Fluorescent Quantum Dots for Biological Labeling

NASA Technical Reports Server (NTRS)

McDonald, Gene; Nadeau, Jay; Nealson, Kenneth; Storrie-Lomardi, Michael; Bhartia, Rohit

2003-01-01

Fluorescent semiconductor quantum dots that can serve as "on/off" labels for bacteria and other living cells are undergoing development. The "on/off" characterization of these quantum dots refers to the fact that, when properly designed and manufactured, they do not fluoresce until and unless they come into contact with viable cells of biological species that one seeks to detect. In comparison with prior fluorescence-based means of detecting biological species, fluorescent quantum dots show promise for greater speed, less complexity, greater sensitivity, and greater selectivity for species of interest. There are numerous potential applications in medicine, environmental monitoring, and detection of bioterrorism.

A new FRET ratiometric fluorescent chemosensor for Hg2+ and its application in living EC 109 cells

NASA Astrophysics Data System (ADS)

Song, Jianhua; Huai, Manxiu; Wang, Cuicui; Xu, Zhanhui; Zhao, Yufen; Ye, Yong

2015-03-01

On the basis of fluorescent resonance energy transfer, a new fluorophore dyad (L) bearing rhodamine B and naphthalimide was developed as fluorescent ratiometric chemosensor for Hg2+ in aqueous solution. L exhibited high selectivity and excellent sensitivity towards Hg2+ with a broad pH span (1.0-8.0) and the detection limit of L was 2.11 × 10-8 M. Sensor L for the detection of Hg2+ was rapid and the recognizing event could complete in 2.5 min. A significant change in the color could be used for naked-eye detection. The selective fluorescence response of L to Hg2+ is due to the Hg2+-promoted ring opening of spirolactam of rhodamine moiety, leading to a cyclization reaction of thiourea moiety. In addition, fluorescence imaging experiments of Hg2+ in living EC 109 cells demonstrated its value of practical applications in biological systems.

A nano grating tunable MEMS optical filter for high-speed on-chip multispectral fluorescent detection.

PubMed

Truxal, Steven C; Huang, Nien-Tsu; Kurabayashi, Katsuo

2009-01-01

We report a microelectromechanical (MEMS) tunable optical filter and its integration in a fluorescence microscope for high speed on-chip spectral measurements. This integration allows for measurements of any fluorescence sample placed onto the microscope stage. We demonstrate the system capabilities by taking spectral measurements of multicolor fluorescent beads and fluorescently labeled cells passing through a microfluidic cytometer. The system has applications in biological studies where the measurement of multiple fluorescent peaks is restricted by the detection method's speed and sensitivity.

A potential fluorescent probe: Maillard reaction product from glutathione and ascorbic acid for rapid and label-free dual detection of Hg(2+) and biothiols.

PubMed

Dong, Jiang Xue; Song, Xiao Fang; Shi, Yan; Gao, Zhong Feng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2016-07-15

Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20μM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

A laser scanning confocal imaging-surface plasmon resonance system application in real time detection of antibody-antigen interaction

NASA Astrophysics Data System (ADS)

Zhang, H. Y.; Yang, L. Q.; Liu, W. M.

2011-12-01

The laser scanning confocal microscope (LSCM) offers several advantages over conventional optical microscopy, but most LSCM work is qualitative analysis and it is very hard to achieve quantitative detection directly with the changing of the fluorescent intensity. A new real time sensor system for the antibody-antigen interaction detection was built integrating with a LSCM and a wavelength-dependent surface plasmon resonance (SPR) sensor. The system was applied to detect the bonding process of human IgG and fluorescent-labeled affinity purified antibody in real time. The fluorescence images changing is well with that of SPR wavelengths in real time, and the trend of the resonance wavelength shift with the concentrations of antibody is similar to that of the fluorescent intensity changing. The results show that SPR makes up the short of quantificational analysis with LSCM with the high spatial resolution. The sensor system shows the merits of the of the LSCM and SPR synergetic application, which are of great importance for practical application in biosensor and life science for interesting local interaction.

Facile and green synthesis of fluorescent carbon dots with tunable emission for sensors and cells imaging.

PubMed

Diao, Haipeng; Li, Tingting; Zhang, Rong; Kang, Yu; Liu, Wen; Cui, Yanhua; Wei, Shuangyan; Wang, Ning; Li, Lihong; Wang, Haojiang; Niu, Weifen; Sun, Tijian

2018-07-05

Most carbon dots (CDs) conventional fabrication approaches produce single colored fluorescent materials, different methods are required to synthesize distinct carbon dots for specific optical applications. Herein, using one-pot hydrothermal treatment of Syringa obtata Lindl, a facile, low-cost and green assay is achieved in the controllable synthesis of blue and green fluorescent carbon dots. The fluorescent emission of CDs can be well-tuned by adding sodium hydroxide in the precursor solution. Blue fluorescent CDs are applied to Fe 3+ sensing with a low detection limit of 0.11 μM of linear range from 0.5 to 80 μM, and then further extended to analysis river water samples. Green fluorescent CDs can be applied to pH detection, which show a remarkable linear enhancement in the green fluorescence emission region when the pH is increased from 1.98 to 8.95. Eventually, the detection of Fe 3+ and pH are applied for the living cells fluorescent images in MCF-7 cells are achieved successfully, indicating as-synthesized CDs potential toward diverse application as promising candidate. Copyright © 2018 Elsevier B.V. All rights reserved.

Single-molecule detection: applications to ultrasensitive biochemical analysis

NASA Astrophysics Data System (ADS)

Castro, Alonso; Shera, E. Brooks

1995-06-01

Recent developments in laser-based detection of fluorescent molecules have made possible the implementation of very sensitive techniques for biochemical analysis. We present and discuss our experiments on the applications of our recently developed technique of single-molecule detection to the analysis of molecules of biological interest. These newly developed methods are capable of detecting and identifying biomolecules at the single-molecule level of sensitivity. In one case, identification is based on measuring fluorescence brightness from single molecules. In another, molecules are classified by determining their electrophoretic velocities.

Plasmonics Enhanced Smartphone Fluorescence Microscopy.

PubMed

Wei, Qingshan; Acuna, Guillermo; Kim, Seungkyeum; Vietz, Carolin; Tseng, Derek; Chae, Jongjae; Shir, Daniel; Luo, Wei; Tinnefeld, Philip; Ozcan, Aydogan

2017-05-18

Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

Colorimetric and Fluorescent Biosensors Based on Directed Assembly of Nanomaterials with Functional DNA

NASA Astrophysics Data System (ADS)

Liu, Juewen; Lu, Yi

This chapter reviews recent progress in the interface between functional nucleic acids and nanoscale science and technology, and its analytical applications. In particular, the use of metallic nanoparticles as the color reporting groups for the action (binding, catalysis, or both) of aptamers, DNAzymes, and aptazymes is described in detail. Because metallic nanoparticles possess high extinction coefficients and distance-dependent optical properties, they allow highly sensitive detections with minimal consumption of materials. The combination of quantum dots (QDs) with functional nucleic acids as fluorescent sensors is also described. The chapter starts with the design of colorimetric and fluorescent sensors responsive to single analytes, followed by sensors responsive to multiple analytes with controllable cooperativity and multiplex detection using both colorimetric and fluorescent signals in one pot, and ends by transferring solution-based detections into litmus paper type of tests, making them generally applicable and usable for a wide range of on-site and real-time analytical applications such as household tests, environmental monitoring, and clinical diagnostics.

Beyond the margins: real-time detection of cancer using targeted fluorophores

PubMed Central

Zhang, Ray R.; Schroeder, Alexandra B.; Grudzinski, Joseph J.; Rosenthal, Eben L.; Warram, Jason M.; Pinchuk, Anatoly N.; Eliceiri, Kevin W.; Kuo, John S.; Weichert, Jamey P.

2017-01-01

Over the past two decades, synergistic innovations in imaging technology have resulted in a revolution in which a range of biomedical applications are now benefiting from fluorescence imaging. Specifically, advances in fluorophore chemistry and imaging hardware, and the identification of targetable biomarkers have now positioned intraoperative fluorescence as a highly specific real-time detection modality for surgeons in oncology. In particular, the deeper tissue penetration and limited autofluorescence of near-infrared (NIR) fluorescence imaging improves the translational potential of this modality over visible-light fluorescence imaging. Rapid developments in fluorophores with improved characteristics, detection instrumentation, and targeting strategies led to the clinical testing in the early 2010s of the first targeted NIR fluorophores for intraoperative cancer detection. The foundations for the advances that underline this technology continue to be nurtured by the multidisciplinary collaboration of chemists, biologists, engineers, and clinicians. In this Review, we highlight the latest developments in NIR fluorophores, cancer-targeting strategies, and detection instrumentation for intraoperative cancer detection, and consider the unique challenges associated with their effective application in clinical settings. PMID:28094261

BSA Au clusters as a probe for enhanced fluorescence detection using multipulse excitation scheme.

PubMed

Raut, Sangram L; Rich, Ryan; Fudala, Rafal; Kokate, R; Kimball, J D; Borejdo, Julian; Vishwanatha, Jamboor K; Gryczynski, Zygmunt; Gryczynski, Ignacy

2014-01-01

Although BSA Au clusters fluoresce in red region (λmax: 650 nm), they are of limited use due to low fluorescence quantum yield (~6%). Here we report an enhanced fluorescence imaging application of fluorescent bio-nano probe BSA Au clusters using multipulse excitation scheme. Multipulse excitation takes advantage of long fluorescence lifetime (> 1 µs) of BSA Au clusters and enhances its fluorescence intensity 15 times over short lived cellular auto-fluorescence. Moreover we have also shown that by using time gated detection strategy signal (fluorescence of BSA Au clusters) to noise (auto-fluorescence) ratio can be increased by 30 fold. Thereby with multipulse excitation long lifetime probes can be used to develop biochemical assays and perform optical imaging with zero background.

Fluorescence spectroscopy and imaging for noninvasive diagnostics: applications to early cancer detection in the lung

NASA Astrophysics Data System (ADS)

Mycek, Mary-Ann; Urayama, Paul; Zhong, Wei; Sloboda, Roger D.; Dragnev, Konstantin H.; Dmitrovsky, Ethan

2003-10-01

Tissue fluorescence spectroscopy and imaging are being investigated as potential methods for non-invasive detection of pre-neoplastic change in the lung and other organ systems. A substantial contribution to tissue fluorescence is known to arise from endogenous cellular fluorophores. Using steady-state and time-resolved fluorescence spectroscopy and imaging, we characterized the endogenous fluorescence properties of immortalized and carcinogen-transformed human bronchial epithelial cells. Non-invasive sensing of endogenous molecular biomarkers associated with human bronchial pre-neoplasia will be discussed.

Design, properties and application of a facile fluorescence switch for Cu(II).

PubMed

Diao, Haipeng; Niu, Weiping; Liu, Wen; Feng, Liheng; Xie, Jun

2017-01-05

A facile fluorescence switch based on Schiff base 2,2'-[1,3-phenylenbis- (methylidynenitrilo)]bis[benzenethiol] (PMBB) has been developed and used to sensing metal ions. UV-vis absorption and fluorescence emission spectra show that the PMBB receptor has high selectivity and sensitivity for Cu(II) ions. Based on the photoinduced electron transfer (PET) and chelation enhanced fluorescence (CHEF) mechanisms, the receptor exhibits an fluorescence "turn-on" switch signal for Cu(II). The 1:1 binding mode of PMBB and Cu (II) ions can be obtained by the Job-plot and ESI-Mass spectra data. Noticeably, the color changes (from colorless to yellow) of PMBB solutions for Cu(II) sensing can be observed by naked eyes in the sunlight. The detection limit of the receptor for Cu(II) may reach 10(-7)mol/L with a good linear relation in the lower concentrations of Cu(II). To develop the practical application, the Cu(II) ions in swimming pool water samples were detected. Results show that PMBB receptor as a fluorescent probe can use to detect the trace level of Cu(II) in the environmental samples. This work contributes to providing a facile strategy for designing efficient probes and developing their practical application value. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorescence properties of human teeth and dental calculus for clinical applications

NASA Astrophysics Data System (ADS)

Lee, Yong-Keun

2015-04-01

Fluorescent emission of human teeth and dental calculus is important for the esthetic rehabilitation of teeth, diagnosis of dental caries, and detection of dental calculus. The purposes of this review were to summarize the fluorescence and phosphorescence of human teeth by ambient ultraviolet (UV) light, to investigate the clinically relevant fluorescence measurement methods in dentistry, and to review the fluorescence of teeth and dental calculus by specific wavelength light. Dentine was three times more phosphorescent than enamel. When exposed to light sources containing UV components, the fluorescence of human teeth gives them the quality of vitality, and fluorescent emission with a peak of 440 nm is observed. Esthetic restorative materials should have fluorescence properties similar to those of natural teeth. Based on the fluorescence of teeth and restorative materials as determined with a spectrophotometer, a fluorescence parameter was defined. As to the fluorescence spectra by a specific wavelength, varied wavelengths were investigated for clinical applications, and several methods for the diagnosis of dental caries and the detection of dental calculus were developed. Since fluorescent properties of dental hard tissues have been used and would be expanded in diverse fields of clinical practice, these properties should be investigated further, embracing newly developed optical techniques.

Fluorescence properties of human teeth and dental calculus for clinical applications.

PubMed

Lee, Yong-Keun

2015-04-01

Fluorescent emission of human teeth and dental calculus is important for the esthetic rehabilitation of teeth, diagnosis of dental caries, and detection of dental calculus. The purposes of this review were to summarize the fluorescence and phosphorescence of human teeth by ambient ultraviolet (UV) light, to investigate the clinically relevant fluorescence measurement methods in dentistry, and to review the fluorescence of teeth and dental calculus by specific wavelength light. Dentine was three times more phosphorescent than enamel. When exposed to light sources containing UV components, the fluorescence of human teeth gives them the quality of vitality, and fluorescent emission with a peak of 440 nm is observed. Esthetic restorative materials should have fluorescence properties similar to those of natural teeth. Based on the fluorescence of teeth and restorative materials as determined with a spectrophotometer, a fluorescence parameter was defined. As to the fluorescence spectra by a specific wavelength, varied wavelengths were investigated for clinical applications, and several methods for the diagnosis of dental caries and the detection of dental calculus were developed. Since fluorescent properties of dental hard tissues have been used and would be expanded in diverse fields of clinical practice, these properties should be investigated further, embracing newly developed optical techniques.

Detecting RNA/DNA hybridization using double-labeled donor probes with enhanced fluorescence resonance energy transfer signals.

PubMed

Okamura, Yukio; Watanabe, Yuichiro

2006-01-01

Fluorescence resonance energy transfer (FRET) occurs when two fluorophores are in close proximity, and the emission energy of a donor fluorophore is transferred to excite an acceptor fluorophore. Using such fluorescently labeled oligonucleotides as FRET probes, makes possible specific detection of RNA molecules even if similar sequences are present in the environment. A higher ratio of signal to background fluorescence is required for more sensitive probe detection. We found that double-labeled donor probes labeled with BODIPY dye resulted in a remarkable increase in fluorescence intensity compared to single-labeled donor probes used in conventional FRET. Application of this double-labeled donor system can improve a variety of FRET techniques.

Development of ultrasound-assisted fluorescence imaging of indocyanine green.

PubMed

Morikawa, Hiroyasu; Toyota, Shin; Wada, Kenji; Uchida-Kobayashi, Sawako; Kawada, Norifumi; Horinaka, Hiromichi

2017-01-01

Indocyanine green (ICG) accumulation in hepatocellular carcinoma means tumors can be located by fluorescence. However, because of light scattering, it is difficult to detect ICG fluorescence from outside the body. We propose a new fluorescence imaging method that detects changes in the intensity of ICG fluorescence by ultrasound-induced temperature changes. ICG fluorescence intensity decreases as the temperature rises. Therefore, it should theoretically be possible to detect tissue distribution of ICG using ultrasound to heat tissue, moving the point of ultrasound transmission, and monitoring changes in fluorescence intensity. A new probe was adapted for clinical application. It consisted of excitation light from a laser, fluorescence sensing through a light pipe, and heating by ultrasound. We applied the probe to bovine liver to image the accumulation of ICG. ICG emits fluorescence (820 nm) upon light irradiation (783 nm). With a rise in temperature, the fluorescence intensity of ICG decreased by 0.85 %/°C. The distribution of fluorescent ICG was detected using an ultrasonic warming method in a new integrated probe. Modulating fluorescence by changing the temperature using ultrasound can determine where ICG accumulates at a depth, highlighting its potential as a means to locate hepatocellular carcinoma.

A chromogenic and fluorogenic rhodol-based chemosensor for hydrazine detection and its application in live cell bioimaging

NASA Astrophysics Data System (ADS)

Tiensomjitr, Khomsan; Noorat, Rattha; Chomngam, Sinchai; Wechakorn, Kanokorn; Prabpai, Samran; Kanjanasirirat, Phongthon; Pewkliang, Yongyut; Borwornpinyo, Suparerk; Kongsaeree, Palangpon

2018-04-01

A rhodol-based fluorescent probe has been developed as a selective hydrazine chemosensor using levulinate as a recognition site. The rhodol levulinate probe (RL) demonstrated high selectivity and sensitivity toward hydrazine among other molecules. The chromogenic response of RL solution to hydrazine from colorless to pink could be readily observed by the naked eye, while strong fluorescence emission could be monitored upon excitation at 525 nm. The detection process occurred via a ring-opening process of the spirolactone initiated by hydrazinolysis, triggering the fluorescence emission with a 53-fold enhancement. The probe rapidly reacted with hydrazine in aqueous medium with the detection limit of 26 nM (0.83 ppb), lower than the threshold limit value (TLV) of 10 ppb suggested by the U.S. Environmental Protection Agency. Furthermore, RL-impregnated paper strips could detect hydrazine vapor. For biological applicability of RL, its membrane-permeable property led to bioimaging of hydrazine in live HepG2 cells by confocal fluorescence microscopy.

Rapid and ratiometric detection of hypochlorite with real application in tap water: molecules to low cost devices (TLC sticks).

PubMed

Goswami, Shyamaprosad; Manna, Abhishek; Paul, Sima; Quah, Ching Kheng; Fun, Hoong-Kun

2013-12-25

We have designed a chemodosimeter DPNO (weak fluorescence) which can be oxidized to HPNO (strong blue fluorescence) by OCl(-) with high selectivity and sensitivity in a ratiometric approach with a noticeably lower detection limit. The sensor could be useful for the detection of hypochlorites in tap water.

One-step synthesis and applications of fluorescent Cu nanoclusters stabilized by L-cysteine in aqueous solution.

PubMed

Yang, Xiaoming; Feng, Yuanjiao; Zhu, Shanshan; Luo, Yawen; Zhuo, Yan; Dou, Yao

2014-10-17

Herein, an innovative and simple strategy for synthesizing high fluorescent Cu nanoclusters was successfully established while L-cysteine played a role as the stabilizer. Meaningfully, the current Cu nanoclusters together with a quantum yield of 14.3% were prepared in aqueous solution, indicating their extensive applications. Subsequently, the possible fluorescence mechanism was elucidated by fluorescence, UV-vis, HR-TEM, FTIR, XPS, and MS. Additionally, the CuNCs were employed for assaying Hg(2+) on the basis of the interactions between Hg(2+) and L-cysteine; thus facilitating the quenching of their fluorescence. The proposed analytical strategy permitted detections of Hg(2+) in a linear range of 1.0×10(-7) mol L(-1)×10(-3) mol L(-1), with a detection limit of 2.4×10(-8) mol L(-1) at a signal-to-noise ratio of 3. Significantly, this CuNCs described here were further applied for coding and fluorescent staining, suggesting may broaden avenues toward diverse applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Intrinsic Tryptophan Fluorescence in the Detection and Analysis of Proteins: A Focus on Förster Resonance Energy Transfer Techniques

PubMed Central

Ghisaidoobe, Amar B. T.; Chung, Sang J.

2014-01-01

Förster resonance energy transfer (FRET) occurs when the distance between a donor fluorophore and an acceptor is within 10 nm, and its application often necessitates fluorescent labeling of biological targets. However, covalent modification of biomolecules can inadvertently give rise to conformational and/or functional changes. This review describes the application of intrinsic protein fluorescence, predominantly derived from tryptophan (λEX ∼ 280 nm, λEM ∼ 350 nm), in protein-related research and mainly focuses on label-free FRET techniques. In terms of wavelength and intensity, tryptophan fluorescence is strongly influenced by its (or the protein’s) local environment, which, in addition to fluorescence quenching, has been applied to study protein conformational changes. Intrinsic Förster resonance energy transfer (iFRET), a recently developed technique, utilizes the intrinsic fluorescence of tryptophan in conjunction with target-specific fluorescent probes as FRET donors and acceptors, respectively, for real time detection of native proteins. PMID:25490136

The detection of T-Nos, a genetic element present in GMOs, by cross-priming isothermal amplification with real-time fluorescence.

PubMed

Zhang, Fang; Wang, Liu; Fan, Kai; Wu, Jian; Ying, Yibin

2014-05-01

An isothermal cross-priming amplification (CPA) assay for Agrobacterium tumefaciens nopaline synthase terminator (T-Nos) was established and investigated in this work. A set of six specific primers, recognizing eight distinct regions on the T-Nos sequence, was designed. The CPA assay was performed at a constant temperature, 63 °C, and detected by real-time fluorescence. The results indicated that real-time fluorescent CPA had high specificity, and the limit of detection was 1.06 × 10(3) copies of rice genomic DNA, which could be detected in 40 min. Comparison of real-time fluorescent CPA and conventional polymerase chain reaction (PCR) was also performed. Results revealed that real-time fluorescent CPA had a comparable sensitivity to conventional real-time PCR and had taken a shorter time. In addition, different contents of genetically modified (GM)-contaminated rice seed powder samples were detected for practical application. The result showed real-time fluorescent CPA could detect 0.5 % GM-contaminated samples at least, and the whole reaction could be finished in 35 min. Real-time fluorescent CPA is sensitive enough to monitor labeling systems and provides an attractive method for the detection of GMO.

A highly sensitive and selective fluorescent sensor for detection of sulfide anion based on the steric hindrance effect

NASA Astrophysics Data System (ADS)

Chen, Guanfan; Tang, Mengzhuo; Fu, Xiufang; Cheng, Fenmin; Zou, Xianghua; Wang, Jingpei; Zeng, Rongjin

2018-01-01

Sulfide anions are not only generated as a byproduct from industrial processes but also as a crucial kind of element in biological systems. Therefore, fluorescent probes for detecting sulfide anion with sensitive and selective characters are highly popular. In this study, we report a highly sensitive and selective fluorescent sensor M1 for detection of sulfide anion based on the steric hindrance effect, where the recognition unit, dinitrobenzenesulfonate ester group is linked to aromatic ortho-position in the porphyrin, and correspondingly the fluorescence of fluorescein is efficiently quenched. Compared with the sensors with recognition unit linked to the other aromatic positions, the fluorescent sensor M1 has a lower fluorescence background. Furthermore, the corresponding fluorescence responses (F/F0) of M1 for mercapto amino-acid GSH, Hcy and Cys, were all far lower than the relative fluorescence ratio F/F0 values for S2-. It means that M1 is sensitive and selective to detection of S2-, and has an anti-disturbance ability to the biologically-relevant thiols, GSH, Hcy and Cys, and has the prospect of application in the exact detection of sulfide anions in living organisms. This approach offers some useful insights for realizing sensitive and selective fluorescent turn-on sensing in the detection assays for other analytes.

;Turn-on; fluorescent probe detection of Ca2 + ions and applications to bioimaging

NASA Astrophysics Data System (ADS)

Zhang, Huifang; Yin, Caixia; Liu, Tao; Zhang, Yongbin; Huo, Fangjun

2017-06-01

Ca2 + is intracellular divalent cation with the largest concentration variations and involved in many biological phenomena and often acted as a second messenger in signaling pathway. Therefore, the development of probes for specific Ca2 + detection is of great importance. Herein, a novel turn-on fluorescent probe for the detection of Ca2 + in MeCN-aqueous medium was designed and synthesized. The probe displayed responses to Ca2 + with a fluorescence enhancement at 525 nm, accompanying with a distinct fluorescence change from nearly colorless to bright yellow-green. Besides, the probe exhibited a rapid signal response time (within 25 s), a good linearity range and a lower detection limit (2.70 × 10- 7 M). In addition, the ability of the probe to detect Ca2 + in living cells (HeLa cells) via an enhancement of the fluorescence has also been demonstrated.

Improved detection of soma location and morphology in fluorescence microscopy images of neurons.

PubMed

Kayasandik, Cihan Bilge; Labate, Demetrio

2016-12-01

Automated detection and segmentation of somas in fluorescent images of neurons is a major goal in quantitative studies of neuronal networks, including applications of high-content-screenings where it is required to quantify multiple morphological properties of neurons. Despite recent advances in image processing targeted to neurobiological applications, existing algorithms of soma detection are often unreliable, especially when processing fluorescence image stacks of neuronal cultures. In this paper, we introduce an innovative algorithm for the detection and extraction of somas in fluorescent images of networks of cultured neurons where somas and other structures exist in the same fluorescent channel. Our method relies on a new geometrical descriptor called Directional Ratio and a collection of multiscale orientable filters to quantify the level of local isotropy in an image. To optimize the application of this approach, we introduce a new construction of multiscale anisotropic filters that is implemented by separable convolution. Extensive numerical experiments using 2D and 3D confocal images show that our automated algorithm reliably detects somas, accurately segments them, and separates contiguous ones. We include a detailed comparison with state-of-the-art existing methods to demonstrate that our algorithm is extremely competitive in terms of accuracy, reliability and computational efficiency. Our algorithm will facilitate the development of automated platforms for high content neuron image processing. A Matlab code is released open-source and freely available to the scientific community. Copyright © 2016 Elsevier B.V. All rights reserved.

A "turn-on" fluorescent sensor for ozone detection in ambient air using protein-directed gold nanoclusters.

PubMed

Wu, Di; Qi, Wenjing; Liu, Chun; Zhang, Qing

2017-04-01

A "turn-on" fluorescent sensor for ozone using bovine serum albumin-directed gold nanoclusters (BSA-Au NCs) via energy transfer was developed. The spectral overlap of fluorescent spectrum of BSA-Au NCs with absorption spectrum of indigo carmine (IDS) was utilized. Ozone cleaves C = C bond of IDS and suppresses energy transfer from BSA-Au NCs to IDS. Therefore, this proposed fluorescent sensor is a "turn-on" detection motif. It is the first application of fluorescent nanoclusters in sensitively detecting ozone from 0.2 to 12 μM with the limit of detection of 35 nM (the volume of 500 μL, 1.68 ppb). The proposed fluorescent sensor for ozone is more sensitive and faster (within 2 min) than most methods and is with good selectivity for ozone detection against other reactive oxygen species, reactive nitrogen, or metallic ions. Besides, the proposed method is also utlized in ozone detection in ambient air by monitoring 1 h (60 min) in Qijiang district in Chongqing city. The average of concentration of ozone in ambient air ranges from 44.97 to 52.85 μg/m 3 . The results are compared with the automatic monitoring data provided by Qijiang Environmental Monitoring Station and the relative deviations range, respectively, from 2.1 to 5.6%, which suggests that it is a promising fluorescent sensor for ozone in ambient air. This study not only develops a new model of energy transfer motif using BSA-Au NCs as donor and IDS as acceptor but also expands the application of BSA-Au NCs in environmental science. Graphical abstract A "turn-on" fluorescent sensor for ozone detection using bovine serum albumin-directed gold nanoclusters (BSA-Au NCs) via energy transfer is developed. It is the first time to utilize spectral overlap of fluorescent spectrum of BSA-Au NCs with absorption spectrum of indigo carmine and to achieve fast, sensitive, and selective ozone detection with a limit of detection of down to 35 nM (the volume of 500 μL, 1.68 ppb).

Study of experimental endometriosis using fluorescence of eosin-tamoxifen association

NASA Astrophysics Data System (ADS)

Brogniez, A.; Mordon, Serge R.; Devoisselle, Jean-Marie; Querleu, Denis; Brunetaud, Jean Marc

1993-08-01

The main problem of endometriosis is the detection of microscopic and atypical lesions. The successful destruction of these endometriotic sites depends on their detection. This study aimed to develop a spectrofluorometric method to increase the sensitivity of detection of endometriosis. A surgical-induced endometriosis was performed in ten rabbits. Five weeks later, the fluorescence of these endometriotic lesions was studied after injection of tamoxifen and local application of eosin. This fluorescence was compared with that of healthy broad ligament and that obtained without tamoxifen and without eosin. A spectral analysis showed a specific fluorescence of eosin-tamoxifen association, more intense than autofluorescence and selectively observed within endometriosis.

Capillary electrophoresis hyphenated with UV-native-laser induced fluorescence detection (CE/UV-native-LIF).

PubMed

Couderc, François; Ong-Meang, Varravaddheay; Poinsot, Véréna

2017-01-01

Native laser-induced fluorescence using UV lasers associated to CE offers now a large related literature, for now 30 years. The main works have been performed using very expensive Ar-ion lasers emitting at 257 and 275 nm. They are not affordable for routine analyses, but have numerous applications such as protein, catecholamine, and indolamine analysis. Some other lasers such as HeCd 325 nm have been used but only for few applications. Diode lasers, emitting at 266 nm, cheaper, are extensively used for the same topics, even if the obtained sensitivity is lower than the one observed using the costly UV-Ar-ion lasers. This review presents various CE or microchips applications and different UV lasers used for the excitation of native fluorescence. We showed that CE/Native UV laser induced fluorescence detection is very sensitive for detection as well as small aromatic biomolecules than proteins containing Trp and Tyr amino acids. Moreover, it is a simple way to analyze biomolecules without derivatization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real time detection of ESKAPE pathogens by a nitroreductase-triggered fluorescence turn-on probe.

PubMed

Xu, Shengnan; Wang, Qinghua; Zhang, Qingyang; Zhang, Leilei; Zuo, Limin; Jiang, Jian-Dong; Hu, Hai-Yu

2017-10-18

The identification of bacterial pathogens is the critical first step in conquering infection diseases. A novel turn-on fluorescent probe for the selective sensing of nitroreductase (NTR) activity and its initial applications in rapid, real-time detection and identification of ESKAPE pathogens have been reported.

Smartphone Cortex Controlled Real-Time Image Processing and Reprocessing for Concentration Independent LED Induced Fluorescence Detection in Capillary Electrophoresis.

PubMed

Szarka, Mate; Guttman, Andras

2017-10-17

We present the application of a smartphone anatomy based technology in the field of liquid phase bioseparations, particularly in capillary electrophoresis. A simple capillary electrophoresis system was built with LED induced fluorescence detection and a credit card sized minicomputer to prove the concept of real time fluorescent imaging (zone adjustable time-lapse fluorescence image processor) and separation controller. The system was evaluated by analyzing under- and overloaded aminopyrenetrisulfonate (APTS)-labeled oligosaccharide samples. The open source software based image processing tool allowed undistorted signal modulation (reprocessing) if the signal was inappropriate for the actual detection system settings (too low or too high). The novel smart detection tool for fluorescently labeled biomolecules greatly expands dynamic range and enables retrospective correction for injections with unsuitable signal levels without the necessity to repeat the analysis.

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

PubMed

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.

Simultaneous multicolor imaging of wide-field epi-fluorescence microscopy with four-bucket detection

PubMed Central

Park, Kwan Seob; Kim, Dong Uk; Lee, Jooran; Kim, Geon Hee; Chang, Ki Soo

2016-01-01

We demonstrate simultaneous imaging of multiple fluorophores using wide-field epi-fluorescence microscopy with a monochrome camera. The intensities of the three lasers are modulated by a sinusoidal waveform in order to excite each fluorophore with the same modulation frequency and a different time-delay. Then, the modulated fluorescence emissions are simultaneously detected by a camera operating at four times the excitation frequency. We show that two different fluorescence beads having crosstalk can be clearly separated using digital processing based on the phase information. In addition, multiple organelles within multi-stained single cells are shown with the phase mapping method, demonstrating an improved dynamic range and contrast compared to the conventional fluorescence image. These findings suggest that wide-field epi-fluorescence microscopy with four-bucket detection could be utilized for high-contrast multicolor imaging applications such as drug delivery and fluorescence in situ hybridization. PMID:27375944

A PDMS-based cylindrical hybrid lens for enhanced fluorescence detection in microfluidic systems.

PubMed

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.

Development of Functional Fluorescent Molecular Probes for the Detection of Biological Substances

PubMed Central

Suzuki, Yoshio; Yokoyama, Kenji

2015-01-01

This review is confined to sensors that use fluorescence to transmit biochemical information. Fluorescence is, by far, the most frequently exploited phenomenon for chemical sensors and biosensors. Parameters that define the application of such sensors include intensity, decay time, anisotropy, quenching efficiency, and luminescence energy transfer. To achieve selective (bio)molecular recognition based on these fluorescence phenomena, various fluorescent elements such as small organic molecules, enzymes, antibodies, and oligonucleotides have been designed and synthesized over the past decades. This review describes the immense variety of fluorescent probes that have been designed for the recognitions of ions, small and large molecules, and their biological applications in terms of intracellular fluorescent imaging techniques. PMID:26095660

Laser induced fluorescence of biochemical for UV LIDAR application.

PubMed

Gupta, L; Sharma, R C; Razdan, A K; Maini, A K

2014-05-01

Laser induced fluorescence spectroscopy in the ultraviolet regime has been used for the detection of biochemical through a fiber coupled CCD detector from a distance of 2 m. The effect of concentration and laser excitation energy on the fluorescence spectra of nicotinamide adenine dinucleotide (NADH) has been investigated. The signature fluorescence peak of NADH was centred about 460 nm. At lower concentration Raman peak centred at 405 nm was also observed. The origin of this peak has been discussed. Detection limit with the proposed set up is found to be 1 ppm.

An integrated fluorescence detection system in poly(dimethylsiloxane) for microfluidic applications.

PubMed

Chabinyc, M L; Chiu, D T; McDonald, J C; Stroock, A D; Christian, J F; Karger, A M; Whitesides, G M

2001-09-15

This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-microm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state microAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 microm) colored polycarbonate filter was placed on the top of the embedded microAPD to absorb scattered excitation light before it reached the detector. The microAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (approximately 200 microm) of the microAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the microAPD (30 microm) matched the dimensions of the channels (50 microm). A blue light-emitting diode was used for fluorescence excitation. The microAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (approximately 25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

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

NASA Astrophysics Data System (ADS)

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

2014-09-01

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.

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

PubMed Central

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

Applications of fluorescence spectroscopy to problems of food safety: detection of fecal contamination and of the presence of central nervous system tissue and diagnosis of neurological disease

NASA Astrophysics Data System (ADS)

Adhikary, Ramkrishna; Bose, Sayantan; Casey, Thomas A.; Gapsch, Al; Rasmussen, Mark A.; Petrich, Jacob W.

2010-02-01

Applications of fluorescence spectroscopy that enable the real-time or rapid detection of fecal contamination on beef carcasses and the presence of central nervous system tissue in meat products are discussed. The former is achieved by employing spectroscopic signatures of chlorophyll metabolites; the latter, by exploiting the characteristic structure and intensity of lipofuscin in central nervous system tissue. The success of these techniques has led us to investigate the possibility of diagnosing scrapie in sheep by obtaining fluorescence spectra of the retina. Crucial to this diagnosis is the ability to obtain baseline correlations of lipofuscin fluorescence with age. A murine model was employed as a proof of principle of this correlation.

Green route for synthesis of multifunctional fluorescent carbon dots from Tulsi leaves and its application as Cr(VI) sensors, bio-imaging and patterning agents.

PubMed

Bhatt, Shreya; Bhatt, Madhuri; Kumar, Anshu; Vyas, Gaurav; Gajaria, Tejal; Paul, Parimal

2018-07-01

We report a one pot green strategy for the synthesis of carbon dots using tulsi leaves and their potential application in sensing of Cr(VI) selectively. The detection mechanism is based on the phenomenon called inner filter effect (IFE) and a good linear static quenching was observed in the range of 1.6 μM to 50 μM with a detection limit of 4.5 ppb. The reversible switching in fluorescence has been tested and a good recovery in fluorescence was observed up to three consecutive cycles upon addition of ascorbic acid as reducing agent. Also the low toxicity, high fluorescence and photostabilty of the CDs make them excellent imaging and patterning agent. The acid and alkali resistant property of these CDs makes it suitable for real sample analysis. The fluorescent CDs were applied for successful detection of Cr(VI) in water with spike-recoveries ranging from 93 to 99%. Copyright © 2018 Elsevier B.V. All rights reserved.

New water soluble Hg2 + selective fluorescent calix[4]arenes: Synthesis and application in living cells imaging

NASA Astrophysics Data System (ADS)

Oguz, Mehmet; Bhatti, Asif Ali; Karakurt, Serdar; Aktas, Mehmet; Yilmaz, Mustafa

2017-01-01

The present study demonstrates the synthesis of water-soluble fluorescent calix[4]arenes (6 and 7) and its application in living cell imaging for Hg2 + detection at a low level. The synthesized fluorescent ligands 6 and 7 were characterized by 1H NMR technique. The fluorescent study showed both water soluble ligands were Hg2 + selective and follow photo-induced electron transfer (PET) process. From the fluorimeter titration experiment detection limit was calculated as 1.14 × 10- 5 and 3.42 × 10- 5 for ligand 6 and 7, respectively. From the Benesi-Hildebrand plot binding constant values were evaluated as 666.7 and 733.3 M- 1 for 6 and 7, respectively. The interactions between ligands 6 and 7 and Hg2 + were also demonstrated in living cells, SW-620, using Fluorescent Cell Imager. While ligands 6 and 7 alone show fluorescent properties, they loss their action with the presence of Hg2 + in SW-620 cells.

New fluorescence techniques for high-throughput drug discovery.

PubMed

Jäger, S; Brand, L; Eggeling, C

2003-12-01

The rapid increase of compound libraries as well as new targets emerging from the Human Genome Project require constant progress in pharmaceutical research. An important tool is High-Throughput Screening (HTS), which has evolved as an indispensable instrument in the pre-clinical target-to-IND (Investigational New Drug) discovery process. HTS requires machinery, which is able to test more than 100,000 potential drug candidates per day with respect to a specific biological activity. This calls for certain experimental demands especially with respect to sensitivity, speed, and statistical accuracy, which are fulfilled by using fluorescence technology instrumentation. In particular the recently developed family of fluorescence techniques, FIDA (Fluorescence Intensity Distribution Analysis), which is based on confocal single-molecule detection, has opened up a new field of HTS applications. This report describes the application of these new techniques as well as of common fluorescence techniques--such as confocal fluorescence lifetime and anisotropy--to HTS. It gives experimental examples and presents advantages and disadvantages of each method. In addition the most common artifacts (auto-fluorescence or quenching by the drug candidates) emerging from the fluorescence detection techniques are highlighted and correction methods for confocal fluorescence read-outs are presented, which are able to circumvent this deficiency.

Detection of reactive oxygen species in mainstream cigarette smoke by a fluorescent probe

NASA Astrophysics Data System (ADS)

Liu, Li; Xu, Shi-jie; Li, Song-zhan

2009-07-01

A mass of reactive oxygen species(ROS) are produced in the process of smoking. Superfluous ROS can induce the oxidative stress in organism, which will cause irreversible damage to cells. Fluorescent probe is taken as a marker of oxidative stress in biology and has been applied to ROS detection in the field of biology and chemistry for high sensitivity, high simplicity of data collection and high resolution. As one type of fluorescent probe, dihydrorhodamine 6G (dR6G) will be oxidized to the fluorescent rhodamine 6G, which could be used to detect ROS in mainstream cigarette smoke. We investigated the action mechanism of ROS on dR6G, built up the standard curve of R6G fluorescence intensity with its content, achieved the variation pattern of R6G fluorescence intensity with ROS content in mainstream cigarette smoke and detected the contents of ROS from the 4 types of cigarettes purchased in market. The result shows that the amount of ROS has close relationship with the types of tobacco and cigarette production technology. Compared with other detecting methods such as electronic spin resonance(ESR), chromatography and mass spectrometry, this detection method by the fluorescent probe has higher efficiency and sensitivity and will have wide applications in the ROS detection field.

NIR fluorescent dyes: versatile vehicles for marker and probe applications

NASA Astrophysics Data System (ADS)

Patonay, Gabor; Chapman, Gala; Beckford, Garfield; Henary, Maged

2013-02-01

The use of the NIR spectral region (650-900 nm) is advantageous due to the inherently lower background interference and the high molar absorptivities of NIR chromophores. Near-Infrared (NIR) dyes are increasingly used in the biological and medical field. The binding characteristics of NIR dyes to biomolecules are possibly controlled by several factors, including hydrophobicity, size and charge just to mention a few parameters. Binding characteristics of symmetric carbocyanines and found that the hydrophobic nature of the NIR dye is only partially responsible for the binding strength. Upon binding to biomolecules significant fluorescence enhancement can be observed for symmetrical carbocyanines. This fluorescence amplification facilitates the detection of the NIR dye and enhances its utility as NIR reporter. This manuscript discusses some probe and marker applications of such NIR fluorescent dyes. One application discussed here is the use of NIR dyes as markers. For labeling applications the fluorescence intensity of the NIR fluorescent label can significantly be increased by enclosing several dye molecules in nanoparticles. To decrease self quenching dyes that have relatively large Stokes' shift needs to be used. This is achieved by substituting meso position halogens with amino moiety. This substitution can also serve as a linker to covalently attach the dye molecule to the nanoparticle backbone. We report here on the preparation of NIR fluorescent silica nanoparticles. Silica nanoparticles that are modified with aminoreactive moieties can be used as bright fluorescent labels in bioanalytical applications. A new bioanalytical technique to detect and monitor the catalytic activity of the sulfur assimilating enzyme using NIR dyes is reported as well. In this spectroscopic bioanalytical assay a family of Fischer based n-butyl sulfonate substituted dyes that exhibit distinct variation in absorbance and fluorescence properties and strong binding to serum albumin as its sulfonic acid moiety is modified to less water soluble moiety was identified. In polar solvents, these water soluble compounds are strongly fluorescent, however form the less soluble aggregated species with virtual loss of fluorescence when the sulfonate groups are cleaved by enzymatic activity to form the corresponding straight chain alkyl aldehyde derivatives. To achieve this conversion in vitro photo-reduced riboflavin mononucleotide (FMN) with a glucose/ glucose-oxygenase oxygen scavenging system was utilized. The reduced FMN serves as a key substrate in the enzymatic desulfonation. Once the FMNH2 was produced the desulfonation reaction was characterized by using Laser Induced Fluorescence Capillary Zone Electropheresis (LIF-CZE). This method can be utilized as an assay to detect the enzyme activity in vitro with the possibilities of in vivo applications.

Multispectral fluorescence imaging techniques for nondestructive food safety inspection

NASA Astrophysics Data System (ADS)

Kim, Moon S.; Lefcourt, Alan M.; Chen, Yud-Ren

2004-03-01

The use of spectral sensing has gained acceptance as a rapid means for nondestructive inspection of postharvest food produce. Current technologies generally use color or a single wavelength camera technology. The applicability and sensitivity of these techniques can be expanded through the use of multiple wavelengths. Reflectance in the Vis/NIR is the prevalent spectral technique. Fluorescence, compared to reflectance, is regarded as a more sensitive technique due to its dynamic responses to subtle changes in biological entities. Our laboratory has been exploring fluorescence as a potential means for detection of quality and wholesomeness of food products. Applications of fluorescence sensing require an understanding of the spectral characteristics emanating from constituents and potential contaminants. A number of factors affecting fluorescence emission characteristics are discussed. Because of relatively low fluorescence quantum yield from biological samples, a system with a powerful pulse light source such as a laser coupled with a gated detection device is used to harvest fluorescence, in the presence of ambient light. Several fluorescence sensor platforms developed in our laboratory, including hyperspectral imaging, and laser-induced fluorescence (LIF) and steady-state fluorescence imaging systems with multispectral capabilities are presented. We demonstrate the potential uses of recently developed fluorescence imaging platforms in food safety inspection of apples contaminated with animal feces.

Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform

NASA Astrophysics Data System (ADS)

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 (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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05839b

A chromogenic and fluorogenic rhodol-based chemosensor for hydrazine detection and its application in live cell bioimaging.

PubMed

Tiensomjitr, Khomsan; Noorat, Rattha; Chomngam, Sinchai; Wechakorn, Kanokorn; Prabpai, Samran; Kanjanasirirat, Phongthon; Pewkliang, Yongyut; Borwornpinyo, Suparerk; Kongsaeree, Palangpon

2018-04-15

A rhodol-based fluorescent probe has been developed as a selective hydrazine chemosensor using levulinate as a recognition site. The rhodol levulinate probe (RL) demonstrated high selectivity and sensitivity toward hydrazine among other molecules. The chromogenic response of RL solution to hydrazine from colorless to pink could be readily observed by the naked eye, while strong fluorescence emission could be monitored upon excitation at 525 nm. The detection process occurred via a ring-opening process of the spirolactone initiated by hydrazinolysis, triggering the fluorescence emission with a 53-fold enhancement. The probe rapidly reacted with hydrazine in aqueous medium with the detection limit of 26 nM (0.83 ppb), lower than the threshold limit value (TLV) of 10 ppb suggested by the U.S. Environmental Protection Agency. Furthermore, RL-impregnated paper strips could detect hydrazine vapor. For biological applicability of RL, its membrane-permeable property led to bioimaging of hydrazine in live HepG2 cells by confocal fluorescence microscopy. Copyright © 2018 Elsevier B.V. All rights reserved.

Light emitting diode, photodiode-based fluorescence detection system for DNA analysis with microchip electrophoresis.

PubMed

Hall, Gordon H; Glerum, D Moira; Backhouse, Christopher J

2016-02-01

Electrophoretic separation of fluorescently end-labeled DNA after a PCR serves as a gold standard in genetic diagnostics. Because of their size and cost, instruments for this type of analysis have had limited market uptake, particularly for point-of-care applications. This might be changed through a higher level of system integration and lower instrument costs that can be realized through the use of LEDs for excitation and photodiodes for detection--if they provide sufficient sensitivity. Here, we demonstrate an optimized microchip electrophoresis instrument using polymeric fluidic chips with fluorescence detection of end-labeled DNA with a LOD of 0.15 nM of Alexa Fluor 532. This represents orders of magnitude improvement over previously reported instruments of this type. We demonstrate the system with an electrophoretic separation of two PCR products and their respective primers. We believe that this is the first LED-induced fluorescence microchip electrophoresis system with photodiode-based detection that could be used for standard applications of PCR and electrophoresis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Introducing Ratiometric Fluorescence to MnO2 Nanosheet-Based Biosensing: A Simple, Label-Free Ratiometric Fluorescent Sensor Programmed by Cascade Logic Circuit for Ultrasensitive GSH Detection.

PubMed

Fan, Daoqing; Shang, Changshuai; Gu, Wenling; Wang, Erkang; Dong, Shaojun

2017-08-09

Glutathione (GSH) plays crucial roles in various biological functions, the level alterations of which have been linked to varieties of diseases. Herein, we for the first time expanded the application of oxidase-like property of MnO 2 nanosheet (MnO 2 NS) to fluorescent substrates of peroxidase. Different from previously reported fluorescent quenching phenomena, we found that MnO 2 NS could not only largely quench the fluorescence of highly fluorescent Scopoletin (SC) but also surprisingly enhance that of nonfluorescent Amplex Red (AR) via oxidation reaction. If MnO 2 NS is premixed with GSH, it will be reduced to Mn 2+ and lose the oxidase-like property, accompanied by subsequent increase in SC's fluorescence and decrease in AR's. On the basis of the above mechanism, we construct the first MnO 2 NS-based ratiometric fluorescent sensor for ultrasensitive and selective detection of GSH. Notably, this ratiometric sensor is programmed by the cascade logic circuit (an INHIBIT gate cascade with a 1 to 2 decoder). And a linear relationship between ratiometric fluorescent intensities of the two substrates and logarithmic values of GSH's concentrations is obtained. The detection limit of GSH is as low as 6.7 nM, which is much lower than previous ratiometric fluorescent sensors, and the lowest MnO 2 NS-based fluorescent GSH sensor reported so far. Furthermore, this sensor is simple, label-free, and low-cost; it also presents excellent applicability in human serum samples.

A synthesis of fluorescent starch based on carbon nanoparticles for fingerprints detection

NASA Astrophysics Data System (ADS)

Li, Hongren; Guo, Xingjia; Liu, Jun; Li, Feng

2016-10-01

A pyrolysis method for synthesizing carbon nanoparticles (CNPs) were developed by using malic acid and ammonium oxalate as raw materials. The incorporation of a minor amount of carbon nanoparticles into starch powder imparts remarkable color-tunability. Based on this phenomenon, an environment friendly fluorescent starch powder for detecting latent fingerprints in non-porous surfaces was prepared. The fingerprints on different non-porous surfaces developed with this powder showed very good fluorescent images under ultraviolet excitation. The method using fluorescent starch powder as fluorescent marks is simple, rapid and green. Experimental results illustrated the effectiveness of proposed methods, enabling its practical applications in forensic sciences.

Photonic crystal enhanced fluorescence immunoassay on diatom biosilica.

PubMed

Squire, Kenneth; Kong, Xianming; LeDuff, Paul; Rorrer, Gregory L; Wang, Alan X

2018-05-16

Fluorescence biosensing is one of the most established biosensing methods, particularly fluorescence spectroscopy and microscopy. These are two highly sensitive techniques but require high grade electronics and optics to achieve the desired sensitivity. Efforts have been made to implement these methods using consumer grade electronics and simple optical setups for applications such as point-of-care diagnostics, but the sensitivity inherently suffers. Sensing substrates, capable of enhancing fluorescence are thus needed to achieve high sensitivity for such applications. In this paper, we demonstrate a photonic crystal-enhanced fluorescence immunoassay biosensor using diatom biosilica, which consists of silica frustules with sub-100 nm periodic pores. Utilizing the enhanced local optical field, the Purcell effect and increased surface area from the diatom photonic crystals, we create ultrasensitive immunoassay biosensors that can significantly enhance fluorescence spectroscopy as well as fluorescence imaging. Using standard antibody-antigen-labeled antibody immunoassay protocol, we experimentally achieved 100× and 10× better detection limit with fluorescence spectroscopy and fluorescence imaging respectively. The limit of detection of the mouse IgG goes down to 10 -16 M (14 fg/mL) and 10 -15 M (140 fg/mL) for the two respective detection modalities, virtually sensing a single mouse IgG molecule on each diatom frustule. The effectively enhanced fluorescence imaging in conjunction with the simple hot-spot counting analysis method used in this paper proves the great potential of diatom fluorescence immunoassay for point-of-care biosensing. Scanning electron microscope image of biosilica diatom frustule that enables significant enhancement of fluorescence spectroscopy and fluorescence image. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Magnetofluorescent nanocomposites and quantum dots used for optimal application in magnetic fluorescence-linked immunoassay.

PubMed

Tsai, H Y; Li, S Y; Fuh, C Bor

2018-03-01

Magnetofluorescent nanocomposites with optimal magnetic and fluorescent properties were prepared and characterized by combining magnetic nanoparticles (iron oxide@polymethyl methacrylate) with fluorescent nanoparticles (rhodamine 6G@mSiO 2 ). Experimental parameters were optimized to produce nanocomposites with high magnetic susceptibility and fluorescence intensity. The detection of a model biomarker (alpha-fetoprotein) was used to demonstrate the feasibility of applying the magnetofluorescent nanocomposites combined with quantum dots and using magnetic fluorescence-linked immunoassay. The magnetofluorescent nanocomposites enable efficient mixing, fast re-concentration, and nanoparticle quantization for optimal reactions. Biofunctional quantum dots were used to confirm the alpha-fetoprotein (AFP) content in sandwich immunoassay after mixing and washing. The analysis time was only one third that required in ELISA. The detection limit was 0.2 pg mL -1 , and the linear range was 0.68 pg mL -1 -6.8 ng mL -1 . This detection limit is lower, and the linear range is wider than those of ELISA and other methods. The measurements made using the proposed method differed by less than 13% from those obtained using ELISA for four AFP concentrations (0.03, 0.15, 0.75, and 3.75 ng mL -1 ). The proposed method has a considerable potential for biomarker detection in various analytical and biomedical applications. Graphical abstract Magnetofluorescent nanocomposites combined with fluorescent quantum dots were used in magnetic fluorescence-linked immunoassay.

A new high selective and sensitive turn-on fluorescent and ratiometric absorption chemosensor for Cu2+ based on benzimidazole in aqueous solution and its application in live cell.

PubMed

Bing, Qijing; Wang, Lin; Li, Donglin; Wang, Guang

2018-09-05

A new benzimidazole base turn-on fluorescent and ratiometric absorption chemosensor (L) bearing bidentate ligand for detection of Cu 2+ was designed and synthesized. Fluorescence and UV-vis spectra studies demonstrated that L can detect Cu 2+ ions in aqueous solution using fluorescence enhancement and ratiometric absorption sensing over a wide pH range. Both fluorescent and ratiometric absorption sensing of L for Cu 2+ possessed high selectivity and sensitivity over other competitive metal ions and had low detection limit. Job's plot, mass spectra and DFT calculation indicated the sensing mechanism is the complex formation between L and Cu 2+ with 1:2 stoichiometry. Fluorescence images of HepG2 in the absence and presence of Cu 2+ displayed L had cell permeability and detection ability for Cu 2+ in live cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Near-Infrared Fluorescent Turn-on Probe with a Remarkable Large Stokes Shift for Imaging Selenocysteine in Living Cells and Animals.

PubMed

Feng, Weiyong; Li, Meixing; Sun, Yao; Feng, Guoqiang

2017-06-06

Selenocysteine (Sec) is the 21st naturally occurring amino acid and has emerged as an important sensing target in recent years. However, fluorescent detection of Sec in living systems is challenging. To date, very few fluorescent Sec probes have been reported and most of them respond fluorescence to Sec in the visible region. In this paper, a very promising near-infrared fluorescent probe for Sec was developed. This probe works in aqueous solution over a wide pH range under mild conditions and can be used for rapid, highly selective and sensitive detection of Sec with significant near-infrared fluorescent turn-on signal changes. In addition, it features a remarkable large Stokes shift (192 nm) and a low detection limit (60 nM) for Sec with a wide linear range (0-70 μM). Moreover, this probe can be conveniently used to detect Sec in serum samples, living cells, and animals, indicating it holds great promise for biological applications.

Exciton-controlled fluorescence: application to hybridization-sensitive fluorescent DNA probe.

PubMed

Okamoto, Akimitsu; Ikeda, Shuji; Kubota, Takeshi; Yuki, Mizue; Yanagisawa, Hiroyuki

2009-01-01

A hybridization-sensitive fluorescent probe has been designed for nucleic acid detection, using the concept of fluorescence quenching caused by the intramolecular excitonic interaction of fluorescence dyes. We synthesized a doubly thiazole orange-labeled nucleotide showing high fluorescence intensity for a hybrid with the target nucleic acid and effective quenching for the single-stranded state. This exciton-controlled fluorescent probe was applied to living HeLa cells using microinjection to visualize intracellular mRNA localization. Immediately after injection of the probe into the cell, fluorescence was observed from the probe hybridizing with the target RNA. This fluorescence rapidly decreased upon addition of a competitor DNA. Multicoloring of this probe resulted in the simple simultaneous detection of plural target nucleic acid sequences. This probe realized a large, rapid, reversible change in fluorescence intensity in sensitive response to the amount of target nucleic acid, and facilitated spatiotemporal monitoring of the behavior of intracellular RNA.

Detection of Thrombin Based on Fluorescence Energy Transfer between Semiconducting Polymer Dots and BHQ-Labelled Aptamers.

PubMed

Liu, Yizhang; Jiang, Xuekai; Cao, Wenfeng; Sun, Junyong; Gao, Feng

2018-02-14

Carboxyl-functionalized semiconducting polymer dots (Pdots) were synthesized as an energy donor by the nanoprecipitation method. A black hole quenching dye (BHQ-labelled thrombin aptamers) was used as the energy acceptor, and fluorescence resonance energy transfer between the aptamers and Pdots was used for fluorescence quenching of the Pdots. The addition of thrombin restored the fluorescence intensity. Under the optimized experimental conditions, the fluorescence of the system was restored to the maximum when the concentration of thrombin reached 130 nM, with a linear range of 0-50 nM (R² = 0.990) and a detection limit of 0.33 nM. This sensor was less disturbed by impurities, showing good specificity and signal response to thrombin, with good application in actual samples. The detection of human serum showed good linearity in the range of 0-30 nM (R² = 0.997), with a detection limit of 0.56 nM and a recovery rate of 96.2-104.1%, indicating that this fluorescence sensor can be used for the detection of thrombin content in human serum.

Single molecule tools for enzymology, structural biology, systems biology and nanotechnology: an update

PubMed Central

Widom, Julia R.; Dhakal, Soma; Heinicke, Laurie A.; Walter, Nils G.

2015-01-01

Toxicology is the highly interdisciplinary field studying the adverse effects of chemicals on living organisms. It requires sensitive tools to detect such effects. After their initial implementation during the 1990s, single-molecule fluorescence detection tools were quickly recognized for their potential to contribute greatly to many different areas of scientific inquiry. In the intervening time, technical advances in the field have generated ever-improving spatial and temporal resolution, and have enabled the application of single-molecule fluorescence to increasingly complex systems, such as live cells. In this review, we give an overview of the optical components necessary to implement the most common versions of single-molecule fluorescence detection. We then discuss current applications to enzymology and structural studies, systems biology, and nanotechnology, presenting the technical considerations that are unique to each area of study, along with noteworthy recent results. We also highlight future directions that have the potential to revolutionize these areas of study by further exploiting the capabilities of single-molecule fluorescence microscopy. PMID:25212907

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Zongchao; Wang, Fengqin, E-mail: wangfengqin@tjpu.edu.cn; Lin, Xiangyi

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{sub 3}L{sub 3}(DMF){sub 2} (1) and Zn{sub 3}L{sub 3}(DMA){sub 2}(H{sub 2}O){sub 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{sup 3+} and Al{sup 3+} by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significantmore » fluorescence quenching effect for Fe{sup 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{sup 3+} or Al{sup 3+}.« less

Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform.

PubMed

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.

Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

NASA Astrophysics Data System (ADS)

Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

2017-04-01

Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

Disposable pen-shaped capillary gel electrophoresis cartridge for fluorescence detection of bio-molecules

NASA Astrophysics Data System (ADS)

Amirkhanian, Varoujan; Tsai, Shou-Kuan

2014-03-01

We introduce a novel and cost-effective capillary gel electrophoresis (CGE) system utilizing disposable pen-shaped gelcartridges for highly efficient, high speed, high throughput fluorescence detection of bio-molecules. The CGE system has been integrated with dual excitation and emission optical-fibers with micro-ball end design for fluorescence detection of bio-molecules separated and detected in a disposable pen-shaped capillary gel electrophoresis cartridge. The high-performance capillary gel electrophoresis (CGE) analyzer has been optimized for glycoprotein analysis type applications. Using commercially available labeling agent such as ANTS (8-aminonapthalene-1,3,6- trisulfonate) as an indicator, the capillary gel electrophoresis-based glycan analyzer provides high detection sensitivity and high resolving power in 2-5 minutes of separations. The system can hold total of 96 samples, which can be automatically analyzed within 4-5 hours. This affordable fiber optic based fluorescence detection system provides fast run times (4 minutes vs. 20 minutes with other CE systems), provides improved peak resolution, good linear dynamic range and reproducible migration times, that can be used in laboratories for high speed glycan (N-glycan) profiling applications. The CGE-based glycan analyzer will significantly increase the pace at which glycoprotein research is performed in the labs, saving hours of preparation time and assuring accurate, consistent and economical results.

Through-barrier detection of explosive components for security screening applications

NASA Astrophysics Data System (ADS)

Lee, Linda; Frisby, Alex; Mansson, Ralph; Hopkins, Rebecca J.

2011-11-01

The detection of materials through containers is a vital capability for security screening applications at high risk locations, such as airports and checkpoints. Current detection procedures require suspect containers to be opened and the contents sampled, which is laborious and potentially hazardous to the operator. The capability to detect through-barrier would overcome these issues. Spatially Offset Raman Spectroscopy (SORS) is an innovative spectroscopic technique that avoids fluorescence and Raman scatter from containers, which can mask the Raman signature from the sample. This novel approach enables noninvasive detection of hazardous and benign materials through a wider range of container materials than is possible using conventional Raman spectroscopy. SORS spectra were acquired from explosive compounds and benign materials within a range of coloured glass and plastic containers. The SORS spectra were compared to the reference Raman signatures of the materials studied. Two data analysis methods were then applied to the resultant data to investigate the ability of SORS to detect the target materials through the barriers tested. Furthermore, the potential for reduction of sample fluorescence was investigated by using longer excitation wavelength (1064 nm) than is typically used in commercially available Raman instruments that use silicon detector technology. For some fluorescent samples, Raman spectral features that were masked by fluorescence at 785 nm were revealed at 1064 nm.

Multimodal wide-field two-photon excitation imaging: characterization of the technique for in vivo applications

PubMed Central

Hwang, Jae Youn; Wachsmann-Hogiu, Sebastian; Ramanujan, V Krishnan; Nowatzyk, Andreas G.; Koronyo, Yosef; Medina-Kauwe, Lali K.; Gross, Zeev; Gray, Harry B.; Farkas, Daniel L.

2011-01-01

We report fast, non-scanning, wide-field two-photon fluorescence excitation with spectral and lifetime detection for in vivo biomedical applications. We determined the optical characteristics of the technique, developed a Gaussian flat-field correction method to reduce artifacts resulting from non-uniform excitation such that contrast is enhanced, and showed that it can be used for ex vivo and in vivo cellular-level imaging. Two applications were demonstrated: (i) ex vivo measurements of beta-amyloid plaques in retinas of transgenic mice, and (ii) in vivo imaging of sulfonated gallium(III) corroles injected into tumors. We demonstrate that wide-field two photon fluorescence excitation with flat-field correction provides more penetration depth as well as better contrast and axial resolution than the corresponding one-photon wide field excitation for the same dye. Importantly, when this technique is used together with spectral and fluorescence lifetime detection modules, it offers improved discrimination between fluorescence from molecules of interest and autofluorescence, with higher sensitivity and specificity for in vivo applications. PMID:21339880

Detection of iron atoms by emission spectroscopy and laser-induced fluorescence in solid propellant flames.

PubMed

Vilmart, G; Dorval, N; Orain, M; Lambert, D; Devillers, R; Fabignon, Y; Attal-Tretout, B; Bresson, A

2018-05-10

Planar laser-induced fluorescence on atomic iron is investigated in this paper, and a measurement strategy is proposed to monitor the fluorescence of iron atoms with good sensitivity. A model is proposed to fit the experimental fluorescence spectra, and good agreement is found between simulated and experimental spectra. Emission and laser-induced fluorescence measurements are performed in the flames of ammonium perchlorate composite propellants containing iron-based catalysts. A fluorescence signal from iron atoms after excitation at 248 nm is observed for the first time in propellant flames. Images of the spatial distribution of iron atoms are recorded in the flame in which turbulent structures are generated. Iron fluorescence is detected up to 1.0 MPa, which opens the way to application in propellant combustion.

Detection of melanomas by digital imaging of spectrally resolved UV light-induced autofluorescence of human skin

NASA Astrophysics Data System (ADS)

Chwirot, B. W.; Chwirot, S.; Jedrzejczyk, W.; Redzinski, J.; Raczynska, A. M.; Telega, K.

2001-07-01

We studied spectral and spatial distributions of the intensity of the ultraviolet light-excited fluorescence of human skin. Our studied performed in situ in 162 patients with malignant and non-malignant skin lesions resulted in a new method of detecting melanomas in situ using digital imaging of the spectrally resolved fluorescence. With our diagnostic algorithm we could successfully detect 88.5% of the cases of melanoma in the group of patients subject to examinations with the fluorescence method. A patent application for the method has been submitted to the Patent Office in Warsaw.

Selective and Sensitive Fluorescent Detection of Picric Acid by New Pyrene and Anthracene Based Copper Complexes.

PubMed

Reddy, Kumbam Lingeshwar; Kumar, Anabathula Manoj; Dhir, Abhimanew; Krishnan, Venkata

2016-11-01

New pyrene and anthracene based copper complexes 4 and 7 respectively were designed, synthesized and characterized. The fluorescence behaviour of both 4 and 7 were evaluated towards nitro aromatics and anions. Both 4 and 7 possess high selectivity for the detection of well-known explosive picric acid (PA) by showing maximum fluorescence affinity. Furthermore, complex 4 showed similar sensing efficiency towards PA at different pH ranges. It was also used for real world applications, as illustrated by the very fast detection of PA from soil samples observed directly by naked eye.

Improved murine glioma detection following modified diet and photobleaching of skin PpIX fluorescence

NASA Astrophysics Data System (ADS)

Gibbs, Summer L.; O'Hara, Julia A.; Hoopes, P. Jack; Pogue, Brian W.

2007-02-01

The Aminolevulinic Acid (ALA) - Protoporphyrin IX (PpIX) system is unique in the world of photosensitizers in that the prodrug ALA is enzymatically transformed via the tissue of interest into fluorescently detectable levels of PpIX. This system can be used to monitor cellular metabolism of tumor tissue for applications such as therapy monitoring. Detecting PpIX fluorescence noninvasively has proven difficult due to the high levels of PpIX produced in the skin compared to other tissue both with and without ALA administration. In the current study, methods to decrease skin PpIX autofluorescence and skin PpIX fluorescence following ALA administration have been examined. Use of a purified diet is found to decrease both skin PpIX autofluorescence and skin PpIX fluorescence following ALA administration, while addition of a broad spectrum antibiotic to the water shows little effect. Following ALA administration, improved brain tumor detection is seen when skin PpIX fluorescence is photobleached via blue light prior to transmission spectroscopic measurements of tumor bearing and control animals. Both of these methods to decrease skin PpIX autofluorescence and skin PpIX fluorescence following ALA administration are shown to have a large effect on the ability to detect tumor tissue PpIX fluorescence noninvasively in vivo.

Intraoperative Identification of the Parathyroid Gland with a Fluorescence Detection System.

PubMed

Shinden, Yoshiaki; Nakajo, Akihiro; Arima, Hideo; Tanoue, Kiyonori; Hirata, Munetsugu; Kijima, Yuko; Maemura, Kosei; Natsugoe, Shoji

2017-06-01

Intraoperative identification of the difficult-to-spot parathyroid gland is critical during surgery for thyroid and parathyroid disease. Recently, intrinsic fluorescence of the parathyroid gland was identified, and a new method was developed for intraoperative detection of the parathyroid with an original fluorescent detection apparatus. Here, we describe a method for intraoperative detection of the parathyroid using a ready-made photodynamic eye (PDE) system without any fluorescent dye or contrast agents. Seventeen patients who underwent surgical treatment for thyroid or parathyroid disease at Kagoshima University Hospital were enrolled in this study. Intrinsic fluorescence of various tissues was detected with the PDE system. Intraoperative in vivo and ex vivo intrinsic fluorescence of the parathyroid, thyroid, lymph nodes and fat tissues was measured and analyzed. The parathyroid gland had a significantly higher fluorescence intensity than the other tissues, including the thyroid glands, lymph nodes and fat tissues, and we could identify them during surgery using the fluorescence-guided method. Our method could be applicable for two intraoperative clinical procedures: ex vivo tissue identification of parathyroid tissue and in vivo identification of the location of the parathyroid gland, including ectopic glands. The PDE system may be an easy and highly feasible method to identify the parathyroid gland during surgery.

In situ microbial detection in Mojave Desert soil using native fluorescence.

PubMed

Smith, H D; Duncan, A G; Neary, P L; Lloyd, C R; Anderson, A J; Sims, R C; McKay, C P

2012-03-01

We report on the use of a portable instrument for microbial detection in the Mojave Desert soil and the potential for its use on Mars. The instrument is based on native fluorescence and employs four excitation wavelengths combined with four emission wavelengths. A soil dilution series in which known numbers of Bacillus subtilis spores were added to soil was used to determine the sensitivity of the instrument. We found that the fluorescence of the biological and organic components of the desert soil samples studied can be as strong as the fluorescence of the mineral component of these soils. Using the calibration derived from B. subtilis spores, we estimated that microbial content at our primary sampling site was 10(7) bacteria per gram of soil, a level confirmed by phospholipid fatty acid analysis. At a nearby site, but in a slightly different geological setting, we tested the instrument's ability to map out microbial concentrations in situ. Over a ∼50 m diameter circle, soil microbial concentrations determined with the B. subtilis calibration indicate that the concentrations of microorganisms detected varies from 10(4) to 10(7) cells per gram of soil. We conclude that fluorescence is a promising method for detecting soil microbes in noncontact applications in extreme environments on Earth and may have applications on future missions to Mars.

Fluorescent triplex-forming DNA oligonucleotides labeled with a thiazole orange dimer unit

PubMed Central

Ikeda, Shuji; Yanagisawa, Hiroyuki; Yuki, Mizue; Okamoto, Akimitsu

2013-01-01

Fluorescent probes for the detection of a double-stranded DNA were prepared by labeling a triplex-forming DNA oligonucleotide with a thiazole orange (TO) dimer unit. They belong to ECHO (exciton-controlled hybridization-sensitive fluorescent oligonucleotide) probes which we have previously reported. The excitonic interaction between the two TO molecules was expected to effectively suppress the background fluorescence of the probes. The applicability of the ECHO probes for the detection of double-stranded DNA was confirmed by examining the thermal stability and photophysical and kinetic properties of the DNA triplexes formed by the ECHO probes. PMID:23445822

An AIEE fluorescent supramolecular cross-linked polymer network based on pillar[5]arene host-guest recognition: construction and application in explosive detection.

PubMed

Shao, Li; Sun, Jifu; Hua, Bin; Huang, Feihe

2018-05-08

Here a novel fluorescent supramolecular cross-linked polymer network with aggregation induced enhanced emission (AIEE) properties was constructed via pillar[5]arene-based host-guest recognition. Furthermore, the supramolecular polymer network can be used for explosive detection in both solution and thin films.

Carbon dots for fluorescent detection of α-glucosidase activity using enzyme activated inner filter effect and its application to anti-diabetic drug discovery.

PubMed

Kong, Weiheng; Wu, Di; Xia, Lian; Chen, Xuefeng; Li, Guoliang; Qiu, Nannan; Chen, Guang; Sun, Zhiwei; You, Jinmao; Wu, Yongning

2017-06-22

Recently, α-glucosidase inhibitor has been widely used in clinic for diabetic therapy. In the present study, a facile and sensitive fluorescent assay based on enzyme activated inner filter effect (IFE) on nitrogen-doped carbon dots (CDs) was first developed for the detection of α-glucosidase. The N-doped CDs with green emission were prepared by a one-step hydrothermal synthesis and gave the fluorescence quantum yield of 30%, which were used as the signal output. Through α-glucosidase catalysis, 4-nitrophenol was released from 4-nitrophenyl-α-d-glucopyranoside (NGP). Interestingly, the absorption of 4-nitrophenol and the excitation of CDs were completely overlapping. Due to its great molar absorptivity, 4-nitrophenol was capable of acting as a powerful absorber to affect the fluorescent signal of CDs (i.e. IFE). By converting the absorption signals into fluorescence signals, the facile fluorescence assay strategy could be realized for α-glucosidase activity sensing, which effectively avoided the complex modification of the surface of CDs or construction of the nanoprobes. The established IFE-based sensing platform offered a low detection limit of 0.01 U/mL (S/N = 3). This proposed sensing approach has also been expanded to the inhibitor screening and showed excellent applicability. As a typical α-glucosidase inhibitor, acarbose was investigated with a low detection limit of 10 -8  M. This developed method enjoyed many merits including simplicity, lost cost, high sensitivity, good reproducibility and excellent selectivity, which also provided a new insight on the application of CDs to develop the facile and sensitive biosensor. Copyright © 2017 Elsevier B.V. All rights reserved.

The design and application of fluorophore–gold nanoparticle activatable probes

PubMed Central

Swierczewska, Magdalena; Lee, Seulki; Chen, Xiaoyuan

2013-01-01

Fluorescence-based assays and detection techniques are among the most highly sensitive and popular biological tests for researchers. To match the needs of research and the clinic, detection limits and specificities need to improve, however. One mechanism is to decrease non-specific background signals, which is most efficiently done by increasing fluorescence quenching abilities. Reports in the literature of theoretical and experimental work have shown that metallic gold surfaces and nanoparticles are ultra-efficient fluorescence quenchers. Based on these findings, subsequent reports have described gold nanoparticle fluorescence-based activatable probes that were designed to increase fluorescence intensity based on a range of stimuli. In this way, these probes can detect and signify assorted biomarkers and changes in environmental conditions. In this review, we explore the various factors and theoretical models that affect gold nanoparticle fluorescence quenching, explore current uses of activatable probes, and propose an engineering approach for future development of fluorescence based gold nanoparticle activatable probes. PMID:21380462

Double-cladding-fiber-based detection system for intravascular mapping of fluorescent molecular probes

NASA Astrophysics Data System (ADS)

Razansky, R. Nika; Rozental, Amir; Mueller, Mathias S.; Deliolanis, Nikolaos; Jaffer, Farouc A.; Koch, Alexander W.; Ntziachristos, Vasilis

2011-03-01

Early detection of high-risk coronary atherosclerosis remains an unmet clinical challenge. We have previously demonstrated a near-infrared fluorescence catheter system for two-dimensional intravascular detection of fluorescence molecular probes [1]. In this work we improve the system performance by introducing a novel high resolution sensor. The main challenge of the intravascular sensor is to provide a highly focused spot at an application relevant distance on one hand and a highly efficient collection of emitted light on the other. We suggest employing a double cladding optical fiber (DCF) in combination with focusing optics to provide a sensor with both highly focused excitation light and highly efficient fluorescent light collection. The excitation laser is coupled into the single mode core of DCF and guided through a focusing element and a right angle prism. The resulting side-fired beam exhibits a small spot diameter (50 μm) throughout a distance of up to 2 mm from the sensor. This is the distance of interest for intravascular coronary imaging application, determined by an average human coronary artery diameter. At the blood vessel wall, an activatable fluorescence molecular probe is excited in the diseased lesions. Next light of slightly shifted wavelength emits only in the places of the inflammations, associated with dangerous plaques [2]. The emitted light is collected by the cladding of the DCF, with a large collection angle (NA=0.4). The doublecladding acts as multimodal fiber and guides the collected light to the photo detection elements. The sensor automatically rotates and pulled-back, while each scanned point is mapped according to the amount of detected fluorescent emission. The resulting map of fluorescence activity helps to associate the atherosclerotic plaques with the inflammation process. The presented detection system is a valuable tool in the intravascular plaque detection and can help to differentiate the atherosclerotic plaques based on their biological activity, identify the ones that prone to rupture and therefore require more medical attention.

Green preparation of carbon dots with mangosteen pulp for the selective detection of Fe3+ ions and cell imaging

NASA Astrophysics Data System (ADS)

Yang, Rui; Guo, Xiangfeng; Jia, Lihua; Zhang, Yu; Zhao, Zhenlong; Lonshakov, Fedor

2017-11-01

A simple method was developed in the synthesis of fluorescent carbon dots (referred to as M-CDs), calcined treatment of mangosteen pulp in air, without the assistance of any chemical reagent. The M-CDs possess good-solubility, satisfactory chemical stability and can be applied as the fluorescent temperature probe. More strikingly, the fluorescence of M-CDs can be fleetly and selectively quenched by Fe3+ ions. The phenomenon was used to develop a fluorescent method for facile detection of Fe3+ with a linear range of 0-0.18 mM and a detection limit of 52 nM. Eventually, the M-CDs were applied for cell imaging, demonstrating their potential toward diverse applications.

A rhodol-based fluorescent chemosensor for hydrazine and its application in live cell bioimaging

NASA Astrophysics Data System (ADS)

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.

A unique charge-coupled device/xenon arc lamp based imaging system for the accurate detection and quantitation of multicolour fluorescence.

PubMed

Spibey, C A; Jackson, P; Herick, K

2001-03-01

In recent years the use of fluorescent dyes in biological applications has dramatically increased. The continual improvement in the capabilities of these fluorescent dyes demands increasingly sensitive detection systems that provide accurate quantitation over a wide linear dynamic range. In the field of proteomics, the detection, quantitation and identification of very low abundance proteins are of extreme importance in understanding cellular processes. Therefore, the instrumentation used to acquire an image of such samples, for spot picking and identification by mass spectrometry, must be sensitive enough to be able, not only, to maximise the sensitivity and dynamic range of the staining dyes but, as importantly, adapt to the ever changing portfolio of fluorescent dyes as they become available. Just as the available fluorescent probes are improving and evolving so are the users application requirements. Therefore, the instrumentation chosen must be flexible to address and adapt to those changing needs. As a result, a highly competitive market for the supply and production of such dyes and the instrumentation for their detection and quantitation have emerged. The instrumentation currently available is based on either laser/photomultiplier tube (PMT) scanning or lamp/charge-coupled device (CCD) based mechanisms. This review briefly discusses the advantages and disadvantages of both System types for fluorescence imaging, gives a technical overview of CCD technology and describes in detail a unique xenon/are lamp CCD based instrument, from PerkinElmer Life Sciences. The Wallac-1442 ARTHUR is unique in its ability to scan both large areas at high resolution and give accurate selectable excitation over the whole of the UV/visible range. It operates by filtering both the excitation and emission wavelengths, providing optimal and accurate measurement and quantitation of virtually any available dye and allows excellent spectral resolution between different fluorophores. This flexibility and excitation accuracy is key to multicolour applications and future adaptation of the instrument to address the application requirements and newly emerging dyes.

Application of core-shell-structured CdTe@SiO2 quantum dots synthesized via a facile solution method for improving latent fingerprint detection

NASA Astrophysics Data System (ADS)

Gao, Feng; Han, Jiaxing; Lv, Caifeng; Wang, Qin; Zhang, Jun; Li, Qun; Bao, Liru; Li, Xin

2012-10-01

Fingerprint detection is important in criminal investigation. This paper reports a facile powder brushing technique for improving latent fingerprint detection using core-shell-structured CdTe@SiO2 quantum dots (QDs) as fluorescent labeling marks. Core-shell-structured CdTe@SiO2 QDs are prepared via a simple solution-based approach using NH2NH2·H2O as pH adjustor and stabilizer, and their application for improving latent fingerprint detection is explored. The obtained CdTe@SiO2 QDs show spherical shapes with well-defined core-shell structures encapsulating different amounts of QDs depending on the type of the pH adjustor and stabilizer. Moreover, the fluorescence of CdTe@SiO2 QDs is largely enhanced by surface modification of the SiO2 shell. The CdTe@SiO2 QDs overcome the oxidation problem of pure CdTe QDs in air, thus affording better variability with strong adhesive ability, better resolution, and bright emission colors for practical application in latent fingerprint detection. In comparison with the conventional fluorescence powders, silver powders, and others, the effectiveness of CdTe@SiO2 QD powders for detection of latent fingerprints present on a large variety of object surfaces is greatly improved. The synthesis method for CdTe@SiO2 QDs is simple, cheap, and easy for large-scale production, and thus offers many advantages in the practical application of fingerprint detection.

Poly(thymine)-Templated Copper Nanoparticles as a Fluorescent Indicator for Hydrogen Peroxide and Oxidase-Based Biosensing.

PubMed

Mao, Zhengui; Qing, Zhihe; Qing, Taiping; Xu, Fengzhou; Wen, Li; He, Xiaoxiao; He, Dinggeng; Shi, Hui; Wang, Kemin

2015-07-21

Biomineralized fluorescent metal nanoparticles have attracted considerable interest in many fields by virtue of their excellent properties in synthesis and application. Poly(thymine)-templated fluorescent copper nanoparticles (T-CuNPs) as a promising nanomaterial has been exploited by us recently and displays great potential for signal transducing in biochemical analysis. However, the application of T-CuNPs is rare and still at an early stage. Here, a new fluorescent analytical strategy has been developed for H2O2 and oxidase-based biosensing by exploiting T-CuNPs as an effective signal indicator. The mechanism is mainly based on the poly(thymine) length-dependent formation of T-CuNPs and the probe's oxidative cleavage. In this assay, the probe T40 can effectively template the formation of T-CuNPs by a fast in situ manner in the absence of H2O2, with high fluorescent signal, while the probe is cleaved into short-oligonucleotide fragments by hydroxyl radical (·OH) which is formed from the Fenton reaction in the presence of H2O2, leading to the decline of fluorescence intensity. By taking advantage of H2O2 as a mediator, this strategy is further exploited for oxidase-based biosensing. As the proof-of-concept, glucose in human serum has been chosen as the model system and has been detected, and its practical applicability has been investigated by assay of real clinical blood samples. Results demonstrate that the proposed strategy has not only good detection capability but also eminent detection performance, such as simplicity and low-cost, holding great potential for constructing effective sensors for biochemical and clinical applications.

Highly sensitive optical detection of specific protein in breast cancer cells using microstructured fiber in extremely low sample volume

NASA Astrophysics Data System (ADS)

Padmanabhan, Saraswathi; Shinoj, Vengalathunadakal K.; Murukeshan, Vadakke M.; Padmanabhan, Parasuraman

2010-01-01

A simple optical method using hollow-core photonic crystal fiber for protein detection has been described. In this study, estrogen receptor (ER) from a MCF-7 breast carcinoma cell lysates immobilized inside a hollow-core photonic crystal fiber was detected using anti-ER primary antibody with either Alexa™ Fluor 488 (green fluorescent dye) or 555 (red Fluorescent dye) labeled Goat anti-rabbit IgG as the secondary antibody. The fluorescence fingerprints of the ERα protein were observed under fluorescence microscope, and its optical characteristics were analyzed. The ERα protein detection by this proposed method is based on immuno binding from sample volume as low as 50 nL. This method is expected to offer great potential as a biosensor for medical diagnostics and therapeutics applications.

Multimodal Sensing Strategy Using pH Dependent Fluorescence Switchable System

NASA Astrophysics Data System (ADS)

Muthurasu, A.; Ganesh, V.

2016-12-01

Biomolecules assisted preparation of fluorescent gold nanoparticles (FL-Au NPs) has been reported in this work using glucose oxidase enzyme as both reducing and stabilizing agent and demonstrated their application through multimodal sensing strategy for selective detection of cysteine (Cys). Three different methods namely fluorescence turn OFF-ON strategy, naked eye detection and electrochemical methods are used for Cys detection by employing FL-Au NPs as a common probe. In case of fluorescence turn-OFF method a strong interaction between Au NPs and thiol results in quenching of fluorescence due to replacement of glucose oxidase by Cys at neutral pH. Second mode is based on fluorescence switch-ON strategy where initial fluorescence is significantly quenched by either excess acid or base and further addition of Cys results in appearance of rosy-red and green fluorescence respectively. Visual colour change and fluorescence emission arises due to etching of Au atoms on the surface by thiol leading to formation of Au nanoclusters. Finally, electrochemical sensing of Cys is also carried out using cyclic voltammetry in 0.1 M PBS solution. These findings provide a suitable platform for Cys detection over a wide range of pH and concentration levels and hence the sensitivity can also be tuned accordingly.

Development and application of a fluorescence protein microarray for detecting serum alpha-fetoprotein in patients with hepatocellular carcinoma.

PubMed

Zhang, Aiying; Yin, Chengzeng; Wang, Zhenshun; Zhang, Yonghong; Zhao, Yuanshun; Li, Ang; Sun, Huanqin; Lin, Dongdong; Li, Ning

2016-12-01

Objective To develop a simple, effective, time-saving and low-cost fluorescence protein microarray method for detecting serum alpha-fetoprotein (AFP) in patients with hepatocellular carcinoma (HCC). Method Non-contact piezoelectric print techniques were applied to fluorescence protein microarray to reduce the cost of prey antibody. Serum samples from patients with HCC and healthy control subjects were collected and evaluated for the presence of AFP using a novel fluorescence protein microarray. To validate the fluorescence protein microarray, serum samples were tested for AFP using an enzyme-linked immunosorbent assay (ELISA). Results A total of 110 serum samples from patients with HCC ( n = 65) and healthy control subjects ( n = 45) were analysed. When the AFP cut-off value was set at 20 ng/ml, the fluorescence protein microarray had a sensitivity of 91.67% and a specificity of 93.24% for detecting serum AFP. Serum AFP quantified via fluorescence protein microarray had a similar diagnostic performance compared with ELISA in distinguishing patients with HCC from healthy control subjects (area under receiver operating characteristic curve: 0.906 for fluorescence protein microarray; 0.880 for ELISA). Conclusion A fluorescence protein microarray method was developed for detecting serum AFP in patients with HCC.

Development and application of a fluorescence protein microarray for detecting serum alpha-fetoprotein in patients with hepatocellular carcinoma

PubMed Central

Zhang, Aiying; Yin, Chengzeng; Wang, Zhenshun; Zhang, Yonghong; Zhao, Yuanshun; Li, Ang; Sun, Huanqin; Lin, Dongdong

2016-01-01

Objective To develop a simple, effective, time-saving and low-cost fluorescence protein microarray method for detecting serum alpha-fetoprotein (AFP) in patients with hepatocellular carcinoma (HCC). Method Non-contact piezoelectric print techniques were applied to fluorescence protein microarray to reduce the cost of prey antibody. Serum samples from patients with HCC and healthy control subjects were collected and evaluated for the presence of AFP using a novel fluorescence protein microarray. To validate the fluorescence protein microarray, serum samples were tested for AFP using an enzyme-linked immunosorbent assay (ELISA). Results A total of 110 serum samples from patients with HCC (n = 65) and healthy control subjects (n = 45) were analysed. When the AFP cut-off value was set at 20 ng/ml, the fluorescence protein microarray had a sensitivity of 91.67% and a specificity of 93.24% for detecting serum AFP. Serum AFP quantified via fluorescence protein microarray had a similar diagnostic performance compared with ELISA in distinguishing patients with HCC from healthy control subjects (area under receiver operating characteristic curve: 0.906 for fluorescence protein microarray; 0.880 for ELISA). Conclusion A fluorescence protein microarray method was developed for detecting serum AFP in patients with HCC. PMID:27885040

Preparation and application of new fluorescein-labeled fumonisins B1 in fluorescence polarization analysis technique

USDA-ARS?s Scientific Manuscript database

Objective: To prepare a new fluorescent tracer against common mycotoxins such as fumonisin B1 in order to replace 6-(4,6-Dichlorotriazinyl) aminofluorescein (6-DTAF), an expensive marker, and to develop a technique for quick detection of fumonisin B1 based on the principle of fluorescence polarizati...

Molecular engineering of two-photon fluorescent probes for bioimaging applications

NASA Astrophysics Data System (ADS)

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.

Highly sensitive and selective detection of Pb2+ using a turn-on fluorescent aptamer DNA silver nanoclusters sensor.

PubMed

Zhang, Baozhu; Wei, Chunying

2018-05-15

A novel turn-on fluorescent biosensor has been constructed using C-PS2.M-DNA-templated silver nanoclusters (Ag NCs) with an average diameter of about 1 nm. The proposed approach presents a low-toxic, simple, sensitive, and selective detection for Pb 2+ . The fluorescence intensity of C-PS2.M-DNA-Ag NCs enhances significantly in the presence of Pb 2+ , which is attributed to the special interaction between Pb 2+ and its aptamer DNA PS2.M. Pb 2+ induces the aptamer to form G-quadruplex and makes two darkish DNA/Ag NCs located at the 3' and 5' terminus close, resulting in the fluorescence light-up. Moreover, Pb 2+ can be detected as low as 3.0 nM within a good linear range from 5 to 50 nM (R = 0.9862). Furthermore, the application for detection of Pb 2+ in real water samples further demonstrates the reliability of the sensor. Thus, this sensor system shows a potential application for monitoring Pb 2+ in environmental samples. Copyright © 2018 Elsevier B.V. All rights reserved.

A Reaction-Based Novel Fluorescent Probe for Detection of Hydrogen Sulfide and Its Application in Wine.

PubMed

Wang, Hao; Wang, Jialin; Yang, Shaoxiang; Tian, Hongyu; Sun, Baoguo; Liu, Yongguo

2018-01-01

A new reaction-based fluorescent probe 6-cyanonaphthalen-2-yl-2,4- dinitrobenzenesulfonate (probe 1) was designed and synthesized for detection of hydrogen sulfide (H 2 S). The addition of H 2 S to a solution of probe 1 resulted in a marked fluorescence increased accompanied by a visual color change from colorless to yellow. Importantly, this distinct color response indicates that probe 1 could be used as a visual tool for detection of H 2 S. H 2 S can be detected quantitatively in the concentration range 0 to 25 μM and the detection limit was 30 nM. Moreover, probe 1 was successfully used as a sensor to determine H 2 S levels in red wine and beer. Fluorescent probe 1 could be employed as a visible sensor for H 2 S. Probe 1 could be used to detect H 2 S quantitatively in food simple. © 2017 Institute of Food Technologists®.

Tuning of gold nanoclusters sensing applications with bovine serum albumin and bromelain for detection of Hg2+ ion and lambda-cyhalothrin via fluorescence turn-off and on mechanisms.

PubMed

Bhamore, Jigna R; Jha, Sanjay; Basu, Hirakendu; Singhal, Rakesh Kumar; Murthy, Z V P; Kailasa, Suresh Kumar

2018-04-01

Herein, fluorescent gold nanoclusters (Au NCs) were obtained by one-pot synthetic method using bovine serum albumin (BSA) and bromelain as templates. As-synthesized fluorescent Au NCs were stable and showed bright red fluorescence under UV lamp at 365 nm. The fluorescent Au NCs exhibit the emission intensity at 648 nm when excited at 498 nm. Various techniques were used such as spectroscopy (UV-visible, fluorescence, and Fourier-transform infrared), high-resolution transmission electron microscopy, and dynamic light scattering for the characterization of fluorescent Au NCs. The values of I 0 /I at 648 nm are proportional to the concentrations of Hg 2+ ion in the range from 0.00075 to 5.0 μM and of lambda-cyhalothrin in the range from 0.01 to 10 μM with detection limits of 0.0003 and 0.0075 μM for Hg 2+ ion and lambda-cyhalothrin, respectively. The practical application of the probe was successfully demonstrated by analyzing Hg 2+ ion and lambda-cyhalothrin in water samples. In addition, Au NCs used as probes for imaging of Simplicillium fungal cells. These results indicated that the as-synthesized Au NCs have proven to be promising fluorescent material for the sensing of Hg 2+ ion and lambda-cyhalothrin in environmental and for imaging of microorganism cells in biomedical applications.

Rapid and reliable diagnostic method to detect Zika virus by real-time fluorescence reverse transcription loop-mediated isothermal amplification.

PubMed

Guo, Xu-Guang; Zhou, Yong-Zhuo; Li, Qin; Wang, Wei; Wen, Jin-Zhou; Zheng, Lei; Wang, Qian

2018-04-18

To detect Zika virus more rapidly and accurately, we developed a novel method that utilized a real-time fluorescence reverse transcription loop-mediated isothermal amplification (LAMP) technique. The NS5 gene was amplified by a set of six specific primers that recognized six distinct sequences. The amplification process, including 60 min of thermostatic reaction with Bst DNA polymerase following real-time fluorescence reverse transcriptase using genomic Zika virus standard strain (MR766), was conducted through fluorescent signaling. Among the six pairs of primers that we designate here, NS5 was the most efficient with a high sensitivity of up to 3.3 ng/μl and reproducible specificity on eight pathogen samples that were used as negative controls. The real-time fluorescence reverse transcription LAMP detection process can be completed within 35 min. Our study demonstrated that real-time fluorescence reverse transcription LAMP could be highly beneficial and convenient clinical application to detect Zika virus due to its high specificity and stability.

Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study.

PubMed

Cho, H-M; Ding, H; Ziemer, B P; Molloi, S

2014-12-07

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm(2) in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study

NASA Astrophysics Data System (ADS)

Cho, H.-M.; Ding, H.; Ziemer, BP; Molloi, S.

2014-12-01

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3  ×  3 mm2 in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

Energy response calibration of photon-counting detectors using X-ray fluorescence: a feasibility study

PubMed Central

Cho, H-M; Ding, H; Ziemer, BP; Molloi, S

2014-01-01

Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using X-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for X-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The angular dependence of X-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded X-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of X-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of X-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic X-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the X-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory. PMID:25369288

A Resumable Fluorescent Probe BHN-Fe3O4@SiO2 Hybrid Nanostructure for Fe3+ and its Application in Bioimaging

NASA Astrophysics Data System (ADS)

Zhou, Xi; Wang, Yujiao; Peng, Qi; Liu, Weisheng

2017-12-01

A multifunctional fluorescent probe BHN-Fe3O4@SiO2 nanostructure for Fe3+ was designed and developed. It has a good selective response to Fe3+ with fluorescence quenching and can be recycled using an external magnetic field. With adding EDTA (2.5 × 10-5 M) to the consequent product Fe3+-BHN-Fe3O4@SiO2, Fe3+ can be removed from the complex, and its fluorescence probing ability recovers, which means that this constituted on-off type fluorescence probe could be reversed and reused. At the same time, the probe has been successfully applied for quantitatively detecting Fe3+ in a linear mode with a low limit of detection 1.25 × 10-8 M. Furthermore, the BHN-Fe3O4@SiO2 nanostructure probe is successfully used to detect Fe3+ in living HeLa cells, which shows its great potential in bioimaging detection.

Detection of IgG aggregation by a high throughput method based on extrinsic fluorescence.

PubMed

He, Feng; Phan, Duke H; Hogan, Sabine; Bailey, Robert; Becker, Gerald W; Narhi, Linda O; Razinkov, Vladimir I

2010-06-01

The utility of extrinsic fluorescence as a tool for high throughput detection of monoclonal antibody aggregates was explored. Several IgG molecules were thermally stressed and the high molecular weight species were fractionated using size-exclusion chromatography (SEC). The isolated aggregates and monomers were studied by following the fluorescence of an extrinsic probe, SYPRO Orange. The dye displayed high sensitivity to structurally altered, aggregated IgG structures compared to the native form, which resulted in very low fluorescence in the presence of the dye. An example of the application is presented here to demonstrate the properties of this detection method. The fluorescence assay was shown to correlate with the SEC method in quantifying IgG aggregates. The fluorescent probe method appears to have potential to detect protein particles that could not be analyzed by SEC. This method may become a powerful high throughput tool to detect IgG aggregates in pharmaceutical solutions and to study other protein properties involving aggregation. It can also be used to study the kinetics of antibody particle formation, and perhaps allow identification of the species, which are the early building blocks of protein particles. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

Sensitivity evaluation of rhodamine B hydrazide towards nitric oxide and its application for macrophage cells imaging.

PubMed

Wu, Chi-Ming; Chen, Yen-Hao; Dayananda, Kasala; Shiue, Tsun-Wei; Hung, Chen-Hsiung; Liaw, Wen-Feng; Chen, Po-Yu; Wang, Yun-Ming

2011-12-05

A colorless and non-fluorescent rhodamine derivative, rhodamine B hydrazide (RH), is applied to detect nitric oxide and form fluorescent rhodamine B (RB). The reaction mechanism of RH with NO is proposed in this study. The probe shows good stability over a broad pH range (pH>4). Furthermore, fluorescence intensity of RH displays an excellent linearity to the NO concentration and the detection limit is as low as 20 nM. A 1000-fold fluorescence turn-on from a dark background was observed. Moreover, the selectivity study indicated that the fluorescence intensity increasing in the presence of NO was significantly higher than those of other reactive oxygen/nitrogen species. In exogenously generated NO detection study, clear intracellular red fluorescence was observed in the presence of S-nitroso-N-acetyl-D,L-penicillamine (SNAP, a kind of NO releasing agent). In endogenously generated NO detection study, increasing incubation time of RH with lipopolysaccharied (LPS) pre-treated cells could obtain a highly fluorescent cell image. These cell imaging results demonstrated that RH can efficiently penetrate into Raw 264.7 cells and be used for detection of exogenously and endogenously generated nitric oxide. Copyright © 2011 Elsevier B.V. All rights reserved.

Competition-Mediated Pyrene-Switching Aptasensor: Probing Lysozyme in Human Serum with a Monomer-Excimer Fluorescence Switch

PubMed Central

Huang, Jin; Zhu, Zhi; Bamrungsap, Suwussa; Zhu, Guizhi; You, Mingxu; He, Xiaoxiao; Wang, Kemin; Tan, Weihong

2010-01-01

Lysozyme (Lys) plays crucial roles in the innate immune system, and the detection of Lys in urine and serum has considerable clinical importance. Traditionally, the presence of Lys has been detected by immunoassays; however, these assays are limited by the availability of commercial antibodies and tedious protein modification, and prior sample purification. To address these limitations, we report here the design, synthesis and application of a competition-mediated pyrene-switching aptasensor for selective detection of Lys in buffer and human serum. The detection strategy is based on the attachment of pyrene molecules to both ends of a hairpin DNA strand, which becomes the partially complementary competitor to an anti-Lys aptamer. In the presence of target Lys, the aptamer hybridizes with part of the competitor, which opens the hairpin such that both pyrene molecules are spatially separated. In the presence of target Lys, however, the competitor is displaced from the aptamer by the target, subsequently forming an initial hairpin structure. This brings the two pyrene moieties into close proximity to generate an excimer, which, in turn, results in a shift of fluorescence emission from ca. 400 nm (pyrene monomer) to 495 nm (pyrene excimer). The proposed method for Lys detection showed sensitivity as low as 200 pM and high selectivity in buffer. When measured by steady-state fluorescence spectrum, the detection of Lys in human serum showed a strong fluorescent background, which obscured detection of the excimer signal. However, time-resolved emission measurement (TREM) supported the potential of the method in complex environments with background fluorescence by demonstrating the temporal separation of probe fluorescence emission decay from the intense background signal. We have also demonstrated that the same strategy can be applied to the detection of small biomolecules such as adenosine triphosphate (ATP), sowing the generality of our approach. Therefore, the competition-mediated pyrene-switching aptasensor is promising to have potential for clinical and forensic applications. PMID:21080638

Highly selective fluorescence turn-on sensor for fluoride detection.

PubMed

Sui, Binglin; Kim, Bosung; Zhang, Yuanwei; Frazer, Andrew; Belfield, Kevin D

2013-04-24

Through click chemistry, triazole and triazolium groups have been explored to recognize anions through C-H···A(-) hydrogen-bonding complexion. Herein, we demonstrate evidence of fluoride-induced deprotonation of a C-H bond and its application in fluoride detection. The combination of fluorene and triazolium units produced a highly selective fluorescence turn-on prototype sensor for fluoride. The interactions between the C-H bond and F(-) were studied by fluorescence spectroscopy and (1)H NMR titrations. Test papers were prepared to detect fluoride in aqueous media at concentrations down to 1.9 ppm, important for estimating whether the fluoride concentration in drinking water is at a safe level.

A graphene oxide-based fluorescent aptasensor for the turn-on detection of epithelial tumor marker mucin 1.

PubMed

He, Yue; Lin, Yi; Tang, Hongwu; Pang, Daiwen

2012-03-21

Mucin 1 (MUC1) which presents in epithelial malignancies, is a well-known tumor biomarker. In this paper, a highly sensitive and selective fluorescent aptasensor for Mucin 1 (MUC1) detection is constructed, utilizing graphene oxide (GO) as a quencher which can quench the fluorescence of single-stranded dye-labeled MUC1 specific aptamer. In the absence of MUC1, the adsorption of the dye-labeled aptamer on GO brings the dyes in close proximity to the GO surface resulting in high efficiency quenching of dye fluorescence. Therefore, the fluorescence of the designed aptasensor is completely quenched by GO, and the system shows very low background fluorescence. Conversely, and very importantly, upon the adding of MUC1, the quenched fluorescence is recovered significantly, and MUC1 can be detected in a wide range of 0.04-10 μM with a detection limit of 28 nM and good selectivity. Moreover, the results have also been verified for real sample application by testing 2% serum containing buffer solution spiked with a series of concentrations of MUC1. This journal is © The Royal Society of Chemistry 2012

A simple turn on fluorescent sensor for the selective detection of thiamine using coconut water derived luminescent carbon dots.

PubMed

Purbia, Rahul; Paria, Santanu

2016-05-15

In this study microwave-assisted hydrothermal method was used to prepare highly luminescent carbon dots (1-6 nm size) within a minute from tender coconut (Cocos nucifera) water. The synthesized carbon dots (C-dots) exhibit emission of blue and green lights while excited at 390 and 450 nm wavelengths, respectively. As an application, these C-dots were tested for a simple "turn on" fluorescent sensor for rapid detection of thiamine (vitamin B1). The detection of thiamine in human body is very important to prevent various diseases such as beriberi, neurological disorders, optic neuropathy, etc. The fluorescence emission intensity of C-dots quenches after addition of Cu(2+) ion and then again increases selectively (turn on) after the addition of thiamine. The fluorescence emission intensity enhancement of Cu(2+) ion modified C-dots in the presence of thiamine exhibits a linear relationship within the thiamine concentration range of 10-50 μM. The limit of detection was found to be 280 nM from this study. The selectivity of the detection was also tested in the presence of different organic molecules and inorganic ions (Ca(2+), Mg(2+), Na(+), K(+), Cl(-), SO4(2-), and NO3(-)) which are present in blood serum and urine and found to be almost no interference in the detection. Finally, to see the applicability in real samples a commercial vitamin capsule was tested and found less than 3% error in the detected concentration. The C-dots were also used for bioimaging of fungus and the results show they are also suitable for this application too. Copyright © 2015 Elsevier B.V. All rights reserved.

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

PubMed

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.

Label-Free Platform for MicroRNA Detection Based on the Fluorescence Quenching of Positively Charged Gold Nanoparticles to Silver Nanoclusters.

PubMed

Miao, Xiangmin; Cheng, Zhiyuan; Ma, Haiyan; Li, Zongbing; Xue, Ning; Wang, Po

2018-01-16

A novel strategy was developed for microRNA-155 (miRNA-155) detection based on the fluorescence quenching of positively charged gold nanoparticles [(+)AuNPs] to Ag nanoclusters (AgNCs). In the designed system, DNA-stabilized Ag nanoclusters (DNA/AgNCs) were introduced as fluorescent probes, and DNA-RNA heteroduplexes were formed upon the addition of target miRNA-155. Meanwhile, the (+)AuNPs could be electrostatically adsorbed on the negatively charged single-stranded DNA (ssDNA) or DNA-RNA heteroduplexes to quench the fluorescence signal. In the presence of duplex-specific nuclease (DSN), DNA-RNA heteroduplexes became a substrate for the enzymatic hydrolysis of the DNA strand to yield a fluorescence signal due to the diffusion of AgNCs away from (+)AuNPs. Under the optimal conditions, (+)AuNPs displayed very high quenching efficiency to AgNCs, which paved the way for ultrasensitive detection with a low detection limit of 33.4 fM. In particular, the present strategy demonstrated excellent specificity and selectivity toward the detection of target miRNA against control miRNAs, including mutated miRNA-155, miRNA-21, miRNA-141, let-7a, and miRNA-182. Moreover, the practical application value of the system was confirmed by the evaluation of the expression levels of miRNA-155 in clinical serum samples with satisfactory results, suggesting that the proposed sensing platform is promising for applications in disease diagnosis as well as the fundamental research of biochemistry.

Blending DNA binding dyes to improve detection in real-time PCR.

PubMed

Jansson, Linda; Koliana, Marianne; Sidstedt, Maja; Hedman, Johannes

2017-03-01

The success of real-time PCR (qPCR) analysis is partly limited by the presence of inhibitory compounds in the nucleic acid samples. For example, humic acid (HA) from soil and aqueous sediment interferes with amplification and also quenches the fluorescence of double-stranded (ds) DNA binding dyes, thus hindering amplicon detection. We aimed to counteract the HA fluorescence quenching effect by blending complementary dsDNA binding dyes, thereby elevating the dye saturation levels and increasing the fluorescence signals. A blend of the four dyes EvaGreen, ResoLight, SYBR Green and SYTO9 gave significantly higher fluorescence intensities in the presence and absence of HA, compared with the dyes applied separately and two-dye blends. We propose blending of dyes as a generally applicable means for elevating qPCR fluorescence signals and thus enabling detection in the presence of quenching substances.

Automatic enhancement of skin fluorescence localization due to refractive index matching

NASA Astrophysics Data System (ADS)

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

2004-07-01

Fluorescence diagnostic techniques are notable amongst many other optical methods, as they offer high sensitivity and non-invasive measurements of tissue properties. However, a combination of multiple scattering and physical heterogeneity of biological tissues hampers the interpretation of the fluorescence measurements. The analyses of the spatial distribution of endogenous and exogenous fluorophores excitations within tissues and their contribution to the detected signal localization are essential for many applications. We have developed a novel Monte Carlo technique that gives a graphical perception of how the excitation and fluorescence detected signal are localized in tissues. Our model takes into account spatial distribution of fluorophores and their quantum yields. We demonstrate that matching of the refractive indices of ambient medium and topical skin layer improves spatial localization of the detected fluorescence signal within the tissue. This result is consistent with the recent conclusion that administering biocompatible agents results in higher image contrast.

Qualitative and Quantitative Analysis of Histone Deacetylases in Kidney Tissue Sections.

PubMed

Ververis, Katherine; Marzully, Selly; Samuel, Chrishan S; Hewitson, Tim D; Karagiannis, Tom C

2016-01-01

Fluorescent microscope imaging technologies are increasing in their applications and are being used on a wide scale. However methods used to quantify the level of fluorescence intensity are often not utilized-perhaps given the result may be immediately seen, quantification of the data may not seem necessary. However there are a number of reasons given to quantify fluorescent images including the importance of removing potential bias in the data upon observation as well as quantification of large numbers of images gives statistical power to detect subtle changes in experiments. In addition discreet localization of a protein could be detected without selection bias that may not be detectable by eye. Such data will be deemed useful when detecting the levels of HDAC enzymes within cells in order to develop more effective HDAC inhibitor compounds for use against multiple diseased states. Hence, we discuss a methodology devised to analyze fluorescent images using Image J to detect the mean fluorescence intensity of the 11 metal-dependent HDAC enzymes using murine kidney tissue sections as an example.

Novel and remarkable enhanced-fluorescence system based on gold nanoclusters for detection of tetracycline.

PubMed

Yang, Xiaoming; Zhu, Shanshan; Dou, Yao; Zhuo, Yan; Luo, Yawen; Feng, Yuanjiao

2014-05-01

Tetracycline and Eu(3+), while coexisting, usually appear as a complex by chelating. This complex shows low fluorescence intensity, leading to its limitation of analytical goals. Gold nanoclusters (AuNCs), emerging as novel nano-material, are attracting increasing attentions in multiple fields. Herein, gold nanoclusters first function as a fluorescence-enhanced reagent rather than a conventional fluorescent-probe, and a dramatic enhanced-fluorescence system was built based on Eu(3+)-Tetracycline complex (EuTC) by introducing gold nanoclusters. Simultaneously, three types of gold nanoclusters were employed for exploring various conditions likely affecting the system, which demonstrate that no other gold nanoclusters than DNA-templated gold nanoclusters enormously caused fluorescence-enhancement of EuTC. Moreover, this enhanced-fluorescence system permitted available detection of tetracycline (TC) in a linear range of 0.01-5 μM, with a detection limit of 4 nM at a signal-to-noise ratio of 3. Significantly, the practicality of this method for detection of TC in human urine and milk samples was validated, demonstrating its advantages of simplicity, sensitivity and low cost. Interestingly, this system described here is probably promising for kinds of applications based on its dramatically enhanced-fluorescence. © 2013 Published by Elsevier B.V.

New Monte Carlo model of cylindrical diffusing fibers illustrates axially heterogeneous fluorescence detection: simulation and experimental validation

PubMed Central

Baran, Timothy M.; Foster, Thomas H.

2011-01-01

We present a new Monte Carlo model of cylindrical diffusing fibers that is implemented with a graphics processing unit. Unlike previously published models that approximate the diffuser as a linear array of point sources, this model is based on the construction of these fibers. This allows for accurate determination of fluence distributions and modeling of fluorescence generation and collection. We demonstrate that our model generates fluence profiles similar to a linear array of point sources, but reveals axially heterogeneous fluorescence detection. With axially homogeneous excitation fluence, approximately 90% of detected fluorescence is collected by the proximal third of the diffuser for μs'/μa = 8 in the tissue and 70 to 88% is collected in this region for μs'/μa = 80. Increased fluorescence detection by the distal end of the diffuser relative to the center section is also demonstrated. Validation of these results was performed by creating phantoms consisting of layered fluorescent regions. Diffusers were inserted into these layered phantoms and fluorescence spectra were collected. Fits to these spectra show quantitative agreement between simulated fluorescence collection sensitivities and experimental results. These results will be applicable to the use of diffusers as detectors for dosimetry in interstitial photodynamic therapy. PMID:21895311

Fluorescence quencher improves SCANSYSTEM for rapid bacterial detection.

PubMed

Schmidt, M; Hourfar, M K; Wahl, A; Nicol, S-B; Montag, T; Roth, W K; Seifried, E

2006-05-01

The optimized scansystem could detect contaminated platelet products within 24 h. However, the system's sensitivity was reduced by a high fluorescence background even in sterile samples, which led to the necessity of a well-trained staff for confirmation of microscope results. A new protocol of the optimized scansystem with the addition of a fluorescence quencher was evaluated. Pool platelet concentrates contaminated with five transfusion-relevant bacterial strains were tested in a blind study. In conjunction with new analysis software, the new quenching dye was able to reduce significantly unspecific background fluorescence. Sensitivity was best for Bacillus cereus and Escherichia coli (3 CFU/ml). The application of a fluorescence quencher enables automated discrimination of positive and negative test results in 60% of all analysed samples.

Green synthesis of carbon dots from pork and application as nanosensors for uric acid detection

NASA Astrophysics Data System (ADS)

Zhao, Chunxi; Jiao, Yang; Hu, Feng; Yang, Yaling

2018-02-01

In this work, a green, simple, economical method was developed in the synthesis of fluorescent carbon dots using pork as carbon source. The as-prepared carbon dots exhibit exceptional advantages including high fluorescent quantum yield (17.3%) and satisfactory chemical stability. The fluorescence of carbon dots based nanosensor can be selectively and efficiently quenched by uric acid. This phenomenon was used to develop a fluorescent method for facile detection of uric acid within a linear range of 0.1-100 μM and 100-500 μM, with a detection limit of 0.05 μM (S/N = 3). Finally, the proposed method was successfully applied in the determination of uric acid in human serum and urine samples with satisfactory recoveries, which suggested that the new nanosensors have great prospect toward the detection of uric acid in human fluids.

Designed Strategies for Fluorescence-Based Biosensors for the Detection of Mycotoxins

PubMed Central

Sharma, Atul; Khan, Reem; Catanante, Gaelle; Sherazi, Tauqir A.; Bhand, Sunil; Hayat, Akhtar; Marty, Jean Louis

2018-01-01

Small molecule toxins such as mycotoxins with low molecular weight are the most widely studied biological toxins. These biological toxins are responsible for food poisoning and have the potential to be used as biological warfare agents at the toxic dose. Due to the poisonous nature of mycotoxins, effective analysis techniques for quantifying their toxicity are indispensable. In this context, biosensors have been emerged as a powerful tool to monitors toxins at extremely low level. Recently, biosensors based on fluorescence detection have attained special interest with the incorporation of nanomaterials. This review paper will focus on the development of fluorescence-based biosensors for mycotoxin detection, with particular emphasis on their design as well as properties such as sensitivity and specificity. A number of these fluorescent biosensors have shown promising results in food samples for the detection of mycotoxins, suggesting their future potential for food applications. PMID:29751687

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3 + and its practical application

NASA Astrophysics Data System (ADS)

Zhang, Shanshan; Sun, Tao; Xiao, Dejun; Yuan, Fang; Li, Tianduo; Wang, Enhua; Liu, Haixia; Niu, Qingfen

2018-01-01

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe3 + detection was designed and synthesized. In presence of Fe3 +, sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe3 + complex was found as 2.4 × 104 with the lower detection limit of 14.3 nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1H NMR spectra. Sensor L for Fe3 + detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe3 + ions in practical water samples with good recovery.

Designed Strategies for Fluorescence-Based Biosensors for the Detection of Mycotoxins.

PubMed

Sharma, Atul; Khan, Reem; Catanante, Gaelle; Sherazi, Tauqir A; Bhand, Sunil; Hayat, Akhtar; Marty, Jean Louis

2018-05-11

Small molecule toxins such as mycotoxins with low molecular weight are the most widely studied biological toxins. These biological toxins are responsible for food poisoning and have the potential to be used as biological warfare agents at the toxic dose. Due to the poisonous nature of mycotoxins, effective analysis techniques for quantifying their toxicity are indispensable. In this context, biosensors have been emerged as a powerful tool to monitors toxins at extremely low level. Recently, biosensors based on fluorescence detection have attained special interest with the incorporation of nanomaterials. This review paper will focus on the development of fluorescence-based biosensors for mycotoxin detection, with particular emphasis on their design as well as properties such as sensitivity and specificity. A number of these fluorescent biosensors have shown promising results in food samples for the detection of mycotoxins, suggesting their future potential for food applications.

An aircraft compatible laser induced fluorescence system - In situ and remote measurements of trace gases

NASA Technical Reports Server (NTRS)

Davis, D. D.; Philen, D.

1978-01-01

The laser-induced fluorescence technique for obtaining direct measurements of atmospheric OH and other gases is described. A narrow-band UV laser is tuned to one or more of the electronic absorption bands of a specified molecule so as to cause fluorescence from a bonding excited electronic state. The monitored wavelength is longer than the laser wavelength. Equipment, specifics for OH detection, data processing, and interference are discussed, and application of the technique to the detection of NO, SO2, and CH2O is considered.

Two-photon excitation in chip electrophoresis enabling label-free fluorescence detection in non-UV transparent full-body polymer chips.

PubMed

Geissler, David; Belder, Detlev

2015-12-01

One of the most commonly employed detection methods in microfluidic research is fluorescence detection, due to its ease of integration and excellent sensitivity. Many analytes though do not show luminescence when excited in the visible light spectrum, require suitable dyes. Deep-ultraviolet (UV) excitation (<300 nm) allows label-free detection of a broader range of analytes but also mandates the use of expensive fused silica glass, which is transparent to UV light. Herein, we report the first application of label-free deep UV fluorescence detection in non-UV transparent full-body polymer microfluidic devices. This was achieved by means of two-photon excitation in the visible range (λex = 532 nm). Issues associated with the low optical transmittance of plastics in the UV range were successfully circumvented in this way. The technique was investigated by application to microchip electrophoresis of small aromatic compounds. Various polymers, such as poly(methyl methacrylate), cyclic olefin polymer, and copolymer as well as poly(dimethylsiloxane) were investigated and compared with respect to achievable LOD and ruggedness against photodamage. To demonstrate the applicability of the technique, the method was also applied to the determination of serotonin and tryptamine in fruit samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dendrochemical patterns of calcium, zinc, and potassium related to internal factors detected by energy dispersive X-ray fluorescence (EDXRF)

Treesearch

Kevin T. Smith; Jean Christophe Balouet; Walter C. Shortle; Michel Chalot; François Beaujard; Hakan Grudd; Don A. Vroblesky; Joel G. Burken

2014-01-01

Energy dispersive X-ray fluorescence (EDXRF) provides highly sensitive and precise spatial resolution of cation content in individual annual growth rings in trees. The sensitivity and precision have prompted successful applications to forensic dendrochemistry and the timing of environmental releases of contaminants. These applications have highlighted the need to...

Confocal fluorescence techniques in industrial application

NASA Astrophysics Data System (ADS)

Eggeling, Christian; Gall, Karsten; Palo, Kaupo; Kask, Peet; Brand, Leif

2003-06-01

The FCS+plus family of evaluation tools for confocal fluorescence spectroscopy, which was developed during recent years, offers a comprehensive view to a series of fluorescence properties. Originating in fluorescence correlation spectroscopy (FCS) and using similar experimental equipment, a system of signal processing methods such as fluorescence intensity distribution analysis (FIDA) was created to analyze in detail the fluctuation behavior of fluorescent particles within a small area of detection. Giving simultaneous access to molecular parameters like concentration, translational and rotational diffusion, molecular brightness, and multicolor coincidence, this portfolio was enhanced by more traditional techniques of fluorescence lifetime as well as time-resolved anisotropy determination. The cornerstones of the FCS+plus methodology will be shortly described. The inhibition of a phosphatase enzyme activity gives a comprehensive industrial application that demonstrates FCS+plus' versatility and its potential for pharmaceutical drug discovery.

Presence of Fluorescent Carbon Nanoparticles in Baked Lamb: Their Properties and Potential Application for Sensors.

PubMed

Wang, Haitao; Xie, Yisha; Liu, Shan; Cong, Shuang; Song, Yukun; Xu, Xianbing; Tan, Mingqian

2017-08-30

The presence of nanoparticles in food has drawn much attention in recent years. Fluorescent carbon nanoparticles are a new class of nanostructures; however, the distribution and physicochemical properties of such nanoparticles in food remain unclear. Herein, the presence of fluorescent carbon nanoparticles in baked lamb was confirmed, and their physicochemical properties were investigated. The fluorescent carbon nanoparticles from baked lamb emit strong blue fluorescence under ultraviolet light with a 10% fluorescent quantum yield. The nanoparticles are roughly spherical in appearance with a diameter of around 2.0 nm. Hydroxyl, amino, and carboxyl groups exist on the surface of nanoparticles. In addition, the nanoparticles could serve as a fluorescence sensor for glucose detection through an oxidation-reduction reaction. This work is the first report on fluorescent carbon nanoparticles present in baked lamb, which provides valuable insight into the physicochemical properties of such nanoparticles and their potential application in sensors.

Fabrication of peptide stabilized fluorescent gold nanocluster/graphene oxide nanocomplex and its application in turn-on detection of metalloproteinase-9.

PubMed

Nguyen, Phuong-Diem; Cong, Vu Thanh; Baek, Changyoon; Min, Junhong

2017-03-15

This study introduces the double-ligands stabilizing gold nanoclusters and the fabrication of gold nanocluster/graphene nanocomplex as a "turn-on" fluorescent probe for the detection of cancer-related enzyme matrix metalloproteinase-9. A facile, one-step approach was developed for the synthesis of fluorescent gold nanoclusters using peptides and mercaptoundecanoic acid as co-templating ligands. The peptide was designed to possess a metalloproteinase-9 cleavage site and to act not only as a stabilizer but also as a targeting ligand for the enzyme detection. The prepared gold nanoclusters show an intense red fluorescence with a broad adsorption spectrum. In the presence of the enzyme, due to the excellent quenching properties and the negligible background of graphene oxide, the developed peptide-gold nanocluster/graphene nanocomplex yielded an intense "turn-on" fluorescent response, which strongly correlated with the enzyme concentration. The limit of detection of the nanocomplex was 0.15nM. The sensor was successfully applied for "turn-on" detection of metalloproteinase-9 secreted from human breast adenocarcinoma MCF-7 cells with high sensitivity, selectivity, significant improvement in terms of detection time and simplicity. Copyright © 2015 Elsevier B.V. All rights reserved.

Spatially selective photonic crystal enhanced fluorescence and application to background reduction for biomolecule detection assays

PubMed Central

Chaudhery, Vikram; Huang, Cheng-Sheng; Pokhriyal, Anusha; Polans, James; Cunningham, Brian T.

2011-01-01

By combining photonic crystal label-free biosensor imaging with photonic crystal enhanced fluorescence, it is possible to selectively enhance the fluorescence emission from regions of the PC surface based upon the density of immobilized capture molecules. A label-free image of the capture molecules enables determination of optimal coupling conditions of the laser used for fluorescence imaging of the photonic crystal surface on a pixel-by-pixel basis, allowing maximization of fluorescence enhancement factor from regions incorporating a biomolecule capture spot and minimization of background autofluorescence from areas between capture spots. This capability significantly improves the contrast of enhanced fluorescent images, and when applied to an antibody protein microarray, provides a substantial advantage over conventional fluorescence microscopy. Using the new approach, we demonstrate detection limits as low as 0.97 pg/ml for a representative protein biomarker in buffer. PMID:22109210

Contact-lens type of micromachined hydrogenated amorphous Si fluorescence detector coupled with microfluidic electrophoresis devices

NASA Astrophysics Data System (ADS)

Kamei, Toshihiro; Wada, Takehito

2006-09-01

A 5.8-μm-thick SiO2/Ta2O5 multilayer optical interference filter was monolithically integrated and micromachined on a hydrogenated amorphous Si (a-Si :H) pin photodiode to form a fluorescence detector. A microfluidic electrophoresis device was mounted on a detection platform comprising a fluorescence-collecting half-ball lens and the micromachined fluorescence detector. The central aperture of the fluorescence detector allows semiconductor laser light to pass up through the detector and to irradiate an electrophoretic separation channel. The limit of detection is as low as 7nM of the fluorescein solution, and high-speed DNA fragment sizing can be achieved with high separation efficiency. The micromachined a-Si :H fluorescence detector exhibits high sensitivity for practical fluorescent labeling dyes as well as integration flexibility on various substances, making it ideal for application to portable microfluidic bioanalysis devices.

Spatially selective photonic crystal enhanced fluorescence and application to background reduction for biomolecule detection assays.

PubMed

Chaudhery, Vikram; Huang, Cheng-Sheng; Pokhriyal, Anusha; Polans, James; Cunningham, Brian T

2011-11-07

By combining photonic crystal label-free biosensor imaging with photonic crystal enhanced fluorescence, it is possible to selectively enhance the fluorescence emission from regions of the PC surface based upon the density of immobilized capture molecules. A label-free image of the capture molecules enables determination of optimal coupling conditions of the laser used for fluorescence imaging of the photonic crystal surface on a pixel-by-pixel basis, allowing maximization of fluorescence enhancement factor from regions incorporating a biomolecule capture spot and minimization of background autofluorescence from areas between capture spots. This capability significantly improves the contrast of enhanced fluorescent images, and when applied to an antibody protein microarray, provides a substantial advantage over conventional fluorescence microscopy. Using the new approach, we demonstrate detection limits as low as 0.97 pg/ml for a representative protein biomarker in buffer.

[Analysis of EML4-ALK gene fusion mutation in patients 
with non-small cell lung cancer].

PubMed

Wang, Xuzhou; Chen, Weisheng; Yu, Yinghao

2015-02-01

Non-small cell lung cancer (NSCLC) is the main type of lung cancer, and the related locus mutation detection research has become a hot direction of molecular targeted therapy, studying on gene mutation status of echinodem microtubule associated protein like 4-Anaplastic lymphoma kinase (EML4-ALK) and epidermal growth factor receptor (EGFR), detecting the sensitivity of EML4-ALK gene fusion and gene mutation of EGFR. EML4-ALK gene fusion in 85 cases of paraffin embedded tumor tissue and adjacent lung tissue was detected with the application of immunohistochemistry (IHC), Scorpions amplification refractory mutation system (Scorpions ARMS) fluorescence quantitative PCR and fluorescence in situ hybridization (FISH) technology, and EGFR gene in 18, 19, 20 and 21 exon mutation status was detected with the application of ARMS method. In 115 cases of NSCLC, IHC showed 32 cases with ALK (D5F3) expression, the expression rate was 27.8%; ARMS showed 27 cases with EML4-ALK fusion gene mutation, the mutation detection rate was 23.5%; 53 cases were detected with EGFR mutation, the mutation rate was 46%. While FISH showed 23 cases with EML4-ALK fusion gene mutation, the detection rate was 20%, slightly lower than the ARMS detection results, suggesting that ARMS more sensitive. The application of IHC, ARMS fluorescence quantitative PCR and FISH technology can make a rapid and accurate evaluation of EML4-ALK gene fusion.

Label-free fluorescent aptasensor for potassium ion using structure-switching aptamers and berberine

NASA Astrophysics Data System (ADS)

Guo, Yanqing; Chen, Yanxia; Wei, Yanli; Li, Huanhuan; Dong, Chuan

2015-02-01

A simple, rapid and label-free fluorescent aptasensor was fabricated for the detection of potassium ion (K+ ion) in aqueous solution using K+ ion-stabilized single stranded DNA (ssDNA) with G-rich sequence as the recognition element and a fluorescent dye, berberine, as the fluorescence probe. In the presence of K+ ion, the G-rich ssDNA is promoted to form the aptamer-target complex with a G-quadruplex conformation, and berberine binding to the G-quadruplex structure results in the enhancement of its fluorescence. The fluorescence intensity of the sensing system displayed a calibration response for K+ ion in the range of 0-1600 μM with a detection limit of 31 nM (S/N = 3) and a relative standard deviation (RSD) of 0.45%. This label-free fluorescence aptasensor is conveniently and effectively applicable for analysis of K+ ion in blood serum samples with the recovery range of 81.7-105.3%. The assay for detection of potassium ion is easy, economical, robust, and stable in rough conditions.

A G-quadruplex based fluorescent oligonucleotide turn-on probe towards iodides detection in real samples.

PubMed

Li, Qian; Li, Shuaihua; Chen, Xiu; Bian, Liujiao

2017-09-01

A basket-type G-quadruplex (GQ) fluorescent oligonucleotide (OND) probe is designed to detect iodides dependent on thymine-Hg(II)-thymine (T-Hg(II)-T) base pairs and the intrinsic fluorescence quenching capacity of GQ. In the presence of Hg(II) ions (Hg 2+ ), the two hexachloro-fluorescein-labeled ONDs form a hairpin structure and the fluorophores are dragged close to the GQ, leading to fluorescence quenching of the probe due to photoinduced electron transfer. Upon addition of iodide anions, Hg 2+ are extracted from T-Hg(II)-T complexes which attributes to the stronger binding with iodide anions, resulting in the fluorescence recovery. Through performing the fluorescence quenching and recovery processes, this probe developed a fluorescence turn-on sensor for iodide anions determination over a linear range of 20-200nmol/L with a limit of detection of 5nmol/L. The practical use of the turn-on technology was demonstrated by its application in determination of iodides in water, food, pharmaceutical products and biological samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Status of miniature integrated UV resonance fluorescence and Raman sensors for detection and identification of biochemical warfare agents

NASA Astrophysics Data System (ADS)

Hug, William F.; Bhartia, Rohit; Taspin, Alexandre; Lane, Arthur; Conrad, Pamela; Sijapati, Kripa; Reid, Ray D.

2005-11-01

Laser induced native fluorescence (LINF) is the most sensitive method of detection of biological material including microorganisms, virus', and cellular residues. LINF is also a sensitive method of detection for many non-biological materials as well. The specificity with which these materials can be classified depends on the excitation wavelength and the number and location of observation wavelengths. Higher levels of specificity can be obtained using Raman spectroscopy but a much lower levels of sensitivity. Raman spectroscopy has traditionally been employed in the IR to avoid fluorescence. Fluorescence rarely occurs at wavelength below about 270nm. Therefore, when excitation occurs at a wavelength below 250nm, no fluorescence background occurs within the Raman fingerprint region for biological materials. When excitation occurs within electronic resonance bands of the biological target materials, Raman signal enhancement over one million typically occurs. Raman sensitivity within several hundred times fluorescence are possible in the deep UV where most biological materials have strong absorption. Since the Raman and fluorescence emissions occur at different wavelength, both spectra can be observed simultaneously, thereby providing a sensor with unique sensitivity and specificity capability. We will present data on our integrated, deep ultraviolet, LINF/Raman instruments that are being developed for several applications including life detection on Mars as well as biochemical warfare agents on Earth. We will demonstrate the ability to discriminate organic materials based on LINF alone. Together with UV resonance Raman, higher levels of specificity will be demonstrated. In addition, these instruments are being developed as on-line chemical sensors for industrial and municipal waste streams and product quality applications.

Multifunctional ferritin cage nanostructures for fluorescence and MR imaging of tumor cells

NASA Astrophysics Data System (ADS)

Li, Ke; Zhang, Zhi-Ping; Luo, Ming; Yu, Xiang; Han, Yu; Wei, Hong-Ping; Cui, Zong-Qiang; Zhang, Xian-En

2011-12-01

Bionanoparticles and nanostructures have attracted increasing interest as versatile and promising tools in many applications including biosensing and bioimaging. In this study, to image and detect tumor cells, ferritin cage-based multifunctional hybrid nanostructures were constructed that: (i) displayed both the green fluorescent protein and an Arg-Gly-Asp peptide on the exterior surface of the ferritin cages; and (ii) incorporated ferrimagnetic iron oxide nanoparticles into the ferritin interior cavity. The overall architecture of ferritin cages did not change after being integrated with fusion proteins and ferrimagnetic iron oxide nanoparticles. These multifunctional nanostructures were successfully used as a fluorescent imaging probe and an MRI contrast agent for specifically probing and imaging αvβ3 integrin upregulated tumor cells. The work provides a promising strategy for tumor cell detection by simultaneous fluorescence and MR imaging.Bionanoparticles and nanostructures have attracted increasing interest as versatile and promising tools in many applications including biosensing and bioimaging. In this study, to image and detect tumor cells, ferritin cage-based multifunctional hybrid nanostructures were constructed that: (i) displayed both the green fluorescent protein and an Arg-Gly-Asp peptide on the exterior surface of the ferritin cages; and (ii) incorporated ferrimagnetic iron oxide nanoparticles into the ferritin interior cavity. The overall architecture of ferritin cages did not change after being integrated with fusion proteins and ferrimagnetic iron oxide nanoparticles. These multifunctional nanostructures were successfully used as a fluorescent imaging probe and an MRI contrast agent for specifically probing and imaging αvβ3 integrin upregulated tumor cells. The work provides a promising strategy for tumor cell detection by simultaneous fluorescence and MR imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr11132a

Portable multispectral fluorescence imaging system for food safety applications

NASA Astrophysics Data System (ADS)

Lefcourt, Alan M.; Kim, Moon S.; Chen, Yud-Ren

2004-03-01

Fluorescence can be a sensitive method for detecting food contaminants. Of particular interest is detection of fecal contamination as feces is the source of many pathogenic organisms. Feces generally contain chlorophyll a and related compounds due to ingestion of plant materials, and these compounds can readily be detected using fluorescence techniques. Described is a fluorescence-imaging system consisting primarily of a UV light source, an intensified camera with a six-position filter wheel, and software for controlling the system and automatically analyzing the resulting images. To validate the system, orchard apples artificially contaminated with dairy feces were used in a "hands-on" public demonstration. The contamination sites were easily identified using automated edge detection and threshold detection algorithms. In addition, by applying feces to apples and then washing sets of apples at hourly intervals, it was determined that five h was the minimum contact time that allowed identification of the contamination site after the apples were washed. There are many potential uses for this system, including studying the efficacy of apple washing systems.

Cryo-imaging of fluorescently labeled single cells in a mouse

NASA Astrophysics Data System (ADS)

Steyer, Grant J.; Roy, Debashish; Salvado, Olivier; Stone, Meredith E.; Wilson, David L.

2009-02-01

We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryoimaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 μm) and imaging, collecting color brightfield and fluorescent blockface image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [uT : heart (267 +/- 47.6 μm), liver (218 +/- 27.1 μm), brain (161 +/- 27.4 μm)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97+/-2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns. We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron-scale, fluorescence, and bright field image data. Here we describe our image preprocessing, analysis, and visualization techniques. Processing improves axial resolution, reduces subsurface fluorescence by 97%, and enables single cell detection and counting. High quality 3D volume renderings enable us to evaluate cell distribution patterns. Applications include the myriad of biomedical experiments using fluorescent reporter gene and exogenous fluorophore labeling of cells in applications such as stem cell regenerative medicine, cancer, tissue engineering, etc.

Complete suppression of the fluorophore fluorescence by combined effect of multiple fluorescence quenching groups: A fluorescent sensor for Cu²⁺ with zero background signals.

PubMed

Long, Lingliang; Wu, Yanjun; Wang, Lin; Gong, Aihua; Hu, Rongfeng; Zhang, Chi

2016-02-18

The reaction-based fluorescent sensors have attracted increasing attention in the past decades. However, the application of these sensors for accurate sensing was significantly retarded by the background fluorescence from the sensors themselves. In this work, we demonstrated a novel strategy that the background fluorescence of the sensor could be completely eliminated by the combined effect of multiple fluorescence quenching groups. Based on this new strategy, as proof-of-principle study, a fluorescent sensor (CuFS) for Cu(2+) was judiciously developed. In CuFS, three types of fluorescence quenching groups were directly tethered to a commonly used coumarin fluorophore. The fluorescence of coumarin fluorophore in CuFS was completely suppressed by the combined effect of these fluorescence quenching groups. Upon treatment with 22 μM Cu(2+), sensor CuFS achieved a dramatic fluorescence enhancement (fluorescence intensity enhanced up to 811-fold) centered at 469 nm. The detection limits was determined to be 12.3 nM. The fluorescence intensity enhancement also showed a good linearity with the Cu(2+) concentration in the range of 12.3 nM to 2 μM. By fabricating test strips, sensor CuFS can be utilized as a simple tool to detect Cu(2+) in water samples. Furthermore, the fluorescent sensor was successfully applied in detecting different concentration of Cu(2+) in living cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly sensitive detection of human papillomavirus type 16 DNA using time-resolved fluorescence microscopy and long lifetime probes

NASA Astrophysics Data System (ADS)

Wang, Xue F.; Periasamy, Ammasi; Wodnicki, Pawel; Siadat-Pajouh, M.; Herman, Brian

1995-04-01

We have been interested in the role of Human Papillomavirus (HPV) in cervical cancer and its diagnosis; to that end we have been developing microscopic imaging and fluorescent in situ hybridization (FISH) techniques to genotype and quantitate the amount of HPV present at a single cell level in cervical PAP smears. However, we have found that low levels of HPV DNA are difficult to detect accurately because theoretically obtainable sensitivity is never achieved due to nonspecific autofluorescence, fixative induced fluorescence of cells and tissues, and autofluorescence of the optical components in the microscopic system. In addition, the absorption stains used for PAP smears are intensely autofluorescent. Autofluorescence is a rapidly decaying process with lifetimes in the range of 1-100 nsec, whereas phosphorescence and delayed fluorescence have lifetimes in the range of 1 microsecond(s) ec-10 msec. The ability to discriminate between specific fluorescence and autofluorescence in the time-domain has improved the sensitivity of diagnostic test such that they perform comparably to, or even more sensitive than radioisotopic assays. We have developed a novel time-resolved fluorescence microscope to improve the sensitivity of detection of specific molecules of interest in slide based specimens. This time-resolved fluorescence microscope is based on our recently developed fluorescence lifetime imaging microscopy (FILM) in conjunction with the use of long lifetime fluorescent labels. By using fluorescence in situ hybridization and the long lifetime probe (europium), we have demonstrated the utility of this technique for detection of HPV DNA in cervicovaginal cells. Our results indicate that the use of time-resolved fluorescence microscopy and long lifetime probes increases the sensitivity of detection by removing autofluorescence and will thus lead to improved early diagnosis of cervical cancer. Since the highly sensitive detection of DNA in clinical samples using fluorescence in situ hybridization image is useful for the diagnosis of many other type of diseases, the system we have developed should find numerous applications for the diagnosis of disease states.

Rapid synthesis of N, S co-doped carbon dots and their application for Fe3+ ion detection

NASA Astrophysics Data System (ADS)

Zhang, Jian; Wang, Junbin; Fu, Jinping; Fu, Xucheng; Gan, Wei; Hao, Hequn

2018-02-01

In this study, nitrogen and sulfur co-doped carbon dots (NSCDs) were fabricated by microwave-assisted one-pot synthesis using vitamin C and thiourea as precursors. The as-prepared NSCDs demonstrated excellent properties, including aqueous dispensability, strong fluorescence emission, excellent environmental stability, high selectivity, and sensitivity toward Fe3+ ions. The NSCD-based material can be used as a "turn off" fluorescent probe for detecting Fe3+ ions at a low detection limit (4.2 nM). In addition, the "turn off" and "turn on" of NSCD fluorescent probe could be modulated by adding Fe3+ and EDTA, indicating weak interaction between the Fe3+ ions and NSCDs.

Comparison between immunofluorescence and immunomagnetic techniques of cytometry

NASA Astrophysics Data System (ADS)

Tchikov, V.; Schütze, S.; Krönke, M.

1999-04-01

Magnetophoresis and fluorescence activated cell sorting were used for evaluation of immunochemical properties of magnetic particles and fluorescent probes. The HLA-Bw6 antigen on surfaces of REH cells was detected with a primary monoclonal antibody and a secondary antibody coupled with fluorescent molecules or magnetic particles. Magnetophoresis can find applications in biology and medicine for measuring percentages of cell subpopulations.

Dopamine fluorescent sensors based on polypyrrole/graphene quantum dots core/shell hybrids.

PubMed

Zhou, Xi; Ma, Peipei; Wang, Anqi; Yu, Chenfei; Qian, Tao; Wu, Shishan; Shen, Jian

2015-02-15

A facilely prepared fluorescent sensor was developed for dopamine (DA) detection with high sensitivity and selectivity based on polypyrrole/graphene quantum dots (PPy/GQDs) core/shell hybrids. The composites exhibit strong fluorescence emission, which is dramatically enhanced as high as three times than pristine GQDs. The prepared sensor allows a highly sensitive determination of DA by fluorescent intensity decreasing with the addition of DA and presents a good linearity in range of 5-8000 nM with the detection limit of 10 pM (S/N = 3). Furthermore, the application of the proposed approach have been demonstrated in real samples and showed promise in diagnostic purposes. Copyright © 2014 Elsevier B.V. All rights reserved.

A capillary electrophoresis chip for the analysis of print and film photographic developing agents in commercial processing solutions using indirect fluorescence detection.

PubMed

Sirichai, S; de Mello, A J

2001-01-01

The separation and detection of both print and film developing agents (CD-3 and CD-4) in photographic processing solutions using chip-based capillary electrophoresis is presented. For simultaneous detection of both analytes under identical experimental conditions a buffer pH of 11.9 is used to partially ionise the analytes. Detection is made possible by indirect fluorescence, where the ions of the analytes displace the anionic fluorescing buffer ion to create negative peaks. Under optimal conditions, both analytes can be analyzed within 30 s. The limits of detection for CD-3 and CD-4 are 0.17 mM and 0.39 mM, respectively. The applicability of the method for the analysis of seasoned photographic processing developer solutions is also examined.

Sentinel lymph node detection in gynecologic malignancies by a handheld fluorescence camera

NASA Astrophysics Data System (ADS)

Hirsch, Ole; Szyc, Lukasz; Muallem, Mustafa Zelal; Ignat, Iulia; Chekerov, Radoslav; Macdonald, Rainer; Sehouli, Jalid; Braicu, Ioana; Grosenick, Dirk

2017-02-01

Near-infrared fluorescence imaging using indocyanine green (ICG) as a tracer is a promising technique for mapping the lymphatic system and for detecting sentinel lymph nodes (SLN) during cancer surgery. In our feasibility study we have investigated the application of a custom-made handheld fluorescence camera system for the detection of lymph nodes in gynecological malignancies. It comprises a low cost CCD camera with enhanced NIR sensitivity and two groups of LEDs emitting at wavelengths of 735 nm and 830 nm for interlaced recording of fluorescence and reflectance images of the tissue, respectively. With the help of our system, surgeons can observe fluorescent tissue structures overlaid onto the anatomical image on a monitor in real-time. We applied the camera system for intraoperative lymphatic mapping in 5 patients with vulvar cancer, 5 patients with ovarian cancer, 3 patients with cervical cancer, and 3 patients with endometrial cancer. ICG was injected at four loci around the primary malignant tumor during surgery. After a residence time of typically 15 min fluorescence images were taken in order to visualize the lymph nodes closest to the carcinomas. In cases with vulvar cancer about half of the lymph nodes detected by routinely performed radioactive SLN mapping have shown fluorescence in vivo as well. In the other types of carcinomas several lymph nodes could be detected by fluorescence during laparotomy. We conclude that our low cost camera system has sufficient sensitivity for lymphatic mapping during surgery.

One-pot fabrication of FRET-based fluorescent probe for detecting copper ion and sulfide anion in 100% aqueous media

NASA Astrophysics Data System (ADS)

Lv, Kun; Chen, Jian; Wang, Hong; Zhang, Peisheng; Yu, Maolin; Long, Yunfei; Yi, Pinggui

2017-04-01

The design of effective tools for detecting copper ion (Cu2 +) and sulfide anion (S2 -) is of great importance due to the abnormal level of Cu2 + and S2 - has been associated with an increase in risk of many diseases. Herein, we report on the fabrication of fluorescence resonance energy transfer (FRET) based fluorescent probe PF (PEI-FITC) for detecting Cu2 + and S2 - in 100% aqueous media via a facile one-pot method by covalent linking fluorescein isothiocyanate (FITC) with branched-polyethylenimine (b-PEI). PF could selectively coordinate with Cu2 + among 10 metal ions to form PF-Cu2 + complex, resulting in fluorescence quenching through FRET mechanism. Furthermore, the in situ generated PF-Cu2 + complex can be used to selectively detect S2 - based on the displacement approach, resulting in an off-on type sensing. There is no obvious interference from other anions, such as Cl-, NO3-, ClO4-, SO42 -, HCO3-, CO32 -, Br-, HPO42 -, F- and S2O32 -. In addition, PF was successfully used to determine Cu2 + and S2 - in human serum and tap water samples. Therefore, the FRET-based probe PF may provide a new method for selective detection of multifarious analysts in biological and environmental applications, and even hold promise for application in more complicated systems.

Photonic Crystal Enhanced Fluorescence for Early Breast Cancer Biomarker Detection

PubMed Central

Cunningham, Brian T.; Zangar, Richard C.

2013-01-01

Photonic crystal surfaces offer a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics. Through the complementary processes of photonic crystal enhanced excitation and enhanced extraction, a periodic dielectric-based nanostructured surface can simultaneously increase the electric field intensity experienced by surface-bound fluorophores and increase the collection efficiency of emitted fluorescent photons. Through the ability to inexpensively fabricate photonic crystal surfaces over substantial surface areas, they are amenable to single-use applications in biological sensing, such as disease biomarker detection in serum. In this review, we will describe the motivation for implementing high-sensitivity, multiplexed biomarker detection in the context of breast cancer diagnosis. We will summarize recent efforts to improve the detection limits of such assays though the use of photonic crystal surfaces. Reduction of detection limits is driven by low autofluorescent substrates for photonic crystal fabrication, and detection instruments that take advantage of their unique features. PMID:22736539

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

PubMed Central

Cole, Russell H.; Gartner, Zev J.; Abate, Adam R.

2016-01-01

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein. PMID:27214249

Synthesis of improved upconversion nanoparticles as ultrasensitive fluorescence probe for mycotoxins.

PubMed

Chen, Quansheng; Hu, Weiwei; Sun, Cuicui; Li, Huanhuan; Ouyang, Qin

2016-09-28

Rare earth-doped upconversion nanoparticles (UCNPs) have promising potentials in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This paper reports an improved UCNPs-based fluorescence probe for dual-sensing of Aflatoxin B1 (AFB1) and Deoxynivalenol (DON) using a magnetism-induced separation and the specific formation of antibody-targets complex. Herein, the improved UCNPs, which were namely NaYF4:Yb/Ho/Gd and NaYF4:Yb/Tm/Gd, were systematically studied based on the optimization of reaction time, temperature and the concentration of dopant ions with simultaneous phase and size controlled NaYF4 nanoparticles; and the targets were detected using the pattern of competitive combination assay. Under an optimized condition, the advanced fluorescent probes revealed stronger fluorescent properties, broader biological applications and better storage stabilities compared to traditional UCNPs-based ones; and ultrasensitive determinations of AFB1 and DON were achieved under a wide sensing range of 0.001-0.1 ng ml(-1) with the limit of detection (LOD) of 0.001 ng ml(-1). Additionally, the applicability of the improved nanosensor for the detection of mycotoxins was also confirmed in adulterated oil samples. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel and simple fluorescence probe for detecting main group magnesium ion in HeLa cells and Arabidopsis.

PubMed

Yu, Tingting; Sun, Ping; Hu, Yijie; Ji, Yinggang; Zhou, Hongping; Zhang, Baowei; Tian, Yupeng; Wu, Jieying

2016-12-15

A simple-molecule fluorescence probe L has been designed, synthesized and characterized, which shows high selectivity and sensitivity for the main group magnesium ion through fluorescence "turn-on" response in ethanol solution, and no interference from calcium ion in particular. Detection limit of probe L is 1.47×10(-6) M and the rapid response could reach about 15-20s. The recognition mechanism has been established by fluorescence spectra, (1)H NMR study. Moreover, probe L presents a great photostability, low toxicity and cellular permeability, then we have carried out fluorescent bio-imaging of the probe L for magnesium ions in HeLa cells, which showed that probe L could be utilized to detect the intracellular magnesium ion. Furthermore, it is successfully used as a magnesium ion developer in plant tissues, which shows that it not only can be well tracking the transport of magnesium ion but also make a corresponding fluorescence response to different concentrations magnesium ion. These results would make this probe a great potential application for detecting Mg(2+) in biological system. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

PubMed

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.

Manipulating the Surface Chemistry of Quantum Dots for Sensitive Ratiometric Fluorescence Detection of Sulfur Dioxide.

PubMed

Li, Huihui; Zhu, Houjuan; Sun, Mingtai; Yan, Yehan; Zhang, Kui; Huang, Dejian; Wang, Suhua

2015-08-11

Herein, we report a novel approach to the rapid visual detection of gaseous sulfur dioxide (SO2) by manipulating the surface chemistry of 3-aminopropyltriethoxysilane (APTS)-modified quantum dots (QDs) using fluorescent coumarin-3-carboxylic acid (CCA) for specific reaction with SO2. The CCA molecules are attached to the surface amino groups of the QDs through electrostatic attraction, thus the fluorescence of CCA is greatly suppressed because of the formation of an ion-pair complex between the ATPS-modified QDs and CCA. Such an interaction is vulnerable to SO2 because SO2 can readily react with surface amino groups to form strong charge-transfer complexes and subsequently release the strongly fluorescent CCA molecules. The mechanism has been carefully verified through a series of control experiments. Upon exposure to different amounts of SO2, the fluorescent color of the nanoparticle-based sensor displays continuously changes from red to blue. Most importantly, the approach owns high selectivity for SO2 and a tolerance of interference, which enables the sensor to detect SO2 in a practical application. Using this fluorescence-based sensing method, we have achieved a visual detection limit of 6 ppb for gaseous SO2.

Template-directed synthesis of silica nanotubes for explosive detection.

PubMed

Yildirim, Adem; Acar, Handan; Erkal, Turan S; Bayindir, Mehmet; Guler, Mustafa O

2011-10-01

Fluorescent porous organic-inorganic thin films are of interest of explosive detection because of their vapor phase fluorescence quenching property. In this work, we synthesized fluorescent silica nanotubes using a biomineralization process through self-assembled peptidic nanostructures. We designed and synthesized an amyloid-like peptide self-assembling into nanofibers to be used as a template for silica nanotube formation. The amine groups on the peptide nanofibrous system were used for nucleation of silica nanostructures. Silica nanotubes were used to prepare highly porous surfaces, and they were doped with a fluorescent dye by physical adsorption for explosive sensing. These porous surfaces exhibited fast, sensitive, and highly selective fluorescence quenching against nitro-explosive vapors. The materials developed in this work have vast potential in sensing applications due to enhanced surface area. © 2011 American Chemical Society

A dual spectroscopic fluorescence probe based on carbon dots for detection of 2,4,6-trinitrophenol/Fe (III) ion by fluorescence and frequency doubling scattering spectra and its analytical applications.

PubMed

Xu, Jinxia; Bai, Zhangjun; Zu, Fanlin; Yan, Fanyong; Wei, Junfu; Zhang, Saihui; Luo, Yunmei

2018-07-05

A convenient, highly sensitive and reliable assay for 2,4,6‑trinitrophenol (TNP) and Fe (III) ion (Fe 3+ ) in the dual spectroscopic manner is developed based on novel carbon dots (CDs). The CDs with highly blue emitting fluorescent were easily prepared via the one-step potassium hydroxide-assisted reflux method from dextrin. The as-synthesized CDs exhibited the high crystalline quality, the excellent fluorescence characteristics with a high quantum yield of ~13.1%, and the narrow size distribution with an average diameter of 6.3±0.5nm. Fluorescence and frequency doubling scattering (FDS) spectra of CDs show the unique changes in the presence of TNP/Fe 3+ by different mechanism. The fluorescence of CDs decreased apparently in the presence of TNP via electron-transfer. Thus, after the experimental conditions were optimized, the linear range for detection TNP is 0-50μM, the detection limit was 19.1nM. With the addition of Fe 3+ , the FDS of CDs appeared to be highly sensitive with a quick response to Fe 3+ as a result of the change concentration of the scattering particle. The emission peak for FDS at 450nm was enhanced under the excitation wavelength at 900nm. The fluorescence response changes linearly with Fe 3+ concentration in the range of 8-40μM, the detection limits were determined to be 44.1nM. The applications of CDs were extended for the detection of TNP, Fe 3+ in real water samples with a high recovery. The results reported here may become the potential tools for the fast response of TNP and Fe 3+ in the analysis of environmental pollutants. Copyright © 2018 Elsevier B.V. All rights reserved.

Broadly Applicable Strategy for the Fluorescence Based Detection and Differentiation of Glutathione and Cysteine/Homocysteine: Demonstration in Vitro and in Vivo.

PubMed

Chen, Wenqiang; Luo, Hongchen; Liu, Xingjiang; Foley, James W; Song, Xiangzhi

2016-04-05

Glutathione (GSH), cysteine (Cys), and homocysteine (Hcy) are small biomolecular thiols that are present in all cells and extracellular fluids of healthy mammals. It is well-known that each plays a separate, critically important role in human physiology and that abnormal levels of each are predictive of a variety of different disease states. Although a number of fluorescence-based methods have been developed that can detect biomolecules that contain sulfhydryl moieties, few are able to differentiate between GSH and Cys/Hcy. In this report, we demonstrate a broadly applicable approach for the design of fluorescent probes that can achieve this goal. The strategy we employ is to conjugate a fluorescence-quenching 7-nitro-2,1,3-benzoxadiazole (NBD) moiety to a selected fluorophore (Dye) through a sulfhydryl-labile ether linkage to afford nonfluorescent NBD-O-Dye. In the presence of GSH or Cys/Hcy, the ether bond is cleaved with the concomitant generation of both a nonfluorescent NBD-S-R derivative and a fluorescent dye having a characteristic intense emission band (B1). In the special case of Cys/Hcy, the NBD-S-Cys/Hcy cleavage product can undergo a further, rapid, intramolecular Smiles rearrangement to form a new, highly fluorescent NBD-N-Cys/Hcy compound (band B2); because of geometrical constraints, the GSH derived NBD-S-GSH derivative cannot undergo a Smiles rearrangement. Thus, the presence of a single B1 or double B1 + B2 signature can be used to detect and differentiate GSH from Cys/Hcy, respectively. We demonstrate the broad applicability of our approach by including in our studies members of the Flavone, Bodipy, and Coumarin dye families. Particularly, single excitation wavelength could be applied for the probe NBD-OF in the detection of GSH over Cys/Hcy in both aqueous solution and living cells.

Protoporphyrin IX fluorescence as potential indicator of psoriasis severity and progression.

PubMed

Wang, Bo; Xu, Yu-Ting; Zhang, Li; Zheng, Jie; Sroka, Ronald; Wang, Hong-Wei; Wang, Xiu-Li

2017-09-01

In psoriatic lesions, fluorescence diagnosis with blue light can detect protoporphyrin IX accumulation, especially after topical 5-aminolaevulinic acid (ALA) application. However, variable fluorescence distributions, interpersonal variations and long incubation time limit its wide application in clinic. This study is aimed to identify a consistent and convenient method to facilitate diagnosis and evaluation of psoriatic lesions. 104 psoriatic lesions from 30 patients were evaluated. Single lesion PSI scoring and fluorescence by macrospectrofluorometry were recorded on each lesion before and after treatment with narrow-band UVB. Punctate red fluorescence, emitted mainly by protoporphyrin IX, is observed in some psoriatic lesions. According to psoriasis severity index, fluorescence-positive lesions are more severe than lesions without fluorescence. We found a significant positive correlation between psoriasis severity and fluorescence intensity from protoporphyrin IX. Protoporphyrin IX-induced red fluorescence can be used as a novel and convenient approach for psoriasis diagnosis and progression evaluation. Copyright © 2017. Published by Elsevier B.V.

Femtogram detection of explosive nitroaromatics: fluoranthene-based fluorescent chemosensors.

PubMed

Venkatramaiah, N; Kumar, Shiv; Patil, Satish

2012-11-12

Herein we report a novel fluoranthene-based fluorescent fluorophore 7,10-bis(4-bromophenyl)-8,9-bis[4-(hexyloxy)phenyl]fluoranthene (S(3)) and its remarkable properties in applications of explosive detection. The sensitivity towards the detection of nitroaromatics (NACs) was evaluated through fluorescence quenching in solution, vapor, and contact mode approaches. The contact mode approach using thin-layer silica chromatographic plates exhibited a femtogram (1.15 fg cm(-2)) detection limit for trinitrotoluene (TNT) and picric acid (PA), whereas the solution-phase quenching showed PA detection at the 2-20 ppb level. Fluorescence lifetime measurements revealed that the quenching is static in nature and the quenching process is fully reversible. Binding energies between model binding sites of the S(3) and analyte compounds reveal that analyte molecules enter into the cavity created by substituted phenyl rings of fluoranthene and are stabilized by strong intermolecular interactions with alkyl chains. It is anticipated that the sensor S(3) could be a promising material for the construction of portable optical devices for the detection of onsite explosive nitroaromatics. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diketopyrrolopyrrole: brilliant red pigment dye-based fluorescent probes and their applications.

PubMed

Kaur, Matinder; Choi, Dong Hoon

2015-01-07

The development of fluorescent probes for the detection of biologically relevant species is a burgeoning topic in the field of supramolecular chemistry. A number of available dyes such as rhodamine, coumarin, fluorescein, and cyanine have been employed in the design and synthesis of new fluorescent probes. However, diketopyrrolopyrrole (DPP) and its derivatives have a distinguished role in supramolecular chemistry for the design of fluorescent dyes. DPP dyes offer distinctive advantages relative to other organic dyes, including high fluorescence quantum yields and good light and thermal stability. Significant advancements have been made in the development of new fluorescent probes based on DPP in recent years as a result of tireless research efforts by the chemistry scientific community. In this tutorial review, we highlight the recent progress in the development of DPP-based fluorescent probes for the period spanning 2009 to the present time and the applications of these probes to recognition of biologically relevant species including anions, cations, reactive oxygen species, thiols, gases and other miscellaneous applications. This review is targeted toward providing the readers with deeper understanding for the future design of DPP-based fluorogenic probes for chemical and biological applications.

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

NASA Astrophysics Data System (ADS)

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

An ultra-small, multi-point, and multi-color photo-detection system with high sensitivity and high dynamic range.

PubMed

Anazawa, Takashi; Yamazaki, Motohiro

2017-12-05

Although multi-point, multi-color fluorescence-detection systems are widely used in various sciences, they would find wider applications if they are miniaturized. Accordingly, an ultra-small, four-emission-point and four-color fluorescence-detection system was developed. Its size (space between emission points and a detection plane) is 15 × 10 × 12 mm, which is three-orders-of-magnitude smaller than that of a conventional system. Fluorescence from four emission points with an interval of 1 mm on the same plane was respectively collimated by four lenses and split into four color fluxes by four dichroic mirrors. Then, a total of sixteen parallel color fluxes were directly input into an image sensor and simultaneously detected. The emission-point plane and the detection plane (the image-sensor surface) were parallel and separated by a distance of only 12 mm. The developed system was applied to four-capillary array electrophoresis and successfully achieved Sanger DNA sequencing. Moreover, compared with a conventional system, the developed system had equivalent high fluorescence-detection sensitivity (lower detection limit of 17 pM dROX) and 1.6-orders-of-magnitude higher dynamic range (4.3 orders of magnitude).

Simultaneous multicolor detection system of the single-molecular microbial antigen by total internal reflection fluorescence microscopy with fluorescent nanocrystal quantum dots

NASA Astrophysics Data System (ADS)

Hoshino, Akiyoshi; Fujioka, Kouki; Yamamoto, Mayu; Manabe, Noriyoshi; Yasuhara, Masato; Suzuki, Kazuo; Yamamoto, Kenji

2005-11-01

Immunological diagnostic methods have been widely performed and showed high performance in molecular and cellular biology, molecular imaging, and medical diagnostics. We have developed novel methods for the fluorescent labeling of several antibodies coupled with fluorescent nanocrystals QDs. In this study we demonstrated that two bacterial toxins, diphtheria toxin and tetanus toxin, were detected simultaneously in the same view field of a cover slip by using directly QD-conjugated antibodies. We have succeeded in detecting bacterial toxins by counting luminescent spots on the evanescent field with using primary antibody conjugated to QDs. In addition, each bacterial toxin in the mixture can be separately detected by single excitation laser with emission band pass filters, and simultaneously in situ pathogen quantification was performed by calculating the luminescent density on the surface of the cover slip. Our results demonstrate that total internal reflection fluorescence microscopy (TIRFM) enables us to distinguish each antigen from mixed samples and can simultaneously quantitate multiple antigens by QD-conjugated antibodies. Bioconjugated QDs could have great potentialities for in practical biomedical applications to develop various high-sensitivity detection systems.

A new large solid angle multi-element silicon drift detector system for low energy X-ray fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Bufon, J.; Schillani, S.; Altissimo, M.; Bellutti, P.; Bertuccio, G.; Billè, F.; Borghes, R.; Borghi, G.; Cautero, G.; Cirrincione, D.; Fabiani, S.; Ficorella, F.; Gandola, M.; Gianoncelli, A.; Giuressi, D.; Kourousias, G.; Mele, F.; Menk, R. H.; Picciotto, A.; Rachevski, A.; Rashevskaya, I.; Sammartini, M.; Stolfa, A.; Zampa, G.; Zampa, N.; Zorzi, N.; Vacchi, A.

2018-03-01

Low-energy X-ray fluorescence (LEXRF) is an essential tool for bio-related research of organic samples, whose composition is dominated by light elements. Working at energies below 2 keV and being able to detect fluorescence photons of lightweight elements such as carbon (277 eV) is still a challenge, since it requires in-vacuum operations to avoid in-air photon absorption. Moreover, the detectors must have a thin entrance window and collect photons at an angle of incidence near 90 degrees to minimize the absorption by the protective coating. Considering the low fluorescence yield of light elements, it is important to cover a substantial part of the solid angle detecting ideally all emitted X-ray fluorescence (XRF) photons. Furthermore, the energy resolution of the detection system should be close to the Fano limit in order to discriminate elements whose XRF emission lines are often very close within the energy spectra. To ensure all these features, a system consisting of four monolithic multi-element silicon drift detectors was developed. The use of four separate detector units allows optimizing the incidence angle on all the sensor elements. The multi-element approach in turn provides a lower leakage current on each anode, which, in combination with ultra-low noise preamplifiers, is necessary to achieve an energy resolution close to the Fano limit. The potential of the new detection system and its applicability for typical LEXRF applications has been proved on the Elettra TwinMic beamline.

An integrated optics microfluidic device for detecting single DNA molecules.

PubMed

Krogmeier, Jeffrey R; Schaefer, Ian; Seward, George; Yantz, Gregory R; Larson, Jonathan W

2007-12-01

A fluorescence-based integrated optics microfluidic device is presented, capable of detecting single DNA molecules in a high throughput and reproducible manner. The device integrates microfluidics for DNA stretching with two optical elements for single molecule detection (SMD): a plano-aspheric refractive lens for fluorescence excitation (illuminator) and a solid parabolic reflective mirror for fluorescence collection (collector). Although miniaturized in size, both optical components were produced and assembled onto the microfluidic device by readily manufacturable fabrication techniques. The optical resolution of the device is determined by the small and relatively low numerical aperture (NA) illuminator lens (0.10 effective NA, 4.0 mm diameter) that delivers excitation light to a diffraction limited 2.0 microm diameter spot at full width half maximum within the microfluidic channel. The collector (0.82 annular NA, 15 mm diameter) reflects the fluorescence over a large collection angle, representing 71% of a hemisphere, toward a single photon counting module in an infinity-corrected scheme. As a proof-of-principle experiment for this simple integrated device, individual intercalated lambda-phage DNA molecules (48.5 kb) were stretched in a mixed elongational-shear microflow, detected, and sized with a fluorescence signal to noise ratio of 9.9 +/-1.0. We have demonstrated that SMD does not require traditional high numerical aperture objective lenses and sub-micron positioning systems conventionally used in many applications. Rather, standard manufacturing processes can be combined in a novel way that promises greater accessibility and affordability for microfluidic-based single molecule applications.

Exploiting fluorescence for multiplex immunoassays on protein microarrays

NASA Astrophysics Data System (ADS)

Herbáth, Melinda; Papp, Krisztián; Balogh, Andrea; Matkó, János; Prechl, József

2014-09-01

Protein microarray technology is becoming the method of choice for identifying protein interaction partners, detecting specific proteins, carbohydrates and lipids, or for characterizing protein interactions and serum antibodies in a massively parallel manner. Availability of the well-established instrumentation of DNA arrays and development of new fluorescent detection instruments promoted the spread of this technique. Fluorescent detection has the advantage of high sensitivity, specificity, simplicity and wide dynamic range required by most measurements. Fluorescence through specifically designed probes and an increasing variety of detection modes offers an excellent tool for such microarray platforms. Measuring for example the level of antibodies, their isotypes and/or antigen specificity simultaneously can offer more complex and comprehensive information about the investigated biological phenomenon, especially if we take into consideration that hundreds of samples can be measured in a single assay. Not only body fluids, but also cell lysates, extracted cellular components, and intact living cells can be analyzed on protein arrays for monitoring functional responses to printed samples on the surface. As a rapidly evolving area, protein microarray technology offers a great bulk of information and new depth of knowledge. These are the features that endow protein arrays with wide applicability and robust sample analyzing capability. On the whole, protein arrays are emerging new tools not just in proteomics, but glycomics, lipidomics, and are also important for immunological research. In this review we attempt to summarize the technical aspects of planar fluorescent microarray technology along with the description of its main immunological applications.

Chamber catalogues of optical and fluorescent signatures distinguish bioaerosol classes

NASA Astrophysics Data System (ADS)

Hernandez, Mark; Perring, Anne E.; McCabe, Kevin; Kok, Greg; Granger, Gary; Baumgardner, Darrel

2016-07-01

Rapid bioaerosol characterization has immediate applications in the military, environmental and public health sectors. Recent technological advances have facilitated single-particle detection of fluorescent aerosol in near real time; this leverages controlled ultraviolet exposures with single or multiple wavelengths, followed by the characterization of associated fluorescence. This type of ultraviolet induced fluorescence has been used to detect airborne microorganisms and their fragments in laboratory studies, and it has been extended to field studies that implicate bioaerosol to compose a substantial fraction of supermicron atmospheric particles. To enhance the information yield that new-generation fluorescence instruments can provide, we report the compilation of a referential aerobiological catalogue including more than 50 pure cultures of common airborne bacteria, fungi and pollens, recovered at water activity equilibrium in a mesoscale chamber (1 m3). This catalogue juxtaposes intrinsic optical properties and select bandwidths of fluorescence emissions, which manifest to clearly distinguish between major classes of airborne microbes and pollens.

An analog filter approach to frequency domain fluorescence spectroscopy

DOE PAGES

Trainham, Clifford P.; O'Neill, Mary D.; McKenna, Ian J.

2015-10-01

The rate equations found in frequency domain fluorescence spectroscopy are the same as those found in electronics under analog filter theory. Laplace transform methods are a natural way to solve the equations, and the methods can provide solutions for arbitrary excitation functions. The fluorescence terms can be modeled as circuit components and cascaded with drive and detection electronics to produce a global transfer function. Electronics design tools such as Spicea can be used to model fluorescence problems. In applications, such as remote sensing, where detection electronics are operated at high gain and limited bandwidth, a global modeling of the entiremore » system is important, since the filter terms of the drive and detection electronics affect the measured response of the fluorescence signals. Furthermore, the techniques described here can be used to separate signals from fast and slow fluorophores emitting into the same spectral band, and data collection can be greatly accelerated by means of a frequency comb driver waveform and appropriate signal processing of the response.« less

Focus on quantum dots as potential fluorescent probes for monitoring food toxicants and foodborne pathogens.

PubMed

Vinayaka, A C; Thakur, M S

2010-06-01

Water-soluble quantum dots (QDs) are fluorescent semiconductor nanoparticles with narrow, very specific, stable emission spectra. Therefore, the bioconjugation of these QDs for biological fluorescent labeling may be of interest due to their unique physical and optical properties as compared to organic fluorescent dyes. These intrinsic properties of QDs have been used for the sensitive detection of target analytes. From the viewpoint of ensuring food safety, there is a need to develop rapid, sensitive and specific detection techniques to monitor food toxicants in food and environmental samples. Even trace levels of these toxicants can inadvertently enter the food chain, creating severe health hazards. The present review emphasizes the application of water-soluble bioconjugated QDs for the detection of food contaminants such as pesticides, pathogenic bacterial toxins such as botulinum toxin, enterotoxins produced by Staphylococcus aureus, Escherichia coli, and for the development of oligonucleotide-based microarrays. This review also emphasizes the application of a possible resonance energy transfer phenomenon resulting from nanobiomolecular interactions obtained through the bioconjugation of QDs with biomolecules. Furthermore, the utilization of significant changes in the spectral behavior of QDs (attributed to resonance energy transfer in the bioconjugate) in future nanobiosensor development is also emphasized.

Use of x-ray fluorescence for in-situ detection of metals

NASA Astrophysics Data System (ADS)

Elam, W. T. E.; Whitlock, Robert R.; Gilfrich, John V.

1995-01-01

X-ray fluorescence (XRF) is a well-established, non-destructive method of determining elemental concentrations at ppm levels in complex samples. It can operate in atmosphere with no sample preparation, and provides accuracies of 1% or better under optimum conditions. This report addresses two sets of issues concerning the use of x-ray fluorescence as a sensor technology for the cone penetrometer, for shipboard waste disposal, or for other in-situ, real- time environmental applications. The first issue concerns the applicability of XRF to these applications, and includes investigation of detection limits and matrix effects. We have evaluated the detection limits and quantitative accuracy of a sensor mock-up for metals in soils under conditions expected in the field. In addition, several novel ways of improving the lower limits of detection to reach the drinking water regulatory limits have been explored. The second issue is the engineering involved with constructing a spectrometer within the 1.75 inch diameter of the penetrometer pipe, which is the most rigorous physical constraint. Only small improvements over current state-of-the-art are required. Additional advantages of XRF are that no radioactive sources or hazardous materials are used in the sensor design, and no reagents or any possible sources of ignition are involved.

Molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin.

PubMed

Wang, Xiaoyan; Yu, Jialuo; Kang, Qi; Shen, Dazhong; Li, Jinhua; Chen, Lingxin

2016-03-15

A facile strategy was developed to prepare molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin (PC) based on fluorescence resonance energy transfer (FRET), via a sol-gel polymerization process using nitrobenzoxadiazole (NBD) as fluorescent signal source. The ratio of two fluorescence peak emission intensities of NBD and PC was utilized to determine the concentration of PC, which could effectively reduce the background interference and fluctuation of diverse conditions. As a result, this sensor obtained high sensitivity with a low detection limit of 0.14 nM within 6 min, and excellent recognition specificity for PC over its analogues with a high imprinting factor of 9.1. Furthermore, the sensor attained high recoveries in the range of 93.8-110.2% at three spiking levels of PC, with precisions below 4.7% in seawater and lake water samples. The developed sensor strategy demonstrated simplicity, reliability, rapidity, high selectivity and high sensitivity, proving to be a feasible way to develop high efficient fluorescence sensors and thus potentially applicable for ultratrace analysis of complicated matrices. Copyright © 2015 Elsevier B.V. All rights reserved.

One-Step Synthesis of Fluorescent Boron Nitride Quantum Dots via a Hydrothermal Strategy Using Melamine as Nitrogen Source for the Detection of Ferric Ions.

PubMed

Huo, Bingbing; Liu, Bingping; Chen, Tao; Cui, Liang; Xu, Gengfang; Liu, Mengli; Liu, Jingquan

2017-10-10

A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe 3+ with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 μM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling.

Simultaneous fluorescence and quantitative phase microscopy with single-pixel detectors

NASA Astrophysics Data System (ADS)

Liu, Yang; Suo, Jinli; Zhang, Yuanlong; Dai, Qionghai

2018-02-01

Multimodal microscopy offers high flexibilities for biomedical observation and diagnosis. Conventional multimodal approaches either use multiple cameras or a single camera spatially multiplexing different modes. The former needs expertise demanding alignment and the latter suffers from limited spatial resolution. Here, we report an alignment-free full-resolution simultaneous fluorescence and quantitative phase imaging approach using single-pixel detectors. By combining reference-free interferometry with single-pixel detection, we encode the phase and fluorescence of the sample in two detection arms at the same time. Then we employ structured illumination and the correlated measurements between the sample and the illuminations for reconstruction. The recovered fluorescence and phase images are inherently aligned thanks to single-pixel detection. To validate the proposed method, we built a proof-of-concept setup for first imaging the phase of etched glass with the depth of a few hundred nanometers and then imaging the fluorescence and phase of the quantum dot drop. This method holds great potential for multispectral fluorescence microscopy with additional single-pixel detectors or a spectrometer. Besides, this cost-efficient multimodal system might find broad applications in biomedical science and neuroscience.

A Label-Free Aptasensor for Ochratoxin a Detection Based on the Structure Switch of Aptamer.

PubMed

Liu, Feng; Ding, Ailing; Zheng, Jiushang; Chen, Jiucun; Wang, Bin

2018-06-01

A label-free sensing platform is developed based on switching the structure of aptamer for highly sensitive and selective fluorescence detection of ochratoxin A (OTA). OTA induces the structure of aptamer, transforms into G-quadruplex and produces strong fluorescence in the presence of zinc(II)-protoporphyrin IX probe due to the specific bind to G-quadruplex. The simple method exhibits high sensitivity towards OTA with a detection limit of 0.03 nM and excellent selectivity over other mycotoxins. In addition, the successful detection of OTA in real samples represents a promising application in food safety.

Fast and Selective Two-Stage Ratiometric Fluorescent Probes for Imaging of Glutathione in Living Cells.

PubMed

Gong, Deyan; Han, Shi-Chong; Iqbal, Anam; Qian, Jing; Cao, Ting; Liu, Wei; Liu, Weisheng; Qin, Wenwu; Guo, Huichen

2017-12-19

Two fluorescent, m-nitrophenol-substituted difluoroboron dipyrromethene dyes have been designed by nucleophilic substitution reaction of 3,5-dichloro-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). Nonsymmetric and symmetric probes, that is. BODIPY 1 (with one nitrophenol group at the position 3) and BODIPY 2 (with two nitrophenol groups at the positions 3 and 5) were applied to ratiometric fluorescent glutathione detection. The detection is based on the two-step nucleophilic aromatic substitution of the nitrophenol groups of the probes by glutathione in buffer solution containing CTAB. In the first stage, probe 1 showed ratiometric fluorescent color change from green (λ em = 530 nm) to yellow (λ em = 561 nm) because of monosubstitution with glutathione (I 561nm /I 530nm ). Addition of excess glutathione caused the second stage of ratiometric fluorescent color change from yellow to reddish orange (λ em = 596 nm, I 596nm /I 561nm ) due to disubstitution with glutathione. Therefore, different concentration ranges of glutathione (from less to excess) could be rapidly detected by the two-stage ratiometric fluorescent probe 1 in 5 min. While, probe 2 shows single-stage ratiometric fluorescent detection to GSH (from green to reddish orange, I 596nm /I 535nm ). Probes 1 and 2 exhibit excellent properties with sensitive, specific colorimetric response and ratiometric fluorescent response to glutathione over other sulfur nucleophiles. Application to cellular ratiometric fluorescence imaging indicated that the probes were highly responsive to intracellular glutathione.

Detection of the Dinozoans Pfiesteria piscicida and P. shumwayae: a review of detection methods and geographic distribution.

PubMed

Rublee, Parke A; Remington, David L; Schaefer, Eric F; Marshall, Michael M

2005-01-01

Molecular methods, including conventional PCR, real-time PCR, denaturing gradient gel electrophoresis, fluorescent fragment detection PCR, and fluorescent in situ hybridization, have all been developed for use in identifying and studying the distribution of the toxic dinoflagellates Pfiesteria piscicida and P. shumwayae. Application of the methods has demonstrated a worldwide distribution of both species and provided insight into their environmental tolerance range and temporal changes in distribution. Genetic variability among geographic locations generally appears low in rDNA genes, and detection of the organisms in ballast water is consistent with rapid dispersal or high gene flow among populations, but additional sequence data are needed to verify this hypothesis. The rapid development and application of these tools serves as a model for study of other microbial taxa and provides a basis for future development of tools that can simultaneously detect multiple targets.

Quantum dots versus organic fluorophores in fluorescent deep-tissue imaging--merits and demerits.

PubMed

Bakalova, Rumiana; Zhelev, Zhivko; Gadjeva, Veselina

2008-12-01

The use of fluorescence in deep-tissue imaging is rapidly expanding in last several years. The progress in fluorescent molecular probes and fluorescent imaging techniques gives an opportunity to detect single cells and even molecular targets in live organisms. The highly sensitive and high-speed fluorescent molecular sensors and detection devices allow the application of fluorescence in functional imaging. With the development of novel bright fluorophores based on nanotechnologies and 3D fluorescence scanners with high spatial and temporal resolution, the fluorescent imaging has a potential to become an alternative of the other non-invasive imaging techniques as magnetic resonance imaging, positron-emission tomography, X-ray, computing tomography. The fluorescent imaging has also a potential to give a real map of human anatomy and physiology. The current review outlines the advantages of fluorescent nanoparticles over conventional organic dyes in deep-tissue imaging in vivo and defines the major requirements to the "perfect fluorophore". The analysis proceeds from the basic principles of fluorescence and major characteristics of fluorophores, light-tissue interactions, and major limitations of fluorescent deep-tissue imaging. The article is addressed to a broad readership - from specialists in this field to university students.

Ultrastructural localisation of protein interactions using conditionally stable nanobodies.

PubMed

Ariotti, Nicholas; Rae, James; Giles, Nichole; Martel, Nick; Sierecki, Emma; Gambin, Yann; Hall, Thomas E; Parton, Robert G

2018-04-01

We describe the development and application of a suite of modular tools for high-resolution detection of proteins and intracellular protein complexes by electron microscopy (EM). Conditionally stable GFP- and mCherry-binding nanobodies (termed csGBP and csChBP, respectively) are characterized using a cell-free expression and analysis system and subsequently fused to an ascorbate peroxidase (APEX) enzyme. Expression of these cassettes alongside fluorescently labelled proteins results in recruitment and stabilisation of APEX, whereas unbound APEX nanobodies are efficiently degraded by the proteasome. This greatly simplifies correlative analyses, enables detection of less-abundant proteins, and eliminates the need to balance expression levels between fluorescently labelled and APEX nanobody proteins. Furthermore, we demonstrate the application of this system to bimolecular complementation ('EM split-fluorescent protein'), for localisation of protein-protein interactions at the ultrastructural level.

Ultrastructural localisation of protein interactions using conditionally stable nanobodies

PubMed Central

Ariotti, Nicholas; Rae, James; Giles, Nichole; Martel, Nick; Sierecki, Emma; Gambin, Yann; Parton, Robert G.

2018-01-01

We describe the development and application of a suite of modular tools for high-resolution detection of proteins and intracellular protein complexes by electron microscopy (EM). Conditionally stable GFP- and mCherry-binding nanobodies (termed csGBP and csChBP, respectively) are characterized using a cell-free expression and analysis system and subsequently fused to an ascorbate peroxidase (APEX) enzyme. Expression of these cassettes alongside fluorescently labelled proteins results in recruitment and stabilisation of APEX, whereas unbound APEX nanobodies are efficiently degraded by the proteasome. This greatly simplifies correlative analyses, enables detection of less-abundant proteins, and eliminates the need to balance expression levels between fluorescently labelled and APEX nanobody proteins. Furthermore, we demonstrate the application of this system to bimolecular complementation (‘EM split-fluorescent protein’), for localisation of protein–protein interactions at the ultrastructural level. PMID:29621251

Fluorescent carbon nanoparticle-based lateral flow biosensor for ultrasensitive detection of DNA.

PubMed

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.

Carbon nanoparticle for highly sensitive and selective fluorescent detection of mercury(II) ion in aqueous solution.

PubMed

Li, Hailong; Zhai, Junfeng; Tian, Jingqi; Luo, Yonglan; Sun, Xuping

2011-08-15

In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg(2+) detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π-π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg(2+), T-Hg(2+)-T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10nM was achieved. The present CNP-based biosensor for Hg(2+) detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg(2+) detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg(2+) detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development. Copyright © 2011 Elsevier B.V. All rights reserved.

Immuno-magnetic beads-based extraction-capillary zone electrophoresis-deep UV laser-induced fluorescence analysis of erythropoietin.

PubMed

Wang, Heye; Dou, Peng; Lü, Chenchen; Liu, Zhen

2012-07-13

Erythropoietin (EPO) is an important glycoprotein hormone. Recombinant human EPO (rhEPO) is an important therapeutic drug and can be also used as doping reagent in sports. The analysis of EPO glycoforms in pharmaceutical and sports areas greatly challenges analytical scientists from several aspects, among which sensitive detection and effective and facile sample preparation are two essential issues. Herein, we investigated new possibilities for these two aspects. Deep UV laser-induced fluorescence detection (deep UV-LIF) was established to detect the intrinsic fluorescence of EPO while an immuno-magnetic beads-based extraction (IMBE) was developed to specifically extract EPO glycoforms. Combined with capillary zone electrophoresis (CZE), CZE-deep UV-LIF allows high resolution glycoform profiling with improved sensitivity. The detection sensitivity was improved by one order of magnitude as compared with UV absorbance detection. An additional advantage is that the original glycoform distribution can be completely preserved because no fluorescent labeling is needed. By combining IMBE with CZE-deep UV-LIF, the overall detection sensitivity was 1.5 × 10⁻⁸ mol/L, which was enhanced by two orders of magnitude relative to conventional CZE with UV absorbance detection. It is applicable to the analysis of pharmaceutical preparations of EPO, but the sensitivity is insufficient for the anti-doping analysis of EPO in blood and urine. IMBE can be straightforward and effective approach for sample preparation. However, antibodies with high specificity were the key for application to urine samples because some urinary proteins can severely interfere the immuno-extraction. Copyright © 2012 Elsevier B.V. All rights reserved.

A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3+ and its practical application.

PubMed

Zhang, Shanshan; Sun, Tao; Xiao, Dejun; Yuan, Fang; Li, Tianduo; Wang, Enhua; Liu, Haixia; Niu, Qingfen

2018-01-15

A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe 3+ detection was designed and synthesized. In presence of Fe 3+ , sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe 3+ complex was found as 2.4×10 4 with the lower detection limit of 14.3nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1 H NMR spectra. Sensor L for Fe 3+ detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe 3+ ions in practical water samples with good recovery. Copyright © 2017 Elsevier B.V. All rights reserved.

One-step synthesis of nitrogen, boron co-doped fluorescent carbon nanoparticles for glucose detection.

PubMed

Liang, Meijuan; Ren, Yi; Zhang, Haijuan; Ma, Yunxia; Niu, Xiaoying; Chen, Xingguo

2017-09-01

Heteroatom-doped carbon nanoparticles (CNPs) have attracted considerable attention due to an effective improvement in their intrinsic properties. Here, a facile and simple synthesis of nitrogen, boron co-doped carbon nanoparticles (NB-CNPs) from a sole precursor, 3-aminophenylboronic acid, was performed via a one-step solid-phase approach. Because of the presence of boronic acid, NB-CNPs can be used directly as a fluorescent probe for glucose. Based on a boronic acid-triggered specific reaction, we developed a simple NB-CNP probe without surface modification for the detection of glucose. When glucose was introduced, the fluorescence of NB-CNPs was suppressed through a surface-quenching states mechanism. Obvious fluorescence quenching allowed the highly sensitive determination of glucose with a limit of detection of 1.8 μM. Moreover, the proposed method has been successfully used to detect glucose in urine from people with diabetes, suggesting potential application in sensing glucose. Copyright © 2017 John Wiley & Sons, Ltd.

Active substrates improving sensitivity in biomedical fluorescence microscopy

NASA Astrophysics Data System (ADS)

Le Moal, E.; Leveque-Fort, S.; Fort, E.; Lacharme, J.-P.; Fontaine-Aupart, M.-P.; Ricolleau, C.

2005-08-01

Fluorescence is widely used as a spectroscopic tool or for biomedical imaging, in particular for DNA chips. In some cases, detection of very low molecular concentrations and precise localization of biomarkers are limited by the weakness of the fluorescence signal. We present a new method based on sample substrates that improve fluorescence detection sensitivity. These active substrates consist in glass slides covered with metal (gold or silver) and dielectric (alumina) films and can directly be used with common microscope set-up. Fluorescence enhancement affects both excitation and decay rates and is strongly dependant on the distance to the metal surface. Furthermore, fluorescence collection is improved since fluorophore emission lobes are advantageously modified close to a reflective surface. Finally, additional improvements are achieved by structuring the metallic layer. Substrates morphology was mapped by Atomic Force Microscopy (AFM). Substrates optical properties were studied using mono- and bi-photonic fluorescence microscopy with time resolution. An original set-up was implemented for spatial radiation pattern's measurement. Detection improvement was then tested on commercial devices. Several biomedical applications are presented. Enhancement by two orders of magnitude are achieved for DNA chips and signal-to-noise ratio is greatly increased for cells imaging.

A coumarin based Schiff base probe for selective fluorescence detection of Al3 + and its application in live cell imaging

NASA Astrophysics Data System (ADS)

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.

Calibration approach for fluorescence lifetime determination for applications using time-gated detection and finite pulse width excitation.

PubMed

Keller, Scott B; Dudley, Jonathan A; Binzel, Katherine; Jasensky, Joshua; de Pedro, Hector Michael; Frey, Eric W; Urayama, Paul

2008-10-15

Time-gated techniques are useful for the rapid sampling of excited-state (fluorescence) emission decays in the time domain. Gated detectors coupled with bright, economical, nanosecond-pulsed light sources like flashlamps and nitrogen lasers are an attractive combination for bioanalytical and biomedical applications. Here we present a calibration approach for lifetime determination that is noniterative and that does not assume a negligible instrument response function (i.e., a negligible excitation pulse width) as does most current rapid lifetime determination approaches. Analogous to a transducer-based sensor, signals from fluorophores of known lifetime (0.5-12 ns) serve as calibration references. A fast avalanche photodiode and a GHz-bandwidth digital oscilloscope is used to detect transient emission from reference samples excited using a nitrogen laser. We find that the normalized time-integrated emission signal is proportional to the lifetime, which can be determined with good reproducibility (typically <100 ps) even for data with poor signal-to-noise ratios ( approximately 20). Results are in good agreement with simulations. Additionally, a new time-gating scheme for fluorescence lifetime imaging applications is proposed. In conclusion, a calibration-based approach is a valuable analysis tool for the rapid determination of lifetime in applications using time-gated detection and finite pulse width excitation.

Optimal optical filters of fluorescence excitation and emission for poultry fecal detection

USDA-ARS?s Scientific Manuscript database

Purpose: An analytic method to design excitation and emission filters of a multispectral fluorescence imaging system is proposed and was demonstrated in an application to poultry fecal inspection. Methods: A mathematical model of a multispectral imaging system is proposed and its system parameters, ...

Development of a dielectrophoresis-assisted surface plasmon resonance fluorescence biosensor for detection of bacteria

NASA Astrophysics Data System (ADS)

Kuroda, Chiaki; Iizuka, Ryota; Ohki, Yoshimichi; Fujimaki, Makoto

2018-05-01

To detect biological substances such as bacteria speedily and accurately, a dielectrophoresis-assisted surface plasmon resonance (SPR) fluorescence biosensor is being developed. Using Escherichia coli as a target organism, an appropriate voltage frequency to collect E. coli cells on indium tin oxide quadrupole electrodes by dielectrophoresis is analyzed. Then, E. coli is stained with 4‧,6-diamidino-2-phenylindole (DAPI). To clearly detect fluorescence signals from DAPI-stained E. coli cells, the sensor is optimized so that we can excite SPR on Al electrodes by illuminating 405 nm photons. As a result, the number of fluorescence signals is increased on the electrodes by the application of a low-frequency voltage. This indicates that E. coli cells with a lower permittivity than the surrounding water are collected by negative dielectrophoresis onto the electrodes where the electric field strength is lowest.

A fluorescent sensor based on thioglycolic acid capped cadmium sulfide quantum dots for the determination of dopamine

NASA Astrophysics Data System (ADS)

Kulchat, Sirinan; Boonta, Wissuta; Todee, Apinya; Sianglam, Pradthana; Ngeontae, Wittaya

2018-05-01

A fluorescent sensor based on thioglycolic acid-capped cadmium sulfide quantum dots (TGA-CdS QDs) has been designed for the sensitive and selective detection of dopamine (DA). In the presence of dopamine (DA), the addition of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activates the reaction between the carboxylic group of the TGA and the amino group of dopamine to form an amide bond, quenching the fluorescence of the QDs. The fluorescence intensity of TGA-CdS QDs can be used to sense the presence of dopamine with a limit of detection of 0.68 μM and a working linear range of 1.0-17.5 μM. This sensor system shows great potential application for dopamine detection in dopamine drug samples and for future easy-to-make analytical devices.

Multifunctional Fluorescent-Magnetic Polymeric Colloidal Particles: Preparations and Bioanalytical Applications.

PubMed

Kaewsaneha, Chariya; Tangboriboonrat, Pramuan; Polpanich, Duangporn; Elaissari, Abdelhamid

2015-10-28

Fluorescent-magnetic particles (FMPs) play important roles in modern materials, especially as nanoscale devices in the biomedical field. The interesting features of FMPs are attributed to their dual detection ability, i.e., fluorescent and magnetic modes. Functionalization of FMPs can be performed using several types of polymers, allowing their use in various applications. The synergistic potentials for unique multifunctional, multilevel targeting nanoscale devices as well as combination therapies make them particularly attractive for biomedical applications. However, the synthesis of FMPs is challenging and must be further developed. In this review article, we summarized the most recent representative works on polymer-based FMP systems that have been applied particularly in the bioanalytical field.

One-Step Hydrothermal Approach to Synthesis Carbon Dots from D-Sorbitol for Detection of Iron(III) and Cell Imaging.

PubMed

Zhang, Junqiu; Yan, Juping; Wang, Yingte; Zhang, Yong

2018-07-01

A facile and economic approach to synthesis highly fluorescence carbon dots (CDs) via one-step hydrothermal treatment of D-sorbitol was presented. The as-synthesized CDs were characterized by good water solubility, well monodispersion, and excellent biocompatibility. Spherical CDs had a particle size about 5 nm and exhibited a quantum yield of 8.85% at excitation wavelength of 360 nm. In addition, the CDs can serve as fluorescent probe for sensitive and selective detection of Fe3+ ions with the detection limit of 1.16 μM. Moreover, the potential of the as-prepared carbon dots for biological application was confirmed by employing it for fluorescence imaging in MCF-7 cells.

Fluorescent aromatic sensors and their methods of use

NASA Technical Reports Server (NTRS)

Meador, Michael A. (Inventor); Tyson, Daniel S. (Inventor); Ilan, Ulvi F. (Inventor)

2012-01-01

Aromatic molecules that can be used as sensors are described. The aromatic sensors include a polycyclic aromatic hydrocarbon core with a five-membered imide rings fused to the core and at least two pendant aryl groups. The aromatic sensor molecules can detect target analytes or molecular strain as a result of changes in their fluorescence, in many cases with on-off behavior. Aromatic molecules that fluoresce at various frequencies can be prepared by altering the structure of the aromatic core or the substituents attached to it. The aromatic molecules can be used as sensors for various applications such as, for example, the detection of dangerous chemicals, biomedical diagnosis, and the detection of damage or strain in composite materials. Methods of preparing aromatic sensor molecules are also described.

Arabidopsis thaliana Somatic Embryogenesis Receptor Kinase 1 protein is present in sporophytic and gametophytic cells and undergoes endocytosis.

PubMed

Kwaaitaal, M A C J; de Vries, S C; Russinova, E

2005-10-01

Arabidopsis thaliana plants expressing AtSERK1 fused to yellow-fluorescent protein were generated. Fluorescence was detected predominantly at the cell periphery, most likely the plasma membrane, of cells in ovules, embryo sacs, anthers, and embryos and in seedlings. The AtSERK1 protein was detected in diverse cell types including the epidermis and the vascular bundles. In some cells, fluorescent receptors were seen in small vesicle-like compartments. After application of the fungal toxin Brefeldin A, the fluorescent receptors were rapidly internalized in the root meristem and root vascular tissue. We conclude that the AtSERK1 receptor functions in a common signalling pathway employed in both sporophytic and gametophytic cells.

A highly sensitive and selective off-on fluorescent chemosensor for hydrazine based on coumarin β-diketone

NASA Astrophysics Data System (ADS)

Wu, Wei-Na; Wu, Hao; Wang, Yuan; Mao, Xian-Jie; Zhao, Xiao-Lei; Xu, Zhou-Qing; Fan, Yun-Chang; Xu, Zhi-Hong

2018-01-01

A coumarin-based sensor C1, namely 3-acetoacetylcoumarin was designed, synthesized and applied for hydrazine detection. Hydrazinolysis of the chemosensor gives a fluorescent coumarin-pyrazole product C1 - N2H4 [3-(3-methyl-1H-pyrazol-5-yl)coumarin], and thus resulting in a prominent fluorescence off-on response toward hydrazine under physiological conditions. The probe is highly selective toward hydrazine over cations, anions and other biologically/environmentally abundant analytes. The detection limit of the probe is 3.2 ppb. The sensing mechanism was supported by 1H NMR, IR, MS and DFT calculation. The application of the fluorescent probe in monitoring intracellular hydrazine in glioma cell line U251 was also demonstrated.

Novel online security system based on rare-earth-doped glass microbeads

NASA Astrophysics Data System (ADS)

Officer, Simon; Prabhu, G. R.; Pollard, Pat; Hunter, Catherine; Ross, Gary A.

2004-06-01

A novel fluorescent security label has been produced that could replace numerous conventional fluorescent dyes in document security. This label utilizes rare earth ions doped in a borosilicate glass matrix to produce sharp spectral fluorescence peaks with characteristic long lifetimes due to the rare earth ions. These are subsequently detected by an online detection system based on fluorescence and the long lifetimes to avoid any interference from other fluorophores present in the background. Security is further enhanced by the interaction of the rare earth ions with each other and the effect of the host on the emission spectra and therefore the number of permutations that could be produced. This creates a very secure label with various applications for the security market.

Facile synthesis of Curcuma longa tuber powder engineered metal nanoparticles for bioimaging applications

NASA Astrophysics Data System (ADS)

Sankar, Renu; Rahman, Pattanathu K. S. M.; Varunkumar, Krishnamoorthy; Anusha, Chidambaram; Kalaiarasi, Arunachalam; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

2017-02-01

Nanomaterials based fluorescent agents are rapidly becoming significant and promising transformative tools for improving medical diagnostics for extensive in vivo imaging modalities. Compared with conventional fluorescent agents, nano-fluorescence has capabilities to improve the in vivo detection and enriched targeting efficiencies. In our laboratory we synthesized fluorescent metal nanoparticles of silver, copper and iron using Curcuma longa tuber powder by simple reduction. The physicochemical properties of the synthesized metal nanoparticles were attained using UV-visible spectrophotometry, scanning electron microscopy with EDAX spectroscopy, dynamic light scattering, Fourier-transform infrared spectroscopy and X-ray diffraction. The Curcuma longa tuber powder has one of the bioactive compound Curcumin might act as a capping agent during the synthesis of nanoparticles. The synthesized metal nanoparticles fluorescence property was confirmed by spectrofluorometry. When compared with copper and iron nanoparticles the silver nanoparticles showed high fluorescence intensity under spectrofluorometry. Moreover, in vitro cell images of the silver nanoparticles in A549 cell lines also correlated with the results of spectrofluorometry. These silver nanoparticles show inspiring cell-imaging applications. They enter into cells without any further modifications, and the fluorescence property can be utilized for fluorescence-based cell imaging applications.

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.

PubMed

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.

A new relative referencing method for crop monitoring using chlorophyll fluorescence

NASA Technical Reports Server (NTRS)

Norikane, J.; Goto, E.; Kurata, K.; Takakura, T.

2003-01-01

The measurement of plant chlorophyll fluorescence has been used for many years as a method to monitor a plant's health status. These types of methods have been mostly relegated to the laboratory. The newly developed Relative Referencing Method allows for the measurement of chlorophyll fluorescence under artificial lighting conditions. The fluorescence signal can be determined by first taking a reference signal measurement, then a second measurement with an additional fluorescence excitation source. The first signal can then be subtracted from the second and the plant's chlorophyll fluorescence due to the second lighting source can be determined. With this simple approach, a photosynthesizing plant can be monitored to detect signs of water stress. Using this approach experiments on tomato plants have shown that it was possible to detect water stress, while the plants were continuously illuminated by fluorescent lamps. This method is a promising tool for the remote monitoring of crops grown in a CELSS-type application. Published by Elsevier Science Ltd on behalf of COSPAR.

Advances in on-chip photodetection for applications in miniaturized genetic analysis systems

NASA Astrophysics Data System (ADS)

Namasivayam, Vijay; Lin, Rongsheng; Johnson, Brian; Brahmasandra, Sundaresh; Razzacki, Zafar; Burke, David T.; Burns, Mark A.

2004-01-01

Microfabrication techniques have become increasingly popular in the development of next generation DNA analysis devices. Improved on-chip fluorescence detection systems may have applications in developing portable hand-held instruments for point-of-care diagnostics. Miniaturization of fluorescence detection involves construction of ultra-sensitive photodetectors that can be integrated onto a fluidic platform combined with the appropriate optical emission filters. We have previously demonstrated integration PIN photodiodes onto a microfabricated electrophoresis channel for separation and detection of DNA fragments. In this work, we present an improved detector structure that uses a PINN+ photodiode with an on-chip interference filter and a robust liquid barrier layer. This new design yields high sensitivity (detection limit of 0.9 ng µl-1 of DNA), low-noise (S/N ~ 100/1) and enhanced quantum efficiencies (>80%) over the entire visible spectrum. Applications of these photodiodes in various areas of DNA analysis such as microreactions (PCR), separations (electrophoresis) and microfluidics (drop sensing) are presented.

Molecules for Fluorescence Detection of Specific Chemicals

NASA Technical Reports Server (NTRS)

Fedor, Steve

2008-01-01

A family of fluorescent dye molecules has been developed for use in on-off fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases. A molecule in this family consists of a fluorescent core (such as an anthracene or pyrene) attached to two end groups that, when the dye is excited by absorption of light, transfer an electron to the core, thereby quenching the fluorescence. The end groups can be engineered so that they react chemically with certain analytes. Upon reaction, electrons on the end groups are no longer available for transfer to the core and, consequently, the fluorescence from the core is no longer quenched. The chemoselectivity of these molecules can be changed by changing the end groups. For example, aniline end groups afford a capability for sensing acids or acid halides (including those contained in chemical warfare agents). Pyridine or bipyridyl end groups would enable sensing of metal ions. Other chemicals that can be selectively detected through suitable choice of end groups include glucose and proteins. Moreover, the fluorescent cores can be changed to alter light-absorption and -emission characteristics: anthracene cores fluoresce at wavelengths around 500 nm, whereas perylene cores absorb and emit at wavelengths of about 600 nm.

[Study of the Detecting System of CH4 and SO2 Based on Spectral Absorption Method and UV Fluorescence Method].

PubMed

Wang, Shu-tao; Wang, Zhi-fang; Liu, Ming-hua; Wei, Meng; Chen, Dong-ying; Wang, Xing-long

2016-01-01

According to the spectral absorption characteristics of polluting gases and fluorescence characteristics, a time-division multiplexing detection system is designed. Through this system we can detect Methane (CH4) and sulfur dioxide (SO2) by using spectral absorption method and the SO2 can be detected by using UV fluorescence method. The system consists of four parts: a combination of a light source which could be switched, the common optical path, the air chamber and the signal processing section. The spectral absorption characteristics and fluorescence characteristics are measured first. Then the experiment of detecting CH4 and SO2 through spectral absorption method and the experiment of detecting SO2 through UV fluorescence method are conducted, respectively. Through measuring characteristics of spectral absorption and fluorescence, we get excitation wavelengths of SO2 and CH4 measured by spectral absorption method at the absorption peak are 280 nm and 1.64 μm, respectively, and the optimal excitation wavelength of SO2 measured by UV fluorescence method is 220 nm. we acquire the linear relation between the concentration of CH4 and relative intensity and the linear relation between the concentration of SO2 and output voltage after conducting the experiment of spectral absorption method, and the linearity are 98.7%, 99.2% respectively. Through the experiment of UV fluorescence method we acquire that the relation between the concentration of SO2 and the voltage is linear, and the linearity is 99.5%. Research shows that the system is able to be applied to detect the polluted gas by absorption spectrum method and UV fluorescence method. Combing these two measurement methods decreases the costing and the volume, and this system can also be used to measure the other gases. Such system has a certain value of application.

Titanium Dioxide Nanoparticles (TiO₂) Quenching Based Aptasensing Platform: Application to Ochratoxin A Detection.

PubMed

Sharma, Atul; Hayat, Akhtar; Mishra, Rupesh K; Catanante, Gaëlle; Bhand, Sunil; Marty, Jean Louis

2015-09-22

We demonstrate for the first time, the development of titanium dioxide nanoparticles (TiO₂) quenching based aptasensing platform for detection of target molecules. TiO₂ quench the fluorescence of FAM-labeled aptamer (fluorescein labeled aptamer) upon the non-covalent adsorption of fluorescent labeled aptamer on TiO₂ surface. When OTA interacts with the aptamer, it induced aptamer G-quadruplex complex formation, weakens the interaction between FAM-labeled aptamer and TiO₂, resulting in fluorescence recovery. As a proof of concept, an assay was employed for detection of Ochratoxin A (OTA). At optimized experimental condition, the obtained limit of detection (LOD) was 1.5 nM with a good linearity in the range 1.5 nM to 1.0 µM for OTA. The obtained results showed the high selectivity of assay towards OTA without interference to structurally similar analogue Ochratoxin B (OTB). The developed aptamer assay was evaluated for detection of OTA in beer sample and recoveries were recorded in the range from 94.30%-99.20%. Analytical figures of the merits of the developed aptasensing platform confirmed its applicability to real samples analysis. However, this is a generic aptasensing platform and can be extended for detection of other toxins or target analyte.

Frequency domain fluorescent diffuse tomography of small animals with DsRed2-expressed tumors

NASA Astrophysics Data System (ADS)

Turchin, Ilya V.; Savitsky, Alexander P.; Kamensky, Vladislav A.; Plehanov, Vladimir I.; Orlova, Anna G.; Sergeeva, Ekaterina A.; Kleshnin, Mikhail S.; Shirmanova, Marina V.

2006-02-01

The main applications of fluorescent proteins (FPs) are monitoring tumor growth, angiogenesis, metastases formation and effects of new classes of drugs. Different types of tomography allow fluorescence imaging of tumors located deep in human or animal tissue. These techniques were used for investigation of the distribution of near-infrared fluorescent probes, but only a few works are devoted to fluorescence tomography in visible light. In this work, preliminary results of the frequency domain fluorescent diffuse tomography (FD FDT) method in application to DsRed2 protein as a fluorescent agent are presented. For the first step of our experiments we utilized second harmonic generation of Nd:YAG laser (532 nm) modulated by low frequency (1 kHz) in the experimental setup. The transilluminative planar configuration was used in the setup. A series of model experiments has been conducted and show good agreement between theoretical and experimental fluorescence intensity. Post mortem experiments with capsules containing DsRed2 and scattering solution introduced into esophagus of rats to simulate tumor formation have been conducted. The results of these experiments show that sensitivity of the setup is sufficient to detect DsRed2 in concentrations similar to those in FP-expressed tumor, but the contrast is not enough high to separate fluorescence of DsRed2 and surrounding tissues. The setup can be significantly improved by utilizing high-frequency modulation (110 MHz using acousto-optical modulator) of the excitation light and precise phase measurements due to difference in fluorescence life-time of FPs and surrounding tissues. An algorithm of processing a fluorescent image based on calculating zero of maximum curvature was employed for detection of fluorescent inclusions boundaries in the image.

NIR-induced highly sensitive detection of latent finger-marks by NaYF4:Yb,Er upconversion nanoparticles in a dry powder state

PubMed Central

Wang, Meng; Li, Ming; Yang, Mingying; Zhang, Xiaomei; Yu, Aoyang; Zhu, Ye; Qiu, Penghe; Mao, Chuanbin

2016-01-01

The most commonly found fingermarks at crime scenes are latent and, thus, an efficient method for detecting latent fingermarks is very important. However, traditional developing techniques have drawbacks such as low detection sensitivity, high background interference, complicated operation, and high toxicity. To tackle this challenge, we employed fluorescent NaYF4:Yb,Er upconversion nanoparticles (UCNPs), which can fluoresce visible light when excited by 980 nm human-safe near-infrared light, to stain the latent fingermarks on various substrate surfaces. The UCNPs were successfully used as a novel fluorescent label for the detection of latent fingermarks with high sensitivity, low background, high efficiency, and low toxicity on various substrates including non-infiltrating materials (glass, marble, aluminum alloy sheets, stainless steel sheets, aluminum foils, and plastic cards), semi-infiltrating materials (floor leathers, ceramic tiles, wood floor, and painted wood), and infiltrating materials such as various types of papers. This work shows that UCNPs are a versatile fluorescent label for the facile detection of fingermarks on virtually any material, enabling their practical applications in forensic sciences. PMID:27818741

Multivariate optical element platform for compressed detection of fluorescence markers

NASA Astrophysics Data System (ADS)

Priore, Ryan J.; Swanstrom, Joseph A.

2014-05-01

The success of a commercial fluorescent diagnostic assay is dependent on the selection of a fluorescent biomarker; due to the broad nature of fluorescence biomarker emission profiles, only a small number of fluorescence biomarkers may be discriminated from each other as a function of excitation source. Multivariate Optical Elements (MOEs) are thin-film devices that encode a broad band, spectroscopic pattern allowing a simple broadband detector to generate a highly sensitive and specific detection for a target analyte. MOEs have historically been matched 1:1 to a discrete analyte or class prediction; however, MOE filter sets are capable of sensing projections of the original sparse spectroscopic space enabling a small set of MOEs to discriminate a multitude of target analytes. This optical regression can offer real-time measurements with relatively high signal-to-noise ratios that realize the advantages of multiplexed detection and pattern recognition in a simple optical instrument. The specificity advantage of MOE-based sensors allows fluorescent biomarkers that were once incapable of discrimination from one another via optical band pass filters to be employed in a common assay panel. A simplified MOE-based sensor may ultimately reduce the requirement for highly trained operators as well as move certain life science applications like disease prognostication from the laboratory to the point of care. This presentation will summarize the design and fabrication of compressed detection MOE filter sets for detecting multiple fluorescent biomarkers simultaneously with strong spectroscopic interference as well as comparing the detection performance of the MOE sensor with traditional optical band pass filter methodologies.

Selective detection of Co2+ by fluorescent nano probe: Diagnostic approach for analysis of environmental samples and biological activities

NASA Astrophysics Data System (ADS)

Mahajan, Prasad G.; Dige, Nilam C.; Desai, Netaji K.; Patil, Shivajirao R.; Kondalkar, Vijay V.; Hong, Seong-Karp; Lee, Ki Hwan

2018-06-01

Nowadays scientist over the world are engaging to put forth improved methods to detect metal ion in an aqueous medium based on fluorescence studies. A simple, selective and sensitive method was proposed for detection of Co2+ ion using fluorescent organic nanoparticles. We synthesized a fluorescent small molecule viz. 4,4‧-{benzene-1,4-diylbis-[(Z)methylylidenenitrilo]}dibenzoic acid (BMBA) to explore its suitability as sensor for Co2+ ion and biocompatibility in form of nanoparticles. Fluorescence nanoparticles (BMBANPs) prepared by simple reprecipitation method. Aggregation induced enhanced emission of BMBANPs exhibits the narrower particle size of 68 nm and sphere shape morphology. The selective fluorescence quenching was observed by addition of Co2+ and does not affected by presence of other coexisting ion solutions. The photo-physical properties, viz. UV-absorption, fluorescence emission, and lifetime measurements are in support of ligand-metal interaction followed by static fluorescence quenching phenomenon in emission of BMBANPs. Finally, we develop a simple analytical method for selective and sensitive determination of Co2+ ion in environmental samples. The cell culture E. coli, Bacillus sps., and M. tuberculosis H37RV strain in the vicinity of BMBANPs indicates virtuous anti-bacterial and anti-tuberculosis activity which is of additional novel application shown by prepared nanoparticles.

Synergistic electron transfer effect-based signal amplification strategy for the ultrasensitive detection of dopamine.

PubMed

Lu, Qiujun; Chen, Xiaogen; Liu, Dan; Wu, Cuiyan; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

2018-05-15

The selective and sensitive detection of dopamine (DA) is of great significance for the identification of schizophrenia, Huntington's disease, and Parkinson's disease from the perspective of molecular diagnostics. So far, most of DA fluorescence sensors are based on the electron transfer from the fluorescence nanomaterials to DA-quinone. However, the limited electron transfer ability of the DA-quinone affects the level of detection sensitivity of these sensors. In this work, based on the DA can reduce Ag + into AgNPs followed by oxidized to DA-quinone, we developed a novel silicon nanoparticles-based electron transfer fluorescent sensor for the detection of DA. As electron transfer acceptor, the AgNPs and DA-quinone can quench the fluorescence of silicon nanoparticles effectively through the synergistic electron transfer effect. Compared with traditional fluorescence DA sensors, the proposed synergistic electron transfer-based sensor improves the detection sensitivity to a great extent (at least 10-fold improvement). The proposed sensor shows a low detection limit of DA, which is as low as 0.1 nM under the optimal conditions. This sensor has potential applicability for the detection of DA in practical sample. This work has been demonstrated to contribute to a substantial improvement in the sensitivity of the sensors. It also gives new insight into design electron transfer-based sensors. Copyright © 2018. Published by Elsevier B.V.

Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Hui

2001-01-01

Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitablymore » designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm 2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection.« less

Double-labeled donor probe can enhance the signal of fluorescence resonance energy transfer (FRET) in detection of nucleic acid hybridization

PubMed Central

Okamura, Yukio; Kondo, Satoshi; Sase, Ichiro; Suga, Takayuki; Mise, Kazuyuki; Furusawa, Iwao; Kawakami, Shigeki; Watanabe, Yuichiro

2000-01-01

A set of fluorescently-labeled DNA probes that hybridize with the target RNA and produce fluorescence resonance energy transfer (FRET) signals can be utilized for the detection of specific RNA. We have developed probe sets to detect and discriminate single-strand RNA molecules of plant viral genome, and sought a method to improve the FRET signals to handle in vivo applications. Consequently, we found that a double-labeled donor probe labeled with Bodipy dye yielded a remarkable increase in fluorescence intensity compared to a single-labeled donor probe used in an ordinary FRET. This double-labeled donor system can be easily applied to improve various FRET probes since the dependence upon sequence and label position in enhancement is not as strict. Furthermore this method could be applied to other nucleic acid substances, such as oligo RNA and phosphorothioate oligonucleotides (S-oligos) to enhance FRET signal. Although the double-labeled donor probes labeled with a variety of fluorophores had unexpected properties (strange UV-visible absorption spectra, decrease of intensity and decay of donor fluorescence) compared with single-labeled ones, they had no relation to FRET enhancement. This signal amplification mechanism cannot be explained simply based on our current results and knowledge of FRET. Yet it is possible to utilize this double-labeled donor system in various applications of FRET as a simple signal-enhancement method. PMID:11121494

Detection of endogenous alkaline phosphatase activity in intact cells by flow cytometry using the fluorogenic ELF-97 phosphatase substrate

NASA Technical Reports Server (NTRS)

Telford, W. G.; Cox, W. G.; Stiner, D.; Singer, V. L.; Doty, S. B.

1999-01-01

BACKGROUND: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry. METHODS: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry. RESULTS: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method. CONCLUSIONS: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications. Copyright 1999 Wiley-Liss, Inc.

Sensing and enumerating rare circulating cells with diffuse light

NASA Astrophysics Data System (ADS)

Zettergren, Eric; Vickers, Dwayne; Niedre, Mark

2011-02-01

Detection and quantification of circulating cells in live animals is a challenging and important problem in many areas of biomedical research. Current methods involve extraction of blood samples and counting of cells ex-vivo. Since only small blood volumes are analyzed at specific time points, monitoring of changes in cell populations over time is difficult and rare cells often escape detection. The goal of this research is to develop a method for enumerating very rare circulating cells in the bloodstream non-invasively. This would have many applications in biomedical research, including monitoring of cancer metastasis and tracking of hematopoietic stem cells. In this work we describe the optical configuration of our instrument which allows fluorescence detection of single cells in diffusive media at the mesoscopic scale. Our instrument design consists of two continuous wave laser diode sources and an 8-channel fiber coupled multi-anode photon counting PMT. Fluorescence detector fibers were arranged circularly around the target in a miniaturized ring configuration. Cell-simulating fluorescent microspheres and fluorescently-labeled cells were passed through a limb mimicking phantom with similar optical properties and background fluorescence as a limb of a mouse. Our data shows that we are able to successfully detect and count these with high quantitative accuracy. Future work includes characterization of our instrument using fluorescently labeled cells in-vivo. If successful, this technique would allow several orders of magnitude in vivo detection sensitivity improvement versus current approaches.

Frequency-domain photoacoustic and fluorescence microscopy: application on labeled and unlabeled cells

NASA Astrophysics Data System (ADS)

Langer, Gregor; Buchegger, Bianca; Jacak, Jaroslaw; Pfeffer, Karoline; Wohlfarth, Sven; Hannesschläger, Günther; Klar, Thomas A.; Berer, Thomas

2018-02-01

In this paper, multimodal optical-resolution frequency-domain photoacoustic and fluorescence scanning microscopy is presented on labeled and unlabeled cells. In many molecules, excited electrons relax radiatively and non-radiatively, leading to fluorescence and photoacoustic signals, respectively. Both signals can then be detected simultaneously. There also exist molecules, e.g. hemoglobin, which do not exhibit fluorescence, but provide photoacoustic signals solely. Other molecules, especially fluorescent dyes, preferentially exhibit fluorescence. The fluorescence quantum yield of a molecule and with it the strength of photoacoustic and fluorescence signals depends on the local environment, e.g. on the pH. Therefore, the local distribution of the simultaneously recorded photoacoustic and fluorescence signals may be used in order to obtain information about the local chemistry.

Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Hui

2001-01-01

Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, the author introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties ofmore » suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, they demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm 2 for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection. In the second part of this dissertation, the author used laser-induced native fluorescence coupled with capillary electrophoresis (LINF-CE) and microscope imaging to study the single cell degranulation. On the basis of good temporal correlation with events observed through an optical microscope, they have identified individual peaks in the fluorescence electropherograms as serotonin released from the granular core on contact with the surrounding fluid.« less

On the uncertainty in single molecule fluorescent lifetime and energy emission measurements

NASA Technical Reports Server (NTRS)

Brown, Emery N.; Zhang, Zhenhua; Mccollom, Alex D.

1995-01-01

Time-correlated single photon counting has recently been combined with mode-locked picosecond pulsed excitation to measure the fluorescent lifetimes and energy emissions of single molecules in a flow stream. Maximum likelihood (ML) and least square methods agree and are optimal when the number of detected photons is large however, in single molecule fluorescence experiments the number of detected photons can be less than 20, 67% of those can be noise and the detection time is restricted to 10 nanoseconds. Under the assumption that the photon signal and background noise are two independent inhomogeneous poisson processes, we derive the exact joint arrival time probably density of the photons collected in a single counting experiment performed in the presence of background noise. The model obviates the need to bin experimental data for analysis, and makes it possible to analyze formally the effect of background noise on the photon detection experiment using both ML or Bayesian methods. For both methods we derive the joint and marginal probability densities of the fluorescent lifetime and fluorescent emission. the ML and Bayesian methods are compared in an analysis of simulated single molecule fluorescence experiments of Rhodamine 110 using different combinations of expected background nose and expected fluorescence emission. While both the ML or Bayesian procedures perform well for analyzing fluorescence emissions, the Bayesian methods provide more realistic measures of uncertainty in the fluorescent lifetimes. The Bayesian methods would be especially useful for measuring uncertainty in fluorescent lifetime estimates in current single molecule flow stream experiments where the expected fluorescence emission is low. Both the ML and Bayesian algorithms can be automated for applications in molecular biology.

On the Uncertainty in Single Molecule Fluorescent Lifetime and Energy Emission Measurements

NASA Technical Reports Server (NTRS)

Brown, Emery N.; Zhang, Zhenhua; McCollom, Alex D.

1996-01-01

Time-correlated single photon counting has recently been combined with mode-locked picosecond pulsed excitation to measure the fluorescent lifetimes and energy emissions of single molecules in a flow stream. Maximum likelihood (ML) and least squares methods agree and are optimal when the number of detected photons is large, however, in single molecule fluorescence experiments the number of detected photons can be less than 20, 67 percent of those can be noise, and the detection time is restricted to 10 nanoseconds. Under the assumption that the photon signal and background noise are two independent inhomogeneous Poisson processes, we derive the exact joint arrival time probability density of the photons collected in a single counting experiment performed in the presence of background noise. The model obviates the need to bin experimental data for analysis, and makes it possible to analyze formally the effect of background noise on the photon detection experiment using both ML or Bayesian methods. For both methods we derive the joint and marginal probability densities of the fluorescent lifetime and fluorescent emission. The ML and Bayesian methods are compared in an analysis of simulated single molecule fluorescence experiments of Rhodamine 110 using different combinations of expected background noise and expected fluorescence emission. While both the ML or Bayesian procedures perform well for analyzing fluorescence emissions, the Bayesian methods provide more realistic measures of uncertainty in the fluorescent lifetimes. The Bayesian methods would be especially useful for measuring uncertainty in fluorescent lifetime estimates in current single molecule flow stream experiments where the expected fluorescence emission is low. Both the ML and Bayesian algorithms can be automated for applications in molecular biology.

Challenges in paper-based fluorogenic optical sensing with smartphones

NASA Astrophysics Data System (ADS)

Ulep, Tiffany-Heather; Yoon, Jeong-Yeol

2018-05-01

Application of optically superior, tunable fluorescent nanotechnologies have long been demonstrated throughout many chemical and biological sensing applications. Combined with microfluidics technologies, i.e. on lab-on-a-chip platforms, such fluorescent nanotechnologies have often enabled extreme sensitivity, sometimes down to single molecule level. Within recent years there has been a peak interest in translating fluorescent nanotechnology onto paper-based platforms for chemical and biological sensing, as a simple, low-cost, disposable alternative to conventional silicone-based microfluidic substrates. On the other hand, smartphone integration as an optical detection system as well as user interface and data processing component has been widely attempted, serving as a gateway to on-board quantitative processing, enhanced mobility, and interconnectivity with informational networks. Smartphone sensing can be integrated to these paper-based fluorogenic assays towards demonstrating extreme sensitivity as well as ease-of-use and low-cost. However, with these emerging technologies there are always technical limitations that must be addressed; for example, paper's autofluorescence that perturbs fluorogenic sensing; smartphone flash's limitations in fluorescent excitation; smartphone camera's limitations in detecting narrow-band fluorescent emission, etc. In this review, physical optical setups, digital enhancement algorithms, and various fluorescent measurement techniques are discussed and pinpointed as areas of opportunities to further improve paper-based fluorogenic optical sensing with smartphones.

Fluorescence alteration of MPA capped CdSe quantum dots by spontaneous biomarker protein adsorption.

PubMed

Rowley, Amber; Parks, Tegan; Parks, Kaden; Medley, Kyle; Cordner, Alex; Yu, Ming

2018-05-23

Quantum dots (QDs) have significant potentials in biomedical applications of bioimaging and biosensing. Spontaneous adsorption of proteins on QDs surface is a common phenomenon, which occurred to serum proteins in biological samples, and has been observed to enhance QDs fluorescence. In this study, fluorescence alteration of 3-mercaptopropionic acid (MPA) capped CdSe quantum dots by four individual biomarker proteins was investigated. By monitoring the fluorescence emission of QDs, the biomarker protein adsorbed spontaneously on QDs surface was recognized and quantified. When alpha fetoprotein (AFP) or heat shock protein 90 alpha (HSP90α) were present, the QDs became brighter. The presence of cytochrome C (CytoC) or lysozyme (Lyz) made the QDs dimmer first, and then brighter. Within 5 min response time all four biomarker proteins were detected individually with the estimated detection limit in the range of 1-10 ng/mL and good linear dynamic ranges. The results suggested that the fluorescence of QDs was responsive to not only serum proteins but also biomarker proteins. The fluorescence response was able to correlate quantitatively with the amount of biomarker proteins in relatively low concentrations. These results provide more information to understand QDs and support their applications in biomedical fields. Copyright © 2018. Published by Elsevier Inc.

Coordination ability determined transition metal ions substitution of Tb in Tb-Asp fluorescent nanocrystals and a facile ions-detection approach.

PubMed

Duan, Jiazhi; Ma, Baojin; Liu, Feng; Zhang, Shan; Wang, Shicai; Kong, Ying; Du, Min; Han, Lin; Wang, Jianjun; Sang, Yuanhua; Liu, Hong

2018-04-26

Although the synthesis and fluorescent properties of lanthanide-amino acid complex nanostructures have been investigated extensively, limited studies have been reported on metal ions' substitution ability for the lanthanide ions in the complex and their effect on the fluorescent property. In this study, taking biocompatible Tb-aspartic acid (Tb-Asp) complex nanocrystals as a model, the substitution mechanism of metal ions, particularly transition metals, for Tb ions in Tb-Asp nanocrystals and the change in the fluorescent property of the Tb-Asp nanocrystals after substitution were systematically investigated. The experimental results illustrated that metal ions with higher electronegativity, higher valence, and smaller radius possess stronger ability for Tb ions' substitution in Tb-Asp nanocrystals. Based on the effect of substituting ions' concentration on the fluorescent property of Tb-Asp, a facile method for copper ions detection with high sensitivity was proposed by measuring the fluorescent intensity of Tb-Asp nanocrystals' suspensions containing different concentrations of copper ions. The good biocompatibility, great convenience of synthesis and sensitive detection ability make Tb-Asp nanocrystals a very low cost and effective material for metal ions detection, which also opens a new door for practical applications of metal-Asp coordinated nanocrystals.

A highly sensitive protocol for microscopy of alkyne lipids and fluorescently tagged or immunostained proteins[S

PubMed Central

Gaebler, Anne; Penno, Anke; Kuerschner, Lars; Thiele, Christoph

2016-01-01

The demand to study the cellular localization of specific lipids has led to recent advances in lipid probes and microscopy. Alkyne lipids bear a small, noninterfering tag and can be detected upon click reaction with an azide-coupled reporter. Fluorescent alkyne lipid imaging crucially depends on appropriate azide reporters and labeling protocols that allow for an efficient click reaction and therefore a sensitive detection. We synthesized several azide reporters with different spacer components and tested their suitability for alkyne lipid imaging in fixed cells. The implementation of a copper-chelating picolyl moiety into fluorescent or biotin-based azide reagents strongly increased the sensitivity of the imaging routine. We demonstrate the applicability and evaluate the performance of this approach using different lipid classes and experimental setups. As azide picolyl reporters allow for reduced copper catalyst concentrations, they also enable coimaging of alkyne lipids with multiple fluorescent proteins including enhanced green fluorescent protein. Alternatively, and as we also show, microscopy of alkyne lipids can be combined with protein detection by immunocytochemistry. In summary, we present a robust, sensitive, and highly versatile protocol for the labeling of alkyne lipids with azide-coupled reporters for fluorescence microscopy that can be combined with different protein detection and imaging techniques. PMID:27565170

Carbon dots-based fluorescent probe for "off-on" sensing of Hg(II) and I⁻.

PubMed

He, Jiangling; Zhang, Haoran; Zou, Jinliang; Liu, Yingliang; Zhuang, Jianle; Xiao, Yong; Lei, Bingfu

2016-05-15

Herein, we report a simple, one-step reflux method for synthesis of photoluminescent carbon dots (CDs) using citric acid as the carbon source and diethylenetriamine (DETA) as the surface passivation reagent along with a high quantum yield (82.40%), the fluorescence intensity of the CDs was found to be effectively quenched by Hg(II) ions. Upon addition of I(-) to the CDs/Hg(II) complex dispersion, the fluorescence intensity of the CDs was significantly recovered. Furthermore, we developed an "off-on" fluorescence assay for the detection of I(-) using CDs/Hg(II) as a fluorescence probe. This probe enables the selective detection of Hg(II) with a linear range of 0-80 μM and a limit of detection is 0.201 µM and a limit of detection about I(-) is 0.234 µM with a linear range of 0-70 μM. Most importantly, the sensors can be successfully applied to the determination of Hg(II) and I(-) in real lake water and urine of cattles, the "off-on" sensor demonstrates high selectivity, repeatability, stability, which offer this CDs-based "off-on" fluorescent sensor a promising platform for environmental and biological sensing applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A cationic conjugated polymer and graphene oxide: Application to amplified fluorescence detection of sinapine.

PubMed

Zhang, Zhen; Xiang, Xia; Shi, Jianbin; Huang, Fenghong; Xia, Xiaoyang; Zheng, Mingming; Han, Ling; Tang, Hu

2018-10-05

An amplified fluorescence strategy is described for the detection of sinapine (SP) by using a cationic conjugated polymer (PFP) and graphene oxide (GO). It is observed that the fluorescein (FAM)-labeled single-stranded DNA (FAM-DNA) is absorbed on the surface of GO if SP is absent. This causes that fluorescence resonance energy transfer (FRET) from PFP to FAM is inefficient when adding PFP into FAM-DNA/GO complex. If SP is added to FAM-DNA/GO complex, FAM-DNA is desorbed from GO surface due to the competitive binding of SP and FAM-DNA toward GO. In this case, FAM-DNA is close to PFP in the presence of PFP through strong electrostatic interaction, leading to the occurrence of efficient FRET. Based on the above phenomenon, we demonstrate a method to amplify fluorescence signal of traditional GO-based SP assay by introducing PFP. In comparison to the use of single GO, the combination of PFP with GO-based strategy displays high turn-on ratio and enhanced sensitivity with a limit of detection as low as 7.3 ng mL -1 for SP detection. Satisfactory results in practical samples are also obtained by the recovery experiments, demonstrating the potential application of cationic conjugated polymer in plant-derived small molecule. Copyright © 2018 Elsevier B.V. All rights reserved.

Selective and sensitive fluorescent sensor for Pd2+ using coumarin 460 for real-time and biological applications.

PubMed

Ashwin, Bosco Christin Maria Arputham; Sivaraman, Gandhi; Stalin, Thambusamy; Yuvakkumar, Rathinam; Muthu Mareeswaran, Paulpandian

2018-06-01

The efficient fluorescent property of coumarin 460 (C460) is utilized to sense the Pd 2+ selectively and sensitively. Fabrication of a sensor strip using commercial adhesive tape is achieved and the detection of Pd 2+ is attempted using a handy UV torch. The naked eye detection in solution state using UV chamber is also attempted. The calculated high binding constant values support the strong stable complex formation of Pd 2+ with C460. The detection limit up to 2.5 × 10 -7  M is achieved using fluorescence spectrometer, which is considerably low from the WHO's recommendation. The response of coumarin 460 with various cations also studied. The quenching is further studied by the lifetime measurements. The binding mechanism is clearly explained by the 1 H NMR titration. The sensing mechanism is established as ICT. C460 strip's Pd 2+ quenching detection is further confirmed by solid-state PL study. The in-vitro response of Pd 2+ in a living cell is also studied using fluorescent imaging studies by means of HeLa cell lines and this probe is very compatible with biological environments. It could be applicable to sense trace amounts of a Pd 2+ ion from various industries. Compared with previous reports, this one is very cheap, sensitive, selective and suitable for biological systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Towards a disposable in vivo miniature implantable fluorescence detector

NASA Astrophysics Data System (ADS)

Bellis, Stephen; Jackson, J. Carlton; Mathewson, Alan

2006-02-01

In the field of fluorescent microscopy, neuronal activity, diabetes and drug treatment are a few of the wide ranging biomedical applications that can be monitored with the use of dye markers. Historically, in-vivo fluorescent detectors consist of implantable probes coupled by optical fibre to sophisticated bench-top instrumentation. These systems typically use laser light to excite the fluorescent marker dies and using sensors, such as the photo-multiplier tube (PMT) or charge coupled devices (CCD), detect the fluorescent light that is filtered from the total excitation. Such systems are large and expensive. In this paper we highlight the first steps toward a fully implantable in-vivo fluorescence detection system. The aim is to make the detector system small, low cost and disposable. The current prototype is a hybrid platform consisting of a vertical cavity surface emitting laser (VCSEL) to provide the excitation and a filtered solid state Geiger mode avalanche photo-diode (APD) to detect the emitted fluorescence. Fluorescence detection requires measurement of extremely low levels of light so the proposed APD detectors combine the ability to count individual photons with the added advantage of being small in size. At present the exciter and sensor are mounted on a hybrid PCB inside a 3mm diameter glass tube.This is wired to external electronics, which provide quenching, photon counting and a PC interface. In this configuration, the set-up can be used for in-vitro experimentation and in-vivo analysis conducted on animals such as mice.

Quantitative performance characterization of three-dimensional noncontact fluorescence molecular tomography

NASA Astrophysics Data System (ADS)

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.

Novel Fluorescent Microemulsion: Probing Properties, Investigating Mechanism, and Unveiling Potential Application.

PubMed

Hou, Mengna; Dang, Leping; Liu, Tiankuo; Guo, Yun; Wang, Zhanzhong

2017-08-09

Nanoscale microemulsions have been utilized as delivery carriers for nutraceuticals and active biological drugs. Herein, we designed and synthesized a novel oil in water (O/W) fluorescent microemulsion based on isoamyl acetate, polyoxyethylene castor oil EL (CrEL), and water. The microemulsion emitted bright blue fluorescence, thus exhibiting its potential for active drug detection with label-free strategy. The microemulsion exhibited excitation-dependent emission and distinct red shift with longer excitation wavelengths. Lifetime and quantum yield of fluorescent microemulsion were 2.831 ns and 5.0%, respectively. An excellent fluorescent stability of the microemulsion was confirmed by altering pH, ionic strength, temperature, and time. Moreover, we proposed a probable mechanism of fluorochromic phenomenon, in connection with the aromatic ring structure of polyoxyethylene ether substituent in CrEL. Based on our findings, we concluded that this new fluorescent microemulsion is a promising drug carrier that can facilitate active drug detection with a label-free strategy. Although further research is required to understand the exact mechanism behind its fluorescence property, this work provided valuable guidance to develop new biosensors based on fluorescent microemulsion.

Exploiting the synergistic effect of concurrent data signals: Low-level fusion of liquid chromatographic with dual detection data.

PubMed

Teglia, Carla M; Azcarate, Silvana M; Alcaráz, Mirta R; Goicoechea, Héctor C; Culzoni, María J

2018-08-15

A low-level data fusion strategy was developed and implemented for data processing of second-order liquid chromatographic data with dual detection, i.e. absorbance and fluorescence monitoring. The synergistic effect of coupling individual information provided by two different detectors was evaluated by analyzing the results gathered after the application of a series of data preprocessing steps and chemometric resolution. The chemometric modeling involved data analysis by MCR-ALS, PARAFAC and N-PLS. Their ability to handle the new data block was assessed through the estimation of the analytical figures of merits achieved in the prediction of a validation set containing fifteen fluorescent and non-fluorescent veterinary active ingredients that can be found in poultry litter. Eventually, the feasibility of the application of the fusion strategy to real poultry litter samples containing the studied compounds was verified. Copyright © 2018 Elsevier B.V. All rights reserved.

Detection of Subclinical Arthritis in Mice by a Thrombin Receptor-Derived Imaging Agent.

PubMed

Friedman, Beth; Whitney, Michael A; Savariar, Elamprakash N; Caneda, Christa; Steinbach, Paul; Xiong, Qing; Hingorani, Dina V; Crisp, Jessica; Adams, Stephen R; Kenner, Michael; Lippert, Csilla N; Nguyen, Quyen T; Guma, Monica; Tsien, Roger Y; Corr, Maripat

2018-01-01

Functional imaging of synovitis could improve both early detection of rheumatoid arthritis (RA) and long-term outcomes. Given the intersection of inflammation with coagulation protease activation, this study was undertaken to examine coagulation protease activities in arthritic mice with a dual-fluorescence ratiometric activatable cell-penetrating peptide (RACPP) that has a linker, norleucine (Nle)-TPRSFL, with a cleavage site for thrombin. K/BxN-transgenic mice with chronic arthritis and mice with day 1 passive serum-transfer arthritis were imaged in vivo for Cy5:Cy7 emission ratiometric fluorescence from proteolytic cleavage and activation of RACPP NleTPRSFL . Joint thickness in mice with serum-transfer arthritis was measured from days 0 to 10. The cleavage-evoked release of Cy5-tagged tissue-adhesive fragments enabled microscopic correlation with immunohistochemistry for inflammatory markers. Thrombin dependence of ratiometric fluorescence was tested by ex vivo application of RACPP NleTPRSFL and argatroban to cryosections obtained from mouse hind paws on day 1 of serum-transfer arthritis. In chronic arthritis, RACPP NleTPRSFL fluorescence ratios of Cy5:Cy7 emission were significantly higher in diseased swollen ankles of K/BxN-transgenic mice than in normal mouse ankles. A high ratio of RACPP NleTPRSFL fluorescence in mouse ankles and toes on day 1 of serum-transfer arthritis correlated with subsequent joint swelling. Foci of high ratiometric fluorescence localized to inflammation, as demarcated by immune reactivity for citrullinated histones, macrophages, mast cells, and neutrophils, in soft tissue on day 1 of serum-transfer arthritis. Ex vivo application of RACPP NleTPRSFL to cryosections obtained from mice on day 1 of serum-transfer arthritis produced ratiometric fluorescence that was inhibited by argatroban. RACPP NleTPRSFL activation detects established experimental arthritis, and the detection of inflammation by RACPP NleTPRSFL on day 1 of serum-transfer arthritis correlates with disease progression. © 2017, American College of Rheumatology.

Solid surface fluorescence immunosensor for ultrasensitive detection of hepatitis B virus surface antigen using PAMAM/CdTe@CdS QDs nanoclusters.

PubMed

Babamiri, Bahareh; Hallaj, Rahman; Salimi, Abdollah

2018-06-20

In the present study, we constructed an ultrasensitive solid surface fluorescence-immunosensor based on highly luminescent CdTe@CdS-PAMAM structures as nanoprobe for determination of HBsAg by monitoring fluorescence intensity. This strategy was achieved by using PAMAM as a signal amplifier; the PAMAM dendrimer with the many functional amine groups can amplify the fluorescence signal of QDs by covalent attachment of CdTe@CdS on PAMAM and hence, improve the sensitivity of the proposed method significantly. A sandwich type immunosensor was formed after the addition of HBsAg and the PAMAM-QD-Ab 2 , respectively. Under optimal conditions, the designed immunosensor demonstrates a good analytical performance for the HBsAg detection in an excellent linear range from 5 fg ml -1 to 0.15 ng ml -1 with the detection limit (LOD) of 0.6 fg ml -1 at a S/N ratio of 3. In addition, the analysis of human serum samples shows that the fluorescent immunoassay has the great potential for early diagnosis of hepatitis B and can be used for the detection of other tumor markers in clinical applications.

Modular fluorescence complementation sensors for live cell detection of epigenetic signals at endogenous genomic sites.

PubMed

Lungu, Cristiana; Pinter, Sabine; Broche, Julian; Rathert, Philipp; Jeltsch, Albert

2017-09-21

Investigation of the fundamental role of epigenetic processes requires methods for the locus-specific detection of epigenetic modifications in living cells. Here, we address this urgent demand by developing four modular fluorescence complementation-based epigenetic biosensors for live-cell microscopy applications. These tools combine engineered DNA-binding proteins with domains recognizing defined epigenetic marks, both fused to non-fluorescent fragments of a fluorescent protein. The presence of the epigenetic mark at the target DNA sequence leads to the reconstitution of a functional fluorophore. With this approach, we could for the first time directly detect DNA methylation and histone 3 lysine 9 trimethylation at endogenous genomic sites in live cells and follow dynamic changes in these marks upon drug treatment, induction of epigenetic enzymes and during the cell cycle. We anticipate that this versatile technology will improve our understanding of how specific epigenetic signatures are set, erased and maintained during embryonic development or disease onset.Tools for imaging epigenetic modifications can shed light on the regulation of epigenetic processes. Here, the authors present a fluorescence complementation approach for detection of DNA and histone methylation at endogenous genomic sites allowing following of dynamic changes of these marks by live-cell microscopy.

Zinc Oxide Nanomaterials for Biomedical Fluorescence Detection

PubMed Central

Hahm, Jong-in

2014-01-01

One-dimensional zinc oxide nanomaterials have been recently developed into novel, extremely effective, optical signal-enhancing bioplatforms. Their usefulness has been demonstrated in various biomedical fluorescence assays. Fluorescence is extensively used in biology and medicine as a sensitive and noninvasive detection method for tracking and analyzing biological molecules. Achieving high sensitivity via improving signal-to-noise ratio is of paramount importance in fluorescence-based, trace-level detection. Recent advances in the development of optically superior one-dimensional materials have contributed to this important biomedical area of detection. This review article will discuss major research developments that have so far been made in this emerging and exciting topical field. The discussion will cover a broad range of subjects including synthesis of zinc oxide nanorods (ZnO NRs), various properties differentiating them as suitable optical biodetection platforms, their demonstrated applicability in DNA and protein detection, and the nanomaterial characteristics relevant for biomolecular fluorescence enhancement. This review will then summarize the current status of ZnO NR-based biodetection and further elaborate future utility of ZnO NR platforms for advanced biomedical assays, based on their proven advantages. Lastly, present challenges experienced in this topical area will be identified and focal subject areas for future research will be suggested as well. PMID:24730276

Highly sensitive and selective detection of dopamine using one-pot synthesized highly photoluminescent silicon nanoparticles.

PubMed

Zhang, Xiaodong; Chen, Xiaokai; Kai, Siqi; Wang, Hong-Yin; Yang, Jingjing; Wu, Fu-Gen; Chen, Zhan

2015-03-17

A simple and highly efficient method for dopamine (DA) detection using water-soluble silicon nanoparticles (SiNPs) was reported. The SiNPs with a high quantum yield of 23.6% were synthesized by using a one-pot microwave-assisted method. The fluorescence quenching capability of a variety of molecules on the synthesized SiNPs has been tested; only DA molecules were found to be able to quench the fluorescence of these SiNPs effectively. Therefore, such a quenching effect can be used to selectively detect DA. All other molecules tested have little interference with the dopamine detection, including ascorbic acid, which commonly exists in cells and can possibly affect the dopamine detection. The ratio of the fluorescence intensity difference between the quenched and unquenched cases versus the fluorescence intensity without quenching (ΔI/I) was observed to be linearly proportional to the DA analyte concentration in the range from 0.005 to 10.0 μM, with a detection limit of 0.3 nM (S/N = 3). To the best of our knowledge, this is the lowest limit for DA detection reported so far. The mechanism of fluorescence quenching is attributed to the energy transfer from the SiNPs to the oxidized dopamine molecules through Förster resonance energy transfer. The reported method of SiNP synthesis is very simple and cheap, making the above sensitive and selective DA detection approach using SiNPs practical for many applications.

Simultaneous fluorescent detection of multiple metal ions based on the DNAzymes and graphene oxide.

PubMed

Yun, Wen; Wu, Hong; Liu, Xingyan; Fu, Min; Jiang, Jiaolai; Du, Yunfeng; Yang, Lizhu; Huang, Yu

2017-09-15

A novel fluorescent detection strategy for simultaneous detection of Cu 2+ , Pb 2+ and Mg 2+ based on DNAzyme branched junction structure with three kinds of DNAzymes and graphene oxide (GO) was presented. Three fluorophores labeled DNA sequences consisted with enzyme-strand (E-DNA) and substrate strand (S-DNA) were annealed to form DNAzyme branched junction structure. In the presence of target metal ion, the DNAzyme was activated to cleave the fluorophore labeled S-DNA. The S-DNA fragments were released and adsorbed onto GO surface to quench the fluorescent signal. The detection limit was calculated to be 1 nM for Cu 2+ , 200 nM for Mg 2+ , and 0.3 nM for Pb 2+ , respectively. This strategy was successfully used for simultaneous detection of Cu 2+ , Mg 2+ and Pb 2+ in human serum. Moreover, it had potential application for simultaneous detection of multiple metal ions in environmental and biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel fluorescein-based "turn-on" probe for the detection of hydrazine and its application in living cells

NASA Astrophysics Data System (ADS)

Xu, Wen-Zhi; Liu, Wei-Yan; Zhou, Ting-Ting; Yang, Yu-Tao; Li, Wei

2018-03-01

We constructed a novel probe for hydrazine detection based on ICT and PET mechanism. Phthalimide and acetyl ester groups were used as the recognition units. Addition of hydrazine produced a turn-on fluorescence at 525 nm along with the fluorescent color change from dark to yellow. The probe could selectively detect hydrazine over other related interfering species. The detection limit of the probe for hydrazine was calculated to be 0.057 μM which was lower than the EPA standard (0.320 μM). Furthermore, the probe could also be applied for the imaging of hydrazine in living cells.

Quantitative evaluation of cross correlation between two finite-length time series with applications to single-molecule FRET.

PubMed

Hanson, Jeffery A; Yang, Haw

2008-11-06

The statistical properties of the cross correlation between two time series has been studied. An analytical expression for the cross correlation function's variance has been derived. On the basis of these results, a statistically robust method has been proposed to detect the existence and determine the direction of cross correlation between two time series. The proposed method has been characterized by computer simulations. Applications to single-molecule fluorescence spectroscopy are discussed. The results may also find immediate applications in fluorescence correlation spectroscopy (FCS) and its variants.

An Enzyme-Responsive "Turn-on" Fluorescence Polymeric Superamphiphile as a Potential Visualizable Phosphate Prodrug Delivery Vehicle.

PubMed

Yang, Xi; Shen, Shihong; Guo, Li; Tan, Jidong; Lei, Henxin; Wu, Jianghan; Zhao, Lei; Xiong, Tao; Wu, Youshen; Cheng, Yilong; Zhang, Yanfeng

2018-06-01

The development of inexpensive and highly efficient enzyme-responsive polymers has significantly contributed to targeted drug delivery systems. Here, a superamphiphile with a capability of fluorescent dissociation sensing is designed. It is constructed with negatively charged adenosine 5'-triphosphate (ATP) and negatively charged fluorescein diphosphate (FDP), which are used as fluorescence detection, and a cationic diblock copolymer methoxy-poly(ethylene glycol) 113 -b-poly(2-dimethyl-aminoethyl methacrylate) 70 . Upon addition of calf intestinal alkaline phosphatase, the superamphiphile disintegrates, presumably due to the enzymatic hydrolysis of ATP. This process is accompanied by an increase in the fluorescence emission intensity of fluorescein owing to the hydrolysis of FDP. The in vitro application of the superamphiphile is also proven. Thus, the "turn-on" fluorescence of the superamphiphile serves as a real-time module for detection of the disintegration of superamphiphile. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A cellulosic responsive "living" membrane.

PubMed

Qin, Guokui; Panilaitis, Bruce J; Kaplan, Zhongyuan Sun David L

2014-01-16

Bacterial cellulose has been demonstrated to be a remarkably versatile biomaterial and widely used in biomedical applications due to its unique physical properties. Here we reported for the first time a "living membrane" system based on recombinant Escherichia coli bacterial strains entrapped in cellulosic membranes produced by Gluconacetobacter xylinus. Biologically driven detection and identification of a range of target molecules presents unique challenges, and requires that detection methods are developed to be rapid, specific and sensitive. The compatibility of G. xylinus and recombinant E. coli strains was first investigated for co-cultivation, and the relationship between the number of entrapped E. coli and the level of inducible signal achieved was further explored by fluorescent signal observation in confocal microscopy. Finally to amplify the response to inducers for maximum fluorescent signal, a positive-feedback genetic amplifier was designed within recombinant E. coli strain entrapped in the living cellulosic membrane system, allowing for the detection mechanism to be extremely sensitive and resulting in a significant fluorescent signal from a single receptor binding event. The living membrane system proposed here will create devices of greater complexity in function for applications in biological and chemical detection. Copyright © 2013. Published by Elsevier Ltd.

Tunable lasers and their application in analytical chemistry

NASA Technical Reports Server (NTRS)

Steinfeld, J. I.

1975-01-01

The impact that laser techniques might have in chemical analysis is examined. Absorption, scattering, and heterodyne detection is considered. Particular emphasis is placed on the advantages of using frequency-tunable sources, and dye solution lasers are regarded as the outstanding example of this type of laser. Types of spectroscopy that can be carried out with lasers are discussed along with the ultimate sensitivity or minimum detectable concentration of molecules that can be achieved with each method. Analytical applications include laser microprobe analysis, remote sensing and instrumental methods such as laser-Raman spectroscopy, atomic absorption/fluorescence spectrometry, fluorescence assay techniques, optoacoustic spectroscopy, and polarization measurements. The application of lasers to spectroscopic methods of analysis would seem to be a rewarding field both for research in analytical chemistry and for investments in instrument manufacturing.

Nanostructured Surfaces and Detection Instrumentation for Photonic Crystal Enhanced Fluorescence

PubMed Central

Chaudhery, Vikram; George, Sherine; Lu, Meng; Pokhriyal, Anusha; Cunningham, Brian T.

2013-01-01

Photonic crystal (PC) surfaces have been demonstrated as a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics and life science research. PCs can be engineered to support optical resonances at specific wavelengths at which strong electromagnetic fields are utilized to enhance the intensity of surface-bound fluorophore excitation. Meanwhile, the leaky resonant modes of PCs can be used to direct emitted photons within a narrow range of angles for more efficient collection by a fluorescence detection system. The multiplicative effects of enhanced excitation combined with enhanced photon extraction combine to provide improved signal-to-noise ratios for detection of fluorescent emitters, which in turn can be used to reduce the limits of detection of low concentration analytes, such as disease biomarker proteins. Fabrication of PCs using inexpensive manufacturing methods and materials that include replica molding on plastic, nano-imprint lithography on quartz substrates result in devices that are practical for single-use disposable applications. In this review, we will describe the motivation for implementing high-sensitivity fluorescence detection in the context of molecular diagnosis and gene expression analysis though the use of PC surfaces. Recent efforts to improve the design and fabrication of PCs and their associated detection instrumentation are summarized, including the use of PCs coupled with Fabry-Perot cavities and external cavity lasers. PMID:23624689

Detecting crop population growth using chlorophyll fluorescence imaging.

PubMed

Wang, Heng; Qian, Xiangjie; Zhang, Lan; Xu, Sailong; Li, Haifeng; Xia, Xiaojian; Dai, Liankui; Xu, Liang; Yu, Jingquan; Liu, Xu

2017-12-10

For both field and greenhouse crops, it is challenging to evaluate their growth information on a large area over a long time. In this work, we developed a chlorophyll fluorescence imaging-based system for crop population growth information detection. Modular design was used to make the system provide high-intensity uniform illumination. This system can perform modulated chlorophyll fluorescence induction kinetics measurement and chlorophyll fluorescence parameter imaging over a large area of up to 45  cm×34  cm. The system can provide different lighting intensity by modulating the duty cycle of its control signal. Results of continuous monitoring of cucumbers in nitrogen deficiency show the system can reduce the judge error of crop physiological status and improve monitoring efficiency. Meanwhile, the system is promising in high throughput application scenarios.

Triplex DNA formation-mediated strand displacement reaction for highly sensitive fluorescent detection of melamine.

PubMed

Liu, Xiaojuan; Xu, Ningning; Gai, Panpan; Li, Feng

2018-08-01

Since melamine is a strong hazard to human health, the development of new methods for highly sensitive detection of melamine is highly desirable. Herein, a novel fluorescent biosensing strategy was designed for sensitive and selective melamine assay based on the recognition ability of abasic (AP) site in triplex towards melamine and signal amplification by Mg 2+ -dependent DNAzyme. In this strategy, the melamine-induced formation of triplex DNA was employed to trigger the strand displacement reaction (SDR). The SDR process converted the specific target recognition into the release and activation of Mg 2+ -dependent DNAzyme, which could catalyze the cleavage of fluorophore/quencher labeled DNA substrate (FQ), resulting in a significantly increased fluorescent signal. Under the optimal conditions, the fluorescent signal has a linear relationship with the logarithm of the melamine concentration in a wide range of 0.005-50 μM. The detection limit was estimated to be 0.9 nM (0.1ppb), which is sufficiently sensitive for practical application. Furthermore, this strategy exhibits high selectivity against other potential interfering substances, and the practical application of this strategy for milk samples reveals that the proposed strategy works well for melamine assay in real samples. Therefore, this strategy presents a new method for the sensitive melamine assay and holds great promise for sensing applications in the environment and the food safety field. Copyright © 2018 Elsevier B.V. All rights reserved.

Magnetic porous carbon nanocomposites derived from metal-organic frameworks as a sensing platform for DNA fluorescent detection.

PubMed

Tan, Hongliang; Tang, Gonge; Wang, Zhixiong; Li, Qian; Gao, Jie; Wu, Shimeng

2016-10-12

Metal-organic frameworks (MOFs) have emerged as very fascinating functional materials due to their tunable nature and diverse applications. In this work, we prepared a magnetic porous carbon (MPC) nanocomposite by employing iron-containing MOFs (MIL-88A) as precursors through a one-pot thermolysis method. It was found that the MPC can absorb selectively single-stranded DNA (ssDNA) probe to form MPC/ssDNA complex and subsequently quench the labelled fluorescent dye of the ssDNA probe, which is resulted from the synergetic effect of magnetic nanoparticles and carbon matrix. Upon the addition of complementary target DNA, however, the absorbed ssDNA probe could be released from MPC surface by forming double-stranded DNA with target DNA, and accompanied by the recovery of the fluorescence of ssDNA probe. Based on these findings, a sensing platform with low background signal for DNA fluorescent detection was developed. The proposed sensing platform exhibits high sensitivity with detection limit of 1 nM and excellent selectivity to specific target DNA, even single-base mismatched nucleotide can be distinguished. We envision that the presented study would provide a new perspective on the potential applications of MOF-derived nanocomposites in biomedical fields. Copyright © 2016 Elsevier B.V. All rights reserved.

Nitrogen doped carbon nanodots as fluorescent probes for selective detection and quantification of Ferric(III) ions

NASA Astrophysics Data System (ADS)

Chin, Suk-Fun; Tan, Shao-Chien; Pang, Suh-Cem; Ng, Sing-Muk

2017-11-01

Nitrogen (N) doped carbon dots (N-CDs) that showed blue fluorescence with quantum yield (QY) of 12.25% were synthesized by one step microwave irradiation of lysine in ortho-phosphoric acid at 1000 W for 5 min. The as-synthesized N-CDs were successfully explored as fluorescent probes for selective detection of ferric (Fe3+) ions in aqueous condition with a linear range from 0.2 to 5.0 mM and a detection limit of 0.074 mM ± 0.081 (S/N = 3). The N-CDs exhibited high selectivity towards the detection of Fe3+ ions even in the presence of interfering ions. The N-CDs also demonstrated the potential of practical application for determining of Fe3+ ions concentration in real samples with high recovery rate and low relative standard deviation error.

Fluorescence in-situ hybridization (FISH) as a tool for visualization and enumeration of Campylobacter in broiler ceca

USDA-ARS?s Scientific Manuscript database

Food-borne human pathogens are typically detected and enumerated by either cultural methods or PCR-based approaches. Fluorescence in-situ hybridization (FISH) is a standard microscopy tool for microbial ecology but has not been widely used for food safety applications despite important advantages o...

Gold-FISH: A correlative approach to microscopic imaging of single microbial cells in environmental samples

NASA Astrophysics Data System (ADS)

Schmidt, Hannes; Seki, David; Woebken, Dagmar; Eickhorst, Thilo

2017-04-01

Fluorescence in situ hybridization (FISH) is routinely used for the phylogenetic identification, detection, and quantification of single microbial cells environmental microbiology. Oligonucleotide probes that match the 16S rRNA sequence of target organisms are generally applied and the resulting signals are visualized via fluorescence microscopy. Consequently, the detection of the microbial cells of interest is limited by the resolution and the sensitivity of light microscopy where objects smaller than 0.2 µm can hardly be represented. Visualizing microbial cells at magnifications beyond light microscopy, however, can provide information on the composition and potential complexity of microbial habitats - the actual sites of nutrient cycling in soil and sediments. We present a recently developed technique that combines (1) the phylogenetic identification and detection of individual microorganisms by epifluorescence microscopy, with (2) the in situ localization of gold-labelled target cells on an ultrastructural level by SEM. Based on 16S rRNA targeted in situ hybridization combined with catalyzed reporter deposition, a streptavidin conjugate labeled with a fluorescent dye and nanogold particles is introduced into whole microbial cells. A two-step visualization process including an autometallographic enhancement of nanogold particles then allows for either fluorescence or electron microscopy, or a correlative application thereof. We will present applications of the Gold-FISH protocol to samples of marine sediments, agricultural soils, and plant roots. The detection and enumeration of bacterial cells in soil and sediment samples was comparable to CARD-FISH applications via fluorescence microscopy. Examples of microbe-surface interaction analysis will be presented on the basis of bacteria colonizing the rhizoplane of rice roots. In principle, Gold-FISH can be performed on any material to give a snapshot of microbe-surface interactions and provides a promising tool for the acquisition of correlative information on microorganisms within their respective habitats.

Fluorescence triggering: A general strategy for enumerating and phenotyping extracellular vesicles by flow cytometry.

PubMed

Arraud, Nicolas; Gounou, Céline; Turpin, Delphine; Brisson, Alain R

2016-02-01

Plasma contains cell-derived extracellular vesicles (EVs) which participate in various physiopathological processes and have potential biomedical applications. Despite intense research activity, knowledge on EVs is limited mainly due to the difficulty of isolating and characterizing sub-micrometer particles like EVs. We have recently reported that a simple flow cytometry (FCM) approach based on triggering the detection on a fluorescence signal enabled the detection of 50× more Annexin-A5 binding EVs (Anx5+ EVs) in plasma than the conventional FCM approach based on light scattering triggering. Here, we present the application of the fluorescence triggering approach to the enumeration and phenotyping of EVs from platelet free plasma (PFP), focusing on CD41+ and CD235a+ EVs, as well as their sub-populations which bind or do not bind Anx5. Higher EV concentrations were detected by fluorescence triggering as compared to light scattering triggering, namely 40× for Anx5+ EVs, 75× for CD41+ EVs, and 15× for CD235a+ EVs. We found that about 30% of Anx5+ EVs were of platelet origin while only 3% of them were of erythrocyte origin. In addition, a majority of EVs from platelet and erythrocyte origin do not expose PS, in contrast to the classical theory of EV formation. Furthermore, the same PFP samples were analyzed fresh and after freeze-thawing, showing that freeze-thawing processes induce an increase, of about 35%, in the amount of Anx5+ EVs, while the other EV phenotypes remain unchanged. The method of EV detection and phenotyping by fluorescence triggering is simple, sensitive and reliable. We foresee that its application to EV studies will improve our understanding on the formation mechanisms and functions of EVs in health and disease and help the development of EV-based biomarkers. © 2015 International Society for Advancement of Cytometry.

A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

NASA Astrophysics Data System (ADS)

Dai, Yanpeng; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xu, Kuoxi; Pang, Xiaobin

2017-08-01

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2 + ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2 + ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu2 + to probe QP was found to be 2.12 × 104 M- 1. Further, the Cu2 + ensemble of probe QP was found to respond H2PO4- and HPO42 - among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2 + cation and H2PO4- and HPO42 - anions in living cells.

A quinoline-based Cu2+ ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells.

PubMed

Dai, Yanpeng; Wang, Peng; Fu, Jiaxin; Yao, Kun; Xu, Kuoxi; Pang, Xiaobin

2017-08-05

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu 2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu 2+ ion was determined to be 1:1 through fluorescence titration, Job's plot and ESI-MS. The binding constant (K) of Cu 2+ to probe QP was found to be 2.12×10 4 M -1 . Further, the Cu 2+ ensemble of probe QP was found to respond H 2 PO 4 - and HPO 4 2- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu 2+ cation and H 2 PO 4 - and HPO 4 2- anions in living cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Paper-polymer composite devices with minimal fluorescence background.

PubMed

Wang, Chang-Ming; Chen, Chong-You; Liao, Wei-Ssu

2017-04-22

Polymer film incorporated paper-based devices show advantages in simplicity and rugged backing. However, their applications are restricted by the high fluorescence background interference of conventional laminating pouches. Herein, we report a straightforward approach for minimal fluorescence background device fabrication, in which filter paper was shaped and laminated in between two biaxially oriented polypropylene (OPP) and polyvinyl butyral (PVB) composite films. This composite film provides mechanical strength for enhanced device durability, protection from environmental contamination, and prevents reagent degradation. This approach was tested by the determination of copper ions with a fluorescent probe, while the detection of glucose was used to illustrate the improved device durability. Our results show that lamination by the polymer composite lengthens device lifetime, while allowing for fluorescence detection methods combination with greatly reduced fluorescent background widely present in commercially available lamination pouches. By the combination of rapid device prototyping with low cost materials, we believe that this composite design would further expand the potential of paper-based devices. Copyright © 2017 Elsevier B.V. All rights reserved.

Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

DOE PAGES

Upadhyayula, Venkata K. K.; Ghoshroy, Soumitra; Nair, Vinod S.; ...

2008-01-01

Tmore » he possibility of using single-walled carbon nanotubes (SWCNs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. he Freundlich adsorption equilibrium constant ( k ) for S.aureus and E.coli determined from batch adsorption study was found to be 9 × 10 8 and 2 × 10 8  ml/g, respectively. he visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. he results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. his is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.« less

LABONFOIL: investigations regarding microfluidic skin patches for drug detection using flexible OLEDs

NASA Astrophysics Data System (ADS)

Scholles, M.; Kroker, L.; Vogel, U.; Krüger, J.; Walczak, R.; Ruano-Lopez, J.

2010-02-01

This contribution describes first results concerning the overall and especially optical system design of microfluidic skin patches for drug detection based on fluorescence analysis of sweat samples. This work has been carried out within the European project LABONFOIL which aims to develop low-cost lab-on-chip systems for four different applications, one of them for the detection of cocaine abuse by professional drivers. To date work has focused on the integrated design of the skin patch itself including methods for sweat collection as well as studies concerning the feasibility of OLEDs for optical excitation of the fluorescence signal.

Synthesis and characterization of bioactive conjugated near-infrared fluorescent proteinoid-poly(L-lactic acid) hollow nanoparticles for optical detection of colon cancer

PubMed Central

Kolitz-Domb, Michal; Corem-Salkmon, Enav; Grinberg, Igor; Margel, Shlomo

2014-01-01

Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with colon cancer. Near-infrared (NIR) fluorescent nanoparticles are promising candidates for use as contrast agents for tumor detection. Using NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum: lower autofluorescence of biological tissues and lower absorbance and, consequently, deeper penetration into biomatrices. The present study describes the preparation of new NIR fluorescent proteinoid-poly(L-lactic acid) (PLLA) nanoparticles. For this purpose, a P(EF-PLLA) random copolymer was prepared by thermal copolymerization of L-glutamic acid (E) with L-phenylalanine (F) and PLLA. Under suitable conditions, this proteinoid-PLLA copolymer can self-assemble to nanosized hollow particles of relatively narrow size distribution. This self-assembly process was used for encapsulation of the NIR dye indocyanine green. The encapsulation process increases significantly the photostability of the dye. These NIR fluorescent nanoparticles were found to be stable and nontoxic. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline containing 4% human serum albumin was not detected. Tumor-targeting ligands such as peanut agglutinin and anticarcinoembryonic antigen antibodies were covalently conjugated to the surface of the NIR fluorescent P(EF-PLLA) nanoparticles, thereby increasing the fluorescent signal of tumors with upregulated corresponding receptors. Specific colon tumor detection by the NIR fluorescent P(EF-PLLA) nanoparticles was demonstrated in a chicken embryo model. In future work, we plan to extend this study to a mouse model, as well as to encapsulate a cancer drug such as doxorubicin within these nanoparticles for therapeutic applications. PMID:25382975

Integrated bio-fluorescence sensor.

PubMed

Thrush, Evan; Levi, Ofer; Ha, Wonill; Wang, Ke; Smith, Stephen J; Harris, James S

2003-09-26

Due to the recent explosion in optoelectronics for telecommunication applications, novel optoelectronic sensing structures can now be realized. In this work, we explore the integration of optoelectronic components towards miniature and portable fluorescence sensors. The integration of these micro-fabricated sensors with microfluidics and capillary networks may reduce the cost and complexity of current research instruments and open up a world of new applications in portable biological analysis systems. A novel optoelectronic design that capitalizes on current vertical-cavity surface-emitting laser (VCSEL) technology is explored. Specifically, VCSELs, optical emission filters and PIN photodetectors are fabricated as part of a monolithically integrated near-infrared fluorescence detection system. High-performance lasers and photodetectors have been characterized and integrated to form a complete sensor. Experimental results show that sensor sensitivity is limited by laser background. The laser background is caused by spontaneous emission emitted from the side of the VCSEL excitation source. Laser background will limit sensitivity in most integrated sensing designs due to locating excitation sources and photodetectors in such close proximity, and methods are proposed to reduce the laser background in such designs so that practical fluorescent detection limits can be achieved.

Poly-adenine-mediated fluorescent spherical nucleic acid probes for live-cell imaging of endogenous tumor-related mRNA.

PubMed

Zhu, Dan; Zhao, Dongxia; Huang, Jiaxuan; Zhu, Yu; Chao, Jie; Su, Shao; Li, Jiang; Wang, Lihua; Shi, Jiye; Zuo, Xiaolei; Weng, Lixing; Li, Qian; Wang, Lianhui

2018-05-16

Identification of tumor-related mRNA in living cells hold great promise for early cancer diagnosis and pathological research. Herein, we present poly-adenine (polyA)-mediated fluorescent spherical nucleic acid (FSNA) probes for intracellular mRNA detection with regulable sensitivities by programmably adjusting the loading density of DNA on gold nano-interface. Gold nanoparticles (AuNPs) functionalized with polyA-tailed recognition sequences were hybridized to fluorescent "reporter" strands to fabricate fluorescence-quenched FSNA probes. While exposed to target gene, the "reporter" strands were released from FSNA through strand displacement and fluorescence was recovered. With polyA20 tail as the attaching block, the detection limit of FSNA probes was calculated to be 0.31 nM, which is ~55 fold lower than that of thiolated probes without surface density regulation. Quantitative intracellular mRNA detection and imaging could be achieved with polyA-mediated FSNA probes within 2 hours, indicating their application potential in rapid and sensitive intracellular target imaging. Copyright © 2018. Published by Elsevier Inc.

Ultra-small dye-doped silica nanoparticles via modified sol-gel technique

NASA Astrophysics Data System (ADS)

Riccò, R.; Nizzero, S.; Penna, E.; Meneghello, A.; Cretaio, E.; Enrichi, F.

2018-05-01

In modern biosensing and imaging, fluorescence-based methods constitute the most diffused approach to achieve optimal detection of analytes, both in solution and on the single-particle level. Despite the huge progresses made in recent decades in the development of plasmonic biosensors and label-free sensing techniques, fluorescent molecules remain the most commonly used contrast agents to date for commercial imaging and detection methods. However, they exhibit low stability, can be difficult to functionalise, and often result in a low signal-to-noise ratio. Thus, embedding fluorescent probes into robust and bio-compatible materials, such as silica nanoparticles, can substantially enhance the detection limit and dramatically increase the sensitivity. In this work, ultra-small fluorescent silica nanoparticles (NPs) for optical biosensing applications were doped with a fluorescent dye, using simple water-based sol-gel approaches based on the classical Stöber procedure. By systematically modulating reaction parameters, controllable size tuning of particle diameters as low as 10 nm was achieved. Particles morphology and optical response were evaluated showing a possible single-molecule behaviour, without employing microemulsion methods to achieve similar results. [Figure not available: see fulltext.

Detection of λ-cyhalothrin by a core-shell spherical SiO2-based surface thin fluorescent molecularly imprinted polymer film.

PubMed

Gao, Lin; Han, Wenjuan; Li, Xiuying; Wang, Jixiang; Yan, Yongsheng; Li, Chunxiang; Dai, Jiangdong

2015-12-01

A fluorescent core-shell molecularly imprinted polymer based on the surface of SiO2 beads was synthesized and its application in the fluorescence detection of ultra-trace λ-cyhalothrin (LC) was investigated. The shell was prepared by copolymerization of acrylamide with allyl fluorescein in the presence of LC to form recognition sites. The experimental results showed that the thin fluorescent molecularly imprinted polymer (FMIP) film exhibited better selective recognition ability than fluorescent molecularly non-imprinted polymer (FNIP). A new nonlinear relationship between quenching rate and concentration was found in this work. In addition, the nonlinear relationship allowed a lower concentration range of 0-5.0 nM to be described by the Stern-Volmer equation with a correlation coefficient of 0.9929. The experiment results revealed that the SiO2@FMIP was satisfactory as a recognition element for determination of LC in soda water samples. Therefore this study demonstrated the potential of MIP for the recognition and detection of LC in food.

Image overlay solution based on threshold detection for a compact near infrared fluorescence goggle system

NASA Astrophysics Data System (ADS)

Gao, Shengkui; Mondal, Suman B.; Zhu, Nan; Liang, RongGuang; Achilefu, Samuel; Gruev, Viktor

2015-01-01

Near infrared (NIR) fluorescence imaging has shown great potential for various clinical procedures, including intraoperative image guidance. However, existing NIR fluorescence imaging systems either have a large footprint or are handheld, which limits their usage in intraoperative applications. We present a compact NIR fluorescence imaging system (NFIS) with an image overlay solution based on threshold detection, which can be easily integrated with a goggle display system for intraoperative guidance. The proposed NFIS achieves compactness, light weight, hands-free operation, high-precision superimposition, and a real-time frame rate. In addition, the miniature and ultra-lightweight light-emitting diode tracking pod is easy to incorporate with NIR fluorescence imaging. Based on experimental evaluation, the proposed NFIS solution has a lower detection limit of 25 nM of indocyanine green at 27 fps and realizes a highly precise image overlay of NIR and visible images of mice in vivo. The overlay error is limited within a 2-mm scale at a 65-cm working distance, which is highly reliable for clinical study and surgical use.

Tracking of Mesenchymal Stem Cells with Fluorescence Endomicroscopy Imaging in Radiotherapy-Induced Lung Injury

NASA Astrophysics Data System (ADS)

Perez, Jessica R.; Ybarra, Norma; Chagnon, Frederic; Serban, Monica; Lee, Sangkyu; Seuntjens, Jan; Lesur, Olivier; El Naqa, Issam

2017-01-01

Mesenchymal stem cells (MSCs) have potential for reducing inflammation and promoting organ repair. However, limitations in available techniques to track them and assess this potential for lung repair have hindered their applicability. In this work, we proposed, implemented and evaluated the use of fluorescence endomicroscopy as a novel imaging tool to track MSCs in vivo. MSCs were fluorescently labeled and injected into a rat model of radiation-induced lung injury via endotracheal (ET) or intravascular (IV) administration. Our results show that MSCs were visible in the lungs with fluorescence endomicroscopy. Moreover, we developed an automatic cell counting algorithm to quantify the number of detected cells in each condition. We observed a significantly higher number of detected cells in ET injection compared to IV and a slight increase in the mean number of detected cells in irradiated lungs compared to control, although the latter did not reach statistical significance. Fluorescence endomicroscopy imaging is a powerful new minimally invasive and translatable tool that can be used to track and quantify MSCs in the lungs and help assess their potential in organ repair.

An instrument design for non-contact detection of biomolecules and minerals on Mars using fluorescence.

PubMed

Smith, Heather D; McKay, Christopher P; Duncan, Andrew G; Sims, Ronald C; Anderson, Anne J; Grossl, Paul R

2014-01-01

We discuss fluorescence as a method to detect polycyclic aromatic hydrocarbons and other organic molecules, as well as minerals on the surface of Mars. We present an instrument design that is adapted from the ChemCam instrument which is currently on the Mars Science Lander Rover Curiosity and thus most of the primary components are currently flight qualified for Mars surface operations, significantly reducing development costs. The major change compared to ChemCam is the frequency multipliers of the 1064 nm laser to wavelengths suitable for fluorescence excitation (266 nm, 355 nm, and 532 nm). We present fluorescence spectrum for a variety of organics and minerals relevant to the surface of Mars. Preliminary results show minerals already known on Mars, such as perchlorate, fluoresce strongest when excited by 355 nm. Also we demonstrate that polycyclic aromatic hydrocarbons, such as those present in Martian meteorites, are highly fluorescent at wavelengths in the ultraviolet (266 nm, 355 nm), but not as much in the visible (532 nm). We conclude that fluorescence can be an important method for Mars applications and standoff detection of organics and minerals. The instrument approach described in this paper builds on existing hardware and offers high scientific return for minimal cost for future missions.

An instrument design for non-contact detection of biomolecules and minerals on Mars using fluorescence

PubMed Central

2014-01-01

We discuss fluorescence as a method to detect polycyclic aromatic hydrocarbons and other organic molecules, as well as minerals on the surface of Mars. We present an instrument design that is adapted from the ChemCam instrument which is currently on the Mars Science Lander Rover Curiosity and thus most of the primary components are currently flight qualified for Mars surface operations, significantly reducing development costs. The major change compared to ChemCam is the frequency multipliers of the 1064 nm laser to wavelengths suitable for fluorescence excitation (266 nm, 355 nm, and 532 nm). We present fluorescence spectrum for a variety of organics and minerals relevant to the surface of Mars. Preliminary results show minerals already known on Mars, such as perchlorate, fluoresce strongest when excited by 355 nm. Also we demonstrate that polycyclic aromatic hydrocarbons, such as those present in Martian meteorites, are highly fluorescent at wavelengths in the ultraviolet (266 nm, 355 nm), but not as much in the visible (532 nm). We conclude that fluorescence can be an important method for Mars applications and standoff detection of organics and minerals. The instrument approach described in this paper builds on existing hardware and offers high scientific return for minimal cost for future missions. PMID:25057291

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection.

PubMed

Chen, Disheng; Lander, Gary R; Flagg, Edward B

2017-10-13

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). Resonant excitation without fluorescence detection - for example, a differential transmission measurement - can determine some properties of the emitting system, but does not allow applications or measurements based on the emitted photons. For example, the measurement of photon correlations, observation of the Mollow triplet, and realization of single photon sources all require collection of the fluorescence. Incoherent excitation with fluorescence detection - for example, above band-gap excitation - can be used to create single photon sources, but the disturbance of the environment due to the excitation reduces the indistinguishability of the photons. Single photon sources based on QDs will have to be resonantly excited to have high photon indistinguishability, and simultaneous collection of the photons will be necessary to make use of them. We demonstrate a method to resonantly excite a single QD embedded in a planar cavity by coupling the excitation beam into this cavity from the cleaved face of the sample while collecting the fluorescence along the sample's surface normal direction. By carefully matching the excitation beam to the waveguide mode of the cavity, the excitation light can couple into the cavity and interact with the QD. The scattered photons can couple to the Fabry-Perot mode of the cavity and escape in the surface normal direction. This method allows complete freedom in the detection polarization, but the excitation polarization is restricted by the propagation direction of the excitation beam. The fluorescence from the wetting layer provides a guide to align the collection path with respect to the excitation beam. The orthogonality of the excitation and detection modes enables resonant excitation of a single QD with negligible laser scattering background.

Illuminating necrosis: From mechanistic exploration to preclinical application using fluorescence molecular imaging with indocyanine green

PubMed Central

Fang, Cheng; Wang, Kun; Zeng, Chaoting; Chi, Chongwei; Shang, Wenting; Ye, Jinzuo; Mao, Yamin; Fan, Yingfang; Yang, Jian; Xiang, Nan; Zeng, Ning; Zhu, Wen; Fang, Chihua; Tian, Jie

2016-01-01

Tissue necrosis commonly accompanies the development of a wide range of serious diseases. Therefore, highly sensitive detection and precise boundary delineation of necrotic tissue via effective imaging techniques are crucial for clinical treatments; however, no imaging modalities have achieved satisfactory results to date. Although fluorescence molecular imaging (FMI) shows potential in this regard, no effective necrosis-avid fluorescent probe has been developed for clinical applications. Here, we demonstrate that indocyanine green (ICG) can achieve high avidity of necrotic tissue owing to its interaction with lipoprotein (LP) and phospholipids. The mechanism was explored at the cellular and molecular levels through a series of in vitro studies. Detection of necrotic tissue and real-time image-guided surgery were successfully achieved in different organs of different animal models with the help of FMI using in house-designed imaging devices. The results indicated that necrotic tissue with a 0.6 mm diameter could be effectively detected with precise boundary definition. We believe that the new discovery and the associated imaging techniques will improve personalized and precise surgery in the near future. PMID:26864116

The Fraunhofer line discriminator: An airborne fluorometer

NASA Technical Reports Server (NTRS)

Stoertz, G. E.

1969-01-01

An experimental Fraunhofer Line Discriminator (FLD) can differentiate and measure solar-stimulated luminescence when viewed against a background of reflected light. Key elements are two extremely sensitive photomultipliers, two glass-spaced Fabry-Perot filters having a bandwidth less than 1 A, and an analog computer. As in conventional fluorometers, concentration of a fluorescent substance is measured by comparison with standards. Quantitative use is probably accurate only at low altitudes but detection of luminescent substances should be possible from any altitude. Applications of the present FLD include remote sensing of fluorescent dyes used in studies of current dynamics. The basic technique is applicable to detection of oil spills, monitoring of pollutants, and sensing over land areas.

Fluorescence Quenching of CdSe/ZnS Quantum Dots by Using Black Hole Quencher Molecules Intermediated With Peptide for Biosensing Application.

PubMed

Pillai, Sreenadh Sasidharan; Yukawa, Hiroshi; Onoshima, Daisuke; Biju, Vasudevanpillai; Baba, Yoshinobu

2015-12-17

Quantum dots (QDs) have recently been investigated as fluorescent probes for detecting a very small number of biomolecules and live cells; however, the establishment of molecular imaging technology with on-off control of QD fluorescence remains to be established. Here we have achieved the fluorescence off state of QDs with the conjugation of black hole quencher (BHQ) molecules intermediated with peptide by using streptavidin-QDs585 and biotin-pep-BHQ-1. The fluorescence of streptavidin-QDs585 was decreased by the addition of biotin-pep-BHQ-1 in a dose-dependent manner. It has been suggested that the decrease in QDs585 fluorescence occurred through a Förster resonance energy transfer (FRET) mechanism from the analysis of fluorescence intensity and lifetime of streptavidin-QDs585 and QDs585-pep-BHQ-1. QDs585 fluorescence could be quenched by more than 60% efficiency in this system. The sequence of intermediate peptide (pep) was GPLGVRGK, which can be cleaved by matrix metalloproteinases (MMPs) produced by cancer cells. QDs585-pep-BHQ-1 is thus expected to detect the MMP production by the recovery of QDs585 fluorescence as a new bioanalytical agent for molecular imaging.

Guide to red fluorescent proteins and biosensors for flow cytometry.

PubMed

Piatkevich, Kiryl D; Verkhusha, Vladislav V

2011-01-01

Since the discovery of the first red fluorescent protein (RFP), named DsRed, 12 years ago, a wide pallet of red-shifted fluorescent proteins has been cloned and biotechnologically developed into monomeric fluorescent probes for optical microscopy. Several new types of monomeric RFPs that change the emission wavelength either with time, called fluorescent timers, or after a brief irradiation with violet light, known as photoactivatable proteins, have been also engineered. Moreover, RFPs with a large Stokes shift of fluorescence emission have been recently designed. Because of their distinctive excitation and fluorescence detection conditions developed specifically for microscopy, these fluorescent probes can be suboptimal for flow cytometry. Here, we have selected and summarized the advanced orange, red, and far-red fluorescent proteins with the properties specifically required for the flow cytometry applications. Their effective brightness was calculated for the laser sources available for the commercial flow cytometers and sorters. Compatibility of the fluorescent proteins of different colors in a multiparameter flow cytometry was determined. Novel FRET pairs, utilizing RFPs, RFP-based intracellular biosensors, and their application to a high-throughput screening, are also discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

Curcumin-cysteine and curcumin-tryptophan conjugate as fluorescence turn on sensors for picric Acid in aqueous media.

PubMed

Gogoi, Bedanta; Sen Sarma, Neelotpal

2015-06-03

Rapid detection of picric acid in real sample is of outmost importance from the perspective of health, safety, and environment. In this study, a very simple and cost-effective detection of picric acid is accomplished by developing a couple of biobased conjugates curcumin-cysteine (CC) and curcumin-tryptophan (CT), which undergo efficient fluorescence turn on toward picric acid in aqueous media. Both the probes experience about 26.5-fold fluorescence enhancements at 70 nM concentration of the analyte. Here, the fluorescence turn on process is governed by the aggregation induced emission, which is induced from the electrostatic interaction between the conjugates with picric acid. The detection limit of CC and CT are about 13.51 and 13.54 nM of picric acid, respectively. Importantly, both the probes exhibit high selectivity and low interference of other analogues toward the detection of picric acid. In addition, the probes are highly photostable, show low response time and are practically applicable for sensing picric acid in real environmental samples, which is the ultimate goal of this work.

Ionic liquid-capped graphene quantum dots as label-free fluorescent probe for direct detection of ferricyanide.

PubMed

Sun, Xue; Qian, Yuting; Jiao, Yajie; Liu, Jiyang; Xi, Fengna; Dong, Xiaoping

2017-04-01

Despite complex molecular and atomic doping, efficient post-functionalization strategies for graphene quantum dots (GQDs) are of key importance to control the physicochemical properties and broaden the practical applications. With ionic liquid as specific modification agents, herein, the preparation of ionic liquid-capped GQDs (IL-GQDs) and its application as label-free fluorescent probe for direct detection of anion were reported. Hydroxyl-functionalized GQDs that could be easily gram-scale synthesized and possessed single-crystalline were chosen as the model GQDs. Also, the most commonly used ionic liquids, water-soluble 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF 4 ) was chosen as the model IL. Under the ultrasonic treatment, BMIMBF 4 easily composited with GQDs to form IL-GQDs. The synthesized IL-GQDs were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and fluorescence (FL) spectrum. After successful combination with IL, the excitation-independent photoluminescence behavior of GQDs presented almost no change, whereas, the anion responsiveness of IL-GQDs drastically improved, which afforded the IL-GQDs a sensitive response to Fe(CN) 6 3- . Based on the strong fluorescence quench, a facile and sensitive detection of Fe(CN) 6 3- was achieved. A wide linear range of 1.0×10 -7 to 2.5×10 -3 moll -1 with a low detection limit of 40 nmol l -1 was obtained. As the composition and properties of IL and GQDs could be easily tuned by varying the structure, ionic liquids-capped GQDs might present promising potential for their applications in sensing and catalysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of fluorescence resonance energy transfer in protein studies

PubMed Central

Ma, Linlin; Yang, Fan; Zheng, Jie

2014-01-01

Since the physical process of fluorescence resonance energy transfer (FRET) was elucidated more than six decades ago, this peculiar fluorescence phenomenon has turned into a powerful tool for biomedical research due to its compatibility in scale with biological molecules as well as rapid developments in novel fluorophores and optical detection techniques. A wide variety of FRET approaches have been devised, each with its own advantages and drawbacks. Especially in the last decade or so, we are witnessing a flourish of FRET applications in biological investigations, many of which exemplify clever experimental design and rigorous analysis. Here we review the current stage of FRET methods development with the main focus on its applications in protein studies in biological systems, by summarizing the basic components of FRET techniques, most established quantification methods, as well as potential pitfalls, illustrated by example applications. PMID:25368432

Fluorometric "Switch-on" Detection of Heparin Based on a System Composed of Rhodamine-labeled Chitosan Oligosaccharide Lactate, and Graphene Oxide.

PubMed

Yun, Kyusik; Zhong, Linlin

2018-05-16

A novel fluorescence "Switch on" for the detection of heparin based on the RhB-COL/GO system was achieved. A strong fluorescence dye, Rhodamine B, was modified by chitosan oligosaccharide lactate (COL), which plays a major role in the formation of a positively charged RhB-COL complex. RhB-COL was soluble and stable in solution, which was characterized by using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. GO sheets quenched the fluorescence intensity of RhB-COL due to electron transfer from RhB to the GO surface. The decrease in fluorescence intensity of RhB-COL with increasing GO concentration was recorded using a Cary Eclipse fluorescence spectrophotometer. On the other hand, the addition of heparin replaced GO to bind with the RhB-COL surface via an electrostatic and noncovalent bond due to the abundant negative charge, which resulted in recovery of the fluorescence intensity. This RhB-COL/GO system possessed high selectivity and good sensitivity for the detection of heparin compared to other biomolecules, such as glycine, D-glucose, hyaluronic acid, L-glutamic acid, and ascorbic acid. The linear response toward heparin was measured over the range, 0-1.8 U·mL-1, with a low detection limit of 0.04 U·mL-1. The satisfactory sensing performance of RhB-COL/GO for heparin supports new "switch-on" sensor applications in heparin-related biomedical detection. © 2018 IOP Publishing Ltd.

Fluorometric ‘switch-on’ detection of heparin based on a system composed of rhodamine-labeled chitosan oligosaccharide lactate, and graphene oxide

NASA Astrophysics Data System (ADS)

Zhong, Linlin; Yun, Kyusik

2018-07-01

A novel fluorescence ‘Switch on’ for the detection of heparin based on the RhB-COL/GO system was achieved. A strong fluorescence dye, Rhodamine B, was modified by chitosan oligosaccharide lactate (COL), which plays a major role in the formation of a positively charged RhB-COL complex. RhB-COL was soluble and stable in solution, which was characterized by using Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy. GO sheets quenched the fluorescence intensity of RhB-COL due to electron transfer from RhB to the GO surface. The decrease in fluorescence intensity of RhB-COL with increasing GO concentration was recorded using a Cary Eclipse fluorescence spectrophotometer. On the other hand, the addition of heparin replaced GO to bind with the RhB-COL surface via an electrostatic and noncovalent bond due to the abundant negative charge, which resulted in recovery of the fluorescence intensity. This RhB-COL/GO system possessed high selectivity and good sensitivity for the detection of heparin compared to other biomolecules, such as glycine, D-glucose, hyaluronic acid, L-glutamic acid, and ascorbic acid. The linear response toward heparin was measured over the range, 0–1.8 U · ml‑1, with a low detection limit of 0.04 U · ml‑1. The satisfactory sensing performance of RhB-COL/GO for heparin supports new ‘switch-on’ sensor applications in heparin-related biomedical detection.

Multiplexed detection of tumor markers with multicolor quantum dots based on fluorescence polarization immunoassay.

PubMed

Tian, Jianniao; Zhou, Liujin; Zhao, Yanchun; Wang, Yuan; Peng, Yan; Zhao, Shulin

2012-04-15

A multicolor quantum dot (QD)-based nanosensor for multiplex detection of two tumor markers in a homogeneous format based on fluorescence polarization immunoassay was proposed. QDs520 and QDs620 were labeled alpha-fetoprotein(α-AFP) and carcinoembryonic antigen (CEA), respectively. After separated and purified by ultrafiltration, they were used in fluorescence polarization immunoassay for the simultaneous detection of human serum alpha-fetoprotein and carcinoembryonic antigen. Under the optimal conditions, the multi-analyte immunosensor had a wide linear range (from 0.5 ng mL(-1) to 500 ng mL(-1)) for both two tumor markers and good correlation (0.996 for α-AFP and 0.993 for CEA). The detection limits (LOD) were 0.36 ng mL(-1) for CEA and 0.28 ng mL(-1) for α-AFP (S/N=3). The carcinoembryonic antigen and fetoprotein in clinical serum samples were simultaneously detected. The results from 28 serum samples had a good agreement with enzyme-linked immunosorbent assay (ELISA). The relative standard deviation and the recovery suggested that the precision and the accuracy of this analytical method were satisfactory. This strategy with high sensitivity, good specificity, easy procedures and short analysis time shows great promise for clinical diagnoses and basic discovery. The application of QDs with longer fluorescence lifetime and small fluorescence polarization can be used for the determination of high molecular-weight substances which cannot be analyzed using dye fluorescence polarization immunoassay. Copyright © 2012 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stavis, Samuel M; Edel, Joshua B; Samiee, Kevan T

A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidicmore » channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.« less

Challenges and Opportunities for Small-Molecule Fluorescent Probes in Redox Biology Applications.

PubMed

Jiang, Xiqian; Wang, Lingfei; Carroll, Shaina L; Chen, Jianwei; Wang, Meng C; Wang, Jin

2018-02-16

The concentrations of reactive oxygen/nitrogen species (ROS/RNS) are critical to various biochemical processes. Small-molecule fluorescent probes have been widely used to detect and/or quantify ROS/RNS in many redox biology studies and serve as an important complementary to protein-based sensors with unique applications. Recent Advances: New sensing reactions have emerged in probe development, allowing more selective and quantitative detection of ROS/RNS, especially in live cells. Improvements have been made in sensing reactions, fluorophores, and bioavailability of probe molecules. In this review, we will not only summarize redox-related small-molecule fluorescent probes but also lay out the challenges of designing probes to help redox biologists independently evaluate the quality of reported small-molecule fluorescent probes, especially in the chemistry literature. We specifically highlight the advantages of reversibility in sensing reactions and its applications in ratiometric probe design for quantitative measurements in living cells. In addition, we compare the advantages and disadvantages of small-molecule probes and protein-based probes. The low physiological relevant concentrations of most ROS/RNS call for new sensing reactions with better selectivity, kinetics, and reversibility; fluorophores with high quantum yield, wide wavelength coverage, and Stokes shifts; and structural design with good aqueous solubility, membrane permeability, low protein interference, and organelle specificity. Antioxid. Redox Signal. 00, 000-000.

Rapid and sensitive detection of ketamine in blood using novel fluorescence genosensor.

PubMed

Ding, Yanjun; Li, Xingmei; Guo, Yadong; Yan, Jie; Ling, Jiang; Li, Weichen; Lan, Lingmei; Chang, Yunfeng; Cai, Jifeng; Zha, Lagabaiyla

2017-12-01

In recent years, drug abuse has been considered as a most challenging social problem that aroused public attention. Ketamine has increased in unregulated use as a 'recreational drug' in teenagers. However, there is no suitable and maneuverable detection method for ketamine in situ at the moment. Fluorescence sensor technique, with predominant recognition and simple operation, is a good potential application in drug detection. Here, we first reported a highly sensitive and selective fluorescence genosensor for rapid detection of ketamine based on DNA-templated silver nanoclusters (DNA-AgNCs) probes, in which the DNA sequence could specially recognize ketamine with high affinity. Parameters affecting detection efficiency were investigated and optimized. Under optimum conditions, the as-prepared genosensor can allow for the determination of ketamine in the concentration range of 0.0001-20 μg/mL with two linear equations: one is y = 2.84x-7.139 (R 2 = 0.987) for 0.0001-0.1 μg/mL, and the other is y = 1.87x-0.091 (R 2 = 0.962) for 0.1-20 μg/mL, and the estimated detection limit of ketamine is 0.06 ng/mL. Moreover, the feasibility of this proposed method was also demonstrated by analyzing forensic blood samples. Compared with official gas chromatography/mass spectrometry (GC/MS), this fluorescence genosensor is simple, rapid, and accurate for quantitative determination of ketamine in blood for pharmaceutical and forensic analysis. Overall, it is the first report on a fluorescence genosensor for detecting ketamine directly in blood. This research may provide a new insight for the analyst to band fluorescence genosensor technology together with drug monitoring in the battle against drug abuse and forensic examination. Graphical abstract High selectively detection of ketamine using a novel fluorescence genosensor based on DNA-AgNCs probe.

Fluorescence-based methods for the detection of pressure-induced spore germination and inactivation

NASA Astrophysics Data System (ADS)

Baier, Daniel; Reineke, Kai; Doehner, Isabel; Mathys, Alexander; Knorr, Dietrich

2011-03-01

The application of high pressure (HP) provides an opportunity for the non-thermal preservation of high-quality foods, whereas highly resistant bacterial endospores play an important role. It is known that the germination of spores can be initiated by the application of HP. Moreover, the resistance properties of spores are highly dependent on their physiological states, which are passed through during the germination. To distinguish between different physiological states and to detect the amount of germinated spores after HP treatments, two fluorescence-based methods were applied. A flow cytometric method using a double staining with SYTO 16 as an indicator for germination and propidium iodide as an indicator for membrane damage was used to detect different physiological states of the spores. During the first step of germination, the spore-specific dipicolinic acid (DPA) is released [P. Setlow, Spore germination, Curr. Opin. Microbiol. 6 (2003), pp. 550-556]. DPA reacts with added terbium to form a distinctive fluorescent complex. After measuring the fluorescence intensity at 270 nm excitation wavelength in a fluorescence spectrophotometer, the amount of germinated spores can be determined. Spores of Bacillus subtilis were treated at pressures from 150 to 600 MPa and temperatures from 37 °C to 60 °C in 0.05 M ACES buffer solution (pH 7) for dwell times of up to 2 h. During the HP treatments, inactivation up to 2log 10 cycles and thermal sensitive populations up to 4log 10 cycles could be detected by plate counts. With an increasing number of thermal sensitive spores, an increased proportion of spores in germinated states was detected by flow cytometry. Also the released amount of DPA increased during the dwell times. Moreover, a clear pressure-temperature-time-dependency was shown by screening different conditions. The fluorescence-based measurement of the released DPA can provide the opportunity of an online monitoring of the germination of spores under HP inside the HP vessel. Implementation can be done using diamond anvil cells, units with inspection glasses or by inserting an optical fiber into the HP vessel. The analytical methods used can help to understand the complex mechanism of germination and inactivation of bacterial spores. Due to its universal, process-independent character, the application of these methods is feasible for established and emerging technologies.

Improved localization of cellular membrane receptors using combined fluorescence microscopy and simultaneous topography and recognition imaging

NASA Astrophysics Data System (ADS)

Duman, M.; Pfleger, M.; Zhu, R.; Rankl, C.; Chtcheglova, L. A.; Neundlinger, I.; Bozna, B. L.; Mayer, B.; Salio, M.; Shepherd, D.; Polzella, P.; Moertelmaier, M.; Kada, G.; Ebner, A.; Dieudonne, M.; Schütz, G. J.; Cerundolo, V.; Kienberger, F.; Hinterdorfer, P.

2010-03-01

The combination of fluorescence microscopy and atomic force microscopy has a great potential in single-molecule-detection applications, overcoming many of the limitations coming from each individual technique. Here we present a new platform of combined fluorescence and simultaneous topography and recognition imaging (TREC) for improved localization of cellular receptors. Green fluorescent protein (GFP) labeled human sodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cells and endothelial cells (MyEnd) from mouse myocardium stained with phalloidin-rhodamine were used as cell systems to study AFM topography and fluorescence microscopy on the same surface area. Topographical AFM images revealed membrane features such as lamellipodia, cytoskeleton fibers, F-actin filaments and small globular structures with heights ranging from 20 to 30 nm. Combined fluorescence and TREC imaging was applied to detect density, distribution and localization of YFP-labeled CD1d molecules on α-galactosylceramide (αGalCer)-loaded THP1 cells. While the expression level, distribution and localization of CD1d molecules on THP1 cells were detected with fluorescence microscopy, the nanoscale distribution of binding sites was investigated with molecular recognition imaging by using a chemically modified AFM tip. Using TREC on the inverted light microscope, the recognition sites of cell receptors were detected in recognition images with domain sizes ranging from ~ 25 to ~ 160 nm, with the smaller domains corresponding to a single CD1d molecule.

Enhanced speed in fluorescence imaging using beat frequency multiplexing

NASA Astrophysics Data System (ADS)

Mikami, Hideharu; Kobayashi, Hirofumi; Wang, Yisen; Hamad, Syed; Ozeki, Yasuyuki; Goda, Keisuke

2016-03-01

Fluorescence imaging using radiofrequency-tagged emission (FIRE) is an emerging technique that enables higher imaging speed (namely, temporal resolution) in fluorescence microscopy compared to conventional fluorescence imaging techniques such as confocal microscopy and wide-field microscopy. It works based on the principle that it uses multiple intensity-modulated fields in an interferometric setup as excitation fields and applies frequency-division multiplexing to fluorescence signals. Unfortunately, despite its high potential, FIRE has limited imaging speed due to two practical limitations: signal bandwidth and signal detection efficiency. The signal bandwidth is limited by that of an acousto-optic deflector (AOD) employed in the setup, which is typically 100-200 MHz for the spectral range of fluorescence excitation (400-600 nm). The signal detection efficiency is limited by poor spatial mode-matching between two interfering fields to produce a modulated excitation field. Here we present a method to overcome these limitations and thus to achieve higher imaging speed than the prior version of FIRE. Our method achieves an increase in signal bandwidth by a factor of two and nearly optimal mode matching, which enables the imaging speed limited by the lifetime of the target fluorophore rather than the imaging system itself. The higher bandwidth and better signal detection efficiency work synergistically because higher bandwidth requires higher signal levels to avoid the contribution of shot noise and amplifier noise to the fluorescence signal. Due to its unprecedentedly high-speed performance, our method has a wide variety of applications in cancer detection, drug discovery, and regenerative medicine.

Improved localization of cellular membrane receptors using combined fluorescence microscopy and simultaneous topography and recognition imaging.

PubMed

Duman, M; Pfleger, M; Zhu, R; Rankl, C; Chtcheglova, L A; Neundlinger, I; Bozna, B L; Mayer, B; Salio, M; Shepherd, D; Polzella, P; Moertelmaier, M; Kada, G; Ebner, A; Dieudonne, M; Schütz, G J; Cerundolo, V; Kienberger, F; Hinterdorfer, P

2010-03-19

The combination of fluorescence microscopy and atomic force microscopy has a great potential in single-molecule-detection applications, overcoming many of the limitations coming from each individual technique. Here we present a new platform of combined fluorescence and simultaneous topography and recognition imaging (TREC) for improved localization of cellular receptors. Green fluorescent protein (GFP) labeled human sodium-glucose cotransporter (hSGLT1) expressed Chinese Hamster Ovary (CHO) cells and endothelial cells (MyEnd) from mouse myocardium stained with phalloidin-rhodamine were used as cell systems to study AFM topography and fluorescence microscopy on the same surface area. Topographical AFM images revealed membrane features such as lamellipodia, cytoskeleton fibers, F-actin filaments and small globular structures with heights ranging from 20 to 30 nm. Combined fluorescence and TREC imaging was applied to detect density, distribution and localization of YFP-labeled CD1d molecules on alpha-galactosylceramide (alphaGalCer)-loaded THP1 cells. While the expression level, distribution and localization of CD1d molecules on THP1 cells were detected with fluorescence microscopy, the nanoscale distribution of binding sites was investigated with molecular recognition imaging by using a chemically modified AFM tip. Using TREC on the inverted light microscope, the recognition sites of cell receptors were detected in recognition images with domain sizes ranging from approximately 25 to approximately 160 nm, with the smaller domains corresponding to a single CD1d molecule.

Nanozyme-based bio-barcode assay for high sensitive and logic-controlled specific detection of multiple DNAs.

PubMed

Lin, Xiaodong; Liu, Yaqing; Tao, Zhanhui; Gao, Jinting; Deng, Jiankang; Yin, Jinjin; Wang, Shuo

2017-08-15

Since HCV and HIV share a common transmission path, high sensitive detection of HIV and HCV gene is of significant importance to improve diagnosis accuracy and cure rate at early stage for HIV virus-infected patients. In our investigation, a novel nanozyme-based bio-barcode fluorescence amplified assay is successfully developed for simultaneous detection of HIV and HCV DNAs with excellent sensitivity in an enzyme-free and label-free condition. Here, bimetallic nanoparticles, PtAu NPs , present outstanding peroxidase-like activity and act as barcode to catalyze oxidation of nonfluorescent substrate of amplex red (AR) into fluorescent resorufin generating stable and sensitive "Turn On" fluorescent output signal, which is for the first time to be integrated with bio-barcode strategy for fluorescence detection DNA. Furthermore, the provided strategy presents excellent specificity and can distinguish single-base mismatched mutant from target DNA. What interesting is that cascaded INHIBIT-OR logic gate is integrated with biosensors for the first time to distinguish individual target DNA from each other under logic function control, which presents great application in development of rapid and intelligent detection. Copyright © 2017. Published by Elsevier B.V.

Fluorescence detection of glutathione and oxidized glutathione in blood with a NIR-excitable cyanine probe

NASA Astrophysics Data System (ADS)

Liu, Chang-hui; Qi, Feng-pei; Wen, Fu-bin; Long, Li-ping; Liu, Ai-juan; Yang, Rong-hua

2018-04-01

Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids, and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase and the reducing agent nicotinamideadenine dinucleotide phosphate, without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems.

A novel fluorimetric sensing platform for highly sensitive detection of organophosphorus pesticides by using egg white-encapsulated gold nanoclusters.

PubMed

Yan, Xu; Li, Hongxia; Hu, Tianyu; Su, Xingguang

2017-05-15

Assays for organophosphorus pesticides (OPs) with high sensitivity as well as on-site screening have been urgently required to protect ecosystem and prevent disease. Herein, a novel fluorimetric sensing platform was constructed for quantitative detection of OPs via tyrosinase (TYR) enzyme-controlled quenching of gold nanoclusters (AuNCs). One-step green synthetic approach was developed for the synthesis of AuNCs by using chicken egg white (CEW) as template and stabilizer. Initially, TYR can catalyze the oxidation of dopamine to dopaminechrome, which can efficiently quench the fluorescence intensity of AuNCs at 630nm based on dynamic quenching process. However, with the presence of OPs, the activity of TYR was inhibited, resulting in the fluorescence recovery of AuNCs. This proposed fluorescence platform was demonstrated to enable rapid detection for OPs (paraoxon as model) and to provide excellent sensitivity with a detection limit of 0.1ngmL -1 . Significantly, the fluorescence probe was used to prepare paper-based test strips for visual detection of OPs, which validated the excellent potential for real-time and on-site application. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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.

A miniature and field-applicable multipumping flow analyzer for ammonium monitoring in seawater with fluorescence detection.

PubMed

Horstkotte, Burkhard; Duarte, Carlos M; Cerdà, Víctor

2011-07-15

In this article, a simple, economic, and miniature flow analyzer for ammonium in seawater based on the solenoid micropumps is presented. A single reagent of sodium tetraborate, ortho-phthaldialdehyde (OPA), and sodium sulfite was used and optimized applying the modified SIMPLEX method. A special-made detection cell for fluorescence detection of the reaction product isoindol-1-sulfonat was made and combined with a commercial photomultiplier tube, a long-pass optical filter, and an UV-LED as excitation light source. A LOD down to 13 nmol/L was achieved. The fabrication and application of a miniature reaction coil heating device for reaction rate enhancement is further described. The system featured an injection frequency of 32 h(-1) at average standard deviation of 3%. Copyright © 2011 Elsevier B.V. All rights reserved.

Rapid, sensitive, and selective fluorescent DNA detection using iron-based metal-organic framework nanorods: Synergies of the metal center and organic linker.

PubMed

Tian, Jingqi; Liu, Qian; Shi, Jinle; Hu, Jianming; Asiri, Abdullah M; Sun, Xuping; He, Yuquan

2015-09-15

Considerable recent attention has been paid to homogeneous fluorescent DNA detection with the use of nanostructures as a universal "quencher", but it still remains a great challenge to develop such nanosensor with the benefits of low cost, high speed, sensitivity, and selectivity. In this work, we report the use of iron-based metal-organic framework nanorods as a high-efficient sensing platform for fluorescent DNA detection. It only takes about 4 min to complete the whole "mix-and-detect" process with a low detection limit of 10 pM and a strong discrimination of single point mutation. Control experiments reveal the remarkable sensing behavior is a consequence of the synergies of the metal center and organic linker. This work elucidates how composition control of nanostructures can significantly impact their sensing properties, enabling new opportunities for the rational design of functional materials for analytical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Selective counting and sizing of single virus particles using fluorescent aptamer-based nanoparticle tracking analysis.

PubMed

Szakács, Zoltán; Mészáros, Tamás; de Jonge, Marien I; Gyurcsányi, Róbert E

2018-05-30

Detection and counting of single virus particles in liquid samples are largely limited to narrow size distribution of viruses and purified formulations. To address these limitations, here we propose a calibration-free method that enables concurrently the selective recognition, counting and sizing of virus particles as demonstrated through the detection of human respiratory syncytial virus (RSV), an enveloped virus with a broad size distribution, in throat swab samples. RSV viruses were selectively labeled through their attachment glycoproteins (G) with fluorescent aptamers, which further enabled their identification, sizing and counting at the single particle level by fluorescent nanoparticle tracking analysis. The proposed approach seems to be generally applicable to virus detection and quantification. Moreover, it could be successfully applied to detect single RSV particles in swab samples of diagnostic relevance. Since the selective recognition is associated with the sizing of each detected particle, this method enables to discriminate viral elements linked to the virus as well as various virus forms and associations.

An excited state intramolecular proton transfer dye based fluorescence turn-on probe for fast detection of thiols and its applications in bioimaging

NASA Astrophysics Data System (ADS)

Zhao, Yun; Xue, Yuanyuan; Li, Haoyang; Zhu, Ruitao; Ren, Yuehong; Shi, Qinghua; Wang, Song; Guo, Wei

2017-03-01

In this study, a new fluorescent probe 2-(2‧-hydroxy-5‧-N-maleimide phenyl)-benzothiazole (probe 1), was designed and synthesized by linking the excited state intramolecular proton transfer (ESIPT) fluorophore to the maleimide group for selective detection of thiols in aqueous solution. The fluorescence of probe 1 is strongly quenched by maleimide group through the photo-induced electron transfer (PET) mechanism, but after reaction with thiol, the fluorescence of ESIPT fluorophore is restored, affording a large Stokes shifts. Upon addition of cysteine (Cys), probe 1 exhibited a fast response time (complete within 30 s) and a high signal-to-noise ratio (up to 23-fold). It showed a high selectivity and excellent sensitivity to thiols over other relevant biological species, with a detection limit of 3.78 × 10- 8 M (S/N = 3). Moreover, the probe was successfully applied to the imaging of thiols in living cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trainham, Clifford P.; O'Neill, Mary D.; McKenna, Ian J.

The rate equations found in frequency domain fluorescence spectroscopy are the same as those found in electronics under analog filter theory. Laplace transform methods are a natural way to solve the equations, and the methods can provide solutions for arbitrary excitation functions. The fluorescence terms can be modeled as circuit components and cascaded with drive and detection electronics to produce a global transfer function. Electronics design tools such as Spicea can be used to model fluorescence problems. In applications, such as remote sensing, where detection electronics are operated at high gain and limited bandwidth, a global modeling of the entiremore » system is important, since the filter terms of the drive and detection electronics affect the measured response of the fluorescence signals. Furthermore, the techniques described here can be used to separate signals from fast and slow fluorophores emitting into the same spectral band, and data collection can be greatly accelerated by means of a frequency comb driver waveform and appropriate signal processing of the response.« less

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

PubMed

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.

Laser-excited fluorescence of rare earth elements in fluorite: Initial observations with a laser Raman microprobe

USGS Publications Warehouse

Burruss, R.C.; Ging, T.G.; Eppinger, R.G.; Samson, a.M.

1992-01-01

Fluorescence emission spectra of three samples of fluorite containing 226-867 ppm total rare earth elements (REE) were excited by visible and ultraviolet wavelength lines of an argon ion laser and recorded with a Raman microprobe spectrometer system. Narrow emission lines ( 0.9 for Eu2+ and 0.99 for Er3+. Detection limits for three micrometer spots are about 0.01 ppm Eu2+ and 0.07 ppm Er3+. These limits are less than chondrite abundance for Eu and Er, demonstrating the potential microprobe analytical applications of laser-excited fluorescence of REE in fluorite. However, application of this technique to common rock-forming minerals may be hampered by competition between fluorescence emission and radiationless energy transfer processes involving lattice phonons. ?? 1992.

"Turn-on" fluorescence detection of lead ions based on accelerated leaching of gold nanoparticles on the surface of graphene.

PubMed

Fu, Xiuli; Lou, Tingting; Chen, Zhaopeng; Lin, Meng; Feng, Weiwei; Chen, Lingxin

2012-02-01

A novel platform for effective "turn-on" fluorescence sensing of lead ions (Pb(2+)) in aqueous solution was developed based on gold nanoparticle (AuNP)-functionalized graphene. The AuNP-functionalized graphene exhibited minimal background fluorescence because of the extraordinarily high quenching ability of AuNPs. Interestingly, the AuNP-functionalized graphene underwent fluorescence restoration as well as significant enhancement upon adding Pb(2+), which was attributed to the fact that Pb(2+) could accelerate the leaching rate of the AuNPs on graphene surfaces in the presence of both thiosulfate (S(2)O(3)(2-)) and 2-mercaptoethanol (2-ME). Consequently, this could be utilized as the basis for selective detection of Pb(2+). With the optimum conditions chosen, the relative fluorescence intensity showed good linearity versus logarithm concentration of Pb(2+) in the range of 50-1000 nM (R = 0.9982), and a detection limit of 10 nM. High selectivity over common coexistent metal ions was also demonstrated. The practical application had been carried out for determination of Pb(2+) in tap water and mineral water samples. The Pb(2+)-specific "turn-on" fluorescence sensor, based on Pb(2+) accelerated leaching of AuNPs on the surface of graphene, provided new opportunities for highly sensitive and selective Pb(2+) detection in aqueous media.

A highly sensitive protocol for microscopy of alkyne lipids and fluorescently tagged or immunostained proteins.

PubMed

Gaebler, Anne; Penno, Anke; Kuerschner, Lars; Thiele, Christoph

2016-10-01

The demand to study the cellular localization of specific lipids has led to recent advances in lipid probes and microscopy. Alkyne lipids bear a small, noninterfering tag and can be detected upon click reaction with an azide-coupled reporter. Fluorescent alkyne lipid imaging crucially depends on appropriate azide reporters and labeling protocols that allow for an efficient click reaction and therefore a sensitive detection. We synthesized several azide reporters with different spacer components and tested their suitability for alkyne lipid imaging in fixed cells. The implementation of a copper-chelating picolyl moiety into fluorescent or biotin-based azide reagents strongly increased the sensitivity of the imaging routine. We demonstrate the applicability and evaluate the performance of this approach using different lipid classes and experimental setups. As azide picolyl reporters allow for reduced copper catalyst concentrations, they also enable coimaging of alkyne lipids with multiple fluorescent proteins including enhanced green fluorescent protein. Alternatively, and as we also show, microscopy of alkyne lipids can be combined with protein detection by immunocytochemistry. In summary, we present a robust, sensitive, and highly versatile protocol for the labeling of alkyne lipids with azide-coupled reporters for fluorescence microscopy that can be combined with different protein detection and imaging techniques. Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.

Method for detecting point mutations in DNA utilizing fluorescence energy transfer

DOEpatents

Parkhurst, Lawrence J.; Parkhurst, Kay M.; Middendorf, Lyle

2001-01-01

A method for detecting point mutations in DNA using a fluorescently labeled oligomeric probe and Forster resonance energy transfer (FRET) is disclosed. The selected probe is initially labeled at each end with a fluorescence dye, which act together as a donor/acceptor pair for FRET. The fluorescence emission from the dyes changes dramatically from the duplex stage, wherein the probe is hybridized to the complementary strand of DNA, to the single strand stage, when the probe is melted to become detached from the DNA. The change in fluorescence is caused by the dyes coming into closer proximity after melting occurs and the probe becomes detached from the DNA strand. The change in fluorescence emission as a function of temperature is used to calculate the melting temperature of the complex or T.sub.m. In the case where there is a base mismatch between the probe and the DNA strand, indicating a point mutation, the T.sub.m has been found to be significantly lower than the T.sub.m for a perfectly match probelstand duplex. The present invention allows for the detection of the existence and magnitude of T.sub.m, which allows for the quick and accurate detection of a point mutation in the DNA strand and, in some applications, the determination of the approximate location of the mutation within the sequence.

Rainbow Vectors for Broad-Range Bacterial Fluorescence Labeling.

PubMed

Barbier, Mariette; Damron, F Heath

2016-01-01

Since their discovery, fluorescent proteins have been widely used to study protein function, localization or interaction, promoter activity and regulation, drug discovery or for non-invasive imaging. They have been extensively modified to improve brightness, stability, and oligomerization state. However, only a few studies have focused on understanding the dynamics of fluorescent proteins expression in bacteria. In this work, we developed a set plasmids encoding 12 fluorescent proteins for bacterial labeling to facilitate the study of pathogen-host interactions. These broad-spectrum plasmids can be used with a wide variety of Gram-negative microorganisms including Escherichia coli, Pseudomonas aeruginosa, Burkholderia cepacia, Bordetella bronchiseptica, Shigella flexneri or Klebsiella pneumoniae. For comparison, fluorescent protein expression and physical characteristics in Escherichia coli were analyzed using fluorescence microscopy, flow cytometry and in vivo imaging. Fluorescent proteins derived from the Aequorea Victoria family showed high photobleaching, while proteins form the Discosoma sp. and the Fungia coccina family were more photostable for microscopy applications. Only E2-Crimson, mCherry and mKeima were successfully detected for in vivo applications. Overall, E2-Crimson was the fastest maturing protein tested in E. coli with the best overall performance in the study parameters. This study provides a unified comparison and comprehensive characterization of fluorescent protein photostability, maturation and toxicity, and offers general recommendations on the optimal fluorescent proteins for in vitro and in vivo applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, H; Ding, H; Ziemer, B

Purpose: To investigate the feasibility of energy calibration and energy response characterization of a photon counting detector using x-ray fluorescence. Methods: A comprehensive Monte Carlo simulation study was done to investigate the influence of various geometric components on the x-ray fluorescence measurement. Different materials, sizes, and detection angles were simulated using Geant4 Application for Tomographic Emission (GATE) Monte Carlo package. Simulations were conducted using 100 kVp tungsten-anode spectra with 2 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The fluorescence material was placed 300 mm away from both themore » x-ray source and the detector. For angular dependence measurement, the distance was decreased to 30 mm to reduce the simulation time. Compound materials, containing silver, barium, gadolinium, hafnium, and gold in cylindrical shape, were simulated. The object size varied from 5 to 100 mm in diameter. The angular dependence of fluorescence and scatter were simulated from 20° to 170° with an incremental step of 10° to optimize the fluorescence to scatter ratio. Furthermore, the angular dependence was also experimentally measured using a spectrometer (X-123CdTe, Amptek Inc., MA) to validate the simulation results. Results: The detection angle between 120° to 160° resulted in more optimal x-ray fluorescence to scatter ratio. At a detection angle of 120°, the object size did not have a significant effect on the fluorescence to scatter ratio. The experimental results of fluorescence angular dependence are in good agreement with the simulation results. The Kα and Kβ peaks of five materials could be identified. Conclusion: The simulation results show that the x-ray fluorescence procedure has the potential to be used for detector energy calibration and detector response characteristics by using the optimal system geometry.« less

A magnetic/fluorometric bimodal sensor based on a carbon dots-MnO2 platform for glutathione detection

NASA Astrophysics Data System (ADS)

Xu, Yang; Chen, Xi; Chai, Ran; Xing, Chengfen; Li, Huanrong; Yin, Xue-Bo

2016-07-01

A novel magnetic/fluorometric bimodal sensor was built from carbon dots (CDs) and MnO2. The resulting sensor was sensitive to glutathione (GSH), leading to apparent enhancement of magnetic resonance (MR) and fluorescence signals along with visual changes. The bimodal detection strategy is based on the decomposition of the CDs-MnO2 through a redox reaction between GSH and MnO2. This process causes the transformation from non-MR-active MnO2 to MR-active Mn2+, and is accompanied by fluorescence restoration of CDs. Compared with a range of other CDs, the polyethylenimine (PEI) passivated CDs (denoted as pCDs) were suitable for detection due to their positive surface potential. Cross-validation between MR and fluorescence provided detailed information regarding the MnO2 reduction process, and revealed the three distinct stages of the redox process. Thus, the design of a CD-based sensor for the magnetic/fluorometric bimodal detection of GSH was emphasized for the first time. This platform showed a detection limit of 0.6 μM with a linear range of 1-200 μM in the fluorescence mode, while the MR mode exhibited a linear range of 5-200 μM and a GSH detection limit of 2.8 μM with a visible change being observed rapidly at 1 μM in the MR images. Furthermore, the introduction of the MR mode allowed the biothiols to be easily identified. The integration of CD fluorescence with an MR response was demonstrated to be promising for providing detailed information and discriminating power, and therefore extend the application of CDs in sensing and imaging.A novel magnetic/fluorometric bimodal sensor was built from carbon dots (CDs) and MnO2. The resulting sensor was sensitive to glutathione (GSH), leading to apparent enhancement of magnetic resonance (MR) and fluorescence signals along with visual changes. The bimodal detection strategy is based on the decomposition of the CDs-MnO2 through a redox reaction between GSH and MnO2. This process causes the transformation from non-MR-active MnO2 to MR-active Mn2+, and is accompanied by fluorescence restoration of CDs. Compared with a range of other CDs, the polyethylenimine (PEI) passivated CDs (denoted as pCDs) were suitable for detection due to their positive surface potential. Cross-validation between MR and fluorescence provided detailed information regarding the MnO2 reduction process, and revealed the three distinct stages of the redox process. Thus, the design of a CD-based sensor for the magnetic/fluorometric bimodal detection of GSH was emphasized for the first time. This platform showed a detection limit of 0.6 μM with a linear range of 1-200 μM in the fluorescence mode, while the MR mode exhibited a linear range of 5-200 μM and a GSH detection limit of 2.8 μM with a visible change being observed rapidly at 1 μM in the MR images. Furthermore, the introduction of the MR mode allowed the biothiols to be easily identified. The integration of CD fluorescence with an MR response was demonstrated to be promising for providing detailed information and discriminating power, and therefore extend the application of CDs in sensing and imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03129c

Application of Temperature-Dependent Fluorescent Dyes to the Measurement of Millimeter Wave Absorption in Water Applied to Biomedical Experiments

PubMed Central

Popenko, Oleksandr

2014-01-01

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects. PMID:25435859

Application of temperature-dependent fluorescent dyes to the measurement of millimeter wave absorption in water applied to biomedical experiments.

PubMed

Kuzkova, Nataliia; Popenko, Oleksandr; Yakunov, Andrey

2014-01-01

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application of this noncontact temperature sensing is a simple and novel method to detect temperature change in small biological objects.

Combination of Fluorescence-Guided Surgery With Photodynamic Therapy for the Treatment of Cancer

PubMed Central

He, Jun; Yang, Leping; Yi, Wenjun; Fan, Wentao; Wen, Yu; Miao, Xiongying; Xiong, Li

2017-01-01

Specific visualization of body parts is needed during surgery. Fluorescence-guided surgery (FGS) uses a fluorescence contrast agent for in vivo tumor imaging to detect and identify both malignant and normal tissues. There are several advantages and clinical benefits of FGS over other conventional medical imaging modalities, such as its safety, effectiveness, and suitability for real-time imaging in the operating room. Recent advancements in contrast agents and intraoperative fluorescence imaging devices have led to a greater potential for intraoperative fluorescence imaging in clinical applications. Photodynamic therapy (PDT) is an alternative modality to treat tumors, which uses a light-sensitive drug (photosensitizers) and special light to destroy the targeted tissues. In this review, we discuss the fluorescent contrast agents, some newly developed imaging devices, and the successful clinical application of FGS. Additionally, we present the combined strategy of FGS with PDT to further improve the therapeutic effect for patients with cancer. Taken together, this review provides a unique perspective and summarization of FGS. PMID:28849712

A novel dual-ratiometric-response fluorescent probe for SO2/ClO- detection in cells and in vivo and its application in exploring the dichotomous role of SO2 under the ClO- induced oxidative stress.

PubMed

Dou, Kun; Fu, Qiang; Chen, Guang; Yu, Fabiao; Liu, Yuxia; Cao, Ziping; Li, Guoliang; Zhao, Xianen; Xia, Lian; Chen, Lingxin; Wang, Hua; You, Jinmao

2017-07-01

Intracellular reactive sulfur species and reactive oxygen species play vital roles in immunologic mechanism. As an emerging signal transmitter, SO 2 can be generated as the anti-oxidant, while SO 2 is also a potential oxidative stress-inducer in organism. Aiming to elucidate in-depth the dichotomous role of SO 2 under oxidative stress, we designed a dual-response fluorescent probe that enabled the respective or successive detection of SO 2 and ClO - . The probe itself emits the red fluorescence (625 nm) which can largely switch to blue (410 nm) and green fluorescence (500 nm) respectively in response to SO 2 and ClO - , allowing the highly selective and accurate ratiometric quantification for both SO 2 and ClO - in cells. Moreover the ultrafast (SO 2 : <60 s; ClO - : within sec) and highly sensitive (detection limits: SO 2 : 3.5 nM; ClO - : 12.5 nM) detection were achieved. With the robust applicability, the developed probe was successfully used to quantify SO 2 and endogenous ClO - in respectively the HeLa cells and the RAW 264.7 cells, as well as to visualize the dynamic of SO 2 /ClO - in zebrafish. The fluorescent imaging studies and flow cytometry analysis confirmed the burst-and-depletion and meanwhile the oxidative-and-antioxidative effects of intracellular SO 2 under the NaClO induced oxidative stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fiber-optic multiphoton flow cytometry in whole blood and in vivo

NASA Astrophysics Data System (ADS)

Chang, Yu-Chung; Ye, Jing Yong; Thomas, Thommey P.; Cao, Zhengyi; Kotlyar, Alina; Tkaczyk, Eric R.; Baker, James R.; Norris, Theodore B.

2010-07-01

Circulating tumor cells in the bloodstream are sensitive indicators for metastasis and disease prognosis. Circulating cells have usually been monitored via extraction from blood, and more recently in vivo using free-space optics; however, long-term intravital monitoring of rare circulating cells remains a major challenge. We demonstrate the application of a two-photon-fluorescence optical fiber probe for the detection of cells in whole blood and in vivo. A double-clad fiber was used to enhance the detection sensitivity. Two-channel detection was employed to enable simultaneous measurement of multiple fluorescent markers. Because the fiber probe circumvents scattering and absorption from whole blood, the detected signal strength from fluorescent cells was found to be similar in phosphate-buffered saline (PBS) and in whole blood. The detection efficiency of cells labeled with the membrane-binding dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindoldicarbocyanine, 4-chlorobenzenesulfonate (DiD) was demonstrated to be the same in PBS and in whole blood. A high detection efficiency of green fluorescent protein (GFP)-expressing cells in whole blood was also demonstrated. To characterize in vivo detection, DiD-labeled untransfected and GFP-transfected cells were injected into live mice, and the cell circulation dynamics was monitored in real time. The detection efficiency of GFP-expressing cells in vivo was consistent with that observed ex vivo in whole blood.

Optical sensor for rapid microbial detection

NASA Astrophysics Data System (ADS)

Al-Adhami, Mustafa; Tilahun, Dagmawi; Rao, Govind; Kostov, Yordan

2016-05-01

In biotechnology, the ability to instantly detect contaminants is key to running a reliable bioprocess. Bioprocesses are prone to be contaminated by cells that are abundant in our environment; detection and quantification of these cells would aid in the preservation of the bioprocess product. This paper discusses the design and development of a portable kinetics fluorometer which acts as a single-excitation, single-emission photometer that continuously measures fluorescence intensity of an indicator dye, and plots it. Resazurin is used as an indicator dye since the viable contaminant cells reduce Resazurin toResorufin, the latter being strongly fluorescent. A photodiode detects fluorescence change by generating current proportional to the intensity of the light that reached it, and a trans-impedance differential op-amp ensures amplification of the photodiodes' signal. A microfluidic chip was designed specifically for the device. It acts as a fully enclosed cuvette, which enhances the Resazurin reduction rate. E. coli in LB media, along with Resazurin were injected into the microfluidic chip. The optical sensor detected the presence of E. coli in the media based on the fluorescence change that occurred in the indicator dye in concentrations as low as 10 CFU/ml. A method was devised to detect and determine an approximate amount of contamination with this device. This paper discusses application of this method to detect and estimate sample contamination. This device provides fast, accurate, and inexpensive means to optically detect the presence of viable cells.

Upconversion nanoparticle-based fluorescence resonance energy transfer assay for organophosphorus pesticides.

PubMed

Long, Qian; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

2015-06-15

This paper reports a novel nanosensor for organophosphorus pesticides based on the fluorescence resonance energy transfer (FRET) between NaYF4:Yb,Er upconversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs). The detection mechanism is based on the facts that AuNPs quench the fluorescence of UCNPs and organophosphorus pesticides (OPs) inhibit the activity of acetylcholinesterase (AChE) which catalyzes the hydrolysis of acetylthiocholine (ATC) into thiocholine. Under the optimized conditions, the logarithm of the pesticides concentration was proportional to the inhibition efficiency. The detection limits of parathion-methyl, monocrotophos and dimethoate reached 0.67, 23, and 67 ng/L, respectively. Meanwhile, the biosensor shows good sensitivity, stability, and could be successfully applied to detection of OPs in real food samples, suggesting the biosensor has potentially extensive application clinic diagnoses assays. Copyright © 2014 Elsevier B.V. All rights reserved.

Fluorescent probes for real-time measurement of nitric oxide in living cells.

PubMed

Li, Huili; Wan, Ajun

2015-11-07

Nitric oxide (NO) is an important signaling molecule in biology. Both NO excess and insufficiency have been implicated in numerous physiological and pathological conditions. In order to study the diverse biological roles of NO in cells and tissues, many techniques have been developed for assaying NO. Recently, new generations of fluorescent probes have become indispensible tools for the study of NO biology because of their sensitivity, selectivity, spatiotemporal resolution, and experimental feasibility. Rational application of these probes in the study requires the understanding of the molecular mechanism that the probes are involved in. In this review, we will present an arsenal of fluorescent probes used to detect NO in living cells and animal tissues. We will also discuss the molecular mechanisms, actualities and prospects of fluorescent probes in detecting NO in cell biology.

X-ray fluorescence tomographic system design and image reconstruction.

PubMed

Cong, Wenxiang; Shen, Haiou; Cao, Guohua; Liu, Hong; Wang, Ge

2013-01-01

In this paper, we presented a new design of x-ray fluorescence CT imaging system. For detecting fuorescence signals of gold nanoparticles in-vivo, multiple spectroscopic detectors are arranged and rotated orthogonal to an excited region of interest so that a localized scan can be acquired with a maximized efficiency. Excitation filtration was employed to minimize the effects of low-energy x-rays and background scattering for lowering radiation dose to the object. Numerical simulations showed that the radiation dose is less than 300 mGy/second for a complete 30 views tomographic scan; and the sensitivity of 3D fluorescence signal detection is up to 0.2% contrast concentrations of nanoparticles. The x-ray fluorescence computed tomography is an important molecular imaging tool. It can be used directly in samall animal research. It has great translational potential for future clinical applications.

A malonitrile-functionalized metal-organic framework for hydrogen sulfide detection and selective amino acid molecular recognition

NASA Astrophysics Data System (ADS)

Li, Haiwei; Feng, Xiao; Guo, Yuexin; Chen, Didi; Li, Rui; Ren, Xiaoqian; Jiang, Xin; Dong, Yuping; Wang, Bo

2014-03-01

A novel porous polymeric fluorescence probe, MN-ZIF-90, has been designed and synthesized for quantitative hydrogen sulfide (H2S) fluorescent detection and highly selective amino acid recognition. This distinct crystalline structure, derived from rational design and malonitrile functionalization, can trigger significant enhancement of its fluorescent intensity when exposed to H2S or cysteine molecules. Indeed this new metal-organic framework (MOF) structure shows high selectivity of biothiols over other amino acids and exhibits favorable stability. Moreover, in vitro viability assays on HeLa cells show low cytotoxicity of MN-ZIF-90 and its imaging contrast efficiency is further demonstrated by fluorescence microscopy studies. This facile yet powerful strategy also offers great potential of using open-framework materials (i.e. MOFs) as the novel platform for sensing and other biological applications.

Synthesis, optical properties and application of a set of novel pyrazole nopinone derivatives

NASA Astrophysics Data System (ADS)

Yang, Jinlai; Xu, Xu; Rui, Jian; Wang, Zhonglong; Zhang, Yan; Wang, Shifa; Wu, Liangru

2017-08-01

Pyrazole derivatives (4-6) were directly synthesized from β-pinene derivative nopinone, and they were characterized by Fourier transform infrared (FTIR) spectoscope, nuclear magnetic resonance (NMR), and mass spectrometry. Their optical properties were investigated by ultraviolet-visible spectroscopy and fluorescence spectroscopy. The three compounds emitted strong blue fluorescence in ethanol. Using a fluorescence quenching method, compound 4 could be used to detect the content (100.57%) of copper sulfate pentahydrate (≥ 99%) with a RSD of 1.98%, y = - 0.1127 × + 2.7148, R2 = 0.9703 (Cu2 +: 0.5-8.0 × 10- 5 mol/L), and compounds 4-6 also had utility of calculating the content of anhydrous ferric chloride at a wide range of concentration. Thus, compounds 4-6 are new functional fluorescents for detecting the content of some purchased products.

Multifunctional ferritin cage nanostructures for fluorescence and MR imaging of tumor cells.

PubMed

Li, Ke; Zhang, Zhi-Ping; Luo, Ming; Yu, Xiang; Han, Yu; Wei, Hong-Ping; Cui, Zong-Qiang; Zhang, Xian-En

2012-01-07

Bionanoparticles and nanostructures have attracted increasing interest as versatile and promising tools in many applications including biosensing and bioimaging. In this study, to image and detect tumor cells, ferritin cage-based multifunctional hybrid nanostructures were constructed that: (i) displayed both the green fluorescent protein and an Arg-Gly-Asp peptide on the exterior surface of the ferritin cages; and (ii) incorporated ferrimagnetic iron oxide nanoparticles into the ferritin interior cavity. The overall architecture of ferritin cages did not change after being integrated with fusion proteins and ferrimagnetic iron oxide nanoparticles. These multifunctional nanostructures were successfully used as a fluorescent imaging probe and an MRI contrast agent for specifically probing and imaging α(v)β(3) integrin upregulated tumor cells. The work provides a promising strategy for tumor cell detection by simultaneous fluorescence and MR imaging.

Optical switch probes and optical lock-in detection (OLID) imaging microscopy: high-contrast fluorescence imaging within living systems.

PubMed

Yan, Yuling; Marriott, M Emma; Petchprayoon, Chutima; Marriott, Gerard

2011-02-01

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

Total-reflection X-ray fluorescence studies of trace elements in biomedical samples

NASA Astrophysics Data System (ADS)

Kubala-Kukuś, A.; Braziewicz, J.; Pajek, M.

2004-08-01

Application of the total-reflection X-ray fluorescence (TXRF) analysis in the studies of trace element contents in biomedical samples is discussed in the following aspects: (i) a nature of trace element concentration distributions, (ii) censoring approach to the detection limits, and (iii) a comparison of two sets of censored data. The paper summarizes the recent results achieved in this topics, in particular, the lognormal, or more general logstable, nature of concentration distribution of trace elements, the random left-censoring and the Kaplan-Meier approach accounting for detection limits and, finally, the application of the logrank test to compare the censored concentrations measured for two groups. These new aspects, which are of importance for applications of the TXRF in different fields, are discussed here in the context of TXRF studies of trace element in various samples of medical interest.

Direct detection of RDX vapor using a conjugated polymer network.

PubMed

Gopalakrishnan, Deepti; Dichtel, William R

2013-06-05

1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) is a principal component of plastic explosives used in acts of terrorism and within improvised explosive devices, among others. Approaches to detect RDX compatible with remote, "stand-off" sampling that do not require preconcentration strategies, such as the swabs commonly employed in airports, will benefit military and civilian security. Such detection remains a significant challenge because RDX is 10(3) less volatile than 1,3,5-trinitrotoluene (TNT), corresponding to a parts-per-trillion vapor pressure under ambient conditions. Therefore, while fluorescence quenching of conjugated polymers is sufficiently sensitive to detect TNT vapors, RDX vapor detection is undemonstrated. Here we report a cross-linked phenylene vinylene polymer network whose fluorescence is quenched by trace amounts of RDX introduced from solution or the vapor phase. Fluorescence quenching is reduced, but remains significant, when partially degraded RDX is employed, suggesting that the polymer responds to RDX itself. The polymer network also responds to TNT and PETN similarly introduced from solution or the vapor phase. Pure solvents, volatile amines, and the outgassed vapors from lipstick or sunscreen do not quench polymer fluorescence. The established success of TNT sensors based on fluorescence quenching makes this a material of interest for real-world explosive sensors and will motivate further interest in cross-linked polymers and framework materials for sensing applications.

Preparation of an Efficient Ratiometric Fluorescent Nanoprobe (m-CDs@[Ru(bpy)3]2+) for Visual and Specific Detection of Hypochlorite on Site and in Living Cells.

PubMed

Zhan, Yuanjin; Luo, Fang; Guo, Longhua; Qiu, Bin; Lin, Yuhong; Li, Juan; Chen, Guonan; Lin, Zhenyu

2017-11-22

Hypochlorite (ClO - ) is one of the most important reactive oxygen species (ROS), which plays an important role in sustaining human innate immunity during microbial invasion. Moreover, ClO - is a powerful oxidizer for water treatment. The safety of drinking water is closely related to its content. Herein, m-phenylenediamine (mPD) is used as a precursor to prepare carbon dots (named m-CDs) with highly fluorescent quantum yield (31.58% in water), and our investigation shows that the strong fluorescent emission of m-CDs can be effectively quenched by ClO - . Based on these findings, we developed a novel fluorescent nanoprobe (m-CDs) for highly selective detection of ClO - . The linear range was from 0.05 to 7 μM (R 2 = 0.998), and the limit of detection (S/N = 3) was as low as 0.012 μM. Moreover, a portable agarose hydrogel solid matrix-based ratiometric fluorescent nanoprobe (m-CDs@[Ru(bpy) 3 ] 2+ ) sensor was subsequently developed for visual on-site detection of ClO - with the naked eyes under a UV lamp, suggesting its potential in practical application with low cost and excellent performance in water quality monitoring. Additionally, intracellular detection of exogenous ClO - was demonstrated via ratiometric imaging microscopy.

Visual and portable strategy for copper(II) detection based on a striplike poly(thymine)-caged and microwell-printed hydrogel.

PubMed

Qing, Zhihe; Mao, Zhengui; Qing, Taiping; He, Xiaoxiao; Zou, Zhen; He, Dinggeng; Shi, Hui; Huang, Jin; Liu, Jianbo; Wang, Kemin

2014-11-18

Due to its importance to develop strategies for copper(II) (Cu(2+)) detection, we here report a visual and portable strategy for Cu(2+) detection based on designing and using a strip-like hydrogel. The hydrogel is functionalized through caging poly(thymine) as probes, which can effectively template the formation of fluorescent copper nanoparticles (CuNPs) in the presence of the reductant (ascorbate) and Cu(2+). On the hydrogel's surface, uniform wells of microliter volume (microwells) are printed for sample-injection. When the injected sample is stained by Cu(2+), fluorescent CuNPs will be in situ templated by poly T in the hydrogel. With ultraviolet (UV) irradiation, the red fluorescence of CuNPs can be observed by naked-eye and recorded by a common camera without complicated instruments. Thus, the strategy integrates sample-injection, reaction and indication with fast signal response, providing an add-and-read manner for visual and portable detection of Cu(2+), as well as a strip-like strategy. Detection ability with a detectable minimum concentration of 20 μM and practically applicable properties have been demonstrated, such as resistance to environmental interference and good constancy, indicating that the strategy holds great potential and significance for popular detection of Cu(2+), especially in remote regions. We believe that the strip-like hydrogel-based methodology is also applicable to other targets by virtue of altering probes.

Clinical application of photodynamic medicine technology using light-emitting fluorescence imaging based on a specialized luminous source.

PubMed

Namikawa, Tsutomu; Fujisawa, Kazune; Munekage, Eri; Iwabu, Jun; Uemura, Sunao; Tsujii, Shigehiro; Maeda, Hiromichi; Kitagawa, Hiroyuki; Fukuhara, Hideo; Inoue, Keiji; Sato, Takayuki; Kobayashi, Michiya; Hanazaki, Kazuhiro

2018-04-04

The natural amino acid 5-aminolevulinic acid (ALA) is a protoporphyrin IX (PpIX) precursor and a new-generation photosensitive substance that accumulates specifically in cancer cells. When indocyanine green (ICG) is irradiated with near-infrared (NIR) light, it shifts to a higher energy state and emits infrared light with a longer wavelength than the irradiated NIR light. Photodynamic diagnosis (PDD) using ALA and ICG-based NIR fluorescence imaging has emerged as a new diagnostic technique. Specifically, in laparoscopic examinations for serosa-invading advanced gastric cancer, peritoneal metastases could be detected by ALA-PDD, but not by conventional visible-light imaging. The HyperEye Medical System (HEMS) can visualize ICG fluorescence as color images simultaneously projected with visible light in real time. This ICG fluorescence method is widely applicable, including for intraoperative identification of sentinel lymph nodes, visualization of blood vessels in organ resection, and blood flow evaluation during surgery. Fluorescence navigation by ALA-PDD and NIR using ICG imaging provides good visualization and detection of the target lesions that is not possible with the naked eye. We propose that this technique should be used in fundamental research on the relationship among cellular dynamics, metabolic enzymes, and tumor tissues, and to evaluate clinical efficacy and safety in multicenter cooperative clinical trials.

Enhanced fluorescence microscope and its application

NASA Astrophysics Data System (ADS)

Wang, Susheng; Li, Qin; Yu, Xin

1997-12-01

A high gain fluorescence microscope is developed to meet the needs in medical and biological research. By the help of an image intensifier with luminance gain of 4 by 104 the sensitivity of the system can achieve 10-6 1x level and be 104 times higher than ordinary fluorescence microscope. Ultra-weak fluorescence image can be detected by it. The concentration of fluorescent label and emitting light intensity of the system are decreased as much as possible, therefore, the natural environment of the detected call can be kept. The CCD image acquisition set-up controlled by computer obtains the quantitative data of each point according to the gray scale. The relation between luminous intensity and output of CCD is obtained by using a wide range weak photometry. So the system not only shows the image of ultra-weak fluorescence distribution but also gives the intensity of fluorescence of each point. Using this system, we obtained the images of distribution of hypocrellin A (HA) in Hela cell, the images of Hela cell being protected by antioxidant reagent Vit. E, SF and BHT. The images show that the digitized ultra-sensitive fluorescence microscope is a useful tool for medical and biological research.

Design of remote laser-induced fluorescence system's acquisition circuit

NASA Astrophysics Data System (ADS)

Wang, Guoqing; Lou, Yue; Wang, Ran; Yan, Debao; Li, Xin; Zhao, Xin; Chen, Dong; Zhao, Qi

2017-10-01

Laser-induced fluorescence system(LIfS) has been found its significant application in identifying one kind of substance from another by its properties even it's thimbleful, and becomes useful in plenty of fields. Many superior works have reported LIfS' theoretical analysis , designs and uses. However, the usual LIPS is always constructed in labs to detect matter quite closely, for the system using low-power laser as excitation source and charge coupled device (CCD) as detector. Promoting the detectivity of LIfS is of much concern to spread its application. Here, we take a high-energy narrow-pulse laser instead of commonly used continuous wave laser to operate sample, thus we can get strong fluorescent. Besides, photomultiplier (PMT) with high sensitivity is adopted in our system to detect extremely weak fluorescence after a long flight time from the sample to the detector. Another advantage in our system, as the fluorescence collected into spectroscopy, multiple wavelengths of light can be converted to the corresponding electrical signals with the linear array multichannel PMT. Therefore, at the cost of high-powered incentive and high-sensitive detector, a remote LIFS is get. In order to run this system, it is of importance to turn light signal to digital signal which can be processed by computer. The pulse width of fluorescence is deeply associated with excitation laser, at the nanosecond(ns) level, which has a high demand for acquisition circuit. We design an acquisition circuit including, I/V conversion circuit, amplifying circuit and peak-holding circuit. The simulation of circuit shows that peak-holding circuit can be one effective approach to reducing difficulty of acquisition circuit.

8-aminoquinoline functionalized silica nanoparticles: a fluorescent nanosensor for detection of divalent zinc in aqueous and in yeast cell suspension.

PubMed

Rastogi, Shiva K; Pal, Parul; Aston, D Eric; Bitterwolf, Thomas E; Branen, A Larry

2011-05-01

Zinc is one of the most important transition metal of physiological importance, existing primarily as a divalent cation. A number of sensors have been developed for Zn(II) detection. Here, we present a novel fluorescent nanosensor for Zn(II) detection using a derivative of 8-aminoquinoline (N-(quinolin-8-yl)-2-(3 (triethoxysilyl)propylamino)acetamide (QTEPA) grafted on silica nanoparticles (SiNPs). These functionalized SiNPs were used to demonstrate specific detection of Zn(II) in tris-HCl buffer (pH 7.22), in yeast cell (Saccharomyces cerevisiae) suspension, and in tap water. The silane QTEPA, SiNPs and final product were characterized using solution and solid state nuclear magnetic resonance, Fourier transform infrared, ultraviolet-visible absorption spectroscopy, transmission electron microscopy, elemental analysis, thermogravimetric techniques, and fluorescence spectroscopy. The nanosensor shows almost 2.8-fold fluorescence emission enhancement and about 55 nm red-shift upon excitation with 330 ± 5 nm wavelength in presence of 1 μM Zn(II) ions in tris-HCl (pH 7.22). The presence of other metal ions has no observable effect on the sensitivity and selectivity of nanosensor. This sensor selectively detects Zn(II) ions with submicromolar detection to a limit of 0.1 μM. The sensor shows good applicability in the determination of Zn(II) in tris-HCl buffer and yeast cell environment. Further, it shows enhancement in fluorescence intensity in tap water samples.

[Clinical utility of real-time fluorescent PCR for combined detection of anaplastic lymphoma kinase and c-ros oncogene 1 receptor tyrosine kinase in non-small cell lung cancer].

PubMed

Bai, D Y; Zhang, H P; Zhong, S; Suo, W H; Gao, D H; Ding, Y; Tu, J H

2016-12-23

Objective: To investigate the clinical application value of combined detection of ALK fusion gene and c-ros oncogene 1 receptor tyrosine kinase (ROS1) fusion gene in non-small cell lung cancer (NSCLC) using real-time fluorescent PCR. Methods: A kit for combined detection of ALK fusion gene and ROS1 fusion gene based on fluorescent PCR was used to simultaneously detect the two fusion genes in 302 cases of NSCLC specimens. The results were validated through Sanger sequencing. The consistency of the two detection methods was analyzed. Results: All 302 cases of NSCLC specimens were successfully analyzed through fluorescent PCR (302/302). 12 cases (4.0%) were found to contain ALK fusion gene, including 3 cases with ALK-M1, 3 with ALK-M2, 3 with ALK-M3, 1 with ALK-M4, and 2 with ALK-M6 fusion gene.12 cases (4.0%) were found to contain ROS1 fusion gene, including 1 case with ROS1-M7, 8 cases with ROS1-M8, 1 case with ROS1-M12, 1 case with ROS1-M14, and 1 case with double-positive ROS1-M3 and ROS1-M8 fusion genes. The total detection rate of ALK fusion gene and ROS1 fusion gene was 7.9% (24/302) and 278 cases showed to be negative for ALK fusion gene and ROS1 fusion gene. The successful detection rates for Sanger DNA sequencing were also 100%. The positive, negative and total coincidence rates obtained by real-time fluorescent PCR and by Sanger DNA sequencing were all 100%. Conclusions: The results of Sanger DNA sequencing demonstrate that the real-time fluorescent PCR assay is equally effective in detecting ALK and ROS1 fusion genes in NSCLC tissues. Furthermore, real-time fluorescent PCR assay can be used to detect trace ALK and ROS1 fusion gene simultaneously in tiny samples, and can save time and avoid repeated sampling. It is worthy of recommendation as a rapid and reliable detection technique.

Superiorities of time-correlated single-photon counting against standard fluorimetry in exploiting the potential of fluorochromized oligonucleotide probes for biomedical investigation

NASA Astrophysics Data System (ADS)

Lamperti, Marco; Nardo, Luca; Bondani, Maria

2015-05-01

Site-specific fluorescence-resonance-energy-transfer donor-acceptor dual-labelled oligonucleotide probes are widely used in state-of-art biotechnological applications. Such applications include their usage as primers in polymerase chain reaction. However, the steady-state fluorescence intensity signal emitted by these molecular tools strongly depends from the specificities of the probe conformation. For this reason, the information which can be reliably inferred by steady-state fluorimetry performed on such samples is forcedly confined to a semi-qualitative level. Namely, fluorescent emission is frequently used as ON/OFF indicator of the probe hybridization state, i.e. detection of fluorescence signals indicates either hybridization to or detachment from the template DNA of the probe. Nonetheless, a fully quantitative analysis of their fluorescence emission properties would disclose other exciting applications of dual-labelled probes in biosensing. Here we show how time-correlated single-photon counting can be applied to get rid of the technical limitations and interpretational ambiguities plaguing the intensity analysis, and to derive information on the template DNA reaching single-base.

Dual-color two-photon fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Berland, Keith M.

2001-04-01

Fluorescence correlation spectroscopy (FCS) is rapidly growing in popularity as a research tool in biological and biophysical research. Under favorable conditions, FCS measurements can produce an accurate characterization of the chemical, physical, and kinetic properties of a biological system. However, interpretation of FCS data quickly becomes complicated as the heterogeneity of a molecular system increases, as well as when there is significant non-stationery fluorescence background (e.g. intracellular autofluorescence). Use of multi-parameter correlation measurements is one promising approach that can improve the fidelity of FCS measurements in complex systems. In particular, the use of dual-color fluorescence assays, in which different interacting molecular species are labeled with unique fluorescent indicators, can "tune" the sensitivity of FCS measurements in favor of particular molecular species of interest, while simultaneously minimizing the contribution of other molecular species to the overall fluorescence correlation signal. Here we introduce the combined application of two-photon fluorescence excitation and dual-color cross-correlation analysis for detecting molecular interactions in solution. The use of two-photon excitation is particularly advantageous for dual-color FCS applications due to the uncomplicated optical alignment and the superior capabilities for intracellular applications. The theory of two-photon dual-color FCS is introduced, and initial results quantifying hybridization reactions between three independent single stranded DNA molecules are presented.

Photoinduced electron transfer between Fe(III) and adenosine triphosphate-BODIPY conjugates: Application to alkaline-phosphatase-linked immunoassay.

PubMed

Lin, Jia-Hui; Yang, Ya-Chun; Shih, Ya-Chen; Hung, Szu-Ying; Lu, Chi-Yu; Tseng, Wei-Lung

2016-03-15

Fluorescent boron dipyrromethene (BODIPY) analogs are often used as sensors for detecting various species because of their relatively high extinction coefficients, outstanding fluorescence quantum yields, photostability, and pH-independent fluorescence. However, there is little-to-no information in the literature that describes the use of BODIPY analogs for detecting alkaline phosphatase (ALP) activity and inhibition. This study discovered that the fluorescence of BODIPY-conjugated adenosine triphosphate (BODIPY-ATP) was quenched by Fe(III) ions through photoinduced electron transfer. The ALP-catalyzed hydrolysis of BODIPY-ATP resulted in the formation of BODIPY-adenosine and phosphate ions. The fluorescence of the generated BODIPY-adenosine was insensitive to the change in the concentration of Fe(III) ions. Thus, the Fe(III)-induced fluorescence quenching of BODIPY-ATP can be paired with its ALP-mediated dephosphorylation to design a turn-on fluorescence probe for ALP sensing. A method detection limit at a signal-to-noise ratio of 3 for ALP was estimated to be 0.02 units/L (~6 pM; 1 ng/mL). This probe was used for the screening of ALP inhibitors, including Na3VO4, imidazole, and arginine. Because ALP is widely used in enzyme-linked immunosorbent assays, the probe was coupled to an ALP-linked immunosorbent assay for the sensitive and selective detection of immunoglobulin G (IgG). The lowest detectable concentration for IgG in this system was 5 ng/mL. Compared with the use of 3,6-fluorescein diphosphate as a signal reporter in an ALP-linked immunosorbent assay, the proposed system provided comparable sensitivity, large linear range, and high stability over temperature and pH changes. Copyright © 2015 Elsevier B.V. All rights reserved.

Basic principles of fluorescence detection with use of 5-ALA

NASA Astrophysics Data System (ADS)

Baumgartner, Reinhold; Stepp, Herbert G.

2000-06-01

5-Aminolevulinic acid (5-ALA) has been proven to induce selective accumulation of flourescent Protoporphyrin IX (PPIX) in many types of malignant tissue. According to the target to treatment different routes of topical and systemical application of 5-ALA can be chosen. They include techniques like inhalation, installation and rinsing. For fluorescence detection a lamp based system have been developed in the laser-Forschungslabor in Munich together with Storz company. By skillful balancing of excitation filter centered around 400 nm and the observation filter with transmission above 450 nm images with high color contrast can be obtained. The universal application of the D-LIGHT could be demonstrated in different clinical disciplines like urology, neurosurgery, ENT clinic, gynecology and others.

Quantitative and qualitative 5-aminolevulinic acid–induced protoporphyrin IX fluorescence in skull base meningiomas

PubMed Central

Bekelis, Kimon; Valdés, Pablo A.; Erkmen, Kadir; Leblond, Frederic; Kim, Anthony; Wilson, Brian C.; Harris, Brent T.; Paulsen, Keith D.; Roberts, David W.

2011-01-01

Object Complete resection of skull base meningiomas provides patients with the best chance for a cure; however, surgery is frequently difficult given the proximity of lesions to vital structures, such as cranial nerves, major vessels, and venous sinuses. Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative assessment of protoporphyrin IX (PpIX) fluorescence following the exogenous administration of 5-aminolevulinic acid (ALA) has demonstrated utility in malignant glioma resection but limited use in meningiomas. Here the authors demonstrate the use of ALA-induced PpIX fluorescence guidance in resecting a skull base meningioma and elaborate on the advantages and disadvantages provided by both quantitative and qualitative fluorescence methodologies in skull base meningioma resection. Methods A 52-year-old patient with a sphenoid wing WHO Grade I meningioma underwent tumor resection as part of an institutional review board–approved prospective study of fluorescence-guided resection. A surgical microscope modified for fluorescence imaging was used for the qualitative assessment of visible fluorescence, and an intraoperative probe for in situ fluorescence detection was utilized for quantitative measurements of PpIX. The authors assessed the detection capabilities of both the qualitative and quantitative fluorescence approaches. Results The patient harboring a sphenoid wing meningioma with intraorbital extension underwent radical resection of the tumor with both visibly and nonvisibly fluorescent regions. The patient underwent a complete resection without any complications. Some areas of the tumor demonstrated visible fluorescence. The quantitative probe detected neoplastic tissue better than the qualitative modified surgical microscope. The intraoperative probe was particularly useful in areas that did not reveal visible fluorescence, and tissue from these areas was confirmed as tumor following histopathological analysis. Conclusions Fluorescence-guided resection may be a useful adjunct in the resection of skull base meningiomas. The use of a quantitative intraoperative probe to detect PpIX concentration allows more accurate determination of neoplastic tissue in meningiomas than visible fluorescence and is readily applicable in areas, such as the skull base, where complete resection is critical but difficult because of the vital structures surrounding the pathology. PMID:21529179

A new pyrene based highly sensitive fluorescence probe for copper(II) and fluoride with living cell application.

PubMed

Goswami, Shyamaprosad; Chakraborty, Shampa; Paul, Sima; Halder, Sandipan; Panja, Sukanya; Mukhopadhyay, Subhra Kanti

2014-05-21

A new pyrene based fluorescence probe has been synthesized for fluorogenic detection of Cu(2+) in acetonitrile-aqueous media (7 : 3 CH3CN-HEPES buffer, v/v, at pH 7.5) with bioimaging in both prokaryotic (Candida albicans cells) and eukaryotic (Tecoma stans pollen cells) living cells. The anion recognition properties of the sensor have also been studied in acetonitrile by fluorescence methods which show remarkable sensitivity toward fluoride over other anions examined.

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

PubMed Central

Guo, Nan; Cheung, Ka Wai; Wong, Hiu Tung; Ho, Derek

2014-01-01

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. PMID:25365460

Quantum dot conjugates in a sub-micrometer fluidic channel

DOEpatents

Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

2010-04-13

A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

Quantum dot conjugates in a sub-micrometer fluidic channel

DOEpatents

Stavis, Samuel M [Ithaca, NY; Edel, Joshua B [Brookline, MA; Samiee, Kevan T [Ithaca, NY; Craighead, Harold G [Ithaca, NY

2008-07-29

A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

Controllable synthesis of green and blue fluorescent carbon nanodots for pH and Cu(2+) sensing in living cells.

PubMed

Shi, Lihong; Li, Yanyan; Li, Xiaofeng; Zhao, Bo; Wen, Xiangping; Zhang, Guomei; Dong, Chuan; Shuang, Shaomin

2016-03-15

We report a controllable strategy for fabrication of green and blue fluorescent carbon nanodots (CDs), and demonstrate their applications for pH and Cu(2+) sensing in living cells. Green and blue fluorescent CDs have been synthesized by hydrothermal method and pyrolysis of leeks, respectively, providing an easy way for the production of CDs without the request of tedious synthetic methodology or the use of toxic/expensive solvents and starting materials. Green fluorescent CDs (G-CDs) exhibit high tolerance to pH values and external cations. Blue fluorescent CDs (B-CDs) can be applied to pH and Cu(2+) sensing. The linear range of Cu(2+) detection is 0.01-10.00 μM and the detection limit is 0.05 μM. For pH detection, there is a good linearity in the pH range of 3.5-10.0. The linear and rapid response of B-CDs to Cu(2+) and pH is valuable for Cu(2+) and pH sensing in living cells. Confocal fluorescent imaging of human cervical carcinoma cells indicates that B-CDs could visualize Cu(2+) and pH fluctuations in living cells with negligible autofluorescence. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid and sensitive detection of early esophageal squamous cell carcinoma with fluorescence probe targeting dipeptidylpeptidase IV

PubMed Central

Onoyama, Haruna; Kamiya, Mako; Kuriki, Yugo; Komatsu, Toru; Abe, Hiroyuki; Tsuji, Yosuke; Yagi, Koichi; Yamagata, Yukinori; Aikou, Susumu; Nishida, Masato; Mori, Kazuhiko; Yamashita, Hiroharu; Fujishiro, Mitsuhiro; Nomura, Sachiyo; Shimizu, Nobuyuki; Fukayama, Masashi; Koike, Kazuhiko; Urano, Yasuteru; Seto, Yasuyuki

2016-01-01

Early detection of esophageal squamous cell carcinoma (ESCC) is an important prognosticator, but is difficult to achieve by conventional endoscopy. Conventional lugol chromoendoscopy and equipment-based image-enhanced endoscopy, such as narrow-band imaging (NBI), have various practical limitations. Since fluorescence-based visualization is considered a promising approach, we aimed to develop an activatable fluorescence probe to visualize ESCCs. First, based on the fact that various aminopeptidase activities are elevated in cancer, we screened freshly resected specimens from patients with a series of aminopeptidase-activatable fluorescence probes. The results indicated that dipeptidylpeptidase IV (DPP-IV) is specifically activated in ESCCs, and would be a suitable molecular target for detection of esophageal cancer. Therefore, we designed, synthesized and characterized a series of DPP-IV-activatable fluorescence probes. When the selected probe was topically sprayed onto endoscopic submucosal dissection (ESD) or surgical specimens, tumors were visualized within 5 min, and when the probe was sprayed on biopsy samples, the sensitivity, specificity and accuracy reached 96.9%, 85.7% and 90.5%. We believe that DPP-IV-targeted activatable fluorescence probes are practically translatable as convenient tools for clinical application to enable rapid and accurate diagnosis of early esophageal cancer during endoscopic or surgical procedures. PMID:27245876

Characterizing the Intrinsic Fluorescence Properties of Historical Painting Materials: The Case Study of a Sixteenth-Century Mesoamerican Manuscript.

PubMed

Pottier, Fabien; Michelin, Anne; Andraud, Christine; Goubard, Fabrice; Lavédrine, Bertrand

2018-04-01

Ultraviolet visible (UV-Vis) fluorescence spectroscopy is widely used to study polychrome objects and can help to identify the nature of certain materials when they present specific fluorescent properties. However, given the complexity of the stratified and heterogeneous materials under study, the characterization of an intrinsic fluorescence related to a given constituent (a pigment or a binder composing a paint layer for example) is not straightforward, and the recorded raw data need to be corrected for a number of effects that can influence the detected spectral distribution. The application of standard correction procedures to experimental fluorescence data gathered on the polychromatic surface of the Codex Borbonicus, a 16th-century Aztec manuscript, is described. The results are confronted to an alternate new methodology that is based on the hypothesis of transparent non-scattering paint layers. This second approach allows to establish more clearly the material origin of the detected emission and to discriminate apparent fluorescence (emitted by the substrate and transmitted through the paint layers) from actual intrinsic emission generated by the coloring materials under study. The results show that most of the various emission profiles detected in the paint layers of the manuscript actually originate from a unique fluorophore (composing the substrate) and should not be used to characterize the coloring materials.

Label-free fluorescence strategy for sensitive detection of adenosine triphosphate using a loop DNA probe with low background noise.

PubMed

Lin, Chunshui; Cai, Zhixiong; Wang, Yiru; Zhu, Zhi; Yang, Chaoyong James; Chen, Xi

2014-07-15

A simple, rapid, label-free, and ultrasensitive fluorescence strategy for adenosine triphosphate (ATP) detection was developed using a loop DNA probe with low background noise. In this strategy, a loop DNA probe, which is the substrate for both ligation and digestion enzyme reaction, was designed. SYBR green I (SG I), a double-stranded specific dye, was applied for the readout fluorescence signal. Exonuclease I (Exo I) and exonuclease III (Exo III), sequence-independent nucleases, were selected to digest the loop DNA probe in order to minimize the background fluorescence signal. As a result, in the absence of ATP, the loop DNA was completely digested by Exo I and Exo III, leading to low background fluorescence owing to the weak electrostatic interaction between SG I and mononucleotides. On the other hand, ATP induced the ligation of the nicking site, and the sealed loop DNA resisted the digestion of Exo I and ExoIII, resulting in a remarkable increase of fluorescence response. Upon background noise reduction, the sensitivity of the ATP determination was improved significantly, and the detection limitation was found to be 1.2 pM, which is much lower than that in almost all the previously reported methods. This strategy has promise for wide application in the determination of ATP.

Gaseous phase ion detection method based on laser-induced fluorescence for ion mobility spectrometer

NASA Astrophysics Data System (ADS)

Guo, Kaitai; Ni, Kai; Ou, Guangli; Zhang, Xiaoguo; Yu, Quan; Qian, Xiang; Wang, Xiaohao

2015-08-01

Ion mobility spectrometry (IMS) is widely used in the field of chemical composition analysis. Faraday cup is the most classical method to detect ions for IMS in the atmospheric pressure. However, the performance of Faraday plate was limited by many kinds of factors, including interfering electromagnetic waves, thermal(Johnson) noise, induced current , gain bandwidth product, etc. There is a theoretical limit in detection of ions at ambient condition which is approximately 106 ions per second. In this paper, we introduced a novel way using laser-induced fluorescence (LIF) to bypass the limitation of Faraday plate. Fluorescent ions which were selected by IMS get excited when they fly through the laser excitation area. The fluorescence emitted by the excited ions was captured exponentially and amplified through proper optoelectronic system. Rhodamine 6G (R6G) was selected as the fluorochrome for the reason that excitation wavelength, emission wavelength, and fluorescence quantum yield were more appropriate than others. An orthometric light path is designed to eliminate the adverse impact which was caused by induced laser. The experiment result shows that a fluorescence signal from the sample ions of the IMS could be observed. Compared with Faraday plate, the LIF-IMS may find a potential application in more system at the atmosphere condition.

Methods and kits for nucleic acid analysis using fluorescence resonance energy transfer

DOEpatents

Kwok, Pui-Yan; Chen, Xiangning

1999-01-01

A method for detecting the presence of a target nucleotide or sequence of nucleotides in a nucleic acid is disclosed. The method is comprised of forming an oligonucleotide labeled with two fluorophores on the nucleic acid target site. The doubly labeled oligonucleotide is formed by addition of a singly labeled dideoxynucleoside triphosphate to a singly labeled polynucleotide or by ligation of two singly labeled polynucleotides. Detection of fluorescence resonance energy transfer upon denaturation indicates the presence of the target. Kits are also provided. The method is particularly applicable to genotyping.

Chemical probes for analysis of carbonylated proteins: a review

PubMed Central

Yan, Liang-Jun; Forster, Michael J.

2010-01-01

Protein carbonylation is a major form of protein oxidation and is widely used as an indicator of oxidative stress. Carbonyl groups do not have distinguishing UV or visible, spectrophotometric absorbance/fluorescence characteristics and thus their detection and quantification can only be achieved using specific chemical probes. In this paper, we review the advantages and disadvantages of several chemical probes that have been and are still being used for protein carbonyl analysis. These probes include 2, 4-dinitrophenylhydazine (DNPH), tritiated sodium borohydride ([3H]NaBH4), biotin-containing probes, and fluorescence probes. As our discussions lean toward gel-based approaches, utilizations of these probes in 2D gel-based proteomic analysis of carbonylated proteins are illustrated where applicable. Analysis of carbonylated proteins by ELISA, immunofluorescent imaging, near infrared fluorescence detection, and gel-free proteomic approaches are also discussed where appropriate. Additionally, potential applications of blue native gel electrophoresis as a tool for first dimensional separation in 2D gel-based analysis of carbonylated proteins are discussed as well. PMID:20732835

Synthesis and sensing integration: A novel enzymatic reaction modulated Nanoclusters Beacon (NCB) "Illumination" strategy for label-free biosensing and logic gate operation.

PubMed

Hong, Lu; Zhou, Fu; Wang, Guangfeng; Zhang, Xiaojun

2016-12-15

A novel fluorescent label-free "turn-on" NAD(+) and adenosine triphosphate (ATP) biosensing strategy is proposed by fully exploiting ligation triggered Nanocluster Beacon (NCB). In the presence of the target, the split NCB was brought to intact, which brought the C-rich sequence and enhancer sequence in close proximity resulting in the lightening of dark DNA/AgNCs ("On" mode). Further application was presented for logic gate operation and aptasensor construction. The feasibility was investigated by Ultraviolet-visible spectroscopy (UV-vis), Fluorescence, lifetime and High Resolution Transmission Electron Microscopy (HRTEM) etc. The strategy displayed good performance in the detection of NAD(+) and ATP, with the detection limit of 0.002nM and 0.001mM, the linear range of 10-1000nM and 0.003-0.01mM, respectively. Due to the DNA/AgNCs as fluorescence reporter, the completely label-free fluorescent strategy boasts the features of simplicity and low cost, and showing little reliance on the sensing environment. Meanwhile, the regulation by overhang G-rich sequence not relying on Förster energy transfer quenching manifests the high signal-to-background ratios (S/B ratios). This method not only provided a simple, economical and reliable fluorescent NAD(+) assay but also explored a flexible G-rich sequence regulated NCB probe for the fluorescent biosensors. Furthermore, this sensing mode was expanded to the application of a logic gate design, which exhibited a high performance for not only versatile biosensors construction but also for molecular computing application. Copyright © 2016 Elsevier B.V. All rights reserved.

Chlorophyll fluorescence emission as a reporter on cold tolerance in Arabidopsis thaliana accessions

PubMed Central

Mishra, Anamika; Höermiller, Imke I; Heyer, Arnd G; Nedbal, Ladislav

2011-01-01

Non-invasive, high-throughput screening methods are valuable tools in breeding for abiotic stress tolerance in plants. Optical signals such as chlorophyll fluorescence emission can be instrumental in developing new screening techniques. In order to examine the potential of chlorophyll fluorescence to reveal plant tolerance to low temperatures, we used a collection of nine Arabidopsis thaliana accessions and compared their fluorescence features with cold tolerance quantified by the well established electrolyte leakage method on detached leaves. We found that, during progressive cooling, the minimal chlorophyll fluorescence emission rose strongly and that this rise was highly dependent on the cold tolerance of the accessions. Maximum quantum yield of PSII photochemistry and steady state fluorescence normalized to minimal fluorescence were also highly correlated to the cold tolerance measured by the electrolyte leakage method. In order to further increase the capacity of the fluorescence detection to reveal the low temperature tolerance, we applied combinatorial imaging that employs plant classification based on multiple fluorescence features. We found that this method, by including the resolving power of several fluorescence features, can be well employed to detect cold tolerance already at mild sub-zero temperatures. Therefore, there is no need to freeze the screened plants to the largely damaging temperatures of around −15°C. This, together with the method's easy applicability, represents a major advantage of the fluorescence technique over the conventional electrolyte leakage method. PMID:21427532

Design and synthesis of a novel lanthanide fluorescent probe (TbIII-dtpa-bis(2,6-diaminopurine)) and its application to the detection of uric acid in urine sample.

PubMed

Yang, Fan; Yu, Zhiyue; Li, Xinyi; Ren, Peipei; Liu, Guanhong; Song, Youtao; Wang, Jun

2018-06-03

In this study, a novel fluorescent probe, Tb III -dtpa-bis(2,6-diaminopurine) (Tb-dtpa-bdap), is designed based on the principle of complementary base pairing and synthesized for uric acid detection. The synthesized fluorescent probe is characterized by 1 H NMR, 13 C NMR, infra-red (IR) spectrum and ultraviolet-visible (UV-vis) spectra. It is found that the fluorescence of Tb-dtpa-bdap solution can be quenched obviously in the presence of uric acid. The affecting factors, including solution acidity, uric acid concentration and interfering substances, on the detection of uric acid using this probe are examined. Under optimized conditions, the fluorescence intensities of Tb-dtpa-bdap solution towards different uric acid concentrations show a linear response in the range from 1.00 × 10 -5  mol·L -1 to 5.00 × 10 -5  mol·L -1 with a linear correlation coefficient (R 2 ) of 0.9877. And the obtained limit of detection (LOD) is about 5.80 × 10 -6  mol·L -1 , which is lower than the level of uric acid in actual urine. The mechanism on the detection of uric acid by using Tb-dtpa-bdap is inferred from the experimental results. The facts demonstrate that the proposed fluorescent probe can be successfully applied for the determination of uric acid in human urine samples. Copyright © 2018 Elsevier B.V. All rights reserved.

A fluorescent graphitic carbon nitride nanosheet biosensor for highly sensitive, label-free detection of alkaline phosphatase.

PubMed

Xiang, Mei-Hao; Liu, Jin-Wen; Li, Na; Tang, Hao; Yu, Ru-Qin; Jiang, Jian-Hui

2016-02-28

Graphitic C3N4 (g-C3N4) nanosheets provide an attractive option for bioprobes and bioimaging applications. Utilizing highly fluorescent and water-dispersible ultrathin g-C3N4 nanosheets, a highly sensitive, selective and label-free biosensor has been developed for ALP detection for the first time. The developed approach utilizes a natural substrate of ALP in biological systems and thus affords very high catalytic efficiency. This novel biosensor is demonstrated to enable quantitative analysis of ALP in a wide range from 0.1 to 1000 U L(-1) with a low detection limit of 0.08 U L(-1), which is among the most sensitive assays for ALP. It is expected that the developed method may provide a low-cost, convenient, rapid and highly sensitive platform for ALP-based clinical diagnostics and biomedical applications.

Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana.

PubMed

Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

2015-01-01

The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII).

Lunisolar tidal force and its relationship to chlorophyll fluorescence in Arabidopsis thaliana

PubMed Central

Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

2015-01-01

The yield of chlorophyll fluorescence Ft was measured in leaves of Arabidopsis thaliana over periods of several days under conditions of continuous illumination (LL) without the application of saturating light pulses. After linearization of the time series of the chlorophyll fluorescence yield (ΔFt), oscillations became apparent with periodicities in the circatidal range. Alignments of these linearized time series ΔFt with the lunisolar tidal acceleration revealed high degrees of synchrony and phase congruence. Similar congruence with the lunisolar tide was obtained with the linearized quantum yield of PSII (ΔФII), recorded after application of saturating light pulses. These findings strongly suggest that there is an exogenous timekeeper which is a stimulus for the oscillations detected in both the linearized yield of chlorophyll fluorescence (ΔFt) and the linearized quantum yield of PSII (ΔФII). PMID:26376108

Fluorescent probes in biology and medicine: measurement of intracellular pH values in individual cells

NASA Astrophysics Data System (ADS)

Slavik, Jan; Cimprich, Petr; Gregor, Martin; Smetana, Karel, Jr.

1997-12-01

The application possibilities of fluorescent probes have increased dramatically in the last few years. The main areas are as follows (Slavik, 1994, 1996, 1998). Intracellular ionic cell composition: There are selective ion-sensitive dyes for H+, Ca2+, Mg2+, K+, Na+, Fe3+, Cl-, Zn2+, Cd2+, Hg2+, Pb2+, Ba2+, La3+. Membrane potential: Using the so-called slow (Nernstian dyes) or electrochromic dyes one can assess the value of the transmembrane potential. Membrane fluidity: Fluorescent probes inform about the freedom of rotational and translational movement of membrane proteins and lipids. Selective labeling: Almost any object of interest inside the cell or on its surface can be selectively fluorescently labeled. There are dyes specific for DNA, RNA, oligonucleotides (FISH), Golgi, endoplasmic reticulum, mitochondria, vacuoles, cytoskeleton, etc. Using fluorescent dyes specific receptors may be localized, their conformational changes followed and the polarity of corresponding binding sites accessed. The endocytic pathway may be followed, enzymes and their local enzymatic activity localized. For really selective labeling fluorescent labeled antibodies exist. Imaging: One of the main advantages of fluorescence imaging is its versatility. It allow choice among ratio imaging in excitation, ratio imaging in emission and lifetime imaging. These approaches can be applied to both the classical wide-field fluorescence microscopy and to the laser confocal fluorescence microscopy, one day possibly to the scanning near field optical microscopy. Simultaneous application of several fluorescent dyes: The technical progress in both excitation sources and in detectors allows to extend the excitation deeper in the blue and ultraviolet side and the detection further in the NIR and IR. Consequently, up to 6 peaks in excitation and up to 6 peaks in emission can be followed without any substantial difficulties. Application of dyes such with longer fluorescence lifetimes such as rare earth dyes gives chance for the separated detection of another six peak pairs. The literature data on simultaneous applications of several fluorescent dyes are rare, usually it is only pH and calcium, pH and membrane potential or pH and cytoskeleton changes that are mentioned. Nevertheless, I am sure that in the near future it will be quite common to employ several fluorescent dyes simultaneously. So, in a few years, you may expect to be comfortably seated in an armchair in front of the monitor screen, sip your coffee and follow simultaneously several physiological parameters trying to find out new relations among them. In this respect the potential of fluorescent probes is unsurpassed if you just recall only the discovery of calcium waves and calcium spikes during the past years.

Hemoglobin detection using carbon dots as a fluorescence probe.

PubMed

Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid

2015-09-15

Herein, we have described the application of high fluorescent carbon dots (CDs) without any surface modification as a simple and fast responding fluorescence probe for sensitive and selective determination of hemoglobin (Hb) in the presence of H2O2. Although Hb itself was able to quench the fluorescence of CDs, based on the inner filter effect (IFE) of the protein that affects both excitation and emission spectra of CDs, the presence of H2O2 resulted in further improvement of the sensitivity of Hb detection. The assay is based on the reaction of Hb with H2O2 that generates reactive oxygen species including hydroxyl (OH•) and superoxide (O2(•-)) radicals under heme degradation and/or iron release from Hb and the subsequent reaction of hydroxyl radicals, as strong oxidizing agents, with CDs resulting in high fluorescence quenching. The proposed probe was used for determination of Hb in concentration range of 1-100 nM with a detection limit of 0.4 nM. The method was successfully applied to the determination of Hb in human blood samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel "Turn-On" fluorescent probe for F(-) detection in aqueous solution and its application in live-cell imaging.

PubMed

Xu, Jian; Sun, Shaobo; Li, Qian; Yue, Ying; Li, Yingdong; Shao, Shijun

2014-11-07

A novel probe incorporating quaternized 4-pyridinium group into a BODIPY molecule was synthesized and studied for the selective detection of fluoride ions (F(-)) in aqueous solution. The design was based on a fluoride-specific desilylation reaction and the "Turn-On" fluorescent response of probe 1 to F(-) was ascribed to the inhibition of photoinduced electron transfer (PET) process. The probe displayed many desired properties such as high specificity, appreciable solubility, desirable response time and low toxicity to mammalian cells. There was a good linearity between the fluorescence intensity and the concentrations of F(-) in the range of 0.1-1mM with a detection limit of 0.02 mM. The sensing mechanism was confirmed by the NMR, electrospray ionization mass spectrum, optical spectroscopy and the mechanism of "Turn-On" fluorescent response was also determinated by a density functional theory (DFT) calculation using Gaussian 03 program. Moreover, the probe was successfully applied for the fluorescence imaging of F(-) in human epithelial lung cancer (A549) cells and alveolar type II (ATII) cells under physiological conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Quaternized magnetic nanoparticles-fluorescent polymer system for detection and identification of bacteria.

PubMed

Wan, Yi; Sun, Yan; Qi, Peng; Wang, Peng; Zhang, Dun

2014-05-15

Nanomaterial-based 'chemical nose' sensor with sufficient sensing specificity is a useful analytical tool for the detection of toxicologically important substances in complicated biological systems. A sensor array containing three quaternized magnetic nanoparticles (q-MNPs)-fluorescent polymer systems has been designed to identify and quantify bacteria. The bacterial cell membranes disrupt the q-MNP-fluorescent polymer, generating unique fluorescence response array. The response intensity of the array is dependent on the level of displacement determined by the relative q-MNP-fluorescent polymer binding strength and bacteria cells-MNP interaction. These characteristic responses show a highly repeatable bacteria cells and can be differentiated by linear discriminant analysis (LDA). Based on the array response matrix from LDA, our approach has been used to measure bacteria with an accuracy of 87.5% for 10(7) cfu mL(-1) within 20 min. Combined with UV-vis measurement, the method can be successfully performed to identify and detect eight different pathogen samples with an accuracy of 96.8%. The measurement system has a potential for further applications and provides a facile and simple method for the rapid analysis of protein, DNA, and pathogens. Copyright © 2013 Elsevier B.V. All rights reserved.

A novel fluorescent probe based on rhodamine hydrazone derivatives bearing a thiophene group for Al³⁺.

PubMed

Li, Meng-xiao; Zhang, Xia; Fan, Yu-hua; Bi, Cai-feng

2016-05-01

In the present work, a novel 5-methyl-thiophene-carbaldehyde-functionalized rhodamine 6G Schiff base (RA) was designed and easily prepared as an Al(3+) fluorescent and colorimetric probe, which could selectively and sensitively detect Al(3+) by showing enhanced fluorescence emission. Meanwhile distinct color variation from colorless to pink also provided 'naked eye' detection of Al(3+), due to the ring spirolactam opening of the rhodamine derivative. Other metal ions (including K(+), Mg(2+), Na(+), Ba(2+), Mn(2+), Cd(2+), Fe(2+), Ni(2+), Pb(2+), Zn(2+), Hg(2+), Co(2+), Li(+), Sr(2+) and Cu(2+)) could only induce limited interference. The detection limit of the fluorescent probe was estimated to be 4.17 × 10(-6) M, the binding constant of the RA-Al(3+) complex was 1.4 × 10(6)  M(-1). Moreover, this fluorescent probe RA possessed high reversibility. As aluminum is a ubiquitous metal in nature and plays vital roles in many biological processes, this chemosensor could be explored for biological study applications. Copyright © 2015 John Wiley & Sons, Ltd.

Trimodal color-fluorescence-polarization endoscopy aided by a tumor selective molecular probe accurately detects flat lesions in colitis-associated cancer

NASA Astrophysics Data System (ADS)

Charanya, Tauseef; York, Timothy; Bloch, Sharon; Sudlow, Gail; Liang, Kexian; Garcia, Missael; Akers, Walter J.; Rubin, Deborah; Gruev, Viktor; Achilefu, Samuel

2014-12-01

Colitis-associated cancer (CAC) arises from premalignant flat lesions of the colon, which are difficult to detect with current endoscopic screening approaches. We have developed a complementary fluorescence and polarization reporting strategy that combines the unique biochemical and physical properties of dysplasia and cancer for real-time detection of these lesions. Using azoxymethane-dextran sodium sulfate (AOM-DSS) treated mice, which recapitulates human CAC and dysplasia, we show that an octapeptide labeled with a near-infrared (NIR) fluorescent dye selectively identified all precancerous and cancerous lesions. A new thermoresponsive sol-gel formulation allowed topical application of the molecular probe during endoscopy. This method yielded high contrast-to-noise ratios (CNR) between adenomatous tumors (20.6±1.65) and flat lesions (12.1±1.03) and surrounding uninvolved colon tissue versus CNR of inflamed tissues (1.62±0.41). Incorporation of nanowire-filtered polarization imaging into NIR fluorescence endoscopy shows a high depolarization contrast in both adenomatous tumors and flat lesions in CAC, reflecting compromised structural integrity of these tissues. Together, the real-time polarization imaging provides real-time validation of suspicious colon tissue highlighted by molecular fluorescence endoscopy.

Smart coumarin-tagged imprinted polymers for the rapid detection of tamoxifen.

PubMed

Ray, Judith V; Mirata, Fosca; Pérollier, Celine; Arotcarena, Michel; Bayoudh, Sami; Resmini, Marina

2016-03-01

A signalling molecularly imprinted polymer was synthesised for easy detection of tamoxifen and its metabolites. 6-Vinylcoumarin-4-carboxylic acid (VCC) was synthesised from 4-bromophenol to give a fluorescent monomer, designed to switch off upon binding of tamoxifen. Clomiphene, a chlorinated analogue, was used as the template for the imprinting, and its ability to quench the coumarin fluorescence when used in a 1:1 ratio was demonstrated. Tamoxifen and 4-hydroxytamoxifen were also shown to quench coumarin fluorescence. Imprinted and non-imprinted polymers were synthesised using VCC, methacrylic acid as a backbone monomer and ethylene glycol dimethacrylate as cross-linker, and were ground and sieved to particle sizes ranging between 45 and 25 μm. Rebinding experiments demonstrate that the imprinted polymer shows very strong affinity for both clomiphene and tamoxifen, while the non-imprinted polymer shows negligible rebinding. The fluorescence of the imprinted polymer is quenched by clomiphene, tamoxifen and 4-hydroxytamoxifen. The switch off in fluorescence of the imprinted polymer under these conditions could also be detected under a UV lamp with the naked eye, making this matrix suitable for applications when coupled with a sample preparation system.

Fluorescent trimethyl-substituted naphthyridine as a label-free signal reporter for one-step and highly sensitive fluorescent detection of DNA in serum samples.

PubMed

Wang, Jiamian; Wang, Xiuyun; Wu, Shuo; Che, Ruping; Luo, Pinchen; Meng, Changgong

2017-01-15

A facile label-free sensing method is developed for the one-step and highly sensitive fluorescent detection of DNA, which couples the specific C-C mismatch bonding and fluorescent quenching property of a trimethyl-substituted naphthyridine dye (ATMND) with the exonuclease III (Exo III) assisted cascade target recycling amplification strategy. In the absence of target DNA, the DNA hairpin probe with a C-C mismatch in the stem and more than 4 bases overhung at the 3' terminus could entrap and quench the fluorescence of ATMND and resist the digestion of Exo III, thus showing a low fluorescence background. In the presence of the target, however, the hybridization event between the two protruding segments and the target triggers the digestion reaction of Exo III, recycles the initial target, and simultaneously releases both the secondary target analogue and the ATMND caged in the stem. The released initial and secondary targets take part in another cycle of digestion, thus leading to the release of a huge amount of free ATMND for signal transducing. Based on the fluorescence recovery, the as-proposed label-free fluorescent sensing strategy shows very good analytical performances towards DNA detection, such as a wide linear range from 10pM to 1μM, a low limit of detection of 6pM, good selectivity, and a facile one-step operation at room temperature. Practical sample analysis in serum samples indicates the method has good precision and accuracy, which may thus have application potentials for point-of-care screening of DNA in complex clinical and environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Scanning Fiber Endoscope Improves Detection of 5-Aminolevulinic Acid-Induced Protoporphyrin IX Fluorescence at the Boundary of Infiltrative Glioma.

PubMed

Belykh, Evgenii; Miller, Eric J; Hu, Danying; Martirosyan, Nikolay L; Woolf, Eric C; Scheck, Adrienne C; Byvaltsev, Vadim A; Nakaji, Peter; Nelson, Leonard Y; Seibel, Eric J; Preul, Mark C

2018-05-01

Fluorescence-guided surgery with protoporphyrin IX (PpIX) as a photodiagnostic marker is gaining acceptance for resection of malignant gliomas. Current wide-field imaging technologies do not have sufficient sensitivity to detect low PpIX concentrations. We evaluated a scanning fiber endoscope (SFE) for detection of PpIX fluorescence in gliomas and compared it to an operating microscope (OPMI) equipped with a fluorescence module and to a benchtop confocal laser scanning microscope (CLSM). 5-Aminolevulinic acid-induced PpIX fluorescence was assessed in GL261-Luc2 cells in vitro and in vivo after implantation in mouse brains, at an invading glioma growth stage, simulating residual tumor. Intraoperative fluorescence of high and low PpIX concentrations in normal brain and tumor regions with SFE, OPMI, CLSM, and histopathology were compared. SFE imaging of PpIX correlated to CLSM at the cellular level. PpIX accumulated in normal brain cells but significantly less than in glioma cells. SFE was more sensitive to accumulated PpIX in fluorescent brain areas than OPMI (P < 0.01) and dramatically increased imaging time (>6×) before tumor-to-background contrast was diminished because of photobleaching. SFE provides new endoscopic capabilities to view PpIX-fluorescing tumor regions at cellular resolution. SFE may allow accurate imaging of 5-aminolevulinic acid labeling of gliomas and other tumor types when current detection techniques have failed to provide reliable visualization. SFE was significantly more sensitive than OPMI to low PpIX concentrations, which is relevant to identifying the leading edge or metastasizing cells of malignant glioma or to treating low-grade gliomas. This new application has the potential to benefit surgical outcomes. Copyright © 2018 Elsevier Inc. All rights reserved.

Magnetic luminescent nanoparticles as internal calibration for an immunoassay for ricin

NASA Astrophysics Data System (ADS)

Dosev, Dosi; Nichkova, Mikaela; Ma, Zhi-Ya; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

2008-02-01

Fluorescence techniques rely on measurement of relative fluorescence units and require calibration to obtain reliable and comparable quantitative data. Fluorescent immunoassays are a very sensitive and convenient method of choice for rapid detection of biotoxins, such as ricin. Here we present the application of magnetic luminescent nanoparticles (MLNPs) with a magnetic core of Fe 3O 4 and a fluorescent shell of Eu:Gd IIO 3 as carriers for a nanobead-immunoassay for the detection of ricin with internal calibration. A sandwich immunoassay for ricin was performed on the surface of the MLNPs. The particles were functionalized with capture polyclonal antibodies. Anti-ricin antibodies labeled with Alexa Fluor dye were used as the detecting antibodies. After magnetic extraction, the amount of ricin bound to the particle surface was quantified and related to the fluorescence signal of the nanoparticles. In this new platform, the MLNPs have three main functions: (1) a probe for the specific extraction of the target analyte from the sample; (2) a carrier in the quantitative immunoassay with magnetic separation; and (3) an internal standard in the fluorescence measurement of the dye reporter. The MLNPs serve as an internal control for the total analysis including extraction and assay performance. This approach eliminates the experimental error inherent in particle extraction and measurement of absolute organic dye fluorescence intensities. All fluorescent measurements were performed in a microplate reader. The standard curve for ricin had a dynamic range from 20 ng/ml to 100 μg/ml with a detection limit of 5 ng/ml. The configuration that has been developed can be easily adapted to a high throughput miniaturized system.

Luminescent Quantum Dots as Ultrasensitive Biological Labels

NASA Astrophysics Data System (ADS)

Nie, Shuming

2000-03-01

Highly luminescent semiconductor quantum dots have been covalently coupled to biological molecules for use in ultrasensitive biological detection. This new class of luminescent labels is considerably brighter and more resistant againt photobleaching in comparison with organic dyes. Quantum dots labeled with the protein transferrin undergo receptor-mediated endocytosis (RME) in cultured HeLa cells, and those dots that were conjugated to immunomolecules recognize specific antibodies or antigens. In addition, we show that DNA functionalized quantum dots can be used to target specific genes by hybridization. We expect that quantum dot bioconjugates will have a broad range of biological applications, such as ligand-receptor interactions, real-time monitoring of molecular trafficking inside living cells, multicolor fluorescence in-situ hybridization (FISH), high-sensitivity detection in miniaturized devices (e.g., DNA chips), and fluorescent tagging of combinatorial chemical libraries. A potential clinical application is the use of quantum dots for ultrasensitive viral RNA detection, in which as low as 100 copies of hepatitis C and HIV viruses per ml blood should be detected.

Near-Membrane Refractometry Using Supercritical Angle Fluorescence.

PubMed

Brunstein, Maia; Roy, Lopamudra; Oheim, Martin

2017-05-09

Total internal reflection fluorescence (TIRF) microscopy and its variants are key technologies for visualizing the dynamics of single molecules or organelles in live cells. Yet truly quantitative TIRF remains problematic. One unknown hampering the interpretation of evanescent-wave excited fluorescence intensities is the undetermined cell refractive index (RI). Here, we use a combination of TIRF excitation and supercritical angle fluorescence emission detection to directly measure the average RI in the "footprint" region of the cell during image acquisition. Our RI measurement is based on the determination on a back-focal plane image of the critical angle separating evanescent and far-field fluorescence emission components. We validate our method by imaging mouse embryonic fibroblasts and BON cells. By targeting various dyes and fluorescent-protein chimeras to vesicles, the plasma membrane, as well as mitochondria and the endoplasmic reticulum, we demonstrate local RI measurements with subcellular resolution on a standard TIRF microscope, with a removable Bertrand lens as the only modification. Our technique has important applications for imaging axial vesicle dynamics and the mitochondrial energy state or detecting metabolically more active cancer cells. Copyright © 2017. Published by Elsevier Inc.

A facile fluorescent "turn-off" method for sensing paraquat based on pyranine-paraquat interaction

NASA Astrophysics Data System (ADS)

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.

Fluorescent quenching-based quantitative detection of specific DNA/RNA using a BODIPY® FL-labeled probe or primer

PubMed Central

Kurata, Shinya; Kanagawa, Takahiro; Yamada, Kazutaka; Torimura, Masaki; Yokomaku, Toyokazu; Kamagata, Yoichi; Kurane, Ryuichiro

2001-01-01

We have developed a simple method for the quantitative detection of specific DNA or RNA molecules based on the finding that BODIPY® FL fluorescence was quenched by its interaction with a uniquely positioned guanine. This approach makes use of an oligonucleotide probe or primer containing a BODIPY® FL-modified cytosine at its 5′-end. When such a probe was hybridized with a target DNA, its fluorescence was quenched by the guanine in the target, complementary to the modified cytosine, and the quench rate was proportional to the amount of target DNA. This widely applicable technique will be used directly with larger samples or in conjunction with the polymerase chain reaction to quantify small DNA samples. PMID:11239011

Ratiometric, visual, dual-signal fluorescent sensing and imaging of pH/copper ions in real samples based on carbon dots-fluorescein isothiocyanate composites.

PubMed

Zhu, Xinxin; Jin, Hui; Gao, Cuili; Gui, Rijun; Wang, Zonghua

2017-01-01

In this article, a facile aqueous synthesis of carbon dots (CDs) was developed by using natural kelp as a new carbon source. Through hydrothermal carbonization of kelp juice, fluorescent CDs were prepared and the CDs' surface was modified with polyethylenimine (PEI). The PEI-modified CDs were conjugated with fluorescein isothiocyanate (FITC) to fabricate CDs-FITC composites. To exploit broad applications, the CDs-FITC composites were developed as fluorescent sensing or imaging platforms of pH and Cu 2+ . Analytical performances of the composites-based fluorescence (FL) sensors were evaluated, including visual FL imaging of pH in glass bottle, ratiometric FL sensing of pH in yogurt samples, visual FL latent fingerprint and leaf imaging detection of [Cu 2+ ], dual-signal FL sensing of [Cu 2+ ] in yogurt and human serum samples. Experimental results from ratiometric, visual, dual-signal FL sensing and imaging applications confirmed the high feasibility, accuracy, stabilization and simplicity of CDs-FITC composites-based FL sensors for the detection of pH and Cu 2+ ions in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of a Nile Red-Pd-based fluorescent CO probe and its imaging applications in vitro and in vivo.

PubMed

Liu, Keyin; Kong, Xiuqi; Ma, Yanyan; Lin, Weiying

2018-05-01

Carbon monoxide (CO) is a key gaseous signaling molecule in living cells and organisms. This protocol illustrates the synthesis of a highly sensitive Nile Red (NR)-Pd-based fluorescent probe, NR-PdA, and its applications for detecting endogenous CO in tissue culture cells, ex vivo organs, and zebrafish embryos. In the NR-PdA synthesis process, 3-diethylamine phenol reacts with sodium nitrite in the acidic condition to afford 5-(diethylamino)-2-nitrosophenol hydrochloride (compound 1), which is further treated with 1-naphthalenol at a high temperature to provide the NR dye via a cyclization reaction. Finally, NR is reacted with palladium acetate to obtain the desired Pd-based fluorescent probe NR-PdA. NR-PdA possesses excellent two-photon excitation and near-IR emission properties, high stability, low background fluorescence, and a low detection limit. In addition to the chemical synthesis procedures, we provide step-by-step procedures for imaging endogenous CO in RAW 264.7 cells, mouse organs ex vivo, and live zebrafish embryos. The synthesis process for the probe requires ∼4 d, and the biological imaging experiments take ∼14 d.

Fluorescent-Magnetic-Biotargeting Multifunctional Nanobioprobes for Detecting and Isolating Multiple Types of Tumor Cells

PubMed Central

Song, Er-Qun; Hu, Jun; Wen, Cong-Ying; Tian, Zhi-Quan; Yu, Xu; Zhang, Zhi-Ling; Shi, Yun-Bo; Pang, Dai-Wen

2011-01-01

Fluorescent-magnetic-biotargeting multifunctional nanobioprobes (FMBMNs) have attracted great attention in recent years due to their increasing, important applications in biomedical research, clinical diagnosis, and biomedicine. We have previously developed such nanobioprobes for the detection and isolation of a single kind of tumor cells. Detection and isolation of multiple tumor markers or tumor cells from complex samples sensitively and with high efficiency is critical for the early diagnosis of tumors, especially malignant tumors or cancers, which will improve clinical diagnosis outcomes and help to select effective treatment approaches. Here, we expanded the application of the monoclonal antibody (mAb)-coupled FMBMNs for multiplexed assays. Multiple types of cancer cells, such as leukemia cells and prostate cancer cells, were detected and collected from mixed samples within 25 minutes by using a magnet and an ordinary fluorescence microscope. The capture efficiencies of mAb-coupled FMBMNs for the above mentioned two types of cells were 96% and 97% respectively. Furthermore, by using the mAb-coupled FMBMNs, specific and sensitive detection and rapid separation of a small number of spiked leukemia cells and prostate cancer cells in a large population of cultured normal cells (about 0.01% were tumor cells) were achieved simply and inexpensively without any sample pretreatment before cell analysis. Therefore, mAb-coupled multicolour FMBMNs may be used for very sensitive detection and rapid isolation of multiple cancer cells in biomedical research and medical diagnostics. PMID:21250650

Rapid on-site detection of airborne asbestos fibers and potentially hazardous nanomaterials using fluorescence microscopy-based biosensing.

PubMed

Kuroda, Akio; Alexandrov, Maxym; Nishimura, Tomoki; Ishida, Takenori

2016-06-01

A large number of peptides with binding affinity to various inorganic materials have been identified and used as linkers, catalysts, and building blocks in nanotechnology and nanobiotechnology. However, there have been few applications of material-binding peptides in the fluorescence microscopy-based biosensing (FM method) of environmental pollutants. A notable exception is the application of the FM method for the detection of asbestos, a dangerous industrial toxin that is still widely used in many developing countries. This review details the selection and isolation of asbestos-binding proteins and peptides with sufficient specificity to distinguish asbestos from a large variety of safer fibrous materials used as asbestos substitutes. High sensitivity to nanoscale asbestos fibers (30-35 nm in diameter) invisible under conventional phase contrast microscopy can be achieved. The FM method is the basis for developing an automated system for asbestos biosensing that can be used for on-site testing with a portable fluorescence microscope. In the future, the FM method could also become a useful tool for detecting other potentially hazardous nanomaterials in the environment. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Sensitive and Selective Sensing of Free Bilirubin Using Metal-Organic Frameworks-Based Energy Transfer Process.

PubMed

Du, Yaran; Li, Xiqian; Lv, Xueju; Jia, Qiong

2017-09-13

Free bilirubin, a key biomarker for jaundice, was detected with a newly designed fluorescent postsynthetically modified metal organic framework (MOF) (UIO-66-PSM) sensor. UiO-66-PSM was prepared based on the aldimine condensation reaction of UiO-66-NH 2 with 2,3,4-trihydroxybenzaldehyde. The fluorescence of UIO-66-PSM could be effectively quenched by free bilirubin via a fluorescent resonant energy transfer process, thus achieving its recognition of free bilirubin. It was the first attempt to design a MOF-based fluorescent probe for sensing free bilirubin. The probe exhibited fast response time, low detection limit, wide linear range, and high selectivity toward free bilirubin. The sensing system enabled the monitor of free bilirubin in real human serum. Hence, the reported free bilirubin sensing platform has potential applications for clinical diagnosis of jaundice.

A new multifunctional Schiff base as a fluorescence sensor for Al³⁺ and a colorimetric sensor for CN⁻ in aqueous media: an application to bioimaging.

PubMed

Lee, Seul Ah; You, Ga Rim; Choi, Ye Won; Jo, Hyun Yong; Kim, Ah Ram; Noh, Insup; Kim, Sung-Jin; Kim, Youngmee; Kim, Cheal

2014-05-14

A multifunctional fluorescent and colorimetric receptor 1 ((E)-N'-((8-hydroxy-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)methylene)benzohydrazide) for the detection of both Al(3+) and CN(-) in aqueous solution has been developed. Receptor 1 exhibited an excellent selective fluorescence response toward Al(3+). The sensitivity of the fluorescent based assay (0.193 μM) for Al(3+) is far below the limit in the World Health Organization (WHO) guidelines for drinking water (7.41 μM). In addition, receptor 1 showed an excellent detection ability in a wide pH range of 4-10 and also in living cells. Moreover, receptor 1 showed a highly selective colorimetric response to CN(-) by changing its color from colorless to yellow immediately without any interference from other anions.

Protoporphyrin IX fluorescence for enhanced photodynamic diagnosis and photodynamic therapy in murine models of skin and breast cancer

NASA Astrophysics Data System (ADS)

Rollakanti, Kishore Reddy

Protoporphyrin IX (PpIX) is a photosensitizing agent derived from aminolevulinic acid. PpIX accumulates specifically within target cancer cells, where it fluoresces and produces cytotoxic reactive oxygen species. Our aims were to employ PpIX fluorescence to detect squamous cell carcinoma (SCC) of the skin (Photodynamic diagnosis, PDD), and to improve treatment efficacy (Photodynamic therapy, PDT) for basal cell carcinoma (BCC) and cutaneous breast cancer. Hyperspectral imaging and a spectrometer based dosimeter system were used to detect very early SCC in UVB-irradiated murine skin, using PpIX fluorescence. Regarding PDT, we showed that low non-toxic doses of vitamin D, given before ALA application, increase tumor specific PpIX accumulation and sensitize BCC and breast cancer cells to ALA-PDT. These optical imaging methods and the combination therapy regimen (vitamin D and ALA-PDT) are promising tools for effective management of skin and breast cancer.

Enzyme-catalyzed Michael addition for the synthesis of warfarin and its determination via fluorescence quenching of L-tryptophan

NASA Astrophysics Data System (ADS)

Yuan, Yusheng; Yang, Liu; Liu, Shaopu; Yang, Jidong; Zhang, Hui; Yan, Jingjing; Hu, Xiaoli

2017-04-01

A sensitive fluorescence sensor for warfarin was proposed via quenching the fluorescence of L-tryptophan due to the interaction between warfarin and L-tryptophan. Warfarin, as one of the most effective anticoagulants, was designed and synthesized via lipase from porcine pancreas (PPL) as a biocatalyst to catalyze the Michael addition of 4-hydroxycoumarin to α, β-unsaturated enones in organic medium in the presence of water. Furthermore, the spectrofluorometry was used to detect the concentration of warfarin with a linear range and detection limit (3σ/k) of 0.04-12.0 μmol L- 1 (R2 = 0.994) and 0.01 μmol L- 1, respectively. Herein, this was the first application of bio-catalytic synthesis and fluorescence for the determination of warfarin. The proposed method was applied to determine warfarin of the drug in tablets with satisfactory results.

Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

NASA Astrophysics Data System (ADS)

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.

Red-Emitting Fluorescent Probe for Detection of γ-Glutamyltranspeptidase and Its Application of Real-Time Imaging under Oxidative Stress in Cells and in Vivo.

PubMed

Liu, Feiyan; Wang, Zhen; Wang, Wenli; Luo, Jian-Guang; Kong, Lingyi

2018-06-19

γ-Glutamyltranspeptidase (GGT) plays critical roles in regulating various physiological/pathophysiological processes including the intracellular redox homeostasis. However, an effective fluorescent probe for dissecting the relationships between GGT and oxidative stress in vivo remains largely unexplored. Herein, we present a light-up fluorescent probe (DCDHF-Glu) with long wavelength emission (613 nm) for the highly sensitive and selective detection of GGT using dicyanomethylenedihydrofuran derivative as the fluorescent reporter and γ-glutamyl group as the enzyme-active trigger. DCDHF-Glu is competent to real-time image endogenous GGT in live cells and mice. In particular, DCDHF-Glu enables the direct real-time visualization of the upregulation of GGT under drug-induced oxidative stress in the HepG2 cells and the LO2 cells, as well as in vivo, vividly implying its excellent capacity in elucidation of GGT function in GGT-related biological events.

Synthesis, optical properties and application of a set of novel pyrazole nopinone derivatives.

PubMed

Yang, Jinlai; Xu, Xu; Rui, Jian; Wang, Zhonglong; Zhang, Yan; Wang, Shifa; Wu, Liangru

2017-08-05

Pyrazole derivatives (4-6) were directly synthesized from β-pinene derivative nopinone, and they were characterized by Fourier transform infrared (FTIR) spectoscope, nuclear magnetic resonance (NMR), and mass spectrometry. Their optical properties were investigated by ultraviolet-visible spectroscopy and fluorescence spectroscopy. The three compounds emitted strong blue fluorescence in ethanol. Using a fluorescence quenching method, compound 4 could be used to detect the content (100.57%) of copper sulfate pentahydrate (≥99%) with a RSD of 1.98%, y=-0.1127×+2.7148, R 2 =0.9703 (Cu 2+ : 0.5-8.0×10 -5 mol/L), and compounds 4-6 also had utility of calculating the content of anhydrous ferric chloride at a wide range of concentration. Thus, compounds 4-6 are new functional fluorescents for detecting the content of some purchased products. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluorescence enhancement of quercetin complexes by silver nanoparticles and its analytical application

NASA Astrophysics Data System (ADS)

Liu, Ping; Zhao, Liangliang; Wu, Xia; Huang, Fei; Wang, Minqin; Liu, Xiaodan

2014-03-01

It is found that the plasmon effect of silver nanoparticles (AgNPs) helps to enhance the fluorescence intensity of the quercetin (Qu) and nucleic acids system. Qu exhibited strong fluorescence enhancement when it bound to nucleic acids in the presence of AgNPs. Based on this, a sensitive method for the determination of nucleic acids was developed. The detection limits for the nucleic acids (S/N = 3) were reduced to the ng mL-1 level. The interaction mechanism of the AgNPs-fish sperm DNA (fsDNA)-Qu system was also investigated in this paper. This complex system of Qu and AgNPs was also successfully used for the detection of nucleic acids in agarose gel electrophoresis analysis. Preliminary results indicated that AgNPs also helped to improve sensitivity in the fluorescence image analysis of Qu combined with cellular contents in Arabidopsis thaliana protoplasts.

Deciphering dynamics of clathrin-mediated endocytosis in a living organism

PubMed Central

Heidotting, Spencer P.; Huber, Scott D.

2016-01-01

Current understanding of clathrin-mediated endocytosis (CME) dynamics is based on detection and tracking of fluorescently tagged clathrin coat components within cultured cells. Because of technical limitations inherent to detection and tracking of single fluorescent particles, CME dynamics is not characterized in vivo, so the effects of mechanical cues generated during development of multicellular organisms on formation and dissolution of clathrin-coated structures (CCSs) have not been directly observed. Here, we use growth rates of fluorescence signals obtained from short CCS intensity trace fragments to assess CME dynamics. This methodology does not rely on determining the complete lifespan of individual endocytic assemblies. Therefore, it allows for real-time monitoring of spatiotemporal changes in CME dynamics and is less prone to errors associated with particle detection and tracking. We validate the applicability of this approach to in vivo systems by demonstrating the reduction of CME dynamics during dorsal closure of Drosophila melanogaster embryos. PMID:27458134

A portable fluorescence detector for fast ultra trace detection of explosive vapors

NASA Astrophysics Data System (ADS)

Xin, Yunhong; He, Gang; Wang, Qi; Fang, Yu

2011-10-01

This paper developed a portable detector based on a specific material-based fluorescent sensing film for an ultra trace detection of explosives, such as 2,4,6-trinitrotoluene (TNT) or its derivate 2,4-dinitrotoluene (DNT), in ambient air or on objects tainted by explosives. The fluorescent sensing films are based on single-layer chemistry and the signal amplification effect of conjugated polymers, which exhibited higher sensitivity and shorter response time to TNT or DNT at their vapor pressures. Due to application of the light emitting diode and the solid state photomultiplier and the cross-correlation-based circuit design technology, the device has the advantages of low-power, low-cost, small size, and an improved signal to noise ratio. The results of the experiments showed that the detector can real-time detect and identify of explosive vapors at extremely low levels; it is suitable for the identification of suspect luggage, forensic analyses, or battlefields clearing.

A highly selective long-wavelength fluorescent probe for hydrazine and its application in living cell imaging

NASA Astrophysics Data System (ADS)

Hao, Yuanqiang; Zhang, Yintang; Ruan, Kehong; Meng, Fanteng; Li, Ting; Guan, Jinsheng; Du, Lulu; Qu, Peng; Xu, Maotian

2017-09-01

A highly selective long-wavelength turn-on fluorescent probe has been developed for the detection of N2H4. The probe was prepared by conjugation the tricyanofuran-based D-π-A system with a recognizing moiety of acetyl group. In the presence of N2H4, the probe can be effectively hydrazinolysized and produce a turn-on fluorescent emission at 610 nm as well as a large red-shift in the absorption spectrum corresponding to a color change from yellow to blue. The sensing mechanism was confirmed by HPLC, MS, UV-vis, emission spectroscopic and theoretical calculation studies. The probe displayed high selectivity and sensitivity for N2H4 with a LOD (limit of detection) of 0.16 μM. Moreover, the probe was successfully utilized for the detection of hydrazine in living cells.

On the Search for Nuclear Resonance Fluorescence Signatures of 235U and 238U above 3 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warren, Glen A.; Caggiano, Joseph A.; Bertozzi, William

Nuclear resonance fluorescence is a physical process that provides an isotope-specific signature that could be used for the identification and characterization of materials. The technique involves the detection of prompt discrete-energy photons emitted from a sample that is exposed to MeV-energy photons. Potential applications of the technique range from detection of high explosives to characterization of special nuclear materials such as 235U. Pacific Northwest National Laboratory and Passport Systems have collaborated to conduct a pair of measurements to search for a nuclear resonance fluorescence response of 235U above 3 MeV and of 238U above 5 MeV using an 8 gmore » sample of highly enriched uranium and a 90 g sample of depleted uranium. No new signatures were observed. The minimum detectable integrated cross section for 235U is presented.« less

On the Search for Nuclear Resonance Fluorescence Signatures of 235U and 238U above 3 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Warren, Glen A.; Caggiano, Joseph A.; Bertozzi, William

Abstract–Nuclear resonance fluorescence is a physical process that provides an isotope-specific signature that could be used for the identification and characterization of materials. The technique involves the detection of prompt discrete-energy photons emitted from a sample that is exposed to photons in the MeV energy range. Potential applications of the technique range from detection of high explosives to characterization of special nuclear materials such as 235U. Pacific Northwest National Laboratory and Passport Systems have collaborated to conduct a a pair of measurements to search for a nuclear resonance fluorescence response of 235U above 3 MeV and of 238U above 5more » MeV using an 8 g sample of highly enriched uranium and a 90 g sample of depleted uranium. No new signatures were observed. The minimum detectable integrated cross section for 235U is presented.« less

A portable fluorescence detector for fast ultra trace detection of explosive vapors.

PubMed

Xin, Yunhong; He, Gang; Wang, Qi; Fang, Yu

2011-10-01

This paper developed a portable detector based on a specific material-based fluorescent sensing film for an ultra trace detection of explosives, such as 2,4,6-trinitrotoluene (TNT) or its derivate 2,4-dinitrotoluene (DNT), in ambient air or on objects tainted by explosives. The fluorescent sensing films are based on single-layer chemistry and the signal amplification effect of conjugated polymers, which exhibited higher sensitivity and shorter response time to TNT or DNT at their vapor pressures. Due to application of the light emitting diode and the solid state photomultiplier and the cross-correlation-based circuit design technology, the device has the advantages of low-power, low-cost, small size, and an improved signal to noise ratio. The results of the experiments showed that the detector can real-time detect and identify of explosive vapors at extremely low levels; it is suitable for the identification of suspect luggage, forensic analyses, or battlefields clearing.

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

PubMed

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.

Quantum-dot-based quantitative identification of pathogens in complex mixture

NASA Astrophysics Data System (ADS)

Lim, Sun Hee; Bestwater, Felix; Buchy, Philippe; Mardy, Sek; Yu, Alexey Dan Chin

2010-02-01

In the present study we describe sandwich design hybridization probes consisting of magnetic particles (MP) and quantum dots (QD) with target DNA, and their application in the detection of avian influenza virus (H5N1) sequences. Hybridization of 25-, 40-, and 100-mer target DNA with both probes was analyzed and quantified by flow cytometry and fluorescence microscopy on the scale of single particles. The following steps were used in the assay: (i) target selection by MP probes and (ii) target detection by QD probes. Hybridization efficiency between MP conjugated probes and target DNA hybrids was controlled by a fluorescent dye specific for nucleic acids. Fluorescence was detected by flow cytometry to distinguish differences in oligo sequences as short as 25-mer capturing in target DNA and by gel-electrophoresis in the case of QD probes. This report shows that effective manipulation and control of micro- and nanoparticles in hybridization assays is possible.

A new fluorescence turn-on nanobiosensor for the detection of micro-RNA-21 based on a DNA-gold nanocluster

NASA Astrophysics Data System (ADS)

Hosseini, Morteza; Ahmadi, Elnaz; Borghei, Yasaman-Sadat; Ganjali, Mohammad Reza

2017-03-01

In this study, DNA/gold nanoclusters (AuNCs) were used to develop an AuNC-based turn-on fluorescence probe for the analysis of mi-RNA-21, which is a potential screening biomarker for cancer detection. AuNCs on a DNA scaffold were prepared through a one-pot wet-chemical route and evaluated by transmission electron microscopy and dynamic light scattering. Experiments revealed that the fluorescence intensity of the DNA-AuNCs showed a gradual increase with the addition of the target species in a concentration range from 1pM to 10 nM. The method had a detection limit of 0.7 pM and was able to discriminate the target species from mismatched mi-RNAs very efficiently. The method was used for the determination of mi-RNA spiked human plasma samples, and was evaluated as a promising nanobiosensor for application in the selective detection of mi-RNA in various biomedical and clinical tests.

Simple and sensitive HPLC method with fluorescence detection for the measurement of ibuprofen in rat plasma: application to a long-lasting dosage form.

PubMed

Hassan, Ahmed Sheikh; Sapin, Anne; Ubrich, Nathalie; Maincent, Philippe; Bolzan, Claire; Leroy, Pierre

2008-10-01

A simple and sensitive high-performance liquid chromatography (HPLC) assay applied to the measurement of ibuprofen in rat plasma has been developed. Two parameters have been investigated to improve ibuprofen detectability using fluorescence detection: variation of mobile phase pH and the use of beta-cyclodextrin (beta-CD). Increasing the pH value from 2.5 to 6.5 and adding 5 mM beta-CD enhanced the fluorescence signal (lambda(exc) = 224 nm; lambda(em) = 290 nm) by 2.5 and 1.3-fold, respectively, when using standards. In the case of plasma samples, only pH variation significantly lowered detection and quantification limits, down to 10 and 35 ng/mL, respectively. Full selectivity was obtained with a single step for plasma treatment, that is, protein precipitation with acidified acetonitrile. The validated method was applied to a pharmacokinetic study of ibuprofen encapsulated in microspheres and subcutaneously administered to rats.

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor for the naked-eye detection of Cu2+ in ~100% aqueous media and application to real samples.

PubMed

Sun, Tao; Niu, Qingfen; Li, Tianduo; Guo, Zongrang; Liu, Haixia

2018-01-05

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor ADA for the naked-eye detection of Cu 2+ was developed. Sensor ADA showed high selectivity and sensitivity toward Cu 2+ in ~100% aqueous media over wide pH range. Sensor ADA exhibited a red-shift in the absorption spectra from 466 to 480nm that is accompanied by significant color change from light yellow to yellowish brown instantaneously. The Cu 2+ recognition is based on the chelation-enhanced fluorescence quenching (CHEQ) effect of the paramagnetic nature. The lowest detection limit is determined to be 15.8nM, which is much lower than the allowable level of Cu 2+ in drinking water set by U.S. Environmental Protection Agency (~20μM) and the World Health Organization (~30μM). The 1:1 binding process was confirmed by fluorescence measurements, IR analysis and DFT studies. Moreover, sensor ADA was successfully applied for determination of trace level of Cu 2+ with 4 reuse cycles in various water samples, which affords promising potential in ion-detection field. Copyright © 2017 Elsevier B.V. All rights reserved.

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor for the naked-eye detection of Cu2 + in 100% aqueous media and application to real samples

NASA Astrophysics Data System (ADS)

Sun, Tao; Niu, Qingfen; Li, Tianduo; Guo, Zongrang; Liu, Haixia

2018-01-01

A simple, reversible, colorimetric and water-soluble fluorescent chemosensor ADA for the naked-eye detection of Cu2 + was developed. Sensor ADA showed high selectivity and sensitivity toward Cu2 + in 100% aqueous media over wide pH range. Sensor ADA exhibited a red-shift in the absorption spectra from 466 to 480 nm that is accompanied by significant color change from light yellow to yellowish brown instantaneously. The Cu2 + recognition is based on the chelation-enhanced fluorescence quenching (CHEQ) effect of the paramagnetic nature. The lowest detection limit is determined to be 15.8 nM, which is much lower than the allowable level of Cu2 + in drinking water set by U.S. Environmental Protection Agency ( 20 μM) and the World Health Organization ( 30 μM). The 1:1 binding process was confirmed by fluorescence measurements, IR analysis and DFT studies. Moreover, sensor ADA was successfully applied for determination of trace level of Cu2 + with 4 reuse cycles in various water samples, which affords promising potential in ion-detection field.

Supramolecular nano-sniffers for ultrasensitive detection of formaldehyde.

PubMed

Akshath, Uchangi Satyaprasad; Bhatt, Praveena

2018-02-15

Supramolecular nanoparticle hybrids for biosensing of analytes have been a major focus due to their tunable optical and surface properties. Quantum dots-Gold nanoparticle (QDs-GNP) based FRET probes involving turn on/off principles have gained immense interest due to their specificity and sensitivity. Recent focus is on applying these supramolecular hybrids for enzyme operated biosensors that can specifically turn-on fluorescence induced by co-factor or product formed from enzymatic reaction. The present study focuses on locking and unlocking the interaction between QD-GNP pair leading to differential fluorescent properties. Cationic GNPs efficiently quenched the anionic QD fluorescence by forming nanoparticle hybrid. Quenching interaction between QD-GNP pair was unlocked by NADH leading to QD fluorescence turn-on. This phenomenon was applied for the successful detection of formaldehyde using NAD + dependent formaldehyde dehydrogenase. The proposed nano-sniffer could successfully detect formaldehyde from 0.001 to 100000ng/mL (R 2 = 0.9339) by the turn off-turn on principle. It could also detect formaldehyde in fruit juice and wine samples indicating its stability and sensitivity in real samples. The proposed nanoprobe can have wide applications in developing enzyme biosensors in future. Copyright © 2017 Elsevier B.V. All rights reserved.

Co-registered photoacoustic and fluorescent imaging of a switchable nanoprobe based on J-aggregates of indocyanine green

NASA Astrophysics Data System (ADS)

Dumani, Diego S.; Brecht, Hans-Peter; Ivanov, Vassili; Deschner, Ryan; Harris, Justin T.; Homan, Kimberly A.; Cook, Jason R.; Emelianov, Stanislav Y.; Ermilov, Sergey A.

2018-02-01

We introduce a preclinical imaging platform - a 3D photoacoustic/fluorescence tomography (PAFT) instrument augmented with an environmentally responsive dual-contrast biocompatible nanoprobe. The PAFT instrument was designed for simultaneous acquisition of photoacoustic and fluorescence orthogonal projections at each rotational position of a biological object, enabling direct co-registration of the two imaging modalities. The nanoprobe was based on liposomes loaded with J-aggregates of indocyanine green (PAtrace). Once PAtrace interacts with the environment, a transition from J-aggregate to monomeric ICG is induced. The subsequent recovery of monomeric ICG is characterized by dramatic changes in the optical absorption spectrum and reinstated fluorescence. In the activated state, PAtrace can be simultaneously detected by both imaging modes of the PAFT instrument using 780 nm excitation and fluorescence detection at 810 nm. The fluorescence imaging component is used to boost detection sensitivity by providing lowresolution map of activated nanoprobes, which are then more precisely mapped in 3D by the photoacoustic imaging component. Activated vs non-activated particles can be distinguished based on their different optical absorption peaks, removing the requirements for complex image registration between reference and detection scans. Preliminary phantom and in vivo animal imaging results showed successful activation and visualization of PAtrace with high sensitivity and resolution. The proposed PAFT-PAtrace imaging platform could be used in various functional and molecular imaging applications including multi-point in vivo assessment of early metastasis.

FRET-based quantum dot immunoassay for rapid and sensitive detection of Aspergillus amstelodami.

PubMed

Kattke, Michele D; Gao, Elizabeth J; Sapsford, Kim E; Stephenson, Larry D; Kumar, Ashok

2011-01-01

In this study, a fluorescence resonance energy transfer (FRET)-based quantum dot (QD) immunoassay for detection and identification of Aspergillus amstelodami was developed. Biosensors were formed by conjugating QDs to IgG antibodies and incubating with quencher-labeled analytes; QD energy was transferred to the quencher species through FRET, resulting in diminished fluorescence from the QD donor. During a detection event, quencher-labeled analytes are displaced by higher affinity target analytes, creating a detectable fluorescence signal increase from the QD donor. Conjugation and the resulting antibody:QD ratios were characterized with UV-Vis spectroscopy and QuantiT protein assay. The sensitivity of initial fluorescence experiments was compromised by inherent autofluorescence of mold spores, which produced low signal-to-noise and inconsistent readings. Therefore, excitation wavelength, QD, and quencher were adjusted to provide optimal signal-to-noise over spore background. Affinities of anti-Aspergillus antibody for different mold species were estimated with sandwich immunoassays, which identified A. fumigatus and A. amstelodami for use as quencher-labeled- and target-analytes, respectively. The optimized displacement immunoassay detected A. amstelodami concentrations as low as 10(3) spores/mL in five minutes or less. Additionally, baseline fluorescence was produced in the presence of 10(5) CFU/mL heat-killed E. coli O157:H7, demonstrating high specificity. This sensing modality may be useful for identification and detection of other biological threat agents, pending identification of suitable antibodies. Overall, these FRET-based QD-antibody biosensors represent a significant advancement in detection capabilities, offering sensitive and reliable detection of targets with applications in areas from biological terrorism defense to clinical analysis.

FRET-Based Quantum Dot Immunoassay for Rapid and Sensitive Detection of Aspergillus amstelodami

PubMed Central

Kattke, Michele D.; Gao, Elizabeth J.; Sapsford, Kim E.; Stephenson, Larry D.; Kumar, Ashok

2011-01-01

In this study, a fluorescence resonance energy transfer (FRET)-based quantum dot (QD) immunoassay for detection and identification of Aspergillus amstelodami was developed. Biosensors were formed by conjugating QDs to IgG antibodies and incubating with quencher-labeled analytes; QD energy was transferred to the quencher species through FRET, resulting in diminished fluorescence from the QD donor. During a detection event, quencher-labeled analytes are displaced by higher affinity target analytes, creating a detectable fluorescence signal increase from the QD donor. Conjugation and the resulting antibody:QD ratios were characterized with UV-Vis spectroscopy and QuantiT protein assay. The sensitivity of initial fluorescence experiments was compromised by inherent autofluorescence of mold spores, which produced low signal-to-noise and inconsistent readings. Therefore, excitation wavelength, QD, and quencher were adjusted to provide optimal signal-to-noise over spore background. Affinities of anti-Aspergillus antibody for different mold species were estimated with sandwich immunoassays, which identified A. fumigatus and A. amstelodami for use as quencher-labeled- and target-analytes, respectively. The optimized displacement immunoassay detected A. amstelodami concentrations as low as 103 spores/mL in five minutes or less. Additionally, baseline fluorescence was produced in the presence of 105 CFU/mL heat-killed E. coli O157:H7, demonstrating high specificity. This sensing modality may be useful for identification and detection of other biological threat agents, pending identification of suitable antibodies. Overall, these FRET-based QD-antibody biosensors represent a significant advancement in detection capabilities, offering sensitive and reliable detection of targets with applications in areas from biological terrorism defense to clinical analysis. PMID:22163961

Protoporphyrin IX distribution after intra-articular and systemic application of 5-aminolevulinic acid in healthy and arthritic joints

NASA Astrophysics Data System (ADS)

Huettmann, Gereon; Hendrich, Christian; Birngruber, Reginald; Lehnert, Christiane; Seara, Jose; Siebert, Werner E.; Diddens, Heyke C.

1996-04-01

Arthroscopic synovectomy, which is limited today to the large joints, is an important early treatment of rheumatoid arthritis (RA). Photodynamic therapy (PDT) is potentially to be a less invasive method of removing the synovial membrane. Therefore, in a rabbit model of RA, the accumulation of the photosensitizer Protoporphyrin IX (PPIX) after intra-articular and systemic application of ALA into arthritic rabbit knee joints was studied in skin, patella, synovial tissue, and meniscus by fluorescence microscopy. PPIX fluorescence was measured in biopsies taken at different times after application of neutral and acid ALA solutions. Significant PPIX fluorescence was observed in the synovial membrane and skin 2 and 4 hours after application. Using intra-articular application, ALA solutions prepared with pH 5.5 were at least as efficient as neutral solutions in sensitizing the synovial membrane. Skin also showed PPIX within 4 hours after application. After 24 hours, a marginal PPIX fluorescence was detected in these tissues. On the other hand, in cartilage and meniscus significant PPIX accumulation was still observed 24 hours after ALA injection. Systemic application of ALA also showed a good accumulation of PPIX. Further experiments are needed to show whether accumulation of the photosensitizer and tissue selectivity are sufficient for a successful treatment of rheumatoid synovitis.

Nanogap embedded silver gratings for surface plasmon enhanced fluorescence

NASA Astrophysics Data System (ADS)

Bhatnagar, Kunal

Plasmonic nanostructures have been extensively used in the past few decades for applications in sub-wavelength optics, data storage, optoelectronic circuits, microscopy and bio-photonics. The enhanced electromagnetic field produced at the metal and dielectric interface by the excitation of surface plasmons via incident radiation can be used for signal enhancement in fluorescence and surface enhanced Raman scattering studies. Novel plasmonic structures have shown to provide very efficient and extreme light concentration at the nano-scale in recent years. The enhanced electric field produced within a few hundred nanometers of these surfaces can be used to excite fluorophores in the surrounding environment. Fluorescence based bio-detection and bio-imaging are two of the most important tools in the life sciences and improving the qualities and capabilities of fluorescence based detectors and imaging equipment remains a big challenge for industry manufacturers. We report a novel fabrication technique for producing nano-gap embedded periodic grating substrates on the nanoscale using a store bought HD-DVD and conventional soft lithography procedures. Polymethylsilsesquioxane (PMSSQ) polymer is used as the ink for the micro-contact printing process with PDMS stamps obtained from the inexpensive HD-DVDs as master molds. Fluorescence enhancement factors of up to 118 times were observed with these silver nanostructures in conjugation with Rhodamine-590 fluorescent dye. These substrates are ideal candidates for a robust and inexpensive optical system with applications such as low-level fluorescence based analyte detection, single molecule imaging, and surface enhanced Raman studies. Preliminary results in single molecule experiments have also been obtained by imaging individual 3 nm and 20 nm dye-doped nanoparticles attached to the silver plasmonic gratings using epi-fluorescence microscopy.

Linear Schiff-base fluorescence probe with aggregation-induced emission characteristics for Al3+ detection and its application in live cell imaging.

PubMed

Wen, Xiaoye; Fan, Zhefeng

2016-11-16

A simple Schiff-base derivative with salicylaldehyde moieties as fluorescent probe 1 was reported by aggregation-induced emission (AIE) characterization for the detection of metal ions. Spectral analysis revealed that probe 1 was highly selective and sensitive to Al 3+ . The probe 1 was also subject to minimal interference from other common competitive metal ions. The detection limit of Al 3+ was 0.4 μM, which is considerably lower than the World Health Organization standard (7.41 μM), and the acceptable level of Al 3+ (1.85 μM) in drinking water. The Job's plot and the results of 1 H-NMR and FT-IR analyses indicated that the binding stoichiometry ratio of probe 1 to Al 3+ was 1:2. Probe 1 demonstrated a fluorescence-enhanced response upon binding with Al 3+ based on AIE characterization. This response was due to the restricted molecular rotation and increased rigidity of the molecular assembly. Probe 1 exhibited good biocompatibility, and Al 3+ was detected in live cells. Therefore, probe 1 is a promising fluorescence probe for Al 3+ detection in the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of micellar structure and drag reduction in a surfactant solution flow using the fluorescence probe method

NASA Astrophysics Data System (ADS)

Wakimoto, Tatsuro; Araga, Koichi; Katoh, Kenji

2018-03-01

As widely known, the addition of a specific type of surfactant to water reduces drag in a pipe flow. This effect is considered to be a result of the suppression of turbulent transition caused by the ordered structure of rod-like micelles that is referred to as a shear-induced structure (SIS). However, it is typically difficult to determine the SIS since it is necessary to noninvasively detect the SIS with several hundred nanometers in the actual moving flow. In this study, we used the fluorescence probe method to locally determine the SIS in a pipe flow. When hydrophobic fluorescence molecules are added to the surfactant solution, the fluorescence molecules are trapped in micelles. Thus, fluorescence intensity varies based on the change in the micellar structure. We verified the applicability of the fluorescence probe method to the SIS detection and determined the relationship between the micellar structure and the drag reduction in the pipe flow by simultaneously measuring the fluorescence intensity and pipe friction factor. The experimental result demonstrates that the SIS formation in the near-wall region is closely correlated with the drag reduction and suggests that the near-wall SIS suppresses the turbulent transition.

A compact multi-channel fluorescence sensor with ambient light suppression

NASA Astrophysics Data System (ADS)

Egly, Dominik; Geörg, Daniel; Rädle, Matthias; Beuermann, Thomas

2012-03-01

A multi-channel fluorescence sensor has been developed for process monitoring and fluorescence diagnostics. It comprises a fiber-optic set-up with an immersion probe and an intensity-modulated high power ultraviolet light-emitting diode as a light source for fluorescence excitation. By applying an electronic lock-in procedure, fluorescence signals are selectively detectable at ambient light levels of 1000 000 times higher intensity. The sensor was designed to be compact, low cost and easily adaptable to a wide field of application. The set-up was used to simultaneously monitor three important metabolic fluorophores: NAD(P)H, flavins and porphyrins during the cultivation of a baker's yeast. Moreover, the accumulation and degradation kinetics of protoporphyrin IX induced by 5-aminolevulinic acid on the skin could be recorded by the sensor. The detection limit for protoporphyrin IX was determined to be 4 × 10-11 mol L-1. The linear signal amplification of the sensor and time courses of fluorescence signals monitored during yeast fermentations were validated using a commercial CCD spectrometer. The robust and flexible set-up of the fiber-optic measurement system promises easy implementation of this non-invasive analytical tool to fluorescence monitoring and diagnostics in R&D and production.

Nano-Gap Embedded Plasmonic Gratings for Surface Plasmon Enhanced Fluorescence

NASA Astrophysics Data System (ADS)

Bhatnagar, Kunal; Bok, Sangho; Korampally, Venumadhav; Gangopadhyay, Shubhra

2012-02-01

Plasmonic nanostructures have been extensively used in the past few decades for applications in sub-wavelength optics, data storage, optoelectronic circuits, microscopy and bio-photonics. The enhanced electromagnetic field produced at the metal/dielectric interface by the excitation of surface plasmons via incident radiation can be used for signal enhancement in fluorescence and surface enhanced Raman scattering studies. Novel plasmonic structures on the sub wavelength scale have been shown to provide very efficient and extreme light concentration at the nano-scale. The enhanced electric field produced within a few hundred nanometers of these structures can be used to excite fluorophores in the surrounding environment. Fluorescence based bio-detection and bio-imaging are two of the most important tools in the life sciences. Improving the qualities and capabilities of fluorescence based detectors and imaging equipment has been a big challenge to the industry manufacturers. We report the novel fabrication of nano-gap embedded periodic grating substrates on the nanoscale using micro-contact printing and polymethylsilsesquioxane (PMSSQ) polymer. Fluorescence enhancement of up to 118 times was observed with these silver nanostructures in conjugation with Rhodamine-590 fluorescent dye. These substrates are ideal candidates for low-level fluorescence detection and single molecule imaging.

Versatile microfluidic total internal reflection (TIR)-based devices: application to microbeads velocity measurement and single molecule detection with upright and inverted microscope.

PubMed

Le, Nam Cao Hoai; Yokokawa, Ryuji; Dao, Dzung Viet; Nguyen, Thien Duy; Wells, John C; Sugiyama, Susumu

2009-01-21

A poly(dimethylsiloxane) (PDMS) chip for Total Internal Reflection (TIR)-based imaging and detection has been developed using Si bulk micromachining and PDMS casting. In this paper, we report the applications of the chip on both inverted and upright fluorescent microscopes and confirm that two types of sample delivery platforms, PDMS microchannel and glass microchannel, can be easily integrated depending on the magnification of an objective lens needed to visualize a sample. Although any device configuration can be achievable, here we performed two experiments to demonstrate the versatility of the microfluidic TIR-based devices. The first experiment was velocity measurement of Nile red microbeads with nominal diameter of 500 nm in a pressure-driven flow. The time-sequenced fluorescent images of microbeads, illuminated by an evanescent field, were cross-correlated by a Particle Image Velocimetry (PIV) program to obtain near-wall velocity field of the microbeads at various flow rates from 500 nl/min to 3000 nl/min. We then evaluated the capabilities of the device for Single Molecule Detection (SMD) of fluorescently labeled DNA molecules from 30 bp to 48.5 kbp and confirm that DNA molecules as short as 1105 bp were detectable. Our versatile, integrated device could provide low-cost and fast accessibility to Total Internal Reflection Fluorescent Microscopy (TIRFM) on both conventional upright and inverted microscopes. It could also be a useful component in a Micro-Total Analysis System (micro-TAS) to analyze nanoparticles or biomolecules near-wall transport or motion.

Fabrication of valine-functionalized graphene quantum dots and its use as a novel optical probe for sensitive and selective detection of Hg2 +

NASA Astrophysics Data System (ADS)

Xiaoyan, Zhou; Zhangyi, Li; Zaijun, Li

2017-01-01

The functionalization of graphene quantum dots has become a powerful method to modulate its chemical, electronic and optical properties for various applications. In the study, we reported a facile synthesis of valine-functionalized graphene quantum dots (Val-GQDs) and its use as a novel fluorescent probe for optical detection of Hg2 +. Herein, Val-GQDs was synthesized by the thermal pyrolysis of citric acid and valine. The resulting Val-GQDs has an average size of 3 nm and the edge of graphene sheets contains the rich of hydrophilic groups, leading to a high water-solubility. Compared to the GQDs prepared by thermal pyrolysis of citric acid, Val-GQDs exhibits a stronger fluorescence (> 10-fold) and better photostability (> 4-fold). Interestingly, the existence of valine moieties in the Val-GQDs results in a more sensitive fluorescent response to Hg2 +. The fluorescent signal will linearly decrease with the increase of Hg2 + concentration in the range from 0.8 nM to 1 μM with the correlation coefficient of 0.992. The detection limit is 0.4 nM (S/N = 3), which the sensitivity is > 14-fold that of GQDs. The analytical method provides the prominent advantage of sensitivity, selectivity and stability. It has been successfully applied in the optical detection of Hg2 + in real water samples. The study also provides a promising approach for the design and synthesis of functionalized GQDs to meet the needs of further applications in sensing and catalysis.

On the viability of exploiting L-shell fluorescence for X-ray polarimetry

NASA Technical Reports Server (NTRS)

Weisskopf, M. C.; Sutherland, P. G.; Elsner, R. F.; Ramsey, B. D.

1985-01-01

It has been suggested that one may build an X-ray polarimeter by exploiting the polarization dependence of the angular distribution of L-shell fluorescence photons. In this paper the sensitivity of this approach to polarimetry is examined theoretically. The calculations are applied to several detection schemes using imaging proportional counters that would have direct application in X-ray astronomy. It is found, however, that the sensitivity of this method for measuring X-ray polarization is too low to be of use for other than laboratory applications.

Laser induced fluorescence technique for environmental applications

NASA Astrophysics Data System (ADS)

Utkin, Andrei B.; Felizardo, Rui; Gameiro, Carla; Matos, Ana R.; Cartaxana, Paulo

2014-08-01

We discuss the development of laser induced fluorescence sensors and their application in the evaluation of water pollution and physiological status of higher plants and algae. The sensors were built on the basis of reliable and robust solid-state Nd:YAG lasers. They demonstrated good efficiency in: i) detecting and characterizing oil spills and dissolved organic matter; ii) evaluating the impact of stress on higher plants (cork oak, maritime pine, and genetically modified Arabidopsis); iii) tracking biomass changes in intertidal microphytobenthos; and iv) mapping macroalgal communities in the Tagus Estuary.

Remote Detection of Biological Particles and Chemical Plumes Using UV Fluorescence Lidar

NASA Technical Reports Server (NTRS)

Tiee, J. J.; Hof, D. E.; Karl, R. R.; Martinez, R. J.; Quick, C. R.; Cooper, D. I.; Eichinger, W. E.; Holtkamp, D. B.

1992-01-01

A lidar system based on ultraviolet (UV) laser induced fluorescence (LIF) was developed for the remote detection of atmospherically dispersed biological particles and chemical vapors. This UV fluorescence lidar has many potential applications for monitoring environmental pollution, industrial waste emission, agricultural insect control, illicit chemical processing, and military defense operations. The general goal of this work is to investigate the research issues associated with the long range detection and identification of chemicals, e.g. aromatic solvents and chemical precursors, and biological materials, e.g. bacillus thuringiensis (BT) and bacillus globiggi (BG). In the detection of biological particulates, we are particularly interested in extending the detection range of an existing solar-blind 248-nm lidar system. We are investigating the use of longer excitation laser wavelengths (i.e. lambda greater than 280-nm to have more favorable atmospheric light transmission characteristics) for improving detection range to better than 10 km. In the detection of chemical plumes, our main research objectives are to determine how accurately and sensitively a chemical plume can be located at range, and how well spectrally the chemical species can be measured to allow their identification.

Study on excitation and fluorescence spectrums of Japanese citruses to construct machine vision systems for acquiring fluorescent images

NASA Astrophysics Data System (ADS)

Momin, Md. Abdul; Kondo, Naoshi; Kuramoto, Makoto; Ogawa, Yuichi; Shigi, Tomoo

2011-06-01

Research was conducted to acquire knowledge of the ultraviolet and visible spectrums from 300 -800 nm of some common varieties of Japanese citrus, to investigate the best wave-lengths for fluorescence excitation and the resulting fluorescence wave-lengths and to provide a scientific background for the best quality fluorescent imaging technique for detecting surface defects of citrus. A Hitachi U-4000 PC-based microprocessor controlled spectrophotometer was used to measure the absorption spectrum and a Hitachi F-4500 spectrophotometer was used for the fluorescence and excitation spectrums. We analyzed the spectrums and the selected varieties of citrus were categorized into four groups of known fluorescence level, namely strong, medium, weak and no fluorescence.The level of fluorescence of each variety was also examined by using machine vision system. We found that around 340-380 nm LEDs or UV lamps are appropriate as lighting devices for acquiring the best quality fluorescent image of the citrus varieties to examine their fluorescence intensity. Therefore an image acquisition device was constructed with three different lighting panels with UV LED at peak 365 nm, Blacklight blue lamps (BLB) peak at 350 nm and UV-B lamps at peak 306 nm. The results from fluorescent images also revealed that the findings of the measured spectrums worked properly and can be used for practical applications such as for detecting rotten, injured or damaged parts of a wide variety of citrus.

Boronic acid recognition of non-interacting carbohydrates for biomedical applications: increasing fluorescence signals of minimally interacting aldoses and sucralose.

PubMed

Resendez, Angel; Halim, Md Abdul; Singh, Jasmeet; Webb, Dominic-Luc; Singaram, Bakthan

2017-11-22

To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen-HPTS (4,4'-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH 4 ) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields. Compared to original aldoses, apparent binding affinities were increased 4-25-fold. The chlorinated sweetener and colon permeability marker sucralose (Splenda), otherwise undetectable by boronic acids, was dechlorinated to a detectable derivative by reactive oxygen and hydroxide intermediates by the Fenton reaction or by H 2 O 2 and UV light. This method is specific to sucralose as other common sugars, such as sucrose, do not contain any carbon-chlorine bonds. Significant fluorescence response was obtained for chemically modified sucralose with the 4,4'-o-BBV-HPTS probe system. This proof of principle can be applied to biomedical applications, such as gut permeability, malabsorption, etc.

A robust and versatile signal-on fluorescence sensing strategy based on SYBR Green I dye and graphene oxide

PubMed Central

Qiu, Huazhang; Wu, Namei; Zheng, Yanjie; Chen, Min; Weng, Shaohuang; Chen, Yuanzhong; Lin, Xinhua

2015-01-01

A robust and versatile signal-on fluorescence sensing strategy was developed to provide label-free detection of various target analytes. The strategy used SYBR Green I dye and graphene oxide as signal reporter and signal-to-background ratio enhancer, respectively. Multidrug resistance protein 1 (MDR1) gene and mercury ion (Hg2+) were selected as target analytes to investigate the generality of the method. The linear relationship and specificity of the detections showed that the sensitive and selective analyses of target analytes could be achieved by the proposed strategy with low detection limits of 0.5 and 2.2 nM for MDR1 gene and Hg2+, respectively. Moreover, the strategy was used to detect real samples. Analytical results of MDR1 gene in the serum indicated that the developed method is a promising alternative approach for real applications in complex systems. Furthermore, the recovery of the proposed method for Hg2+ detection was acceptable. Thus, the developed label-free signal-on fluorescence sensing strategy exhibited excellent universality, sensitivity, and handling convenience. PMID:25565810

Mobile flow cytometer for mHealth.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2015-01-01

Flow cytometry is used for cell counting and analysis in numerous clinical and environmental applications. However flow cytometry is not used in mHealth mainly because current flow cytometers are large, expensive, power-intensive devices designed to operate in a laboratory. Their design results in a lack of portability and makes them unsuitable for mHealth applications. Another limitation of current technology is the low volumetric throughput rates that are not suitable for rapid detection of rare cells.To address these limitations, we describe here a novel, low-cost, mobile flow cytometer based on wide-field imaging with a webcam for large volume and high throughput fluorescence detection of rare cells as a simulation for circulating tumor cells (CTCs) detection. The mobile flow cytometer uses a commercially available webcam capable of 187 frames per second video capture at a resolution of 320 × 240 pixels. For fluorescence detection, a 1 W 450 nm blue laser is used for excitation of Syto-9 fluorescently stained cells detected at 535 nm. A wide-field flow cell was developed for large volume analysis that allows for the linear velocity of target cells to be lower than in conventional hydrodynamic focusing flow cells typically used in cytometry. The mobile flow cytometer was found to be capable of detecting low concentrations at flow rates of 500 μL/min, suitable for rare cell detection in large volumes. The simplicity and low cost of this device suggests that it may have a potential clinical use for mHealth flow cytometry for resource-poor settings associated with global health.

Detection of a variable number of ribosomal DNA loci by fluorescent in situ hybridization in Populus species.

PubMed

Prado, E A; Faivre-Rampant, P; Schneider, C; Darmency, M A

1996-10-01

Fluorescent in situ hybridization (FISH) was applied to related Populus species (2n = 19) in order to detect rDNA loci. An interspecific variability in the number of hybridization sites was revealed using as probe an homologous 25S clone from Populus deltoides. The application of image analysis methods to measure fluorescence intensity of the hybridization signals has enabled us to characterize major and minor loci in the 18S-5.8S-25S rDNA. We identified one pair of such rDNA clusters in Populus alba; two pairs, one major and one minor, in both Populus nigra and P. deltoides; and three pairs in Populus balsamifera, (two major and one minor) and Populus euroamericana (one major and two minor). FISH results are in agreement with those based on RFLP analysis. The pBG13 probe containing 5S sequence from flax detected two separate clusters corresponding to the two size classes of units that coexist within 5S rDNA of most Populus species. Key words : Populus spp., fluorescent in situ hybridization, FISH, rDNA variability, image analysis.

A fluorescence glucose sensor based on pH induced conformational switch of i-motif DNA.

PubMed

Ke, Qingqing; Zheng, Yu; Yang, Fan; Zhang, Hanchang; Yang, Xiurong

2014-11-01

A facile fluorescence biosensor for the detection of glucose is proposed based on the pH-induced conformational switch of i-motif DNA in this paper. Glucose can be oxidized by oxygen (O2) in the presence of glucose oxidase (GOD), and the generated gluconic acid can decrease the pH value of the solution and then induce the fluorophore- and quencher-labeled cytosine-rich single-stranded DNA to fold into a close-packed i-motif structure. As a result, the fluorescence quenching occurs because of the resonance energy transfer between fluorophore and quencher. Based on this working principle, the concentration of glucose can be detected by the decrease of fluorescence density. Under the optimal experimental conditions, the assay shows a linear response range of 5-100 µM for the glucose concentration with a detection limit of 4 µM. This glucose biosensor was applied to determine glucose in real samples successfully, suggesting its potential in the practical applicability. Copyright © 2014 Elsevier B.V. All rights reserved.

Lanthanide-doped upconverting phosphors for bioassay and therapy

NASA Astrophysics Data System (ADS)

Guo, Huichen; Sun, Shiqi

2012-10-01

Lanthanide-doped fluorescent materials have gained increasing attention in recent years due to their unique luminescence properties which have led to their use in wide-ranging fields including those of biological applications. Aside from being used as agents for in vivo imaging, lanthanide-doped fluorescent materials also present many advantages for use in bioassays and therapy. In this review, we summarize the applications of lanthanide-doped up-converting phosphors (UCPs) in protein and gene detection, as well as in photodynamic and gene therapy in recent years, and outline their future potential in biological applications. The current report could serve as a reference for researchers in relevant fields.

Fluorimetric detection of Sn(2+) ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis.

PubMed

Patil, Kishor S; Mahajan, Prasad G; Patil, Shivajirao R

2017-01-05

The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn(2+) ions by enhancing the fluorescence intensity preference to Cu(2+), Fe(3+), Fe(2+), Ni(2+), NH4(+), Ca(2+), Pb(2+), Hg(2+) and Zn(2+) ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV-visible and fluorescence titration with and without Sn(2+) helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn(2+) and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn(2+) is further used to develop an analytical method for detection of Sn(2+) from aqueous medium in environmental samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorimetric detection of Sn2 + ion in aqueous medium using Salicylaldehyde based nanoparticles and application to natural samples analysis

NASA Astrophysics Data System (ADS)

Patil, Kishor S.; Mahajan, Prasad G.; Patil, Shivajirao R.

2017-01-01

The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3 nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn2 + ions by enhancing the fluorescence intensity preference to Cu2 +, Fe3 +, Fe2 +, Ni2 +, NH4+, Ca2 +, Pb2 +, Hg2 + and Zn2 + ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV-visible and fluorescence titration with and without Sn2 + helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn2 + and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn2 + is further used to develop an analytical method for detection of Sn2 + from aqueous medium in environmental samples.

Fluorescence detection of oral squamous cell carcinoma using Hyperflav

NASA Astrophysics Data System (ADS)

Melnik, Ivan S.; Dets, Sergiy M.; Rawicz, Andrew H.; Zhang, Lewei

2000-05-01

A novel hypericin-based drug HyperflavTM has been evaluated for light-induced fluorescence detection of oral cancer. Squamous cell carcinoma was induced with carcinogenic agent in right pouches of forty hamsters (20/20 males/females). Solution of HyperflavTM was sprinkled into stomach with a single dose 0.2 - 4 mg of pure hypericin per kg b.w. and 4 - 8 hours before fluorescence analysis. In two animal groups with cancer symptoms the autofluorescence and hypericin-induced fluorescence were taken under 442 nm excitation. The buccal mucosa and adjacent areas were measured fiberoptically in-vivo and in-vitro using orange/green ratio (610/540). The in-vivo fluorescence imaging of malignant areas was conducted to assist the biopsy guidance and to compare with white-light images. Histological and morphological analyses were performed from biopsies. Oral squamous cell carcinoma in its early stage demonstrated specific higher 610/540 ratio for 37 tested hamsters. Advanced state involved another higher fluorescence maximum around 640 nm that in our opinion caused by strong porphyrin-induced native fluorescence. Such deformation of fluorescence spectra may lead to inadequate perception of diseased tissue area. To avoid this problem the autofluorescence spectra & images were added. HyperflavTM application is promising for demarcation of early oral cancer when combined with autofluorescence measurements.

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

PubMed

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.

Analytical cytology applied to detection of prognostically important cytogenetic aberrations: Current status and future directions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, J.W.; Pinkel, D.; Trask, B.

1987-07-24

This paper discusses the application of analytical cytology to the detection of clinically important chromosome abnormalities in human tumors. Flow cytometric measurements of DNA distributions have revealed that many human tumors have abnormal (usually elevated) DNA contents and that the occurrence of DNA abnormality may be diagnostically or prognostically important. However, DNA indices (ratio of tumor DNA content to normal DNA content) provide little information about the specific chromosome(s) involved in the DNA content abnormality. Fluorescence in situ hybridization with chromosome specific probes is suggested as a technique to facilitate detection of specific chromosome aneuploidy in interphase and metaphase humanmore » tumor cells. Fluorescence hybridization to nuclei on slides allows enumeration of brightly fluorescent nuclear domains as an estimate of the number of copies of the chromosome type for which the hybridization probe is specific. Fluorescence hybridization can also be made to nuclei in suspension. The fluorescence intensity can then be measured flow cytometrically as an indication of the number of chromosomes in each nucleus carrying the DNA sequence homologous to the probe. In addition, quantitative image analysis may be used to explore the position of chromosomes in interphase nuclei and to look for changes in the order that may eventually permit detection of clinicaly important conditions. 55 refs., 8 figs., 1 tab.« less

Carbon dots as fluorescent probes for "off-on" detection of Cu2+ and L-cysteine in aqueous solution.

PubMed

Zong, Jie; Yang, Xiaoling; Trinchi, Adrian; Hardin, Simon; Cole, Ivan; Zhu, Yihua; Li, Chunzhong; Muster, Tim; Wei, Gang

2014-01-15

Copper ion (Cu(2+)) and L-cysteine (L-Cys) detection is critically important since an abnormal level of Cu(2+) or L-Cys is an indicator for many diseases. In this paper, we demonstrate an "off-on" approach for highly sensitive and selective detection of Cu(2+) and L-Cys using carbon dots (CDs) as fluorescent probes. CDs were prepared by using mesoporous silica (MS) spheres as nanoreactors. The binding ability of CDs towards metal ions was examined by comparing the fluorescence intensities of CDs before and after the addition of the metal ions. The addition of Cu(2+) cations leads to their absorption on the surface of CDs and the significant fluorescence quench of CDs (turn-off). The resulting in CDs-Cu(2+) system was found to be sensitive to L-Cys. The addition of L-Cys not only serves to shelter the CDs effectively from being quenched, but also to reverse the quenching and restore the fluorescence (turn-on) due to its ability to remove Cu(2+) from the surface of CDs. This method is facile, rapid, low cost, and environment-friendly. A detection limit as low as 2.3×10(-8) M for Cu(2+) and 3.4×10(-10) M for L-Cys is obtained, which is promising for biological applications. © 2013 Elsevier B.V. All rights reserved.

Coherent nonlinear optical imaging: beyond fluorescence microscopy.

PubMed

Min, Wei; Freudiger, Christian W; Lu, Sijia; Xie, X Sunney

2011-01-01

The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy (including stimulated Raman scattering and two-photon absorption) and pump-probe microscopy (including excited-state absorption, stimulated emission, and ground-state depletion), provides new image contrasts for nonfluorescent species. Thanks to the high-frequency modulation transfer scheme, these imaging techniques exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles and excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques.

A dual-function fluorescent probe for monitoring the degrees of hypoxia in living cells via the imaging of nitroreductase and adenosine triphosphate.

PubMed

Fang, Yu; Shi, Wen; Hu, Yiming; Li, Xiaohua; Ma, Huimin

2018-05-24

A new dual-function fluorescent probe is developed for detecting nitroreductase (NTR) and adenosine triphosphate (ATP) with different responses. Imaging application of the probe reveals that intracellular NTR and ATP display an adverse changing trend during a hypoxic process and ATP can serve as a new sign for cell hypoxia.

Nanoroughened plasmonic films for enhanced biosensing detection

NASA Astrophysics Data System (ADS)

LeMoal, Eric; Lévêque-Fort, Sandrine; Potier, Marie-Claude; Fort, Emmanuel

2009-06-01

Although fluorescence is the prevailing labeling technique in biosensing applications, sensitivity improvement is still a striving challenge. We show that coating standard microscope slides with nanoroughened silver films provides a high fluorescence signal enhancement due to plasmonic interactions. As a proof of concept, we applied these films with tailored plasmonic properties to DNA microarrays. Using common optical scanning devices, we achieved signal amplifications of more than 40-fold.

A selective colorimetric and fluorescent sensor for Al3+ ion and its application to cellular imaging

NASA Astrophysics Data System (ADS)

Manjunath, Rangasamy; Hrishikesan, Elango; Kannan, Palaninathan

2015-04-01

A new rhodamine-based fluorescent turn-on chemosensor (L) for selective detection of Al3+ ion has been developed and characterized. The fluorescent chemosensor L was synthesized by the reaction of intermediate (4) with 2,5-bis (4-phenylacyl chloride)-1,3,4-oxadiazole (3). The chemosensor L displays an excellent selective and sensitive response to Al3+ ion over other metal ions, in which the spirocyclic (non-fluorescent) to ring opened amide (fluorescent) process was utilized and a 1:2 stoichiometry for L-Al3+ complex was formed with an association constant of 2.03 × 103 M-1. Furthermore, chemosensor L can be applied as a fluorescent probe for monitoring Al3+ in living cells by performing cell imaging studies.

Recent advances in biocompatible semiconductor nanocrystals for immunobiological applications.

PubMed

Nanda, Sitansu Sekhar; Kim, Min Jik; Kim, Kwangmeyung; Papaefthymiou, Georgia C; Selvan, Subramanian Tamil; Yi, Dong Kee

2017-11-01

Quantum confinement in inorganic semiconductor nanocrystals produces brightly luminescent nanoparticles endowed with unique photo-physical properties, such as tunable optical properties. These have found widespread applications in nanotechnology. The ability to render such nanostructures biocompatible, while maintaining their tunable radiation in the visible range of the electromagnetic spectrum, renders them appropriate for bio-applications. Promising in vitro and in vivo diagnostic applications have been demonstrated, such as fluorescence-based detection of biological interactions, single molecule tracking, multiplexing and immunoassaying. In particular, these fluorescent inorganic semiconductor nanocrystals, generally known as quantum dots, have the potential of remarkable immunobiological applications. This review focuses on the current status of biocompatible quantum dots and their applications in immunobiology - immunosensing, immunofluorescent imaging and immunotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluorescence correlation spectroscopy: novel variations of an established technique.

PubMed

Haustein, Elke; Schwille, Petra

2007-01-01

Fluorescence correlation spectroscopy (FCS) is one of the major biophysical techniques used for unraveling molecular interactions in vitro and in vivo. It allows minimally invasive study of dynamic processes in biological specimens with extremely high temporal and spatial resolution. By recording and correlating the fluorescence fluctuations of single labeled molecules through the exciting laser beam, FCS gives information on molecular mobility and photophysical and photochemical reactions. By using dual-color fluorescence cross-correlation, highly specific binding studies can be performed. These have been extended to four reaction partners accessible by multicolor applications. Alternative detection schemes shift accessible time frames to slower processes (e.g., scanning FCS) or higher concentrations (e.g., TIR-FCS). Despite its long tradition, FCS is by no means dated. Rather, it has proven to be a highly versatile technique that can easily be adapted to solve specific biological questions, and it continues to find exciting applications in biology and medicine.

Comparison of three PCR-based assays for SNP genotyping in sugar beet

USDA-ARS?s Scientific Manuscript database

Background: PCR allelic discrimination technologies have broad applications in the detection of single nucleotide polymorphisms (SNPs) in genetics and genomics. The use of fluorescence-tagged probes is the leading method for targeted SNP detection, but assay costs and error rates could be improved t...

Pancreatic tissue assessment using fluorescence and reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Chandra, Malavika; Heidt, David; Simeone, Diane; McKenna, Barbara; Scheiman, James; Mycek, Mary-Ann

2007-07-01

The ability of multi-modal optical spectroscopy to detect signals from pancreatic tissue was demonstrated by studying human pancreatic cancer xenografts in mice and freshly excised human pancreatic tumor tissue. Measured optical spectra and fluorescence decays were correlated with tissue morphological and biochemical properties. The measured spectral features and decay times correlated well with expected pathological differences in normal, pancreatitis and adenocarcinoma tissue states. The observed differences between the fluorescence and reflectance properties of normal, pancreatitis and adenocarcinoma tissue indicate a possible application of multi-modal optical spectroscopy to differentiating between the three tissue classifications.

Robust Smoothing: Smoothing Parameter Selection and Applications to Fluorescence Spectroscopy∂

PubMed Central

Lee, Jong Soo; Cox, Dennis D.

2009-01-01

Fluorescence spectroscopy has emerged in recent years as an effective way to detect cervical cancer. Investigation of the data preprocessing stage uncovered a need for a robust smoothing to extract the signal from the noise. Various robust smoothing methods for estimating fluorescence emission spectra are compared and data driven methods for the selection of smoothing parameter are suggested. The methods currently implemented in R for smoothing parameter selection proved to be unsatisfactory, and a computationally efficient procedure that approximates robust leave-one-out cross validation is presented. PMID:20729976

Rotational multispectral fluorescence lifetime imaging and intravascular ultrasound: bimodal system for intravascular applications

PubMed Central

Ma, Dinglong; Bec, Julien; Yankelevich, Diego R.; Gorpas, Dimitris; Fatakdawala, Hussain; Marcu, Laura

2014-01-01

Abstract. We report the development and validation of a hybrid intravascular diagnostic system combining multispectral fluorescence lifetime imaging (FLIm) and intravascular ultrasound (IVUS) for cardiovascular imaging applications. A prototype FLIm system based on fluorescence pulse sampling technique providing information on artery biochemical composition was integrated with a commercial IVUS system providing information on artery morphology. A customized 3-Fr bimodal catheter combining a rotational side-view fiberoptic and a 40-MHz IVUS transducer was constructed for sequential helical scanning (rotation and pullback) of tubular structures. Validation of this bimodal approach was conducted in pig heart coronary arteries. Spatial resolution, fluorescence detection efficiency, pulse broadening effect, and lifetime measurement variability of the FLIm system were systematically evaluated. Current results show that this system is capable of temporarily resolving the fluorescence emission simultaneously in multiple spectral channels in a single pullback sequence. Accurate measurements of fluorescence decay characteristics from arterial segments can be obtained rapidly (e.g., 20 mm in 5 s), and accurate co-registration of fluorescence and ultrasound features can be achieved. The current finding demonstrates the compatibility of FLIm instrumentation with in vivo clinical investigations and its potential to complement conventional IVUS during catheterization procedures. PMID:24898604

Fluorescence spectroscopy for rapid detection and classification of bacterial pathogens.

PubMed

Sohn, Miryeong; Himmelsbach, David S; Barton, Franklin E; Fedorka-Cray, Paula J

2009-11-01

This study deals with the rapid detection and differentiation of Escherichia coli, Salmonella, and Campylobacter, which are the most commonly identified commensal and pathogenic bacteria in foods, using fluorescence spectroscopy and multivariate analysis. Each bacterial sample cultured under controlled conditions was diluted in physiologic saline for analysis. Fluorescence spectra were collected over a range of 200-700 nm with 0.5 nm intervals on the PerkinElmer Fluorescence Spectrometer. The synchronous scan technique was employed to find the optimum excitation (lambda(ex)) and emission (lambda(em)) wavelengths for individual bacteria with the wavelength interval (Deltalambda) being varied from 10 to 200 nm. The synchronous spectra and two-dimensional plots showed two maximum lambda(ex) values at 225 nm and 280 nm and one maximum lambda(em) at 335-345 nm (lambda(em) = lambda(ex) + Deltalambda), which correspond to the lambda(ex) = 225 nm, Deltalambda = 110-120 nm, and lambda(ex) = 280 nm, Deltalambda = 60-65 nm. For all three bacterial genera, the same synchronous scan results were obtained. The emission spectra from the three bacteria groups were very similar, creating difficulty in classification. However, the application of principal component analysis (PCA) to the fluorescence spectra resulted in successful classification of the bacteria by their genus as well as determining their concentration. The detection limit was approximately 10(3)-10(4) cells/mL for each bacterial sample. These results demonstrated that fluorescence spectroscopy, when coupled with PCA processing, has the potential to detect and to classify bacterial pathogens in liquids. The methodology is rapid (>10 min), inexpensive, and requires minimal sample preparation compared to standard analytical methods for bacterial detection.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-01

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu2+/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu2+ detection is 1 µM for a nanoparticle sample with a diameter of ~30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu2+ ion among the metal ions examined (Na+, K+, Mg2+, Ca2+, Zn2+, Hg2+, Mn2+, Fe2+, Ni2+, Co2+ and Pb2+). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles.

PubMed

Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

2009-09-09

A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu(2+) in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu(2+) ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu(2+) ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu(2+) ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu(2+)/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu(2+) detection is 1 microM for a nanoparticle sample with a diameter of approximately 30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu(2+) ion among the metal ions examined (Na(+), K(+), Mg(2+), Ca(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Ni(2+), Co(2+) and Pb(2+)). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

The use of fluorescent intrabodies to detect endogenous gankyrin in living cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinaldi, Anne-Sophie; Freund, Guillaume; Desplancq, Dominique

2013-04-01

Expression of antibody fragments in mammalian cells (intrabodies) is used to probe the target protein or interfere with its biological function. We previously described the in vitro characterisation of a single-chain Fv (scFv) antibody fragment (F5) isolated from an intrabody library that binds to the oncoprotein gankyrin (GK) in solution. Here, we have isolated several other scFvs that interact with GK in the presence of F5 and tested whether they allow, when fused to fluorescent proteins, to detect by FRET endogenous GK in living cells. The binding of pairs of scFvs to GK was analysed by gel filtration and themore » ability of each scFv to mediate nuclear import/export of GK was determined. Binding between scFv-EGFP and RFP-labelled GK in living cells was detected by fluorescence lifetime imaging microscopy (FLIM). After co-transfection of two scFvs fused to EGFP and RFP, respectively, which form a tri-molecular complex with GK in vitro, FRET signal was measured. This system allowed us to observe that GK is monomeric and distributed throughout the cytoplasm and nucleus of several cancer cell lines. Our results show that pairs of fluorescently labelled intrabodies can be monitored by FLIM–FRET microscopy and that this technique allows the detection of lowly expressed endogenous proteins in single living cells. Highlights: ► Endogenous GK in living cells was targeted with pairs of fluorescently-tagged scFvs. ► Tri-molecular complexes containing two scFvs and one molecule GK were formed. ► GK was detected using fluorescence lifetime-based FRET imaging. ► GK is monomeric and homogeneously distributed in several cancer cell lines. ► This technique may have many applications in live-cell imaging of endogenous proteins.« less

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

NASA Astrophysics Data System (ADS)

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.

Detection of reactive oxygen species (ROS) by the oxidant-sensing probe 2',7'-dichlorodihydrofluorescein diacetate in the cyanobacterium Anabaena variabilis PCC 7937

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rastogi, Rajesh P.; Laboratory of Photobiology and Molecular Microbiology, Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi 221005; Singh, Shailendra P.

2010-07-02

The generation of reactive oxygen species (ROS) under simulated solar radiation (UV-B: 0.30 Wm{sup -2}, UV-A: 25.70 Wm{sup -2} and PAR: 118.06 Wm{sup -2}) was studied in the cyanobacterium Anabaena variabilis PCC 7937 using the oxidant-sensing fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DCFH-DA is a nonpolar dye, converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent DCF when oxidized by intracellular ROS and other peroxides. The images obtained from the fluorescence microscope after 12 h of irradiation showed green fluorescence from cells covered with 295, 320 or 395 nm cut-off filters, indicating themore » generation of ROS in all treatments. However, the green/red fluorescence ratio obtained from fluorescence microscopic analysis showed the highest generation of ROS after UV-B radiation in comparison to PAR or UV-A radiation. Production of ROS was also measured by a spectrofluorophotometer and results obtained supported the results of fluorescence microscopy. Low levels of ROS were detected at the start (0 h) of the experiment showing that they are generated even during normal metabolism. This study also showed that UV-B radiation causes the fragmentation of the cyanobacterial filaments which could be due to the observed oxidative stress. This is the first report for the detection of intracellular ROS in a cyanobacterium by fluorescence microscopy using DCFH-DA and thereby suggesting the applicability of this method in the study of in vivo generation of ROS.« less

Label-free detection of kanamycin based on a G-quadruplex DNA aptamer-based fluorescent intercalator displacement assay

NASA Astrophysics Data System (ADS)

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.

Fluorescence lifetime based bioassays

NASA Astrophysics Data System (ADS)

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.

Fluorescence lifetime spectroscopy in multiple-scattering environments: an application to biotechnology

NASA Astrophysics Data System (ADS)

Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio

1999-07-01

Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.

The role of atomic fluorescence spectrometry in the automatic environmental monitoring of trace element analysis

PubMed Central

Stockwell, P. B.; Corns, W. T.

1993-01-01

Considerable attention has been drawn to the environmental levels of mercury, arsenic, selenium and antimony in the last decade. Legislative and environmental pressure has forced levels to be lowered and this has created an additional burden for analytical chemists. Not only does an analysis have to reach lower detection levels, but it also has to be seen to be correct. Atomic fluorescence detection, especially when coupled to vapour generation techniques, offers both sensitivity and specificity. Developments in the design of specified atomic fluorescence detectors for mercury, for the hydride-forming elements and also for cadmium, are described in this paper. Each of these systems is capable of analysing samples in the part per trillion (ppt) range reliably and economically. Several analytical applications are described. PMID:18924964

A Water-Soluble Fluorescent Probe for SO2 Derivatives in Aqueous Solution and Serum Based on Phenanthroimidazole Dye.

PubMed

Zhou, Yang; Wang, Ying; Xiao, Shuzhang; He, Xiafeng; Zhang, Nuonuo; Li, Dejiang; Zheng, Kaibo

2017-05-01

A water-soluble fluorescent SO 2 derivatives probe PI-SO 2 based on a phenanthroimidazole dye, and a sensitive SO 2 recognition site, aldehyde was constructed. The probe PI-SO 2 exhibits desirable properties such as high sensitivity, high selectivity and good water-solubility. Significantly, we have demonstrated that the probe PI-SO 2 is suitable for rapidly fluorescence detecting of SO 2 derivatives in aqueous solution and serum. The application of the novel probe PI-SO 2 proved that it was not only a useful tool for the detection of SO 2 derivatives in vitro, but also a potential assay for investigating the effects of SO 2 derivatives, and demonstrating its value in practical applicationin of complex biological samples.

Giga-pixel fluorescent imaging over an ultra-large field-of-view using a flatbed scanner.

PubMed

Göröcs, Zoltán; Ling, Yuye; Yu, Meng Dai; Karahalios, Dimitri; Mogharabi, Kian; Lu, Kenny; Wei, Qingshan; Ozcan, Aydogan

2013-11-21

We demonstrate a new fluorescent imaging technique that can screen for fluorescent micro-objects over an ultra-wide field-of-view (FOV) of ~532 cm(2), i.e., 19 cm × 28 cm, reaching a space-bandwidth product of more than 2 billion. For achieving such a large FOV, we modified the hardware and software of a commercially available flatbed scanner, and added a custom-designed absorbing fluorescent filter, a two-dimensional array of external light sources for computer-controlled and high-angle fluorescent excitation. We also re-programmed the driver of the scanner to take full control of the scanner hardware and achieve the highest possible exposure time, gain and sensitivity for detection of fluorescent micro-objects through the gradient index self-focusing lens array that is positioned in front of the scanner sensor chip. For example, this large FOV of our imaging platform allows us to screen more than 2.2 mL of undiluted whole blood for detection of fluorescent micro-objects within <5 minutes. This high-throughput fluorescent imaging platform could be useful for rare cell research and cytometry applications by enabling rapid screening of large volumes of optically dense media. Our results constitute the first time that a flatbed scanner has been converted to a fluorescent imaging system, achieving a record large FOV.

NDE detectability of fatigue type cracks in high strength alloys

NASA Technical Reports Server (NTRS)

Christner, B. K.; Rummel, W. D.

1983-01-01

Specimens suitable for investigating the reliability of production nondestructive evaluation (NDE) to detect tightly closed fatigue cracks in high strength alloys representative of those materials used in spacecraft engine/booster construction were produced. Inconel 718 was selected as representative of nickel base alloys and Haynes 188 was selected as representative of cobalt base alloys used in this application. Cleaning procedures were developed to insure the reusability of the test specimens and a flaw detection reliability assessment of the fluorescent penetrant inspection method was performed using the test specimens produced to characterize their use for future reliability assessments and to provide additional NDE flaw detection reliability data for high strength alloys. The statistical analysis of the fluorescent penetrant inspection data was performed to determine the detection reliabilities for each inspection at a 90% probability/95% confidence level.

pHuji, a pH-sensitive red fluorescent protein for imaging of exo- and endocytosis

PubMed Central

Shen, Yi; Rosendale, Morgane

2014-01-01

Fluorescent proteins with pH-sensitive fluorescence are valuable tools for the imaging of exocytosis and endocytosis. The Aequorea green fluorescent protein mutant superecliptic pHluorin (SEP) is particularly well suited to these applications. Here we describe pHuji, a red fluorescent protein with a pH sensitivity that approaches that of SEP, making it amenable for detection of single exocytosis and endocytosis events. To demonstrate the utility of the pHuji plus SEP pair, we perform simultaneous two-color imaging of clathrin-mediated internalization of both the transferrin receptor and the β2 adrenergic receptor. These experiments reveal that the two receptors are differentially sorted at the time of endocytic vesicle formation. PMID:25385186

Synthesis and cell imaging applications of fluorescent mono/di/tri-heterocyclyl-2,6-dicyanoanilines.

PubMed

Pisal, Mahesh M; Annadate, Ritesh A; Athalye, Meghana C; Kumar, Deepak; Chavan, Subhash P; Sarkar, Dhiman; Borate, Hanumant B

2017-02-15

Synthesis of 3,4,5-triheterocyclyl-2,6-dicyanoanilines, starting from heterocyclic aldehydes and 1,2-diheterocycle-substituted ethanones, is described. 2,6-Dicyanoanilines with one or two heterocyclic substituents have also been synthesized. It was found that some of these molecules have selective cell-staining properties useful for cell imaging applications. The compounds 1g, 10f and 11 were found to stain cytoplasm of the cells in contact but not the nucleus while the compound 12 showed affinity to apoptotic cells resulting in blue fluorescence. The cell imaging results with compound 12 were similar to Annexin V-FITC, a known reagent containing recombinant Annexin V conjugated to green-fluorescent FITC dye, used for detection of apoptotic cells. These compounds were found to be non-cytotoxic and have potential application as cell imaging agents. Copyright © 2016 Elsevier Ltd. All rights reserved.

NUTS and BOLTS: Applications of Fluorescence Detected Sedimentation

PubMed Central

Kroe, Rachel R.; Laue, Thomas M.

2008-01-01

Analytical ultracentrifugation is a widely used method for characterizing the solution behavior of macromolecules. However, the two commonly used detectors (absorbance and interference) impose some fundamental restrictions on the concentrations and complexity of the solutions that can be analyzed. The recent addition of a fluorescence detector for the XL-I analytical ultracentrifuge (AU-FDS) enables two different types of sedimentation experiments. First, the AU-FDS can detect picomolar concentrations of labeled solutes allowing the characterization of very dilute solutions of macromolecules, applications we call Normal Use Tracer Sedimentation (NUTS). The great sensitivity of NUTS analysis allows the characterization of small quantities of materials and high affinity interactions. Second, AU-FDS allows characterization of trace quantities of labeled molecules in solutions containing high concentrations and complex mixtures of unlabeled molecules, applications we call Biological On Line Tracer Sedimentation (BOLTS). The discrimination of BOLTS enables the size distribution of a labeled macromolecule to be determined in biological milieu such as cell lysates and serum. Examples are presented that embody features of both NUTS and BOLTS applications, along with our observations on these applications. PMID:19103145

Fluorescent genetic barcoding in mammalian cells for enhanced multiplexing capabilities in flow cytometry.

PubMed

Smurthwaite, Cameron A; Hilton, Brett J; O'Hanlon, Ryan; Stolp, Zachary D; Hancock, Bryan M; Abbadessa, Darin; Stotland, Aleksandr; Sklar, Larry A; Wolkowicz, Roland

2014-01-01

The discovery of the green fluorescent protein from Aequorea victoria has revolutionized the field of cell and molecular biology. Since its discovery a growing panel of fluorescent proteins, fluorophores and fluorescent-coupled staining methodologies, have expanded the analytical capabilities of flow cytometry. Here, we exploit the power of genetic engineering to barcode individual cells with genes encoding fluorescent proteins. For genetic engineering, we utilize retroviral technology, which allows for the expression of ectopic genetic information in a stable manner in mammalian cells. We have genetically barcoded both adherent and nonadherent cells with different fluorescent proteins. Multiplexing power was increased by combining both the number of distinct fluorescent proteins, and the fluorescence intensity in each channel. Moreover, retroviral expression has proven to be stable for at least a 6-month period, which is critical for applications such as biological screens. We have shown the applicability of fluorescent barcoded multiplexing to cell-based assays that rely themselves on genetic barcoding, or on classical staining protocols. Fluorescent genetic barcoding gives the cell an inherited characteristic that distinguishes it from its counterpart. Once cell lines are developed, no further manipulation or staining is required, decreasing time, nonspecific background associated with staining protocols, and cost. The increasing number of discovered and/or engineered fluorescent proteins with unique absorbance/emission spectra, combined with the growing number of detection devices and lasers, increases multiplexing versatility, making fluorescent genetic barcoding a powerful tool for flow cytometry-based analysis. © 2013 International Society for Advancement of Cytometry.

Paper SERS chromatography for detection of trace analytes in complex samples

NASA Astrophysics Data System (ADS)

Yu, Wei W.; White, Ian M.

2013-05-01

We report the application of paper SERS substrates for the detection of trace quantities of multiple analytes in a complex sample in the form of paper chromatography. Paper chromatography facilitates the separation of different analytes from a complex sample into distinct sections in the chromatogram, which can then be uniquely identified using SERS. As an example, the separation and quantitative detection of heroin in a highly fluorescent mixture is demonstrated. Paper SERS chromatography has obvious applications, including law enforcement, food safety, and border protection, and facilitates the rapid detection of chemical and biological threats at the point of sample.

Detection of alpha-fetoprotein in magnetic immunoassay of thin channels using biofunctional nanoparticles

NASA Astrophysics Data System (ADS)

Tsai, H. Y.; Gao, B. Z.; Yang, S. F.; Li, C. S.; Fuh, C. Bor

2014-01-01

This paper presents the use of fluorescent biofunctional nanoparticles (10-30 nm) to detect alpha-fetoprotein (AFP) in a thin-channel magnetic immunoassay. We used an AFP model biomarker and s-shaped deposition zones to test the proposed detection method. The results show that the detection using fluorescent biofunctional nanoparticle has a higher throughput than that of functional microparticle used in previous experiments on affinity reactions. The proposed method takes about 3 min (versus 150 min of previous method) to detect 100 samples. The proposed method is useful for screening biomarkers in clinical applications, and can reduce the run time for sandwich immunoassays to less than 20 min. The detection limits (0.06 pg/ml) and linear ranges (0.068 pg/ml-0.68 ng/ml) of AFP using fluorescent biofunctional nanoparticles are the same as those of using functional microparticles within experimental errors. This detection limit is substantially lower and the linear range is considerably wider than those of enzyme-linked immunosorbent assay (ELISA) and other methods in sandwich immunoassay methods. The differences between this method and an ELISA in AFP measurements of serum samples were less than 12 %. The proposed method provides simple, fast, and sensitive detection with a high throughput for biomarkers.

Clinical application of a multi-modal endoscope with fluorescent peptide in detection of colorectal neoplasia (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dai, Zhenzhen; Joshi, Bishnu P.; Gao, Zhenghong; Lee, Jeonghoon; Ghimire, Navin; Prabhu, Anoop; Wamsteker, Erik J.; Kwon, Richard S.; Elta, Grace H.; Appelman, Henry D.; Owens, Scott R.; Kuick, Rork; Turgeon, Kim K.; Wang, Thomas D.

2017-02-01

Early detection of precursor lesions for colorectal cancer can greatly improve survival. Pre-neoplasia can appear flat with conventional white light endoscopy. Sessile serrated adenomas (SSA) are precursor lesions found primarily in the proximal colon and frequently appear flat and indistinct. We performed a clinical study of n=37 patients using a multimodal endoscopy with a FITC-labeled peptide specific for SSA. Lesions were imaged with white light, reflectance and fluorescence. White light images were acquired before the peptide was applied and were used to help localize regions of abnormal tissues rightly. Co-registered fluorescence and reflectance images were combined to get ratio images thus the distance was corrected. We calculated the target/background ratio (T/B ratio) to quantify the images and found 2.3-fold greater fluorescence intensity for SSA compared with normal tissues. We found the T/B ratio for SSA to be significantly greater than that for normal colonic mucosa with 89.47% sensitivity and 91.67% specificity at the threshold of 1.22. An ROC curve for SSA and normal mucosa was also plotted with area under curve (AUC) of 0.93. The result also shows that SSA and adenoma are statistically significant and can be identified with 78.95% sensitivity and 90.48% specificity at the threshold of 1.66. An ROC curve was plotted with AUC of 0.88. Therefore, our result shows that the application of a multimodal endoscope with fluorescently labeled peptide can quantify images and works especially good for the detection of SSA which is a premalignant flat lesion conferring a high risk of subsequently leading to a colon cancer.

Antigen detection based on background fluorescence quenching immunochromatographic assay.

PubMed

Chen, Xiangjun; Xu, Yangyang; Yu, Jinsheng; Li, Jiutong; Zhou, Xuelei; Wu, Chuanyong; Ji, Qiuliang; Ren, Yuan; Wang, Liqun; Huang, Zhengyi; Zhuang, Hanling; Piao, Long; Head, Richard; Wang, Yajie; Lou, Jiatao

2014-09-02

Gold immunochromatographic assay (GICA) has been around for quite a while, but it is qualitative in the vast majority of applications. A fast, simple and quantitative GICA is in call for better medicine. In the current study, we have established a novel, quantitative GICA based on fluorescence quenching and nitrocellulose membrane background signals, called background fluorescence quenching immunochromatographic assay (bFQICA). Using model analyte alpha-fetoprotein (AFP), the present study assessed the performance of bFQICA in numerous assay aspects. With serial dilutions of the international AFP standard, standard curves for the calculation of AFP concentration were successfully established. At 10 and 100ngmL(-1) of the international AFP standard, the assay variability was defined with a coefficient of variance at 10.4% and 15.2%, respectively. For samples with extended range of AFP levels, bFQICA was able to detect AFP at as low as 1ngmL(-1). Fluorescence in bFQICA strips stayed constant over months. A good correlation between the results from bFQICA and from a well-established Roche electrochemiluminescence immunoassay was observed in 27 serum samples (r=0.98, p<0.001). In conclusion, our study has demonstrated distinctive features of bFQICA over conventional GICA, including utilization of a unique fluorescence ratio between nitrocellulose membrane background and specific signals (F1/F2) to ensure accurate measurements, combined qualitative and quantitative capabilities, and exceptionally high sensitivity for detection of very low levels of antigens. All of these features could make bFQICA attractive as a model for antigen-antibody complex based GICA, and could promote bFQICA to a broad range of applications for investigation of a variety of diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of flow cytometry with a fluorescent dye to measurement of intracellular nitric oxide in plant cells.

PubMed

Kępczyński, Jan; Cembrowska-Lech, Danuta

2018-04-27

A simple and rapid method involving flow cytometry and NO-specific probe (DAF-FM DA) proved useful for detection and determination of intracellular NO production in Medicago truncatula suspension cells and leaves as well as in cells of Avena fatua, Amaranthus retroflexus embryos and leaves. The measurement of nitric oxide (NO) in plant material is important for examining the regulatory roles of endogenous NO in various physiological processes. The possibility of detecting and determining intracellular NO production by flow cytometry (FCM) with 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM DA), an NO-specific probe in Medicago truncatula cells in suspension and leaves as well as in cells of embryos and leaves of Avena fatua L. or Amaranthus retroflexus L. was explored. To detect and measure NO production by cell suspension or embryos and leaves, the recommended DAF-FM DA concentration is 5 or 10 µM, respectively, applied for 30 min. Exogenous NO increased the intensity of the fluorescent signal in embryos and leaves of both plants, while carboxy-PTIO (cPTIO), an NO scavenger, decreased it. Thus, these results demonstrate that NO can be detected and an increase and a decrease of its intracellular level can be estimated. Wounding was observed to increase the fluorescence signal, indicating an increase in the intracellular NO level. In addition, the levels of exogenous and endogenous ascorbic acid were demonstrated to have no effect on the NO-related fluorescence signal, indicating the signal's specificity only in relation with NO. The applicability of the proposed method for detection and determination of NO was confirmed (1) by in situ NO imaging in cell suspensions and (2) by determining the NO concentration in embryos and leaves using the Griess reagent. In view of the data obtained, FCM is recommended as a rapid and simple method with which to detect and determine intracellular NO production in plant cells.

Ultra-small dye-doped silica nanoparticles via modified sol-gel technique.

PubMed

Riccò, R; Nizzero, S; Penna, E; Meneghello, A; Cretaio, E; Enrichi, F

2018-01-01

In modern biosensing and imaging, fluorescence-based methods constitute the most diffused approach to achieve optimal detection of analytes, both in solution and on the single-particle level. Despite the huge progresses made in recent decades in the development of plasmonic biosensors and label-free sensing techniques, fluorescent molecules remain the most commonly used contrast agents to date for commercial imaging and detection methods. However, they exhibit low stability, can be difficult to functionalise, and often result in a low signal-to-noise ratio. Thus, embedding fluorescent probes into robust and bio-compatible materials, such as silica nanoparticles, can substantially enhance the detection limit and dramatically increase the sensitivity. In this work, ultra-small fluorescent silica nanoparticles (NPs) for optical biosensing applications were doped with a fluorescent dye, using simple water-based sol-gel approaches based on the classical Stöber procedure. By systematically modulating reaction parameters, controllable size tuning of particle diameters as low as 10 nm was achieved. Particles morphology and optical response were evaluated showing a possible single-molecule behaviour, without employing microemulsion methods to achieve similar results. Graphical abstractWe report a simple, cheap, reliable protocol for the synthesis and systematic tuning of ultra-small (< 10 nm) dye-doped luminescent silica nanoparticles.

Indocyanine green detects sentinel lymph nodes in early breast cancer.

PubMed

Liu, Jun; Huang, Linping; Wang, Ning; Chen, Ping

2017-04-01

Objective To explore the clinical value of indocyanine green (ICG) for the fluorescence-guided detection of sentinel lymph nodes (SLNs) during sentinel lymph node biopsy (SLNB) in patients with early breast cancer. Methods This retrospective study included female patients with breast cancer. Patients were administered methylene blue and ICG using standard techniques. All SLNs that were collected during surgery were submitted for pathological examination. SLNs were defined as those that were either fluorescent, blue, fluorescent and blue or palpably suspicious. Surgical complications, axillary recurrence, distant metastasis and overall survival rates were observed postoperatively. Results A total of 60 patients were enrolled in the study. The fluorescence detection rate of SLNs was 100% ( n = 177), with a mean of 2.95 SLNs per patient. The methylene blue staining rate was 88.3% ( n = 106), with a mean of 1.77 SLNs per patient. Pathological assessment of intraoperative frozen specimens revealed SLN metastases in 10 patients, who immediately underwent axillary lymph node dissection. No patient had axillary recurrence or distant metastases, with a survival rate of 100%. Patients who underwent SLNB showed good appearance in the axillary wound, with no limited shoulder joint abduction and upper limb oedema. Conclusion Fluorescence-guided SLNB has several advantages and is suitable for clinical application.

Screening of biologically important Zn2 + by a chemosensor with fluorescent turn on-off mechanism

NASA Astrophysics Data System (ADS)

Khan, Tanveer A.; Sheoran, Monika; Nikhil Raj M., Venkata; Jain, Surbhi; Gupta, Diksha; Naik, Sunil G.

2018-01-01

Reported herein the synthesis, characterization and biologically important zinc ion binding propensity of a weakly fluorescent chemosensor, 4-methyl-2,6-bis((E)-(2-(4-phenylthiazol-2-yl)hydrazono)methyl)phenol (1). 1H NMR spectroscopic titration experiment reveals the binding knack of 1 to the essential Zn2 +. The photo-physical studies of 1 exhibit an enhancement in the fluorescence by several folds upon binding with the zinc ions attributed to PET-off process, with a binding constant value of 5.22 × 103 M- 1. 1 exhibits an excellent detection range for Zn2 + with lower detection limit value of 2.31 × 10- 8 M. The selectivity of 1 was studied with various mono and divalent metal cations and it was observed that most cations either quenches the fluorescence or remains unchanged except for Cd2 +, which shows a slight enhancement in fluorescence intensity of 1. The ratiometric displacement of Cd2 + ions by Zn2 + ions shows an excellent selectivity towards in-situ detection of Zn2 + ions. Photo-physical studies also support the reversible binding of 1 to Zn2 + ions having on and off mechanism in presence of EDTA. Such recognition of the biologically important zinc ions finds potential application in live cell imaging.

A Metal-Polydopamine Framework (MPDA) as an Effective Fluorescent Quencher for Highly Sensitive Detection of Hg (II) And Ag (I) ions Through Exonuclease III Activity.

PubMed

Ravikumar, Ayyanu; Panneerselvam, Perumal; Morad, Norhashimah

2018-05-24

In this paper, we propose a metal-polydopamine framework (MPDA) with specific molecular probe which appears to be the most promising approach to a strong fluorescence quencher. The MPDA framework quenching ability towards various organic fluorophore such as aminoethylcomarin acetate (AMCA), 6-carboxyfluorescein (FAM), carboxyteramethylrhodamine (TAMRA) and Cy5 are used to establish a fluorescent biosensor that can selectively recognize Hg2+ and Ag+ ion. The fluorescent quenching efficiency was sufficient to achieve more than 96%. The MPDA framework also exhibits different affinities with ssDNA and dsDNA. In addition, the FAM labelled ssDNA was adsorbed onto MPDA framework, based on their interaction with the complex formed between MPDA frameworks/ssDNA taken as a sensing platform. By taking advantage of this sensor highly sensitive and selective determination of Hg2+and Ag+ ions is achieved through Exonuclease III signal amplification activity. The detection limits of Hg2+and Ag+ achieved to be 1.2 pM and 34 pM respectively, were compared to co-existing metal ions and GO based sensors. Furthermore, the potential applications of this study establish the highly sensitive fluorescence detection targets in environmental and biological fields.

Particle Image Velocimetry Applications Using Fluorescent Dye-Doped Particles

NASA Technical Reports Server (NTRS)

Petrosky, Brian J.; Maisto, Pietro; Lowe, K. Todd; Andre, Matthieu A.; Bardet, Philippe M.; Tiemsin, Patsy I.; Wohl, Christopher J.; Danehy, Paul M.

2015-01-01

Polystyrene latex sphere particles are widely used to seed flows for velocimetry techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). These particles may be doped with fluorescent dyes such that signals spectrally shifted from the incident laser wavelength may be detected via Laser Induced Fluorescence (LIF). An attractive application of the LIF signal is achieving velocimetry in the presence of strong interference from laser scatter, opening up new research possibilities very near solid surfaces or at liquid/gas interfaces. Additionally, LIF signals can be used to tag different fluid streams to study mixing. While fluorescence-based PIV has been performed by many researchers for particles dispersed in water flows, the current work is among the first in applying the technique to micron-scale particles dispersed in a gas. A key requirement for such an application is addressing potential health hazards from fluorescent dyes; successful doping of Kiton Red 620 (KR620) has enabled the use of this relatively safe dye for fluorescence PIV for the first time. In this paper, basic applications proving the concept of PIV using the LIF signal from KR620-doped particles are exhibited for a free jet and a twophase flow apparatus. Results indicate that while the fluorescence PIV techniques are roughly 2 orders of magnitude weaker than Mie scattering, they provide a viable method for obtaining data in flow regions previously inaccessible via standard PIV. These techniques have the potential to also complement Mie scattering signals, for example in multi-stream and/or multi-phase experiments.

Hypochlorite-Mediated Modulation of Photoinduced Electron Transfer in a Phenothiazine-Boron dipyrromethene Electron Donor-Acceptor Dyad: A Highly Water Soluble "Turn-On" Fluorescent Probe for Hypochlorite.

PubMed

Soni, Disha; Duvva, Naresh; Badgurjar, Deepak; Roy, Tapta Kanchan; Nimesh, Surendra; Arya, Geeta; Giribabu, Lingamallu; Chitta, Raghu

2018-04-16

A highly water-soluble phenothiazine (PTZ)-boron dipyrromethene (BODIPY)-based electron donor-acceptor dyad (WS-Probe), which contains BODIPY as the signaling antennae and PTZ as the OCl - reactive group, was designed and used as a fluorescent chemosensor for the detection of OCl - . Upon addition of incremental amounts of NaOCl, the quenched fluorescence of WS-Probe was enhanced drastically, which indicated the inhibition of reductive photoinduced electron transfer (PET) from PTZ to 1 BODIPY*; the detection limit was calculated to be 26.7 nm. Selectivity studies with various reactive oxygen species, cations, and anions revealed that WS-Probe was able to detect OCl - selectively. Steady-state fluorescence studies performed at varied pH suggested that WS-Probe can detect NaOCl and exhibits maximum fluorescence in the pH range of 7 to 8, similar to physiological conditions. ESI-MS analysis and 1 H NMR spectroscopy titrations showed the formation of sulfoxide as the major oxidized product upon addition of hypochlorite. More interestingly, when WS-Probe was treated with real water samples, the fluorescence response was clearly visible with tap water and disinfectant, which indicated the presence of OCl - in these samples. The in vitro cell viability assay performed with human embryonic kidney 293 (HEK 293) cells suggested that WS-probe is non-toxic up to 10 μm and implicates the use of the probe for biological applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The application of anti-ESAT-6 monoclonal antibody fluorescent probe in ex vivo near-infrared fluorescence imaging in mice with pulmonary tuberculosis.

PubMed

Feng, Feng; Zhang, Haoling; Zhu, Zhaoqin; Li, Cong; Shi, Yuxin; Zhang, Zhiyong

2014-09-01

Here, we aimed to assess the feasibility of anti-ESAT-6 monoclonal antibody (mAb) coupling with IR783 and rhodamine fluorescent probe in the detection of ESAT-6 expression in tuberculosis tissue of mice using near-infrared fluorescence imaging. IR783 and rhodamine were conjugated to the anti-ESAT-6 mAb or IgG. Mice in the experimental group were injected with fluorescence-labeled mAb probe, and mice in the control group were injected with fluorescence-labeled non-specific IgG antibody. Twenty-four hours later, the lung tissue of mice was examined using ex vivo near-infrared fluorescence imaging. In addition, the contrast-to-noise ratio (CNR) was calculated by measuring the signal intensities of the pulmonary lesions, normal lung tissue and background noise. The frozen lung tissue section was examined under fluorescence microscopy and compared with hemoxylin and eosin (HE) staining. The ex vivo near-infrared fluorescence imaging showed that the fluorescence signal in the lung tuberculosis lesions in the experimental group was significantly enhanced, whereas there was only a weak fluorescence signal or even no fluorescence signal in the control group. CNR values were 64.40 ± 7.02 (n = 6) and 8.75 ± 3.87 (n = 6), respectively (t = 17.01, p < 0.001). The fluorescence accumulation distribution detected under fluorescence microscopy was consistent with HE staining of the tuberculosis region. In conclusion, anti-ESAT-6 mAb fluorescent probe could target and be applied in specific ex vivo imaging of mice tuberculosis, and may be of further use in tuberculosis in living mice. Copyright © 2013 John Wiley & Sons, Ltd.

Fluorescence lifetime measurements in flow cytometry

NASA Astrophysics Data System (ADS)

Beisker, Wolfgang; Klocke, Axel

1997-05-01

Fluorescence lifetime measurements provide insights int eh dynamic and structural properties of dyes and their micro- environment. The implementation of fluorescence lifetime measurements in flow cytometric systems allows to monitor large cell and particle populations with high statistical significance. In our system, a modulated laser beam is used for excitation and the phase shift of the fluorescence signal recorded with a fast computer controlled digital oscilloscope is processed digitally to determine the phase shift with respect to a reference beam by fast fourier transform. Total fluorescence intensity as well as other parameters can be determined simultaneously from the same fluorescence signal. We use the epi-illumination design to allow the use of high numerical apertures to collect as much light as possible to ensure detection of even weak fluorescence. Data storage and processing is done comparable to slit-scan flow cytometric data using data analysis system. The results are stored, displayed, combined with other parameters and analyzed as normal listmode data. In our report we discuss carefully the signal to noise ratio for analog and digital processed lifetime signals to evaluate the theoretical minimum fluorescence intensity for lifetime measurements. Applications to be presented include DNA staining, parameters of cell functions as well as different applications in non-mammalian cells such as algae.

Lifetime fluorescence spectroscopy for in situ investigation of osteogenic differentiation

NASA Astrophysics Data System (ADS)

Marcu, Laura; Elbarbary, Amir; Zuk, Patricia; De Ugarte, Daniel A.; Benhaim, Prosper; Kurt, Hamza; Hedrick, Marc H.; Ashjian, Peter

2003-07-01

Time-Resolved Laser-Induced Fluorescence Spectroscopy (TR-LIFS) represents a potential tool for the in-situ characterization of bioengineered tissues. In this study, we evaluate the application of TR-LIFS to non-intrusive monitoring of matrix composition during osteogenetic differentiation. Human adipose-derived stem cells, harvested from 3 patients, were induced in osteogenic media for 3, 5, and 7 weeks. Samples were subsequently collected and probed for time-resolved fluorescence emission with a pulsed nitrogen laser. Fluorescence parameters, derived from both spectral- and time-domain, were used for sample characterization. The samples were further analyzed using Western blot analysis and computer-based densitometry. A significant change in the fluorescence parameters was detected for samples beyond 3 weeks of osteogenic differentiation. The spectroscopic observations: 1) show increase of collagen I when contrasted against the time-resolved fluorescence spectra of commercially available collagens; and 2) are in agreement with Western blot analysis that demonstrated significant increase in collagen I content between 3- vs. 5-weeks and 3- vs. 7-weeks and no changes for collagens III, IV, and V. Our results suggest that TR-LIFS can be used as a non-invasive means for the detection of specific collagens in maturing connective tissues.

Utilizing hyaluronic acid as a versatile platform for fluorescence resonance energy transfer-based glucose sensing.

PubMed

Ge, Minghao; Bai, Pengli; Chen, Mingli; Tian, Jingjing; Hu, Jun; Zhi, Xu; Yin, Huancai; Yin, Jian

2018-03-01

Here, we utilized the ultrasonic emulsification technique to generate hyaluronic acid microspheres incorporating a fluorescence-based glucose biosensor. We synthesized a novel lanthanide ion luminophore based on Eu 3+ . Eu sulfosuccinimidyl dextran (Eu-dextran) and Alexa Fluor 647 sulfosuccinimidyl-ConA (Alexa Fluor 647-ConA) were encapsulated in hyaluronic acid hydrogel to generate microspheres. Glucose sensing was carried out using a fluorescence resonance energy transfer (FRET)-based assay principle. A proportional fluorescence intensity increase was found within a 0.5-10-mM glucose concentration range. The glucose-sensing strategy showed an excellent tolerance for potential interferents. Meanwhile, the fluorescent signal of hyaluronic acid microspheres was very stable after testing for 72 h in glucose solution. Overall, hyaluronic acid microspheres encapsulating sensing biomolecules offer a stable and biocompatible biosensor for a variety of applications including cell culture systems, tissue engineering, detection of blood glucose, etc. Graphical abstract We report an ingenious biosensor encapsulated in hyaluronic acid microspheres for monitoring of glucose. Glucose sensing is carried out using a fluorescence resonance energy transfer-based assay principle with a novel lanthanide ions luminophore. The glucose detection system has excellent biocompatibility and stability for monitoring of glucose.

Utility of Experimental Design in Pre-Column Derivatization for the Analysis of Tobramycin by HPLC-Fluorescence Detection: Application to Ophthalmic Solution and Human Plasma.

PubMed

El-Zaher, Asmaa A; Mahrouse, Marianne A

2013-01-01

A novel, selective, and sensitive reversed phase high-performance liquid chromatography (HPLC) method coupled with fluorescence detection has been developed for the determination of tobramycin (TOB) in pure form, in ophthalmic solution and in spiked human plasma. Since TOB lacks UV absorbing chromophores and native fluorescence, pre-column derivatization of TOB was carried out using fluorescamine reagent (0.01%, 1.5 mL) and borate buffer (pH 8.5, 2 mL). Experimental design was applied for optimization of the derivatization step. The resulting highly fluorescent stable derivative was chromatographed on C18 column and eluted using methanol:water (60:40, v/v) at a flow rate of 1 mL min(-1). A fluorescence detector (λex 390 and λem 480 nm) was used. The method was linear over the concentration range 20-200 ng mL(-1). The structure of the fluorescent product was proposed, the method was then validated and applied for the determination of TOB in human plasma. The results were statistically compared with the reference method, revealing no significant difference.

Utility of Experimental Design in Pre-Column Derivatization for the Analysis of Tobramycin by HPLC—Fluorescence Detection: Application to Ophthalmic Solution and Human Plasma

PubMed Central

El-Zaher, Asmaa A.; Mahrouse, Marianne A.

2013-01-01

A novel, selective, and sensitive reversed phase high-performance liquid chromatography (HPLC) method coupled with fluorescence detection has been developed for the determination of tobramycin (TOB) in pure form, in ophthalmic solution and in spiked human plasma. Since TOB lacks UV absorbing chromophores and native fluorescence, pre-column derivatization of TOB was carried out using fluorescamine reagent (0.01%, 1.5 mL) and borate buffer (pH 8.5, 2 mL). Experimental design was applied for optimization of the derivatization step. The resulting highly fluorescent stable derivative was chromatographed on C18 column and eluted using methanol:water (60:40, v/v) at a flow rate of 1 mL min−1. A fluorescence detector (λex 390 and λem 480 nm) was used. The method was linear over the concentration range 20–200 ng mL−1. The structure of the fluorescent product was proposed, the method was then validated and applied for the determination of TOB in human plasma. The results were statistically compared with the reference method, revealing no significant difference. PMID:23700362

Synthesizing a nano-composite of BSA-capped Au nanoclusters/graphitic carbon nitride nanosheets as a new fluorescent probe for dopamine detection.

PubMed

Guo, Xinrong; Wu, Fangying; Ni, Yongnian; Kokot, Serge

2016-10-26

A strong red fluorescent nanocomposite, consisting of graphite-like carbon nitride nanosheets (g-C 3 N 4 NSs) and serum albumin-capped Au nanoclusters (AuNCs), was synthesized. Dopamine (DA) can quench the red fluorescence of the nanocomposite, based on the Forster resonance energy transfer (FRET) mechanism. In this quenching process, the energy is transferred from the fluorescent g-C 3 N 4 NSs-AuNCs to the oxidized DA quinine molecules (DA is easily oxidated to form DA quinine in air). The red fluorescence emission at 420 nm decreases dramatically and the quenching ratio (F 0 - F)/F 0 is linearly related to the concentration of DA in the range of 0.05-8.0 μmol L -1 with a detection limit of 0.018 μmol L -1  (S/N = 3). Additionally, this sensor has a potential of application to assay the DA in the real samples, such as human serum and human urine. Copyright © 2016 Elsevier B.V. All rights reserved.

A simple fluorescent probe for the fast sequential detection of copper and biothiols based on a benzothiazole derivative

NASA Astrophysics Data System (ADS)

Shen, Youming; Zhang, Xiangyang; Zhang, Chunxiang; Zhang, Youyu; Jin, Junling; Li, Haitao

2018-02-01

A simple benzothiazole fluorescent chemosensor was developed for the fast sequential detection of Cu2 + and biothiols through modulating the excited-state intramolecular proton transfer (ESIPT) process. The compound 1 exhibits highly selective and sensitive fluorescence ;on-off; recognition to Cu2 + with a 1:1 binding stoichiometry by ESIPT hinder. The in situ generated 1-Cu2 + complex can serve as an ;on-off; fluorescent probe for high selectivity toward biothiols via Cu2 + displacement approach, which exerts ESIPT recovery. It is worth pointing out that the 1-Cu2 + complex shows faster for cysteins (within 1 min) than other biothiols such as homocysteine (25 min) and glutathione (25 min). Moreover, the compound 1 displays 160 nm Stoke-shift for reversibly monitoring Cu2 + and biothiols. In addition, the probe is successfully used for fluorescent cellular imaging. This strategy via modulation the ESIPT state has been used for determination of Cu2 + and Cys with satisfactory results, which further demonstrates its value of practical applications.

Fluorescence-based bioassays for the detection and evaluation of food materials.

PubMed

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.

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

PubMed Central

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 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. PMID:26473869

A real-time fluorescence assay for protease activity and inhibitor screening based on the aggregation-caused quenching of a perylene probe.

PubMed

Wang, Yan; Zhang, Zhifang; Zhang, Ya; Yu, Cong

2018-06-01

We have established a real-time and label-free fluorescence turn-on strategy for protease activity detection and inhibitor screening via peptide-induced aggregation-caused quenching of a perylene probe. Because of electrostatic interactions and high hydrophilicity, poly-l-glutamic acid sodium salt (PGA; a negatively charged peptide) could induce aggregation of a positively charged perylene probe (probe 1) and the monomer fluorescence of probe 1 was effectively quenched. After a protease was added, PGA was enzymatically hydrolyzed into small fragments and probe 1 disaggregated. The fluorescence recovery of probe 1 was found to be proportional to the concentration of protease in the range from 0 to 1 mU/ml. The detection limit was down to 0.1 mU/ml. In the presence of a protease inhibitor, protease activity was inhibited and fluorescence recovery reduced. Moreover, we demonstrated the potential application of our method in a complex mixture sample including 1% human serum. Our method is simple, fast and cost effective. Copyright © 2018 John Wiley & Sons, Ltd.

AUTOMATED CELL SEGMENTATION WITH 3D FLUORESCENCE MICROSCOPY IMAGES.

PubMed

Kong, Jun; Wang, Fusheng; Teodoro, George; Liang, Yanhui; Zhu, Yangyang; Tucker-Burden, Carol; Brat, Daniel J

2015-04-01

A large number of cell-oriented cancer investigations require an effective and reliable cell segmentation method on three dimensional (3D) fluorescence microscopic images for quantitative analysis of cell biological properties. In this paper, we present a fully automated cell segmentation method that can detect cells from 3D fluorescence microscopic images. Enlightened by fluorescence imaging techniques, we regulated the image gradient field by gradient vector flow (GVF) with interpolated and smoothed data volume, and grouped voxels based on gradient modes identified by tracking GVF field. Adaptive thresholding was then applied to voxels associated with the same gradient mode where voxel intensities were enhanced by a multiscale cell filter. We applied the method to a large volume of 3D fluorescence imaging data of human brain tumor cells with (1) small cell false detection and missing rates for individual cells; and (2) trivial over and under segmentation incidences for clustered cells. Additionally, the concordance of cell morphometry structure between automated and manual segmentation was encouraging. These results suggest a promising 3D cell segmentation method applicable to cancer studies.

Highly Sensitive Detection of Glucose by a "Turn-Off-On" Fluorescent Probe Using Gadolinium-Doped Carbon Dots and Carbon Microparticles.

PubMed

Hu, Meixin; Qi, Jianrong; Ruan, Jing; Shen, Guangxia

2018-06-01

Carbon dots, as a potential substitute for semiconductor quantum dots, have drawn great interest in recent years. The preparation of fluorescent carbon dots has been made easy with many significant advances, but the complicated purifying processes, low quantum yield, and blue emission wavelength still limit its wider application in biosensors, biomedicine, and photonic devices. Here we report a strategy to synthesis Gd-doped carbon dots (Gd-Cdots) of super-high quantum yield with a microwave assisted hydrothermal method. The Gd-Cdots, with a diameter of 47∼8 nm, can be purified easily with conventional centrifugal techniques. Carbon microparticles (CMPs) have also been synthesized with a similar procedure. Meanwhile, we demonstrated a novel "turn-off-on" fluorescent biosensor, which has been developed for highly sensitive detection of glucose using Gd-doped carbon dots as probes. The proposed biosensor has exhibited low-cost and non-toxic properties, with high sensitivity and good specificity. In addition, the results in real blood samples further confirmed it as a promising application in diabetes diagnosis.

Fluorescence detection, enumeration and characterization of single circulating cells in vivo: technology, applications and future prospects

NASA Astrophysics Data System (ADS)

Hartmann, Carolin; Patil, Roshani; Lin, Charles P.; Niedre, Mark

2018-01-01

There are many diseases and biological processes that involve circulating cells in the bloodstream, such as cancer metastasis, immunology, reproductive medicine, and stem cell therapies. This has driven significant interest in new technologies for the study of circulating cells in small animal research models and clinically. Most currently used methods require drawing and enriching blood samples from the body, but these suffer from a number of limitations. In contrast, ‘in vivo flow cytometry’ (IVFC) refers to set of technologies that allow study of cells directly in the bloodstream of the organism in vivo. In recent years the IVFC field has grown significantly and new techniques have been developed, including fluorescence microscopy, multi-photon, photo-acoustic, and diffuse fluorescence IVFC. In this paper we review recent technical advances in IVFC, with emphasis on instrumentation, contrast mechanisms, and detection sensitivity. We also describe key applications in biomedical research, including cancer research and immunology. Last, we discuss future directions for IVFC, as well as prospects for broader adoption by the biomedical research community and translation to humans clinically.

Fluorescence detection, enumeration and characterization of single circulating cells in vivo: technology, applications and future prospects.

PubMed

Hartmann, Carolin; Patil, Roshani; Lin, Charles P; Niedre, Mark

2017-12-14

There are many diseases and biological processes that involve circulating cells in the bloodstream, such as cancer metastasis, immunology, reproductive medicine, and stem cell therapies. This has driven significant interest in new technologies for the study of circulating cells in small animal research models and clinically. Most currently used methods require drawing and enriching blood samples from the body, but these suffer from a number of limitations. In contrast, 'in vivo flow cytometry' (IVFC) refers to set of technologies that allow study of cells directly in the bloodstream of the organism in vivo. In recent years the IVFC field has grown significantly and new techniques have been developed, including fluorescence microscopy, multi-photon, photo-acoustic, and diffuse fluorescence IVFC. In this paper we review recent technical advances in IVFC, with emphasis on instrumentation, contrast mechanisms, and detection sensitivity. We also describe key applications in biomedical research, including cancer research and immunology. Last, we discuss future directions for IVFC, as well as prospects for broader adoption by the biomedical research community and translation to humans clinically.

Fluorescence based Aptasensors for the determination of hepatitis B virus e antigen.

PubMed

Huang, Rongrong; Xi, Zhijiang; Deng, Yan; He, Nongyue

2016-08-08

This research is aimed at selecting specific aptamer of hepatitis B e antigen by SELEX and its applications. Hepatitis B e antigen (HBeAg) seroconversion is used as an indicator of virological response when treating patients suffering from chronic hepatitis B. HBeAg also indicates a high viremia and high infectivity in untreated patients. With HBeAg modified magnetic beads as targets, three groups of aptamers are successfully selected. These are the first reported DNA aptamers that can specifically bind to HBeAg. Based on the property that the conformation changes upon binding to its target, aptamer has emerged as ideal candidate in a variety of sensing applications. In this study, we present a simple strategy for aptamer-based fluorescence biosensors for the quantitative detection of HBeAg, in which a fluorescence labeled HBeAg aptamer serves as the molecular recognition element and a short DNA molecule that is complementary to the aptamer serves as the competitor. The LOD for HBeAg is 609 ng/mL. Later, the fluorescence system is deployed in HBeAg positive and negative blood serum (p < 0.05). The total detection assay could be completed in 2 min. These newly isolated aptamers could assist the diagnosis of chronic hepatitis B.

Fluorescence based Aptasensors for the determination of hepatitis B virus e antigen

PubMed Central

Huang, Rongrong; Xi, Zhijiang; Deng, Yan; He, Nongyue

2016-01-01

This research is aimed at selecting specific aptamer of hepatitis B e antigen by SELEX and its applications. Hepatitis B e antigen (HBeAg) seroconversion is used as an indicator of virological response when treating patients suffering from chronic hepatitis B. HBeAg also indicates a high viremia and high infectivity in untreated patients. With HBeAg modified magnetic beads as targets, three groups of aptamers are successfully selected. These are the first reported DNA aptamers that can specifically bind to HBeAg. Based on the property that the conformation changes upon binding to its target, aptamer has emerged as ideal candidate in a variety of sensing applications. In this study, we present a simple strategy for aptamer-based fluorescence biosensors for the quantitative detection of HBeAg, in which a fluorescence labeled HBeAg aptamer serves as the molecular recognition element and a short DNA molecule that is complementary to the aptamer serves as the competitor. The LOD for HBeAg is 609 ng/mL. Later, the fluorescence system is deployed in HBeAg positive and negative blood serum (p < 0.05). The total detection assay could be completed in 2 min. These newly isolated aptamers could assist the diagnosis of chronic hepatitis B. PMID:27499342

Development of magnetic luminescent core/shell nanocomplex particles with fluorescence using Rhodamine 6G

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hee Uk; Song, Yoon Seok; Park, Chulhwan

2012-12-15

Graphical abstract: Display Omitted Highlights: ► A simple method was developed to synthesize Co-B/SiO{sub 2}/dye/SiO{sub 2} composite particles. ► The magnetic particle shows that highly luminescent and core/shell particles are formed. ► Such core/shell particles can be easily suspended in water. ► The magnetic particles could detect fluorescence for the application of biosensor. -- Abstract: A simple and reproducible method was developed to synthesize a novel class of Co-B/SiO{sub 2}/dye/SiO{sub 2} composite core/shell particles. Using a single cobalt core, Rhodamine 6G of organic dye molecules was entrapped in a silica shell, resulting in core/shell particles of ∼200 nm diameter. Analysesmore » using a variety of techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, vibration sample magnetometry, confocal laser scanning microscopy, and fluorescence intensity demonstrated that dye molecules were trapped inside the core/shell particles. A photoluminescence investigation showed that highly luminescent and photostable core/shell particles were formed. Such core/shell particles can be easily suspended in water. The synthesized magnetic particles could be used to detect fluorescence on glass substrate arrays for bioassay and biosensor applications.« less

Compact and cost effective instrument for detecting drug precursors in different environments based on fluorescence polarization

NASA Astrophysics Data System (ADS)

Antolín-Urbaneja, J. C.; Eguizabal, I.; Briz, N.; Dominguez, A.; Estensoro, P.; Secchi, A.; Varriale, A.; Di Giovanni, S.; D'Auria, S.

2013-05-01

Several techniques for detecting chemical drug precursors have been developed in the last decade. Most of them are able to identify molecules at very low concentration under lab conditions. Other commercial devices are able to detect a fixed number and type of target substances based on a single detection technique providing an absence of flexibility with respect to target compounds. The construction of compact and easy to use detection systems providing screening for a large number of compounds being able to discriminate them with low false alarm rate and high probability of detection is still an open concern. Under CUSTOM project, funded by the European Commission within the FP7, a stand-alone portable sensing device based on multiple techniques is being developed. One of these techniques is based on the LED induced fluorescence polarization to detect Ephedrine and Benzyl Methyl Keton (BMK) as a first approach. This technique is highly selective with respect to the target compounds due to the generation of properly engineered fluorescent proteins which are able to bind the target analytes, as it happens in an "immune-type reaction". This paper deals with the advances in the design, construction and validation of the LED induced fluorescence sensor to detect BMK analytes. This sensor includes an analysis module based on high performance LED and PMT detector, a fluidic system to dose suitable quantities of reagents and some printed circuit boards, all of them fixed in a small structure (167mm × 193mm × 228mm) with the capability of working as a stand-alone application.

Quantum Dot Enabled Molecular Sensing and Diagnostics

PubMed Central

Zhang, Yi; Wang, Tza-Huei

2012-01-01

Since its emergence, semiconductor nanoparticles known as quantum dots (QDs) have drawn considerable attention and have quickly extended their applicability to numerous fields within the life sciences. This is largely due to their unique optical properties such as high brightness and narrow emission band as well as other advantages over traditional organic fluorophores. New molecular sensing strategies based on QDs have been developed in pursuit of high sensitivity, high throughput, and multiplexing capabilities. For traditional biological applications, QDs have already begun to replace traditional organic fluorophores to serve as simple fluorescent reporters in immunoassays, microarrays, fluorescent imaging applications, and other assay platforms. In addition, smarter, more advanced QD probes such as quantum dot fluorescence resonance energy transfer (QD-FRET) sensors, quenching sensors, and barcoding systems are paving the way for highly-sensitive genetic and epigenetic detection of diseases, multiplexed identification of infectious pathogens, and tracking of intracellular drug and gene delivery. When combined with microfluidics and confocal fluorescence spectroscopy, the detection limit is further enhanced to single molecule level. Recently, investigations have revealed that QDs participate in series of new phenomena and exhibit interesting non-photoluminescent properties. Some of these new findings are now being incorporated into novel assays for gene copy number variation (CNV) studies and DNA methylation analysis with improved quantification resolution. Herein, we provide a comprehensive review on the latest developments of QD based molecular diagnostic platforms in which QD plays a versatile and essential role. PMID:22916072

A new visible-light-excitable ICT-CHEF-mediated fluorescence 'turn-on' probe for the selective detection of Cd(2+) in a mixed aqueous system with live-cell imaging.

PubMed

Goswami, Shyamaprosad; Aich, Krishnendu; Das, Sangita; Das Mukhopadhyay, Chitrangada; Sarkar, Deblina; Mondal, Tapan Kumar

2015-03-28

A new quinoline based sensor was developed and applied for the selective detection of Cd(2+) both in vitro and in vivo. The designed probe displays a straightforward approach for the selective detection of Cd(2+) with a prominent fluorescence enhancement along with a large red shift (∼38 nm), which may be because of the CHEF (chelation-enhanced fluorescence) and ICT (internal charge transfer) processes after interaction with Cd(2+). The interference from other biologically important competing metal ions, particularly Zn(2+), has not been observed. The visible-light excitability of the probe merits in the viewpoint of its biological application. The probe enables the detection of intracellular Cd(2+) with non-cytotoxic effects, which was demonstrated with the live RAW cells. The experimentally observed change in the structure and electronic properties of the sensor after the addition of Cd(2+) were modelled by the density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations, respectively. Moreover, the test strip experiment with this sensor exhibits both absorption and fluorescence color changes when exposed to Cd(2+) in a mixed aqueous solution, which also makes the probe more useful. The minimum limit of detection of Cd(2+) by the probe was in the range of 9.9 × 10(-8) M level.

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

PubMed

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.

Concise and Efficient Fluorescent Probe via an Intromolecular Charge Transfer for the Chemical Warfare Agent Mimic Diethylchlorophosphate Vapor Detection.

PubMed

Yao, Junjun; Fu, Yanyan; Xu, Wei; Fan, Tianchi; Gao, Yixun; He, Qingguo; Zhu, Defeng; Cao, Huimin; Cheng, Jiangong

2016-02-16

Sarin, used as chemical warfare agents (CWAs) for terrorist attacks, can induce a number of virulent effects. Therefore, countermeasures which could realize robust and convenient detection of sarin are in exigent need. A concise charge-transfer colorimetric and fluorescent probe (4-(6-(tert-butyl)pyridine-2-yl)-N,N-diphenylaniline, TBPY-TPA) that could be capable of real-time and on-site monitoring of DCP vapor was reported in this contribution. Upon contact with DCP, the emission band red-shifted from 410 to 522 nm upon exposure to DCP vapor. And the quenching rate of TBPY-TPA reached up to 98% within 25 s. Chemical substances such as acetic acid (HAc), dimethyl methylphosphonate (DMMP), pinacolyl methylphosphonate (PAMP), and triethyl phosphate (TEP) do not interfere with the detection. A detection limit for DCP down to 2.6 ppb level is remarkably achieved which is below the Immediately Dangerous to Life or Health concentration. NMR data suggested that a transformation of the pyridine group into pyridinium salt via a cascade reaction is responsible for the sensing process which induced the dramatic fluorescent red shift. All of these data suggest TBPY-TPA is a promising fluorescent sensor for a rapid, simple, and low-cost method for DCP detection, which could be easy to prepare as a portable chemosensor kit for its practical application in real-time and on-site monitoring.

Potential of activatable FAP-targeting immunoliposomes in intraoperative imaging of spontaneous metastases.

PubMed

Tansi, Felista L; Rüger, Ronny; Böhm, Claudia; Kontermann, Roland E; Teichgraeber, Ulf K; Fahr, Alfred; Hilger, Ingrid

2016-05-01

Despite intensive research and medical advances met, metastatic disease remains the most common cause of death in cancer patients. This results from late diagnosis, poor therapeutic response and undetected micrometastases and tumor margins during surgery. One approach to overcome these challenges involves fluorescence imaging, which exploits the properties of fluorescent probes for diagnostic detection of molecular structures at the onset of transformation and for intraoperative detection of metastases and tumor margins in real time. Considering these benefits, many contrast agents suitable for fluorescence imaging have been reported. However, most reports only demonstrate the detection of primary tumors and not the detection of metastases or their application in models of image-guided surgery. In this work, we demonstrate the influence of fibroblast activation protein (FAP) on the metastatic potential of fibrosarcoma cells and elucidate the efficacy of activatable FAP-targeting immunoliposomes (FAP-IL) for image-guided detection of the spontaneous metastases in mice models. Furthermore, we characterized the biodistribution and cellular localization of the liposomal fluorescent components in mice organs and traced their excretion over time in urine and feces. Taken together, activatable FAP-IL enhances intraoperative imaging of metastases. Their high accumulation in metastases, subsequent localization in the bile canaliculi and liver kupffer cells and suitable excretion in feces substantiates their potency as contrast agents for intraoperative imaging. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Highly selective and sensitive macrocycle-based dinuclear foldamer for fluorometric and colorimetric sensing of citrate in water.

PubMed

Rhaman, Md Mhahabubur; Hasan, Mohammad H; Alamgir, Azmain; Xu, Lihua; Powell, Douglas R; Wong, Bryan M; Tandon, Ritesh; Hossain, Md Alamgir

2018-01-10

The selective detection of citrate anions is essential for various biological functions in living systems. A quantitative assessment of citrate is required for the diagnosis of various diseases in the human body; however, it is extremely challenging to develop efficient fluorescence and color-detecting molecular probes for sensing citrate in water. Herein, we report a macrocycle-based dinuclear foldamer (1) assembled with eosin Y (EY) that has been studied for anion binding by fluorescence and colorimetric techniques in water at neutral pH. Results from the fluorescence titrations reveal that the 1·EY ensemble strongly binds citrate anions, showing remarkable selectivity over a wide range of inorganic and carboxylate anions. The addition of citrate anions to the 1·EY adduct led to a large fluorescence enhancement, displaying a detectable color change under both visible and UV light in water up to 2 μmol. The biocompatibility of 1·EY as an intracellular carrier in a biological system was evaluated on primary human foreskin fibroblast (HF) cells, showing an excellent cell viability. The strong binding properties of the ensemble allow it to be used as a highly sensitive, detective probe for biologically relevant citrate anions in various applications.

A water-soluble conjugated polymer for protein identification and denaturation detection.

PubMed

Xu, Qingling; Wu, Chunxian; Zhu, Chunlei; Duan, Xinrui; Liu, Libing; Han, Yuchun; Wang, Yilin; Wang, Shu

2010-12-03

Rapid and sensitive methods to detect proteins and protein denaturation have become increasingly needful in the field of proteomics, medical diagnostics, and biology. In this paper, we have reported the synthesis of a new cationic water-soluble conjugated polymer that contains fluorene and diene moieties in the backbone (PFDE) for protein identification by sensing an array of PFDE solutions in different ionic strengths using the linear discriminant analysis technique (LDA). The PFDE can form complexes with proteins by electrostatic and/or hydrophobic interactions and exhibits different fluorescence response. Three main factors contribute to the fluorescence response of PFDE, namely, the net charge density on the protein surface, the hydrophobic nature of the protein, and the metalloprotein characteristics. The denaturation of proteins can also be detected using PFDE as a fluorescent probe. The interactions between PFDE and proteins were also studied by dynamic light scattering (DLS) and isothermal titration microcalorimetry (ITC) techniques. In contrast to other methods based on conjugated polymers, the synthesis of a series of quencher or dye-labeled acceptors or protein substrates has been avoided in our method, which significantly reduces the cost and the synthetic complexity. Our method provides promising applications on protein identification and denaturation detection in a simple, fast, and label-free manner based on non-specific interaction-induced perturbation of PFDE fluorescence response.

A novel magneto-DNA duplex probe for bacterial DNA detection based on exonuclease III-aided cycling amplification.

PubMed

Zeng, Yan; Wan, Yi; Zhang, Dun; Qi, Peng

2015-01-01

A novel magneto-DNA duplex probe for bacterial DNA detection based on exonuclease III (Exo-III) aided cycling amplification has been developed. This magneto-DNA duplex probe contains a partly hybrid fluorophore-modified capture probe and a fluorophore-modified signal probe with magnetic microparticle as carrier. In the presence of a perfectly matched target bacterial DNA, blunt 3'-terminus of the capture probe is formed, activating the Exo-III aided cycling amplification. Thus, Exo-III catalyzes the stepwise removal of mononucleotides from this terminus, releasing both fluorophore-modified signal probe, fluorescent dyes of the capture probe and target DNA. The released target DNA then starts a new cycle, while released fluorescent fragments are recovered with magnetic separation for fluorescence signal collection. This system exhibited sensitive detection of bacterial DNA, with a detection limit of 14 pM because of the unique cleavage function of Exo-III, high fluorescence intensity, and separating function of magneto-DNA duplex probes. Besides this sensitivity, this strategy exhibited excellent selectivity with mismatched bacterial DNA targets and other bacterial species targets and good applicability in real seawater samples, hence, this strategy could be potentially used for qualitative and quantitative analysis of bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of new photon-counting detectors for single-molecule fluorescence microscopy.

PubMed

Michalet, X; Colyer, R A; Scalia, G; Ingargiola, A; Lin, R; Millaud, J E; Weiss, S; Siegmund, Oswald H W; Tremsin, Anton S; Vallerga, John V; Cheng, A; Levi, M; Aharoni, D; Arisaka, K; Villa, F; Guerrieri, F; Panzeri, F; Rech, I; Gulinatti, A; Zappa, F; Ghioni, M; Cova, S

2013-02-05

Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level.

Development of new photon-counting detectors for single-molecule fluorescence microscopy

PubMed Central

Michalet, X.; Colyer, R. A.; Scalia, G.; Ingargiola, A.; Lin, R.; Millaud, J. E.; Weiss, S.; Siegmund, Oswald H. W.; Tremsin, Anton S.; Vallerga, John V.; Cheng, A.; Levi, M.; Aharoni, D.; Arisaka, K.; Villa, F.; Guerrieri, F.; Panzeri, F.; Rech, I.; Gulinatti, A.; Zappa, F.; Ghioni, M.; Cova, S.

2013-01-01

Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level. PMID:23267185

A sensitive and rapid determination of ranitidine in human plasma by HPLC with fluorescence detection and its application for a pharmacokinetic study.

PubMed

Ulu, Sevgi Tatar; Tuncel, Muzaffer

2012-04-01

A novel precolumn derivatization reversed-phase high-performance liquid chromatography method with fluorescence detection is described for the determination of ranitidine in human plasma. The method was based on the reaction of ranitidine with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole forming yellow colored fluorescent product. The separation was achieved on a C(18) column using methanol-water (60:40, v/v) mobile phase. Fluorescence detection was used at the excitation and emission of 458 and 521 nm, respectively. Lisinopril was utilized as an internal standard. The flow rate was 1.2 mL/min. Ranitidine and lisinopril appeared at 3.24 and 2.25 min, respectively. The method was validated for system suitability, precision, accuracy, linearity, limit of detection, limit of quantification, recovery and robustness. Intra- and inter-day precisions of the assays were in the range of 0.01-0.44%. The assay was linear over the concentration range of 50-2000 ng/mL. The mean recovery was determined to be 96.40 ± 0.02%. This method was successfully applied to a pharmacokinetic study after oral administration of a dose (150 mg) of ranitidine. © The Author [2012]. Published by Oxford University Press. All rights reserved.

Synergistic Combination of Unquenching and Plasmonic Fluorescence Enhancement in Fluorogenic Nucleic Acid Hybridization Probes.

PubMed

Vietz, Carolin; Lalkens, Birka; Acuna, Guillermo P; Tinnefeld, Philip

2017-10-11

Fluorogenic nucleic acid hybridization probes are widely used for detecting and quantifying nucleic acids. The achieved sensitivity strongly depends on the contrast between a quenched closed form and an unquenched opened form with liberated fluorescence. So far, this contrast was improved by improving the quenching efficiency of the closed form. In this study, we modularly combine these probes with optical antennas used for plasmonic fluorescence enhancement and study the effect of the nanophotonic structure on the fluorescence of the quenched and the opened form. As quenched fluorescent dyes are usually enhanced more by fluorescence enhancement, a detrimental reduction of the contrast between closed and opened form was anticipated. In contrast, we could achieve a surprising increase of the contrast with full additivity of quenching of the dark form and fluorescence enhancement of the bright form. Using single-molecule experiments, we demonstrate that the additivity of the two mechanisms depends on the perfect quenching in the quenched form, and we delineate the rules for new nucleic acid probes for enhanced contrast and absolute brightness. Fluorogenic hybridization probes optimized not only for quenching but also for the brightness of the open form might find application in nucleic acid assays with PCR avoiding detection schemes.

Graphene-based aptamer logic gates and their application to multiplex detection.

PubMed

Wang, Li; Zhu, Jinbo; Han, Lei; Jin, Lihua; Zhu, Chengzhou; Wang, Erkang; Dong, Shaojun

2012-08-28

In this work, a GO/aptamer system was constructed to create multiplex logic operations and enable sensing of multiplex targets. 6-Carboxyfluorescein (FAM)-labeled adenosine triphosphate binding aptamer (ABA) and FAM-labeled thrombin binding aptamer (TBA) were first adsorbed onto graphene oxide (GO) to form a GO/aptamer complex, leading to the quenching of the fluorescence of FAM. We demonstrated that the unique GO/aptamer interaction and the specific aptamer-target recognition in the target/GO/aptamer system were programmable and could be utilized to regulate the fluorescence of FAM via OR and INHIBIT logic gates. The fluorescence changed according to different input combinations, and the integration of OR and INHIBIT logic gates provided an interesting approach for logic sensing applications where multiple target molecules were present. High-throughput fluorescence imagings that enabled the simultaneous processing of many samples by using the combinatorial logic gates were realized. The developed logic gates may find applications in further development of DNA circuits and advanced sensors for the identification of multiple targets in complex chemical environments.

Application of flow cytometry to wine microorganisms.

PubMed

Longin, Cédric; Petitgonnet, Clément; Guilloux-Benatier, Michèle; Rousseaux, Sandrine; Alexandre, Hervé

2017-04-01

Flow cytometry (FCM) is a powerful technique allowing detection and enumeration of microbial populations in food and during food process. Thanks to the fluorescent dyes used and specific probes, FCM provides information about cell physiological state and allows enumeration of a microorganism in a mixed culture. Thus, this technique is increasingly used to quantify pathogen, spoilage microorganisms and microorganisms of interest. Since one decade, FCM applications to the wine field increase greatly to determine population and physiological state of microorganisms performing alcoholic and malolactic fermentations. Wine spoilage microorganisms were also studied. In this review we briefly describe FCM principles. Next, a deep revision concerning enumeration of wine microorganisms by FCM is presented including the fluorescent dyes used and techniques allowing a yeast and bacteria species specific enumeration. Then, the last chapter is dedicated to fluorescent dyes which are used to date in fluorescent microscopy but applicable in FCM. This chapter also describes other interesting "future" techniques which could be applied to study the wine microorganisms. Thus, this review seeks to highlight the main advantages of the flow cytometry applied to wine microbiology. Copyright © 2016 Elsevier Ltd. All rights reserved.

A molecular imprinting-based turn-on Ratiometric fluorescence sensor for highly selective and sensitive detection of 2,4-dichlorophenoxyacetic acid (2,4-D).

PubMed

Wang, Xiaoyan; Yu, Jialuo; Wu, Xiaqing; Fu, Junqing; Kang, Qi; Shen, Dazhong; Li, Jinhua; Chen, Lingxin

2016-07-15

A novel molecular imprinting-based turn-on ratiometric fluorescence sensor was constructed via a facile sol-gel polymerization for detection of 2,4-dichlorophenoxyacetic acid (2,4-D) on the basis of photoinduced electron transfer (PET) by using nitrobenzoxadiazole (NBD) as detection signal source and quantum dots (QDs) as reference signal source. With the presence and increase of 2,4-D, the amine groups on the surface of QDs@SiO2 could bind with 2,4-D and thereby the NBD fluorescence intensities could be significantly enhanced since the PET process was inhibited, while the QDs maintained constant intensities. Accordingly, the ratio of the dual-emission intensities of green NBD and red QDs could be utilized for turn-on fluorescent detection of 2,4-D, along with continuous color changes from orange-red to green readily observed by the naked eye. The as-prepared fluorescence sensor obtained high sensitivity with a low detection limit of 0.14μM within 5min, and distinguished recognition selectivity for 2,4-D over its analogs. Moreover, the sensor was successfully applied to determine 2,4-D in real water samples, and high recoveries at three spiking levels of 2,4-D ranged from 95.0% to 110.1% with precisions below 4.5%. The simple, rapid and reliable visual sensing strategy would not only provide potential applications for high selective ultratrace analysis of complicated matrices, but also greatly enrich the research connotations of molecularly imprinted sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Applications of Nanomaterials Based on Magnetite and Mesoporous Silica on the Selective Detection of Zinc Ion in Live Cell Imaging.

PubMed

Erami, Roghayeh Sadeghi; Ovejero, Karina; Meghdadi, Soraia; Filice, Marco; Amirnasr, Mehdi; Rodríguez-Diéguez, Antonio; De La Orden, María Ulagares; Gómez-Ruiz, Santiago

2018-06-14

Functionalized magnetite nanoparticles (FMNPs) and functionalized mesoporous silica nanoparticles (FMSNs) were synthesized by the conjugation of magnetite and mesoporous silica with the small and fluorogenic benzothiazole ligand, that is, 2(2-hydroxyphenyl)benzothiazole ( hpbtz ). The synthesized fluorescent nanoparticles were characterized by FTIR, XRD, XRF, 13 C CP MAS NMR, BET, and TEM. The photophysical behavior of FMNPs and FMSNs in ethanol was studied using fluorescence spectroscopy. The modification of magnetite and silica scaffolds with the highly fluorescent benzothiazole ligand enabled the nanoparticles to be used as selective and sensitive optical probes for zinc ion detection. Moreover, the presence of hpbtz in FMNPs and FMSNs induced efficient cell viability and zinc ion uptake, with desirable signaling in the normal human kidney epithelial (Hek293) cell line. The significant viability of FMNPs and FMSNs (80% and 92%, respectively) indicates a potential applicability of these nanoparticles as in vitro imaging agents. The calculated limit of detections (LODs) were found to be 2.53 × 10 −6 and 2.55 × 10 −6 M for Fe₃O₄-H@hpbtz and MSN-Et₃N-IPTMS-hpbtz-f1, respectively. FMSNs showed more pronounced zinc signaling relative to FMNPs, as a result of the more efficient penetration into the cells.

A multifunctional Schiff base as a fluorescence sensor for Fe3 + and Zn2 + ions, and a colorimetric sensor for Cu2 + and applications

NASA Astrophysics Data System (ADS)

Tang, Xu; Han, Juan; Wang, Yun; Ni, Liang; Bao, Xu; Wang, Lei; Zhang, Wenli

2017-02-01

Chemosensors play important parts in the selective recognition of ions, which is widely applied in various fields of environment, industry and biological sciences. In this work, a chemosensor for multi-metal ions based on rhodamine B derivative was synthesized, which could selectively recognize various metal ions in different solvent system. The addition of Cu2 + caused the color change from colorless to pink in EtOH/H2O (v/v = 1:1) solvent system, which could be quickly identified by the naked eyes with a detection limit of 8.27 × 10- 8 M. In ethanol solution system, the addition of Fe3 + and Zn2 + caused different fluorescence changes with the detection limit of 2.12 × 10- 7 M and 6.64 × 10- 7 M respectively. The binding ratios are 1:1 (1-Cu2 +), 2:1 (1-Fe3 +) and 1:1 (1-Zn2 +), respectively. Meanwhile, the probe 1 was used to detect the trace metal ions in real water samples. Besides, the probe 1 showed sensitive fluorescence signals for Fe3 + in biological cells. The experimental results further verify the application value of the sensor.

Recent results of synchrotron radiation induced total reflection X-ray fluorescence analysis at HASYLAB, beamline L

NASA Astrophysics Data System (ADS)

Streli, C.; Pepponi, G.; Wobrauschek, P.; Jokubonis, C.; Falkenberg, G.; Záray, G.; Broekaert, J.; Fittschen, U.; Peschel, B.

2006-11-01

At the Hamburger Synchrotronstrahlungslabor (HASYLAB), Beamline L, a vacuum chamber for synchrotron radiation-induced total reflection X-ray fluorescence analysis, is now available which can easily be installed using the adjustment components for microanalysis present at this beamline. The detector is now in the final version of a Vortex silicon drift detector with 50-mm 2 active area from Radiant Detector Technologies. With the Ni/C multilayer monochromator set to 17 keV extrapolated detection limits of 8 fg were obtained using the 50-mm 2 silicon drift detector with 1000 s live time on a sample containing 100 pg of Ni. Various applications are presented, especially of samples which are available in very small amounts: As synchrotron radiation-induced total reflection X-ray fluorescence analysis is much more sensitive than tube-excited total reflection X-ray fluorescence analysis, the sampling time of aerosol samples can be diminished, resulting in a more precise time resolution of atmospheric events. Aerosols, directly sampled on Si reflectors in an impactor were investigated. A further application was the determination of contamination elements in a slurry of high-purity Al 2O 3. No digestion is required; the sample is pipetted and dried before analysis. A comparison with laboratory total reflection X-ray fluorescence analysis showed the higher sensitivity of synchrotron radiation-induced total reflection X-ray fluorescence analysis, more contamination elements could be detected. Using the Si-111 crystal monochromator also available at beamline L, XANES measurements to determine the chemical state were performed. This is only possible with lower sensitivity as the flux transmitted by the crystal monochromator is about a factor of 100 lower than that transmitted by the multilayer monochromator. Preliminary results of X-ray absorption near-edge structure measurements for As in xylem sap from cucumber plants fed with As(III) and As(V) are reported. Detection limits of 170 ng/l of As in xylem sap were achieved.

Part-per-trillion level detection of estradiol by competitive fluorescence immunoassay using DNA/dye conjugate as antibody multiple labels.

PubMed

Zhu, Shengchao; Zhang, Qin; Guo, Liang-Hong

2008-08-22

Fluorescent organic dyes are currently the standard signal-generating labels used in microarray quantification. However, new labeling strategies are needed to meet the demand for high sensitivity in the detection of low-abundance proteins and small molecules. In this report, a long-chain DNA/dye conjugate was used to attach multiple fluorescence labels on antibodies to improve signal intensity and immunoassay sensitivity. Compared with the 30 base-pair (bp) oligonucleotide used in our previous work [Q. Zhang, L.-H. Guo, Bioconjugate Chem. 18 (2007) 1668-1672], conjugation of a 219 bp DNA in solution with a fluorescent DNA binder SYBR Green I resulted in more than sixfold increase in signal intensity, consistent with the increase in bp number. In a direct immunoassay for the detection of goat anti-mouse IgG in a mouse IgG-coated 96-well plate, the long DNA conjugate label also produced higher fluorescence than the short one, accompanied by about 15-fold improvement in the detection limit. To demonstrate its advantage in real applications, the DNA/dye conjugate was employed in the competitive immunoassay of 17beta-estradiol, a clinically and environmentally important analyte. The biotin-terminated DNA was attached to biotinylated anti-estradiol antibody through the biotin/streptavidin/biotin bridge after the immuno-reaction was completed, followed by conjugation with SYBR Green I. The limit of detection for 17beta-estradiol is 1.9 pg mL(-1), which is 200-fold lower than the assay using fluorescein-labeled antibodies. The new multiple labeling strategy uses readily available reagents, and is also compatible with current biochip platform. It has great potential in the sensitive detection of protein and antibody microarrays.

Ratiometric detection of copper ions and alkaline phosphatase activity based on semiconducting polymer dots assembled with rhodamine B hydrazide.

PubMed

Sun, Junyong; Mei, Han; Gao, Feng

2017-05-15

The rational surface functionalization of semiconducting polymer dots (Pdots) has attracted much attention to extend their applications in fabricating chemo/biosensing platform. In this study, a novel ratiometric fluorescent sensing platform using functionalized Pdots as probes for fluorescence signal transmission has been designed for sensing Cu(Ⅱ) and activity of alkaline phosphatase (ALP) with high selectivity and enhanced sensitivity. The highly fluorescent Pdots were firstly prepared with Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)] (PFBT) via nanoprecipitation method, and then assembled with non-fluorescent rhodamine B hydrazide (RB-hy), which shows special binding activity to Cu(Ⅱ), through adsorption process to obtain functionalized nanohybrids, Pdots@RB-hy. As thus, a FRET donors/acceptors pair, in which PFBT Pdots act as energy donors while RB-hy-Cu(II) complexes act as energy acceptors were constructed. On the basis of the varies in fluorescence intensities of donors/acceptors in the presence of different amounts of Cu(II), a ratiometric method for sensing Cu(II) has been proposed. The proposed ratiometric Cu(II) sensor shows a good linear detection range from 0.05 to 5μM with a detection limit of 15nM. Furthermore, using the Pdots@RB-hy-Cu(II) system as signal transducer, a ratiometric sensing for alkaline phosphatase (ALP) activity has also been established with pyrophosphate (PPi) as substrates. The constructed ratiometric sensor of ALP activity displays a linear detection range from 0.005 to 15UL -1 with a detection limit of 0.0018UL -1 . The sensor was further successfully used for ALP activity detection in human serum with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Dual Recognition Strategy for Specific and Sensitive Detection of Bacteria Using Aptamer-Coated Magnetic Beads and Antibiotic-Capped Gold Nanoclusters.

PubMed

Cheng, Dan; Yu, Mengqun; Fu, Fei; Han, Weiye; Li, Gan; Xie, Jianping; Song, Yang; Swihart, Mark T; Song, Erqun

2016-01-05

Food poisoning and infectious diseases caused by pathogenic bacteria such as Staphylococcus aureus (SA) are serious public health concerns. A method of specific, sensitive, and rapid detection of such bacteria is essential and important. This study presents a strategy that combines aptamer and antibiotic-based dual recognition units with magnetic enrichment and fluorescent detection to achieve specific and sensitive quantification of SA in authentic specimens and in the presence of much higher concentrations of other bacteria. Aptamer-coated magnetic beads (Apt-MB) were employed for specific capture of SA. Vancomycin-stabilized fluorescent gold nanoclusters (AuNCs@Van) were prepared by a simple one-step process and used for sensitive quantification of SA in the range of 32-10(8) cfu/mL with the detection limit of 16 cfu/mL via a fluorescence intensity measurement. And using this strategy, about 70 cfu/mL of SA in complex samples (containing 3 × 10(8) cfu/mL of other different contaminated bacteria) could be successfully detected. In comparison to prior studies, the developed strategy here not only simplifies the preparation procedure of the fluorescent probes (AuNCs@Van) to a great extent but also could sensitively quantify SA in the presence of much higher concentrations of other bacteria directly with good accuracy. Moreover, the aptamer and antibiotic used in this strategy are much less expensive and widely available compared to common-used antibodies, making it cost-effective. This general aptamer- and antibiotic-based dual recognition strategy, combined with magnetic enrichment and fluorescent detection of trace bacteria, shows great potential application in monitoring bacterial food contamination and infectious diseases.

Single-molecule spectroscopic methods.

PubMed

Haustein, Elke; Schwille, Petra

2004-10-01

Being praised for the mere fact of enabling the detection of individual fluorophores a dozen years ago, single-molecule techniques nowadays represent standard methods for the elucidation of the structural rearrangements of biologically relevant macromolecules. Single-molecule-sensitive techniques, such as fluorescence correlation spectroscopy, allow real-time access to a multitude of molecular parameters (e.g. diffusion coefficients, concentration and molecular interactions). As a result of various recent advances, this technique shows promise even for intracellular applications. Fluorescence imaging can reveal the spatial localization of fluorophores on nanometer length scales, whereas fluorescence resonance energy transfer supports a wide range of different applications, including real-time monitoring of conformational rearrangements (as in protein folding). Still in their infancy, single-molecule spectroscopic methods thus provide unprecedented insights into basic molecular mechanisms. Copyright 2004 Elsevier Ltd.

Fluorescence fluctuations analysis in nanoapertures: physical concepts and biological applications.

PubMed

Lenne, Pierre-François; Rigneault, Hervé; Marguet, Didier; Wenger, Jérôme

2008-11-01

During the past years, nanophotonics has provided new approaches to study the biological processes below the optical diffraction limit. How single molecules diffuse, bind and assemble can be studied now at the nanometric level, not only in solutions but also in complex and crowded environments such as in live cells. In this context fluorescence fluctuations spectroscopy is a unique tool since it has proven to be easy to use in combination with nanostructures, which are able to confine light in nanometric volumes. We review here recent advances in fluorescence fluctuations' analysis below the optical diffraction limit with a special focus on nanoapertures milled in metallic films. We discuss applications in the field of single-molecule detection, DNA sequencing and membrane organization, and underscore some potential perspectives of this new emerging technology.

Biocompatible Quantum Dots for Biological Applications

PubMed Central

Rosenthal, Sandra J.; Chang, Jerry C.; Kovtun, Oleg; McBride, James R.; Tomlinson, Ian D.

2011-01-01

Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, sizetunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots. PMID:21276935

Graphene-Based Optical Biosensors and Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Zhiwen; He, Shijiang; Pei, Hao

2014-01-13

This chapter focuses on the design, fabrication and application of graphene based optical nanobiosensors. The emerging graphene based optical nanobiosensors demonstrated the promising bioassay and biomedical applications thanking to the unique optical features of graphene. According to the different applications, the graphene can be tailored to form either fluorescent emitter or efficient fluorescence quencher. The exceptional electronic feature of graphene makes it a powerful platform for fabricating the SPR and SERS biosensors. Today the graphene based optical biosensors have been constructed to detect various targets including ions, small biomolecules, DNA/RNA and proteins. This chapter reviews the recent progress in graphene-basedmore » optical biosensors and discusses the opportunities and challenges in this field.« less

Three-photon fluorescence imaging of melanin with a dual-wedge confocal scanning system

NASA Astrophysics Data System (ADS)

Mega, Yair; Kerimo, Joseph; Robinson, Joseph; Vakili, Ali; Johnson, Nicolette; DiMarzio, Charles

2012-03-01

Confocal microscopy can be used as a practical tool in non-invasive applications in medical diagnostics and evaluation. In particular, it is being used for the early detection of skin cancer to identify pathological cellular components and, potentially, replace conventional biopsies. The detection of melanin and its spatial location and distribution plays a crucial role in the detection and evaluation of skin cancer. Our previous work has shown that the visible emission from melanin is strong and can be easily observed with a near-infrared CW laser using low power. This is due to a unique step-wise, (SW) three-photon excitation of melanin. This paper shows that the same SW, 3-photon fluorescence can also be achieved with an inexpensive, continuous-wave laser using a dual-prism scanning system. This demonstrates that the technology could be integrated into a portable confocal microscope for clinical applications. The results presented here are in agreement with images obtained with the larger and more expensive femtosecond laser system used earlier.

Nanometer-Sized Diamond Particle as a Probe for Biolabeling

PubMed Central

Chao, Jui-I.; Perevedentseva, Elena; Chung, Pei-Hua; Liu, Kuang-Kai; Cheng, Chih-Yuan; Chang, Chia-Ching; Cheng, Chia-Liang

2007-01-01

A novel method is proposed using nanometer-sized diamond particles as detection probes for biolabeling. The advantages of nanodiamond's unique properties were demonstrated in its biocompatibility, nontoxicity, easily detected Raman signal, and intrinsic fluorescence from its natural defects without complicated pretreatments. Carboxylated nanodiamond's (cND's) penetration ability, noncytotoxicity, and visualization of cND-cell interactions are demonstrated on A549 human lung epithelial cells. Protein-targeted cell interaction visualization was demonstrated with cND-lysozyme complex interaction with bacteria Escherichia coli. It is shown that the developed biomolecule-cND complex preserves the original functions of the test protein. The easily detected natural fluorescent and Raman intrinsic signals, penetration ability, and low cytotoxicity of cNDs render them promising agents in multiple medical applications. PMID:17513352

Multiple excitation nano-spot generation and confocal detection for far-field microscopy.

PubMed

Mondal, Partha Pratim

2010-03-01

An imaging technique is developed for the controlled generation of multiple excitation nano-spots for far-field microscopy. The system point spread function (PSF) is obtained by interfering two counter-propagating extended depth-of-focus PSF (DoF-PSF), resulting in highly localized multiple excitation spots along the optical axis. The technique permits (1) simultaneous excitation of multiple planes in the specimen; (2) control of the number of spots by confocal detection; and (3) overcoming the point-by-point based excitation. Fluorescence detection from the excitation spots can be efficiently achieved by Z-scanning the detector/pinhole assembly. The technique complements most of the bioimaging techniques and may find potential application in high resolution fluorescence microscopy and nanoscale imaging.

Highly fluorescent carbon quantum dots as nanoprobes for sensitive and selective determination of mercury (II) in surface waters

NASA Astrophysics Data System (ADS)

Hua, Jianhao; Yang, Jian; Zhu, Yan; Zhao, Chunxi; Yang, Yaling

2017-12-01

A novel carbon quantum dots (CQDs) was successfully prepared through one-step green hydrothermal method using polyacrylamide as carbon source. The prepared CQDs were characterized using TEM, XRD, XPS, FT-IR, UV-Vis, and fluorescence spectroscopy. The CQDs was demonstrated as nanoprobes for mercury ion detection, moreover, it demonstrated excitation-dependent and superior stability in acidic and alkaline media. Besides, the probe exhibited a good linearity range (0.25-50 μM) and a low detection limit (13.48 nM). These attractive properties indicated that this novel CQDs can adapt to a variety of complex pH environment, which had extensive prospect and promising application for detection of mercury ions in complex water samples.

[Determination of cyclamate in complex matrix using HPLC after column derivatization with 4-fluoro-7-nitrobenzofurazan].

PubMed

Hauck, M; Köbler, H

1990-01-01

A method for the analysis of cyclamate in complex foodstuffs has been developed. This method is applicable in strongly coloured and protein-rich foodstuffs. The quantitative determination depends on oxidation of cyclamate to cyclohexylamine and derivatisation with 4-fluoro-7-nitrobenzofuran (NBD-F). The derivatives are analysed by HPLC on a C18: reversed-phase column, their minimal stability being 12 h. There are two possible methods of detection: (a) absorbance at 485 nm and (b) fluorescence with excitation at 485 nm and emission at 530 nm. The detection limit of cyclamate is 5 mg/kg foodstuff, with fluorescence detection 0.4 mg/kg. The recoveries are in the range of 88% to 104%.

Multiple excitation nano-spot generation and confocal detection for far-field microscopy

NASA Astrophysics Data System (ADS)

Mondal, Partha Pratim

2010-03-01

An imaging technique is developed for the controlled generation of multiple excitation nano-spots for far-field microscopy. The system point spread function (PSF) is obtained by interfering two counter-propagating extended depth-of-focus PSF (DoF-PSF), resulting in highly localized multiple excitation spots along the optical axis. The technique permits (1) simultaneous excitation of multiple planes in the specimen; (2) control of the number of spots by confocal detection; and (3) overcoming the point-by-point based excitation. Fluorescence detection from the excitation spots can be efficiently achieved by Z-scanning the detector/pinhole assembly. The technique complements most of the bioimaging techniques and may find potential application in high resolution fluorescence microscopy and nanoscale imaging.