapid and sensitive detection of doxycycline in pig plasma. The MIP composite consisted of a magnetic core for ease of manipulation, and a shell...... of fluorescent MIPs for selective recognition of doxycycline. By simply incorporating a small amount of fluorescent monomer (fluorescein-Oacrylate), the fluorescent MIP layer was successfully grafted onto the magnetic core via a surface imprinting technique. The resultant MIP composites showed significant....... The multifunctional MIP composites were used to directly extract doxycycline from spiked pig plasma samples and quantify the antibiotics based on the quenched fluorescence signals. Recoveries of doxycycline were found in the range of 88–107%....

  20. Fluorescent probe based on heteroatom containing styrylcyanine: pH-sensitive properties and bioimaging in vivo

    International Nuclear Information System (INIS)

    Yang, Xiaodong; Gao, Ya; Huang, Zhibing; Chen, Xiaohui; Ke, Zhiyong; Zhao, Peiliang; Yan, Yichen; Liu, Ruiyuan; Qu, Jinqing

    2015-01-01

    A novel fluorescent probe based on heteroatom containing styrylcyanine is synthesized. The fluorescence of probe is bright green in basic and neutral media but dark orange in strong acidic environments, which could be reversibly switched. Such behavior enables it to work as a fluorescent pH sensor in the solution state and a chemosensor for detecting acidic and basic volatile organic compounds. Analyses by NMR spectroscopy confirm that the protonation or deprotonation of pyridinyl moiety is responsible for the sensing process. In addition, the fluorescent microscopic images of probe in live cells and zebrafish are achieved successfully, suggesting that the probe has good cell membrane permeability and low cytotoxicity. - Graphical abstract: A novel styrylcyanine-based fluorescent pH probe was designed and synthesized, the fluorescence of which is bright green in basic and neutral media but dark orange in strong acidic environments. Such behavior enables it to work as a fluorescent pH sensor in solution states, and a chemosensor for detecting volatile organic compounds with high acidity and basicity in solid state. In addition, it can be used for fluorescent imaging in living cell and living organism. - Highlights: • Bright green fluorescence was observed in basic and neutral media. • Dark orange fluorescence was found in strong acidic environments. • Volatile organic compounds with high acidity and basicity could be detected. • Bioimaging in living cell and living organism was achieved successfully

  1. ALA-based fluorescent diagnosis of malignant oral lesions in the presence of bacterial porphyrin formation

    Science.gov (United States)

    Schleier, P.; Berndt, A.; Zinner, K.; Zenk, W.; Dietel, W.; Pfister, W.

    2006-02-01

    The aminolevulinic acid (5-ALA) -based fluorescence diagnosis has been found to be promising for an early detection and demarcation of superficial oral squamous cell carcinomas (OSCC). This method has previously demonstrated high sensitivity, however this clinical trial showed a specificity of approximately 62 %. This specificity was mainly restricted by tumor detection in the oral cavity in the presence of bacteria. After topical ALA application in the mouth of patients with previously diagnosed OSSC, red fluorescent areas were observed which did not correlate to confirm histological findings. Swabs and plaque samples were taken from 44 patients and cultivated microbiologically. Fluorescence was investigated (OMA-system) from 32 different bacteria strains found naturally in the oral cavity. After ALA incubation, 30 of 32 strains were found to synthesize fluorescent porphyrins, mainly Protoporphyrin IX. Also multiple fluorescent spectra were obtained having peak wavelengths of 636 nm and around 618 nm - 620 nm indicating synthesis of different porphyrins, such as the lipophylic Protoporphyrin IX (PpIX) and hydrophylic porphyrins (water soluble porphyrins, wsp). Of the 32 fluorescent bacterial strains, 18 produced wsp, often in combination with PpIX, and 5 produced solely wsp. These results clarify that ALA-based fluorescence diagnosis without consideration or suppression of bacteria fluorescence may lead to false-positive findings. It is necessary to suppress bacteria fluorescence with suitable antiseptics before starting the procedure. In this study, when specific antiseptic pre-treatment was performed bacterial associated fluorescence was significantly reduced.

  2. Gas Sensors Based on Molecular Imprinting Technology.

    Science.gov (United States)

    Zhang, Yumin; Zhang, Jin; Liu, Qingju

    2017-07-04

    Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size and functional groups. MIT has been successfully applied to analyze; separate and detect macromolecular organic compounds. Furthermore; it has been increasingly applied in assays of biological macromolecules. Owing to its unique features of structure specificity; predictability; recognition and universal application; there has been exploration of the possible application of MIPs in the field of highly selective gas sensors. In this present study; we outline the recent advances in gas sensors based on MIT; classify and introduce the existing molecularly imprinted gas sensors; summarize their advantages and disadvantages; and analyze further research directions.

  3. Molecular Level Understanding of Sodium Dodecyl Sulfate (SDS) Induced Sol-Gel Transition of Pluronic F127 Using Fisetin as a Fluorescent Molecular Probe.

    Science.gov (United States)

    Mishra, Jhili; Swain, Jitendriya; Mishra, Ashok Kumar

    2018-01-11

    The thermoreversible sol-gel transition of pluronic F127 is markedly altered even with addition of submicellar concentration of sodium dodecyl sulfate (SDS) surfactant. Multiple fluorescence parameters like fluorescence intensity, fluorescence anisotropy and fluorescence lifetime of both the prototropic forms (anion (A - *) and phototautomer FT*) of the photoprototropic fluorescent probe fisetin has been efficiently used to understand the molecular level properties like polarity and microviscosity of the PF127-SDS system as a function of temperature. The SDS-induced increase in the interfacial hydrophobicity level is seen to affect the sol-gel phase transition of PF127 (21-18 °C). The E T (30) polarity parameter value of anionic emission of fisetin suggests that there is a considerable decrease in the polarity of the PF127 medium with increase in temperature and with the addition of SDS. The microviscosity progressively increases from ∼5 mPa s (sol state, 10 °C) to ∼22.01 mPa s (gel state 35 °C) in aqueous solution of PF127. The variation in microviscosity with addition of SDS in PF127-SDS mixed system is significant in sol phase whereas in gel phase this variation is significantly less. Temperature dependent fluorescence lifetime of FT* indicates that there is heterogeneity in distribution of fisetin molecules at different domains of PF127. This work also show-cases the sensitivity of fisetin toward change in polarity and change in sol-gel transition temperature of copolymer PF127 with variation in temperature (both forward and reverse directions) and SDS.

  4. A coumarin-based colorimetric fluorescent probe for hydrogen sulfide

    Indian Academy of Sciences (India)

    with nitric oxide (NO) and carbon monoxide (CO), which mediate ... esterification, no emission of the fluorophore would be found due to ... Fluorescence emission spectra were obtained ... of excessive organic solvent might restrict the practical.

  5. Enhanced fluorescence of tetrasulfonated zinc phthalocyanine by graphene quantum dots and its application in molecular sensing/imaging.

    Science.gov (United States)

    Wang, Jian; Zhang, Yanjun; Ye, Jiqing; Jiang, Zhou

    2017-06-01

    When excited at 435 nm, tetra-sulfonate zinc phthalocyanine (ZnPcS 4 ) emitted dual fluorescence at 495 and 702 nm. The abnormal fluorescence at 495 nm was experimentally studied and analyzed in detail for the first time. The abnormal fluorescence at 495 nm was deduced to originate from triplet-triplet (T-T) energy transfer of excited phthalocyanine ( 3 *ZnPcS 4 ). Furthermore, graphene quantum dots (GQDs) enhanced the 495 nm fluorescence quantum yield (Q) of ZnPcS 4 . The fluorescence properties of ZnPcS 4 -GQDs conjugate were retained in a cellular environment. Based on the fluorescence of ZnPcS 4 -GQDs conjugate, we designed and prepared an Apt29/thrombin/Apt15 sandwich thrombin sensor with high specificity and affinity. This cost-saving, simple operational sensing strategy can be extended to use in sensing/imaging of other biomolecules. Copyright © 2016 John Wiley & Sons, Ltd.

  6. A fluorescent molecular sensor for pH windows in traditional and polymeric biocompatible micelles: comicellization of anionic species to shift and reshape the ON window.

    Science.gov (United States)

    Cavallaro, Gennara; Giammona, Gaetano; Pasotti, Luca; Pallavicini, Piersandro

    2011-09-12

    A new approach is presented to obtain fluorescent sensors for pH windows that work in water and under biomimetic conditions. A single molecule that features all-covalently linked components is used, thus making it capable of working as a fluorescent sensor with an OFF/ON/OFF response to pH value. The components are a tertiary amine, a pyridine, and a fluorophore (pyrene). The forms with both protonated bases or both neutral bases quench the pyrene fluorescence, whereas the form with the neutral pyridine and protonated amine groups is fluorescent. The molecular sensor is also equipped with a long alkyl chain to make it highly hydrophobic in all its protonated and unprotonated forms, that is, either when neutral or charged. Accordingly, it can be confined at any pH value either in traditional (i.e., low-molecular-weight) nonionic surfactant micelles or inside polymeric, biocompatible micellar containers. Relevant for future applications in vivo, thanks to its strong hydrophobicity, no leakage of the molecular sensor is observed from the polymeric biocompatible micelles. Due to the proximity of the pyridine and amine functions in the molecular structure and the poor hydration inside the micelles, the observed pK(a) values are low so that the ON window is positioned at very low pH values. However, the window can be shifted to biologically relevant values by comicellization of anionic species. In particular, in the micelles of the nonionic surfactant TritonX-100, a shift of the ON window to pH 4-6 is obtained by addition of the anionic sodium dodecyl sulphate surfactant, whose negative charge promotes the stability of the protonated forms of the pyridine and amine fragments. In the case of the polymeric micelles, we introduce the use of the amphiphilic polystyrene sulfonate anionic polyelectrolyte, the comicellization of which induces a shift and sharpening of the ON window that is centered at pH 4. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Identification of adiponectin receptor agonist utilizing a fluorescence polarization based high throughput assay.

    Directory of Open Access Journals (Sweden)

    Yiyi Sun

    Full Text Available Adiponectin, the adipose-derived hormone, plays an important role in the suppression of metabolic disorders that can result in type 2 diabetes, obesity, and atherosclerosis. It has been shown that up-regulation of adiponectin or adiponectin receptor has a number of therapeutic benefits. Given that it is hard to convert the full size adiponectin protein into a viable drug, adiponectin receptor agonists could be designed or identified using high-throughput screening. Here, we report on the development of a two-step screening process to identify adiponectin agonists. First step, we developed a high throughput screening assay based on fluorescence polarization to identify adiponectin ligands. The fluorescence polarization assay reported here could be adapted to screening against larger small molecular compound libraries. A natural product library containing 10,000 compounds was screened and 9 hits were selected for validation. These compounds have been taken for the second-step in vitro tests to confirm their agonistic activity. The most active adiponectin receptor 1 agonists are matairesinol, arctiin, (--arctigenin and gramine. The most active adiponectin receptor 2 agonists are parthenolide, taxifoliol, deoxyschizandrin, and syringin. These compounds may be useful drug candidates for hypoadiponectin related diseases.

  8. Binding analysis for interaction of diacetylcurcumin with β-casein nanoparticles by using fluorescence spectroscopy and molecular docking calculations

    Science.gov (United States)

    Mehranfar, Fahimeh; Bordbar, Abdol-Khalegh; Fani, Najme; Keyhanfar, Mehrnaz

    2013-11-01

    The interaction of diacetylcurcumin (DAC), as a novel synthetic derivative of curcumin, with bovine β-casein (an abundant milk protein that is highly amphiphilic and self assembles into stable micellar nanoparticles in aqueous solution) was investigated using fluorescence quenching experiments, Forster energy transfer measurements and molecular docking calculations. The fluorescence quenching measurements revealed the presence of a single binding site on β-casein for DAC with the binding constant value equals to (4.40 ± 0.03) × 104 M-1. Forster energy transfer measurements suggested that the distance between bound DAC and Trp143 residue is higher than the respective critical distance, hence, the static quenching is more likely responsible for fluorescence quenching other than the mechanism of non-radiative energy transfer. Our results from molecular docking calculations indicated that binding of DAC to β-casein predominantly occurred through hydrophobic contacts in the hydrophobic core of protein. Additionally, in vitro investigation of the cytotoxicity of free DAC and DAC-β-casein complex in human breast cancer cell line MCF7 revealed the higher cytotoxic effect of DAC-β-casein complex.

  9. Crystallography and Molecular Arrangement of Polymorphic Monolayer J-Aggregates of a Cyanine Dye: Multiangle Polarized Light Fluorescence Optical Microscopy Study.

    Science.gov (United States)

    Prokhorov, Valery V; Pozin, Sergey I; Perelygina, Olga M; Mal'tsev, Eugene I

    2018-04-24

    The molecular orientation in monolayer J-aggregates of 3,3-di(γ-sulfopropyl)-5,5-dichlorotiamonomethinecyanine dye has been precisely estimated using improved linear polarization measurements in the fluorescence microscope in which a multiangle set of polarization data is obtained using sample rotation. The estimated molecular orientation supplemented with the previously established crystallographic constraints based on the analysis of the well-developed two-dimensional J-aggregate shapes unambiguously indicate the staircase type of molecular arrangement for striplike J-aggregates with the staircases oriented along strips. The molecular transition dipoles are inclined at an angle of ∼25° to the strip direction, whereas the characteristic strip vertex angle ∼45° is formed by the [100] and [1-10] directions of the monoclinic unit cell. Measurements of the geometry of partially unwound tubes and their polarization properties support the model of tube formation by close-packed helical winding of flexible monolayer strips. In the tubes, the long molecular axes are oriented at a small angle in the range of 5-15° to the normal to the tube axis providing low bending energy. At a nanoscale, high-resolution atomic force microscopy imaging of J-aggregate monolayers reveals a complex quasi-one-dimensional organization.

  10. Excitation and deexcitation of N2 molecular levels. Induced fluorescence by electrons and laser

    International Nuclear Information System (INIS)

    Perez Fernandez-Mayoralas, A.

    1989-01-01

    The electron impact excitation followed by fluorescence induced by N 2 -laser absorption was used to study the lifetime of the lowest vibrational level of the B 3 π g electronic state of N 2 . The experimental result of this work is 13 + 1 μs. To measure the lifetime of B 3 π g (v=2,3,5,6,7,8) levels the delayed coincidence method by electron impact was use. The lifetime values were compared with recent experimental and theoretical results. The relative intensi-ties of 3 π g --- A 3 Σ Ω + system bands, in the range (6540-10500 A o ) was measured using a hollow cathode lamp as spectral source. The relative transition moments and its dependence versus the r-centroid was obtained. Total cross sections for electron scattering by N molecules in the range 600 - 5000 eV have been obtained from measurements of the attenuation of a linear electron beam. The results have been compared with available experimental cross sections and with theoretical calculations based on the first Born approximation. (Author)

  11. Molecular phylogeny of Ranunculaceae based on internal ...

    African Journals Online (AJOL)

    The botanical family Ranunculaceae contains important medicinal plants. To obtain new evolutionary evidence regarding the systematic classification of Ranunculaceae plants, we used molecular phylogenies to test relationships based on the internal transcribed spacer region. The results of phylogenetic analysis of 92 ...

  12. Fluorescent sensor systems based on nanostructured polymeric membranes for selective recognition of Aflatoxin B1.

    Science.gov (United States)

    Sergeyeva, Tetyana; Yarynka, Daria; Piletska, Elena; Lynnik, Rostyslav; Zaporozhets, Olga; Brovko, Oleksandr; Piletsky, Sergey; El'skaya, Anna

    2017-12-01

    Nanostructured polymeric membranes for selective recognition of aflatoxin B1 were synthesized in situ and used as highly sensitive recognition elements in the developed fluorescent sensor. Artificial binding sites capable of selective recognition of aflatoxin B1 were formed in the structure of the polymeric membranes using the method of molecular imprinting. A composition of molecularly imprinted polymer (MIP) membranes was optimized using the method of computational modeling. The MIP membranes were synthesized using the non-toxic close structural analogue of aflatoxin B1, ethyl-2-oxocyclopentanecarboxylate as a dummy template. The MIP membranes with the optimized composition demonstrated extremely high selectivity towards aflatoxin B1 (AFB1). Negligible binding of close structural analogues of AFB1 - aflatoxins B2 (AFB2), aflatoxin G2 (AFG2), and ochratoxin A (OTA) was demonstrated. Binding of AFB1 by the MIP membranes was investigated as a function of both type and concentration of the functional monomer in the initial monomer composition used for the membranes' synthesis, as well as sample composition. The conditions of the solid-phase extraction of the mycotoxin using the MIP membrane as a stationary phase (pH, ionic strength, buffer concentration, volume of the solution, ratio between water and organic solvent, filtration rate) were optimized. The fluorescent sensor system based on the optimized MIP membranes provided a possibility of AFB1 detection within the range 14-500ngmL -1 demonstrating detection limit (3Ϭ) of 14ngmL -1 . The developed technique was successfully applied for the analysis of model solutions and waste waters from bread-making plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Synthesis and Application of Polymeric Fluorescent Compounds Based on Coumarin

    Directory of Open Access Journals (Sweden)

    Guojun Liu

    2015-06-01

    Full Text Available In this work, a multifunctional yellowing inhibitor was synthesized by the Pechmann method. In order to obtain the target compound, 7-hydroxy-4-methyl coumarin was prepared by using the raw materials of resorcinol and ethyl acetoacetate, with toluene-p-sulfonic acid as the catalyst. New polymeric fluorescent compounds were synthesized by connecting the 7-hydroxy-4-methyl coumarin, the hindered amine light stabilizer 4-amion-2,2,6,6-tetramentylniperidine, and a series of polyethylene glycol segments into the same molecule with cyanuric chloride as a bridge. The structures of the synthesized molecules were confirmed by FT-IR, 1H NMR, and elemental analysis. The luminescent properties of the fluorescent compounds were studied by UV-vis spectroscopy and fluorescence spectroscopy. The integration effect between the fluorescent compounds and paper was tested by a scanning electron microscope. The light stability effect on the paper sheet was tested using an ultraviolet aging apparatus. The results indicate that the polymeric fluorescent compounds had a positive effect on the light stability of the high-yield pulp.

  14. Efficient fluorescent deep-blue and hybrid white emitting devices based on carbazole/benzimidazole compound

    KAUST Repository

    Yang, Xiaohui; Zheng, Shijun; Bottger, Rebecca; Chae, HyunSik; Tanaka, Takeshi; Li, Sheng; Mochizuki, Amane; Jabbour, Ghassan E.

    2011-01-01

    We report the synthesis, photophysics, and electrochemical characterization of carbazole/benzimidazole-based compound (Cz-2pbb) and efficient fluorescent deep-blue light emitting devices based on Cz-2pbb with the peak external quantum efficiency

  15. Graphene-based nanoprobes for molecular diagnostics.

    Science.gov (United States)

    Chen, Shixing; Li, Fuwu; Fan, Chunhai; Song, Shiping

    2015-10-07

    In recent years, graphene has received widespread attention owing to its extraordinary electrical, chemical, optical, mechanical and structural properties. Lately, considerable interest has been focused on exploring the potential applications of graphene in life sciences, particularly in disease-related molecular diagnostics. In particular, the coupling of functional molecules with graphene as a nanoprobe offers an excellent platform to realize the detection of biomarkers, such as nucleic acids, proteins and other bioactive molecules, with high performance. This article reviews emerging graphene-based nanoprobes in electrical, optical and other assay methods and their application in various strategies of molecular diagnostics. In particular, this review focuses on the construction of graphene-based nanoprobes and their special advantages for the detection of various bioactive molecules. Properties of graphene-based materials and their functionalization are also comprehensively discussed in view of the development of nanoprobes. Finally, future challenges and perspectives of graphene-based nanoprobes are discussed.

  16. Orthonormal Wavelet Bases for Quantum Molecular Dynamics

    International Nuclear Information System (INIS)

    Tymczak, C.; Wang, X.

    1997-01-01

    We report on the use of compactly supported, orthonormal wavelet bases for quantum molecular-dynamics (Car-Parrinello) algorithms. A wavelet selection scheme is developed and tested for prototypical problems, such as the three-dimensional harmonic oscillator, the hydrogen atom, and the local density approximation to atomic and molecular systems. Our method shows systematic convergence with increased grid size, along with improvement on compression rates, thereby yielding an optimal grid for self-consistent electronic structure calculations. copyright 1997 The American Physical Society

  17. Molecular imaging of atherosclerosis in mice with MRI and near-infrared fluorescence imaging

    International Nuclear Information System (INIS)

    Lu Tong; Wen Song; Zhou Guanhui; Ju Shenghong; Teng Gaojun

    2012-01-01

    Objective: To explore the feasibility of detecting atherosclerotic plaques with 7.0 T MRI and near-infrared fluorescence imaging (NIRF) using molecular imaging probes. Methods: Atherosclerotic plaques were established in male atherosclerotic apolipoprotein E knockout (ApoE-/-) mice fed with high-cholesterol diet for 20 weeks. Wild-type C57BL/6 mice were used as negative controls. 7.0 T MRI was performed before and 36 h after intravenously administration of ultrasmall superparamagnetic particle of iron oxide (USPIO). NIR 797 was conjugated with anti-mouse-oxidized modified low density lipoprotein (oxLDL) antibodies to construct an anti-oxLDL-Ab-NIR 797 probe while non-specific IgG-NIR 797 and PBS used as controls. NIRF was performed 24 h after tail vein injection of the probe. Independent sample t-test and one-way analysis of variance were used to analyze the data by SPSS 17.0. Results: In APOE-/-mice, in vivo 36 h post-USPIO T 2 WI images revealed strong focal signal loss in the abdominal aorta than that of pre-USPIO, with relative signal intensity 0.70 ± 0.04 and 1.28 ± 0.06, respectively (t=3.376, P<0.05). The percent of signal reduced was (-56.58 ± 4.25)%. The Prussian blue staining confirmed the depositions of iron particles in the plaque lesions. Significant fluorochrome accumulation in atherosclerotic plaques was demonstrated in aortic root, aortic arch and the starting of descending aorta 24 h after injection of the anti-oxLDL-Ab-NIR 797 probe. Minimal antibody uptake was observed in normal vessels from wild-type mice receiving the anti-oxLDL-Ab-NIR 797 (SNR: 2.29 ± 1.11) and in atherosclerotic vessels from ApoE-/- mice receiving the non-specific IgG-NIR 797 (19.58 ±3.06) or PBS (4.19 ±0.82), which was significantly different from the uptake of anti-oxLDL-Ab-NIR 797 group (42.51 ±5.24, F=25.104, P<0.05). Comparison between oil red O staining and NIRF 24 h after injection of NIR 797 labeled oxLDL-antibody revealed a significant correlation (r=0.738, P

  18. Saturated virtual fluorescence emission difference microscopy based on detector array

    Science.gov (United States)

    Liu, Shaocong; Sun, Shiyi; Kuang, Cuifang; Ge, Baoliang; Wang, Wensheng; Liu, Xu

    2017-07-01

    Virtual fluorescence emission difference microscopy (vFED) has been proposed recently to enhance the lateral resolution of confocal microscopy with a detector array, implemented by scanning a doughnut-shaped pattern. Theoretically, the resolution can be enhanced by around 1.3-fold compared with that in confocal microscopy. For further improvement of the resolving ability of vFED, a novel method is presented utilizing fluorescence saturation for super-resolution imaging, which we called saturated virtual fluorescence emission difference microscopy (svFED). With a point detector array, matched solid and hollow point spread functions (PSF) can be obtained by photon reassignment, and the difference results between them can be used to boost the transverse resolution. Results show that the diffraction barrier can be surpassed by at least 34% compared with that in vFED and the resolution is around 2-fold higher than that in confocal microscopy.

  19. A new pyrazoline-based fluorescent sensor for Al3+ in aqueous solution.

    Science.gov (United States)

    Hu, Shengli; Song, Jingjing; Wu, Gongying; Cheng, Cuixia; Gao, Qing

    2015-02-05

    A new pyrazoline-based fluorescent sensor was synthesized and the structure was confirmed by single crystal X-ray diffraction. The sensor responds to Al(3+) with high selectivity among a series of cations in aqueous methanol. This sensor forms a 1:1 complex with Al(3+) and displays fluorescent quenching. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. A nanoplasmonic switch based on molecular machines

    KAUST Repository

    Zheng, Yue Bing

    2009-06-01

    We aim to develop a molecular-machine-driven nanoplasmonic switch for its use in future nanophotonic integrated circuits (ICs) that have applications in optical communication, information processing, biological and chemical sensing. Experimental data show that an Au nanodisk array, coated with rotaxane molecular machines, switches its localized surface plasmon resonances (LSPR) reversibly when it is exposed to chemical oxidants and reductants. Conversely, bare Au nanodisks and disks coated with mechanically inert control compounds, do not display the same switching behavior. Along with calculations based on time-dependent density functional theory (TDDFT), these observations suggest that the nanoscale movements within surface-bound "molecular machines" can be used as the active components in plasmonic devices. ©2009 IEEE.

  1. Fluorescence-based biosensors from concepts to applications

    CERN Document Server

    Morris, May C

    2013-01-01

    One of the major challenges of modern biology and medicine consists in finding means to visualize biomolecules in their natural environment with the greatest level of accuracy, so as to gain insight into their properties and behaviour in a physiological and pathological setting. This has been achieved thanks to the design of novel imaging agents, in particular to fluorescent biosensors. Fluorescence Biosensors comprise a large set of tools which are useful for fundamental purposes as well as for applications in biomedicine, drug discovery and biotechnology. These tools have been designed a

  2. Indirect Fluorescent Antibody Technique based Prevalence of Surra in Equines

    Directory of Open Access Journals (Sweden)

    Ahsan Nadeem, Asim Aslam*, Zafar Iqbal Chaudhary, Kamran Ashraf1, Khalid Saeed1, Nisar Ahmad1, Ishtiaq Ahmed and Habib ur Rehman2

    2011-04-01

    Full Text Available This project was carried out to find the prevalence of trypanosomiasis in equine in District Gujranwala by using indirect fluorescent antibody technique and thin smear method. Blood samples were collected from a total of 200 horses and donkeys of different ages and either sex. Duplicate thin blood smears were prepared from each sample and remaining blood samples were centrifuged to separate the serum. Smears from each animal were processed for giemsa staining and indirect fluorescent antibody test (IFAT. Giemsa stained smears revealed Trypanosome infection in 4/200 (2.0% samples and IFAT in 12/200 (6.0% animals.

  3. Balanced cross-rate model for saturated molecular fluorescence in flames using a nanosecond pulse length laser

    International Nuclear Information System (INIS)

    Lucht, R.P.; Sweeney, D.W.; Laurendeau, N.M.

    1980-01-01

    The balanced cross-rate model is proposed to analyze laser-induced molecular fluorescence signals when the laser pulse length is of the order of nanoseconds. Nanosecond pulse length lasers. specifically Q-switched Nd:YAG-pumped dye lasers, are attractive for saturated molecular fluorescence spectroscopy because of their high peak power and because of their short pulse length minimizes the risk of laser-induced chemistry. In the balanced cross-rate model, single upper and lower rotational levels are assumed to be directly coupled by the laser radiation. Because the laser-induced processes which couple these levels are so fast at saturation intensities, a steady state is established between the two levels within picoseconds. Provided that the total population of the two laser-coupled rotational levels is constant during the laser pulse, the total molecular population can be calculated from the observed upper rotational level population using a two-level saturation model and Boltzmann statistics. Numerical simulation of the laser excitation dynamics of OH in an atmospheric pressure H 2 /O 2 /N 2 flame indicates that the balanced cross-rate model will give accurate results provided that the rotational relaxation rates in the upper and lower sets of rotational levels are approximately equal

  4. Investigation of the interaction between isomeric derivatives and human serum albumin by fluorescence spectroscopy and molecular modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruiyong, E-mail: wangry@zzu.edu.cn; Dou, Huanjing; Yin, Yujing; Xie, Yuanzhe; Sun, Li; Liu, Chunmei; Dong, Jingjing; Huang, Gang; Zhu, Yanyan; Song, Chuanjun, E-mail: chjsong@zzu.edu.cn; Chang, Junbiao, E-mail: changjunbiao@zzu.edu.cn

    2014-10-15

    In this paper, we have synthesized 9H-pyrrolo[1,2-a]indol-9-ones and the isomeric indeno[2,1-b]pyrrol-8-ones. The interactions of human serum albumin with series of isomeric derivatives have been studied by spectrophotometric methods. Results show the intrinsic fluorescence is quenched by the derivatives with a static quenching procedure. The thermodynamics parameters indicate that van der Waals forces and hydrogen bonds play a major role in the interactions. The results of synchronous fluorescence spectra demonstrate that the microenvironments of Trp residue of human serum albumin are disturbed by most derivatives. Thermodynamic results showed that the 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers and bind to human serum albumin with the higher affinity than isomeric indeno[2,1-b]pyrrol-8-ones. The influence of molecular structure on the binding aspects has been investigated. - Highlights: • The interactions between isomeric derivatives and HSA have been investigated. • Results reveal that 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers for HSA. • Hydrogen bonds and van der Waals forces play major role in the binding process. • The influence of molecular structure on the binding aspects has been investigated. • The binding study was also modeled by molecular docking.

  5. Investigation of the interaction between isomeric derivatives and human serum albumin by fluorescence spectroscopy and molecular modeling

    International Nuclear Information System (INIS)

    Wang, Ruiyong; Dou, Huanjing; Yin, Yujing; Xie, Yuanzhe; Sun, Li; Liu, Chunmei; Dong, Jingjing; Huang, Gang; Zhu, Yanyan; Song, Chuanjun; Chang, Junbiao

    2014-01-01

    In this paper, we have synthesized 9H-pyrrolo[1,2-a]indol-9-ones and the isomeric indeno[2,1-b]pyrrol-8-ones. The interactions of human serum albumin with series of isomeric derivatives have been studied by spectrophotometric methods. Results show the intrinsic fluorescence is quenched by the derivatives with a static quenching procedure. The thermodynamics parameters indicate that van der Waals forces and hydrogen bonds play a major role in the interactions. The results of synchronous fluorescence spectra demonstrate that the microenvironments of Trp residue of human serum albumin are disturbed by most derivatives. Thermodynamic results showed that the 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers and bind to human serum albumin with the higher affinity than isomeric indeno[2,1-b]pyrrol-8-ones. The influence of molecular structure on the binding aspects has been investigated. - Highlights: • The interactions between isomeric derivatives and HSA have been investigated. • Results reveal that 9H-pyrrolo[1,2-a]indol-9-ones are stronger quenchers for HSA. • Hydrogen bonds and van der Waals forces play major role in the binding process. • The influence of molecular structure on the binding aspects has been investigated. • The binding study was also modeled by molecular docking

  6. New insights into heat induced structural changes of pectin methylesterase on fluorescence spectroscopy and molecular modeling basis

    Science.gov (United States)

    Nistor, Oana Viorela; Stănciuc, Nicoleta; Aprodu, Iuliana; Botez, Elisabeta

    2014-07-01

    Heat-induced structural changes of Aspergillus oryzae pectin methylesterase (PME) were studied by means of fluorescence spectroscopy and molecular modeling, whereas the functional enzyme stability was monitored by inactivation studies. The fluorescence spectroscopy experiments were performed at two pH value (4.5 and 7.0). At both pH values, the phase diagrams were linear, indicating the presence of two molecular species induced by thermal treatment. A red shift of 7 nm was observed at neutral pH by increasing temperature up to 60 °C, followed by a blue shift of 4 nm at 70 °C, suggesting significant conformational rearrangements. The quenching experiments using acrylamide and iodide demonstrate a more flexible conformation of enzyme with increasing temperature, especially at neutral pH. The experimental results were complemented with atomic level observations on PME model behavior after performing molecular dynamics simulations at different temperatures. The inactivation kinetics of PME in buffer solutions was fitted using a first-order kinetics model, resulting in activation energy of 241.4 ± 7.51 kJ mol-1.

  7. A matter of collection and detection for intraoperative and noninvasive near-infrared fluorescence molecular imaging: To see or not to see?

    Science.gov (United States)

    Zhu, Banghe; Rasmussen, John C.; Sevick-Muraca, Eva M.

    2014-01-01

    Purpose: Although fluorescence molecular imaging is rapidly evolving as a new combinational drug/device technology platform for molecularly guided surgery and noninvasive imaging, there remains no performance standards for efficient translation of “first-in-humans” fluorescent imaging agents using these devices. Methods: The authors employed a stable, solid phantom designed to exaggerate the confounding effects of tissue light scattering and to mimic low concentrations (nM–pM) of near-infrared fluorescent dyes expected clinically for molecular imaging in order to evaluate and compare the commonly used charge coupled device (CCD) camera systems employed in preclinical studies and in human investigational studies. Results: The results show that intensified CCD systems offer greater contrast with larger signal-to-noise ratios in comparison to their unintensified CCD systems operated at clinically reasonable, subsecond acquisition times. Conclusions: Camera imaging performance could impact the success of future “first-in-humans” near-infrared fluorescence imaging agent studies. PMID:24506637

  8. A Starting Point for Fluorescence-Based Single-Molecule Measurements in Biomolecular Research

    Directory of Open Access Journals (Sweden)

    Alexander Gust

    2014-09-01

    Full Text Available Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.

  9. Study on serum fluorescence spectra based on wavelet transform

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-08

    Feb 8, 2010 ... Blood plays an important role in clinical diagnosis and treatment and as such, the analysis of blood spectrum will be of very important practical significance. Serum fluorescence emission intensity is closely related with the excitation wavelength; when the excitation wavelength is 230 nm, the blood.

  10. Study on serum fluorescence spectra based on wavelet transform ...

    African Journals Online (AJOL)

    Blood plays an important role in clinical diagnosis and treatment and as such, the analysis of blood spectrum will be of very important practical significance. Serum fluorescence emission intensity is closely related with the excitation wavelength; when the excitation wavelength is 230 nm, the blood lipid concentration and ...

  11. DNA origami-based standards for quantitative fluorescence microscopy.

    Science.gov (United States)

    Schmied, Jürgen J; Raab, Mario; Forthmann, Carsten; Pibiri, Enrico; Wünsch, Bettina; Dammeyer, Thorben; Tinnefeld, Philip

    2014-01-01

    Validating and testing a fluorescence microscope or a microscopy method requires defined samples that can be used as standards. DNA origami is a new tool that provides a framework to place defined numbers of small molecules such as fluorescent dyes or proteins in a programmed geometry with nanometer precision. The flexibility and versatility in the design of DNA origami microscopy standards makes them ideally suited for the broad variety of emerging super-resolution microscopy methods. As DNA origami structures are durable and portable, they can become a universally available specimen to check the everyday functionality of a microscope. The standards are immobilized on a glass slide, and they can be imaged without further preparation and can be stored for up to 6 months. We describe a detailed protocol for the design, production and use of DNA origami microscopy standards, and we introduce a DNA origami rectangle, bundles and a nanopillar as fluorescent nanoscopic rulers. The protocol provides procedures for the design and realization of fluorescent marks on DNA origami structures, their production and purification, quality control, handling, immobilization, measurement and data analysis. The procedure can be completed in 1-2 d.

  12. Ratiometric fluorescent nanosensor based on carbon dots for the detection of mercury ion

    Science.gov (United States)

    Ma, Yusha; Mei, Jing; Bai, Jianliang; Chen, Xu; Ren, Lili

    2018-05-01

    A novel ratiometric fluorescent nanosensor based on carbon dots has been synthesized via bonding rhodamine B hydrazide to the carbon dots surface by an amide reaction. The ratiometric fluorescent nanosensor showed only a single blue fluorescence emission around 450 nm. While, as mercury ion was added, due to the open-ring of rhodamine moiety bonded on the CDs surface, the orange emission of the open-ring rhodamine would increase obviously according to the concentration of mercury ion, resulting in the distinguishable dual emissions at 450 nm and 575 nm under a single 360 excitation wavelength. Meanwhile, the ratiometric fluorescent nanosensor based on carbon dots we prepared is more sensitive to qualitative and semi-quantitative detection of mercury ion in the range of 0–100 μM, because fluorescence changes gradually from blue to orange emission under 365 nm lamp with the increasing of mercury ion in the tested solution.

  13. A Thiazole Coumarin (TC) Turn-On Fluorescence Probe for AT-Base Pair Detection and Multipurpose Applications in Different Biological Systems

    Science.gov (United States)

    Narayanaswamy, Nagarjun; Kumar, Manoj; Das, Sadhan; Sharma, Rahul; Samanta, Pralok K.; Pati, Swapan K.; Dhar, Suman K.; Kundu, Tapas K.; Govindaraju, T.

    2014-01-01

    Sequence-specific recognition of DNA by small turn-on fluorescence probes is a promising tool for bioimaging, bioanalytical and biomedical applications. Here, the authors report a novel cell-permeable and red fluorescent hemicyanine-based thiazole coumarin (TC) probe for DNA recognition, nuclear staining and cell cycle analysis. TC exhibited strong fluorescence enhancement in the presence of DNA containing AT-base pairs, but did not fluoresce with GC sequences, single-stranded DNA, RNA and proteins. The fluorescence staining of HeLa S3 and HEK 293 cells by TC followed by DNase and RNase digestion studies depicted the selective staining of DNA in the nucleus over the cytoplasmic region. Fluorescence-activated cell sorting (FACS) analysis by flow cytometry demonstrated the potential application of TC in cell cycle analysis in HEK 293 cells. Metaphase chromosome and malaria parasite DNA imaging studies further confirmed the in vivo diagnostic and therapeutic applications of probe TC. Probe TC may find multiple applications in fluorescence spectroscopy, diagnostics, bioimaging and molecular and cell biology. PMID:25252596

  14. Detection of Naja atra Cardiotoxin Using Adenosine-Based Molecular Beacon.

    Science.gov (United States)

    Shi, Yi-Jun; Chen, Ying-Jung; Hu, Wan-Ping; Chang, Long-Sen

    2017-01-07

    This study presents an adenosine (A)-based molecular beacon (MB) for selective detection of Naja atra cardiotoxin (CTX) that functions by utilizing the competitive binding between CTX and the poly(A) stem of MB to coralyne. The 5'- and 3'-end of MB were labeled with a reporter fluorophore and a non-fluorescent quencher, respectively. Coralyne induced formation of the stem-loop MB structure through A₂-coralyne-A₂ coordination, causing fluorescence signal turn-off due to fluorescence resonance energy transfer between the fluorophore and quencher. CTX3 could bind to coralyne. Moreover, CTX3 alone induced the folding of MB structure and quenching of MB fluorescence. Unlike that of snake venom α-neurotoxins, the fluorescence signal of coralyne-MB complexes produced a bell-shaped concentration-dependent curve in the presence of CTX3 and CTX isotoxins; a turn-on fluorescence signal was noted when CTX concentration was ≤80 nM, while a turn-off fluorescence signal was noted with a further increase in toxin concentrations. The fluorescence signal of coralyne-MB complexes yielded a bell-shaped curve in response to varying concentrations of N. atra crude venom but not those of Bungarus multicinctus and Protobothrops mucrosquamatus venoms. Moreover, N. nigricollis venom also functioned as N. atra venom to yield a bell-shaped concentration-dependent curve of MB fluorescence signal, again supporting that the hairpin-shaped MB could detect crude venoms containing CTXs. Taken together, our data validate that a platform composed of coralyne-induced stem-loop MB structure selectively detects CTXs.

  15. Fast automatic segmentation of anatomical structures in x-ray computed tomography images to improve fluorescence molecular tomography reconstruction.

    Science.gov (United States)

    Freyer, Marcus; Ale, Angelique; Schulz, Ralf B; Zientkowska, Marta; Ntziachristos, Vasilis; Englmeier, Karl-Hans

    2010-01-01

    The recent development of hybrid imaging scanners that integrate fluorescence molecular tomography (FMT) and x-ray computed tomography (XCT) allows the utilization of x-ray information as image priors for improving optical tomography reconstruction. To fully capitalize on this capacity, we consider a framework for the automatic and fast detection of different anatomic structures in murine XCT images. To accurately differentiate between different structures such as bone, lung, and heart, a combination of image processing steps including thresholding, seed growing, and signal detection are found to offer optimal segmentation performance. The algorithm and its utilization in an inverse FMT scheme that uses priors is demonstrated on mouse images.

  16. Graphene oxide based fluorescence resonance energy transfer and loop-mediated isothermal amplification for white spot syndrome virus detection.

    Science.gov (United States)

    Waiwijit, U; Phokaratkul, D; Kampeera, J; Lomas, T; Wisitsoraat, A; Kiatpathomchai, W; Tuantranont, A

    2015-10-20

    Graphene oxide (GO) is attractived for biological or medical applications due to its unique electrical, physical, optical and biological properties. In particular, GO can adsorb DNA via π-π stacking or non-covalent interactions, leading to fluorescence quenching phenomenon applicable for bio-molecular detection. In this work, a new method for white spot syndrome virus (WSSV)-DNA detection is developed based on loop-mediated isothermal amplification (LAMP) combined with fluorescence resonance energy transfer (FRET) between GO and fluorescein isothiocyanate-labeled probe (FITC-probe). The fluorescence quenching efficiency of FITC-probe was found to increase with increasing GO concentration and reached 98.7% at a GO concentration of 50 μg/ml. The fluorescence intensity of FITC-probe was recovered after hybridization with WSSV LAMP product with an optimal hybridization time of 10 min and increased accordingly with increasing amount of LAMP products. The detection limit was estimated to be as low as 10 copies of WSSV plasmid DNA or 0.6 fg of the total DNA extracted from shrimp infected with WSSV. In addition, no cross reaction was observed with other common shrimp viral pathogens. Therefore, the GO-FRET-LAMP technique is promising for fast, sensitive and specific detection of DNAs. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Gold and silver nanoparticles based superquenching of fluorescence: A review

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Debanjana; Chattopadhyay, Nitin, E-mail: nitin.chattopadhyay@yahoo.com

    2015-04-15

    The short review highlights the recent advances on the gold and silver nanoparticles induced efficient quenching of fluorescence from various fluorophores looking at their promising use as optical rulers and chemo-/bio- sensors. The fluorescence quenching often leads to the increase in the Stern–Volmer constant (K{sub SV}~10{sup 7}–10{sup 10} mol{sup −1} dm{sup 3}) several orders of magnitude higher than the values observed for the normal photochemical quenching processes (~10{sup 2} mol{sup −1} dm{sup 3}). This amplified quenching has been termed as “super-quenching” or “hyper-quenching”. Energy transfer (ET) is established from the donor to the metal nanoparticles rationalizing these fast quenching processes. Considering the distance dependence of the ET process, Förster resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) are ascribed to take place. These sensitive distance dependent phenomena serve as the spectroscopic ruler to measure the intra- or intermolecular distances between the interacting partners. In this account focus has been laid on the size dependent energy transfer and super- and hyper- quenching of the fluorescence of the donor moieties by the nanometals and their probable applications in sensing. Rationalization has been made for the nanoparticle induced huge enhancement in the quenching efficiency. The impact of this review lies in the possible application of these amplified quenching processes in designing high sensitive chemical and biological sensors. - Highlights: • Super efficient quenching of fluorescence of probes by gold and silver nanoparticles is highlighted. • The amplified fluorescence quenching of dyes and polymers is rationalized. • Energy transfer is assigned to be responsible for the efficient quenching process. • Amplified quenching has its potential use in designing sensitive chemical/biological sensors.

  18. Gold and silver nanoparticles based superquenching of fluorescence: A review

    International Nuclear Information System (INIS)

    Ghosh, Debanjana; Chattopadhyay, Nitin

    2015-01-01

    The short review highlights the recent advances on the gold and silver nanoparticles induced efficient quenching of fluorescence from various fluorophores looking at their promising use as optical rulers and chemo-/bio- sensors. The fluorescence quenching often leads to the increase in the Stern–Volmer constant (K SV ~10 7 –10 10 mol −1 dm 3 ) several orders of magnitude higher than the values observed for the normal photochemical quenching processes (~10 2 mol −1 dm 3 ). This amplified quenching has been termed as “super-quenching” or “hyper-quenching”. Energy transfer (ET) is established from the donor to the metal nanoparticles rationalizing these fast quenching processes. Considering the distance dependence of the ET process, Förster resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) are ascribed to take place. These sensitive distance dependent phenomena serve as the spectroscopic ruler to measure the intra- or intermolecular distances between the interacting partners. In this account focus has been laid on the size dependent energy transfer and super- and hyper- quenching of the fluorescence of the donor moieties by the nanometals and their probable applications in sensing. Rationalization has been made for the nanoparticle induced huge enhancement in the quenching efficiency. The impact of this review lies in the possible application of these amplified quenching processes in designing high sensitive chemical and biological sensors. - Highlights: • Super efficient quenching of fluorescence of probes by gold and silver nanoparticles is highlighted. • The amplified fluorescence quenching of dyes and polymers is rationalized. • Energy transfer is assigned to be responsible for the efficient quenching process. • Amplified quenching has its potential use in designing sensitive chemical/biological sensors

  19. Highly Sensitive Fluorescent Sensor for Cartap Based on Fluorescence Resonance Energy Transfer Between Gold Nanoparticles and Rhodamine B.

    Science.gov (United States)

    Dong, Liang; Hou, Changjun; Fa, Huanbao; Yang, Mei; Wu, Huixiang; Zhang, Liang; Huo, Danqun

    2018-04-01

    Cartap residue poses a great threat to human health and its derivatives would remain in soils, natural waters and other environmental domains for a long time. Herein, a simple, rapid and ultrasensitive analytical method for the determination of cartap based on fluorescence resonance energy transfer (FRET) between Au nanoparticles (AuNPs) and rhodamine B (RB) is first described. With the presence of citrate-stabilized AuNPs, the fluorescence of RB was remarkably quenched by AuNPs via FRET. The fluorescence of the AuNPs-RB system was recovered upon addition of cartap, cartap can be adsorbed on the surface of AuNPs due to its amino group that has good affinity with gold, which could induce the aggregation of AuNPs accompanying color change from red to blue. Thus, the FRET between AuNPs and RB was weakened and the PL intensity of RB was recovered accordingly. A good linear correlation for detection of RB was exhibited from 1 nM to 180 nM, and the detection limit reached 0.88 nM, which was much lower than the safety limit required by USA, UK and China. To the best of our knowledge, it has been the lowest detection ever without the aid of costly instrumentation. This method was successfully carried out for the assessment of cartap in real samples with satisfactory results, which revealed many advantages such as high sensitivity, low cost and non-time-consuming compared with traditional methods.

  20. How to measure separation and angles between inter-molecular fluorescent markers

    DEFF Research Database (Denmark)

    Flyvbjerg, Henrik

    Structure and function of an individual biomolecule can be explored with minimum two fluorescent markers of different colors. Since the light of such markers can be spec- trally separated and imaged simultaneously, the markers can be colocalized. Here, we describe the method used for such two......-color colocalization microscopy. Then we extend it to fluorescent markers with fixed orientations and in intramolecular proximity. Our benchmarking of this extension produced two extra results: (a) we established short double-labeled DNA molecules as probes of 3D orientation of anything to which one can attach them...

  1. Fluorescence Behavior and Dural Infiltration of Meningioma Analyzed by 5-Aminolevulinic Acid-Based Fluorescence: Operating Microscope Versus Mini-Spectrometer.

    Science.gov (United States)

    Knipps, Johannes; Beseoglu, Kerim; Kamp, Marcel; Fischer, Igor; Felsberg, Joerg; Neumann, Lisa M; Steiger, Hans-Jakob; Cornelius, Jan F

    2017-12-01

    To compare fluorescence intensity of tumor specimens, as measured by a fluorescence-guided surgery microscope and a spectrometer, to evaluate tumor infiltration of dura mater around meningiomas with help of these 2 different 5-aminolevulinic acid (5-ALA)-based fluorescence tools, and to correlate fluorescence intensity with histopathologic data. In a clinical series, meningiomas were resected by 5-ALA fluorescence-guided surgery. Fluorescence intensity was semiquantitatively rated by the surgeon at predefined points. Biopsies were harvested and fluorescence intensity measured by a spectrometer and histopathologically analyzed. Sampling was realized at the level of the dura in a centrifugal direction. A total of 104 biopsies (n = 13 tumors) were analyzed. Specificity and sensitivity of the microscope were 0.96 and 0.53 and of the spectrometer 0.95 and 0.93, respectively. Fluorescence intensity as measured by the spectrometer was correlated to histologically confirmed tumor burden. In a centrifugal direction, tumor burden and fluorescence intensity continuously decreased (along the dural tail). Below a threshold value of 639 arbitrary units no tumor was histologically detectable. At the level of the dura the spectrometer was highly sensitive for detection of meningioma cells. The surgical microscope showed false negative results and missed residual tumor cells in more than one half of the cases. The complementary use of both fluorescence tools may improve resection quality. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Towards the molecular bases of polymerase dynamics

    International Nuclear Information System (INIS)

    Chela Flores, J.

    1991-03-01

    One aspect of the strong relationship that is known to exist between the processes of DNA replication and transcription is manifest in the coupling of the rates of movement of the replication fork (r f ) and RNA polymerase (r t ). We address two issues concerning the largely unexplored area of polymerase dynamics: (i) The validity of an approximate kinematic formula linking r f and r t suggested by experiments in which transcription is initiated in some prokaryotes with the antibiotic streptolydigin, and (ii) What are the molecular bases of the kinematic formula? An analysis of the available data suggests possible molecular bases for polymerase dynamics. In particular, we are led to a hypothesis: In active chromatin r t may depend on the length (λ t ) of the transcript of the primary messenger RNA (pre-mRNA). This new effect is subject to experimental verification. We discuss possible experiments that may be performed in order to test this prediction. (author). Refs, 6 tabs

  3. A Fluorescence Based Miniaturized Detection Module for Toxin Producing Algae

    Science.gov (United States)

    Zieger, S. E.; Mistlberger, G.; Troi, L.; Lang, A.; Holly, C.; Klimant, I.

    2016-12-01

    Algal blooms are sensitive to external environmental conditions and may pose a serious threat to marine and human life having an adverse effect on the ecosystem. Harmful algal blooms can produce different toxins, which can lead to massive fish kills or to human disorders. Facing these problems, miniaturized and low-cost instrumentation for an early detection and identification of harmful algae classes has become more important over the last years. 1,2Based on the characteristic pigment pattern of different algae classes, we developed a miniaturized detection module, which is able to detect and identify algae classes after analyzing their spectral behavior. Our device combines features of a flow-cytometer and fluorimeter and is build up as a miniaturized and low-cost device of modular design. Similar to a fluorimeter, it excites cells in the capillary with up to 8 different excitation wavelengths recording the emitted fluorescence at 4 different emission channels. Furthermore, the device operates in a flow-through mode similar to a flow-cytometer, however, using only low-cost elements such as LEDs and photodiodes. Due to its miniaturized design, the sensitivity and selectivity increase, whereas background effects are reduced. With a sampling frequency of 140 Hz, we try to detect and count particular cell events even at a concentration of 2 cells / 7.3 µL illuminated volume. Using a self-learning multivariate algorithm, the data are evaluated autonomously on the device enabling an in-situ analysis. The flexibility in choosing excitation and emission wavelengths as well as the high sampling rate enables laboratory applications such as measuring induction kinetics. However, in its first application, the device is part of an open and modular monitoring system enabling the sensing of chemical compounds such as toxic and essential Hg, Cd, Pb, As and Cu trace metal species, nutrients and species related to the carbon cycle, VOCs and potentially toxic algae classes (FP7

  4. Fluorescence quantum yields of natural organic matter and organic compounds: Implications for the fluorescence-based interpretation of organic matter composition

    DEFF Research Database (Denmark)

    Wünsch, Urban; Murphy, Kathleen R.; Stedmon, Colin

    2015-01-01

    to more than 200 modeled spectra (PARAFAC components) in the OpenFluor database. Apparent matches, based on spectral similarity, were subsequently evaluated using molar fluorescence and absorbance. Five organic compounds were potential matches with PARAFAC components from 16 studies; however, the ability......Absorbance and fluorescence spectroscopy are economical tools for tracing the supply, turnover and fate of dissolved organic matter (DOM). The colored and fluorescent fractions of DOM (CDOM and FDOM, respectively) are linked by the apparent fluorescence quantum yield (AQY) of DOM, which reflects...... the likelihood that chromophores emit fluorescence after absorbing light. Compared to the number of studies investigating CDOM and FDOM, few studies have systematically investigated AQY spectra for DOM, and linked them to fluorescence quantum yields (Φ) of organic compounds. To offer a standardized approach...

  5. Progress on RNAi-based molecular medicines

    OpenAIRE

    Chen, Jing; Xie, Jianping

    2012-01-01

    Jing Chen, Jianping XieInstitute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Ministry of Education Eco-Environment of the Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, ChinaAbstract: RNA interference (RNAi) is a promising strategy to suppress the expression of disease-relevant genes and induce post-transcriptional gene silencing. Their simplicity and stability endow RNAi with great advantages in molecular medicine. Several RNA...

  6. Multiplex competitive microbead-based flow cytometric immunoassay using quantum dot fluorescent labels

    International Nuclear Information System (INIS)

    Yu, Hye-Weon; Kim, In S.; Niessner, Reinhard; Knopp, Dietmar

    2012-01-01

    Highlights: ► First time, duplex competitive bead-based flow cytometric immunoassay was developed using ODs. ► Antibody-coated QD detection probes and antigen-immobilized microspheres were synthesized. ► The two model target analytes were low molecular weight compounds of microbial and chemical origin. ► The determination of different water types was possible after simple filtration of samples. - Abstract: In answer to the ever-increasing need to perform the simultaneous analysis of environmental hazards, microcarrier-based multiplex technologies show great promise. Further integration with biofunctionalized quantum dots (QDs) creates new opportunities to extend the capabilities of multicolor flow cytometry with their unique fluorescence properties. Here, we have developed a competitive microbead-based flow cytometric immunoassay using QDs fluorescent labels for simultaneous detection of two analytes, bringing the benefits of sensitive, rapid and easy-of-manipulation analytical tool for environmental contaminants. As model target compounds, the cyanobacterial toxin microcystin-LR and the polycyclic aromatic hydrocarbon compound benzo[a]pyrene were selected. The assay was carried out in two steps: the competitive immunological reaction of multiple targets using their exclusive sensing elements of QD/antibody detection probes and antigen-coated microsphere, and the subsequent flow cytometric analysis. The fluorescence of the QD-encoded microsphere was thus found to be inversely proportional to target analyte concentration. Under optimized conditions, the proposed assay performed well within 30 min for the identification and quantitative analysis of the two environmental contaminants. For microcystin-LR and benzo[a]pyrene, dose–response curves with IC 50 values of 5 μg L −1 and 1.1 μg L −1 and dynamic ranges of 0.52–30 μg L −1 and 0.13–10 μg L −1 were obtained, respectively. Recovery was 92.6–106.5% for 5 types of water samples like bottled

  7. Two-Photon Absorption Properties of Gold Fluorescent Protein: A Combined Molecular Dynamics and Quantum Chemistry Study.

    Science.gov (United States)

    Simsek, Yusuf; Brown, Alex

    2018-05-09

    Molecular dynamic (MD) simulations were carried out to obtain the conformational changes of the chromophore in the gold fluorescent protein (PDB ID: 1OXF). To obtain two-photon absorption (TPA) cross-sections, time dependent density functional theory (TD-DFT) computations were performed for chromophore geometries sampled along the trajectory. The TD-DFT computations used the CAM-B3LYP functional and 6-31+G(d) basis set with the conductor-like polarizable continuum model (PCM) with parameters for water. Results showed that two dihedral angles change remarkably over the simulation time. TPA cross-sections were found to average 20 GM for the excitation to S1 between 430 and 460 nm; however, the maximal and minimal values were 35GM and 5GM, respectively. Besides the effects of the dihedrals on the spectroscopic properties, some bond lengths affected the excitation energies and the TPA cross-sections significantly (up to ±25-30%) while the effects of bond angles were smaller (±5%). Overall the present results provide insight in the effects of conformational exibility on TPA (with gold fluorescent protein as a specific example) and suggest that further experimental measurements of TPA for gold fluorescent protein should be undertaken.

  8. Adaptation of Tri-molecular fluorescence complementation allows assaying of regulatory Csr RNA-protein interactions in bacteria.

    Science.gov (United States)

    Gelderman, Grant; Sivakumar, Anusha; Lipp, Sarah; Contreras, Lydia

    2015-02-01

    sRNAs play a significant role in controlling and regulating cellular metabolism. One of the more interesting aspects of certain sRNAs is their ability to make global changes in the cell by interacting with regulatory proteins. In this work, we demonstrate the use of an in vivo Tri-molecular Fluorescence Complementation assay to detect and visualize the central regulatory sRNA-protein interaction of the Carbon Storage Regulatory system in E. coli. The Carbon Storage Regulator consists primarily of an RNA binding protein, CsrA, that alters the activity of mRNA targets and of an sRNA, CsrB, that modulates the activity of CsrA. We describe the construction of a fluorescence complementation system that detects the interactions between CsrB and CsrA. Additionally, we demonstrate that the intensity of the fluorescence of this system is able to detect changes in the affinity of the CsrB-CsrA interaction, as caused by mutations in the protein sequence of CsrA. While previous methods have adopted this technique to study mRNA or RNA localization, this is the first attempt to use this technique to study the sRNA-protein interaction directly in bacteria. This method presents a potentially powerful tool to study complex bacterial RNA protein interactions in vivo. © 2014 Wiley Periodicals, Inc.

  9. Investigation of three flavonoids binding to bovine serum albumin using molecular fluorescence technique

    International Nuclear Information System (INIS)

    Bi Shuyun; Yan Lili; Pang Bo; Wang Yu

    2012-01-01

    The three flavonoids including naringenin, hesperetin and apigenin binding to bovine serum albumin (BSA) at pH 7.4 was studied by fluorescence quenching, synchronous fluorescence and UV-vis absorption spectroscopic techniques. The results obtained revealed that naringenin, hesperetin and apigenin strongly quenched the intrinsic fluorescence of BSA. The Stern-Volmer curves suggested that these quenching processes were all static quenching processes. At 291 K, the value and the order of the binding constant were K A n aringenin) =4.08x10 4 A(hesperetin) =5.40x10 4 ∼K A(apigenin) =5.32x10 4 L mol -1 . The main binding force between the flavonoid and BSA was hydrophobic and electrostatic force. According to the Foerster theory of non-radiation energy transfer, the binding distances (r 0 ) were obtained as 3.36, 3.47 and 3.30 nm for naringenin-BSA, hesperetin-BSA and apigenin-BSA, respectively. The effect of some common ions such as Fe 3+ , Cu 2+ , Mg 2+ , Mn 2+ , Zn 2+ and Ca 2+ on the binding was also studied in detail. The competition binding was also performed. The apparent binding constant (K' A ) obtained suggested that one flavonoid had an obvious effect on the binding of another flavonoid to protein when they coexisted in BSA solution. - Highlights: → Quenchings of BSA fluorescence by the flavonoids was all static quenchings. → Synchronous fluorescence was applied to study the structural change of BSA. → Binding constant, binding site and binding force were determined. → Competition binding experiments were performed. → One flavonoid had an obvious effect on the binding of another one to BSA.

  10. Molecular and structural characterization of fluorescent human parvovirus B19 virus-like particles

    International Nuclear Information System (INIS)

    Gilbert, Leona; Toivola, Jouni; White, Daniel; Ihalainen, Teemu; Smith, Wesley; Lindholm, Laura; Vuento, Matti; Oker-Blom, Christian

    2005-01-01

    Although sharing a T = 1 icosahedral symmetry with other members of the Parvoviridae family, it has been suggested that the fivefold channel of the human parvovirus B19 VP2 capsids is closed at its outside end. To investigate the possibility of placing a relatively large protein moiety at this site of B19, fluorescent virus-like particles (fVLPs) of B19 were developed. The enhanced green fluorescent protein (EGFP) was inserted at the N-terminus of the structural protein VP2 and assembly of fVLPs from this fusion protein was obtained. Electron microscopy revealed that these fluorescent protein complexes were very similar in size when compared to wild-type B19 virus. Further, fluorescence correlation spectroscopy showed that an average of nine EGFP domains were associated with these virus-like structures. Atomic force microscopy and immunoprecipitation studies showed that EGFP was displayed on the surface of these fVLPs. Confocal imaging indicated that these chimeric complexes were targeted to late endosomes when expressed in insect cells. The fVLPs were able to efficiently enter cancer cells and traffic to the nucleus via the microtubulus network. Finally, immunoglobulins present in human parvovirus B19 acute and past-immunity serum samples were able to detect antigenic epitopes present in these fVLPs. In summary, we have developed fluorescent virus-like nanoparticles displaying a large heterologous entity that should be of help to elucidate the mechanisms of infection and pathogenesis of human parvovirus B19. In addition, these B19 nanoparticles serve as a model in the development of targetable vehicles designed for delivery of biomolecules

  11. A nanocluster-based fluorescent sensor for sensitive hemoglobin detection.

    Science.gov (United States)

    Yang, Dongqin; Meng, Huijie; Tu, Yifeng; Yan, Jilin

    2017-08-01

    In this report, a fluorescence sensor for sensitive detection of hemoglobin was developed. Gold nanoclusters were first synthesized with bovine serum albumin. It was found that both hydrogen peroxide and hemoglobin could weakly quench the fluorescence from the gold nanoclusters, but when these two were applied onto the nanolcusters simultaneously, a much improved quenching was resulted. This enhancing effect was proved to come from the catalytic generation of hydroxyl radical by hemoglobin. Under an optimized condition, the quenching linearly related to the concentration of hemoglobin in the range of 1-250nM, and a limit of detection as low as 0.36nM could be obtained. This provided a sensitive means for the quantification of Hb. The sensor was then successfully applied for blood analyses with simple sample pretreatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

    Science.gov (United States)

    Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan

    2017-06-01

    A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

  13. Angular shaping of fluorescence from synthetic opal-based photonic crystal.

    Science.gov (United States)

    Boiko, Vitalii; Dovbeshko, Galyna; Dolgov, Leonid; Kiisk, Valter; Sildos, Ilmo; Loot, Ardi; Gorelik, Vladimir

    2015-01-01

    Spectral, angular, and temporal distributions of fluorescence as well as specular reflection were investigated for silica-based artificial opals. Periodic arrangement of nanosized silica globules in the opal causes a specific dip in the defect-related fluorescence spectra and a peak in the reflectance spectrum. The spectral position of the dip coincides with the photonic stop band. The latter is dependent on the size of silica globules and the angle of observation. The spectral shape and intensity of defect-related fluorescence can be controlled by variation of detection angle. Fluorescence intensity increases up to two times at the edges of the spectral dip. Partial photobleaching of fluorescence was observed. Photonic origin of the observed effects is discussed.

  14. A highly sensitive fluorescent probe based on BODIPY for Hg2+ in aqueous solution

    Directory of Open Access Journals (Sweden)

    ZHAO Junwei

    2016-12-01

    Full Text Available A highly sensitive fluorescent probe based on BODIPY and hydrazine for Hg2+ was designed and synthesized.This probe could detect mercury ions in aqueous solutions within 5 min.With the increase of Hg2+ mole concentration,an obvious red shift of UV-Vis absorption wavelength was observed and the fluorescence intensity significantly enhanced.It was found that the fluorescence intensity of an aqueous solution containing 0.1 μmol/L Hg2+ is much stronger than that of blank solution,which indicats that the fluorescent probe has high sensitivity.In addition,other metal ions could not cause the change of fluorescent spectra,which means this probe has good selectivity,as well.

  15. Fluorescence Endoscopy in vivo based on Fiber-bundle Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Zufiria, B.; Gomez-Garcia, P.; Stamatakis, K.; Vaquero, J.J.; Fresno, M.; Desco, M.; Ripoll, J.; Arranz, A.

    2016-07-01

    High-resolution imaging techniques have become important for the determination of the cellular organization that is coupled to organ function. In many cases the organ can be viewed without the need of ionizing radiation techniques in an easier way. This is the case of the gastrointestinal tract, an organ that can be directly accessed with endoscopy avoiding any invasive procedure. Here we describe the design, assembly and testing of a fluorescence high-resolution endoscope intended for the study of the cellular organization of the colon in an experimental mouse model of colon carcinoma. Access to the colon of the mouse took place using a fiber-optic bundle that redirects the light coming from a LED to produce fluorescence and detect it back through the fiber bundle. Results from in vivo and ex-vivo test using our fluorescence fiber bundle endoscope show altered tissue structure and destruction of the intestinal crypts in tumor-bearing areas compared with healthy tissue. (Author)

  16. Fluorescent Protein Approaches in Alpha Herpesvirus Research

    Directory of Open Access Journals (Sweden)

    Ian B. Hogue

    2015-11-01

    Full Text Available In the nearly two decades since the popularization of green fluorescent protein (GFP, fluorescent protein-based methodologies have revolutionized molecular and cell biology, allowing us to literally see biological processes as never before. Naturally, this revolution has extended to virology in general, and to the study of alpha herpesviruses in particular. In this review, we provide a compendium of reported fluorescent protein fusions to herpes simplex virus 1 (HSV-1 and pseudorabies virus (PRV structural proteins, discuss the underappreciated challenges of fluorescent protein-based approaches in the context of a replicating virus, and describe general strategies and best practices for creating new fluorescent fusions. We compare fluorescent protein methods to alternative approaches, and review two instructive examples of the caveats associated with fluorescent protein fusions, including describing several improved fluorescent capsid fusions in PRV. Finally, we present our future perspectives on the types of powerful experiments these tools now offer.

  17. Intermolecular G-quadruplex structure-based fluorescent DNA detection system.

    Science.gov (United States)

    Zhou, Hui; Wu, Zai-Sheng; Shen, Guo-Li; Yu, Ru-Qin

    2013-03-15

    Adopting multi-donors to pair with one acceptor could improve the performance of fluorogenic detection probes. However, common dyes (e.g., fluorescein) in close proximity to each other would self-quench the fluorescence, and the fluorescence is difficult to restore. In this contribution, we constructed a novel "multi-donors-to-one acceptor" fluorescent DNA detection system by means of the intermolecular G-quadruplex (IGQ) structure-based fluorescence signal enhancement combined with the hairpin oligonucleotide. The novel IGQ-hairpin system was characterized using the p53 gene as the model target DNA. The proposed system showed an improved assay performance due to the introduction of IGQ-structure into fluorescent signaling probes, which could inhibit the background fluorescence and increase fluorescence restoration amplitude of fluoresceins upon target DNA hybridization. The proof-of-concept scheme is expected to provide new insight into the potential of G-quadruplex structure and promote the application of fluorescent oligonucleotide probes in fundamental research, diagnosis, and treatment of genetic diseases. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Pre-recombination quenching of the radiation induced fluorescence as the approach to study kinetics of ion-molecular reactions

    International Nuclear Information System (INIS)

    Borovkov, V.I.; Ivanishko, I.S.

    2011-01-01

    This study deals with the geminate ion recombination in the presence of bulk scavengers, that is the so-called scavenger problem, as well as with the effect of the scavenging reaction on the radiation-induced recombination fluorescence. have proposed a method to determine the rate constant of the bulk reaction between neutral scavengers and one of the geminate ions if the ion-molecular reaction prevented the formation of electronically excited states upon recombination involving a newly formed ion. If such pre-recombination quenching of the radiation-induced fluorescence took place, it manifested itself as a progressive decrease in the decay of the fluorescence intensity. The relative change in the fluorescence decay as caused by the scavengers was believed to be closely related to the kinetics of the scavenging reaction. The goal of the present study is to support this method, both computationally and experimentally because there are two factors, which cast doubt on the intuitively obvious approach to the scavenger problem: spatial correlations between the particles involved and the drift of the charged reagent in the electric field of its geminate partner. Computer simulation of geminate ions recombination with an explicit modeling of the motion trajectories of scavengers has been performed for media of low dielectric permittivity, i.e. for the maximal Coulomb interaction between the ions. The simulation has shown that upon continuous diffusion of the particles involved, the joint effect of the two above factors can be considered as insignificant with a high accuracy. Besides, it is concluded then that the method of pre-recombination quenching could be applied to study parallel and consecutive reactions where the yields of excited states in the reaction pathways are different with the use of very simple analytical relations of the formal chemical kinetics. The conclusion has been confirmed experimentally by the example of the reactions of electron transfer from

  19. DHA-fluorescent probe is sensitive to membrane order and reveals molecular adaptation of DHA in ordered lipid microdomains☆

    Science.gov (United States)

    Teague, Heather; Ross, Ron; Harris, Mitchel; Mitchell, Drake C.; Shaikh, Saame Raza

    2012-01-01

    Docosahexaenoic acid (DHA) disrupts the size and order of plasma membrane lipid microdomains in vitro and in vivo. However, it is unknown how the highly disordered structure of DHA mechanistically adapts to increase the order of tightly packed lipid microdomains. Therefore, we studied a novel DHA-Bodipy fluorescent probe to address this issue. We first determined if the DHA-Bodipy probe localized to the plasma membrane of primary B and immortal EL4 cells. Image analysis revealed that DHA-Bodipy localized into the plasma membrane of primary B cells more efficiently than EL4 cells. We then determined if the probe detected changes in plasma membrane order. Quantitative analysis of time-lapse movies established that DHA-Bodipy was sensitive to membrane molecular order. This allowed us to investigate how DHA-Bodipy physically adapted to ordered lipid microdomains. To accomplish this, we employed steady-state and time-resolved fluorescence anisotropy measurements in lipid vesicles of varying composition. Similar to cell culture studies, the probe was highly sensitive to membrane order in lipid vesicles. Moreover, these experiments revealed, relative to controls, that upon incorporation into highly ordered microdomains, DHA-Bodipy underwent an increase in its fluorescence lifetime and molecular order. In addition, the probe displayed a significant reduction in its rotational diffusion compared to controls. Altogether, DHA-Bodipy was highly sensitive to membrane order and revealed for the first time that DHA, despite its flexibility, could become ordered with less rotational motion inside ordered lipid microdomains. Mechanistically, this explains how DHA acyl chains can increase order upon formation of lipid microdomains in vivo. PMID:22841541

  20. Phenylboronic acid functionalized reduced graphene oxide based fluorescence nano sensor for glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Basiruddin, SK; Swain, Sarat K., E-mail: swainsk2@yahoo.co.in

    2016-01-01

    Reduced graphene has emerged as promising tools for detection based application of biomolecules as it has high surface area with strong fluorescence quenching property. We have used the concept of fluorescent quenching property of reduced graphene oxide to the fluorescent probes which are close vicinity of its surface. In present work, we have synthesized fluorescent based nano-sensor consist of phenylboronic acid functionalized reduced graphene oxide (rGO–PBA) and di-ol modified fluorescent probe for detection of biologically important glucose molecules. This fluorescent graphene based nano-probe has been characterized by high resolution transmission electron microscope (HRTEM), Atomic force microscope (AFM), UV–visible, Photo-luminescence (PL) and Fourier transformed infrared (FT-IR) spectroscopy. Finally, using this PBA functionalized reduced GO based nano-sensor, we were able to detect glucose molecule in the range of 2 mg/mL to 75 mg/mL in aqueous solution of pH 7.4. - Highlights: • Easy and simple synthesis of PBA functionalized reduced GO based nano probe. • PBA functionalized reduced GO graphene based nano-probes are characterized. • PBA functionalized reduced GO nano probe is used to detect glucose molecules. • It is very cost-effective and enzyme-free detection of glucose in solution.

  1. Simulation and application of micro X-ray fluorescence based on an ellipsoidal capillary

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jing; Li, Yude; Wang, Xingyi; Zhang, Xiaoyun; Lin, Xiaoyan, E-mail: yangjing_928@126.com

    2017-06-15

    Highlights: • A micro X-ray fluorescence setup based on an ellipsoidal capillary was presented. • The optimal parameters of ellipsoidal capillary were designed. • The 2D mapping image of biological sample was obtained. - Abstract: A micro X-ray fluorescence setup was presented, based on an ellipsoidal capillary and a traditional laboratorial X-ray source. Using Ray-tracing principle, we have simulated the transmission path of X-ray beam in the ellipsoidal capillary and designed the optimal parameters of the ellipsoidal capillary for the micro X-ray fluorescence setup. We demonstrate that ellipsoidal capillary is well suited as condenser for the micro X-ray fluorescence based on traditional laboratorial X-ray source. Furthermore, we obtain the 2D mapping image of the leaf blade sample by using the ellipsoidal capillary we designed.

  2. High sensitive determination of zinc with novel water-soluble small molecular fluorescent sensor

    International Nuclear Information System (INIS)

    Weng Ying; Chen Zilin; Wang Fang; Xue Lin; Jiang Hua

    2009-01-01

    A high sensitive method of quantitative analysis for the determination of zinc in the nutrition supplements has been developed by using a novel water-soluble fluorescent sensor HQ3: (8-pyridylmethyloxy-2-methyl-quinoline). Under the optimized condition of 67 mM phosphate buffer, pH 7.4, and 5% (v/v) DMSO, the zinc concentration showed good linear relationship with fluorescence intensity in the range of 7.5 x 10 -8 to 2.5 x 10 -5 M with the detection limit of 1.5 x 10 -8 M. HQ3 exhibited high selectivity to zinc comparing with other metal ions except for cadmium. The developed analytical method was successfully used for determining the content of zinc in a real sample of zinc gluconate solution of Sanchine.

  3. A fluorescence study of the molecular interactions of harmane with the nucleobases, their nucleosides and mononucleotides.

    Science.gov (United States)

    Balón, M; Muñoz, M A; Carmona, C; Guardado, P; Galán, M

    1999-07-19

    Fluorescence binding studies of harmane to the elemental components of the nucleic acids were undertaken to investigate the origin of the interaction between the drug and DNA. Most of the tested substrates have been found to induce hypochromism in the absorption spectrum of harmane and to quench its fluorescence. The quenching process induced by the nucleobases and their nucleosides is mainly due to the formation of ground state 1:1 complexes. However, in the case of the mononucleotides a dynamic quenching component is also observed. This quenching component is likely due to the excited state interaction of harmane with the phosphate group of the nucleotides. UV-vis spectral changes and quenching measurements have been used to quantify the ground state association constants of the complexes and the quenching rate constants.

  4. Energetics and dynamics of the non-natural fluorescent 4AP:DAP base pair

    KAUST Repository

    Chawla, Mohit

    2018-01-02

    The fluorescent non-natural 4-aminophthalimide (4AP) base, when paired to the complementary 2,4-diaminopyrimidine (DAP) nucleobase, is accommodated in a B-DNA duplex being efficiently recognized and incorporated by DNA polymerases. To complement the experimental studies and rationalize the impact of the above non-natural bases on the structure, stability and dynamics of nucleic acid structures, we performed quantum mechanics (QM) calculations along with classical molecular dynamics (MD) simulations. QM calculations were initially focused on the geometry and energetics of the 4AP:DAP non-natural pair and of H-bonded base pairs between 4AP and all the natural bases in their classical Watson-Crick geometries. The QM calculations indicate that the 4AP:DAP pair, despite the fact that it can form 3 H-bonds in a classic Watson-Crick geometry, has a stability comparable to the A:T pair. Then, we extended the study to reverse Watson-Crick geometries, characteristic of parallel strands. MD simulations were carried out on two 13-mer DNA duplexes, featuring a central 4AP:DAP or A:T pair, respectively. No major structural deformation of the duplex was observed during the MD simulation. Snapshots from the MD simulations were subjected to QM calculations to investigate the 4AP:DAP interaction energy when embedded into a duplex structure, and to investigate the impact of the two non-natural bases on the stacking interactions with adjacent bases in the DNA duplex. We found a slight increase in stacking interactions involving the 4AP:DAP pair, counterbalanced by a moderate decrease in H-bonding interactions of the 4AP:DAP and of the adjacent base pairs in the duplex. The results of our study are in agreement with experimental data and complement them by providing an insight into which factors contribute positively and which factors contribute negatively to the structural compatibility of the fluorescent 4AP:DAP pair with a B-DNA structure.

  5. A Novel Molecular Fluorescent Technique for Imaging the Somatostatin Receptor 2, Using a DOTATOC Lanthanide Conjugate

    DEFF Research Database (Denmark)

    Andersen, Rune Wiik; Prakash, Vineet; Stensballe, Allan

    -functional DOTATOC component.                       METHOD AND MATERIALS            The chelation of Europium and Samarium to DOTATOC was proven using MALDI-TOF Mass Spectrometry. The rise in quantum yield between unchelated lanthanides and those bound by DOTATOC was examined using fluorescence spectroscopy...

  6. A novel clinically translatable fluorescent nanoparticle for targeted molecular imaging of tumors in living subjects.

    Science.gov (United States)

    Gao, Jinhao; Chen, Kai; Luong, Richard; Bouley, Donna M; Mao, Hua; Qiao, Tiecheng; Gambhir, Sanjiv S; Cheng, Zhen

    2012-01-11

    The use of quantum dots (QDs) in biomedical research has grown tremendously, yet successful examples of clinical applications are absent due to many clinical concerns. Here, we report on a new type of stable and biocompatible dendron-coated InP/ZnS core/shell QD as a clinically translatable nanoprobe for molecular imaging applications. The QDs (QD710-Dendron) were demonstrated to hold several significant features: near-infrared (NIR) emission, high stability in biological media, suitable size with possible renal clearance, and ability of extravasation. More importantly, a pilot mouse toxicity study confirmed that QD710-Dendron lacks significant toxicity at the doses tested. The acute tumor uptake of QD710-Dendron resulted in good contrast from the surrounding nontumorous tissues, indicating the possibility of passive targeting of the QDs. The highly specific targeting of QD710-Dendron-RGD(2) to integrin α(v)β(3)-positive tumor cells resulted in high tumor uptake and long retention of the nanoprobe at tumor sites. In summary, QD710-Dendron and RGD-modified nanoparticles demonstrate small size, high stability, biocompatibility, favorable in vivo pharmacokinetics, and successful tumor imaging properties. These features satisfy the requirements for clinical translation and should promote efforts to further investigate the possibility of using QD710-Dendron-based nanoprobes in the clinical setting in the near future. © 2011 American Chemical Society

  7. Label free selective detection of estriol using graphene oxide-based fluorescence sensor

    Science.gov (United States)

    Kushwaha, H. S.; Sao, Reshma; Vaish, Rahul

    2014-07-01

    Water-soluble and fluorescent Graphene oxide (GO) is biocompatible, easy, and economical to synthesize. Interestingly, GO is also capable of quenching fluorescence. On the basis of its fluorescence and quenching abilities, GO has been reported to serve as an energy acceptor in a fluorescence resonance energy transfer (FRET) sensor. GO-based FRET biosensors have been widely reported for sensing of proteins, nucleic acid, ATP (Adenosine triphosphate), etc. GO complexes with fluorescent dyes and enzymes have been used to sense metal ions. Graphene derivatives have been used for sensing endocrine-disrupting chemicals like bisphenols and chlorophenols with high sensitivity and good reproducibility. On this basis, a novel GO based fluorescent sensor has been successfully designed to detect estriol with remarkable selectivity and sensitivity. Estriol is one of the three estrogens in women and is considered to be medically important. Estriol content of maternal urine or plasma acts as an important screening marker for estimating foetal growth and development. In addition, estriol is also used as diagnostic marker for diseases like breast cancer, osteoporosis, neurodegenerative and cardiovascular diseases, insulin resistance, lupus erythematosus, endometriosis, etc. In this present study, we report for the first time a rapid, sensitive with detection limit of 1.3 nM, selective and highly biocompatible method for label free detection of estriol under physiological conditions using fluorescence assay.

  8. Graphene oxide based photoinduced charge transfer label-free near-infrared fluorescent biosensor for dopamine.

    Science.gov (United States)

    Chen, Jin-Long; Yan, Xiu-Ping; Meng, Kang; Wang, Shu-Feng

    2011-11-15

    While the super fluorescence quenching capacity of graphene and graphene oxide (GO) has been extensively employed to develop fluorescent sensors, their own unique fluorescence and its potential for chemo-/biosensing have seldom been explored. Here we report a GO-based photoinduced charge transfer (PCT) label-free near-infrared (near-IR) fluorescent biosensor for dopamine (DA). The multiple noncovalent interactions between GO and DA and the ultrafast decay at the picosecond range of the near-IR fluorescence of GO resulted in effective self-assembly of DA molecules on the surface of GO, and significant fluorescence quenching, allowing development of a PCT-based biosensor with direct readout of the near-IR fluorescence of GO for selective and sensitive detection of DA. The developed method gave a detection limit of 94 nM and a relative standard deviation of 2.0% for 11 replicate detections of 2.0 μM DA and was successfully applied to the determination of DA in biological fluids with quantitative recovery (98-115%).

  9. Plasmonic-based instrument response function for time-resolved fluorescence: toward proper lifetime analysis

    Energy Technology Data Exchange (ETDEWEB)

    Szlazak, Radoslaw; Tutaj, Krzysztof; Grudzinski, Wojciech; Gruszecki, Wieslaw I.; Luchowski, Rafal, E-mail: rafal.luchowski@umcs.pl [Maria Curie-Sklodowska University, Department of Biophysics, Institute of Physics (Poland)

    2013-06-15

    In this report, we investigated the so-called plasmonic platforms prepared to target ultra-short fluorescence and accurate instrumental response function in a time-domain spectroscopy and microscopy. The interaction of metallic nanoparticles with nearby fluorophores results in the increase of the dye fluorescence quantum yield, photostability and decrease of the lifetime parameter. The mentioned properties of platforms were applied to achieve a picosecond fluorescence lifetime (21 ps) of erythrosin B, used later as a better choice for deconvolution of fluorescence decays measured with 'color' sensitive photo-detectors. The ultra-short fluorescence standard based on combination of thin layers of silver film, silver colloidal nanoparticles (about 60 nm in diameter), and top layer of erythrosin B embedded in 0.2 % poly(vinyl) alcohol. The response functions were monitored on two photo-detectors; microchannel plate photomultiplier and single photon avalanche photodiode as a Rayleigh scattering and ultra-short fluorescence. We demonstrated that use of the plasmonic base fluorescence standard as an instrumental response function results in the absence of systematic error in lifetime measurements and analysis.

  10. A ratiometric nanoprobe based on silver nanoclusters and carbon dots for the fluorescent detection of biothiols

    Science.gov (United States)

    Zhang, Shuming; Lin, Bixia; Yu, Ying; Cao, Yujuan; Guo, Manli; Shui, Lingling

    2018-04-01

    Ratiometric fluorescent probes could eliminate the influence from experimental factors and improve the detection accuracy. In this article, a ratiometric nanoprobe was constructed based on silver nanoclusters (AgNCs) with nitrogen-doped carbon dots (NCDs) and used for the detection of biothiols. The fluorescence peak of AgNCs was observed at 650 nm with excitation wavelength at 370 nm. In order to construct the ratiometric fluorescent probe, NCDs with the excitation and emission wavelengths at 370 nm and 450 nm were selected. After adding AgNCs, the fluorescence of NCDs was quenched. The mechanism of the fluorescence quenching was studied by fluorescence, UV-Vis absorption and the fluorescence lifetime spectra. The results indicated that the quenching could be ascribed to the inner filter effect (IFE). With the addition of biothiols, the fluorescence of AgNCs at 650 nm decreased due to the breakdown of AgNCs, and the fluorescence of NCDs at 450 nm recovered accordingly. Thus, the relationship between the ratio of the fluorescence intensities (I450/I650) and biothiol concentration was used to establish the determination method for biothiols. Cysteine (Cys) was taken as the model of biothiols, and the working curve for Cys was I450/I650 = 0.60CCys - 1.86 (CCys: μmol/L) with the detection limit of 0.14 μmol/L (S/N = 3). Then, the method was used for the detection of Cys in human urine and serum samples with satisfactory accuracy and recovery ratios. Furthermore, the probe could be applied for the visual semi-quantitative determination of Cys by naked eyes.

  11. [A cell-based detection of ciguatoxin using sodium fluorescence probe].

    Science.gov (United States)

    Yuan, Jian-hui; Yang, Hui; Tang, Huan-wen; Huang, Wei; Xu, Xin-yun; Liu, Jian-jun; Ke, Yue-bin; Cheng, Jin-quan; Zhuang, Zhi-xiong

    2011-04-01

    To establish a cell-based detection method of ciguatoxin using fluorescence assay. Mouse neuroblastoma N-2A cells were exposed to ouabain and veratridine and different concentrations of standard ciguatoxin samples (P-CTX-1) to establish the curvilinear relationship between the toxin dosage and fluorescence intensity using the sodium fluorescence probe CoroNaTM Green. The toxicity curvilinear relationship was also generated between the toxin dosage and cell survival using CCK-8 method. Based on these standard curves, the presence of ciguatoxin was detected in 33 samples of deep-sea coral fish. A correlation was found between the detection results of cell-based fluorescence assay and cytotoxicity assay, whose detection limit reached 103 g/ml and 1012 g/ml, respectively. The cell-based fluorescent assay sensitivity showed a higher sensitivity than cytotoxicity assay with a 2-4 h reduction of the detection time. The cell-based fluorescent assay can quickly and sensitively detect ciguatoxin and may serve as a good option for preliminary screening of the toxin.

  12. Resonance fluorescence based two- and three-dimensional atom localization

    Science.gov (United States)

    Wahab, Abdul; Rahmatullah; Qamar, Sajid

    2016-06-01

    Two- and three-dimensional atom localization in a two-level atom-field system via resonance fluorescence is suggested. For the two-dimensional localization, the atom interacts with two orthogonal standing-wave fields, whereas for the three-dimensional atom localization, the atom interacts with three orthogonal standing-wave fields. The effect of the detuning and phase shifts associated with the corresponding standing-wave fields is investigated. A precision enhancement in position measurement of the single atom can be noticed via the control of the detuning and phase shifts.

  13. Spectrally-resolved response properties of the three most advanced FRET based fluorescent protein voltage probes.

    Directory of Open Access Journals (Sweden)

    Hiroki Mutoh

    Full Text Available Genetically-encoded optical probes for membrane potential hold the promise of monitoring electrical signaling of electrically active cells such as specific neuronal populations in intact brain tissue. The most advanced class of these probes was generated by molecular fusion of the voltage sensing domain (VSD of Ci-VSP with a fluorescent protein (FP pair. We quantitatively compared the three most advanced versions of these probes (two previously reported and one new variant, each involving a spectrally distinct tandem of FPs. Despite these different FP tandems and dissimilarities within the amino acid sequence linking the VSD to the FPs, the amplitude and kinetics of voltage dependent fluorescence changes were surprisingly similar. However, each of these fluorescent probes has specific merits when considering different potential applications.

  14. Toxicological evaluation of Cd-based fluorescent nanoprobes by means of in vivo studies

    Science.gov (United States)

    Farias, Patricia M. A.; Ma-Hock, Lan; Landsiedel, Robert; van Ravenzwaay, Bennard

    2018-02-01

    Cadmium still represents a stigma for many research- and/or industrial applications. Some deleterious effects are attributed to Cadmium. In the present work, highly fluorescent Cadmium sulfide quantum dots are investigated by e.g. physical-chemical characterization. Most important however is their application as fluorescent probes for bio-imaging in living cells and tissues. This work presents their toxicological evaluation by means of in vivo studies. Bio-imaging experiments are performed without any pre-treatment. The toxicological studies performed, strongly indicate that the use of Cadmium based nanoparticles as fluorescent probes may be nonhazardous and not induce side effects for cells/tissues.

  15. A dansyl-rhodamine ratiometric fluorescent probe for Hg2+ based on FRET mechanism.

    Science.gov (United States)

    Xie, Puhui; Guo, Fengqi; Wang, Lingyu; Yang, Sen; Yao, Denghui; Yang, Guoyu

    2015-03-01

    Based on resonance energy transfer (FRET) from dansyl to rhodamine 101, a new fluorescent probe (compound 1) containing rhodamine 101 and a dansyl unit was synthesized for detecting Hg(2+) through ratiometric sensing in DMSO aqueous solutions. This probe shows a fast, reversible and selective response toward Hg(2+) in a wide pH range. Hg(2+) induced ring-opening reactions of the spirolactam rhodamine moiety of 1, leading to the formation of fluorescent derivatives that can serve as the FRET acceptors. Very large stokes shift (220 nm) was observed in this case. About 97-fold increase in fluorescence intensity ratio was observed upon its binding with Hg(2+).

  16. A novel dansyl-based fluorescent probe for highly selective detection of ferric ions.

    Science.gov (United States)

    Yang, Min; Sun, Mingtai; Zhang, Zhongping; Wang, Suhua

    2013-02-15

    A novel dansyl-based fluorescent probe was synthesized and characterized. It exhibits high selectivity and sensitivity towards Fe(3+) ion. This fluorescent probe is photostable, water soluble and pH insensitive. The limit of detection is found to be 0.62 μM. These properties make it a good fluorescent probe for Fe(3+) ion detection in both chemical and biological systems. Spike recovery test confirms its practical application in tap water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Towards sensitive, high-throughput, biomolecular assays based on fluorescence lifetime

    Science.gov (United States)

    Ioanna Skilitsi, Anastasia; Turko, Timothé; Cianfarani, Damien; Barre, Sophie; Uhring, Wilfried; Hassiepen, Ulrich; Léonard, Jérémie

    2017-09-01

    Time-resolved fluorescence detection for robust sensing of biomolecular interactions is developed by implementing time-correlated single photon counting in high-throughput conditions. Droplet microfluidics is used as a promising platform for the very fast handling of low-volume samples. We illustrate the potential of this very sensitive and cost-effective technology in the context of an enzymatic activity assay based on fluorescently-labeled biomolecules. Fluorescence lifetime detection by time-correlated single photon counting is shown to enable reliable discrimination between positive and negative control samples at a throughput as high as several hundred samples per second.

  18. A Cu²⁺-selective fluorescent chemosensor based on BODIPY with two pyridine ligands and logic gate.

    Science.gov (United States)

    Huang, Liuqian; Zhang, Jing; Yu, Xiaoxiu; Ma, Yifan; Huang, Tianjiao; Shen, Xi; Qiu, Huayu; He, Xingxing; Yin, Shouchun

    2015-06-15

    A novel near-infrared fluorescent chemosensor based on BODIPY (Py-1) has been synthesized and characterized. Py-1 displays high selectivity and sensitivity for sensing Cu(2+) over other metal ions in acetonitrile. Upon addition of Cu(2+) ions, the maximum absorption band of Py-1 in CH3CN displays a red shift from 603 to 608 nm, which results in a visual color change from pink to blue. When Py-1 is excited at 600 nm in the presence of Cu(2+), the fluorescent emission intensity of Py-1 at 617 nm is quenched over 86%. Notably, the complex of Py-1-Cu(2+) can be restored with the introduction of EDTA or S(2-). Consequently, an IMPLICATION logic gate at molecular level operating in fluorescence mode with Cu(2+) and S(2-) as chemical inputs can be constructed. Finally, based on the reversible and reproducible system, a nanoscale sequential memory unit displaying "Writing-Reading-Erasing-Reading" functions can be integrated. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. A novel fluorescence probe based on triphenylamine Schiff base for bioimaging and responding to pH and Fe3+

    International Nuclear Information System (INIS)

    Wang, Lei; Yang, Xiaodong; Chen, Xiuli; Zhou, Yuping; Lu, Xiaodan; Yan, Chenggong; Xu, Yikai; Liu, Ruiyuan; Qu, Jinqing

    2017-01-01

    A novel fluorescence probe 1 based on triphenylamine was synthesized and characterized by NMR, IR, high resolution mass spectrometry and elemental analysis. Its fluorescence was quenched when pH below 2. There was a linear relationship between the fluorescence intensity and pH value ranged from 2 to 7. And its fluorescence emission was reversibility in acidic and alkaline solution. Furthermore, it exhibited remarkable selectivity and high sensitivity to Fe 3+ and was able to detect Fe 3+ in aqueous solution with low detection limit of 0.511 μM. Job plot showed that the binding stoichiometry of 1 with Fe 3+ was 1:1. Further observations of 1 H NMR titration suggested that coordination interaction between Fe 3+ and nitrogen atom on C =N bond promoted the intramolecular charge transfer (ICT) or energy transfer process causing fluorescence quenching. Additionally, 1 was also able to be applied for detecting Fe 3+ in living cell and bioimaging. - Graphical abstract: Triphenylamine based fluorescence probe can detect pH and Fe 3+ simultaneously in aqueous solution and be applied for detecting Fe 3+ in living cell and bioimaging. - Highlights: • The fluorescence probe is sensitive to pH in strong acid conditions. • The fluorescence chemosensor can detect pH and Fe 3+ simultaneously. • The recognition is able to carry out in aqueous solution. • The probe can also be applied for detecting Fe 3+ in living cell and bioimaging. • The sensor is synthesized easily with one step.

  20. Molecularly Imprinted Core-Shell CdSe@SiO2/CDs as a Ratiometric Fluorescent Probe for 4-Nitrophenol Sensing

    Science.gov (United States)

    Liu, Mingyue; Gao, Zhao; Yu, Yanjun; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2018-01-01

    4-Nitrophenol (4-NP) is a priority pollutant in water and is both carcinogenic and genotoxic to humans and wildlife even at very low concentrations. Thus, we herein fabricated a novel molecularly imprinted core-shell nanohybrid as a ratiometric fluorescent sensor for the highly sensitive and selective detection of 4-NP. This sensor was functioned by the transfer of fluorescence resonance energy between photoluminescent carbon dots (CDs) and 4-NP. This sensor was synthesized by linking organosilane-functionalized CDs to silica-coated CdSe quantum dots (CdSe@SiO2) via Si-O bonds. The nanohybrids were further modified by anchoring a molecularly imprinted polymer (MIP) layer on the ratiometric fluorescent sensor through a facile sol-gel polymerization method. The morphology, chemical structure, and optical properties of the resulting molecularly imprinted dual-emission fluorescent probe were characterized by transmission electron microscopy and spectroscopic analysis. The probe was then applied in the detection of 4-NP and exhibited good linearity between 0.051 and 13.7 μg/mL, in addition to a low detection limit of 0.026 μg/mL. Furthermore, the simplicity, reliability, high selectivity, and high sensitivity of the developed sensor demonstrate that the combination of MIPs and ratiometric fluorescence allows the preparation of excellent fluorescent sensors for the detection of trace or ultra-trace analytes.

  1. Novel DNA sequence detection method based on fluorescence energy transfer

    International Nuclear Information System (INIS)

    Kobayashi, S.; Tamiya, E.; Karube, I.

    1987-01-01

    Recently the detection of specific DNA sequence, DNA analysis, has been becoming more important for diagnosis of viral genomes causing infections disease and human sequences related to inherited disorders. These methods typically involve electrophoresis, the immobilization of DNA on a solid support, hybridization to a complementary probe, the detection using labeled with /sup 32/P or nonisotopically with a biotin-avidin-enzyme system, and so on. These techniques are highly effective, but they are very time-consuming and expensive. A principle of fluorescene energy transfer is that the light energy from an excited donor (fluorophore) is transferred to an acceptor (fluorophore), if the acceptor exists in the vicinity of the donor and the excitation spectrum of donor overlaps the emission spectrum of acceptor. In this study, the fluorescence energy transfer was applied to the detection of specific DNA sequence using the hybridization method. The analyte, single-stranded DNA labeled with the donor fluorophore is hybridized to a probe DNA labeled with the acceptor. Because of the complementary DNA duplex formation, two fluorophores became to be closed to each other, and the fluorescence energy transfer was occurred

  2. Lanthanide-based fluorescent tracers in complex media

    International Nuclear Information System (INIS)

    Brichart, Thomas

    2014-01-01

    Tracers are objects allowing the determination of the position or the distribution of a product; tracers are currently used in a great variety of domains. Despite the fact that each field has it's own specifications, it is possible to find tracers in medicine (contrast agents), anti-counterfeiting or geological exploration. We have developed lanthanide complex tracers for oil field injection waters. Those tracers, derived from the DOTA, have been detected at concentration lower than 1 ppb, thanks to a simple and compact apparatus. This detection has been made possible by the use of time-resolved fluorescence spectroscopy, this technique allows us to get rid of the background noise created by the intrinsic fluorescence of oil residues that are present in production waters. We also demonstrated how we can, through a reverse microemulsion synthesis, encapsulate several different dyes inside a single nanoparticle composed of a gold core and a silica shell. We showed as well, how those particles can be used as smart tracers to gather data, such as temperature, pH, solvents, etc. inside the well. Finally the use of lanthanides and scale inhibitors properties allowed us to create a simple and fast dosing protocol of such scale inhibitors in injection waters. This dosage will then allow the quick adjustment of their concentration inside each well. (author) [fr

  3. As bases moleculares da hemofilia A

    Directory of Open Access Journals (Sweden)

    Simone Ferreira Pio

    2009-01-01

    Full Text Available As hemofilias são doenças hemorrágicas resultantes da deficiência de fator VIII (hemofilia A ou de fator IX (hemofilia B da coagulação, decorrentes de mutações nos genes que codificam os fatores VIII ou IX, respectivamente. A hemofilia A é mais frequente que a hemofilia B e acomete aproximadamente 1:10.000 nascimentos masculinos. A gravidade e frequência dos episódios hemorrágicos está relacionado ao nível residual de atividade de fator VIII presente no plasma e este relaciona-se ao tipo de mutação associada à doença. A clonagem do gene do fator VIII tornou possível o conhecimento das bases moleculares da hemofilia A, sendo hoje conhecidas mais de 1.000 mutações associadas à doença. O conhecimento das bases moleculares da hemofilia A permite uma melhor compreensão da relação genótipo-fenótipo da doença, tomada de condutas clínicas diferenciadas em casos de mutações associadas a um maior risco de desenvolvimento de inibidor, determinação da condição de portadora de hemofilia em mulheres relacionadas aos pacientes, implementação de programa de aconselhamento genético/orientação familiar e melhor compreensão das relações estruturais-funcionais do gene-proteína. Este artigo propõe revisar as bases moleculares da hemofilia A, os métodos laboratoriais utilizados para a caracterização das mutações e as implicações clínicas envolvidas no diagnóstico molecular da hemofilia A.Hemophilias are bleeding disorders due to deficiency of the blood coagulation factor VIII (hemophilia A or factor IX (hemophilia B, resulting from mutation on the gene coding for factor VIII or factor IX. Hemophilia A is more frequent than hemophilia B and affects 1:10,000 male newborns. The severity and frequency of hemorrhagic episodes is related to residual activity of factor VIII present in the plasma and relates to the type of mutation associated with the disorder. Cloning of the factor VIII gene has enabled researchers to

  4. High-contrast fluorescence imaging based on the polarization dependence of the fluorescence enhancement using an optical interference mirror slide.

    Science.gov (United States)

    Yasuda, Mitsuru; Akimoto, Takuo

    2015-01-01

    High-contrast fluorescence imaging using an optical interference mirror (OIM) slide that enhances the fluorescence from a fluorophore located on top of the OIM surface is reported. To enhance the fluorescence and reduce the background light of the OIM, transverse-electric-polarized excitation light was used as incident light, and the transverse-magnetic-polarized fluorescence signal was detected. As a result, an approximate 100-fold improvement in the signal-to-noise ratio was achieved through a 13-fold enhancement of the fluorescence signal and an 8-fold reduction of the background light.

  5. Organic-based molecular switches for molecular electronics.

    Science.gov (United States)

    Fuentes, Noelia; Martín-Lasanta, Ana; Alvarez de Cienfuegos, Luis; Ribagorda, Maria; Parra, Andres; Cuerva, Juan M

    2011-10-05

    In a general sense, molecular electronics (ME) is the branch of nanotechnology which studies the application of molecular building blocks for the fabrication of electronic components. Among the different types of molecules, organic compounds have been revealed as promising candidates for ME, due to the easy access, great structural diversity and suitable electronic and mechanical properties. Thanks to these useful capabilities, organic molecules have been used to emulate electronic devices at the nanoscopic scale. In this feature article, we present the diverse strategies used to develop organic switches towards ME with special attention to non-volatile systems.

  6. "Plug and play" logic gates based on fluorescence switching regulated by self-assembly of nucleotide and lanthanide ions.

    Science.gov (United States)

    Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2014-06-25

    Molecular logic gates in response to chemical, biological, or optical input signals at a molecular level have received much interest over the past decade. Herein, we construct "plug and play" logic systems based on the fluorescence switching of guest molecules confined in coordination polymer nanoparticles generated from nucleotide and lanthanide ions. In the system, the addition of new modules directly enables new logic functions. PASS 0, YES, PASS 1, NOT, IMP, OR, and AND gates are successfully constructed in sequence. Moreover, different logic gates (AND, INH, and IMP) can be constructed using different guest molecules and the same input combinations. The work will be beneficial to the future logic design and expand the applications of coordination polymers.

  7. Use of fluorescence spectroscopy to measure molecular autofluorescence in diabetic subjects

    International Nuclear Information System (INIS)

    Gomes, Cinthia Zanini

    2011-01-01

    Diabetes Mellitus (DM) comprises a complex metabolic syndrome, caused by reduced or absent secretion of insulin by pancreatic beta cells, leading to hyperglycemia. Hyperglycemia promotes glycation of proteins and, consequently, the appearance of advanced glycation end products (AGEs). Currently, diabetic patients are monitored by determining levels of glucose and glycated hemoglobin (HbA1c). The complications caused by hyperglycemia may be divided into micro and macrovascular complications, represented by retinopathy, nephropathy, neuropathy and cardiovascular disease. Albumin (HSA) is the most abundant serum protein in the human body and is subject to glycation. The Protoporphyrin IX (PpIX) is the precursor molecule of heme synthesis, structural component of hemoglobin. The in vitro and animals studies have indicated that hyperglycemia promotes a decrease in its concentration in erythrocytes. The fluorescence spectroscopy is a technique widely used in biomedical field. The autofluorescence corresponds to the intrinsic fluorescence present in some molecules, this being associated with the same structure. The aim of this study was to use fluorescence spectroscopy to measure levels of erythrocyte PpIX autofluorescence and AGE-HSA in diabetic and healthy subjects and compare them with levels of blood glucose and HbA1c. This study was conducted with 151 subjects (58 controls and 93 diabetics). Epidemiological data of patients and controls were obtained from medical records. For control subjects, blood glucose levels were obtained from medical records and levels of Hb1Ac obtained by using commercial kits. The determination of the PpIX autofluorescence was performed with excitation at 405 nm and emission at 632 nm. Determination of AGE-HSA was performed with excitation at 370 nm and emission at 455 nm. Approximately 50% of diabetic had micro and macrovascular lesions resulting from hyperglycemia. There were no significant differences in the PpIX emission intensity values

  8. Turn-on fluorescent chemosensor for Hg2+ based on multivalent rhodamine ligands

    NARCIS (Netherlands)

    Wang, X.; Iqbal, M.; Huskens, Jurriaan; Verboom, Willem

    2012-01-01

    Rhodamine-based fluorescent chemosensors 1 and 2 exhibit selective fluorescence enhancement to Fe3+ and Hg2+ over other metal ions at 580 nm in CH3CN/H2O (3/1, v/v) solution. Bis(rhodamine) chemosensor 1, under optimized conditions (CH3CN/HEPES buffer (0.02 M, pH = 7.0) (95/5, v/v)), shows a high

  9. An image fiber based fluorescent probe with associated signal processing scheme for biomedical diagnostics

    International Nuclear Information System (INIS)

    Vaishakh, M; Murukeshan, V M; Seah, L K

    2008-01-01

    A dual-modality image fiber based fluorescent probe that can be used for depth sensitive imaging and suppression of fluorescent emissions with nanosecond lifetime difference is proposed and illustrated in this paper. The system can give high optical sectioning and employs an algorithm for obtaining phase sensitive images. The system can find main application in in vivo biomedical diagnostics for detecting biochemical changes for distinguishing malignant tissue from healthy tissue

  10. A chromenoquinoline-based fluorescent off-on thiol probe for bioimaging.

    Science.gov (United States)

    Kand, Dnyaneshwar; Kalle, Arunasree Marasanapalli; Varma, Sreejith Jayasree; Talukdar, Pinaki

    2012-03-11

    A new chromenoquinoline-based fluorescent off-on thiol probe 2 is reported. In aqueous buffer solutions at physiological pH, the probe exhibited 223-fold enhancement in fluorescence intensity by a Michael addition of cysteine to the maleimide appended to a chromenoquinoline. Cell permeability and live cell imaging of thiols are also demonstrated. This journal is © The Royal Society of Chemistry 2012

  11. Fluorescence-based characterization of genetically encoded peptides that fold in live cells: progress toward a generic hairpin scaffold

    Science.gov (United States)

    Cheng, Zihao; Campbell, Robert E.

    2007-02-01

    Binding proteins suitable for expression and high affinity molecular recognition in the cytoplasm or nucleus of live cells have numerous applications in the biological sciences. In an effort to add a new minimal motif to the growing repertoire of validated non-immunoglobulin binding proteins, we have undertaken the development of a generic protein scaffold based on a single β-hairpin that can fold efficiently in the cytoplasm. We have developed a method, based on the measurement of fluorescence resonance energy transfer (FRET) between a genetically fused cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP), that allows the structural stability of recombinant β-hairpin peptides to be rapidly assessed both in vitro and in vivo. We have previously reported the validation of this method when applied to a 16mer tryptophan zipper β-hairpin. We now describe the use of this method to evaluate the potential of a designed 20mer β-hairpin peptide with a 3rd Trp/Trp cross-strand pair to function as a generic protein scaffold. Quantitative analysis of the FRET efficiency, resistance to proteolysis (assayed by loss of FRET), and circular dichroism spectra revealed that the 20mer peptide is significantly more tolerant of destabilizing mutations than the 16mer peptide. Furthermore, we experimentally demonstrate that the in vitro determined β-hairpin stabilities are well correlated with in vivo β-hairpin stabilities as determined by FRET measurements of colonies of live bacteria expressing the recombinant peptides flanked by CFP and YFP. Finally, we report on our progress to develop highly folded 24mer and 28mer β-hairpin peptides through the use of fluorescence-based library screening.

  12. A chemosensor showing discriminating fluorescent response for highly selective and nanomolar detection of Cu²⁺ and Zn²⁺ and its application in molecular logic gate.

    Science.gov (United States)

    Fegade, Umesh A; Sahoo, Suban K; Singh, Amanpreet; Singh, Narinder; Attarde, Sanjay B; Kuwar, Anil S

    2015-05-04

    A fluorescent based receptor (4Z)-4-(4-diethylamino)-2-hydroxybenzylidene amino)-1,2dihydro-1,5-dimethyl-2-phenylpyrazol-3-one (receptor 3) was developed for the highly selective and sensitive detection of Cu(2+) and Zn(2+) in semi-aqueous system. The fluorescence of receptor 3 was enhanced and quenched, respectively, with the addition of Zn(2+) and Cu(2+) ions over other surveyed cations. The receptor formed host-guest complexes in 1:1 stoichiometry with the detection limit of 5 nM and 15 nM for Cu(2+) and Zn(2+) ions, respectively. Further, we have effectively utilized the two metal ions (Cu(2+) and Zn(2+)) as chemical inputs for the manufacture of INHIBIT type logic gate at molecular level using the fluorescence responses of receptor 3 at 450 nm. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Oral cancer detection based on fluorescence polarization of blood plasma at excitation wavelength 405 nm

    Science.gov (United States)

    Pachaiappan, Rekha; Prakasarao, Aruna; Manoharan, Yuvaraj; Dornadula, Koteeswaran; Singaravelu, Ganesan

    2017-02-01

    During metabolism the metabolites such as hormones, proteins and enzymes were released in to the blood stream by the cells. These metabolites reflect any change that occurs due to any disturbances in normal metabolic function of the human system. This was well observed with the altered spectral signatures observed with fluorescence spectroscopic technique. Previously many have reported on the significance of native fluorescence spectroscopic method in the diagnosis of cancer. As fluorescence spectroscopy is sensitive and simple, it has complementary techniques such as excitation-emission matrix, synchronous and polarization. The fluorescence polarization measurement provides details about any association or binding reactions and denaturing effects that occurs due to change in the micro environment of cells and tissues. In this study, we have made an attempt in the diagnosis of oral cancer at 405 nm excitation using fluorescence polarization measurement. The fluorescence anisotropic values calculated from polarized fluorescence spectral data of normal and oral cancer subjects yielded a good accuracy when analyzed with linear discriminant analysis based artificial neural network. The results will be discussed in detail.

  14. Homogeneous non-competitive bioaffinity assay based on fluorescence resonance energy transfer

    International Nuclear Information System (INIS)

    Kokko, Tiina; Kokko, Leena; Soukka, Tero; Loevgren, Timo

    2007-01-01

    A homogeneous non-competitive assay principle for measurement of small analytes based on quenching of fluorescence is described. Fluorescence resonance energy transfer (FRET) occurs between the donor, intrinsically fluorescent europium(III)-chelate conjugated to streptavidin, and the acceptor, quencher dye conjugated to biotin derivative when the biotin-quencher is bound to Eu-streptavidin. Fluorescence can be measured only from those streptavidins that are bound to biotin of the sample, while the fluorescence of the streptavidins that are not occupied by biotin are quenched by quencher-biotin conjugates. The quenching efficiencies of the non-fluorescent quencher dyes were over 95% and one dye molecule was able to quench the fluorescence of more than one europium(III)-chelate. This, however, together with the quadrovalent nature of streptavidin limited the measurable range of the assay to 0.2-2 nmol L -1 . In this study we demonstrated that FRET could be used to design a non-competitive homogeneous assay for a small analyte resulting in equal performance with competitive heterogeneous assay

  15. Effects of alcohols on fluorescence intensity and color of a discharged-obelin-based biomarker.

    Science.gov (United States)

    Alieva, Roza R; Belogurova, Nadezhda V; Petrova, Alena S; Kudryasheva, Nadezhda S

    2014-05-01

    Photoproteins are responsible for bioluminescence of marine coelenterates; bioluminescent and fluorescent biomarkers based on photoproteins are useful for monitoring of calcium-dependent processes in medical investigations. Here, we present the analysis of intensity and color of light-induced fluorescence of Ca(2+)-discharged photoprotein obelin in the presence of alcohols (ethanol and glycerol). Complex obelin spectra obtained at different concentrations of the alcohols at 350- and 280-nm excitation (corresponding to polypeptide-bound coelenteramide and tryptophan absorption regions) were deconvoluted into Gaussian components; fluorescent intensity and contributions of the components to experimental spectra were analyzed. Five Gaussian components were found in different spectral regions-ultraviolet (tryptophan emission), blue-green (coelenteramide emission), and red (hypothetical indole-coelenteramide exciplex emission). Inhibition coefficients and contributions of the components to experimental fluorescent spectra showed that presence of alcohols increased contributions of ultraviolet, violet, and red components, but decreased contributions of components in the blue-green region. The effects were related to (1) changes of proton transfer efficiency in fluorescent S*1 state of coelenteramide in the obelin active center and (2) formation of indole-coelenteramide exciplex at 280-nm photoexcitation. The data show that variation of fluorescence color and intensity in the presence of alcohols and dependence of emission spectra on excitation wavelength should be considered while applying the discharged obelin as a fluorescence biomarker.

  16. Highly selective rhodamine-based fluorescence turn-on chemosensor for Al3+ ion

    Science.gov (United States)

    Manjunath, Rangasamy; Kannan, Palaninathan

    2018-05-01

    A new rhodamine-based colorimetric and fluorescent turn-on chemosensor (L) has been designed and synthesized for selective and sensitive detection of Al3+ ion. The sensing behavior toward metal ion was investigated by UV/Vis and fluorescence spectroscopy. Upon addition of Al3+ ion to solution of L provided a visual color change as well as significantly fluorescent enhancement, while other metal ions including Na+, Mg2+, K+, Mn2+, Fe3+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+ and Hg2+ ions fails to generate a distinct color and spectral changes, the distinct color change and rapid switch-on fluorescence also provide naked eye detection for Al3+ ion. The mechanism involved equilibrium between non-fluorescent spirocyclic form and highly fluorescent ring open form process was utilized and 1:2 stoichiometry for L-Al3+ complex formed with an association constant of 1.42 × 103 M-1. Moreover, chemosensor L was applied for living cell imaging and confirmed that can be used as a fluorescent probe for monitoring Al3+ ion in living cells.

  17. Feasibility of Raman spectroscopy in vitro after 5-ALA-based fluorescence diagnosis in the bladder

    Science.gov (United States)

    Grimbergen, M. C. M.; van Swol, C. F. P.; van Moorselaar, R. J. A.; Mahadevan-Jansen, A.,; Stone, N.

    2006-02-01

    Photodynamic diagnosis (PDD) has become popular in bladder cancer detection. Several studies have however shown an increased false positive biopsies rate under PDD guidance compared to conventional cystoscopy. Raman spectroscopy is an optical technique that utilizes molecular specific, inelastic scattering of light photons to interrogate biological tissues, which can successfully differentiate epithelial neoplasia from normal tissue and inflammations in vitro. This investigation was performed to show the feasibility of NIR Raman spectroscopy in vitro on biopsies obtained under guidance of 5-ALA induced PPIX fluorescence imaging. Raman spectra of a PPIX solution was measured to obtain a characteristic signature for the photosensitzer without contributions from tissue constituents. Biopsies were obtained from patients with known bladder cancer instilled with 50ml, 5mg 5-ALA two hours prior to trans-urethral resection of tumor (TURT). Additional biopsies were obtained at a fluorescent and non-fluorescent area, snap-frozen in liquid nitrogen and stored at -80 °C. Each biopsy was thawed before measurements (10sec integration time) with a confocal Raman system (Renishaw Gloucestershire, UK). The 830 nm excitation (300mW) source is focused on the tissue by a 20X ultra-long-working-distance objective. Differences in fluorescence background between the two groups were removed by means of a special developed fluorescence subtraction algorithm. Raman spectra from ALA biopsies showed different fluorescence background which can be effectively removed by a fluorescence subtraction algorithm. This investigation shows that the interaction of the ALA induced PPIX with Raman spectroscopy in bladder samples. Combination of these techniques in-vivo may lead to a viable method of optical biopsies in bladder cancer detection.

  18. Pentamethinium fluorescent probes: The impact of molecular structure on photophysical properties and subcellular localization

    Czech Academy of Sciences Publication Activity Database

    Bříza, T.; Rimpelová, S.; Králová, Jarmila; Záruba, K.; Kejík, Z.; Ruml, T.; Martásek, P.; Král, V.

    2014-01-01

    Roč. 107, August 2014 (2014), s. 51-59 ISSN 0143-7208 R&D Projects: GA AV ČR KAN200100801; GA ČR(CZ) GAP303/11/1291; GA MŠk(CZ) CZ.01.05/2.1.00/01.00.30; GA MŠk(CZ) CZ.1.07/2.300/30.0060 Institutional support: RVO:68378050 Keywords : Pentamethinium salts * Fluorescent probes * Mitochondria * Cardiolipin Photostability * Organelle imaging Subject RIV: CE - Biochemistry Impact factor: 3.966, year: 2014

  19. Molecular fluorescence enhancement in plasmonic environments: exploring the role of nonlocal effects

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Stefanou, Nikolaos; Wubs, Martijn

    2016-01-01

    in the nanoparticle vicinity. Here we explore the influence of hitherto disregarded nonclassical effects in the description of emitter-plasmon hybrids, focusing on the roles of metal nonlocal response and especially size-dependent plasmon damping. Through extensive modelling of metallic nanospheres and nanoshells...... a more complete physical description combining electron convection and diffusion, we show that not only are fluorescence rates dramatically reduced as compared to the predictions of the local description and the common hydrodynamic Drude model, but the optimum emitter-nanoparticle distance is also...

  20. Synchronous fluorescence based biosensor for albumin determination by cooperative binding of fluorescence probe in a supra-biomolecular host-protein assembly.

    Science.gov (United States)

    Patra, Digambara

    2010-01-15

    A synchronous fluorescence probe based biosensor for estimation of albumin with high sensitivity and selectivity was developed. Unlike conventional fluorescence emission or excitation spectral measurements, synchronous fluorescence measurement offered exclusively a new synchronous fluorescence peak in the shorter wavelength range upon binding of chrysene with protein making it an easy identification tool for albumin determination. The cooperative binding of a fluorescence probe, chrysene, in a supramolecular host-protein assembly during various albumin assessments was investigated. The presence of supramolecular host molecules such as beta-cyclodextrin, curucurbit[6]uril or curucurbit[7]uril have little influence on sensitivity or limit of detection during albumin determination but reduced dramatically interference from various coexisting metal ion quenchers/enhancers. Using the present method the limit of detection for BSA and gamma-Globulin was found to be 0.005 microM which is more sensitive than reported values. Copyright 2009 Elsevier B.V. All rights reserved.

  1. A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution

    Science.gov (United States)

    Zhou, Yanmei; Zhou, Hua; Ma, Tongsen; Zhang, Junli; Niu, Jingyang

    2012-03-01

    A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag+ over other metal ions such as Pb2+, Na+, K+, Cd2+, Ba2+, Cr3+, Zn2+, Cu2+, Ni2+, Ca2+, Al3+ and Mg2+ in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag+ ion. The fluorescence intensity quenched with increasing the concentration of Ag+ at 682 nm. The method of job's plot confirmed the 1:2 complex between Ag+ and probe, and the mechanism was proposed.

  2. Advanced molecular devices based on light-driven molecular motors

    NARCIS (Netherlands)

    Chen, Jiawen

    2015-01-01

    Nature has provided a large collection of molecular machines and devices that are among the most amazing nanostructures on this planet. These machines are able to operate complex biological processes which are of great importance in our organisms. Inspired by these natural devices, artificial

  3. An aptamer-based fluorescence bio-sensor for chiral recognition of arginine enantiomers.

    Science.gov (United States)

    Yuan, Haiyan; Huang, Yunmei; Yang, Jidong; Guo, Yuan; Zeng, Xiaoqing; Zhou, Shang; Cheng, Jiawei; Zhang, Yuhui

    2018-07-05

    In this study, a novel aptamer - based fluorescence bio-sensor (aptamer-AuNps) was developed for chiral recognition of arginine (Arg) enantiomers based on aptamer and gold nanoparticles (AuNps). Carboxyfluorescein (FAM) labeled aptamers (Apt) were absorbed on AuNps and their fluorescence intensity could be significantly quenched by AuNps based on fluorescence resonance energy transfer (FRET). Once d-Arg or l-Arg were added into the above solution, the aptamer specifically bind to Arg enantiomers and released from AuNps, so the fluorescence intensity of d-Arg system and l-Arg system were all enhanced. The affinity of Apt to l-Arg is tighter to d-Arg, so the enhanced fluorescence signals of l-Arg system was stronger than d-Arg system. What's more, the enhanced fluorescence were directly proportional to the concentration of d-Arg and l-Arg ranging from 0-300 nM and 0-400 nM with related coefficients of 0.9939 and 0.9952, respectively. Furthermore, the method was successfully applied to detection l-Arg in human urine samples with satisfactory results. Eventually, a simple "OR" logic gate with d-Arg &l-Arg as inputs and AuNps aggregation state as outputs was fabricated, which can help us understand the chiral recognition process deeply. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yi [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China); Huang, Xiaolin [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Yu, Ruijin [College of Science, Northwest A& F University, Yangling, Shaanxi 712100 (China); Zhou, Yaofeng [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Xiong, Yonghua, E-mail: yhxiongchen@163.com [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China)

    2016-09-14

    The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H{sub 2}O{sub 2}) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H{sub 2}O{sub 2} or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL{sup −1} to 625 pg mL{sup −1} with a limit of detection of 2.2 pg mL{sup −1}, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H{sub 2}O{sub 2}-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

  5. Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

    International Nuclear Information System (INIS)

    Liang, Yi; Huang, Xiaolin; Yu, Ruijin; Zhou, Yaofeng; Xiong, Yonghua

    2016-01-01

    The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H_2O_2) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H_2O_2 or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL"−"1 to 625 pg mL"−"1 with a limit of detection of 2.2 pg mL"−"1, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H_2O_2-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

  6. Tuning Selectivity of Fluorescent Carbon Nanotube-Based Neurotransmitter Sensors.

    Science.gov (United States)

    Mann, Florian A; Herrmann, Niklas; Meyer, Daniel; Kruss, Sebastian

    2017-06-28

    Detection of neurotransmitters is an analytical challenge and essential to understand neuronal networks in the brain and associated diseases. However, most methods do not provide sufficient spatial, temporal, or chemical resolution. Near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have been used as building blocks for sensors/probes that detect catecholamine neurotransmitters, including dopamine. This approach provides a high spatial and temporal resolution, but it is not understood if these sensors are able to distinguish dopamine from similar catecholamine neurotransmitters, such as epinephrine or norepinephrine. In this work, the organic phase (DNA sequence) around SWCNTs was varied to create sensors with different selectivity and sensitivity for catecholamine neurotransmitters. Most DNA-functionalized SWCNTs responded to catecholamine neurotransmitters, but both dissociation constants ( K d ) and limits of detection were highly dependent on functionalization (sequence). K d values span a range of 2.3 nM (SWCNT-(GC) 15 + norepinephrine) to 9.4 μM (SWCNT-(AT) 15 + dopamine) and limits of detection are mostly in the single-digit nM regime. Additionally, sensors of different SWCNT chirality show different fluorescence increases. Moreover, certain sensors (e.g., SWCNT-(GT) 10 ) distinguish between different catecholamines, such as dopamine and norepinephrine at low concentrations (50 nM). These results show that SWCNTs functionalized with certain DNA sequences are able to discriminate between catecholamine neurotransmitters or to detect them in the presence of interfering substances of similar structure. Such sensors will be useful to measure and study neurotransmitter signaling in complex biological settings.

  7. Fluorescent nanocellulosic hydrogels based on graphene quantum dots for sensing laccase

    International Nuclear Information System (INIS)

    Ruiz-Palomero, Celia; Benítez-Martínez, Sandra; Soriano, M. Laura; Valcárcel, Miguel

    2017-01-01

    A novel low-cost fluorimetric platform based on sulfur, nitrogen-codoped graphene quantum dots immersed into nanocellulosic hydrogels is designed and applied in detecting the laccase enzyme. Although most of methods for detecting laccase are based on their catalytic activity, which is strongly dependent on environmental parameters, we report a sensitive and selective method based on the fluorescence response of hydrogels containing graphene quantum dots (GQDs) acting as luminophore towards laccase. The easily-prepared gel matrix not only improves the fluorescence signal of GQDs by avoiding their self-quenching but also stabilizes their fluorescence signal and improves their sensitivity towards laccase. Noncovalent interactions between the sensor and the analyte are believed to be causing this significant quenching without peak-shifts of GQD fluorescence via energy transfer. The selective extraction of laccase was proved in different shampoos as complex matrices achieving a detection limit of 0.048 U mL −1 and recoveries of 86.2–94.1%. As the unusual properties of nanocellulose and GQDs, the fluorescent sensor is simple, eco-friendly and cost-efficient. This straightforward strategy is able to detect and stabilize laccase, being an added-value for storage and recycling enzymes. - Highlights: • Fluorescent hydrogels were constructed by combining nanocellulose and graphene quantum dots. • The resulting hydrogels exhibited fluorescence quenching in presence of laccase. • Equilibrium in the optical signal of S,N-graphene quantum dots in presence of laccase was achieved faster within hydrogels. • The proposed method to determine laccase using fluorescent hydrogels was successfully applied in shampoo.

  8. Quantifying the Assembly of Multicomponent Molecular Machines by Single-Molecule Total Internal Reflection Fluorescence Microscopy.

    Science.gov (United States)

    Boehm, E M; Subramanyam, S; Ghoneim, M; Washington, M Todd; Spies, M

    2016-01-01

    Large, dynamic macromolecular complexes play essential roles in many cellular processes. Knowing how the components of these complexes associate with one another and undergo structural rearrangements is critical to understanding how they function. Single-molecule total internal reflection fluorescence (TIRF) microscopy is a powerful approach for addressing these fundamental issues. In this article, we first discuss single-molecule TIRF microscopes and strategies to immobilize and fluorescently label macromolecules. We then review the use of single-molecule TIRF microscopy to study the formation of binary macromolecular complexes using one-color imaging and inhibitors. We conclude with a discussion of the use of TIRF microscopy to examine the formation of higher-order (i.e., ternary) complexes using multicolor setups. The focus throughout this article is on experimental design, controls, data acquisition, and data analysis. We hope that single-molecule TIRF microscopy, which has largely been the province of specialists, will soon become as common in the tool box of biophysicists and biochemists as structural approaches have become today. © 2016 Elsevier Inc. All rights reserved.

  9. A ditopic fluorescence sensor for saccharides and mercury based on a boronic-acid receptor and desulfurisation reaction.

    Science.gov (United States)

    Xing, Zhitao; Wang, Hui-Chen; Cheng, Yixiang; James, Tony D; Zhu, Chengjian

    2011-11-04

    Two boron-contained fluorescent sensors, 1 and 2, based on coumarin have been prepared. The fluorescence response of the two systems was investigated with addition of saccharide and mercury ions. Sensor 2 behaves as a bifunctional fluorescent switch with chemical inputs of D-fructose and mercury ions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Surface based detection schemes for molecular interferometry experiments - implications and possible applications

    Science.gov (United States)

    Juffmann, Thomas; Milic, Adriana; Muellneritsch, Michael; Arndt, Markus

    2011-03-01

    Surface based detection schemes for molecular interferometry experiments might be crucial in the search for the quantum properties of larger and larger objects since they provide single particle sensitivity. Here we report on molecular interferograms of different biomolecules imaged using fluorescence microscopy. Being able to watch the build-up of an interferogram live and in situ reveals the matter-wave behavior of these complex molecules in an unprecedented way. We examine several problems encountered due to van-der-Waals forces between the molecules and the diffraction grating and discuss possible ways to circumvent these. Especially the advent of ultra-thin (1-100 atomic layers) diffraction masks might path the way towards molecular holography. We also discuss other possible applications such as coherent molecular microscopy.

  11. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Uzun, Lokman; Uzek, Recep; Şenel, Serap; Say, Ridvan; Denizli, Adil

    2013-01-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Highlights: • Lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles • Direct incorporation of the fluorescent complex into polymeric backbone. • Imprinting by assistance of cupric ion coordination into nanoparticles • Evaluation of the chiral biorecognition ability of nanoparticles • Simultaneous selective separation and fluorescent monitoring

  12. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Uzun, Lokman, E-mail: lokman@hacettepe.edu.tr [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey); Uzek, Recep; Şenel, Serap [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey); Say, Ridvan [Anadolu University, Department of Chemistry, 26470, Eskisehir (Turkey); Denizli, Adil [Hacettepe University, Department of Chemistry, 06381, Ankara (Turkey)

    2013-08-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Highlights: • Lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles • Direct incorporation of the fluorescent complex into polymeric backbone. • Imprinting by assistance of cupric ion coordination into nanoparticles • Evaluation of the chiral biorecognition ability of nanoparticles • Simultaneous selective separation and fluorescent monitoring.

  13. Efficient and Scalable Synthesis of 4-Carboxy-Pennsylvania Green Methyl Ester: A Hydrophobic Building Block for Fluorescent Molecular Probes.

    Science.gov (United States)

    Woydziak, Zachary R; Fu, Liqiang; Peterson, Blake R

    2014-01-01

    Fluorinated fluorophores are valuable tools for studies of biological systems. However, amine-reactive single-isomer derivatives of these compounds are often very expensive. To provide an inexpensive alternative, we report a practical synthesis of 4-carboxy-Pennsylvania Green methyl ester. Derivatives of this hydrophobic fluorinated fluorophore, a hybrid of the dyes Oregon Green and Tokyo Green, are often cell permeable, enabling labeling of intracellular targets and components. Moreover, the low pKa of Pennsylvania Green (4.8) confers bright fluorescence in acidic cellular compartments such as endosomes, enhancing its utility for chemical biology investigations. To improve access to the key intermediate 2,7-difluoro-3,6-dihydroxyxanthen-9-one, we subjected bis-(2,4,5-trifluorophenyl)methanone to iterative nucleophilic aromatic substitution by hydroxide on scales of > 40 g. This intermediate was used to prepare over 15 grams of pure 4-carboxy-Pennsylvania Green methyl ester in 28% overall yield without requiring chromatography. This compound can be converted into the amine reactive N -hydroxysuccinimidyl ester in essentially quantitative yield for the synthesis of a wide variety of fluorescent molecular probes.

  14. Evaluating the binding efficiency of pheromone binding protein with its natural ligand using molecular docking and fluorescence analysis

    Science.gov (United States)

    Ilayaraja, Renganathan; Rajkumar, Ramalingam; Rajesh, Durairaj; Muralidharan, Arumugam Ramachandran; Padmanabhan, Parasuraman; Archunan, Govindaraju

    2014-06-01

    Chemosignals play a crucial role in social and sexual communication among inter- and intra-species. Chemical cues are bound with protein that is present in the pheromones irrespective of sex are commonly called as pheromone binding protein (PBP). In rats, the pheromone compounds are bound with low molecular lipocalin protein α2u-globulin (α2u). We reported farnesol is a natural endogenous ligand (compound) present in rat preputial gland as a bound volatile compound. In the present study, an attempt has been made through computational method to evaluating the binding efficiency of α2u with the natural ligand (farnesol) and standard fluorescent molecule (2-naphthol). The docking analysis revealed that the binding energy of farnesol and 2-naphthol was almost equal and likely to share some binding pocket of protein. Further, to extrapolate the results generated through computational approach, the α2u protein was purified and subjected to fluorescence titration and binding assay. The results showed that the farnesol is replaced by 2-naphthol with high hydrophobicity of TYR120 in binding sites of α2u providing an acceptable dissociation constant indicating the binding efficiency of α2u. The obtained results are in corroboration with the data made through computational approach.

  15. Molecular basis of photochromism of a fluorescent protein revealed by direct 13C detection under laser illumination

    International Nuclear Information System (INIS)

    Mizuno, Hideaki; Mal, Tapas Kumar; Waelchli, Markus; Fukano, Takashi; Ikura, Mitsuhiko; Miyawaki, Atsushi

    2010-01-01

    Dronpa is a green fluorescent protein homologue with a photochromic property. A green laser illumination reversibly converts Dronpa from a green-emissive bright state to a non-emissive dark state, and ultraviolet illumination converts it to the bright state. We have employed solution NMR to understand the underlying molecular mechanism of the photochromism. The detail characterization of Dronpa is hindered as it is metastable in the dark state and spontaneously converts to the bright state. To circumvent this issue, we have designed in magnet laser illumination device. By combining the device with a 150-mW argon laser at 514.5 nm, we have successfully converted and maintained Dronpa in the dark state in the NMR tube by continuous illumination during the NMR experiments. We have employed direct-detection of 13 C nuclei from the carbon skeleton of the chromophore for detailed characterization of chromophore in both states of Dronpa by using the Bruker TCI cryoprobe. The results from NMR data have provided direct evidence of the double bond formation between C α and C β of Y63 in the chromophore, the β-barrel structure in solution, and the ionized and protonated state of Y63 hydroxyl group in the bright and dark states, respectively. These studies have also revealed that a part of β-barrel around the chromophore becomes polymorphic only in the dark state, which may be critical to make the fluorescence dim by increasing the contribution of non-emissive vibrational relaxation pathways.

  16. Semiconductor quantum dots as fluorescent probes for in vitro and in vivo bio-molecular and cellular imaging

    Directory of Open Access Journals (Sweden)

    Sarwat B. Rizvi

    2010-08-01

    Full Text Available Over the years, biological imaging has seen many advances, allowing scientists to unfold many of the mysteries surrounding biological processes. The ideal imaging resolution would be in nanometres, as most biological processes occur at this scale. Nanotechnology has made this possible with functionalised nanoparticles that can bind to specific targets and trace processes at the cellular and molecular level. Quantum dots (QDs or semiconductor nanocrystals are luminescent particles that have the potential to be the next generation fluorophores. This paper is an overview of the basics of QDs and their role as fluorescent probes for various biological imaging applications. Their potential clinical applications and the limitations that need to be overcome have also been discussed.

  17. Compression of Born ratio for fluorescence molecular tomography/x-ray computed tomography hybrid imaging: methodology and in vivo validation.

    Science.gov (United States)

    Mohajerani, Pouyan; Ntziachristos, Vasilis

    2013-07-01

    The 360° rotation geometry of the hybrid fluorescence molecular tomography/x-ray computed tomography modality allows for acquisition of very large datasets, which pose numerical limitations on the reconstruction. We propose a compression method that takes advantage of the correlation of the Born-normalized signal among sources in spatially formed clusters to reduce the size of system model. The proposed method has been validated using an ex vivo study and an in vivo study of a nude mouse with a subcutaneous 4T1 tumor, with and without inclusion of a priori anatomical information. Compression rates of up to two orders of magnitude with minimum distortion of reconstruction have been demonstrated, resulting in large reduction in weight matrix size and reconstruction time.

  18. Acridine-based fluorescence chemosensors for selective sensing of Fe3+ and Ni2+ ions

    Science.gov (United States)

    Wang, Chaoyu; Fu, Jiaxin; Yao, Kun; Xue, Kun; Xu, Kuoxi; Pang, Xiaobin

    2018-06-01

    Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13 μM and 1.52 μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Job's plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.

  19. Fluorescent pH sensor based on Ag@SiO2 core-shell nanoparticle.

    Science.gov (United States)

    Bai, Zhenhua; Chen, Rui; Si, Peng; Huang, Youju; Sun, Handong; Kim, Dong-Hwan

    2013-06-26

    We have demonstrated a novel method for the preparation of a fluorescence-based pH sensor by combining the plasmon resonance band of Ag core and pH sensitive dye (HPTS). A thickness-variable silica shell is placed between Ag core and HPTS dye to achieve the maximum fluorescence enhancement. At the shell thickness of 8 nm, the fluorescence intensity increases 4 and 9 times when the sensor is excited at 405 and 455 nm, respectively. At the same time, the fluorescence intensity shows a good sensitivity toward pH value in the range of 5-9, and the ratio of emission intensity at 513 nm excited at 455 nm to that excited at 405 nm versus the pH value in the range of 5-9 is determined. It is believed that the present pH sensor has the potential for determining pH real time in the biological sample.

  20. Structural and dynamical aspects of skin studied by multiphoton excitation fluorescence microscopy-based methods

    DEFF Research Database (Denmark)

    Bloksgaard, Maria; Brewer, Jonathan R.; Bagatolli, Luis

    2013-01-01

    ' parameters. Specifically, by applying these methods, spatially resolved maps of water dipolar relaxation (generalized polarization function using the 6-lauroyl-2-(N,N-dimethylamino)naphthale probe), activity of protons (fluorescence lifetime imaging using a proton sensitive fluorescence probe--2,7-bis-(2......-carboxyethyl)-5-(and-6)-carboxyfluorescein) and diffusion coefficients of distinct fluorescence probes (raster imaging correlation spectroscopy) can be obtained from different regions of the tissue. Comparative studies of different tissue strata, but also between equivalent regions of normal and abnormal......This mini-review reports on applications of particular multiphoton excitation microscopy-based methodologies employed in our laboratory to study skin. These approaches allow in-depth optical sectioning of the tissue, providing spatially resolved information on specific fluorescence probes...

  1. Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform.

    Science.gov (United States)

    Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

    2015-12-14

    Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.

  2. A ratiometric fluorescent quantum dots based biosensor for organophosphorus pesticides detection by inner-filter effect.

    Science.gov (United States)

    Yan, Xu; Li, Hongxia; Han, Xiaosong; Su, Xingguang

    2015-12-15

    In this work, we develop a novel and sensitive sensor for the detection of organophosphorus pesticides based on the inner-filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent quantum dots (RF-QDs). The RF-QDs has been designed by hybridizing two differently colored CdTe QDs, in which the red emissive QDs entrapped in the silica sphere acting as the reference signal, and the green emissive QDs covalently attached on the silica surface serving as the response signal.The fluorescence of RF-QDs could be quenched by AuNPs based on IFE. Protamine could effectively turn on the fluorescence due to the electrostatic attraction between protamine and AuNPs. Trypsin can easily hydrolyze protamine, leading to the quench of the fluorescence. Then, the fluorescence could be recovered again by the addition of parathion-methyl (PM) which could inhibit the activity of trypsin. By measuring the fluorescence of RF-QDs, the inhibition efficiency of PM to trypsin activity was evaluated. Under the optimized conditions, the inhibition efficiency was proportional to the logarithm of PM concentration in the range of 0.04-400 ng mL(-1), with a detection limit of 0.018 ng mL(-1). Furthermore, the simple and convenient method had been used for PM detection in environmental and agricultural samples with satisfactory results. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

    Science.gov (United States)

    Sharifzadeh, Mohsen; Bernstein, Paul S.; Gellermann, Werner

    2006-10-01

    We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue-green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils.

  4. Static Hyperspectral Fluorescence Imaging of Viscous Materials Based on a Linear Variable Filter Spectrometer

    Directory of Open Access Journals (Sweden)

    Alexander W. Koch

    2013-09-01

    Full Text Available This paper presents a low-cost hyperspectral measurement setup in a new application based on fluorescence detection in the visible (Vis wavelength range. The aim of the setup is to take hyperspectral fluorescence images of viscous materials. Based on these images, fluorescent and non-fluorescent impurities in the viscous materials can be detected. For the illumination of the measurement object, a narrow-band high-power light-emitting diode (LED with a center wavelength of 370 nm was used. The low-cost acquisition unit for the imaging consists of a linear variable filter (LVF and a complementary metal oxide semiconductor (CMOS 2D sensor array. The translucent wavelength range of the LVF is from 400 nm to 700 nm. For the confirmation of the concept, static measurements of fluorescent viscous materials with a non-fluorescent impurity have been performed and analyzed. With the presented setup, measurement surfaces in the micrometer range can be provided. The measureable minimum particle size of the impurities is in the nanometer range. The recording rate for the measurements depends on the exposure time of the used CMOS 2D sensor array and has been found to be in the microsecond range.

  5. Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform

    Science.gov (United States)

    Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

    2015-11-01

    Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (r

  6. Hypoxia-Targeting Fluorescent Nanobodies for Optical Molecular Imaging of Pre-Invasive Breast Cancer

    NARCIS (Netherlands)

    van Brussel, Aram S A; Adams, Arthur; Oliveira, Sabrina; Dorresteijn, Bram; El Khattabi, Mohamed; Vermeulen, J. F.; van der Wall, Elsken; Mali, Willem P Th M; Derksen, Patrick W B; van Diest, Paul J; van Bergen En Henegouwen, Paul M P

    PURPOSE: The aim of this work was to develop a CAIX-specific nanobody conjugated to IRDye800CW for molecular imaging of pre-invasive breast cancer. PROCEDURES: CAIX-specific nanobodies were selected using a modified phage display technology, conjugated site-specifically to IRDye800CW and evaluated

  7. Hypoxia-Targeting Fluorescent Nanobodies for Optical Molecular Imaging of Pre-Invasive Breast Cancer

    NARCIS (Netherlands)

    van Brussel, Aram S A; Adams, Arthur; Oliveira, Sabrina; Dorresteijn, Bram; El Khattabi, Mohamed; Vermeulen, Jeroen F.; van der Wall, Elsken; Mali, W.P.T.M.; Derksen, Patrick W B; van Diest, Paul J.; van Bergen En Henegouwen, Paul M P

    Purpose: The aim of this work was to develop a CAIX-specific nanobody conjugated to IRDye800CW for molecular imaging of pre-invasive breast cancer. Procedures: CAIX-specific nanobodies were selected using a modified phage display technology, conjugated site-specifically to IRDye800CW and evaluated

  8. Determination of low molecular weight thiols using monobromobimane fluorescent labeling and high-performance liquid chromatography

    Science.gov (United States)

    Fahey, Robert C.; Newton, Gerald L.

    1988-01-01

    Methods are described for the preparation and high-performance liquid chromatography (HPLC) analysis of monobromobimane derivatives of low molecular weight thiols in extracts of biological samples. Typical problems encountered in the development and application of these methods are discussed. Analysis of mung bean extract is used as an example.

  9. Magnetic resonance and fluorescence studies on pyruvate dehydrogenase complexes and their small molecular weight constituents

    NARCIS (Netherlands)

    Grande, H.J.

    1976-01-01

    The articles presented in this thesis do not describe at first glance one well-defined subject. They are, however, in fact connected by one central theme: the study of large enzyme aggregates by molecular physical methods. Chosen was the pyruvate dehydrogenase complex (PDC) because of its

  10. Multicolor Fluorescence Writing Based on Host-Guest Interactions and Force-Induced Fluorescence-Color Memory.

    Science.gov (United States)

    Matsunaga, Yuki; Yang, Jye-Shane

    2015-06-26

    A new strategy is reported for multicolor fluorescence writing on thin solid films with mechanical forces. This concept is illustrated by the use of a green-fluorescent pentiptycene derivative 1, which forms variably colored fluorescent exciplexes: a change from yellow to red was observed with anilines, and fluorescence quenching (a change to black) occurred in the presence of benzoquinone. Mechanical forces, such as grinding and shearing, induced a crystalline-to-amorphous phase transition in both the pristine and guest-adsorbed solids that led to a change in the fluorescence color (mechanofluorochromism) and a memory of the resulting color. Fluorescence drawings of five or more colors were created on glass or paper and could be readily erased by exposure to air and dichloromethane fumes. The structural and mechanistic aspects of the observations are also discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Fluorescent blood glucose monitor by hemin-functionalized graphene quantum dots based sensing system

    Energy Technology Data Exchange (ETDEWEB)

    He, Yuezhen; Wang, Xiaoxun; Sun, Jian; Jiao, Shoufeng; Chen, Hongqi; Gao, Feng; Wang, Lun, E-mail: wanglun@mail.ahnu.edu.cn

    2014-01-31

    Graphical abstract: -- Highlights: •Hemin is assembled onto the surfaces of graphene quantum dots (GQDs). •With the aid of hemin, H{sub 2}O{sub 2} could quench the FL signal of GQDs obviously. •Based on this effect, a fluorescent platform is proposed for the sensing of glucose. •The proposed method provides a new pathway to explore practical application of GQDs. -- Abstract: In the present work, a highly sensitive and specific fluorescent biosensor for blood glucose monitoring is developed based on hemin-functionalized graphene quantum dots (GQDs) and glucose oxidase (GOx) system. The GQDs which are simply prepared by pyrolyzing citric acid exhibit strong fluorescence and good water-solubility. Due to the noncovalent assembly between hemin and GQDs, the addition of hemin can make hydrogen peroxide (H{sub 2}O{sub 2}) to destroy the passivated surface of GQDs, leading to significant fluorescence quenching of GQDs. Based on this effect, a novel fluorescent platform is proposed for the sensing of glucose. Under the optimized conditions, the linear range of glucose is from 9 to 300 μM, and the limit of detection is 0.1 μM. As unique properties of GQDs, the proposed biosensor is green, simple, cost-efficient, and it is successfully applied to the determination of glucose in human serum. In addition, the proposed method provides a new pathway to further design the biosensors based on the assembly of GQDs with hemin for detection of biomolecules.

  12. Using Fluorescent Viruses for Detecting Bacteria in Water

    Science.gov (United States)

    Tabacco, Mary Beth; Qian, Xiaohua; Russo, Jaimie A.

    2009-01-01

    A method of detecting water-borne pathogenic bacteria is based partly on established molecular-recognition and fluorescent-labeling concepts, according to which bacteria of a species of interest are labeled with fluorescent reporter molecules and the bacteria can then be detected by fluorescence spectroscopy. The novelty of the present method lies in the use of bacteriophages (viruses that infect bacteria) to deliver the fluorescent reporter molecules to the bacteria of the species of interest.

  13. Modulation of a fluorescence switch based on photochromic spirooxazine in composite organic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Xiaohai [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Peng Aidong [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Fu Hongbing [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Liu Yuanyuan [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Zhao Yongsheng [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Ma Ying [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Yao Jiannian [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-04-11

    We describe a versatile and convenient approach to achieve fluorescence modulation by the preparation of composite nanoparticles (CNPs), based on photochromic 5-methoxy-1,3,3-trimethyl-9'-hydroxyspiroindolinenaphthoxazine (SO), fluorescent 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), and emissive-assistant 1,3-bis(pyrene) propane (BPP) molecules, employing doping techniques. The mechanism of the fluorescence switch is the intermolecular energy transfer as supported by both steady-state and time-resolved spectroscopy results. The addition of BPP not only enhances the contrast of the fluorescence signal between the 'ON' and 'OFF' state, but also provides a convenient way to tune the excitation wavelength for reading the fluorescence. High-contrast ON/OFF (20:1) fluorescence switching is successfully implemented in the CNPs and also in a more practical PVA film loaded with the CNPs. This system may represent an alternative to the covalent system in potentially rewritable high-density optical data or image storage utilizing luminescence intensity readout schemes.

  14. Highly sensitive and selective fluorescent assay for guanine based on the Cu(2+)/eosin Y system.

    Science.gov (United States)

    Shi, Huimin; Cui, Yi; Gong, Yijun; Feng, Suling

    2016-05-15

    A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu(2+)/eosin Y. Cu(2+) interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu(2+)/eosin Y system, guanine reacted with Cu(2+) to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5 nmol L(-1) and a linear range of 3.3-116 nmol L(-1). The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Highly sensitive and selective fluorescent assay for guanine based on the Cu2 +/eosin Y system

    Science.gov (United States)

    Shi, Huimin; Cui, Yi; Gong, Yijun; Feng, Suling

    2016-05-01

    A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu2 +/eosin Y. Cu2 + interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu2 +/eosin Y system, guanine reacted with Cu2 + to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5 nmol L- 1 and a linear range of 3.3-116 nmol L- 1. The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe.

  16. Modulation of a fluorescence switch based on photochromic spirooxazine in composite organic nanoparticles

    International Nuclear Information System (INIS)

    Sheng Xiaohai; Peng Aidong; Fu Hongbing; Liu Yuanyuan; Zhao Yongsheng; Ma Ying; Yao Jiannian

    2007-01-01

    We describe a versatile and convenient approach to achieve fluorescence modulation by the preparation of composite nanoparticles (CNPs), based on photochromic 5-methoxy-1,3,3-trimethyl-9'-hydroxyspiroindolinenaphthoxazine (SO), fluorescent 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), and emissive-assistant 1,3-bis(pyrene) propane (BPP) molecules, employing doping techniques. The mechanism of the fluorescence switch is the intermolecular energy transfer as supported by both steady-state and time-resolved spectroscopy results. The addition of BPP not only enhances the contrast of the fluorescence signal between the 'ON' and 'OFF' state, but also provides a convenient way to tune the excitation wavelength for reading the fluorescence. High-contrast ON/OFF (20:1) fluorescence switching is successfully implemented in the CNPs and also in a more practical PVA film loaded with the CNPs. This system may represent an alternative to the covalent system in potentially rewritable high-density optical data or image storage utilizing luminescence intensity readout schemes

  17. A PDMS-based cylindrical hybrid lens for enhanced fluorescence detection in microfluidic systems.

    Science.gov (United States)

    Lin, Bor-Shyh; Yang, Yu-Ching; Ho, Chong-Yi; Yang, Han-Yu; Wang, Hsiang-Yu

    2014-02-13

    Microfluidic systems based on fluorescence detection have been developed and applied for many biological and chemical applications. Because of the tiny amount of sample in the system; the induced fluorescence can be weak. Therefore, most microfluidic systems deploy multiple optical components or sophisticated equipment to enhance the efficiency of fluorescence detection. However, these strategies encounter common issues of complex manufacturing processes and high costs. In this study; a miniature, cylindrical and hybrid lens made of polydimethylsiloxane (PDMS) to improve the fluorescence detection in microfluidic systems is proposed. The hybrid lens integrates a laser focusing lens and a fluorescence collecting lens to achieve dual functions and simplify optical setup. Moreover, PDMS has advantages of low-cost and straightforward fabrication compared with conventional optical components. The performance of the proposed lens is first examined with two fluorescent dyes and the results show that the lens provides satisfactory enhancement for fluorescence detection of Rhodamine 6G and Nile Red. The overall increments in collected fluorescence signal and detection sensitivity are more than 220% of those without lens, and the detection limits of Rhodamine 6G and Nile red are lowered to 0.01 μg/mL and 0.05 μg/mL, respectively. The hybrid lens is further applied to the detection of Nile red-labeled Chlorella vulgaris cells and it increases both signal intensity and detection sensitivity by more than 520%. The proposed hybrid lens also dramatically reduces the variation in detected signal caused by the deviation in incident angle of excitation light.

  18. Controllable molecular aggregation and fluorescence properties of 1,3,4-oxadiazole derivative

    KAUST Repository

    Li, Min

    2015-10-14

    The molecular self-assembly behaviour of 2,2’-Bis-(4-hexyloxyphenyl)-bi-1,3,4-oxadiazole (BOXD-6) in solution, on surfaces and in bulk crystals, and its photo-physical properties were studied via a combination of experimental techniques and theoretical calculations. It is found that BOXD-6 molecules self-assemble into both H- and J-aggregates at moderate concentration (~10-4 M) and then transit to exclusive J-aggregates at higher concentration (~10-3 M) in tetrahydrofuran. In H-aggregation (α polymorph), BOXD-6 adopts a linear conformation and forms a one- dimensional layered structure; in J-aggregation (β polymorph), it adopts a Z-shaped conformation and form a more ordered two-dimensional layered structure. A π-stacking structure is observed in both cases, and adjacent molecules in the J-aggregation show larger displacement along the molecular long axis direction than that in H-aggregation. Although J-aggregates are almost the only component in concentrated solutions (10-3 M), both H- and J-aggregates can be obtained if concentrated solution is transformed onto substrates through a simple drop-casting method. Such a phase transition during film formation can be easily avoided by adding water as precipitator; a film with pure J-aggregates is then obtained. In order to get more information on molecular self-assembly, intermolecular interaction potential energy surfaces (PES) were evaluated via theoretical calculations at the DFT level (M062x/6-31G**). The PES not only confirm the molecular stacking structures found in crystals but also predict some other likely structures, which will be the target of future experiments.

  19. Observation of divergent La{sup 3+} ion dilute effect in two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RE{sub x}La{sub 1−x}–EBTC (RE{sup 3+}=Eu{sup 3+} or Tb{sup 3+}; EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-etracarboxylate)

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Lu [State Key Laboratory of Materials-Oriented Chemical Engineering and College of Science, Nanjing Tech University, Nanjing 210009 (China); State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Wen-Wei, E-mail: wwzhang@nju.edu.cn [State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Ren, Xiao-Ming, E-mail: xmren@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering and College of Science, Nanjing Tech University, Nanjing 210009 (China); Zuo, Jing-Lin [State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2015-10-15

    The lanthanide metal-organic frameworks (MOFs) [Ln{sub 2}(EBTC){sub 1.5}(CH{sub 3}OH){sub 4}]·6H{sub 2}O are isostructural to each other, where EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; Ln{sup 3+}=La{sup 3+}, Eu{sup 3+} and Tb{sup 3+}; and the corresponding MOF is abbreviated as Ln–EBTC. MOFs Eu–EBTC and Tb–EBTC emit intense red and green luminescence (visible by bare eyes), respectively. The molecular alloys of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC have been successfully prepared by mixing Eu{sup 3+}/Tb{sup 3+} and La{sup 3+} salts with the desired molar ratio in the starting material. Two series of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC molecular alloys are isomorphic to the parent Ln–EBTC MOFs, while exhibit divergent La{sup 3+} ion diluting effect, namely, with increasing the relative amount of La{sup 3+}, the intensity of characteristic emission arising from Tb{sup 3+} ion monotonely increases in Tb{sub x}La{sub 1−x}–EBTC molecular alloys, whereas that of Eu{sup 3+} ion shows non-monotone decrease in Eu{sub x}La{sub 1−x}–EBTC molecular alloys. The possible origin is discussed for such a divergent behavior between Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC molecular alloys. - Graphical abstract: Two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RE{sub x}La{sub 1−x}–EBTC (RE{sup 3+}=Eu{sup 3+} or Tb{sup 3+}; EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate) have been successfully prepared by mixing Eu{sup 3+}/Tb{sup 3+} and La{sup 3+} salts with the desired molar ratio in the starting material and showed photoluminescence property with divergent La{sup 3+} ion dilute effect. - Highlights: • 3-D molecular alloys of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC were prepared. • They are isomorphic to the parent Ln–EBTC MOFs. • They show photoluminescence property with divergent La

  20. A novel water-soluble 1,8-naphthalimide as a fluorescent pH-probe and a molecular logic circuit

    International Nuclear Information System (INIS)

    Georgiev, Nikolai I.; Dimitrova, Margarita D.; Krasteva, Paoleta V.; Bojinov, Vladimir B.

    2017-01-01

    A novel highly water-soluble fluorescence sensing 1,8-naphthalimide is synthesized and investigated. The novel compound is designed on the “fluorophore-receptor 1 -spacer-receptor 2 ” model as a molecular fluorescence probe for determination of ions in 100% aqueous media. The novel probe comprising hydrazide and N-methylpiperazine substituents is capable of operating simultaneously via ICT and PET signaling mechanism and of recognizing selectively protons and hydroxyl anions over the representative metal ions and anions. Due to the remarkable fluorescence changes as a function of pH the system is able to act as a three output combinatorial logic circuit with two chemical inputs. Two INHIBIT gates in fluorescence and absorption mode as well as an IMPLICATION logic gate are obtained. Because of the parallel action of both INHIBIT gates a magnitude digital comparator is achieved for the first time in this way.

  1. Catheter-based time-gated near-infrared fluorescence/OCT imaging system

    Science.gov (United States)

    Lu, Yuankang; Abran, Maxime; Cloutier, Guy; Lesage, Frédéric

    2018-02-01

    We developed a new dual-modality intravascular imaging system based on fast time-gated fluorescence intensity imaging and spectral domain optical coherence tomography (SD-OCT) for the purpose of interventional detection of atherosclerosis. A pulsed supercontinuum laser was used for fluorescence and OCT imaging. A double-clad fiber (DCF)- based side-firing catheter was designed and fabricated to have a 23 μm spot size at a 2.2 mm working distance for OCT imaging. Its single-mode core is used for OCT, while its inner cladding transports fluorescence excitation light and collects fluorescent photons. The combination of OCT and fluorescence imaging was achieved by using a DCF coupler. For fluorescence detection, we used a time-gated technique with a novel single-photon avalanche diode (SPAD) working in an ultra-fast gating mode. A custom-made delay chip was integrated in the system to adjust the delay between the excitation laser pulse and the SPAD gate-ON window. This technique allowed to detect fluorescent photons of interest while rejecting most of the background photons, thus leading to a significantly improved signal to noise ratio (SNR). Experiments were carried out in turbid media mimicking tissue with an indocyanine green (ICG) inclusion (1 mM and 100 μM) to compare the time-gated technique and the conventional continuous detection technique. The gating technique increased twofold depth sensitivity, and tenfold SNR at large distances. The dual-modality imaging capacity of our system was also validated with a silicone-based tissue-mimicking phantom.

  2. A fluorescent probe based on nitrogen doped graphene quantum dots for turn off sensing of explosive and detrimental water pollutant, TNP in aqueous medium

    Science.gov (United States)

    Kaur, Manjot; Mehta, Surinder K.; Kansal, Sushil Kumar

    2017-06-01

    This paper reports the carbonization assisted green approach for the fabrication of nitrogen doped graphene quantum dots (N-GQDs). The obtained N-GQDs displayed good water dispersibility and stability in the wide pH range. The as synthesized N-GQDs were used as a fluorescent probe for the sensing of explosive 2,4,6-trinitrophenol (TNP) in aqueous medium based on fluorescence resonance energy transfer (FRET), molecular interactions and charge transfer mechanism. The quenching efficiency was found to be linear in proportion to the TNP concentration within the range of 0-16 μM with detection limit (LOD) of 0.92 μM. The presented method was successfully applied to the sensing of TNP in tap and lake water samples with satisfactory results. Thus, N-GQDs were used as a selective, sensitive and turn off fluorescent sensor for the detection of perilous water contaminant i.e. TNP.

  3. Comparing the Spectroscopic and Molecular Characteristics of Different Dissolved Organic Matter Fractions Isolated by Hydrophobic and Anionic Exchange Resins Using Fluorescence Spectroscopy and FT-ICR-MS

    Directory of Open Access Journals (Sweden)

    Morgane Derrien

    2017-07-01

    Full Text Available Despite the environmental significance of dissolved organic matter (DOM, characterizing DOM is still challenging due to its structural complexity and heterogeneity. In this study, three different chemical fractions, including hydrophobic acid (HPOA, transphilic acid (TPIA, and hydrophilic neutral and base (HPIN/B fractions, were separated from bulk aquatic DOM samples, and their spectral features and the chemical composition at the molecular level were compared using both fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS. The HPIN/B fraction was distinguished from the two acidic fractions (i.e., HPOA and TPIA by the EEM-PARAFAC, while the TPIA fraction was discriminated by using the molecular parameters derived from the FT-ICR MS analyses. Statistical comparison suggests that the spectral dissimilarity among the three chemical fractions might result from the acido-basic properties of DOM samples, while the differences in molecular composition were more likely to be affected by the hydrophobicity of the DOM fractions. The non-metric multidimensional scaling map further revealed that the HPOA was the most heterogeneous among the three fractions. The number of overlapping formulas among the three chemical fractions constituted only <5% of all identified formulas, and those between two different fractions ranged from 2.0% to 24.1%, implying relatively homogeneous properties of the individual chemical fractions with respect to molecular composition. Although employing chemical fractionation achieved a lowering of the DOM heterogeneity, prevalent signatures of either acido-basic property or the hydrophobic nature of DOM on the characteristics of three chemical isolated fractions were not found for this study.

  4. Light extraction efficiency enhancement for fluorescent SiC based white light-emitting diodes

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

    Fluorescent SiC based white light-emitting diodes(LEDs) light source, as an innovative energy-efficient light source, would even have longer lifetime, better light quality and eliminated blue-tone effect, compared to the current phosphor based white LED light source. In this paper, the yellow...

  5. Micromotor-based on-off fluorescence detection of sarin and soman simulants.

    Science.gov (United States)

    Singh, Virendra V; Kaufmann, Kevin; Orozco, Jahir; Li, Jinxing; Galarnyk, Michael; Arya, Gaurav; Wang, Joseph

    2015-06-30

    Self-propelled micromotor-based fluorescent "On-Off" detection of nerve agents is described. The motion-based assay utilizes Si/Pt Janus micromotors coated with fluoresceinamine toward real-time "on-the-fly" field detection of sarin and soman simulants.

  6. Selective fluorescence sensors for detection of nitroaniline and metal Ions based on ligand-based luminescent metal-organic frameworks

    International Nuclear Information System (INIS)

    Yu, Zongchao; Wang, Fengqin; Lin, Xiangyi; Wang, Chengmiao; Fu, Yiyuan; Wang, Xiaojun; Zhao, Yongnan; Li, Guodong

    2015-01-01

    Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn_3L_3(DMF)_2 (1) and Zn_3L_3(DMA)_2(H_2O)_3 (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe"3"+ and Al"3"+ by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significant fluorescence quenching effect for Fe"3"+. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe"3"+ or Al"3"+.

  7. NIR-Cyanine Dye Linker: a Promising Candidate for Isochronic Fluorescence Imaging in Molecular Cancer Diagnostics and Therapy Monitoring.

    Science.gov (United States)

    Komljenovic, Dorde; Wiessler, Manfred; Waldeck, Waldemar; Ehemann, Volker; Pipkorn, Ruediger; Schrenk, Hans-Hermann; Debus, Jürgen; Braun, Klaus

    2016-01-01

    Personalized anti-cancer medicine is boosted by the recent development of molecular diagnostics and molecularly targeted drugs requiring rapid and efficient ligation routes. Here, we present a novel approach to synthetize a conjugate able to act simultaneously as an imaging and as a chemotherapeutic agent by coupling functional peptides employing solid phase peptide synthesis technologies. Development and the first synthesis of a fluorescent dye with similarity in the polymethine part of the Cy7 molecule whose indolenine-N residues were substituted with a propylene linker are described. Methylating agent temozolomide is functionalized with a tetrazine as a diene component whereas Cy7-cell penetrating peptide conjugate acts as a dienophilic reaction partner for the inverse Diels-Alder click chemistry-mediated ligation route yielding a theranostic conjugate, 3-mercapto-propionic-cyclohexenyl-Cy7-bis-temozolomide-bromide-cell penetrating peptide. Synthesis route described here may facilitate targeted delivery of the therapeutic compound to achieve sufficient local concentrations at the target site or tissue. Its versatility allows a choice of adequate imaging tags applicable in e.g. PET, SPECT, CT, near-infrared imaging, and therapeutic substances including cytotoxic agents. Imaging tags and therapeutics may be simultaneously bound to the conjugate applying click chemistry. Theranostic compound presented here offers a solid basis for a further improvement of cancer management in a precise, patient-specific manner.

  8. Fluorescence turn-on detection of target sequence DNA based on silicon nanodot-mediated quenching.

    Science.gov (United States)

    Zhang, Yanan; Ning, Xinping; Mao, Guobin; Ji, Xinghu; He, Zhike

    2018-05-01

    We have developed a new enzyme-free method for target sequence DNA detection based on the dynamic quenching of fluorescent silicon nanodots (SiNDs) toward Cy5-tagged DNA probe. Fascinatingly, the water-soluble SiNDs can quench the fluorescence of cyanine (Cy5) in Cy5-tagged DNA probe in homogeneous solution, and the fluorescence of Cy5-tagged DNA probe can be restored in the presence of target sequence DNA (the synthetic target miRNA-27a). Based on this phenomenon, a SiND-featured fluorescent sensor has been constructed for "turn-on" detection of the synthetic target miRNA-27a for the first time. This newly developed approach possesses the merits of low cost, simple design, and convenient operation since no enzymatic reaction, toxic reagents, or separation procedures are involved. The established method achieves a detection limit of 0.16 nM, and the relative standard deviation of this method is 9% (1 nM, n = 5). The linear range is 0.5-20 nM, and the recoveries in spiked human fluids are in the range of 90-122%. This protocol provides a new tactic in the development of the nonenzymic miRNA biosensors and opens a promising avenue for early diagnosis of miRNA-associated disease. Graphical abstract The SiND-based fluorescent sensor for detection of S-miR-27a.

  9. A coumarin based Schiff base probe for selective fluorescence detection of Al3 + and its application in live cell imaging

    Science.gov (United States)

    Sen, Bhaskar; Sheet, Sanjoy Kumar; Thounaojam, Romita; Jamatia, Ramen; Pal, Amarta Kumar; Aguan, Kripamoy; Khatua, Snehadrinarayan

    2017-02-01

    A new coumarin based Schiff base compound, CSB-1 has been synthesized to detect metal ion based on the chelation enhanced fluorescence (CHEF). The cation binding properties of CSB-1 was thoroughly examined in UV-vis and fluorescence spectroscopy. In fluorescence spectroscopy the compound showed high selectivity toward Al3 + ion and the Al3 + can be quantified in mixed aqueous buffer solution (MeOH: 0.01 M HEPES Buffer; 9:1; v/v) at pH 7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by 24 fold after addition of only five equivalents of Al3 +. The fluorescence titration of CSB-1 with Al3 + in mixed aqueous buffer afforded a binding constant, Ka = (1.06 ± 0.2) × 104 M- 1. The colour change from light yellow to colourless and the appearance of blue fluorescence, which can be observed by the naked eye, provides a real-time method for Al3 + sensing. Further the live cell imaging study indicated that the detection of intracellular Al3 + ions are also readily possible in living cell.

  10. Illuminating the origins of spectral properties of green fluorescent proteins via proteochemometric and molecular modeling.

    Science.gov (United States)

    Nantasenamat, Chanin; Simeon, Saw; Owasirikul, Wiwat; Songtawee, Napat; Lapins, Maris; Prachayasittikul, Virapong; Wikberg, Jarl E S

    2014-10-15

    Green fluorescent protein (GFP) has immense utility in biomedical imaging owing to its autofluorescent nature. In efforts to broaden the spectral diversity of GFP, there have been several reports of engineered mutants via rational design and random mutagenesis. Understanding the origins of spectral properties of GFP could be achieved by means of investigating its structure-activity relationship. The first quantitative structure-property relationship study for modeling the spectral properties, particularly the excitation and emission maximas, of GFP was previously proposed by us some years ago in which quantum chemical descriptors were used for model development. However, such simplified model does not consider possible effects that neighboring amino acids have on the conjugated π-system of GFP chromophore. This study describes the development of a unified proteochemometric model in which the GFP chromophore and amino acids in its vicinity are both considered in the same model. The predictive performance of the model was verified by internal and external validation as well as Y-scrambling. Our strategy provides a general solution for elucidating the contribution that specific ligand and protein descriptors have on the investigated spectral property, which may be useful in engineering novel GFP variants with desired characteristics. Copyright © 2014 Wiley Periodicals, Inc.

  11. Fluorescence-based bioassays for the detection and evaluation of food materials.

    Science.gov (United States)

    Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

    2015-10-13

    We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

  12. Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

    Directory of Open Access Journals (Sweden)

    Kentaro Nishi

    2015-10-01

    Full Text Available We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

  13. Non-destructive monitoring of agricultural product (lettuce [Lactuca sativa]) based on laser-induced fluorescence

    International Nuclear Information System (INIS)

    Ishizawa, H.; Saito, Y.; Amemiya, T.; Komatu, K.

    2002-01-01

    Quality control of agricultural products in process of cultivation and distribution has become an important problem. This paper describes a field measuring method of lettuce based on laser induced fluorescence (LIF) spectroscopy for growth monitoring. Intensity at 460nm of LIF spectra showed characteristic variations of near harvest time. The results of chemical analysis confirmed that sucrose and chlorogenic acid are origins of the 460nm fluorescence. The prediction of harvest time and the possibility of quality monitoring are discussed based on the experimental data

  14. A communication theoretical analysis of FRET-based mobile ad hoc molecular nanonetworks.

    Science.gov (United States)

    Kuscu, Murat; Akan, Ozgur B

    2014-09-01

    Nanonetworks refer to a group of nanosized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Förster Resonance Energy Transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, for the first time in the literature, we investigate the network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation based on birth-death processes with continuous time Markov chains. We evaluate the performance of FRET-MSAN and FRET-MAMNET in terms of successful transmission probability and mean extinction time of the messages, system throughput, channel capacity and achievable communication rates.

  15. Evaluation of a fluorescence-based method for antibabesial drug screening.

    Science.gov (United States)

    Guswanto, Azirwan; Sivakumar, Thillaiampalam; Rizk, Mohamed Abdo; Elsayed, Shimaa Abd Elsalam; Youssef, Mohamed Ahmed; ElSaid, ElSaid El Shirbini; Yokoyama, Naoaki; Igarashi, Ikuo

    2014-08-01

    In vitro evaluation of chemotherapeutic agents against Babesia and Theileria parasites has become routine, and the effectiveness of these chemicals is usually determined by comparing the parasitemia dynamics of untreated and treated parasites. Although microscopy is widely used to calculate parasitemia, several disadvantages are associated with this technique. The present study evaluated a fluorescence-based method using SYBR green I stain (SG I) to screen antibabesial agents in in vitro cultures of Babesia bovis. The linearity between relative fluorescence units (RFU) and parasitemia was found to be well correlated with a 0.9944 goodness-of-fit (r(2)) value. Subsequently, 50% inhibitory concentration (IC50) values were calculated for 3 antiprotozoan agents, diminazene aceturate, nimbolide, and gedunin, by this method. For diminazene aceturate and nimbolide, the IC(50)s determined by the fluorescence-based method (408 nM and 8.13 μM, respectively) and microscopy (400.3 nM and 9.4 μM, respectively) were in agreement. Furthermore, the IC50 of gedunin determined by the fluorescence-based method (19 μM) was similar to the recently described microscopy-based value (21.7 μM) for B. bovis. Additionally, the Z' factor (0.80 to 0.90), signal-to-noise (S/N) ratio (44.15 to 87.64), coefficient of variation at the maximum signal (%CVmax) (0.50 to 2.85), and coefficient of variation at the minimum signal (%CVmin) (1.23 to 2.21) calculated for the fluorescence method using diminazene aceturate were comparable to those previously determined in malaria research for this assay. These findings suggest that the fluorescence-based method might be useful for antibabesial drug screening and may have potential to be developed into a high-throughput screening (HTS) assay. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  16. Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding

    International Nuclear Information System (INIS)

    Yan, Xiu-Fang; Chen, Zeng-Ping; Cui, Yin-Yin; Hu, Yuan-Liang; Yu, Ru-Qin

    2016-01-01

    PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFM GRP ) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFM GRP has been tested on the quantitative determination of free Ca 2+ in both simulated and real turbid media using a Ca 2+ sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFM GRP could realize precise and accurate quantification of free Ca 2+ in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca 2+ bound Rhod-2. The average relative predictive error value of QFM GRP for the test simulated turbid samples was 5.9%, about 2–4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca 2+ bound Rhod-2 and eosin B. The recovery rates of QFM GRP for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry. - Highlights: • An advanced model was derived for generalized wavelength-ratiometric PEBBLEs. • The model can simplify the design of generalized wavelength-ratiometric PEBBLEs. • The model realized accurate

  17. The impact of fluorescent dyes on the performances of polystyrene-based plastic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jun [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Engineering Research Center of High Performance Polymer and Molding Technology, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621010 (China); Deng, Cheng; Jiang, Huimin [Engineering Research Center of High Performance Polymer and Molding Technology, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042 (China); Zheng, Zhanlong; Gong, Rui [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621010 (China); Bi, Yutie [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621010 (China); Zhang, Lin, E-mail: zhlmy@sina.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Lin, Runxiong, E-mail: qdlrx@qust.edu.cn [Engineering Research Center of High Performance Polymer and Molding Technology, Ministry of Education, Qingdao University of Science and Technology, Qingdao 266042 (China)

    2016-11-01

    To investigate the influence of both the first luminescent additive and the wavelength-shifter on the performance of plastic scintillator, a series of polystyrene-based scintillator had been prepared by thermal polymerization. Three first luminescent additives (PPO, p-TP and b-PBD) and four wavelength-shifters (POPOP, Bis-MSB, Me-MSB and DPA) were added to the scintillators respectively. The comparison results showed that PPO and POPOP were the most adequate fluorescent dyes for the polystyrene-based plastic scintillator. Moreover, with the increase of the concentration of PPO and POPOP, the fluorescence intensity and light yield were increased firstly and then decreased. The plastic scintillator containing 2% PPO and 0.02% POPOP had the highest fluorescence intensity and light yield.

  18. The impact of fluorescent dyes on the performances of polystyrene-based plastic scintillators

    International Nuclear Information System (INIS)

    Zhu, Jun; Deng, Cheng; Jiang, Huimin; Zheng, Zhanlong; Gong, Rui; Bi, Yutie; Zhang, Lin; Lin, Runxiong

    2016-01-01

    To investigate the influence of both the first luminescent additive and the wavelength-shifter on the performance of plastic scintillator, a series of polystyrene-based scintillator had been prepared by thermal polymerization. Three first luminescent additives (PPO, p-TP and b-PBD) and four wavelength-shifters (POPOP, Bis-MSB, Me-MSB and DPA) were added to the scintillators respectively. The comparison results showed that PPO and POPOP were the most adequate fluorescent dyes for the polystyrene-based plastic scintillator. Moreover, with the increase of the concentration of PPO and POPOP, the fluorescence intensity and light yield were increased firstly and then decreased. The plastic scintillator containing 2% PPO and 0.02% POPOP had the highest fluorescence intensity and light yield.

  19. Salicylimine-Based Colorimetric and Fluorescent Chemosensor for Selective Detection of Cyanide in Aqueous Buffer

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Jin Young; Hwang, In Hong; Kim, Hyun; Song, Eun Joo; Kim, Kyung Beom; Kim, Cheal [Seoul National Univ., Seoul (Korea, Republic of)

    2013-07-15

    A simple colorimetric and fluorescent anion sensor 1 based on salicylimine showed a high selectivity and sensitivity for detection of cyanide in aqueous solution. The receptor 1 showed high selectivity toward CN{sup -} ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to orange and a dramatic enhancement in fluorescence intensity selectively for cyanide anions over other anions. Such selectivity resulted from the nucleophilic addition of CN{sup -} to the carbon atom of an electron-deficient imine group. The sensitivity of the fluorescence-based assay (0.06 μM) is below the 1.9 μM suggested by the World Health Organization (WHO) as the maximum allowable cyanide concentration in drinking water, capable of being a practical system for the monitoring of CN. concentrations in aqueous samples.

  20. A rhodol-based fluorescent chemosensor for hydrazine and its application in live cell bioimaging

    Science.gov (United States)

    Tiensomjitr, Khomsan; Noorat, Rattha; Wechakorn, Kanokorn; Prabpai, Samran; Suksen, Kanoknetr; Kanjanasirirat, Phongthon; Pewkliang, Yongyut; Borwornpinyo, Suparerk; Kongsaeree, Palangpon

    2017-10-01

    A rhodol cinnamate fluorescent chemosensor (RC) has been developed for selective detection of hydrazine (N2H4). In aqueous medium, the rhodol-based probe exhibited high selectivity for hydrazine among other molecules. The addition of hydrazine triggered a fluorescence emission with 48-fold enhancement based on hydrazinolysis and a subsequent ring-opening process. The chemical probe also displayed a selective colorimetric response toward N2H4 from colorless solution to pink, readily observed by the naked eye. The detection limit of RC for hydrazine was calculated to be 300 nM (9.6 ppb). RC is membrane permeable and was successfully demonstrated to detect hydrazine in live HepG2 cells by confocal fluorescence microscopy.

  1. Gas Sensors Based on Molecular Imprinting Technology

    OpenAIRE

    Zhang, Yumin; Zhang, Jin; Liu, Qingju

    2017-01-01

    Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size and functional groups. MIT has been successfully applied to analyze; separate and detect macromolecular organic compounds. Furthermore; it has been increasingly applied in assays of biological mac...

  2. Synthesis and application of a highly selective copper ions fluorescent probe based on the coumarin group

    Science.gov (United States)

    He, Guangjie; Liu, Xiangli; Xu, Jinhe; Ji, Liguo; Yang, Linlin; Fan, Aiying; Wang, Songjun; Wang, Qingzhi

    2018-02-01

    A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV-vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH3CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu2 + ions within living cells.

  3. Computer-assisted sperm morphometry fluorescence-based analysis has potential to determine progeny sex

    Directory of Open Access Journals (Sweden)

    Pilar Santolaria

    2016-01-01

    Full Text Available This study was designed to determine the ability of computer-assisted sperm morphometry analysis (CASA-Morph with fluorescence to discriminate between spermatozoa carrying different sex chromosomes from the nuclear morphometrics generated and different statistical procedures in the bovine species. The study was divided into two experiments. The first was to study the morphometric differences between X- and Y-chromosome-bearing spermatozoa (SX and SY, respectively. Spermatozoa from eight bulls were processed to assess simultaneously the sex chromosome by FISH and sperm morphometry by fluorescence-based CASA-Morph. SX cells were larger than SY cells on average (P < 0.001 although with important differences between bulls. A simultaneous evaluation of all the measured features by discriminant analysis revealed that nuclear area and average fluorescence intensity were the variables selected by stepwise discriminant function analysis as the best discriminators between SX and SY. In the second experiment, the sperm nuclear morphometric results from CASA-Morph in nonsexed (mixed SX and SY and sexed (SX semen samples from four bulls were compared. FISH allowed a successful classification of spermatozoa according to their sex chromosome content. X-sexed spermatozoa displayed a larger size and fluorescence intensity than nonsexed spermatozoa (P < 0.05. We conclude that the CASA-Morph fluorescence-based method has the potential to find differences between X- and Y-chromosome-bearing spermatozoa in bovine species although more studies are needed to increase the precision of sex determination by this technique.

  4. Intrinsic fluorescence for cervical precancer detection using polarized light based in-house fabricated portable device

    Science.gov (United States)

    Meena, Bharat Lal; Singh, Pankaj; Sah, Amar Nath; Pandey, Kiran; Agarwal, Asha; Pantola, Chayanika; Pradhan, Asima

    2018-01-01

    An in-house fabricated portable device has been tested to detect cervical precancer through the intrinsic fluorescence from human cervix of the whole uterus in a clinical setting. A previously validated technique based on simultaneously acquired polarized fluorescence and polarized elastic scattering spectra from a turbid medium is used to extract the intrinsic fluorescence. Using a diode laser at 405 nm, intrinsic fluorescence of flavin adenine dinucleotide, which is the dominant fluorophore and other contributing fluorophores in the epithelium of cervical tissue, has been extracted. Different grades of cervical precancer (cervical intraepithelial neoplasia; CIN) have been discriminated using principal component analysis-based Mahalanobis distance and linear discriminant analysis. Normal, CIN I and CIN II samples have been discriminated from one another with high sensitivity and specificity at 95% confidence level. This ex vivo study with cervix of whole uterus samples immediately after hysterectomy in a clinical environment indicates that the in-house fabricated portable device has the potential to be used as a screening tool for in vivo precancer detection using intrinsic fluorescence.

  5. A sol-gel based molecular imprint incorporating carbon dots for fluorometric determination of nicotinic acid

    International Nuclear Information System (INIS)

    Zuo, Pengli; Gao, Junfa; Liu, Jianha; Zhao, Mingming; Zhao, Jiahong; Peng, Jun; Zuo, Pengjian; He, Hua

    2016-01-01

    We are introducing functionalized carbon dots (C-dots) coated with a shell of molecularly imprinted sol-gel as a new tool in molecular imprint-based detection. Specifically, an imprint recognizing nicotinic acid (NA) was prepared in two steps. The first involves pyrolytic decomposition of citric acid in the presence of aminopropyltriethoxysilane to yield triethoxysilyl-modified C-dots with a typical size of 2.8 ± 1.1 nm. These are then polycondensed in the presence of tetraethoxysilane and NA at room temperature to give spherical silica nanoparticles (SiNPs) with a typical size of ∼300 nm and containing C-dots and NA in the silica matrix. NA was then removed by extraction. The resulting SiNPs are well permeable to NA, photostable, display strong blue luminescence and can bind NA fairly selectively. The fluorometric detection scheme is based on the finding that increasing concentrations of NA quench the fluorescence of the C-dots in the SiNPs. NA can be determined by this method in the 0.5 to 10.5 μM concentration range, with a 12.6 nM detection limit. The composite was successfully utilized as a fluorescent probe for the determination of NA in spiked human urine samples. The method is believed to have a wider scope in being applicable to other analytes that are capable of quenching the fluorescence of C-dots. (author)

  6. From fast fluorescence imaging to molecular diffusion law on live cell membranes in a commercial microscope.

    Science.gov (United States)

    Di Rienzo, Carmine; Gratton, Enrico; Beltram, Fabio; Cardarelli, Francesco

    2014-10-09

    It has become increasingly evident that the spatial distribution and the motion of membrane components like lipids and proteins are key factors in the regulation of many cellular functions. However, due to the fast dynamics and the tiny structures involved, a very high spatio-temporal resolution is required to catch the real behavior of molecules. Here we present the experimental protocol for studying the dynamics of fluorescently-labeled plasma-membrane proteins and lipids in live cells with high spatiotemporal resolution. Notably, this approach doesn't need to track each molecule, but it calculates population behavior using all molecules in a given region of the membrane. The starting point is a fast imaging of a given region on the membrane. Afterwards, a complete spatio-temporal autocorrelation function is calculated correlating acquired images at increasing time delays, for example each 2, 3, n repetitions. It is possible to demonstrate that the width of the peak of the spatial autocorrelation function increases at increasing time delay as a function of particle movement due to diffusion. Therefore, fitting of the series of autocorrelation functions enables to extract the actual protein mean square displacement from imaging (iMSD), here presented in the form of apparent diffusivity vs average displacement. This yields a quantitative view of the average dynamics of single molecules with nanometer accuracy. By using a GFP-tagged variant of the Transferrin Receptor (TfR) and an ATTO488 labeled 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphoethanolamine (PPE) it is possible to observe the spatiotemporal regulation of protein and lipid diffusion on µm-sized membrane regions in the micro-to-milli-second time range.

  7. Emergence of White Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence

    Directory of Open Access Journals (Sweden)

    Peng Xiao

    2018-02-01

    Full Text Available Recently, thermally activated delayed fluorescence (TADF organic light-emitting diodes (OLEDs have attracted both academic and industrial interest due to their extraordinary characteristics, such as high efficiency, low driving voltage, bright luminance, lower power consumption and potentially long lifetime. In this invited review, the fundamental concepts of TADF have been firstly introduced. Then, main approaches to realize WOLEDs based on TADF have been summarized. More specifically, the recent development of WOLEDs based on all TADF emitters, WOLEDs based on TADF and conventional fluorescence emitters, hybrid WOLEDs based on blue TADF and phosphorescence emitters and WOLEDs based on TADF exciplex host and phosphorescence dopants is highlighted. In particular, design strategies, device structures, working mechanisms and electroluminescent processes of the representative WOLEDs based on TADF are reviewed. Finally, challenges and opportunities for further enhancement of the performance of WOLEDs based on TADF are presented.

  8. A dihydrazone based fluorescent probe for selective determination of Al{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Pratap Singh, Divya; Singh, Vinod P., E-mail: singvp@yahoo.co.in

    2014-11-15

    A highly selective fluorescent sensor N,N′-bis((2-hydroxynaphthalen-1-yl)methylene) oxalohydrazide (H{sub 2}ohn) for the determination of Al{sup 3+} ions was synthesized and characterized by different physico-chemical and spectroscopic techniques. The single crystal structure of H{sub 2}ohn receptor has also been reported. The H{sub 2}ohn shows an enhanced fluorescence in the presence of Al{sup 3+} ions in ethanol–water (2:3 v/v) solution. Other cations viz. Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Mn{sup 2+}, Fe{sup 3+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, Pb{sup 2+}, Cd{sup 2+} and Hg{sup 2+} show no appreciable change in fluorescence intensity. The binding mode of H{sub 2}ohn receptor with Al{sup 3+} was studied by UV–visible, fluorescence and {sup 1}H NMR titrations. The receptor acts as a dibasic hexadentate ligand and interacts with two Al{sup 3+} ions with a high binding constant K{sub B}=2.62×10{sup 11} M{sup −2}. The lowest detection limit for Al{sup 3+} complex of H{sub 2}ohn was determined to be 8.56×10{sup −10} M. The structures of H{sub 2}ohn and its Al(III) complex were also optimized by DFT calculations. - Highlights: • A dihydrazone based fluorescent sensor is synthesized. • Characterized by IR, NMR, UV−visible and mass spectral analysis. • The receptor serves as a selective fluorescent sensor for Al{sup 3+} over other cations. • The sensing property is monitored by UV−visible, fluorescence and NMR spectroscopy. • A high binding constant of the receptor with Al{sup 3+} is reported here.

  9. PET-based molecular imaging in neuroscience

    International Nuclear Information System (INIS)

    Jacobs, A.H.; Heiss, W.D.; Li, H.; Knoess, C.; Schaller, B.; Kracht, L.; Monfared, P.; Vollmar, S.; Bauer, B.; Wagner, R.; Graf, R.; Wienhard, K.; Winkeler, A.; Rueger, A.; Klein, M.; Hilker, R.; Galldiks, N.; Herholz, K.; Sobesky, J.

    2003-01-01

    Positron emission tomography (PET) allows non-invasive assessment of physiological, metabolic and molecular processes in humans and animals in vivo. Advances in detector technology have led to a considerable improvement in the spatial resolution of PET (1-2 mm), enabling for the first time investigations in small experimental animals such as mice. With the developments in radiochemistry and tracer technology, a variety of endogenously expressed and exogenously introduced genes can be analysed by PET. This opens up the exciting and rapidly evolving field of molecular imaging, aiming at the non-invasive localisation of a biological process of interest in normal and diseased cells in animal models and humans in vivo. The main and most intriguing advantage of molecular imaging is the kinetic analysis of a given molecular event in the same experimental subject over time. This will allow non-invasive characterisation and ''phenotyping'' of animal models of human disease at various disease stages, under certain pathophysiological stimuli and after therapeutic intervention. The potential broad applications of imaging molecular events in vivo lie in the study of cell biology, biochemistry, gene/protein function and regulation, signal transduction, transcriptional regulation and characterisation of transgenic animals. Most importantly, molecular imaging will have great implications for the identification of potential molecular therapeutic targets, in the development of new treatment strategies, and in their successful implementation into clinical application. Here, the potential impact of molecular imaging by PET in applications in neuroscience research with a special focus on neurodegeneration and neuro-oncology is reviewed. (orig.)

  10. Chiral recognition of proteins having L-histidine residues on the surface with lanthanide ion complex incorporated-molecularly imprinted fluorescent nanoparticles.

    Science.gov (United States)

    Uzun, Lokman; Uzek, Recep; Senel, Serap; Say, Ridvan; Denizli, Adil

    2013-08-01

    In this study, lanthanide ion complex incorporated molecularly imprinted fluorescent nanoparticles were synthesized. A combination of three novel approaches was applied for the purpose. First, lanthanide ions [Terbium(III)] were complexed with N-methacryloyl-L-histidine (MAH), polymerizable derivative of L-histidine amino acid, in order to incorporate the complex directly into the polymeric backbone. At the second stage, L-histidine molecules imprinted nanoparticles were utilized instead of whole protein imprinting in order to avoid whole drawbacks such as fragility, complexity, denaturation tendency, and conformation dependency. At the third stage following the first two steps mentioned above, imprinted L-histidine was coordinated with cupric ions [Cu(II)] to conduct the study under mild conditions. Then, molecularly imprinted fluorescent nanoparticles synthesized were used for L-histidine adsorption from aqueous solution to optimize conditions for adsorption and fluorimetric detection. Finally, usability of nanoparticles was investigated for chiral biorecognition using stereoisomer, D-histidine, racemic mixture, D,L-histidine, proteins with surface L-histidine residue, lysozyme, cytochrome C, or without ribonuclease A. The results revealed that the proposed polymerization strategy could make significant contribution to the solution of chronic problems of fluorescent component introduction into polymers. Additionally, the fluorescent nanoparticles reported here could be used for selective separation and fluorescent monitoring purposes. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Guo

    2016-10-01

    Full Text Available The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein.

  12. Surface recognition and fluorescence sensing of histone by dansyl-appended cyclophane-based resorcinarene trimer.

    Science.gov (United States)

    Hayashida, Osamu; Ogawa, Naoyuki; Uchiyama, Masaki

    2007-11-07

    A cyclophane-based resorcinarene trimer (3) bearing a dansyl moiety as an environmentally sensitive fluorophore was prepared by stepwise condensation of a tetraaza[6.1.6.1]paracyclophane skeleton with a dansyl moiety and three resorcinarene derivatives having heptacarboxylic acid residues in this sequence. The dansyl-appended cyclophane exhibited the following fluorescence properties regarding solvent polarity dependency and histone surface recognition: With increasing dioxane contents in dioxane/water solvents, the fluorescence intensity originating from the dansyl moiety of 3 increased along with a concomitant blue shift of the fluorescence maximum (lambdaem). The microenvironmentally sensitive fluorescence properties of dansyl fluorophore were maintained, even when the dansyl moiety was covalently attached to a cyclophane. Most interestingly, the cyclophane-based resorcinarene trimer exhibited recognition and fluorescence sensing capabilities toward histone, a small basic protein of eukaryotic chromatins. The fluorescence intensity originating from 3 increased along with a concomitant blue shift of lambdaem upon the addition of histone, reflecting the formation of 3-histone complexes. A relatively large fluorescence polarization (P) value was obtained for the 3-histone complexes (0.15), reflecting highly restricted conformations of 3, and the obtained P value was much larger than that of 3 alone in aqueous medium (0.07). The binding constant (K) of 3 with histone (unit basis) was estimated to be 2.1 x 106 M-1. On the other hand, upon the addition of acetylated histone (Ac-histone) to an aqueous solution containing 3, the extent of change in fluorescence intensity originating from the dansyl group of 3 was almost negligible, indicating that the electrostatic interactions between 3 and Ac-histone were weak. In addition, the fluorescence spectral changes were also small or negligible upon the addition of other proteins such as albumin, ovalbumin, peanut agglutinin

  13. Label-free detection of kanamycin based on a G-quadruplex DNA aptamer-based fluorescent intercalator displacement assay

    Science.gov (United States)

    Xing, Yun-Peng; Liu, Chun; Zhou, Xiao-Hong; Shi, Han-Chang

    2015-01-01

    This work was the first to report that the kanamycin-binding DNA aptamer (5'-TGG GGG TTG AGG CTA AGC CGA-3') can form stable parallel G-quadruplex DNA (G4-DNA) structures by themselves and that this phenomenon can be verified by nondenaturing polyacrylamide gel electrophoresis and circular dichroism spectroscopy. Based on these findings, we developed a novel label-free strategy for kanamycin detection based on the G4-DNA aptamer-based fluorescent intercalator displacement assay with thiazole orange (TO) as the fluorescence probe. In the proposed strategy, TO became strongly fluorescent upon binding to kanamycin-binding G4-DNA. However, the addition of kanamycin caused the displacement of TO from the G4-DNA-TO conjugate, thereby resulting in decreased fluorescent signal, which was inversely related to the kanamycin concentration. The detection limit of the proposed assay decreased to 59 nM with a linear working range of 0.1 μM to 20 μM for kanamycin. The cross-reactivity against six other antibiotics was negligible compared with the response to kanamycin. A satisfactory recovery of kanamycin in milk samples ranged from 80.1% to 98.0%, confirming the potential of this bioassay in the measurement of kanamycin in various applications. Our results also served as a good reference for developing similar fluorescent G4-DNA-based bioassays in the future.

  14. Compound parabolic concentrator optical fiber tip for FRET-based fluorescent sensors

    DEFF Research Database (Denmark)

    Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren

    2015-01-01

    The Compound Parabolic Concentrator (CPC) optical fiber tip shape has been proposed for intensity based fluorescent sensors working on the principle of FRET (Förster Resonance Energy Transfer). A simple numerical Zemax model has been used to optimize the CPC tip geometry for a step-index multimode...... polymer optical fiber for an excitation and emission wavelength of 550 nm and 650nm, respectively. The model suggests an increase of a factor of 1.6 to 4 in the collected fluorescent power for an ideal CPC tip, as compared to the plane-cut fiber tip for fiber lengths between 5 and 45mm...

  15. A benzothiazole-based fluorescent probe for hypochlorous acid detection and imaging in living cells

    Science.gov (United States)

    Nguyen, Khac Hong; Hao, Yuanqiang; Zeng, Ke; Fan, Shengnan; Li, Fen; Yuan, Suke; Ding, Xuejing; Xu, Maotian; Liu, You-Nian

    2018-06-01

    A benzothiazole-based turn-on fluorescent probe with a large Stokes shift (190 nm) has been developed for hypochlorous acid detection. The probe displays prompt fluorescence response for HClO with excellent selectivity over other reactive oxygen species as well as a low detection limit of 0.08 μM. The sensing mechanism involves the HClO-induced specific oxidation of oxime moiety of the probe to nitrile oxide, which was confirmed by HPLC-MS technique. Furthermore, imaging studies demonstrated that the probe is cell permeable and can be applied to detect HClO in living cells.

  16. The detection of melamine base on a turn-on fluorescence of DNA-Ag nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Peisi [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong (China); Zhan, Yuanjin; Wu, Mei; Guo, Longhua; Lin, Zhenyu [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Qiu, Bin, E-mail: summer328cn@163.com [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Chen, Guonan [Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, Fuzhou University, Fuzhou 350002 (China); Cai, Zongwei [State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong (China)

    2017-06-15

    A label-free, ultra-sensitive and turn-on fluorescence method to detect melamine has been developed. The strategy uses the DNA-Ag nanoclusters (DNA-AgNCs) as the fluorescence probe. The fluorescence of DNA-AgNCs can be quenched in presence of Hg{sup 2+}. However, When Hg{sup 2+} and melamine were reacted for 15 min at 1000 rmp then introduced into DNA-AgNCs solution, a strong fluorescence recovery could be found. Based on this methodology, the changing fluorescent intensity has a linear relationship with melamine in the range of 0.2 μM to 4 μM (R{sup 2}=0.997). The detection limit down to 0.1 μM was obtained, which is 200 times lower than the melamine safety limit of 20 μM estimated by the US Food and Drug Administration. In addition, we had been successfully applied this method to detect melamine in milk powder and raw milk.

  17. A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH.

    Science.gov (United States)

    Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona; Eslami, Abbas; Emami, Saeed

    2015-06-05

    Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (K(a)=3582.88 M(-1)) and selectivity for fructose over glucose at pH=7.4. The sensor 1 showed a linear response toward d-fructose in the concentrations ranging from 2.5×10(-5) to 4×10(-4) mol L(-1) with the detection limit of 1.3×10(-5) mol L(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

  18. The sensitivity and selectivity properties of a fluorescence sensor based on quinoline-Bodipy

    Energy Technology Data Exchange (ETDEWEB)

    Nuri Kursunlu, Ahmed, E-mail: ankursunlu@gmail.com; Guler, Ersin

    2014-01-15

    A novel florescence sensor (Q-BODIPY) based on quinoline-Bodipy (quinoline-boradiazaindacene) was prepared by ‘click chemistry’ in several stages. The sensing actions of Q-BODIPY were confirmed by UV–vis titration, emission and excitation spectroscopic studies in presence of Mn{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, Cd{sup 2+}, Sn{sup 2+}, Hg{sup 2+}, Pb{sup 2+}, La{sup 3+}, Ga{sup 3+}, Er{sup 3+} and Yb{sup 3+} ions in methanol:H{sub 2}O (1:1) medium. Whereas some metal ions can only cause quenching effect on the fluorescence intensity of Q-BODIPY, some of them show an increase in fluorescence intensity. The stoichiometry of host–guest complexes formed was determined by Job′s plot method. The binding constants were calculated by Stern–Volmer method. As a fluorescence sensor, Q-BODIPY shows the best selectivity performance against Zn{sup 2+} ions in according to all spectroscopic data. -- Highlights: • Q-BODIPY prepared by several techniques shows a fluorescent behavior toward p, d and f block metal ions. • Q-BODIPY has both a more sensitivity and more effective ability for the detection of Zn(II) ion. • The synthesis strategies to produce Bodipy′s with metal coordinating offer a new approach for the design of novel fluorescence sensors.

  19. [1,10]Phenanthroline based cyanine dyes as fluorescent probes for ribonucleic acids in live cells

    Science.gov (United States)

    Kovalska, Vladyslava; Kuperman, Marina; Varzatskii, Oleg; Kryvorotenko, Dmytro; Kinski, Elisa; Schikora, Margot; Janko, Christina; Alexiou, Christoph; Yarmoluk, Sergiy; Mokhir, Andriy

    2017-12-01

    A series of monomethine, trimethine- and styrylcyanine dyes based on a [1,10]phenanthroline moiety was synthesized, characterized and investigated as potential fluorescent probes for nucleic acids in cell free settings and in cells. The dyes were found to be weakly fluorescent in the unbound state, whereas upon the binding to dsDNA or RNA their emission intensity raised up to 50 times (for monomethine benzothiazole derivative FT1 complexed with RNA). The strongest fluorescence intensity in assemblies with dsDNA and RNA was observed for the trimethine benzothiazole derivative FT4. The quantum yield of FT4 fluorescence in its complex with dsDNA was found to be 1.5% and the binding constant (K b) was estimated to be 7.9 × 104 M-1 that is a typical value for intercalating molecules. The FT4 dye was found to be cell membrane permeable. It stains RNA rich components—the nucleoli and most probably the cytoplasmic RNA. FT4 bound to RNAs delivers a very strong fluorescence signal, which makes this easily accessible dye a potentially useful alternative to known RNA stains, e.g. expensive SYTO® 83. The advantage of FT4 is its easy synthetic access including no chromatographic purification steps, which will be reflected in its substantially lower price.

  20. Specific detection of Vibrio parahaemolyticus by fluorescence quenching immunoassay based on quantum dots.

    Science.gov (United States)

    Wang, Ling; Zhang, Junxian; Bai, Haili; Li, Xuan; Lv, Pintian; Guo, Ailing

    2014-07-01

    In this study, anti-Vibrio parahaemolyticus polyclonal and monoclonal antibodies were prepared through intradermal injection immune and lymphocyte hybridoma technique respectively. CdTe quantum dots (QDs) were synthesized at pH 9.3, 98 °C for 1 h with stabilizer of 2.7:1. The fluorescence intensity was 586.499, and the yield was 62.43%. QD probes were successfully prepared under the optimized conditions of pH 7.4, 37 °C for 1 h, 250 μL of 50 mg/mL EDC · HCl, 150 μL of 4 mg/mL NHS, buffer system of Na2HPO4-citric acid, and 8 μL of 2.48 mg/mL polyclonal antibodies. As gold nanoparticles could quench fluorescence of quantum dots, the concentration of V. parahaemolyticus could be detected through measuring the reduction of fluorescence intensity in immune sandwich reaction composed of quantum dot probe, gold-labeled antibody, and the sample. For pure culture, fluorescence intensity of the system was proportional with logarithm concentration of antigen, and the correlation coefficient was 99.764%. The fluorescence quenching immunoassay based on quantum dots is established for the first time to detect Vibrio parahaemolyticus. This method may be used as rapid testing procedure due to its high simplicity and sensitivity.

  1. Multicolor-based discrimination of 21 short tandem repeats and amelogenin using four fluorescent universal primers.

    Science.gov (United States)

    Asari, Masaru; Okuda, Katsuhiro; Hoshina, Chisato; Omura, Tomohiro; Tasaki, Yoshikazu; Shiono, Hiroshi; Matsubara, Kazuo; Shimizu, Keiko

    2016-02-01

    The aim of this study was to develop a cost-effective genotyping method using high-quality DNA for human identification. A total of 21 short tandem repeats (STRs) and amelogenin were selected, and fluorescent fragments at 22 loci were simultaneously amplified in a single-tube reaction using locus-specific primers with 24-base universal tails and four fluorescent universal primers. Several nucleotide substitutions in universal tails and fluorescent universal primers enabled the detection of specific fluorescent fragments from the 22 loci. Multiplex polymerase chain reaction (PCR) produced intense FAM-, VIC-, NED-, and PET-labeled fragments ranging from 90 to 400 bp, and these fragments were discriminated using standard capillary electrophoretic analysis. The selected 22 loci were also analyzed using two commercial kits (the AmpFLSTR Identifiler Kit and the PowerPlex ESX 17 System), and results for two loci (D19S433 and D16S539) were discordant between these kits due to mutations at the primer binding sites. All genotypes from the 100 samples were determined using 2.5 ng of DNA by our method, and the expected alleles were completely recovered. Multiplex 22-locus genotyping using four fluorescent universal primers effectively reduces the costs to less than 20% of genotyping using commercial kits, and our method would be useful to detect silent alleles from commercial kit analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. 2D fluorescence spectroscopy for monitoring ion-exchange membrane based technologies - Reverse electrodialysis (RED).

    Science.gov (United States)

    Pawlowski, Sylwin; Galinha, Claudia F; Crespo, João G; Velizarov, Svetlozar

    2016-01-01

    Reverse electrodialysis (RED) is one of the emerging, membrane-based technologies for harvesting salinity gradient energy. In RED process, fouling is an undesirable operation constraint since it leads to a decrease of the obtainable net power density due to increasing stack electric resistance and pressure drop. Therefore, early fouling detection is one of the main challenges for successful RED technology implementation. In the present study, two-dimensional (2D) fluorescence spectroscopy was used, for the first time, as a tool for fouling monitoring in RED. Fluorescence excitation-emission matrices (EEMs) of ion-exchange membrane surfaces and of natural aqueous streams were acquired during one month of a RED stack operation. Fouling evolvement on the ion-exchange membrane surfaces was successfully followed by 2D fluorescence spectroscopy and quantified using principal components analysis (PCA). Additionally, the efficiency of cleaning strategy was assessed by measuring the membrane fluorescence emission intensity before and after cleaning. The anion-exchange membrane (AEM) surface in contact with river water showed to be significantly affected due to fouling by humic compounds, which were found to cross through the membrane from the lower salinity (river water) to higher salinity (sea water) stream. The results obtained show that the combined approach of using 2D fluorescence spectroscopy and PCA has a high potential for studying fouling development and membrane cleaning efficiency in ion exchange membrane processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Synthesis and characterization of titania-based monodisperse fluorescent europium nanoparticles for biolabeling

    International Nuclear Information System (INIS)

    Tan Mingqian; Wang Guilan; Ye Zhiqiang; Yuan Jingli

    2006-01-01

    Inorganic-organic hybrid titania-based nanoparticles covalently bound to a fluorescent Eu 3+ chelate of 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl) chlorosulfo-o-terphenyl (BHHCT-Eu 3+ ) were synthesized by a sol-gel technique. A conjugate of BHHCT with 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (APTS) was used as a precursor for the nanoparticle preparation and monodisperse nanoparticles consisting of titania network and silica sub-network covalently bound to the Eu 3+ chelate were prepared by the copolymerization of APTS-BHHCT conjugate, titanium tetraisopropoxide (TTIP) and free APTS in EuCl 3 water-alcohol solution. The effects of reaction conditions on size and fluorescence lifetime of the nanoparticles were investigated. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are near spherical and strongly fluorescent having a fluorescence quantum yield of 11.6% and a long fluorescence lifetime of ∼0.4 ms. The direct-introduced amino groups on the nanoparticle's surface by using free APTS in nanoparticle preparation facilitated the biolabeling process of the nanoparticles. The nanoparticle-labeled streptavidin (SA) was prepared and used in a sandwich-type time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid phase carrier. The method gives a detection limit of 66 pg/ml for the PSA assay

  4. Detection of DNA hybridization based on SnO2 nanomaterial enhanced fluorescence

    International Nuclear Information System (INIS)

    Gu Cuiping; Huang Jiarui; Ni Ning; Li Minqiang; Liu Jinhuai

    2008-01-01

    In this paper, enhanced fluorescence emissions were firstly investigated based on SnO 2 nanomaterial, and its application in the detection of DNA hybridization was also demonstrated. The microarray of SnO 2 nanomaterial was fabricated by the vapour phase transport method catalyzed by patterned Au nanoparticles on a silicon substrate. A probe DNA was immobilized on the substrate with patterned SnO 2 nanomaterial, respectively, by covalent and non-covalent linking schemes. When a fluorophore labelled target DNA was hybridized with a probe DNA on the substrate, fluorescence emissions were only observed on the surface of SnO 2 nanomaterial, which indicated the property of enhancing fluorescence signals from the SnO 2 nanomaterial. By comparing the different fluorescence images from covalent and non-covalent linking schemes, the covalent method was confirmed to be more effective for immobilizing a probe DNA. With the combined use of SnO 2 nanomaterial and the covalent linking scheme, the target DNA could be detected at a very low concentration of 10 fM. And the stability of SnO 2 nanomaterial under the experimental conditions was also compared with silicon nanowires. The findings strongly suggested that SnO 2 nanomaterial could be extensively applied in detections of biological samples with enhancing fluorescence property and high stability

  5. Fluorescence suppression using wavelength modulated Raman spectroscopy in fiber-probe-based tissue analysis.

    Science.gov (United States)

    Praveen, Bavishna B; Ashok, Praveen C; Mazilu, Michael; Riches, Andrew; Herrington, Simon; Dholakia, Kishan

    2012-07-01

    In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30  s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.

  6. A fluorescence resonance energy transfer-based method for histone methyltransferases

    DEFF Research Database (Denmark)

    Devkota, Kanchan; Lohse, Brian; Nyby Jakobsen, Camilla

    2015-01-01

    A simple dye–quencher fluorescence resonance energy transfer (FRET)-based assay for methyltransferases was developed and used to determine kinetic parameters and inhibitory activity at EHMT1 and EHMT2. Peptides mimicking the truncated histone H3 tail were functionalized in each end with a dye...

  7. Water soluble chromone Schiff base derivatives as fluorescence receptor for aluminium(III)

    Czech Academy of Sciences Publication Activity Database

    Jakubek, M.; Kejík, Z.; Parchaňský, Václav; Kaplánek, R.; Vasina, L.; Martásek, P.; Král, V.

    2017-01-01

    Roč. 29, č. 1 (2017), s. 1-7 ISSN 1061-0278 R&D Projects: GA TA ČR(CZ) TE01020028 Institutional support: RVO:61388963 Keywords : aluminium sensing * chelator * chromone * fluorescence * Schiff base Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.264, year: 2016

  8. Microprocessor-based system for automatic X-ray diffraction and fluorescence

    International Nuclear Information System (INIS)

    Souza, A.M. de; Carmo, L.C.S. do; Pereira, V.J.E.; Soares, E.A.

    1984-01-01

    A data acquisition and processing device appropriate for X-ray analysis and goniometer control was built. The Z-80 based system as well as the whole architeture is described. The advantages and new possibilities of the automated instrument as compared to the traditional ones are listed. The X-ray diffraction and fluorescence techniques can take advantage of the automation. (Author) [pt

  9. Hybrid Imaging Labels: Providing the Link Between Mass Spectrometry-Based Molecular Pathology and Theranostics

    Science.gov (United States)

    Buckle, Tessa; van der Wal, Steffen; van Malderen, Stijn J.M.; Müller, Larissa; Kuil, Joeri; van Unen, Vincent; Peters, Ruud J.B.; van Bemmel, Margaretha E.M.; McDonnell, Liam A.; Velders, Aldrik H.; Koning, Frits; Vanhaeke, Frank; van Leeuwen, Fijs W. B.

    2017-01-01

    Background: Development of theranostic concepts that include inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) imaging can be hindered by the lack of a direct comparison to more standardly used methods for in vitro and in vivo evaluation; e.g. fluorescence or nuclear medicine. In this study a bimodal (or rather, hybrid) tracer that contains both a fluorescent dye and a chelate was used to evaluate the existence of a direct link between mass spectrometry (MS) and in vitro and in vivo molecular imaging findings using fluorescence and radioisotopes. At the same time, the hybrid label was used to determine whether the use of a single isotope label would allow for MS-based diagnostics. Methods: A hybrid label that contained both a DTPA chelate (that was coordinated with either 165Ho or 111In) and a Cy5 fluorescent dye was coupled to the chemokine receptor 4 (CXCR4) targeting peptide Ac-TZ14011 (hybrid-Cy5-Ac-TZ4011). This receptor targeting tracer was used to 1) validate the efficacy of (165Ho-based) mass-cytometry in determining the receptor affinity via comparison with fluorescence-based flow cytometry (Cy5), 2) evaluate the microscopic binding pattern of the tracer in tumor cells using both fluorescence confocal imaging (Cy5) and LA-ICP-MS-imaging (165Ho), 3) compare in vivo biodistribution patterns obtained with ICP-MS (165Ho) and radiodetection (111In) after intravenous administration of hybrid-Cy5-Ac-TZ4011 in tumor-bearing mice. Finally, LA-ICP-MS-imaging (165Ho) was linked to fluorescence-based analysis of excised tissue samples (Cy5). Results: Analysis with both mass-cytometry and flow cytometry revealed a similar receptor affinity, respectively 352 ± 141 nM and 245 ± 65 nM (p = 0.08), but with a much lower detection sensitivity for the first modality. In vitro LA-ICP-MS imaging (165Ho) enabled clear discrimination between CXCR4 positive and negative cells, but fluorescence microscopy was required to determine the

  10. A fluorescence detection of D-penicillamine based on Cu(2+)-induced fluorescence quenching system of protein-stabilized gold nanoclusters.

    Science.gov (United States)

    Wang, Peng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

    2015-01-25

    In this contribution, a luminescent gold nanoclusters which were synthesized by bovine serum albumin as novel fluorescent probes were successfully utilized for the determination of D-penicillamine for the first time. Cupric ion was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of D-penicillamine caused obvious restoration of fluorescence intensity of the Cu(2+)-gold nanoclusters system. Under optimum conditions, the increment in fluorescence intensity of Cu(2+)-gold nanoclusters system caused by D-penicillamine was linearly proportional to the concentration of D-penicillamine in the range of 2.0×10(-5)-2.39×10(-4) M. The detection limit for D-penicillamine was 5.4×10(-6) M. With the off-on fluorescence signal at 650 nm approaching the near-infrared region, the present sensor for D-penicillamine detection had high sensitivity and low spectral interference. Furthermore, the novel gold nanoclusters-based fluorescent sensor has been applied to the determination of D-penicillamine in real biological samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Hyper-spectral modulation fluorescent imaging using double acousto-optical tunable filter based on TeO2-crystals

    International Nuclear Information System (INIS)

    Zaytsev, Kirill I; Perchik, Alexey V; Chernomyrdin, Nikita V; Yurchenko, Stanislav O; Kudrin, Konstantin G; Reshetov, Igor V

    2015-01-01

    We have proposed a method for hyper-spectral fluorescent imaging based on acousto-optical filtering. The object of interest was pumped using ultraviolet radiation of mercury lamp equipped with monochromatic excitation filter with the window of transparency centered at 365 nm. Double TeO 2 -based acousto-optical filter, tunable in range from 430 to 780 nm and having 2 nm bandwidth of spectral transparency, was used in order to detect quasimonochromatic images of object fluorescence. Modulating of ultraviolet pump intensity was used in order to reduce an impact of non-fluorescent background on the sample fluorescent imaging. The technique for signal-to-noise ratio improvement, based on fluorescence intensity estimation via digital processing of modulated video sequence of fluorescent object, was introduced. We have implemented the proposed technique for the test sample studying and we have discussed its possible applications

  12. Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

    Science.gov (United States)

    Wu, Ruixiang; Chen, Ruiyun; Zhou, Haitao; Qin, Yaqiang; Zhang, Guofeng; Qin, Chengbing; Gao, Yan; Gao, Yajun; Xiao, Liantuan; Jia, Suotang

    2018-01-01

    We present a sensitive method for detection of ultra-low oxygen concentrations based on the fluorescence blinking dynamics of single molecules. The relationship between the oxygen concentration and the fraction of time spent in the off-state, stemming from the population and depopulation of triplet states and radical cationic states, can be fitted with a two-site quenching model in the Stern-Volmer plot. The oxygen sensitivity is up to 43.42 kPa-1 in the oxygen partial pressure region as low as 0.01-0.25 kPa, which is seven times higher than that of the fluorescence intensity indicator. This method avoids the limitation of the sharp and non-ignorable fluctuations that occur during the measurement of fluorescence intensity, providing potential applications in the field of low oxygen-concentration monitoring in life science and industry.

  13. A new rhodamine-based fluorescent probe for the discrimination of Fe"3"+ from Fe"2"+

    International Nuclear Information System (INIS)

    You, Qi Hua; Huang, Hua Bin; Zhuang, Zhi Xia; Wang, Xiao Ru; Chan, Wing Hong

    2016-01-01

    A new rhodamine-based fluorescent probe for the discrimination of Fe"3"+ from Fe"2"+ has been designed and investigated. The probe shows an immediate visual color change in response to Fe"3"+ and Cu"2"+, while only Fe"3"+ triggers the fluorescent change of the probe. The existence of large amount of other metal ions shows negligible interference in the detection of Fe"3"+. The association constant K_a_s_s of 4.64 × 10"8 M"-"2 (R"2 = 0.994) and 5.38 × 10"8 M"-"2 (R"2 = 0.991) of the complex was derived from UV/Vis and fluorescence titration assuming 1:2 stoichiometry of probe–Fe"3"+ complex, respectively

  14. Dendrimer-based fluorescent indicators: in vitro and in vivo applications.

    Directory of Open Access Journals (Sweden)

    Lorenzo Albertazzi

    Full Text Available BACKGROUND: The development of fluorescent proteins and synthetic molecules whose fluorescence properties are controlled by the environment makes it possible to monitor physiological and pathological events in living systems with minimal perturbation. A large number of small organic dyes are available and routinely used to measure biologically relevant parameters. Unfortunately their application is hindered by a number of limitations stemming from the use of these small molecules in the biological environment. PRINCIPAL FINDINGS: We present a novel dendrimer-based architecture leading to multifunctional sensing elements that can overcome many of these problems. Applications in vitro, in living cells and in vivo are reported. In particular, we image for the first time extracellular pH in the brain in a mouse epilepsy model. CONCLUSION: We believe that the proposed architecture can represent a useful and novel tool in fluorescence imaging that can be widely applied in conjunction with a broad range of sensing dyes and experimental setups.

  15. A Fluorescent Thermometer Based on a Pyrene-Labeled Thermoresponsive Polymer

    Directory of Open Access Journals (Sweden)

    Ulrich S. Schubert

    2010-08-01

    Full Text Available Thermoresponsive polymers that undergo a solubility transition by variation of the temperature are important materials for the development of ‘smart’ materials. In this contribution we exploit the solubility phase transition of poly(methoxy diethylene glycol methacrylate, which is accompanied by a transition from hydrophilic to hydrophobic, for the development of a fluorescent thermometer. To translate the polymer phase transition into a fluorescent response, the polymer was functionalized with pyrene resulting in a change of the emission based on the microenvironment. This approach led to a soluble polymeric fluorescent thermometer with a temperature range from 11 °C to 21 °C. The polymer phase transition that occurs during sensing is studied in detail by dynamic light scattering.

  16. Improved efficiency of organic light-emitting diodes based on a europium complex by fluorescent dye

    Energy Technology Data Exchange (ETDEWEB)

    You Han [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China); Fang Junfeng [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China); Gao Jia [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China); Ma Dongge [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China)]. E-mail: mdg1014@ciac.jl.cn

    2007-01-15

    Improved efficiency of organic light-emitting diodes (OLEDs) based on europium complexes have been realized by using a fluorescent dye 4-(dicyanomethylene)-2-t-butyl-6 (1,1,7,7-tetramethyljulolidyl-9-enyl))-4H-pyran (DCJTB) doping .The luminous efficiency of the devices with a fluorescent dye in the emissive layer was found to improve two times of that in devices without fluorescent dye. The devices showed pure red light, which is the characteristic emission of trivalent europium ion with a full-width at half-maximum of 3 nm.The maximum brightness and luminous efficiency reached 1200 cd/m{sup 2} at 23 V and 7.3 cd/A (2.0 lm/w), respectively, at a current density of 0.35 mA/cm{sup 2}.

  17. Prospects of luminescence based molecular scale logic gates and logic circuits

    Energy Technology Data Exchange (ETDEWEB)

    Speiser, Shammai, E-mail: speiser@technion.ac.il

    2016-01-15

    In recent years molecular electronics has emerged as a rapidly growing research field. The aim of this review is to introduce this subject as a whole with special emphasis on molecular scale potential devices and applications. As a particular example we will discuss all optical molecular scale logic gates and logic circuits based on molecular fluorescence and electronic excitation transfer processes. Charge and electronic energy transfers (ET and EET) are well-studied examples whereby different molecules can signal their state from one (the donor, D) to the other (the acceptor, A). We show how a half-adder logic circuit can be implemented on one molecule that can communicate its logic output as input to another half-adder molecule. This is achieved as an electronic energy transfer from a donor to an acceptor, thus implementing a molecular full adder. We discuss a specific pair, the rhodamine–azulene, for which there is considerable spectroscopic data, but the scheme is general enough to allow a wide choice of D and A pairs. We present results based on this pair, in which, for the first time, an all optical half-adder and full-adder logic circuits are implemented. - Highlights: • Molecular scale logic • Photoquenching • Full adder.

  18. Prospects of luminescence based molecular scale logic gates and logic circuits

    International Nuclear Information System (INIS)

    Speiser, Shammai

    2016-01-01

    In recent years molecular electronics has emerged as a rapidly growing research field. The aim of this review is to introduce this subject as a whole with special emphasis on molecular scale potential devices and applications. As a particular example we will discuss all optical molecular scale logic gates and logic circuits based on molecular fluorescence and electronic excitation transfer processes. Charge and electronic energy transfers (ET and EET) are well-studied examples whereby different molecules can signal their state from one (the donor, D) to the other (the acceptor, A). We show how a half-adder logic circuit can be implemented on one molecule that can communicate its logic output as input to another half-adder molecule. This is achieved as an electronic energy transfer from a donor to an acceptor, thus implementing a molecular full adder. We discuss a specific pair, the rhodamine–azulene, for which there is considerable spectroscopic data, but the scheme is general enough to allow a wide choice of D and A pairs. We present results based on this pair, in which, for the first time, an all optical half-adder and full-adder logic circuits are implemented. - Highlights: • Molecular scale logic • Photoquenching • Full adder

  19. Design considerations for highly effective fluorescence excitation and detection optical systems for molecular diagnostics

    Science.gov (United States)

    Kasper, Axel; Van Hille, Herbert; Kuk, Sola

    2018-02-01

    Modern instruments for molecular diagnostics are continuously optimized for diagnostic accuracy, versatility and throughput. The latest progress in LED technology together with tailored optics solutions allows developing highly efficient photonics engines perfectly adapted to the sample under test. Super-bright chip-on-board LED light sources are a key component for such instruments providing maximum luminous intensities in a multitude of narrow spectral bands. In particular the combination of white LEDs with other narrow band LEDs allows achieving optimum efficiency outperforming traditional Xenon light sources in terms of energy consumption, heat dissipation in the system, and switching time between spectral channels. Maximum sensitivity of the diagnostic system can only be achieved with an optimized optics system for the illumination and imaging of the sample. The illumination beam path must be designed for optimum homogeneity across the field while precisely limiting the angular distribution of the excitation light. This is a necessity for avoiding spill-over to the detection beam path and guaranteeing the efficiency of the spectral filtering. The imaging optics must combine high spatial resolution, high light collection efficiency and optimized suppression of excitation light for good signal-to-noise ratio. In order to achieve minimum cross-talk between individual wells in the sample, the optics design must also consider the generation of stray light and the formation of ghost images. We discuss what parameters and limitations have to be considered in an integrated system design approach covering the full path from the light source to the detector.

  20. A nanoplasmonic switch based on molecular machines

    KAUST Repository

    Zheng, Yue Bing; Yang, Ying-Wei; Jensen, Lasse; Fang, Lei; Juluri, Bala Krishna; Weiss, Paul S.; Stoddart, J. Fraser; Huang, Tony Jun

    2009-01-01

    We aim to develop a molecular-machine-driven nanoplasmonic switch for its use in future nanophotonic integrated circuits (ICs) that have applications in optical communication, information processing, biological and chemical sensing. Experimental

  1. Molecular phylogeny of Ranunculaceae based on internal ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... evidence regarding the systematic classification of Ranunculaceae plants, we used molecular ... Ranunculaceae is a family of flowering plants known as ... and in the analysis of the evolutionary rate for lower level phylogeny ...

  2. A recombinant fusion protein-based, fluorescent protease assay for high throughput-compatible substrate screening.

    Science.gov (United States)

    Bozóki, Beáta; Gazda, Lívia; Tóth, Ferenc; Miczi, Márió; Mótyán, János András; Tőzsér, József

    2018-01-01

    In connection with the intensive investigation of proteases, several methods have been developed for analysis of the substrate specificity. Due to the great number of proteases and the expected target molecules to be analyzed, time- and cost-efficient high-throughput screening (HTS) methods are preferred. Here we describe the development and application of a separation-based HTS-compatible fluorescent protease assay, which is based on the use of recombinant fusion proteins as substrates of proteases. The protein substrates used in this assay consists of N-terminal (hexahistidine and maltose binding protein) fusion tags, cleavage sequences of the tobacco etch virus (TEV) and HIV-1 proteases, and a C-terminal fluorescent protein (mApple or mTurquoise2). The assay is based on the fluorimetric detection of the fluorescent proteins, which are released from the magnetic bead-attached substrates by the proteolytic cleavage. The protease assay has been applied for activity measurements of TEV and HIV-1 proteases to test the suitability of the system for enzyme kinetic measurements, inhibition studies, and determination of pH optimum. We also found that denatured fluorescent proteins can be renatured after SDS-PAGE of denaturing conditions, but showed differences in their renaturation abilities. After in-gel renaturation both substrates and cleavage products can be identified by in-gel UV detection. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Segmentation-based retrospective shading correction in fluorescence microscopy E. coli images for quantitative analysis

    Science.gov (United States)

    Mai, Fei; Chang, Chunqi; Liu, Wenqing; Xu, Weichao; Hung, Yeung S.

    2009-10-01

    Due to the inherent imperfections in the imaging process, fluorescence microscopy images often suffer from spurious intensity variations, which is usually referred to as intensity inhomogeneity, intensity non uniformity, shading or bias field. In this paper, a retrospective shading correction method for fluorescence microscopy Escherichia coli (E. Coli) images is proposed based on segmentation result. Segmentation and shading correction are coupled together, so we iteratively correct the shading effects based on segmentation result and refine the segmentation by segmenting the image after shading correction. A fluorescence microscopy E. Coli image can be segmented (based on its intensity value) into two classes: the background and the cells, where the intensity variation within each class is close to zero if there is no shading. Therefore, we make use of this characteristics to correct the shading in each iteration. Shading is mathematically modeled as a multiplicative component and an additive noise component. The additive component is removed by a denoising process, and the multiplicative component is estimated using a fast algorithm to minimize the intra-class intensity variation. We tested our method on synthetic images and real fluorescence E.coli images. It works well not only for visual inspection, but also for numerical evaluation. Our proposed method should be useful for further quantitative analysis especially for protein expression value comparison.

  4. Boundary fitting based segmentation of fluorescence microscopy images

    Science.gov (United States)

    Lee, Soonam; Salama, Paul; Dunn, Kenneth W.; Delp, Edward J.

    2015-03-01

    Segmentation is a fundamental step in quantifying characteristics, such as volume, shape, and orientation of cells and/or tissue. However, quantification of these characteristics still poses a challenge due to the unique properties of microscopy volumes. This paper proposes a 2D segmentation method that utilizes a combination of adaptive and global thresholding, potentials, z direction refinement, branch pruning, end point matching, and boundary fitting methods to delineate tubular objects in microscopy volumes. Experimental results demonstrate that the proposed method achieves better performance than an active contours based scheme.

  5. Fluorescently labeled bionanotransporters of nucleic acid based on carbon nanotubes

    International Nuclear Information System (INIS)

    Novopashina, D.S.; Apartsin, E.K.; Venyaminova, A.G.

    2012-01-01

    We propose an approach to the design of a new type of hybrids of oligonucleotides with fluorescein-functionalized single-walled carbon nanotubes. The approach is based on stacking interactions of functionalized nanotubes with pyrene residues in conjugates of oligonucleotides. The amino- and fluorescein-modified single walled carbon nanotubes are obtained, and their physico-chemical properties are investigated. The effect of the functionalization type of carbon nanotubes on the efficacy of the sorption of pyrene conjugates of oligonucleotides was examined. The proposed noncovalent hybrids of fluorescein-labeled carbon nanotubes with oligonucleotides may be used for the intracellular transport of functional nucleic acids.

  6. Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions.

    Science.gov (United States)

    Adams, Lori; Agrawal, Anoop; Cronin, John P; Ashley, Kevin

    2017-01-01

    Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1-3% (w˖w -1 ) aqueous ammonium bifluoride (NH 4 HF 2 ). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH 4 HF 2 solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels many-fold below those reported previously for this methodology. Notably, MDLs for Be of health organizations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly-designed occupational air sampler inserts are illustrated.

  7. Fluorescent silver nanoclusters capped by polyethyleneimine with different molecular weights: Universal synthesis and application as a temperature sensor

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Fei, E-mail: qufei3323@163.com [The Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165, Shandong (China); Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, Qufu Normal University, Qufu 273165, Shandong (China); Li, Qingjin [The Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165, Shandong (China); Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, Qufu Normal University, Qufu 273165, Shandong (China); You, Jinmao, E-mail: jmyou6304@163.com [The Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165, Shandong (China); Key Laboratory of Pharmaceutical Intermediates and Analysis of Natural Medicine, Qufu Normal University, Qufu 273165, Shandong (China); Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001 (China)

    2016-09-15

    In this paper, we developed a universal, applicable and simple synthetic method of Ag nanoclusters capped by polyethyleneimine (PEI) with different molecular weights (AgNC-PEIs), including Mw 600, 1300, 1800, 2000, 10,000, 25,000, 70,000, and 750,000. Using formaldehyde as the sole reducing agent, silver nanoclusters could be successfully prepared by using these templates. Subsequently, several characterization techniques were employed to investigate the properties of AgNC-PEIs, and the results suggested that these AgNC-PEIs had similar sizes, structures, and optical features. However, besides the common characteristics, different temperature sensitivities were found for these nanoclusters, in which AgNC-PEI 25000 was proper to be applied as a temperature sensor. With increasing temperature, the fluorescence quenched dramatically, and this change could be readily observed by naked eyes under UV light. Injection of these temperature sensitive nanoclusters into a glass tube, a simple thermometer could be fabricated easily, thus AgNC-PEI 25000 would be a promising candidate for temperature sensing as a visible indicator.

  8. Rapid molecular cytogenetic analysis of X-chromosomal microdeletions: Fluorescence in situ hybridization (FISH) for complex glycerol kinase deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Worley, K.C.; Lindsay, E.A.; McCabe, E.R.B. [Baylor College of Medicine, Houston, TX (United States)] [and others

    1995-07-17

    Diagnosis of X-chromosomal microdeletions has relied upon the traditional methods of Southern blotting and DNA amplification, with carrier identification requiring time-consuming and unreliable dosage calculations. In this report, we describe rapid molecular cytogenetic identification of deleted DNA in affected males with the Xp21 contiguous gene syndrome (complex glycerol kinase deficiency, CGKD) and female carriers for this disorder. CGKD deletions involve the genes for glycerol kinase, Duchenne muscular dystrophy, and/or adrenal hypoplasia congenita. We report an improved method for diagnosis of deletions in individuals with CGKD and for identification of female carriers within their families using fluorescence in situ hybridization (FISH) with a cosmid marker (cosmid 35) within the glycerol kinase gene. When used in combination with an Xq control probe, affected males demonstrate a single signal from the control probe, while female carriers demonstrate a normal chromosome with two signals, as well as a deleted chromosome with a single signal from the control probe. FISH analysis for CGKD provides the advantages of speed and accuracy for evaluation of submicroscopic X-chromosome deletions, particularly in identification of female carriers. In addition to improving carrier evaluation, FISH will make prenatal diagnosis of CGKD more readily available. 17 refs., 2 figs.

  9. A miniaturized oxygen sensor integrated on fiber surface based on evanescent-wave induced fluorescence quenching

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Yan [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Tan, Jun; Wang, Chengjie; Zhu, Ying [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Fang, Shenwen [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Wu, Jiayi; Wang, Qing [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Duan, Ming, E-mail: swpua124@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China); School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China)

    2016-11-15

    In this work, a miniaturized sensor was integrated on fiber surface and developed for oxygen determination through evanescent-wave induced fluorescence quenching. The sensor was designed by using light emitting diode (LED) as light source and optical fiber as light transmission element. Tris(2,2′-bipyridyl) ruthenium ([Ru(bpy){sub 3}]{sup 2+}) fluorophore was immobilized in the organically modified silicates (ORMOSILs) film and coated onto the fiber surface. When light propagated by total internal reflection (TIR) in the fiber core, evanescent wave could be produced on the fiber surface and excite [Ru(bpy){sub 3}]{sup 2+} fluorophore to produce fluorescence emission. Then oxygen could be determinated by its quenching effect on the fluorescence and its concentration could be evaluated according to Stern–Volumer model. Through integrating evanescent wave excitation and fluorescence quenching on fiber surface, the sensor was successfully miniaturized and exhibit improved performances of high sensitivity (1.4), excellent repeatability (1.2%) and fast analysis (12 s) for oxygen determination. The sensor provided a newly portable method for in-situ and real-time measurement of oxygen and showed potential for practical oxygen analysis in different application fields. Furthermore, the fabrication of this sensor provides a miniaturized and portable detection platform for species monitoring by simple modular design. - Highlights: • ORMOSILs sensing film immobilized with [Ru(bpy){sub 3}]{sup 2+} fluorophore was coated on fiber surface. • Evanescent wave on the fiber surface was utilized as excitation source to produce fluorescence. • Oxygen was measured based on its quenching effect on evanescent wave-induce fluorescence. • Sensor fabrication was miniaturized by integrating detection and sensing elements on the fiber. • The modular design sensor provides a detection platform for other species monitoring.

  10. Determination of Europium by fluorescence using pyrrolidinium based task specific ionic liquid

    International Nuclear Information System (INIS)

    Kumar, Satendra; Gayan, Siuli Maji; Sankaran, K.

    2012-01-01

    Determination of lanthanides using fluorescence is a major challenge in aqueous medium due to their poor molar absorptivities and low quantum yield. To overcome these problems, ligand sensitized fluorescence has been widely used for trace level detection of lanthanides in solutions. Recently, ionic liquid a non aqueous medium has been used to observe the fluorescence of lanthanides. In this work we have used pyrrolidinium based ionic liquid for the study of europium fluorescence. The ionic liquid (bmpyr)(BA) was prepared using the metathesis reaction involving 1-butyl,1-methyl pyrrolidinium chloride (bmpyr)(CI). (bmpyr)(Cl) crystals and silver benzoate were added according to their mole equivalents in methanol and stirred for 4 hrs. The filtrate was concentrated using a rotary evaporator, dried for 10 h at room temperature, and then for 40 h at 105℃under reduced pressure. This results in a white crystalline hygroscopic solid which was characterized by FT-lR spectroscopy. The yield of the product was ∼ 95%. Butyl-1, methyl pyrrolidinium bis(trifluoromethanesulfonyl)amide (bmpyr)(TF 2 N) is used for dissolve and dilute (bmpyr)(BA) and fluorescence and life time of Eu 3+ were obtained. For the concentration of Eu 3+ used in this study (2x10 -7 M), the optimum concentration of the sensitizing ionic liquid was found to be 10 -4 M. An enhancement factor of about 32000 was found in this ionic liquid compare to aqueous medium. Fluorescence life time of europium in this ionic liquid is 1100 μs which is ten times more than the life time of europium in aqueous medium (110 μs), indicating a reduction in the rates of non-radiative processes which was provided by the ionic liquid. This study leads to detection of europium in ppb level. (author)

  11. Fluorescence-based detection of nitric oxide in aqueous and methanol media using a copper(II) complex.

    Science.gov (United States)

    Mondal, Biplab; Kumar, Pankaj; Ghosh, Pokhraj; Kalita, Apurba

    2011-03-14

    The quenched fluorescent intensity of a copper(II) complex, 1, of a fluorescent ligand, in degassed methanol or aqueous (buffered at pH 7.2) solution, was found to reappear on exposure to nitric oxide. Thus, it can function as a fluorescence based nitric oxide sensor. It has been found that the present complex can be used to sense nanomolar quantities of nitric oxide in both methanol and pH 7.2 buffered-water medium.

  12. Spectral ’Fingerprinting’ of Phytoplankton Populations by Two-Dimensional Fluorescence and Fourier-Transform-Based Pattern Recognition.

    Science.gov (United States)

    1985-07-08

    Chlorella vulgaris and Aaphidinium carterae ) were synthetically added to each other in varying proportions from 0% C. vulgaris fluorescence to 100...C. vulgaris fluorescence in 10% increments. The proportions were calculated based on the maximum fluorescence intensity. The series of mixtures was...then correlated against the original 9 standard library in which the C. vulgaris and A. Carterae REs were represented. Table IV presents the results of

  13. Photocured thiol-ene based optical fluorescence sensor for determination of gold(III)

    Energy Technology Data Exchange (ETDEWEB)

    Çubuk, Soner, E-mail: sonercubuk@marmara.edu.tr; Kahraman, Memet Vezir; Yetimoğlu, Ece Kök; Kenan, Sibel

    2014-02-17

    Graphical abstract: -- Highlights: •Photopolymerized fluorescence sensor for Au(III) analysis has been developed. •Preparation of polymeric sensor is simple and quick. •Fluorescence sensor used for analysis of Au(III) in real samples. -- Abstract: This study describes the preparation and the characterization of a new thiol-ene based polymeric fluorescence sensor by photo initiated polymerization of trimethylolpropane tris(3-mercaptopropionate), 2-hydroxyethylacrylate, and 2,4,6-triallyloxy-1,3,5-triazine which are used as monomers and also a photo initiator (2,2-dimethoxy-2-phenylacetophenone) for its usage as optical sensor for gold ions. The thiol-ene based polymeric membrane sensor was characterized by using attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). The response characteristics of the sensors including dynamic range, pH effect, response time, and the effect of foreign ions were investigated. Fluorescence spectra showed that the excitation/emission maxima of the membrane were at 379/425 nm, respectively.

  14. Fluorescence-based Western blotting for quantitation of protein biomarkers in clinical samples.

    Science.gov (United States)

    Zellner, Maria; Babeluk, Rita; Diestinger, Michael; Pirchegger, Petra; Skeledzic, Senada; Oehler, Rudolf

    2008-09-01

    Since most high throughput techniques used in biomarker discovery are very time and cost intensive, highly specific and quantitative analytical alternative application methods are needed for the routine analysis. Conventional Western blotting allows detection of specific proteins to the level of single isotypes while its quantitative accuracy is rather limited. We report a novel and improved quantitative Western blotting method. The use of fluorescently labelled secondary antibodies strongly extends the dynamic range of the quantitation and improves the correlation with the protein amount (r=0.997). By an additional fluorescent staining of all proteins immediately after their transfer to the blot membrane, it is possible to visualise simultaneously the antibody binding and the total protein profile. This allows for an accurate correction for protein load. Applying this normalisation it could be demonstrated that fluorescence-based Western blotting is able to reproduce a quantitative analysis of two specific proteins in blood platelet samples from 44 subjects with different diseases as initially conducted by 2D-DIGE. These results show that the proposed fluorescence-based Western blotting is an adequate application technique for biomarker quantitation and suggest possibilities of employment that go far beyond.

  15. Triphenylamine based benzimidazole and benzothiazole: Synthesis and applications in fluorescent chemosensors and laser dyes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Li, Bin, E-mail: libinteacher@163.com [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Zhang, Liming; Guan, Yunlong [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

    2014-01-15

    Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. The TPA-benzimidazole chemosensor was tested for a number of metal ions and found to exhibit binding affinity for Fe{sup 3+} and Hg{sup 2+} in acetonitrile, and the fluorescence quenching was achieved through a PET process. The appearance of an isosbestic point in absorption titrations and Job's plot analysis supported 1:1 stoichiometries for Fe{sup 3+} and Hg{sup 2+} ions. Laser experiments showed that under transversal pumping with a Q-switched Nd:YAG (355 nm) laser in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) at 436 nm. -- Highlights: • Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. • The TPA-benzimidazole exhibits binding affinity for Fe{sup 3+} and Hg{sup 2+} in acetonitrile and the fluorescence quenching was achieved through a PET process. • Under transversal pumping at 355 nm in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) in 436 nm.

  16. A novel acidic pH fluorescent probe based on a benzothiazole derivative

    Science.gov (United States)

    Ma, Qiujuan; Li, Xian; Feng, Suxiang; Liang, Beibei; Zhou, Tiqiang; Xu, Min; Ma, Zhuoyi

    2017-04-01

    A novel acidic pH fluorescent probe 1 based on a benzothiazole derivative has been designed, synthesized and developed. The linear response range covers the acidic pH range from 3.44 to 6.46, which is valuable for pH researches in acidic environment. The evaluated pKa value of the probe 1 is 4.23. The fluorescence enhancement of the studied probe 1 with an increase in hydrogen ions concentration is based on the hindering of enhanced photo-induced electron transfer (PET) process. Moreover, the pH sensor possesses a highly selective response to H+ in the presence of metal ions, anions and other bioactive small molecules which would be interfere with its fluorescent pH response. Furthermore, the probe 1 responds to acidic pH with short response time that was less than 1 min. The probe 1 has been successfully applied to confocal fluorescence imaging in live HeLa cells and can selectively stain lysosomes. All of such good properties prove it can be used to monitoring pH fluctuations in acidic environment with high sensitivity, pH dependence and short response time.

  17. Fluoromodule-based reporter/probes designed for in vivo fluorescence imaging

    Science.gov (United States)

    Zhang, Ming; Chakraborty, Subhasish K.; Sampath, Padma; Rojas, Juan J.; Hou, Weizhou; Saurabh, Saumya; Thorne, Steve H.; Bruchez, Marcel P.; Waggoner, Alan S.

    2015-01-01

    Optical imaging of whole, living animals has proven to be a powerful tool in multiple areas of preclinical research and has allowed noninvasive monitoring of immune responses, tumor and pathogen growth, and treatment responses in longitudinal studies. However, fluorescence-based studies in animals are challenging because tissue absorbs and autofluoresces strongly in the visible light spectrum. These optical properties drive development and use of fluorescent labels that absorb and emit at longer wavelengths. Here, we present a far-red absorbing fluoromodule–based reporter/probe system and show that this system can be used for imaging in living mice. The probe we developed is a fluorogenic dye called SC1 that is dark in solution but highly fluorescent when bound to its cognate reporter, Mars1. The reporter/probe complex, or fluoromodule, produced peak emission near 730 nm. Mars1 was able to bind a variety of structurally similar probes that differ in color and membrane permeability. We demonstrated that a tool kit of multiple probes can be used to label extracellular and intracellular reporter–tagged receptor pools with 2 colors. Imaging studies may benefit from this far-red excited reporter/probe system, which features tight coupling between probe fluorescence and reporter binding and offers the option of using an expandable family of fluorogenic probes with a single reporter gene. PMID:26348895

  18. Photocured thiol-ene based optical fluorescence sensor for determination of gold(III)

    International Nuclear Information System (INIS)

    Çubuk, Soner; Kahraman, Memet Vezir; Yetimoğlu, Ece Kök; Kenan, Sibel

    2014-01-01

    Graphical abstract: -- Highlights: •Photopolymerized fluorescence sensor for Au(III) analysis has been developed. •Preparation of polymeric sensor is simple and quick. •Fluorescence sensor used for analysis of Au(III) in real samples. -- Abstract: This study describes the preparation and the characterization of a new thiol-ene based polymeric fluorescence sensor by photo initiated polymerization of trimethylolpropane tris(3-mercaptopropionate), 2-hydroxyethylacrylate, and 2,4,6-triallyloxy-1,3,5-triazine which are used as monomers and also a photo initiator (2,2-dimethoxy-2-phenylacetophenone) for its usage as optical sensor for gold ions. The thiol-ene based polymeric membrane sensor was characterized by using attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). The response characteristics of the sensors including dynamic range, pH effect, response time, and the effect of foreign ions were investigated. Fluorescence spectra showed that the excitation/emission maxima of the membrane were at 379/425 nm, respectively

  19. Organic fluorescent dye-based nanomaterials: Advances in the rational design for imaging and sensing applications.

    Science.gov (United States)

    Svechkarev, Denis; Mohs, Aaron M

    2018-02-25

    Self-assembled fluorescent nanomaterials based on small-molecule organic dyes are gaining increasing popularity in imaging and sensing applications over the past decade. This is primarily due to their ability to combine spectral property tunability and biocompatibility of small molecule organic fluorophores with brightness, chemical, and colloidal stability of inorganic materials. Such a unique combination of features comes with rich versatility of dye-based nanomaterials: from aggregates of small molecules to sophisticated core-shell nanoarchitectures involving hyperbranched polymers. Along with the ongoing discovery of new materials and better ways of their synthesis, it is very important to continue systematic studies of fundamental factors that regulate the key properties of fluorescent nanomaterials: their size, polydispersity, colloidal stability, chemical stability, absorption and emission maxima, biocompatibility, and interactions with biological interfaces. In this review, we focus on the systematic description of various types of organic fluorescent nanomaterials, approaches to their synthesis, and ways to optimize and control their characteristics. The discussion is built on examples from reports on recent advances in design and applications of such materials. Conclusions made from this analysis allow a perspective on future development of fluorescent nanomaterials design for biomedical and related applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. Fluorescent Biosensor for Phosphate Determination Based on Immobilized Polyfluorene-Liposomal Nanoparticles Coupled with Alkaline Phosphatase.

    Science.gov (United States)

    Kahveci, Zehra; Martínez-Tomé, Maria José; Mallavia, Ricardo; Mateo, C Reyes

    2017-01-11

    This work describes the development of a novel fluorescent biosensor based on the inhibition of alkaline phosphatase (ALP). The biosensor is composed of the enzyme ALP and the conjugated cationic polyfluorene HTMA-PFP. The working principle of the biosensor is based on the fluorescence quenching of this polyelectrolyte by p-nitrophenol (PNP), a product of the hydrolysis reaction of p-nitrophenyl phosphate (PNPP) catalyzed by ALP. Because HTMA-PFP forms unstable aggregates in buffer, with low fluorescence efficiency, previous stabilization of the polyelectrolyte was required before the development of the biosensor. HTMA-PFP was stabilized through its interaction with lipid vesicles to obtain stable blue-emitting nanoparticles (NPs). Fluorescent NPs were characterized, and the ability to be quenched by PNP was evaluated. These nanoparticles were coupled to ALP and entrapped in a sol-gel matrix to produce a biosensor that can serve as a screening platform to identify ALP inhibitors. The components of the biosensor were examined before and after sol-gel entrapment, and the biosensor was optimized to allow the determination of phosphate ion in aqueous medium.

  1. Triphenylamine based benzimidazole and benzothiazole: Synthesis and applications in fluorescent chemosensors and laser dyes

    International Nuclear Information System (INIS)

    Yang, Yang; Li, Bin; Zhang, Liming; Guan, Yunlong

    2014-01-01

    Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. The TPA-benzimidazole chemosensor was tested for a number of metal ions and found to exhibit binding affinity for Fe 3+ and Hg 2+ in acetonitrile, and the fluorescence quenching was achieved through a PET process. The appearance of an isosbestic point in absorption titrations and Job's plot analysis supported 1:1 stoichiometries for Fe 3+ and Hg 2+ ions. Laser experiments showed that under transversal pumping with a Q-switched Nd:YAG (355 nm) laser in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) at 436 nm. -- Highlights: • Triphenylamine based fluorescent dyes TPA-benzimidazole and TPA-benzothiazole have been designed and synthesized. • The TPA-benzimidazole exhibits binding affinity for Fe 3+ and Hg 2+ in acetonitrile and the fluorescence quenching was achieved through a PET process. • Under transversal pumping at 355 nm in toluene, TPA-benzothiazole exhibits efficient and stable amplified spontaneous emissions (ASE) in 436 nm

  2. The Design of a Molecular Assembly Line Based on Biological Molecules

    Science.gov (United States)

    2003-06-01

    parenthesis in figure 1.8 is a bi-stable toggle switch. Introduction: Molecular assembly lines O=P-O- O O HOH H0P-0- O -O- 4 Polymerase HO H--- O HHO ...sample. Therefore, the samples are self-consistent. From here on, the calculated temperature based on FAM emission MNSowmm" RF Biology: Results and...irradiation for one hour. Figure 2.11 shows the fluorescence spectra of FAM emission (4 scans averaged over 200 seconds) in a 300MHz field. The increased

  3. CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel.

    Science.gov (United States)

    Tokuda, Takashi; Takahashi, Masayuki; Uejima, Kazuhiro; Masuda, Keita; Kawamura, Toshikazu; Ohta, Yasumi; Motoyama, Mayumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Okitsu, Teru; Takeuchi, Shoji; Ohta, Jun

    2014-11-01

    A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments.

  4. Lifetime-based optical sensor for high-level pCO2 detection employing fluorescence resonance energy transfer

    International Nuclear Information System (INIS)

    Bueltzingsloewen, Christoph von; McEvoy, Aisling K.; McDonagh, Colette; MacCraith, Brian D.

    2003-01-01

    An optical sensor for the measurement of high levels of carbon dioxide in gas phase has been developed. It is based on fluorescence resonance energy transfer (FRET) between a long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye are both immobilised in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix material. Tetraoctylammonium hydroxide (TOA-OH) is used as an internal buffering system. Fluorescence lifetime is measured in the frequency domain, using low-cost phase modulation measurement technology. The use of Sudan III as an acceptor dye has enabled the sensor to have a dynamic range up to 100% carbon dioxide. The sensor displays 11.2 deg. phase shift between the limit of detection (LOD) of 0.06 and 100% CO 2 with a resolution of better than 2%. The encapsulation in the silica/polymer hybrid material has provided the sensor with good mechanical and chemical stability. The effect of molecular oxygen, humidity and temperature on the sensor performance was studied in detail

  5. Multivalent calix[4]arene-based fluorescent sensor for detecting silver ions in aqueous media and physiological environment.

    Science.gov (United States)

    Lotfi, Behzad; Tarlani, Aliakbar; Akbari-Moghaddam, Peyman; Mirza-Aghayan, Maryam; Peyghan, Ali Ahmadi; Muzart, Jacques; Zadmard, Reza

    2017-04-15

    A new derivative of dipodal 1,3-calix[4]arene-based chemosensor (R), which was containing several binding sites have been synthesized and characterized by NMR, IR and LC-MS spectroscopic methods. The selectivity of Rhas been investigated in aqueous methanol, resulting in fluorescence shift and selective recognition of Ag + among 20 various alkali, alkaline earth and transition metal ions. Microstructural features of R and its complex with Ag + have been investigated by Atomic Force Microscopy (AFM). AFM images can clearly differentiate R from its complex of Ag + . Moreover; the complicated binding mode of metal-ligand complex has been explored by UV-Vis, LC-MS, FIR, Fluorescence titration, Job's plot method and theoretical approaches. Density functional theory (DFT) method at B3LYP/LANL2DZ level of theory was employed for computational studies. Theoretical calculations revealed that selectivity and specificity of R toward Ag + could be attributed to structural conformation of 1,3-alternate-calix[4]arene scaffold and molecular electrostatic potential of its surface. Furthermore; the competitive experiments were carried out to test sensor's ability for practical uses. Finally, the efficiency of R in matrix of physiological cations was examined and showed gradual emission enhancement which makes R an ideal candidate for monitoring of Ag + in physiological environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Logic circuits based on molecular spider systems.

    Science.gov (United States)

    Mo, Dandan; Lakin, Matthew R; Stefanovic, Darko

    2016-08-01

    Spatial locality brings the advantages of computation speed-up and sequence reuse to molecular computing. In particular, molecular walkers that undergo localized reactions are of interest for implementing logic computations at the nanoscale. We use molecular spider walkers to implement logic circuits. We develop an extended multi-spider model with a dynamic environment wherein signal transmission is triggered via localized reactions, and use this model to implement three basic gates (AND, OR, NOT) and a cascading mechanism. We develop an algorithm to automatically generate the layout of the circuit. We use a kinetic Monte Carlo algorithm to simulate circuit computations, and we analyze circuit complexity: our design scales linearly with formula size and has a logarithmic time complexity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Monitoring of chlorsulfuron in biological fluids and water samples by molecular fluorescence using rhodamine B as fluorophore.

    Science.gov (United States)

    Alesso, Magdalena; Escudero, Luis A; Talio, María Carolina; Fernández, Liliana P

    2016-11-01

    A new simple methodology is proposed for chlorsufuron (CS) traces quantification based upon enhancement of rhodamine B (RhB) fluorescent signal. Experimental variables that influence fluorimetric sensitivity have been studied and optimized. The zeroth order regression calibration was linear from 0.866 to 35.800µgL(-1) CS, with a correlation coefficient of 0.99. At optimal experimental conditions, a limit of detection of 0.259µgL(-1) and a limit of quantification of 0.866µgL(-1) were obtained. The method showed good sensitivity and adequate selectivity and was applied to the determination of trace amounts of CS in plasma, serum and water samples with satisfactory results analyzed by ANOVA test. The proposed methodology represents an alternative to traditional chromatographic techniques for CS monitoring in complex samples, using an accessible instrument in control laboratories. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Investigation of molecular mechanisms of action of chelating drugs on protein-lipid model membranes by X-ray fluorescence

    International Nuclear Information System (INIS)

    Novikova, N. N.; Zheludeva, S. I.; Koval'chuk, M. V.; Stepina, N. D.; Erko, A. I.; Yur'eva, E. A.

    2009-01-01

    Protein-lipid films based on the enzyme alkaline phosphatase were subjected to the action of chelating drugs, which are used for accelerating the removal of heavy metals from the human body, and the elemental composition of the resulting films was investigated. Total-reflection X-ray fluorescence measurements were performed at the Berlin Electron Storage Ring Company for Synchrotron Radiation (BESSY) in Germany. A comparative estimation of the protective effect of four drugs (EDTA, succimer, xydiphone, and mediphon) on membrane-bound enzymes damaged by lead ions was made. The changes in the elemental composition of the protein-lipid films caused by high doses of chelating drugs were investigated. It was shown that state-of-the-art X-ray techniques can, in principle, be used to develop new methods for the in vitro evaluation of the efficiency of drugs, providing differential data on their actions.

  9. Hybrid Microfluidic Platform for Multifactorial Analysis Based on Electrical Impedance, Refractometry, Optical Absorption and Fluorescence

    Directory of Open Access Journals (Sweden)

    Fábio M. Pereira

    2016-10-01

    Full Text Available This paper describes the development of a novel microfluidic platform for multifactorial analysis integrating four label-free detection methods: electrical impedance, refractometry, optical absorption and fluorescence. We present the rationale for the design and the details of the microfabrication of this multifactorial hybrid microfluidic chip. The structure of the platform consists of a three-dimensionally patterned polydimethylsiloxane top part attached to a bottom SU-8 epoxy-based negative photoresist part, where microelectrodes and optical fibers are incorporated to enable impedance and optical analysis. As a proof of concept, the chip functions have been tested and explored, enabling a diversity of applications: (i impedance-based identification of the size of micro beads, as well as counting and distinguishing of erythrocytes by their volume or membrane properties; (ii simultaneous determination of the refractive index and optical absorption properties of solutions; and (iii fluorescence-based bead counting.

  10. A fluorescent sensor based on binaphthol-quinoline Schiff base for ...

    Indian Academy of Sciences (India)

    est in developing selective and sensitive Zn2+ sensors to recognize the physiological ... tion of oxalate has received substantial attention due to its simplicity and waiver .... and isophthalate caused no significant fluorescence spectrum changes ...

  11. Hydrogen sulfide deactivates common nitrobenzofurazan-based fluorescent thiol labeling reagents.

    Science.gov (United States)

    Montoya, Leticia A; Pluth, Michael D

    2014-06-17

    Sulfhydryl-containing compounds, including thiols and hydrogen sulfide (H2S), play important but differential roles in biological structure and function. One major challenge in separating the biological roles of thiols and H2S is developing tools to effectively separate the reactivity of these sulfhydryl-containing compounds. To address this challenge, we report the differential responses of common electrophilic fluorescent thiol labeling reagents, including nitrobenzofurazan-based scaffolds, maleimides, alkylating agents, and electrophilic aldehydes, toward cysteine and H2S. Although H2S reacted with all of the investigated scaffolds, the photophysical response to each scaffold was significantly different. Maleimide-based, alkylating, and aldehydic thiol labeling reagents provided a diminished fluorescence response when treated with H2S. By contrast, nitrobenzofurazan-based labeling reagents were deactivated by H2S addition. Furthermore, the addition of H2S to thiol-activated nitrobenzofurazan-based reagents reduced the fluorescence signal, thus establishing the incompatibility of nitrobenzofurazan-based thiol labeling reagents in the presence of H2S. Taken together, these studies highlight the differential reactivity of thiols and H2S toward common thiol-labeling reagents and suggest that sufficient care must be taken when labeling or measuring thiols in cellular environments that produce H2S due to the potential for both false-positive and eroded responses.

  12. Cyclin B1 Destruction Box-Mediated Protein Instability: The Enhanced Sensitivity of Fluorescent-Protein-Based Reporter Gene System

    Directory of Open Access Journals (Sweden)

    Chao-Hsun Yang

    2013-01-01

    Full Text Available The periodic expression and destruction of several cyclins are the most important steps for the exact regulation of cell cycle. Cyclins are degraded by the ubiquitin-proteasome system during cell cycle. Besides, a short sequence near the N-terminal of cyclin B called the destruction box (D-box; CDB is also required. Fluorescent-protein-based reporter gene system is insensitive to analysis because of the overly stable fluorescent proteins. Therefore, in this study, we use human CDB fused with both enhanced green fluorescent protein (EGFP at C-terminus and red fluorescent protein (RFP, DsRed at N-terminus in the transfected human melanoma cells to examine the effects of CDB on different fluorescent proteins. Our results indicated that CDB-fused fluorescent protein can be used to examine the slight gene regulations in the reporter gene system and have the potential to be the system for screening of functional compounds in the future.

  13. Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-Phenylenediamine in presence of bile acid host

    Science.gov (United States)

    Roy, Nayan; Paul, Pradip C.; Singh, T. Sanjoy

    2015-05-01

    Fluorescence properties of Schiff base - N,N‧-bis(salicylidene) - 1,2-phenylenediamine (LH2) is used to study the micelles formed by aggregation of different important bile acids like cholic acid, deoxycholic acid, chenodeoxycholic acid and glycocholic acid by steady state and picosecond time-resolved fluorescence spectroscopy. The fluorescence band intensity was found out to increase with concomitant red shift with gradual addition of different bile acids. Binding constant of the probe with different bile acids as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of bile acids in the medium. The increase in fluorescence quantum yields, fluorescence decay times and substantial decrease in nonradiative decay rate constants in bile acids micellar environment points to the restricted motion of the fluorophore inside the micellar subdomains.

  14. A simple fluorescence based assay for quantification of human immunodeficiency virus particle release

    Directory of Open Access Journals (Sweden)

    Heuser Anke-Mareil

    2010-04-01

    Full Text Available Abstract Background The assembly and release of human immunodeficiency virus (HIV particles from infected cells represent attractive, but not yet exploited targets for antiretroviral therapy. The availability of simple methods to measure the efficiency of these replication steps in tissue culture would facilitate the identification of host factors essential for these processes as well as the screening for lead compounds acting as specific inhibitors of particle formation. We describe here the development of a rapid cell based assay for quantification of human immunodeficiency virus type 1 (HIV-1 particle assembly and/or release. Results Using a fluorescently labelled HIV-derivative, which carries an eYFP domain within the main viral structural protein Gag in the complete viral protein context, the release of virus like particles could be monitored by directly measuring the fluorescence intensity of the tissue culture supernatant. Intracellular Gag was quantitated in parallel by direct fluorescence analysis of cell lysates, allowing us to normalize for Gag expression efficiency. The assay was validated by comparison with p24 capsid ELISA measurements, a standard method for quantifying HIV-1 particles. Optimization of conditions allowed the robust detection of particle amounts corresponding to 50 ng p24/ml in medium by fluorescence spectroscopy. Further adaptation to a multi-well format rendered the assay suitable for medium or high throughput screening of siRNA libraries to identify host cell factors involved in late stages of HIV replication, as well as for random screening approaches to search for potential inhibitors of HIV-1 assembly or release. Conclusions The fast and simple fluorescence based quantification of HIV particle release yielded reproducible results which were comparable to the well established ELISA measurements, while in addition allowing the parallel determination of intracellular Gag expression. The protocols described here

  15. Piezoelectric sensors based on molecular imprinted polymers for detection of low molecular mass analytes.

    Science.gov (United States)

    Uludağ, Yildiz; Piletsky, Sergey A; Turner, Anthony P F; Cooper, Matthew A

    2007-11-01

    Biomimetic recognition elements employed for the detection of analytes are commonly based on proteinaceous affibodies, immunoglobulins, single-chain and single-domain antibody fragments or aptamers. The alternative supra-molecular approach using a molecularly imprinted polymer now has proven utility in numerous applications ranging from liquid chromatography to bioassays. Despite inherent advantages compared with biochemical/biological recognition (which include robustness, storage endurance and lower costs) there are few contributions that describe quantitative analytical applications of molecularly imprinted polymers for relevant small molecular mass compounds in real-world samples. There is, however, significant literature describing the use of low-power, portable piezoelectric transducers to detect analytes in environmental monitoring and other application areas. Here we review the combination of molecularly imprinted polymers as recognition elements with piezoelectric biosensors for quantitative detection of small molecules. Analytes are classified by type and sample matrix presentation and various molecularly imprinted polymer synthetic fabrication strategies are also reviewed.

  16. Two colorimetric and ratiometric fluorescence probes for hydrogen sulfide based on AIE strategy of α-cyanostilbenes

    Science.gov (United States)

    Zhao, Baoying; Yang, Binsheng; Hu, Xiangquan; Liu, Bin

    2018-06-01

    Aggregation-induced emission (AIE) active fluorescent probes have attracted great potential in biological sensors. In this paper two cyanostilbene based fluorescence chemoprobe Cya-NO2 (1) and Cya-N3 (2) were developed and evaluated for the selective and sensitive detection of hydrogen sulfide (H2S). Both of these probes behave aggression-induced emission (AIE) activity which fluoresces in the red region with a large Stokes shift. They exhibit rapid response to H2S with enormous colorimetric and ratiometric fluorescent changes. They are readily employed for assessing intracellular H2S levels.

  17. Novel Schiff Bases Based on the Quinolinone Skeleton: Syntheses, X-ray Structures and Fluorescent Properties

    Directory of Open Access Journals (Sweden)

    Zdeněk Trávníček

    2014-09-01

    Full Text Available A series of a new type of Schiff bases 1–7, derived from 2-phenyl-3-amino-4(1H-quinolinone and R-salicyladehyde derivatives wherein R = 3-hydroxy (1, 3,4-dihydroxy (2, 3-methoxy (3, 3-carboxy (4, 3-allyl (5, 5-chloro (6, and 5-nitro (7, was synthesized and structurally characterized. Each of the molecules 1, 3 and 7 consists of three planar moieties (i.e., a quinolinone and two phenyl rings, which are mutually oriented differently depending on the appropriate substituent R and the extent of non-covalent contacts stabilizing the crystal structures. The compounds were studied for their fluorescence properties, where compound 6 yielded the strongest intensity both in the solid phase and in 100 μM ethanol solution with a quantum yield of φ = 3.6% as compared to quinine sulfate used as a standard. The in vitro cytotoxicity of these compounds was tested against the human osteosarcoma (HOS and breast adenocarcinoma (MCF7 cell lines, revealing no activity up to the concentration of 50 µM.

  18. Fluorescent sensors for selective detection of thiols: expanding the intramolecular displacement based mechanism to new chromophores.

    Science.gov (United States)

    Niu, Li-Ya; Zheng, Hai-Rong; Chen, Yu-Zhe; Wu, Li-Zhu; Tung, Chen-Ho; Yang, Qing-Zheng

    2014-03-21

    Biological thiols, including cysteine (Cys), homocystein (Hcy) and glutathione (GSH), play crucial roles in maintaining the appropriate redox status of biological systems. An abnormal level of biothiols is associated with different diseases, therefore, the discrimination between them is of great importance. Herein, we present two fluorescent sensors for selective detection of biothiols based on our recently reported intramolecular displacement mechanism. We expanded this mechanism to commercially available chromophores, 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) and heptamethine cyanine dye IR-780. The sensors operate by undergoing displacement of chloride by thiolate. The amino groups of Cys/Hcy further replace the thiolate to form amino-substituted products, which exhibit dramatically different photophysical properties compared to sulfur-substituted products from the reaction with GSH. NBD-Cl is highly selective towards Cys/Hcy and exhibits significant fluorescence enhancement. IR-780 showed a variation in its fluorescence ratio towards Cys over other thiols. Both of the sensors can be used for live-cell imaging of Cys. The wide applicability of the mechanism may provide a powerful tool for developing novel fluorescent sensors for selective detection of biothiols.

  19. Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid

    Science.gov (United States)

    Lin, Haitao; Ding, Liyun; Zhang, Bingyu; Huang, Jun

    2018-05-01

    A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern-Volmer equation (I0/I - 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

  20. Determination of adenine based on the fluorescence recovery of the L-Tryptophan-Cu(2+) complex.

    Science.gov (United States)

    Duan, Ruilin; Li, Chunyan; Liu, Shaopu; Liu, Zhongfang; Li, Yuanfang; Yuan, Yusheng; Hu, Xiaoli

    2016-01-05

    A simple and sensitive method for determination of adenine was developed based on fluorescence quenching and recovery of L-Tryptophan (L-Trp). The fluorescence of L-Trp could efficiently quenched by copper ion compared with other common metal ions. Upon addition of adenine (Ade) in L-Trp-Cu(II) system, the fluorescence was reoccurred. Under the optimum conditions, the recovery fluorescence intensity was linearly correlated with the concentration of adenine in the range from 0.34 to 25.0μmolL(-1), with a correlation coefficient (R(2)) of 0.9994. The detection limit (3σ/k) was 0.046μmolL(-1), indicating that this method could applied to detect trace adenine. In this study, amino acids including L-Trp, D-Trp, L-Tyr, D-Tyr, L-Phe, D-Phe were investigated and only L-Trp could well chelated copper ion. Additionally, the mechanism of quench and recovery also were discussed and the method was successfully applied to detect the adenine in DNA with satisfactory results. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Fluorescent carbon nanoparticle-based lateral flow biosensor for ultrasensitive detection of DNA.

    Science.gov (United States)

    Takalkar, Sunitha; Baryeh, Kwaku; Liu, Guodong

    2017-12-15

    We report a fluorescent carbon nanoparticle (FCN)-based lateral flow biosensor for ultrasensitive detection of DNA. Fluorescent carbon nanoparticle with a diameter of around 15nm was used as a tag to label a detection DNA probe, which was complementary with the part of target DNA. A capture DNA probe was immobilized on the test zone of the lateral flow biosensor. Sandwich-type hybridization reactions among the FCN-labeled DNA probe, target DNA and capture DNA probe were performed on the lateral flow biosensor. In the presence of target DNA, FCNs were captured on the test zone of the biosensor and the fluorescent intensity of the captured FCNs was measured with a portable fluorescent reader. After systematic optimizations of experimental parameters (the components of running buffers, the concentration of detection DNA probe used in the preparation of FCN-DNA conjugates, the amount of FCN-DNA dispensed on the conjugate pad and the dispensing cycles of the capture DNA probes on the test-zone), the biosensor could detect a minimum concentration of 0.4 fM DNA. This study provides a rapid and low-cost approach for DNA detection with high sensitivity, showing great promise for clinical application and biomedical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A rapid-screening approach to detect and quantify microplastics based on fluorescent tagging with Nile Red

    Science.gov (United States)

    Maes, Thomas; Jessop, Rebecca; Wellner, Nikolaus; Haupt, Karsten; Mayes, Andrew G.

    2017-03-01

    A new approach is presented for analysis of microplastics in environmental samples, based on selective fluorescent staining using Nile Red (NR), followed by density-based extraction and filtration. The dye adsorbs onto plastic surfaces and renders them fluorescent when irradiated with blue light. Fluorescence emission is detected using simple photography through an orange filter. Image-analysis allows fluorescent particles to be identified and counted. Magnified images can be recorded and tiled to cover the whole filter area, allowing particles down to a few micrometres to be detected. The solvatochromic nature of Nile Red also offers the possibility of plastic categorisation based on surface polarity characteristics of identified particles. This article details the development of this staining method and its initial cross-validation by comparison with infrared (IR) microscopy. Microplastics of different sizes could be detected and counted in marine sediment samples. The fluorescence staining identified the same particles as those found by scanning a filter area with IR-microscopy.

  3. Improving your four-dimensional image: traveling through a decade of light-sheet-based fluorescence microscopy research.

    Science.gov (United States)

    Strobl, Frederic; Schmitz, Alexander; Stelzer, Ernst H K

    2017-06-01

    Light-sheet-based fluorescence microscopy features optical sectioning in the excitation process. This reduces phototoxicity and photobleaching by up to four orders of magnitude compared with that caused by confocal fluorescence microscopy, simplifies segmentation and quantification for three-dimensional cell biology, and supports the transition from on-demand to systematic data acquisition in developmental biology applications.

  4. Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions

    Directory of Open Access Journals (Sweden)

    Maryam Mobed-Miremadi

    2014-12-01

    Full Text Available Hollow alginate microfibers (od = 1.3 mm, id = 0.9 mm, th = 400 µm, L = 3.5 cm comprised of 2% (w/v medium molecular weight alginate cross-linked with 0.9 M CaCl2 were fabricated to model outward diffusion capture by 2D fluorescent microscopy. A two-fold comparison of diffusivity determination based on real-time diffusion of Fluorescein isothiocyanate molecular weight (FITC MW markers was conducted using a proposed Fickian-based approach in conjunction with a previously established numerical model developed based on spectrophotometric data. Computed empirical/numerical (Dempiricial/Dnumerical diffusivities characterized by small standard deviations for the 4-, 70- and 500-kDa markers expressed in m2/s are (1.06 × 10−9 ± 1.96 × 10−10/(2.03 × 10−11, (5.89 × 10−11 ± 2.83 × 10−12/(4.6 × 10−12 and (4.89 × 10−12 ± 3.94 × 10−13/(1.27 × 10−12, respectively, with the discrimination between the computation techniques narrowing down as a function of MW. The use of the numerical approach is recommended for fluorescence-based measurements as the standard computational method for effective diffusivity determination until capture rates (minimum 12 fps for the 4-kDa marker and the use of linear instead of polynomial interpolating functions to model temporal intensity gradients have been proven to minimize the extent of systematic errors associated with the proposed empirical method.

  5. A high-throughput direct fluorescence resonance energy transfer-based assay for analyzing apoptotic proteases using flow cytometry and fluorescence lifetime measurements.

    Science.gov (United States)

    Suzuki, Miho; Sakata, Ichiro; Sakai, Takafumi; Tomioka, Hiroaki; Nishigaki, Koichi; Tramier, Marc; Coppey-Moisan, Maïté

    2015-12-15

    Cytometry is a versatile and powerful method applicable to different fields, particularly pharmacology and biomedical studies. Based on the data obtained, cytometric studies are classified into high-throughput (HTP) or high-content screening (HCS) groups. However, assays combining the advantages of both are required to facilitate research. In this study, we developed a high-throughput system to profile cellular populations in terms of time- or dose-dependent responses to apoptotic stimulations because apoptotic inducers are potent anticancer drugs. We previously established assay systems involving protease to monitor live cells for apoptosis using tunable fluorescence resonance energy transfer (FRET)-based bioprobes. These assays can be used for microscopic analyses or fluorescence-activated cell sorting. In this study, we developed FRET-based bioprobes to detect the activity of the apoptotic markers caspase-3 and caspase-9 via changes in bioprobe fluorescence lifetimes using a flow cytometer for direct estimation of FRET efficiencies. Different patterns of changes in the fluorescence lifetimes of these markers during apoptosis were observed, indicating a relationship between discrete steps in the apoptosis process. The findings demonstrate the feasibility of evaluating collective cellular dynamics during apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Dual Colorimetric and Fluorescent Authentication Based on Semiconducting Polymer Dots for Anticounterfeiting Applications.

    Science.gov (United States)

    Tsai, Wei-Kai; Lai, Yung-Sheng; Tseng, Po-Jung; Liao, Chia-Hsien; Chan, Yang-Hsiang

    2017-09-13

    Semiconducting polymer dots (Pdots) have recently emerged as a novel type of ultrabright fluorescent probes that can be widely used in analytical sensing and material science. Here, we developed a dual visual reagent based on Pdots for anticounterfeiting applications. We first designed and synthesized two types of photoswitchable Pdots by incorporating photochromic dyes with multicolor semiconducting polymers to modulate their emission intensities and wavelengths. The resulting full-color Pdot assays showed that the colorimetric and fluorescent dual-readout abilities enabled the Pdots to serve as an anticounterfeiting reagent with low background interference. We also doped these Pdots into flexible substrates and prepared these Pdots as inks for pen handwriting as well as inkjet printing. We further applied this reagent in printing paper and checks for high-security anticounterfeiting purposes. We believe that this dual-readout method based on Pdots will create a new avenue for developing new generations of anticounterfeiting technologies.

  7. A facile fluorescent "turn-off" method for sensing paraquat based on pyranine-paraquat interaction

    Science.gov (United States)

    Zhao, Zuzhi; Zhang, Fengwei; Zhang, Zipin

    2018-06-01

    Development of a technically simple yet effective method for paraquat (PQ) detection is of great importance due to its high clinical and environmental relevance. In this study, we developed a pyranine-based fluorescent "turn-off" method for PQ sensing based on pyranine-PQ interaction. We investigated the dependence of analytical performance of this method on the experimental conditions, such as the ion strength, medium pH, and so on. Under the optimized conditions, the method is sensitive and selective, and could be used for PQ detection in real-world sample. This study essentially provides a readily accessible fluorescent system for PQ sensing which is cheap, robust, and technically simple, and it is envisaged to find more interesting clinical and environmental applications.

  8. A comparative study of oxygen transmission rates through polymer films based on fluorescence quenching

    DEFF Research Database (Denmark)

    Siró, Istvan; Plackett, David; Sommer-Larsen, Peter

    2010-01-01

    Information on oxygen permeability through polymer films is essential for some applications, especially in food packaging where the control of oxygen levels can be critical in avoiding food spoilage. A permeability testing device using fluorescence-based optical oxygen sensing was developed...... as a potential new instrument for measuring the oxygen permeability of packaging films. The fluorescence-based permeability tester was validated against two existing commercial oxygen permeability measuring devices, the Mocon Ox-Tran 2/20 and PBI-Dansensor OPT-5000. Oxygen transmission rates (OTR) of polylactide...... (PLA) and nanoclay-reinforced PLA films, as well as polyethylene/poly(ethylene terephthalate) (PE/PET) and polypropylene/poly(ethylene terephthalate) (PP/PET) laminated films were determined at 23°C and 50% relative humidity using each of these instruments. No significant differences were observed...

  9. Characterization of LiF-based soft X-ray imaging detectors by confocal fluorescence microscopy

    International Nuclear Information System (INIS)

    Bonfigli, F; Gaudio, P; Lupelli, I; Nichelatti, E; Richetta, M; Vincenti, M A; Montereali, R M

    2010-01-01

    X-ray microscopy represents a powerful tool to obtain images of samples with very high spatial resolution. The main limitation of this technique is represented by the poor spatial resolution of standard imaging detectors. We proposed an innovative high-performance X-ray imaging detector based on the visible photoluminescence of colour centres in lithium fluoride. In this work, a confocal microscope in fluorescence mode was used to characterize LiF-based imaging detectors measuring CC integrated visible fluorescence signals of LiF crystals and films (grown on several kinds of substrates) irradiated by soft X-rays produced by a laser plasma source in different exposure conditions. The results are compared with the CC photoluminescence spectra measured on the same samples and discussed.

  10. A generic, geometric cocalibration method for a combined system of fluorescence molecular tomography and microcomputed tomography with arbitrarily shaped objects

    International Nuclear Information System (INIS)

    Fu Jianwei; Yang Xiaoquan; Wang Kan; Luo Qingming; Gong Hui

    2011-01-01

    Purpose: A combined system of fluorescence molecular tomography and microcomputed tomography (FMT and mCT) can provide molecular and anatomical information of small animals in a single study with intrinsically coregistered images. The anatomical information provided by the mCT subsystem is commonly used as a reference to locate the fluorophore distribution or as a priori structural information to improve the performance of FMT. Therefore, the transformation between the coordinate systems of the subsystem needs to be determined in advanced. Methods: A cocalibration method for the combined system of FMT and mCT is proposed. First, linear models are adopted to describe the galvano mirrors and the charge-coupled device (CCD) camera in the FMT subsystem. Second, the position and orientation of the galvano mirrors are determined with the input voltages of the galvano mirrors and the markers, whose positions are predetermined. The position, orientation and normalized pixel size of the CCD camera are obtained by analysing the projections of a point-like marker at different positions. Finally, the orientation and position of sources and the corresponding relationship between the detectors and their projections on the image plane are predicted. Because the positions of the markers are acquired with mCT, the registration of the FMT and mCT could be realized by direct image fusion. Results: The accuracy and consistency of this method in the presence of noise is evaluated by computer simulation. Next, a practical implementation for an experimental FMT and mCT system is carried out and validated. The maximum prediction error of the source positions on the surface of a cylindrical phantom is within 0.375 mm and that of the projections of a point-like marker is within 0.629 pixel. Finally, imaging experiments of the fluorophore distribution in a cylindrical phantom and a phantom with a complex shape demonstrate the feasibility of the proposed method. Conclusions: This method is

  11. Energetics and dynamics of the non-natural fluorescent 4AP:DAP base pair

    KAUST Repository

    Chawla, Mohit; Autiero, Ida; Oliva, Romina; Cavallo, Luigi

    2018-01-01

    the experimental studies and rationalize the impact of the above non-natural bases on the structure, stability and dynamics of nucleic acid structures, we performed quantum mechanics (QM) calculations along with classical molecular dynamics (MD) simulations. QM

  12. [Department of the molecular bases of semiotics].

    Science.gov (United States)

    Ternovyĭ, K S

    1995-01-01

    Department of molecular basis of semiotics was organized in 1986. The main task of the department was to work out new approaches in estimation of the state of immune and blood system at the tissue, cell and molecular levels, using biochemical, biophysical and molecular biology techniques. There are several main directions of scientific investigations at the department. Most informational methods were collected in "immunological portrait" for differential diagnostic and complex investigation of the immune system of autoimmune patients. This group of techniques was used to study changes in the immune system of Kievites after the Chernobyl disaster. A decrease of complement and thymic serum activity was detected. Antibodies against nuclear components appeared in 20% of donors. And a higher of circulating immune complex of low molecular weight was observed. Low level of thymic serum activity in blood of autoimmune patients with rheumatoid arthritis, lupus erythematosus, diabetes, herpes and other depends on the appearance of zinc-independent timuline inhibitor less then 2000 D. Another kind of thymic hormone inhibitors was detected in thymectomized adult mice. Its effect disappears when zinc added in blood rather due to competition for lymphocyte surface receptors timuline and its inactive analogue than other mechanism. Therapeutic effect of UV irradiation of patients' blood was shown to be closely connected with the changes in thymic serum activity in respect to stabilization of thymic hormone/inhibitor ratio. The immunochemical techniques were used to detect and investigate tumor-associated chromatin antigens in human and animal tumor cells. Antigens not found in normal tissues were detected when using rabbit antibodies against chromatin of rat hepatocarcinoma and human colon and carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Imaging molecular interactions in cells by dynamic and static fluorescence anisotropy (rFLIM and emFRET)

    NARCIS (Netherlands)

    Lidke, D.S.; Nagy, P.; Barisas, B.G.; Heintzmann, R.; Post, Janine Nicole; Lidke, K.A.; Clayton, A.H.A.; Arndt-jovin, D.J.; Jovin, T.M.

    2003-01-01

    We report the implementation and exploitation of fluorescence polarization measurements, in the form of anisotropy fluorescence lifetime imaging microscopy (rFLIM) and energy migration Förster resonance energy transfer (emFRET) modalities, for wide-field, confocal laser-scanning microscopy and flow

  14. Fabrication and imaging study of ultrasound/fluorescence bi-modal contrast agent based on polymeric microbubbles

    International Nuclear Information System (INIS)

    Xing Zhanwen; Ke Hengte; Wang Jinrui; Zhao Bo; Qu Enze; Yue Xiuli; Dai Zhifei

    2013-01-01

    based on polymeric microbubbles has been successfully fabricated for the use of ultrasound and fluorescence imaging. It retains the good characteristics of both echogenicity and fluorescence, which complement each other in case of limitations imposed by uni-modal, single agents. (authors)

  15. Integrated three-dimensional optical MEMS for chip-based fluorescence detection

    Science.gov (United States)

    Hung, Kuo-Yung; Tseng, Fan-Gang; Khoo, Hwa-Seng

    2009-04-01

    This paper presents a novel fluorescence sensing chip for parallel protein microarray detection in the context of a 3-in-1 protein chip system. This portable microchip consists of a monolithic integration of CMOS-based avalanche photo diodes (APDs) combined with a polymer micro-lens, a set of three-dimensional (3D) inclined mirrors for separating adjacent light signals and a low-noise transformer-free dc-dc boost mini-circuit to power the APDs (ripple below 1.28 mV, 0-5 V input, 142 V and 12 mA output). We fabricated our APDs using the planar CMOS process so as to facilitate the post-CMOS integration of optical MEMS components such as the lenses. The APD arrays were arranged in unique circular patterns appropriate for detecting the specific fluorescently labelled protein spots in our study. The array-type APDs were designed so as to compensate for any alignment error as detected by a positional error signal algorithm. The condenser lens was used as a structure for light collection to enhance the fluorescent signals by about 25%. This element also helped to reduce the light loss due to surface absorption. We fabricated an inclined mirror to separate two adjacent fluorescent signals from different specimens. Excitation using evanescent waves helped reduce the interference of the excitation light source. This approach also reduced the number of required optical lenses and minimized the complexity of the structural design. We achieved detection floors for anti-rabbit IgG and Cy5 fluorescent dye as low as 0.5 ng/µl (~3.268 nM). We argue that the intrinsic nature of point-to-point and batch-detection methods as showcased in our chip offers advantages over the serial-scanning approach used in traditional scanner systems. In addition, our system is low cost and lightweight.

  16. Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

    Science.gov (United States)

    Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

    2016-04-01

    Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be

  17. Smartphone-Based Fluorescent Diagnostic System for Highly Pathogenic H5N1 Viruses

    OpenAIRE

    Yeo, Seon-Ju; Choi, Kyunghan; Cuc, Bui Thi; Hong, Nguyen Ngoc; Bao, Duong Tuan; Ngoc, Nguyen Minh; Le, Mai Quynh; Hang, Nguyen Le Khanh; Thach, Nguyen Co; Mallik, Shyam Kumar; Kim, Hak Sung; Chong, Chom-Kyu; Choi, Hak Soo; Sung, Haan Woo; Yu, Kyoungsik

    2016-01-01

    Field diagnostic tools for avian influenza (AI) are indispensable for the prevention and controlled management of highly pathogenic AI-related diseases. More accurate, faster and networked on-site monitoring is demanded to detect such AI viruses with high sensitivity as well as to maintain up-to-date information about their geographical transmission. In this work, we assessed the clinical and field-level performance of a smartphone-based fluorescent diagnostic device with an efficient reflect...

  18. A resorcinarene-based “turn-off” fluorescence sensor for 4-nitrotoluene: Insights from fluorescence and {sup 1}H NMR titration with computational approach

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Urvi; Modi, Krunal; Dey, Shuvankar; Prajapati, Usha [Department of Chemistry, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India); Patel, Chirag [Department of Bioinformatics, Applied Botany Centre (ABC), University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India); Jain, V.K., E-mail: drvkjain@hotmail.com [Department of Chemistry, University School of Sciences, Gujarat University, Ahmedabad 380009, Gujarat (India)

    2017-04-15

    A new Tetra-Methoxy Resorcinarene-N-(2-ethyl) Phthalimide (TMRN2Ph) has been synthesized for the selective and sensitive recognition of 4-nitrotoluene (4-NT) among various nitroaromatic compounds (NACs) by using a spectrofluorimetric method. Strong quenching in the fluorescence intensity of TMRN2Ph was displayed upon the addition of 4-NT in the linear concentration range of 50 µM to 1 mM. The complexation between TMRN2Ph and 4-NT is supported by ESI-MS and {sup 1}H NMR analysis. The complex of TMRN2Ph with 4-NT has been investigated by computational methods such as molecular docking and molecular dynamics to determine the binding interactions and conformational changes. The detection of 4-NT from a water sample has also been performed successfully.

  19. A highly sensitive fluorescence resonance energy transfer aptasensor for staphylococcal enterotoxin B detection based on exonuclease-catalyzed target recycling strategy

    International Nuclear Information System (INIS)

    Wu, Shijia; Duan, Nuo; Ma, Xiaoyuan; Xia, Yu; Wang, Hongxin; Wang, Zhouping

    2013-01-01

    Graphical abstract: -- Highlights: •An ultrasensitive FRET aptasensor was developed for staphylococcal enterotoxin B determination. •SEB was recognized by SEB aptamer with high affinity and specificity. •The Mn 2+ doped NaYF 4 :Yb/Er UCNPs used as donor to quencher dye (BHQ 3 ) in new FRET. •The fluorescence intensity was prominently amplified using an exonuclease-catalyzed target recycling strategy. -- Abstract: An ultrasensitive fluorescence resonance energy transfer (FRET) bioassay was developed to detect staphylococcal enterotoxin B (SEB), a low molecular exotoxin, using an aptamer-affinity method coupled with upconversion nanoparticles (UCNPs)-sensing, and the fluorescence intensity was prominently enhanced using an exonuclease-catalyzed target recycling strategy. To construct this aptasensor, both fluorescence donor probes (complementary DNA 1 –UCNPs) and fluorescence quencher probes (complementary DNA 2 –Black Hole Quencher 3 (BHQ 3 )) were hybridized to an SEB aptamer, and double-strand oligonucleotides were fabricated, which quenched the fluorescence of the UCNPs via FRET. The formation of an aptamer–SEB complex in the presence of the SEB analyte resulted in not only the dissociation of aptamer from the double-strand DNA but also both the disruption of the FRET system and the restoration of the UCNPs fluorescence. In addition, the SEB was liberated from the aptamer–SEB complex using exonuclease I, an exonuclease specific to single-stranded DNA, for analyte recycling by selectively digesting a particular DNA (SEB aptamer). Based on this exonuclease-catalyzed target recycling strategy, an amplified fluorescence intensity could be produced using different SEB concentrations. Using optimized experimental conditions produced an ultrasensitive aptasensor for the detection of SEB, with a wide linear range of 0.001–1 ng mL −1 and a lower detection limit (LOD) of 0.3 pg mL −1 SEB (at 3σ). The fabricated aptasensor was used to measure SEB in a

  20. Pancreatic tumor detection using hypericin-based fluorescence spectroscopy and cytology

    Science.gov (United States)

    Lavu, Harish; Geary, Kevin; Fetterman, Harold R.; Saxton, Romaine E.

    2005-04-01

    Hypericin is a novel, highly fluorescent photosensitizer that exhibits selective tumor cell uptake properties and is particularly resistant to photobleaching. In this study, we have characterized hypericin uptake in human pancreatic tumor cells with relation to incubation time, cell number, and drug concentration. Ex vivo hypericin based fluorescence spectroscopy was performed to detect the presence of MIA PaCa-2 pancreatic tumor cells in the peritoneal cavity of BALB/c nude mice, as well as to quantify gross tumor burden. Hypericin based cytology of peritoneal lavage samples, using both one and two photon laser confocal microscopy, demonstrated more than a two-fold increase in fluorescence emission of pancreatic tumor cells as compared to control samples. In vitro treatment of pancreatic cancer cells with hypericin based photodynamic therapy showed tumor cell cytotoxicity in a drug dose, incident laser power, and time dependent manner. For these experiments, a continuous wavelength solid-state laser source (532 nm) was operated at power levels in the range of 100-400 mW. Potential applications of hypericin in tumor diagnosis, staging, and therapy will be presented.

  1. Detection of vegetation LUE based on chlorophyll fluorescence separation algorithm from Fraunhofer line

    Science.gov (United States)

    Liu, Liangyun; Zhang, Bing

    2009-09-01

    Photosynthetic efficiency is very important, and not yet generally assessable by remote sensing. Much research has proved the possibility of the separation of solar-induced chlorophyll fluorescence (ChlF) from the reflected hyperspectral data. As the 'probe' of plant photosynthesis, it is possible to detect photosynthetic light use efficiency (LUE) by the separated solar-induced ChlF. A diurnal experiment was carried out on winter wheat on Apr. 18, 2008, and the canopy radiance spectra and leaf LUE data were measured synchronously. The solar-induced chlorophyll fluorescence signals at 760nm and 688nm were separated from the reflected radiance spectral based on Fraunhofer lines in two oxygen absorption bands. The result showed that LUE was negatively correlated to the separated chlorophyll signals. The statistical models for LUE based on the solar-induced chlorophyll fluorescence values at 688 nm and 760 nm bands had correlation coefficients (R2) of 0.64 and 0.78, respectively. In addition, photochemical reflectance index (PRI) was also linked to LUE, and a statistical model for LUE based on PRI has a correlation coefficient (R2) of 0.66. The presented method provides a novel solution for monitoring LUE from remote sensing data.

  2. Fluorescently labelled multiplex lateral flow immunoassay based on cadmium-free quantum dots.

    Science.gov (United States)

    Beloglazova, Natalia V; Sobolev, Aleksander M; Tessier, Mickael D; Hens, Zeger; Goryacheva, Irina Yu; De Saeger, Sarah

    2017-03-01

    A sensitive tool for simultaneous qualitative detection of two mycotoxins based on use of non-cadmium quantum dots (QDs) is presented for the first time. QDs have proven themselves as promising fluorescent labels for biolabeling and chemical analysis. With an increasing global tendency to regulate and limit the use of hazardous elements, indium phosphide (InP) QDs are highlighted as environmentally-friendly alternatives to the highly efficient and well-studied, but potentially toxic Cd- and Pb-based QDs. Here, we developed water-soluble InP QDs-based fluorescent nanostructures. They consisted of core/shell InP/ZnS QDs enrobed in a silica shell that allowed the water solubility (QD@SiO 2 ). Then we applied the QD@SiO 2 as novel, silica shell-encapsulated fluorescent labels in immunoassays for rapid multiplexed screening. Two mycotoxins, zearalenone and deoxynivalenol, were simultaneously detected in maize and wheat, since the two QD@SiO 2 labelled conjugates emit at two different, individually detectable wavelengths. The cutoff values for the simultaneous determination were 50 and 500μgkg -1 for zearalenone and deoxynivalenol, respectively, in both maize and wheat. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to confirm the result. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. A Pyridazine-Based Fluorescent Probe Targeting Aβ Plaques in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Yong Dae Park

    2018-01-01

    Full Text Available Accumulation of β-amyloid (Aβ plaques comprising Aβ40 and Aβ42 in the brain is the most significant factor in the pathogenesis of Alzheimer’s disease (AD. Thus, the detection of Aβ plaques has increasingly attracted interest in the context of AD diagnosis. In the present study, a fluorescent pyridazine-based dye that can detect and image Aβ plaques was designed and synthesized, and its optical properties in the presence of Aβ aggregates were evaluated. An approximately 34-fold increase in emission intensity was exhibited by the fluorescent probe after binding with Aβ aggregates, for which it showed high affinity (KD = 0.35 µM. Moreover, the reasonable hydrophobic properties of the probe (log P = 2.94 allow it to penetrate the blood brain barrier (BBB. In addition, the pyridazine-based probe was used in the histological costaining of transgenic mouse (APP/PS1 brain sections to validate the selective binding of the probe to Aβ plaques. The results suggest that the pyridazine-based compound has the potential to serve as a fluorescent probe for the diagnosis of AD.

  4. Fluorescence intensity and lifetime-based cyanide sensitive probes for physiological safeguard

    International Nuclear Information System (INIS)

    Badugu, Ramachandram; Lakowicz, Joseph R.; Geddes, Chris D.

    2004-01-01

    We characterize six new fluorescent probes that show both intensity and lifetime changes in the presence of free uncomplexed aqueous cyanide, allowing for fluorescence based cyanide sensing up to physiological safeguard levels, i.e. 2 to the anionic R-B - (CN) 3 form, a new cyanide binding mechanism which we have recently reported. The presence of an electron deficient quaternary heterocyclic nitrogen nucleus, and the electron rich cyanide bound form, provides for the intensity changes observed. We have determined the disassociation constants of the probes to be in the range ∼15-84 μM 3 . In addition we have synthesized control compounds which do not contain the boronic acid moiety, allowing for a rationale of the cyanide responses between the probe isomers to be made. The lifetime of the cyanide bound probes are significantly shorter than the free R-B(OH) 2 probe forms, providing for the opportunity of lifetime based cyanide sensing up to physiologically lethal levels. Finally, while fluorescent probes containing the boronic acid moiety have earned a well-deserved reputation for monosaccharide sensing, we show that strong bases such as CN - and OH - preferentially bind as compared to glucose, enabling the potential use of these probes for cyanide safeguard and determination in physiological fluids, especially given that physiologies do not experience any notable changes in pH

  5. Smart Drug Delivery System-Inspired Enzyme-Linked Immunosorbent Assay Based on Fluorescence Resonance Energy Transfer and Allochroic Effect Induced Dual-Modal Colorimetric and Fluorescent Detection.

    Science.gov (United States)

    Miao, Luyang; Zhu, Chengzhou; Jiao, Lei; Li, He; Du, Dan; Lin, Yuehe; Wei, Qin

    2018-02-06

    Numerous analytical techniques have been undertaken for the detection of protein biomarkers because of their extensive and significant applications in clinical diagnosis, whereas there are few strategies to develop dual-readout immunosensors to achieve more accurate results. To the best of our knowledge, inspired by smart drug delivery system (DDS), a novel pH-responsive modified enzyme-linked immunosorbent assay (ELISA) was innovatively developed for the first time, realizing dual-modal colorimetric and fluorescent detection of cardiac troponin I (cTnI). Curcumin (CUR) was elaborately selected as a reporter molecule, which played the same role of drugs in DDS based on the following considerations: (1) CUR can be used as a kind of pH indicator by the inherited allochroic effect induced by basic pH value; (2) the fluorescence of CUR can be quenched by certain nanocarriers as the acceptor because of the occurrence of fluorescence resonance energy transfer (FRET), while recovered by the stimuli of basic pH value, which can produce "signal-on" fluorescence detection. Three-dimensional MoS 2 nanoflowers (3D-MoS 2 NFs) were employed in immobilizing CUR to constitute a nanoprobe for the determination of cTnI by virtue of good biocompatibility, high absorption capacity, and fluorescence quench efficiency toward CUR. The proposed DDS-inspired ELISA offered dual-modal colorimetric and fluorescent detection of cTnI, thereby meeting the reliable and precise analysis requirements. We believe that the developed dual-readout ELISA will create a new avenue and bring innovative inspirations for biological detections.

  6. Chemosensors and biosensors based on polyelectrolyte microcapsules containing fluorescent dyes and enzymes.

    Science.gov (United States)

    Kazakova, Lyubov I; Shabarchina, Lyudmila I; Anastasova, Salzitsa; Pavlov, Anton M; Vadgama, Pankaj; Skirtach, Andre G; Sukhorukov, Gleb B

    2013-02-01

    The concept of enzyme-assisted substrate sensing based on use of fluorescent markers to detect the products of enzymatic reaction has been investigated by fabrication of micron-scale polyelectrolyte capsules containing enzymes and dyes in one entity. Microcapsules approximately 5 μm in size entrap glucose oxidase or lactate oxidase, with peroxidase, together with the corresponding markers Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride (Ru(dpp)) complex and dihydrorhodamine 123 (DHR123), which are sensitive to oxygen and hydrogen peroxide, respectively. These capsules are produced by co-precipitation of calcium carbonate particles with the enzyme followed by layer-by-layer assembly of polyelectrolytes over the surface of the particles and incorporation of the dye in the capsule interior or in the multilayer shell. After dissolution of the calcium carbonate the enzymes and dyes remain in the multilayer capsules. In this study we produced enzyme-containing microcapsules sensitive to glucose and lactate. Calibration curves based on fluorescence intensity of Ru(dpp) and DHR123 were linearly dependent on substrate concentration, enabling reliable sensing in the millimolar range. The main advantages of using these capsules with optical recording is the possibility of building single capsule-based sensors. The response from individual capsules was observed by confocal microscopy as increasing fluorescence intensity of the capsule on addition of lactate at millimolar concentrations. Because internalization of the micron-sized multi-component capsules was feasible, they could be further optimized for in-situ intracellular sensing and metabolite monitoring on the basis of fluorescence reporting.

  7. Synthesis and validation of novel cholesterol-based fluorescent lipids designed to observe the cellular trafficking of cationic liposomes.

    Science.gov (United States)

    Kim, Bieong-Kil; Seu, Young-Bae; Choi, Jong-Soo; Park, Jong-Won; Doh, Kyung-Oh

    2015-09-15

    Cholesterol-based fluorescent lipids with ether linker were synthesized using NBD (Chol-E-NBD) or Rhodamine B (Chol-E-Rh), and the usefulnesses as fluorescent probes for tracing cholesterol-based liposomes were validated. The fluorescent intensities of liposomes containing these modified lipids were measured and observed under a microscope. Neither compound interfered with the expression of GFP plasmid, and live cell images were obtained without interferences. Changes in the fluorescent intensity of liposomes containing Chol-E-NBD were followed by flow cytometry for up to 24h. These fluorescent lipids could be useful probes for trafficking of cationic liposome-mediated gene delivery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Quantum Dot-Fullerene Based Molecular Beacon Nanosensors for Rapid, Highly Sensitive Nucleic Acid Detection.

    Science.gov (United States)

    Liu, Ye; Kannegulla, Akash; Wu, Bo; Cheng, Li-Jing

    2018-05-15

    Spherical fullerene (C 60 ) can quench the fluorescence of a quantum dot (QD) through energy transfer and charge transfer processes, with the quenching efficiency regulated by the number of proximate C 60 on each QD. With the quenching property and its small size compared with other nanoparticle-based quenchers, it is advantageous to group a QD reporter and multiple C 60 -labeled oligonucleotide probes to construct a molecular beacon (MB) probe for sensitive, robust nucleic acid detection. We demonstrated a rapid, high-sensitivity DNA detection method using the nanosensors composed of QD-C 60 based MBs carried by magnetic nanoparticles (MNPs). The assay was accelerated by first dispersing the nanosensors in analytes for highly efficient DNA capture resulting from short-distance 3-dimensional diffusion of targets to the sensor surface and then concentrating the nanosensors to a substrate by magnetic force to amplify the fluorescence signal for target quantification. The enhanced mass transport enabled a rapid detection (< 10 min) with a small sample volume (1-10 µl). The high signal-to-noise ratio produced by the QD-C 60 pairs and magnetic concentration yielded a detection limit of 100 fM (~106 target DNA copies for a 10 µl analyte). The rapid, sensitive, label-free detection method will benefit the applications in point-of-care molecular diagnostic technologies.

  9. Molecular bases of methamphetamine-induced neurodegeneration.

    Science.gov (United States)

    Cadet, Jean Lud; Krasnova, Irina N

    2009-01-01

    Methamphetamine (METH) is a highly addictive psychostimulant drug, whose abuse has reached epidemic proportions worldwide. The addiction to METH is a major public concern because its chronic abuse is associated with serious health complications including deficits in attention, memory, and executive functions in humans. These neuropsychiatric complications might, in part, be related to drug-induced neurotoxic effects, which include damage to dopaminergic and serotonergic terminals, neuronal apoptosis, as well as activated astroglial and microglial cells in the brain. Thus, the purpose of the present paper is to review cellular and molecular mechanisms that might be responsible for METH neurotoxicity. These include oxidative stress, activation of transcription factors, DNA damage, excitotoxicity, blood-brain barrier breakdown, microglial activation, and various apoptotic pathways. Several approaches that allow protection against METH-induced neurotoxic effects are also discussed. Better understanding of the cellular and molecular mechanisms involved in METH toxicity should help to generate modern therapeutic approaches to prevent or attenuate the long-term consequences of psychostimulant use disorders in humans.

  10. Simple, fast, and low-cost camera-based water content measurement with colorimetric fluorescent indicator

    Science.gov (United States)

    Song, Seok-Jeong; Kim, Tae-Il; Kim, Youngmi; Nam, Hyoungsik

    2018-05-01

    Recently, a simple, sensitive, and low-cost fluorescent indicator has been proposed to determine water contents in organic solvents, drugs, and foodstuffs. The change of water content leads to the change of the indicator's fluorescence color under the ultra-violet (UV) light. Whereas the water content values could be estimated from the spectrum obtained by a bulky and expensive spectrometer in the previous research, this paper demonstrates a simple and low-cost camera-based water content measurement scheme with the same fluorescent water indicator. Water content is calculated over the range of 0-30% by quadratic polynomial regression models with color information extracted from the captured images of samples. Especially, several color spaces such as RGB, xyY, L∗a∗b∗, u‧v‧, HSV, and YCBCR have been investigated to establish the optimal color information features over both linear and nonlinear RGB data given by a camera before and after gamma correction. In the end, a 2nd order polynomial regression model along with HSV in a linear domain achieves the minimum mean square error of 1.06% for a 3-fold cross validation method. Additionally, the resultant water content estimation model is implemented and evaluated in an off-the-shelf Android-based smartphone.

  11. Determining the ice-binding planes of antifreeze proteins by fluorescence-based ice plane affinity.

    Science.gov (United States)

    Basu, Koli; Garnham, Christopher P; Nishimiya, Yoshiyuki; Tsuda, Sakae; Braslavsky, Ido; Davies, Peter

    2014-01-15

    Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice through their ice-binding surfaces. Fluorescence-based ice plane affinity (FIPA) analysis is a modified technique used to determine the ice planes to which the AFPs bind. FIPA is based on the original ice-etching method for determining AFP-bound ice-planes. It produces clearer images in a shortened experimental time. In FIPA analysis, AFPs are fluorescently labeled with a chimeric tag or a covalent dye then slowly incorporated into a macroscopic single ice crystal, which has been preformed into a hemisphere and oriented to determine the a- and c-axes. The AFP-bound ice hemisphere is imaged under UV light to visualize AFP-bound planes using filters to block out nonspecific light. Fluorescent labeling of the AFPs allows real-time monitoring of AFP adsorption into ice. The labels have been found not to influence the planes to which AFPs bind. FIPA analysis also introduces the option to bind more than one differently tagged AFP on the same single ice crystal to help differentiate their binding planes. These applications of FIPA are helping to advance our understanding of how AFPs bind to ice to halt its growth and why many AFP-producing organisms express multiple AFP isoforms.

  12. Turn-On Fluorescent Chemosensor for Hg2+ Based on Multivalent Rhodamine Ligands

    Science.gov (United States)

    Wang, Xuemei; Iqbal, Mudassir; Huskens, Jurriaan; Verboom, Willem

    2012-01-01

    Rhodamine-based fluorescent chemosensors 1 and 2 exhibit selective fluorescence enhancement to Fe3+ and Hg2+ over other metal ions at 580 nm in CH3CN/H2O (3/1, v/v) solution. Bis(rhodamine) chemosensor 1, under optimized conditions (CH3CN/HEPES buffer (0.02 M, pH = 7.0) (95/5, v/v)), shows a high selectivity and sensitivity to Hg2+, with a linear working range of 0–50 μM, a wide pH span of 4–10, and a detection limit of 0.4 μM Hg2+. PMID:23222686

  13. A rhodamine B-based fluorescent sensor toward highly selective mercury (II) ions detection.

    Science.gov (United States)

    Jiao, Yang; Zhang, Lei; Zhou, Peng

    2016-04-01

    This work presented the design, syntheses and photophysical properties of a rhodamine B-based fluorescence probe, which exhibited a sensitive and selective recognition towards mercury (II). The chemosensor RA (Rhodamine- amide- derivative) contained a 5-aminoisophthalic acid diethyl ester and a rhodamine group, and the property of spirolactone of this chemosensor RA was detected by X-ray crystal structure analyses. Chemosensor RA afforded turn-on fluorescence enhancement and displayed high brightness for Hg(2+), which leaded to the opening of the spirolactone ring and consequently caused the appearance of strong absorption at visible range, moreover, the obvious and characteristic color changed from colorless to pink was observed. We envisioned that the chemosensor RA exhibited a considerable specificity with two mercury (II) ions which was attributed to the open of spirolactone over other interference metal ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. [Identification of spill oil species based on low concentration synchronous fluorescence spectra and RBF neural network].

    Science.gov (United States)

    Liu, Qian-qian; Wang, Chun-yan; Shi, Xiao-feng; Li, Wen-dong; Luan, Xiao-ning; Hou, Shi-lin; Zhang, Jin-liang; Zheng, Rong-er

    2012-04-01

    In this paper, a new method was developed to differentiate the spill oil samples. The synchronous fluorescence spectra in the lower nonlinear concentration range of 10(-2) - 10(-1) g x L(-1) were collected to get training data base. Radial basis function artificial neural network (RBF-ANN) was used to identify the samples sets, along with principal component analysis (PCA) as the feature extraction method. The recognition rate of the closely-related oil source samples is 92%. All the results demonstrated that the proposed method could identify the crude oil samples effectively by just one synchronous spectrum of the spill oil sample. The method was supposed to be very suitable to the real-time spill oil identification, and can also be easily applied to the oil logging and the analysis of other multi-PAHs or multi-fluorescent mixtures.

  15. Fluorescent deep-blue and hybrid white emitting devices based on a naphthalene-benzofuran compound

    KAUST Repository

    Yang, Xiaohui

    2013-08-01

    We report the synthesis, photophysics and electrochemical properties of naphthalene-benzofuran compound 1 and its application in organic light emitting devices. Fluorescent deep-blue emitting devices employing 1 as the emitting dopant embedded in 4-4′-bis(9-carbazolyl)-2,2′-biphenyl (CBP) host show the peak external quantum efficiency of 4.5% and Commission Internationale d\\'Énclairage (CIE) coordinates of (0.15, 0.07). Hybrid white devices using fluorescent blue emitting layer with 1 and a phosphorescent orange emitting layer based on an iridium-complex show the peak external quantum efficiency above 10% and CIE coordinates of (0.31, 0.37). © 2013 Published by Elsevier B.V.

  16. A LabVIEW-Based Virtual Instrument System for Laser-Induced Fluorescence Spectroscopy.