Analysis of fluorinated proteins by mass spectrometry.

PubMed

Luck, Linda A

2014-01-01

(19)F NMR has been used as a probe for investigating bioorganic and biological systems for three decades. Recent reviews have touted this nucleus for its unique characteristics that allow probing in vivo biological systems without endogenous signals. (19)F nucleus is exceptionally sensitive to molecular and microenvironmental changes and thus can be exploited to explore structure, dynamics, and changes in a protein or molecule in the cellular environment. We show how mass spectrometry can be used to assess and characterize the incorporation of fluorine into proteins. This methodology can be applied to a number of systems where (19)F NMR is used.

Amplified electrochemiluminescence detection of DNA based on novel quantum dots signal probe by multiple cycling amplification strategy.

PubMed

Tan, Lu; Ge, Junjun; Jiao, Meng; Jie, Guifen; Niu, Shuyan

2018-06-01

In the present work, we designed a unique enzyme-aided multiple amplification strategy for sensitive electrochemiluminescence (ECL) detection of DNA by using the amplified gold nanoparticles (GNPS)-polyamidoamine (PAMAM)-CdSe quantum dots (QDs) signal probe. Firstly, the novel GNPS-PAMAM dendrimers nanostructure with good biocompatibility and electroconductibility contains many amino groups, which can load a large number of CdSe QDs to develop amplified ECL signal probe. Then, the presence of target DNA activated the enzyme-assisted polymerization strand-displacement cycling reaction, and a large number of the hairpin template was opened. Subsequently, the opened stem further interacted with the capture hairpin (HP) DNA on the electrode, and the GNPS-PAMAM-CdSe signal probe hybridized with the exposed stem of the HP to trigger the second new polymerization reaction. Meanwhile, the first cycle was generating abundant DNA triggers which could directly open the template. As a result of the cascade amplification technique, a large number of CdSe QDs signal probe could be assembled on the electrode, generating much amplified ECL signal for sensitive detection of target DNA. Thus, this novel QDs-based amplified ECL strategy holds great promise for DNA detection and can be further exploited for sensing applications in clinical diagnostics. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantum Dot Platform for Single-Cell Molecular Profiling

NASA Astrophysics Data System (ADS)

Zrazhevskiy, Pavel S.

In-depth understanding of the nature of cell physiology and ability to diagnose and control the progression of pathological processes heavily rely on untangling the complexity of intracellular molecular mechanisms and pathways. Therefore, comprehensive molecular profiling of individual cells within the context of their natural tissue or cell culture microenvironment is essential. In principle, this goal can be achieved by tagging each molecular target with a unique reporter probe and detecting its localization with high sensitivity at sub-cellular resolution, primarily via microscopy-based imaging. Yet, neither widely used conventional methods nor more advanced nanoparticle-based techniques have been able to address this task up to date. High multiplexing potential of fluorescent probes is heavily restrained by the inability to uniquely match probes with corresponding molecular targets. This issue is especially relevant for quantum dot probes---while simultaneous spectral imaging of up to 10 different probes is possible, only few can be used concurrently for staining with existing methods. To fully utilize multiplexing potential of quantum dots, it is necessary to design a new staining platform featuring unique assignment of each target to a corresponding quantum dot probe. This dissertation presents two complementary versatile approaches towards achieving comprehensive single-cell molecular profiling and describes engineering of quantum dot probes specifically tailored for each staining method. Analysis of expanded molecular profiles is achieved through augmenting parallel multiplexing capacity with performing several staining cycles on the same specimen in sequential manner. In contrast to other methods utilizing quantum dots or other nanoparticles, which often involve sophisticated probe synthesis, the platform technology presented here takes advantage of simple covalent bioconjugation and non-covalent self-assembly mechanisms for straightforward probe preparation and specimen labeling, requiring no advanced technical skills and being directly applicable for a wide range of molecular profiling studies. Utilization of quantum dot platform for single-cell molecular profiling promises to greatly benefit both biomedical research and clinical diagnostics by providing a tool for addressing phenotypic heterogeneity within large cell populations, opening access to studying low-abundance events often masked or completely erased by batch processing, and elucidating biomarker signatures of diseases critical for accurate diagnostics and targeted therapy.

Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

PubMed

Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

2013-01-02

In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors.

New opportunities in h → 4ℓ

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

Chen, Yi; Harnik, Roni; Vega-Morales, Roberto

2015-09-28

The Higgs decay h → 4ℓ has played an important role in discovering the Higgs and measuring its mass thanks to low background and excellent resolution. Current cuts in this channel have been optimized for Higgs discovery via the dominant tree level ZZ contribution arising from electroweak symmetry breaking. Going forward, one of the primary objectives of this sensitive channel will be to probe other Higgs couplings and search for new physics on top of the tree level ZZ ‘background’. Thanks to interference between these small couplings and the large tree level contribution to ZZ, the h → 4ℓ decaymore » is uniquely capable of probing the magnitude and CP phases of the Higgs couplings to γγ and Zγ as well as, to a lesser extent, ZZ couplings arising from higher dimensional operators. With this in mind we examine how much relaxing current cuts can enhance the sensitivity while also accounting for the dominant non-Higgs continuum \\( q\\overline{q}\\to 4\\ell \\) background. We find the largest enhancement in sensitivity for the hZγ couplings (≳100%) followed by hγγ (≳40%) and less so for the higher dimensional hZZ couplings (a few percent). With these enhancements, we show that couplings of order Standard Model values for hγγ may optimistically be probed by end of Run-II at the LHC while for hZγ perhaps towards the end of a high luminosity LHC. In addition, an appropriately optimized h → 4ℓ analysis can complement direct decays of the Higgs to on-shell γγ and Zγ pairs giving a unique opportunity to directly access the CP properties of these couplings.« less

Double Beta Decays and Neutrinos - Experiments and MOON

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

Ejiri, H.; National Institute of Radiological Sciences, Chiba, 263-8555

2008-01-24

This is a brief review of the present and future experiments of neutrino-less double beta decays (0{nu}{beta}{beta}) and the MOON (Mo Observatory Of Neutrinos) project. High sensitivity 0{nu}{beta}{beta} experiments are unique and realistic probes for studying the Majorana nature of neutrinos and the absolute mass scale as suggested by neutrino oscillation experiments. MOON aims at spectroscopic 0{nu}{beta}{beta} studies with the {nu}-mass sensitivity of 100-30 meV by means of a super ensemble of multilayer modules of scintillator plates and tracking detector planes.

Atom Probe Tomography Studies on the Cu(In,Ga)Se2 Grain Boundaries

PubMed Central

Cojocaru-Mirédin, Oana; Schwarz, Torsten; Choi, Pyuck-Pa; Herbig, Michael; Wuerz, Roland; Raabe, Dierk

2013-01-01

Compared with the existent techniques, atom probe tomography is a unique technique able to chemically characterize the internal interfaces at the nanoscale and in three dimensions. Indeed, APT possesses high sensitivity (in the order of ppm) and high spatial resolution (sub nm). Considerable efforts were done here to prepare an APT tip which contains the desired grain boundary with a known structure. Indeed, site-specific sample preparation using combined focused-ion-beam, electron backscatter diffraction, and transmission electron microscopy is presented in this work. This method allows selected grain boundaries with a known structure and location in Cu(In,Ga)Se2 thin-films to be studied by atom probe tomography. Finally, we discuss the advantages and drawbacks of using the atom probe tomography technique to study the grain boundaries in Cu(In,Ga)Se2 thin-film solar cells. PMID:23629452

Boronate-Based Fluorescent Probes: Imaging Hydrogen Peroxide in Living Systems

PubMed Central

Lin, Vivian S.; Dickinson, Bryan C.; Chang, Christopher J.

2014-01-01

Hydrogen peroxide, a reactive oxygen species with unique chemical properties, is produced endogenously in living systems as a destructive oxidant to ward off pathogens or as a finely tuned second messenger in dynamic cellular signaling pathways. In order to understand the complex roles that hydrogen peroxide can play in biological systems, new tools to monitor hydrogen peroxide in its native settings, with high selectivity and sensitivity, are needed. Knowledge of organic synthetic reactivity provides the foundation for the molecular design of selective, functional hydrogen peroxide probes. A palette of fluorescent and luminescent probes that react chemoselectively with hydrogen peroxide has been developed, utilizing a boronate oxidation trigger. These indicators offer a variety of colors and in cellulo characteristics and have been used to examine hydrogen peroxide in a number of experimental setups, including in vitro fluorometry, confocal fluorescence microscopy, and flow cytometry. In this chapter, we provide an overview of the chemical features of these probes and information on their behavior to help researchers select the optimal probe and application. PMID:23791092

A new probe using hybrid virus-dye nanoparticles for near-infrared fluorescence tomography

NASA Astrophysics Data System (ADS)

Wu, Changfeng; Barnhill, Hannah; Liang, Xiaoping; Wang, Qian; Jiang, Huabei

2005-11-01

A fluorescent probe based on bionanoparticle cowpea mosaic virus has been developed for near-infrared fluorescence tomography. A unique advantage of this probe is that over 30 dye molecules can be loaded onto each viral nanoparticle with an average diameter of 30 nm, making high local dye concentration (∼1.8 mM) possible without significant fluorescence quenching. This ability of high loading of local dye concentration would increase the signal-to-noise ratio considerably, thus sensitivity for detection. We demonstrate successful tomographic fluorescence imaging of a target containing the virus-dye nanoparticles embedded in a tissue-like phantom. Tomographic fluorescence data were obtained through a multi-channel frequency-domain system and the spatial maps of fluorescence quantum yield were recovered with a finite-element-based reconstruction algorithm.

Gamma-ray Burst and Gravitational Wave Counterpart Prospects in the MeV Band with AMEGO

NASA Astrophysics Data System (ADS)

Racusin, Judith; AMEGO Team

2018-01-01

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) Probe mission concept is uniquely suited to address open questions in Gamma-ray Burst (GRB) science including the search for counterparts to gravitational-wave events. AMEGO is a wide field of view instrument (~60 deg radius) with a broad energy range (~200 keV to >10 GeV) and excellent continuum sensitivity. The sensitivity improvement will allow for probes of GRB emission mechanisms and jet composition in ways that have not been accessible with previous instruments. Potential for polarization measurement may also have profound impacts on the understanding of GRB mechanisms. AMEGO will also be an excellent facility for the search for gravitational wave counterparts to binary mergers including at least one neutron star, which are thought to produce short duration GRBs. This poster will describe how the AMEGO will advance these fields.

Specific detection of Mycobacterium sp. genomic DNA using dual labeled gold nanoparticle based electrochemical biosensor.

PubMed

Thiruppathiraja, Chinnasamy; Kamatchiammal, Senthilkumar; Adaikkappan, Periyakaruppan; Santhosh, Devakirubakaran Jayakar; Alagar, Muthukaruppan

2011-10-01

The present study was aimed at the development and evaluation of a DNA electrochemical biosensor for Mycobacterium sp. genomic DNA detection in a clinical specimen using a signal amplifier as dual-labeled AuNPs. The DNA electrochemical biosensors were fabricated using a sandwich detection strategy involving two kinds of DNA probes specific to Mycobacterium sp. genomic DNA. The probes of enzyme ALP and the detector probe both conjugated on the AuNPs and subsequently hybridized with target DNA immobilized in a SAM/ITO electrode followed by characterization with CV, EIS, and DPV analysis using the electroactive species para-nitrophenol generated by ALP through hydrolysis of para-nitrophenol phosphate. The effect of enhanced sensitivity was obtained due to the AuNPs carrying numerous ALPs per hybridization and a detection limit of 1.25 ng/ml genomic DNA was determined under optimized conditions. The dual-labeled AuNP-facilitated electrochemical sensor was also evaluated by clinical sputum samples, showing a higher sensitivity and specificity and the outcome was in agreement with the PCR analysis. In conclusion, the developed electrochemical sensor demonstrated unique sensitivity and specificity for both genomic DNA and sputum samples and can be employed as a regular diagnostics tool for Mycobacterium sp. monitoring in clinical samples. Copyright © 2011 Elsevier Inc. All rights reserved.

Simple and label-free electrochemical impedance Amelogenin gene hybridization biosensing based on reduced graphene oxide.

PubMed

Benvidi, Ali; Rajabzadeh, Nooshin; Mazloum-Ardakani, Mohammad; Heidari, Mohammad Mehdi; Mulchandani, Ashok

2014-08-15

The increasing desire for sensitive, easy, low-cost, and label free methods for the detection of DNA sequences has become a vital matter in biomedical research. For the first time a novel label-free biosensor for sensitive detection of Amelogenin gene (AMEL) using reduced graphene oxide modified glassy carbon electrode (GCE/RGO) has been developed. In this work, detection of DNA hybridization of the target and probe DNA was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The optimum conditions were found for the immobilization of probe on RGO surface and its hybridization with the target DNA. CV and EIS carried out in an aqueous solution containing [Fe(CN)6](3-/4-) redox pair have been used for the biosensor characterization. The biosensor has a wide linear range from 1.0×10(-20) to 1.0×10(-14)M with the lower detection limit of 3.2×10(-21)M. Moreover, the present electrochemical detection offers some unique advantages such as ultrahigh sensitivity, simplicity, and feasibility for apparatus miniaturization in analytical tests. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of RGO, which enhances the probe absorption and promotes direct electron transfer between probe and the electrode surface. This electrochemical DNA sensor could be used for the detection of specific ssDNA sequence in real biological samples. Copyright © 2014 Elsevier B.V. All rights reserved.

The elastase-PK101 structure: Mechanism of an ultrasensitive activity-based probe revealed

DOE PAGES

Lechtenberg, Bernhard C.; Robinson, Howard R.; Kasperkiewicz, Paulina; ...

2015-01-22

Human neutrophil elastase (HNE) plays a central role in neutrophil host defense, but its broad specificity makes HNE a difficult target for both inhibitor and probe development. Recently, we identified the unnatural amino acid containing activity-based probe PK101, which exhibits astounding sensitivity and selectivity for HNE, yet completely lacks mechanistic explanation for its unique characteristics. Here, we present the crystal structure of the HNE-PK101 complex which not only reveals the basis for PK101 ultrasensitivity but also uncovers so far unrecognized HNE features. Strikingly, the Nle( O-Bzl) function in the P4 position of PK101 reveals and leverages an “exo-pocket” on HNEmore » as a critical factor for selectivity. Furthermore, the PK101 P3 position harbors a methionine dioxide function, which mimics a post-translationally oxidized methionine residue and forms a critical hydrogen bond to the backbone amide of Gly219 of HNE. Gly219 resides in a Gly–Gly motif that is unique to HNE, yet compulsory for this interaction. Consequently, this feature enables HNE to accommodate substrates that have undergone methionine oxidation, which constitutes a hallmark post-translational modification of neutrophil signaling.« less

Fiber sensors for molecular detection

NASA Astrophysics Data System (ADS)

Gu, Claire; Yang, Xuan; Zhang, Jin; Newhouse, Rebecca; Cao, Liangcai

2010-11-01

The demand on sensors for detecting chemical and biological agents is greater than ever before, including medical, environmental, food safety, military, and security applications. At present, most detection or sensing techniques tend to be either non-molecular specific, bulky, expensive, relatively inaccurate, or unable to provide real time data. Clearly, alternative sensing technologies are urgently needed. Recently, we have been working to develop a compact fiber optic surface enhanced Raman scattering (SERS) sensor system that integrates various novel ideas to achieve compactness, high sensitivity and consistency, molecular specificity, and automatic preliminary identification capabilities. The unique sensor architecture is expected to bring SERS sensors to practical applications due to a combination of 1) novel SERS substrates that provide the high sensitivity and consistency, molecular specificity, and applicability to a wide range of compounds; 2) a unique hollow core optical fiber probe with double SERS substrate structure that provides the compactness, reliability, low cost, and ease of sampling; and 3) an innovative matched spectral filter set that provides automatic preliminary molecule identification. In this paper, we will review the principle of operation and some of the important milestones of fiber SERS sensor development with emphasis on our recent work to integrate photonic crystal fiber SERS probes with a portable Raman spectrometer and to demonstrate a matched spectral filter for molecule identification.

Construction of a ratiometric fluorescent probe with an extremely large emission shift for imaging hypochlorite in living cells

NASA Astrophysics Data System (ADS)

Song, Xuezhen; Dong, Baoli; Kong, Xiuqi; Wang, Chao; Zhang, Nan; Lin, Weiying

2018-01-01

Hypochlorite is one of the important reactive oxygen species (ROS) and plays critical roles in many biologically vital processes. Herein, we present a unique ratiometric fluorescent probe (CBP) with an extremely large emission shift for detecting hypochlorite in living cells. Utilizing positively charged α,β-unsaturated carbonyl group as the reaction site, the probe CBP itself exhibited near-infrared (NIR) fluorescence at 662 nm, and can display strong blue fluorescence at 456 nm when responded to hypochlorite. Notably, the extremely large emission shift of 206 nm could enable the precise measurement of the fluorescence peak intensities and ratios. CBP showed high sensitivity, excellent selectivity, desirable performance at physiological pH, and low cytotoxicity. The bioimaging experiments demonstrate the biological application of CBP for the ratiometric imaging of hypochlorite in living cells.

In situ X-ray probing reveals fingerprints of surface platinum oxide.

PubMed

Friebel, Daniel; Miller, Daniel J; O'Grady, Christopher P; Anniyev, Toyli; Bargar, John; Bergmann, Uwe; Ogasawara, Hirohito; Wikfeldt, Kjartan Thor; Pettersson, Lars G M; Nilsson, Anders

2011-01-07

In situ X-ray absorption spectroscopy (XAS) at the Pt L(3) edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard X-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF code and complementary extended X-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.

Time-resolved delayed luminescence image microscopy using an europium ion chelate complex.

PubMed Central

Marriott, G.; Heidecker, M.; Diamandis, E. P.; Yan-Marriott, Y.

1994-01-01

Improvements and extended applications of time-resolved delayed luminescence imaging microscopy (TR-DLIM) in cell biology are described. The emission properties of europium ion complexed to a fluorescent chelating group capable of labeling proteins are exploited to provide high contrast images of biotin labeled ligands through detection of the delayed emission. The streptavidin-based macromolecular complex (SBMC) employs streptavidin cross-linked to thyroglobulin multiply labeled with the europium-fluorescent chelate. The fluorescent chelate is efficiently excited with 340-nm light, after which it sensitizes europium ion emission at 612 nm hundreds of microseconds later. The SBMC complex has a high quantum yield orders of magnitude higher than that of eosin, a commonly used delayed luminescent probe, and can be readily seen by the naked eye, even in specimens double-labeled with prompt fluorescent probes. Unlike triplet-state phosphorescent probes, sensitized europium ion emission is insensitive to photobleaching and quenching by molecular oxygen; these properties have been exploited to obtain delayed luminescence images of living cells in aerated medium thus complementing imaging studies using prompt fluorescent probes. Since TR-DLIM has the unique property of rejecting enormous signals that originate from scattered light, autofluorescence, and prompt fluorescence it has been possible to resolve double emission images of living amoeba cells containing an intensely stained lucifer yellow in pinocytosed vesicles and membrane surface-bound SBMC-labeled biotinylated concanavalin A. Images of fixed cells represented in terms of the time decay of the sensitized emission show the lifetime of the europium ion emission is sensitive to the environment in which it is found. Through the coupling of SBMC to streptavidin,a plethora of biotin-based tracer molecules are available for immunocytochemical studies. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 PMID:7811952

A Specific Nucleophilic Ring-Opening Reaction of Aziridines as a Unique Platform for the Construction of Hydrogen Polysulfides Sensors

DOE PAGES

Chen, Wei; Rosser, Ethan W.; Zhang, Di; ...

2015-05-11

Hydrogen polysulfides (H 2S n, n>1) have been recently suggested to be the actual signalling molecules that involved in sulfur-related redox biology. However the exact mechanisms of H 2S n are still poorly understood and a major hurdle in this field is the lack of reliable and convenient methods for H 2S n detection. In this work we report a unique ring-opening reaction of N-sulfonylaziridine by Na 2S 2 under mild conditions. Based on this reaction a novel H 2S n-specific fluorescent probe (AP) was developed. The probe showed high sensitivity and selectivity for H 2S n. Notably, the fluorescentmore » turn-on product, i.e. compound 1, exhibited excellent two-photon photophysical properties and a large Stokes shift. Moreover, the high solid state luminescent efficiency of compound 1 makes it a potential candidate for organic emitters and solid-state lighting devices.« less

Smart Materials Based on DNA Aptamers: Taking Aptasensing to the Next Level

PubMed Central

Mastronardi, Emily; Foster, Amanda; Zhang, Xueru; DeRosa, Maria C.

2014-01-01

“Smart” materials are an emerging category of multifunctional materials with physical or chemical properties that can be controllably altered in response to an external stimulus. By combining the standard properties of the advanced material with the unique ability to recognize and adapt in response to a change in their environment, these materials are finding applications in areas such as sensing and drug delivery. While the majority of these materials are responsive to physical or chemical changes, a particularly exciting area of research seeks to develop smart materials that are sensitive to specific molecular or biomolecular stimuli. These systems require the integration of a molecular recognition probe specific to the target molecule of interest. The ease of synthesis and labeling, low cost, and stability of DNA aptamers make them uniquely suited to effectively serve as molecular recognition probes in novel smart material systems. This review will highlight current work in the area of aptamer-based smart materials and prospects for their future applications. PMID:24553083

CEM-designer: design of custom expression microarrays in the post-ENCODE Era.

PubMed

Arnold, Christian; Externbrink, Fabian; Hackermüller, Jörg; Reiche, Kristin

2014-11-10

Microarrays are widely used in gene expression studies, and custom expression microarrays are popular to monitor expression changes of a customer-defined set of genes. However, the complexity of transcriptomes uncovered recently make custom expression microarray design a non-trivial task. Pervasive transcription and alternative processing of transcripts generate a wealth of interweaved transcripts that requires well-considered probe design strategies and is largely neglected in existing approaches. We developed the web server CEM-Designer that facilitates microarray platform independent design of custom expression microarrays for complex transcriptomes. CEM-Designer covers (i) the collection and generation of a set of unique target sequences from different sources and (ii) the selection of a set of sensitive and specific probes that optimally represents the target sequences. Probe design itself is left to third party software to ensure that probes meet provider-specific constraints. CEM-Designer is available at http://designpipeline.bioinf.uni-leipzig.de. Copyright © 2014 Elsevier B.V. All rights reserved.

Genotyping of Mycobacterium tuberculosis with additional markers enhances accuracy in epidemiological studies.

PubMed Central

Warren, R; Richardson, M; Sampson, S; Hauman, J H; Beyers, N; Donald, P R; van Helden, P D

1996-01-01

Two highly polymorphic Mycobacterium tuberculosis genomic domains, characterized by hybridization to the oligonucleotide (GTG)5, were identified as potential DNA fingerprinting probes. These domains were cloned [pMTB484(1) and pMTB484(2K4), respectively] and shown to be useful for genotype analysis by Southern blotting. These probes were used to genotype geographically linked strains of M. tuberculosis previously shown to have identical IS6110 fingerprints. Subsequent DNA fingerprints generated with MTB484(1) and MTB484(2K4) showed a high degree of polymorphism, allowing subclassification of IS6110-defined clusters into composites of smaller clusters and unique strains. Correlation of the molecular data with patient interviews and clinical records confirmed the sensitivity of these probes, as contacts were established only within subclusters. These findings demonstrate the requirement for multiple probes to accurately classify M. tuberculosis strains, even those with high copy numbers of IS6110. The enhanced accuracy of strain typing should, in turn, further our understanding of the epidemiology of tuberculosis. PMID:8862588

Specific Detection of Clavibacter michiganensis subsp. sepedonicus by Amplification of Three Unique DNA Sequences Isolated by Subtraction Hybridization.

PubMed

Mills, D; Russell, B W; Hanus, J W

1997-08-01

ABSTRACT Three single-copy, unique DNA fragments, designated Cms50, Cms72, and Cms85, were isolated from strain CS3 of Clavibacter michiganensis subsp. sepedonicus by subtraction hybridization using driver DNA from C. michiganensis subsp. insidiosus, C. michiganensis subsp. michiganensis, and Rhodococcus facians. Radio-labeled probes made of these fragments and used in Southern blot analysis revealed each to be absolutely specific to all North American C. michiganensis subsp. sepedonicus strains tested, including plasmidless and nonmucoid strains. The probes have no homology with genomic DNA from related C. michiganensis subspecies insidiosus, michiganensis, and tessellarius, nor with DNA from 11 additional bacterial species and three unidentified strains, some of which have been previously reported to display cross-reactivity with C. michiganensis subsp. sepedonicus-specific antisera. The three fragments shared no homology, and they appeared to be separated from each other by at least 20 kbp in the CS3 genome. Internal primer sets permitted amplification of each fragment by the polymerase chain reaction (PCR) only from C. michiganensis subsp. sepedonicus DNA. In a PCR-based sensitivity assay using a primer set that amplifies Cms85, the lowest level of detection of C. michiganensis subsp. sepedonicus was 100 CFU per milliliter when cells were added to potato core fluid. Erroneous results that may arise from PCR artifacts and mutational events are, therefore, minimized by the redundancy of the primer sets, and the products should be verifiable with unique capture probes in sequence-based detection systems.

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

Gann, Gabriel D. Orebi

Solar neutrinos offer a unique opportunity to study the interaction of neutrinos with matter, a sensitive search for potential new physics effects, and a probe of solar structure and solar system formation. This paper describes the broad physics program addressed by solar neutrino studies, presents the current suite of experiments programs, and describes several potential future detectors that could address the open questions in this field. This paper is a summary of a talk presented at the Neutrino 2014 conference in Boston.

Terbium(III)/gold nanocluster conjugates: the development of a novel ratiometric fluorescent probe for mercury(II) and a paper-based visual sensor.

PubMed

Qi, Yan-Xia; Zhang, Min; Zhu, Anwei; Shi, Guoyue

2015-08-21

In this work, a novel ratiometric fluorescent probe was developed for rapid, highly accurate, sensitive and selective detection of mercury(II) (Hg(2+)) based on terbium(III)/gold nanocluster conjugates (Tb(3+)/BSA-AuNCs), in which bovine serum albumin capped gold nanoclusters (BSA-AuNCs) acted as the signal indicator and terbium(III) (Tb(3+)) was used as the build-in reference. Our proposed ratiometric fluorescent probe exhibited unique specificity toward Hg(2+) against other common environmentally and biologically important metal ions, and had high accuracy and sensitivity with a low detection limit of 1 nM. In addition, our proposed probe was effectively employed to detect Hg(2+) in the biological samples from the artificial Hg(2+)-infected rats. More significantly, an appealing paper-based visual sensor for Hg(2+) was designed by using filter paper embedded with Tb(3+)/BSA-AuNC conjugates, and we have further demonstrated its feasibility for facile fluorescent sensing of Hg(2+) in a visual format, in which only a handheld UV lamp is used. In the presence of Hg(2+), the paper-based visual sensor, illuminated by a handheld UV lamp, would undergo a distinct fluorescence color change from red to green, which can be readily observed with naked eyes even in trace Hg(2+) concentrations. The Tb(3+)/BSA-AuNC-derived paper-based visual sensor is cost-effective, portable, disposable and easy-to-use. This work unveiled a facile approach for accurate, sensitive and selective measuring of Hg(2+) with self-calibration.

The effect of panic disorder versus anxiety sensitivity on event-related potentials during anticipation of threat.

PubMed

Stevens, Elizabeth S; Weinberg, Anna; Nelson, Brady D; Meissel, Emily E E; Shankman, Stewart A

2018-03-01

Attention-related abnormalities are key components of the abnormal defensive responding observed in panic disorder (PD). Although behavioral studies have found aberrant attentional biases towards threat in PD, psychophysiological studies have been mixed. Predictability of threat, an important feature of threat processing, may have contributed to these mixed findings. Additionally, anxiety sensitivity, a dimensional trait associated with PD, may yield stronger associations with cognitive processes than categorical diagnoses of PD. In this study, 171 participants with PD and/or depression and healthy controls completed a task that differentiated anticipation of predictable vs. unpredictable shocks, while startle eyeblink and event-related potentials (ERPs [N100, P300]) were recorded. In all participants, relative to the control condition, probe N100 was enhanced to both predictable and unpredictable threat, whereas P300 suppression was unique to predictable threat. Probe N100, but not P300, was associated with startle eyeblink during both threatening conditions, and was strongest for unpredictable threat. PD was not associated with ERPs, but anxiety sensitivity (physical concerns) was positively associated with probe N100 (indicating reduced responding) in the unpredictable condition independent of PD diagnosis. Vulnerability to panic-related psychopathology may be characterized by aberrant early processing of threat, which may be especially evident during anticipation of unpredictable threats. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long-stem shaped multifunctional molecular beacon for highly sensitive nucleic acids determination via intramolecular and intermolecular interactions based strand displacement amplification.

PubMed

Xu, Jianguo; Zheng, Tingting; Le, Jingqing; Jia, Lee

2017-11-20

Occurrence and application of oligonucleotide probes have promoted great progress in the biochemical analysis field due to their unique biological and chemical properties. In this work, a long-stem shaped multifunctional molecular beacon (LS-MMB) that is responsive to a cancer-related gene, p53, is well-prepared. By designing the probe with long-paired bases at its two ends and short-paired bases between the middle region and the 3' end, the LS-MMB is intelligently endowed with the ability to recognize the target analyte, serve as the polymerization primer/template, and signal the hybridization event synchronously, which is distinctly advantageous over the traditional molecular beacons (MBs). Moreover, it is excitingly found that the LS-MMB can be employed to exert intramolecular and intermolecular interactions for strand displacement amplification (SDA) without the involvement of any assistant probes; this therapy results in a really easy and rapid sensing system that provides an extremely low background noise and high target output signal. In this case, an excellent sensitivity and specificity to detect target gene down to picomolar level and resolution to even one nucleotide variation are achieved, respectively. In addition, the application potential for real genomic DNA analysis is realized. We envision that the probe of LS-MMB can act as a universal platform for biosensing and biomedical research.

Corrosion Detection in Airframes Using a New Flux-Focusing Eddy Current Probe

NASA Technical Reports Server (NTRS)

Fulton, James P.; Wincheski, Buzz; Nath, Shridhar; Namkung, Min

1994-01-01

A new flux-focusing eddy current probe was recently developed at NASA Langley Research Center. The new probe is similar in design to a reflection type eddy current probe, but is unique in that it does not require the use of an impedance bridge for balancing. The device monitors the RMS output voltage of a pickup coil and, as a result, is easier to operate and interpret than traditional eddy current instruments. The unique design feature of the probe is a ferromagnetic cylinder, typically 1020 steel, which separates a concentrically positioned drive and pickup coil. The increased permeability of the steel causes the magnetic flux produced by the drive coil to be focused in a ring around the pickup coil. At high frequencies the eddy currents induced in both the sample and the cylinder allow little or no flux to link with the pickup coil. This results in a self-nulling condition which has been shown to be useful for the unambiguous detection of cracks in conducting materials. As the frequency is lowered the flux produced by the drive coil begins to link with the pickup coil causing an output which, among other things, is proportional to the thickness of the test specimen. This enables highly accurate measurements of the thickness of conducting materials and helps to facilitate the monitoring of thickness variations in a conducting structure such as an aircraft fuselage. Under ideal laboratory conditions the probe can sense thickness changes on the order of 1% as illustrated. However, this is highly dependent upon the thickness, and the geometric complexity of the sample being tested and for practical problems the sensitivity is usually much less. In this presentation we highlight some of the advantages and limitations in using the probe to inspect aircraft panels for corrosion and other types of material nonuniformities. In particular, we present preliminary results which illustrate the probes capabilities for detecting first and second layer corrosion in aircraft panels which may contain air gaps between the layers. Since the probe utilized eddy currents its corrosion detection capabilities are similar to convectional eddy current techniques, but the new probe is much easier to use.

Application of a unique server-based oligonucleotide probe selection tool toward a novel biosensor for the detection of Streptococcus pyogenes.

PubMed

Nugen, Sam R; Leonard, Barbara; Baeumner, Antje J

2007-05-15

We developed a software program for the rapid selection of detection probes to be used in nucleic acid-based assays. In comparison to commercially available software packages, our program allows the addition of oligotags as required by nucleic acid sequence-based amplification (NASBA) as well as automatic BLAST searches for all probe/primer pairs. We then demonstrated the usefulness of the program by designing a novel lateral flow biosensor for Streptococcus pyogenes that does not rely on amplification methods such as the polymerase chain reaction (PCR) or NASBA to obtain low limits of detection, but instead uses multiple reporter and capture probes per target sequence and an instantaneous amplification via dye-encapsulating liposomes. These assays will decrease the detection time to just a 20 min hybridization reaction and avoid costly enzymatic gene amplification reactions. The lateral flow assay was developed quantifying the 16S rRNA from S. pyogenes by designing reporter and capture probes that specifically hybridize with the RNA and form a sandwich. DNA reporter probes were tagged with dye-encapsulating liposomes, biotinylated DNA oligonucleotides were used as capture probes. From the initial number of capture and reporter probes chosen, a combination of two capture and three reporter probes were found to provide optimal signal generation and significant enhancement over single capture/reporter probe combinations. The selectivity of the biosensor was proven by analyzing organisms closely related to S. pyogenes, such as other Streptococcus and Enterococcus species. All probes had been selected by the software program within minutes and no iterative optimization and re-design of the oligonucleotides was required which enabled a very rapid biosensor prototyping. While the sensitivity obtained with the biosensor was only 135 ng, future experiments will decrease this significantly by the addition of more reporter and capture probes for either the same rRNA or a different nucleic acid target molecule. This will lead to the possibility of detecting S. pyogenes with a rugged assay that does not require a cell culturing or gene amplification step and will therefore enable rapid, specific and sensitive onsite testing.

Edesign: Primer and Enhanced Internal Probe Design Tool for Quantitative PCR Experiments and Genotyping Assays.

PubMed

Kimura, Yasumasa; Soma, Takahiro; Kasahara, Naoko; Delobel, Diane; Hanami, Takeshi; Tanaka, Yuki; de Hoon, Michiel J L; Hayashizaki, Yoshihide; Usui, Kengo; Harbers, Matthias

2016-01-01

Analytical PCR experiments preferably use internal probes for monitoring the amplification reaction and specific detection of the amplicon. Such internal probes have to be designed in close context with the amplification primers, and may require additional considerations for the detection of genetic variations. Here we describe Edesign, a new online and stand-alone tool for designing sets of PCR primers together with an internal probe for conducting quantitative real-time PCR (qPCR) and genotypic experiments. Edesign can be used for selecting standard DNA oligonucleotides like for instance TaqMan probes, but has been further extended with new functions and enhanced design features for Eprobes. Eprobes, with their single thiazole orange-labelled nucleotide, allow for highly sensitive genotypic assays because of their higher DNA binding affinity as compared to standard DNA oligonucleotides. Using new thermodynamic parameters, Edesign considers unique features of Eprobes during primer and probe design for establishing qPCR experiments and genotyping by melting curve analysis. Additional functions in Edesign allow probe design for effective discrimination between wild-type sequences and genetic variations either using standard DNA oligonucleotides or Eprobes. Edesign can be freely accessed online at http://www.dnaform.com/edesign2/, and the source code is available for download.

Edesign: Primer and Enhanced Internal Probe Design Tool for Quantitative PCR Experiments and Genotyping Assays

PubMed Central

Kasahara, Naoko; Delobel, Diane; Hanami, Takeshi; Tanaka, Yuki; de Hoon, Michiel J. L.; Hayashizaki, Yoshihide; Usui, Kengo; Harbers, Matthias

2016-01-01

Analytical PCR experiments preferably use internal probes for monitoring the amplification reaction and specific detection of the amplicon. Such internal probes have to be designed in close context with the amplification primers, and may require additional considerations for the detection of genetic variations. Here we describe Edesign, a new online and stand-alone tool for designing sets of PCR primers together with an internal probe for conducting quantitative real-time PCR (qPCR) and genotypic experiments. Edesign can be used for selecting standard DNA oligonucleotides like for instance TaqMan probes, but has been further extended with new functions and enhanced design features for Eprobes. Eprobes, with their single thiazole orange-labelled nucleotide, allow for highly sensitive genotypic assays because of their higher DNA binding affinity as compared to standard DNA oligonucleotides. Using new thermodynamic parameters, Edesign considers unique features of Eprobes during primer and probe design for establishing qPCR experiments and genotyping by melting curve analysis. Additional functions in Edesign allow probe design for effective discrimination between wild-type sequences and genetic variations either using standard DNA oligonucleotides or Eprobes. Edesign can be freely accessed online at http://www.dnaform.com/edesign2/, and the source code is available for download. PMID:26863543

Thin film absorption characterization by focus error thermal lensing

NASA Astrophysics Data System (ADS)

Domené, Esteban A.; Schiltz, Drew; Patel, Dinesh; Day, Travis; Jankowska, E.; Martínez, Oscar E.; Rocca, Jorge J.; Menoni, Carmen S.

2017-12-01

A simple, highly sensitive technique for measuring absorbed power in thin film dielectrics based on thermal lensing is demonstrated. Absorption of an amplitude modulated or pulsed incident pump beam by a thin film acts as a heat source that induces thermal lensing in the substrate. A second continuous wave collimated probe beam defocuses after passing through the sample. Determination of absorption is achieved by quantifying the change of the probe beam profile at the focal plane using a four-quadrant detector and cylindrical lenses to generate a focus error signal. This signal is inherently insensitive to deflection, which removes noise contribution from point beam stability. A linear dependence of the focus error signal on the absorbed power is shown for a dynamic range of over 105. This technique was used to measure absorption loss in dielectric thin films deposited on fused silica substrates. In pulsed configuration, a single shot sensitivity of about 20 ppm is demonstrated, providing a unique technique for the characterization of moving targets as found in thin film growth instrumentation.

Thiophene-based rhodamine as selectivef luorescence probe for Fe(III) and Al(III) in living cells.

PubMed

Wang, Kun-Peng; Chen, Ju-Peng; Zhang, Si-Jie; Lei, Yang; Zhong, Hua; Chen, Shaojin; Zhou, Xin-Hong; Hu, Zhi-Qiang

2017-09-01

The thiophene-modified rhodamine 6G (GYJ) has been synthesized as a novel chemosensor. The sensor has sufficiently high selectivity and sensitivity for the detection of Fe 3+ and Al 3+ ions (M 3+ ) by fluorescence and ultraviolet spectroscopy with a strong ability for anti-interference performance. The binding ratio of M 3+ -GYJ complex was determined to be 2:1 according to the Job's plot. The binding constants for Fe 3+ and Al 3+ were calculated to be 3.91 × 10 8 and 5.26 × 10 8  M -2 , respectively. All these unique features made it particularly favorable for cellular imaging applications. The obvious fluorescence microscopy experiments demonstrated that the probes could contribute to the detection of Fe 3+ and Al 3+ in related cells and biological organs with satisfying resolution. Graphical abstract GYJ has high selectivity and sensitivity for the detection of Fe(III) and Al(III) with the binding ratio of 2:1.

Right-handed neutrinos and T-violating, P-conserving interactions

NASA Astrophysics Data System (ADS)

El-Menoufi, Basem Kamal; Ramsey-Musolf, Michael J.; Seng, Chien-Yeah

2017-02-01

We show that experimental probes of the P-conserving, T-violating triple correlation in polarized neutron or nuclear β-decay provide a unique probe of possible T-violation at the TeV scale in the presence of right-handed neutrinos. In contrast to other possible sources of semileptonic T-violation involving only left-handed neutrinos, those involving right-handed neutrinos are relatively unconstrained by present limits on the permanent electric dipole moments of the electron, neutral atoms, and the neutron. On the other hand, LHC results for pp → e + missing transverse energy imply that an order of magnitude of improvement in D-coefficient sensitivity would be needed for discovery. Finally, we discuss the interplay with the scale of neutrino mass and naturalness considerations.

Quantum Sensing Beyond the Shot-Noise Limit with Plasmonic Sensors

NASA Astrophysics Data System (ADS)

Dowran, Mohammadjavad; Kumar, Ashok; Lawrie, Benjamin; Pooser, Raphael; Marino, Alberto

2017-04-01

The use of quantum resources offers the possibility of enhancing the sensitivity of a device beyond the shot noise limit and promises to revolutionize the field of metrology through the development of quantum enhanced sensors. In particular, plasmonic sensors, which are widely used in bio-chemical sensing applications, provide a unique opportunity to bring such an enhancement to real-life devices. Resonance plasmonic sensors respond to changes in refractive index through a shift of their characteristic transmission spectrum. We show that the use of quantum squeezed states to probe plasmonic sensors can enhance their sensitivity by lowering the noise floor and allowing the detection of smaller changes in refractive index. In our experiment, we use one of the beams of a two-mode squeezed state generated via four-wave-mixing in Rb atoms to probe the sensor. A squeezing level of 4 dB is obtained after transduction through the plasmonic sensor, which consists of a triangular nano-hole array in a thin silver film and exhibits a sensitivity of the order of 10-10 RIU /√{ Hz} . The use of quantum states leads to 40 % enhancement in the sensitivity of the plasmonic sensor with respect to the shot noise limit. Work supported by the W.M. Keck Foundation.

Improving colorimetric assays through protein enzyme-assisted gold nanoparticle amplification.

PubMed

Xie, Xiaoji; Xu, Wei; Liu, Xiaogang

2012-09-18

The discovery of the DNA-mediated assembly of gold nanoparticles was a great moment in the history of science; this understanding and chemical control enabled the rational design of functional nanomaterials as novel probes in biodetection. In contrast with conventional probes such as organic dyes, gold nanoparticles exhibit high photostability and unique size-dependent optical properties. Because of their high extinction coefficients and strong distance dependent optical properties, these nanoparticles have emerged over the past decade as a promising platform for rapid, highly sensitive colorimetric assays that allow for the visual detection of low concentrations of metal ions, small molecules, and biomacromolecules. These discoveries have deepened our knowledge of biological phenomena and facilitated the development of many new diagnostic and therapeutic tools. Despite these many advances and continued research efforts, current nanoparticle-based colorimetric detection systems still suffer from several drawbacks, such as limited sensitivity and selectivity. This Account describes the recent development of colorimetric assays based on protein enzyme-assisted gold nanoparticle amplification. The benefits of such detection systems include significantly improved detection sensitivity and selectivity. First, we discuss the general design of enzyme-modified nanoparticle systems in colorimetric assays. We show that a quantitative understanding of the unique properties of different enzymes is paramount for effective biological assays. We then examine the assays for nucleic acid detection based on different types of enzymes, including endonucleases, ligases, and polymerases. For each of these assays, we identify the underlying principles that contribute to the enhanced detection capability of nanoparticle systems and illustrate them with selected examples. Furthermore, we demonstrate that the combination of gold nanoparticles and specific enzymes can probe enzyme dynamics and function with high specificity, offering substantial advantages in both sensitivity and specificity over conventional detection methods. The screening of nuclease, methyltransferase, protease, and kinase activities can be colorimetrically performed in a straightforward manner. Finally, we discuss examples of colorimetric assays for metal ions and small molecules that constitute important advances toward visual monitoring of enzyme catalytic functions and gene expression. Although these enzyme-assisted assay methods hold great promise for myriad applications in biomedicine and bioimaging, the application of the described techniques in vivo faces formidable challenges. In addition, researchers do not fully understand the interactions of gold nanoparticles with enzyme molecules. This understanding will require the development of new techniques to probe enzyme substrate dynamics at the particle interface with higher spatial resolution and chemical specificity.

Pulsed Polarimetry and magnetic sensing on the Magnetized Shock Experiment (MSX)

NASA Astrophysics Data System (ADS)

Smith, R. J.; Hutchinson, T. M.; Weber, T. E.; Taylor, S. F.; Hsu, S. C.

2014-10-01

MSX is uniquely positioned to generate the conditions for collision-less magnetized supercritical shocks with Alvenic Mach numbers (MA) of the order 10 and higher. Significant operational strides have been made in forming plasmas over wide parameter ranges: (Te + Ti) of 10-200 eV, average neof 5-60×10+21 m-3, speeds up to 150 km/s and fields up to 1T with a highest plasma flow MA of 5 to date. The MSX plasma is unique in regards to large plasma size of 10 cm and average β higher than 0.8 making the FRC and the magnetized shock structure candidates for the application of Pulsed Polarimetry, a polarization sensitive Lidar technique. The shock dynamics are presently being investigated using internal probes, interferometry and imaging. Internal probe results and an assessment of the shock parameters will dictate the use of the UW pulsed polarimeter system in which internal ne, Teand B are to be measured. Recent results will be presented. Supported by DOE Office of Fusion Energy Sciences Funding DE-FOA-0000755.

Immunosensing with Near-Infrared Plasmonic Optical Fiber Gratings.

PubMed

Caucheteur, Christophe; Ribaut, Clotilde; Malachovska, Viera; Wattiez, Ruddy

2017-01-01

Surface Plasmon resonance (SPR) optical fiber biosensors constitute a miniaturized counterpart to the bulky prism configuration and offer remote operation in very small volumes of analyte. They are a cost-effective and relatively straightforward technique to yield in situ (or even possibly in vivo) molecular detection. They are usually obtained from a gold-coated fiber segment for which the core-guided light is brought into contact with the surrounding medium, either by etching (or side-polishing) or by using grating coupling. Recently, SPR generation was achieved in gold-coated tilted fiber Bragg gratings (TFBGs). These sensors probe the surrounding medium with near-infrared narrowband resonances, which enhances both the penetration depth of the evanescent field in the external medium and the wavelength resolution of the interrogation. They constitute the unique configuration able to probe all the fiber cladding modes individually, with high Q-factors. We use these unique spectral features in our work to sense proteins and extra-cellular membrane receptors that are both overexpressed in cancerous tissues. Impressive limit of detection (LOD) and sensitivity are reported, which paves the way for the further use of such immunosensors for cancer diagnosis.

Quantifying Nucleic Acid Ensembles with X-ray Scattering Interferometry.

PubMed

Shi, Xuesong; Bonilla, Steve; Herschlag, Daniel; Harbury, Pehr

2015-01-01

The conformational ensemble of a macromolecule is the complete description of the macromolecule's solution structures and can reveal important aspects of macromolecular folding, recognition, and function. However, most experimental approaches determine an average or predominant structure, or follow transitions between states that each can only be described by an average structure. Ensembles have been extremely difficult to experimentally characterize. We present the unique advantages and capabilities of a new biophysical technique, X-ray scattering interferometry (XSI), for probing and quantifying structural ensembles. XSI measures the interference of scattered waves from two heavy metal probes attached site specifically to a macromolecule. A Fourier transform of the interference pattern gives the fractional abundance of different probe separations directly representing the multiple conformation states populated by the macromolecule. These probe-probe distance distributions can then be used to define the structural ensemble of the macromolecule. XSI provides accurate, calibrated distance in a model-independent fashion with angstrom scale sensitivity in distances. XSI data can be compared in a straightforward manner to atomic coordinates determined experimentally or predicted by molecular dynamics simulations. We describe the conceptual framework for XSI and provide a detailed protocol for carrying out an XSI experiment. © 2015 Elsevier Inc. All rights reserved.

Applications of nanopipettes in bionanotechnology.

PubMed

Ying, Liming

2009-08-01

At present, technical hurdles remain in probing biochemical processes in living cells and organisms at nanometre spatial resolution, millisecond time resolution and with high specificity and single-molecule sensitivity. Owing to its unique shape, size and electrical properties, the nanopipette has been used to obtain high-resolution topographic images of live cells under physiological conditions, and to create nanoscale features by controlled delivery of biomolecules. In the present paper, I discuss recent progress in the development of a family of new methods for nanosensing and nanomanipulation using nanopipettes.

Everything under the Sun: A review of solar neutrinos

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

Gann, Gabriel D. Orebi

2015-07-15

Solar neutrinos offer a unique opportunity to study the interaction of neutrinos with matter, a sensitive search for potential new physics effects, and a probe of solar structure and solar system formation. This paper describes the broad physics program addressed by solar neutrino studies, presents the current suite of experiments programs, and describes several potential future detectors that could address the open questions in this field. This paper is a summary of a talk presented at the Neutrino 2014 conference in Boston.

Anilinomethylrhodamines: pH sensitive probes with tunable photophysical properties by substituent effect.

PubMed

Best, Quinn A; Liu, Chuangjun; van Hoveln, Paul D; McCarroll, Matthew E; Scott, Colleen N

2013-10-18

A series of pH dependent rhodamine analogues possessing an anilino-methyl moiety was developed and shown to exhibit a unique photophysical response to pH. These anilinomethylrhodamines (AnMR) maintain a colorless, nonfluorescent spirocyclic structure at high pH. The spirocyclic structures open in mildly acidic conditions and are weakly fluorescent; however, at very low pH, the fluorescence is greatly enhanced. The equilibrium constants of these processes show a linear response to substituent effects, which was demonstrated by the Hammett equation.

Everything under the sun: A review of solar neutrinos

DOE PAGES

Gann, Gabriel D. Orebi

2015-07-15

Solar neutrinos offer a unique opportunity to study the interaction of neutrinos with matter, a sensitive search for potential new physics effects, and a probe of solar structure and solar system formation. This paper describes the broad physics program addressed by solar neutrino studies, presents the current suite of experiments programs, and describes several potential future detectors that could address the open questions in this field. This paper is a summary of a talk presented at the Neutrino 2014 conference in Boston.

Einstein Inflationary Probe (EIP)

NASA Technical Reports Server (NTRS)

Hinshaw, Gary

2004-01-01

I will discuss plans to develop a concept for the Einstein Inflation Probe: a mission to detect gravity waves from inflation via the unique signature they impart to the cosmic microwave background (CMB) polarization. A sensitive CMB polarization satellite may be the only way to probe physics at the grand-unified theory (GUT) scale, exceeding by 12 orders of magnitude the energies studied at the Large Hadron Collider. A detection of gravity waves would represent a remarkable confirmation of the inflationary paradigm and set the energy scale at which inflation occurred when the universe was a fraction of a second old. Even a strong upper limit to the gravity wave amplitude would be significant, ruling out many common models of inflation, and pointing to inflation occurring at much lower energy, if at all. Measuring gravity waves via the CMB polarization will be challenging. We will undertake a comprehensive study to identify the critical scientific requirements for the mission and their derived instrumental performance requirements. At the core of the study will be an assessment of what is scientifically and experimentally optimal within the scope and purpose of the Einstein Inflation Probe.

A DNA microarray for identification of selected Korean birds based on mitochondrial cytochrome c oxidase I gene sequences.

PubMed

Chung, In-Hyuk; Yoo, Hye Sook; Eah, Jae-Yong; Yoon, Hyun-Kyu; Jung, Jin-Wook; Hwang, Seung Yong; Kim, Chang-Bae

2010-10-01

DNA barcoding with the gene encoding cytochrome c oxidase I (COI) in the mitochondrial genome has been proposed as a standard marker to identify and discover animal species. Some migratory wild birds are suspected of transmitting avian influenza and pose a threat to aircraft safety because of bird strikes. We have previously reported the COI gene sequences of 92 Korean bird species. In the present study, we developed a DNA microarray to identify 17 selected bird species on the basis of nucleotide diversity. We designed and synthesized 19 specific oligonucleotide probes; these probes were arrayed on a silylated glass slide. The length of the probes was 19-24 bps. The COI sequences amplified from the tissues of the selected birds were labeled with a fluorescent probe for microarray hybridization, and unique hybridization patterns were detected for each selected species. These patterns may be considered diagnostic patterns for species identification. This microarray system will provide a sensitive and a high-throughput method for identification of Korean birds.

An ultrasensitive SiO2-encapsulated alloyed CdZnSeS quantum dot-molecular beacon nanobiosensor for norovirus.

PubMed

Adegoke, Oluwasesan; Seo, Min-Woong; Kato, Tatsuya; Kawahito, Shoji; Park, Enoch Y

2016-12-15

Ultrasensitive, rapid and selective diagnostic probes are urgently needed to overcome the limitations of traditional probes for norovirus (NV). Here, we report the detection of NV genogroup II via nucleic acid hybridization technology using a quantum dot (QD)-conjugated molecular beacon (MB) probe. To boost the sensitivity of the MB assay system, an ultrasensitive QD fluorophore with unique optical properties was synthesized, characterized and exploited as a fluorescence signal generator. Alloyed thioglycolic (TGA)-capped CdZnSeS QDs with a high photoluminescence (PL) quantum yield (QY) value of 92% were synthesized, and a modified silanization method was employed to encapsulate the thiol-capped QDs in a silica layer. The resulting highly luminescent alloyed SiO2-coated CdZnSeS QDs had a remarkable PL QY value of 98%. Transmission electron microscopy and dynamic light scattering confirmed the monodispersity of the alloyed nanocrystals, and zeta potential analysis confirmed their colloidal stability. Powder X-ray diffraction and PL lifetime measurements confirmed the surface modification of the QDs. The alloyed TGA-capped and SiO2-coated CdZnSeS QD-conjugated MB bioprobes detected extremely low concentrations of NV RNA. Ultrasensitive detection of low concentrations of NV RNA with a limit of detection (LOD) of 8.2copies/mL in human serum and a LOD of 9.3 copies/mL in buffer was achieved using the SiO2-coated CdZnSeS QD-MB probes, an increase in sensitivity of 3-fold compared with the detection limit for NV RNA using TGA-capped CdZnSeS QD-MBs. The additional merits of our detection system are rapidity, specificity and improved sensitivity over conventional molecular test probes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Probing thyroglobulin in undiluted human serum based on pattern recognition and competitive adsorption of proteins

NASA Astrophysics Data System (ADS)

Wang, Ran; Huang, Shuai; Li, Jing; Chae, Junseok

2014-10-01

Thyroglobulin (Tg) is a sensitive indicator of persistent or recurrent differentiated thyroid cancer of follicular cell origin. Detection of Tg in human serum is challenging as bio-receptors, such as anti-Tg, used in immunoassay have relatively weak binding affinity. We engineer sensing surfaces using the competitive adsorption of proteins, termed the Vroman Effect. Coupled with Surface Plasmon Resonance, the "cross-responsive" interactions of Tg on the engineered surfaces produce uniquely distinguishable multiple signature patterns, which are discriminated using Linear Discriminant Analysis. Tg-spiked samples, down to 2 ng/ml Tg in undiluted human serum, are sensitively and selectively discriminated from the control (undiluted human serum).

Retrieval of complex χ(2) parts for quantitative analysis of sum-frequency generation intensity spectra

PubMed Central

Hofmann, Matthias J.; Koelsch, Patrick

2015-01-01

Vibrational sum-frequency generation (SFG) spectroscopy has become an established technique for in situ surface analysis. While spectral recording procedures and hardware have been optimized, unique data analysis routines have yet to be established. The SFG intensity is related to probing geometries and properties of the system under investigation such as the absolute square of the second-order susceptibility χ(2)2. A conventional SFG intensity measurement does not grant access to the complex parts of χ(2) unless further assumptions have been made. It is therefore difficult, sometimes impossible, to establish a unique fitting solution for SFG intensity spectra. Recently, interferometric phase-sensitive SFG or heterodyne detection methods have been introduced to measure real and imaginary parts of χ(2) experimentally. Here, we demonstrate that iterative phase-matching between complex spectra retrieved from maximum entropy method analysis and fitting of intensity SFG spectra (iMEMfit) leads to a unique solution for the complex parts of χ(2) and enables quantitative analysis of SFG intensity spectra. A comparison between complex parts retrieved by iMEMfit applied to intensity spectra and phase sensitive experimental data shows excellent agreement between the two methods. PMID:26450297

Minimum probe length for unique identification of all open reading frames in a microbial genome

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

Sokhansanj, B A; Ng, J; Fitch, J P

2000-03-05

In this paper, we determine the minimum hybridization probe length to uniquely identify at least 95% of the open reading frame (ORF) in an organism. We analyze the whole genome sequences of 17 species, 11 bacteria, 4 archaea, and 2 eukaryotes. We also present a mathematical model for minimum probe length based on assuming that all ORFs are random, of constant length, and contain an equal distribution of bases. The model accurately predicts the minimum probe length for all species, but it incorrectly predicts that all ORFs may be uniquely identified. However, a probe length of just 9 bases ismore » adequate to identify over 95% of the ORFs for all 15 prokaryotic species we studied. Using a minimum probe length, while accepting that some ORFs may not be identified and that data will be lost due to hybridization error, may result in significant savings in microarray and oligonucleotide probe design.« less

Data processing in neutron protein crystallography using positron-sensitive detectors

NASA Astrophysics Data System (ADS)

Schoenborn, B. P.

Neutrons provide a unique probe for localizing hydrogen atoms and for distinguishing hydrogen from deuterons. Hydrogen atoms largely determine the three dimensional structure of proteins and are responsible for many catalytic reactions. The study of hydrogen bonding and hydrogen exchange will therefore give insight into reaction mechanisms and conformational fluctuations. In addition, neutrons provide the ability to distinguish N from C and O and to allow correct orientation of groups such as histidine and glutamine. To take advantage of these unique features of neutron crystallography, one needs accurate Fourier maps depicting atomic structure to a high precision. Special attention is given to subtraction of the high background associated with hydrogen containing molecules, which produces a disproportionately large statistical error.

Vibration sensitivity of the scanning near-field optical microscope with a tapered optical fiber probe.

PubMed

Chang, Win-Jin; Fang, Te-Hua; Lee, Haw-Long; Yang, Yu-Ching

2005-01-01

In this paper the Rayleigh-Ritz method was used to study the scanning near-field optical microscope (SNOM) with a tapered optical fiber probe's flexural and axial sensitivity to vibration. Not only the contact stiffness but also the geometric parameters of the probe can influence the flexural and axial sensitivity to vibration. According to the analysis, the lateral and axial contact stiffness had a significant effect on the sensitivity of vibration of the SNOM's probe, each mode had a different level of sensitivity and in the first mode the tapered optical fiber probe was the most acceptive to higher levels of flexural and axial vibration. Generally, when the contact stiffness was lower, the tapered probe was more sensitive to higher levels of both axial and flexural vibration than the uniform probe. However, the situation was reversed when the contact stiffness was larger. Furthermore, the effect that the probe's length and its tapered angle had on the SNOM's probe axial and flexural vibration were significant and these two conditions should be incorporated into the design of new SNOM probes.

Search for exotic short-range interactions using paramagnetic insulators

DOE PAGES

Chu, Pinghan; Weisman, E.; Liu, C. -Y.; ...

2015-05-26

We describe a proposed experimental search for exotic spin-coupled interactions using a solid-state paramagnetic insulator. The experiment is sensitive to the net magnetization induced by the exotic interaction between the unpaired insulator electrons with a dense, nonmagnetic mass in close proximity. An existing experiment has been used to set limits on the electric dipole moment of the electron by probing the magnetization induced in a cryogenic gadolinium gallium garnet sample on application of a strong electric field. With suitable additions, including a movable source mass, this experiment can be used to explore “monopole-dipole” forces on polarized electrons with unique ormore » unprecedented sensitivity. As a result, the solid-state, nonmagnetic construction, combined with the low-noise conditions and extremely sensitive magnetometry available at cryogenic temperatures could lead to a sensitivity over 10 orders of magnitude greater than exiting limits in the range below 1 mm.« less

Fiber-Optic Imaging Probe Developed for Space Used to Detect Diabetes Through the Eye

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Chenault, Michelle V.; Datiles, Manuel B., III; Sebag, J.; Suh, Kwang I.

2000-01-01

Approximately 16 million Americans have diabetes mellitus, which can severely impair eyesight by causing cataracts, diabetic retinopathy, and glaucoma. Cataracts are 1.6 times more common in people with diabetes than in those without diabetes, and cataract extraction is the only surgical treatment. In many cases, diabetes-related ocular pathologies go undiagnosed until visual function is compromised. This ongoing pilot project seeks to study the progression of diabetes in a unique animal model by monitoring changes in the lens with a safe, sensitive, dynamic light-scattering probe. Dynamic light scattering (DLS), has the potential to diagnose cataracts at the molecular level. Recently, a new DLS fiber-optic probe was developed at the NASA Glenn Research Center at Lewis Field for noncontact, accurate, and extremely sensitive particle-sizing measurements in fluid dispersions and suspensions (ref. 1). This compact, portable, and rugged probe is free of optical alignment, offers point-and-shoot operation for various online field applications and challenging environments, and yet is extremely flexible in regards to sample container sizes, materials, and shapes. No external vibration isolation and no index matching are required. It can measure particles as small as 1 nm and as large as few micrometers in a wide concentration range from very dilute (waterlike) dispersions to very turbid (milklike) suspensions. It is safe and fast to use, since it only requires very low laser power (10 nW to 3 mW) with very short data acquisition times (2 to 10 sec).

Right-handed neutrinos and T-violating, P-conserving interactions

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

El-Menoufi, Basem Kamal; Ramsey-Musolf, Michael J.; Seng, Chien -Yeah

We show that experimental probes of the P-conserving, T-violating triple correlation in polarized neutron or nuclear β-decay provide a unique probe of possible T-violation at the TeV scale in the presence of right-handed neutrinos. In contrast to other possible sources of semileptonic T-violation involving only left-handed neutrinos, those involving right-handed neutrinos are relatively unconstrained by present limits on the permanent electric dipole moments of the electron, neutral atoms, and the neutron. On the other hand, LHC results for pp→e+ missing transverse energy imply that an order of magnitude of improvement in D-coefficient sensitivity would be needed for discovery. Lastly, wemore » discuss the interplay with the scale of neutrino mass and naturalness considerations.« less

Right-handed neutrinos and T-violating, P-conserving interactions

DOE PAGES

El-Menoufi, Basem Kamal; Ramsey-Musolf, Michael J.; Seng, Chien -Yeah

2016-12-02

We show that experimental probes of the P-conserving, T-violating triple correlation in polarized neutron or nuclear β-decay provide a unique probe of possible T-violation at the TeV scale in the presence of right-handed neutrinos. In contrast to other possible sources of semileptonic T-violation involving only left-handed neutrinos, those involving right-handed neutrinos are relatively unconstrained by present limits on the permanent electric dipole moments of the electron, neutral atoms, and the neutron. On the other hand, LHC results for pp→e+ missing transverse energy imply that an order of magnitude of improvement in D-coefficient sensitivity would be needed for discovery. Lastly, wemore » discuss the interplay with the scale of neutrino mass and naturalness considerations.« less

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

Friebel, Daniel

In situ x-ray absorption spectroscopy (XAS) at the Pt L{sub 3} edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard x-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF8 code and complementary extended x-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at highmore » electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.« less

Design rules for biomolecular adhesion: lessons from force measurements.

PubMed

Leckband, Deborah

2010-01-01

Cell adhesion to matrix, other cells, or pathogens plays a pivotal role in many processes in biomolecular engineering. Early macroscopic methods of quantifying adhesion led to the development of quantitative models of cell adhesion and migration. The more recent use of sensitive probes to quantify the forces that alter or manipulate adhesion proteins has revealed much greater functional diversity than was apparent from population average measurements of cell adhesion. This review highlights theoretical and experimental methods that identified force-dependent molecular properties that are central to the biological activity of adhesion proteins. Experimental and theoretical methods emphasized in this review include the surface force apparatus, atomic force microscopy, and vesicle-based probes. Specific examples given illustrate how these tools have revealed unique properties of adhesion proteins and their structural origins.

Anti-epidermal growth factor receptor (anti-EGFR) antibody conjugated fluorescent nanoparticles probe for breast cancer imaging

NASA Astrophysics Data System (ADS)

Hun, Xu; Zhang, Zhujun

2009-10-01

Fluorescent nanoparticles (FNs) with unique optical properties may be useful as biosensors in living cancer cell imaging and cancer targeting. In this study, anti-EGFR antibody conjugated fluorescent nanoparticles (FNs) (anti-EGFR antibody conjugated FNs) probe was used to detect breast cancer cells. FNs with excellent character such as non-toxicity and photostability were first synthesized with a simple, cost-effective and environmentally friendly modified Stőber synthesis method, and then successfully modified with anti-EGFR antibody. This kind of fluorescence probe based on the anti-EGFR antibody conjugated FNs has been used to detect breast cancer cells with fluorescence microscopy imaging technology. The experimental results demonstrate that the anti-EGFR antibody conjugated FNs can effectively recognize breast cancer cells and exhibited good sensitivity and exceptional photostability, which would provide a novel way for the diagnosis and curative effect observation of breast cancer cells and offer a new method in detecting EGFR.

Putative and unique gene sequence utilization for the design of species specific probes as modeled by Lactobacillus plantarum

USDA-ARS?s Scientific Manuscript database

The concept of utilizing putative and unique gene sequences for the design of species specific probes was tested. The abundance profile of assigned functions within the Lactobacillus plantarum genome was used for the identification of the putative and unique gene sequence, csh. The targeted gene (cs...

APPLIED PHYSICS. Mid-infrared plasmonic biosensing with graphene.

PubMed

Rodrigo, Daniel; Limaj, Odeta; Janner, Davide; Etezadi, Dordaneh; García de Abajo, F Javier; Pruneri, Valerio; Altug, Hatice

2015-07-10

Infrared spectroscopy is the technique of choice for chemical identification of biomolecules through their vibrational fingerprints. However, infrared light interacts poorly with nanometric-size molecules. We exploit the unique electro-optical properties of graphene to demonstrate a high-sensitivity tunable plasmonic biosensor for chemically specific label-free detection of protein monolayers. The plasmon resonance of nanostructured graphene is dynamically tuned to selectively probe the protein at different frequencies and extract its complex refractive index. Additionally, the extreme spatial light confinement in graphene—up to two orders of magnitude higher than in metals—produces an unprecedentedly high overlap with nanometric biomolecules, enabling superior sensitivity in the detection of their refractive index and vibrational fingerprints. The combination of tunable spectral selectivity and enhanced sensitivity of graphene opens exciting prospects for biosensing. Copyright © 2015, American Association for the Advancement of Science.

Tandem Payne/Dakin Reaction: A New Strategy for Hydrogen Peroxide Detection and Molecular Imaging.

PubMed

Yang, Dan; Ye, Sen; Hu, Jun Jacob

2018-06-22

Hydrogen peroxide (H2O2) has been recognized as one of the most significant ROS (reactive oxygen species) in human health and disease. Due to the intrinsic attributes of H2O2 such as low reactivity under physiological pH, it is exceedingly challenging to develop small molecule fluorescent probes with high selectivity and sensitivity to visualize H2O2 in intricate biological milieux. To address this gap, we report a rationally designed tandem Payne/Dakin reaction that is specific to molecular recognition of H2O2, and demonstrate its application in developing novel biocompatible fluorescent probes. New H2O2 probes based on this unique chemical strategy can be facilely synthesized by a general coupling reaction, and the practical applicability of those probes has been confirmed by the visualization of endogenously produced H2O2 in living cells. In particular, starvation induced H2O2 production in mouse macrophages has been detected by our novel probe in both confocal imaging and flow cytometry. This tandem Payne/Dakin reaction provides a basis for developing more sophisticated molecular tools to interrogate H2O2 functions in biological phenomena. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical methodology as a source of small-molecule checkpoint inhibitors and heat shock protein 70 (Hsp70) modulators.

PubMed

Huryn, Donna M; Brodsky, Jeffrey L; Brummond, Kay M; Chambers, Peter G; Eyer, Benjamin; Ireland, Alex W; Kawasumi, Masaoki; Laporte, Matthew G; Lloyd, Kayla; Manteau, Baptiste; Nghiem, Paul; Quade, Bettina; Seguin, Sandlin P; Wipf, Peter

2011-04-26

Unique chemical methodology enables the synthesis of innovative and diverse scaffolds and chemotypes and allows access to previously unexplored "chemical space." Compound collections based on such new synthetic methods can provide small-molecule probes of proteins and/or pathways whose functions are not fully understood. We describe the identification, characterization, and evolution of two such probes. In one example, a pathway-based screen for DNA damage checkpoint inhibitors identified a compound, MARPIN (ATM and ATR pathway inhibitor) that sensitizes p53-deficient cells to DNA-damaging agents. Modification of the small molecule and generation of an immobilized probe were used to selectively bind putative protein target(s) responsible for the observed activity. The second example describes a focused library approach that relied on tandem multicomponent reaction methodologies to afford a series of modulators of the heat shock protein 70 (Hsp70) molecular chaperone. The synthesis of libraries based on the structure of MAL3-101 generated a collection of chemotypes, each modulating Hsp70 function, but exhibiting divergent pharmacological activities. For example, probes that compromise the replication of a disease-associated polyomavirus were identified. These projects highlight the importance of chemical methodology development as a source of small-molecule probes and as a drug discovery starting point.

Chemical methodology as a source of small-molecule checkpoint inhibitors and heat shock protein 70 (Hsp70) modulators

PubMed Central

Huryn, Donna M.; Brodsky, Jeffrey L.; Brummond, Kay M.; Chambers, Peter G.; Eyer, Benjamin; Ireland, Alex W.; Kawasumi, Masaoki; LaPorte, Matthew G.; Lloyd, Kayla; Manteau, Baptiste; Nghiem, Paul; Quade, Bettina; Seguin, Sandlin P.; Wipf, Peter

2011-01-01

Unique chemical methodology enables the synthesis of innovative and diverse scaffolds and chemotypes and allows access to previously unexplored “chemical space.” Compound collections based on such new synthetic methods can provide small-molecule probes of proteins and/or pathways whose functions are not fully understood. We describe the identification, characterization, and evolution of two such probes. In one example, a pathway-based screen for DNA damage checkpoint inhibitors identified a compound, MARPIN (ATM and ATR pathway inhibitor) that sensitizes p53-deficient cells to DNA-damaging agents. Modification of the small molecule and generation of an immobilized probe were used to selectively bind putative protein target(s) responsible for the observed activity. The second example describes a focused library approach that relied on tandem multicomponent reaction methodologies to afford a series of modulators of the heat shock protein 70 (Hsp70) molecular chaperone. The synthesis of libraries based on the structure of MAL3-101 generated a collection of chemotypes, each modulating Hsp70 function, but exhibiting divergent pharmacological activities. For example, probes that compromise the replication of a disease-associated polyomavirus were identified. These projects highlight the importance of chemical methodology development as a source of small-molecule probes and as a drug discovery starting point. PMID:21502524

Direct Observation of Individual Charges and Their Dynamics on Graphene by Low-Energy Electron Holography.

PubMed

Latychevskaia, Tatiana; Wicki, Flavio; Longchamp, Jean-Nicolas; Escher, Conrad; Fink, Hans-Werner

2016-09-14

Visualizing individual charges confined to molecules and observing their dynamics with high spatial resolution is a challenge for advancing various fields in science, ranging from mesoscopic physics to electron transfer events in biological molecules. We show here that the high sensitivity of low-energy electrons to local electric fields can be employed to directly visualize individual charged adsorbates and to study their behavior in a quantitative way. This makes electron holography a unique probing tool for directly visualizing charge distributions with a sensitivity of a fraction of an elementary charge. Moreover, spatial resolution in the nanometer range and fast data acquisition inherent to lens-less low-energy electron holography allows for direct visual inspection of charge transfer processes.

Silver nanowires for highly reproducible cantilever based AFM-TERS microscopy: towards a universal TERS probe.

PubMed

Walke, Peter; Fujita, Yasuhiko; Peeters, Wannes; Toyouchi, Shuichi; Frederickx, Wout; De Feyter, Steven; Uji-I, Hiroshi

2018-04-26

Tip-enhanced Raman scattering (TERS) microscopy is a unique analytical tool to provide complementary chemical and topographic information of surfaces with nanometric resolution. However, difficulties in reliably producing the necessary metallized scanning probe tips has limited its widespread utilisation, particularly in the case of cantilever-based atomic force microscopy. Attempts to alleviate tip related issues using colloidal or bottom-up engineered tips have so far not reported consistent probes for both Raman and topographic imaging. Here we demonstrate the reproducible fabrication of cantilever-based high-performance TERS probes for both topographic and Raman measurements, based on an approach that utilises noble metal nanowires as the active TERS probe. The tips show 10 times higher TERS contrasts than the most typically used electrochemically-etched tips, and show a reproducibility for TERS greater than 90%, far greater than found with standard methods. We show that TERS can be performed in tapping as well as contact AFM mode, with optical resolutions around or below 15 nm, and with a maximum resolution achieved in tapping-mode of 6 nm. Our work illustrates that superior TERS probes can be produced in a fast and cost-effective manner using simple wet-chemistry methods, leading to reliable and reproducible high-resolution and high-sensitivity TERS, and thus renders the technique applicable for a broad community.

AnilinoMethylRhodamines: pH Sensitive Probes with Tunable Photophysical Properties by Substituent Effect

PubMed Central

Best, Quinn A.; Liu, Chuangjun; van Hoveln, Paul D.; McCarroll, Matthew E.

2013-01-01

A series of pH dependent rhodamine analogs possessing an anilino-methyl moiety was developed and shown to exhibit a unique photophysical response to pH. These Anilinomethylrhodamines (AnMR) maintain a colorless, non-fluorescent spiro-cyclic structure at high pH. The spiro-cyclic structures open in mildly acidic conditions and are weakly fluorescent; however at very low pH, the fluorescence is greatly enhanced. The equilibrium constants of these processes show a linear response to substituent effects, which was demonstrated by the Hammett equation. PMID:24050117

Design and characterization of planar capacitive imaging probe based on the measurement sensitivity distribution

NASA Astrophysics Data System (ADS)

Yin, X.; Chen, G.; Li, W.; Huthchins, D. A.

2013-01-01

Previous work indicated that the capacitive imaging (CI) technique is a useful NDE tool which can be used on a wide range of materials, including metals, glass/carbon fibre composite materials and concrete. The imaging performance of the CI technique for a given application is determined by design parameters and characteristics of the CI probe. In this paper, a rapid method for calculating the whole probe sensitivity distribution based on the finite element model (FEM) is presented to provide a direct view of the imaging capabilities of the planar CI probe. Sensitivity distributions of CI probes with different geometries were obtained. Influencing factors on sensitivity distribution were studied. Comparisons between CI probes with point-to-point triangular electrode pair and back-to-back triangular electrode pair were made based on the analysis of the corresponding sensitivity distributions. The results indicated that the sensitivity distribution could be useful for optimising the probe design parameters and predicting the imaging performance.

Development of a novel europium complex-based luminescent probe for time-gated luminescence imaging of hypochlorous acid in living samples

NASA Astrophysics Data System (ADS)

Liu, Xiangli; Guo, Lianying; Song, Bo; Tang, Zhixin; Yuan, Jingli

2017-03-01

Luminescent lanthanide complexes are key reagents used in the time-gated luminescence bioassay technique, but functional lanthanide complexes that can act as luminescent probes for specifically responding to analytes are very limited. In this work, we designed and synthesized a novel Eu3+ complex-based luminescence probe for hypochlorous acid (HOCl), NPPTTA-Eu3+, by using terpyridine polyacid-Eu3+, dinitrophenyl, and hydrazine as luminophore, quencher and HOCl-recognizer moieties, respectively. In the absence of HOCl, the probe is non-luminescent due to the strong luminescence quenching of the dinitrophenyl group in the complex. However, upon reaction with HOCl, the dinitrophenyl moiety is rapidly cleaved from the probe, which affords a strongly luminescent Eu3+ complex CPTTA-Eu3+, accompanied by a ˜900-fold luminescence enhancement with a long luminescence lifetime of 1.41 ms. This unique luminescence response of NPPTTA-Eu3+ to HOCl allowed NPPTTA-Eu3+ to be conveniently used as a probe for highly selective and sensitive detection of HOCl under the time-gated luminescence mode. In addition, by loading NPPTTA-Eu3+ into RAW 264.7 macrophage cells and Daphnia magna, the generation of endogenous HOCl in RAW 264.7 cells and the uptake of exogenous HOCl by Daphnia magna were successfully imaged on a true-color time-gated luminescence microscope. The results demonstrated the practical applicability of NPPTTA-Eu3+ as an efficient probe for time-gated luminescence imaging of HOCl in living cells and organisms.

Supramolecular assembly affording a ratiometric two-photon fluorescent nanoprobe for quantitative detection and bioimaging.

PubMed

Wang, Peng; Zhang, Cheng; Liu, Hong-Wen; Xiong, Mengyi; Yin, Sheng-Yan; Yang, Yue; Hu, Xiao-Xiao; Yin, Xia; Zhang, Xiao-Bing; Tan, Weihong

2017-12-01

Fluorescence quantitative analyses for vital biomolecules are in great demand in biomedical science owing to their unique detection advantages with rapid, sensitive, non-damaging and specific identification. However, available fluorescence strategies for quantitative detection are usually hard to design and achieve. Inspired by supramolecular chemistry, a two-photon-excited fluorescent supramolecular nanoplatform ( TPSNP ) was designed for quantitative analysis with three parts: host molecules (β-CD polymers), a guest fluorophore of sensing probes (Np-Ad) and a guest internal reference (NpRh-Ad). In this strategy, the TPSNP possesses the merits of (i) improved water-solubility and biocompatibility; (ii) increased tissue penetration depth for bioimaging by two-photon excitation; (iii) quantitative and tunable assembly of functional guest molecules to obtain optimized detection conditions; (iv) a common approach to avoid the limitation of complicated design by adjustment of sensing probes; and (v) accurate quantitative analysis by virtue of reference molecules. As a proof-of-concept, we utilized the two-photon fluorescent probe NHS-Ad-based TPSNP-1 to realize accurate quantitative analysis of hydrogen sulfide (H 2 S), with high sensitivity and good selectivity in live cells, deep tissues and ex vivo -dissected organs, suggesting that the TPSNP is an ideal quantitative indicator for clinical samples. What's more, TPSNP will pave the way for designing and preparing advanced supramolecular sensors for biosensing and biomedicine.

Nuclear resonance scattering of synchrotron radiation as a unique electronic, structural and thermodynamic probe

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

Alp, E. Ercan; Sturhahn, Wolfgang; Toellner, Thomas S.

2012-05-09

Discovery of Moessbauer effect in a nuclear transition was a remarkable development. It revealed how long-lived nuclear states with relatively low energies in the kiloelectron volt (keV) region can be excited without recoil. This new effect had a unique feature involving a coupling between nuclear physics and solid-state physics, both in terms of physics and sociology. Physics coupling originates from the fact that recoilless emission and absorption or resonance is only possible if the requirement that nuclei have to be bound in a lattice with quantized vibrational states is fulfilled, and that the finite electron density on the nucleus couplesmore » to nuclear degrees of freedom leading to hyperfine interactions. thus, Moessbauer spectroscopy allows peering into solid-state effects using unique nuclear transitions. Sociological aspects of this coupling had been equally startling and fruitful. The interaction between diverse scientific communities, who learned to use Moessbauer spectroscopy proved to be very valuable. For example, biologists, geologists, chemists, physics, materials scientists, and archeologists, all sharing a common spectroscopic technique, also learned to appreciate the beauty and intricacies of each other's fields. As a laboratory-based technique, Moessbauer spectroscopy matured by the end of the 1970s. Further exciting developments took place when accelerator-based techniques were employed, like synchrotron radiation or 'in-beam'Moessbauer experiments with implanted radioactive ions. More recently, two Moessbauer spectrometers on the surface of the Mars kept the technique vibrant and viable up until present time. In this chapter, the authors look into some of the unique aspects of nuclear resonance excited with synchrotron radiation as a probe of condensed matter, including magnetism, valence, vibrations, and lattice dynamics, and review the development of nuclear resonance inelastic x-ray scattering (NRIXS) and synchrotron Moessbauer spectroscopy (SMS). However, to place these two techniques into some perspective with respect to other methods that yield related information, they display their version of a frequently used map of momentum and energy transfer diagram in figure 17.1. Here, various probes like electrons, neutrons, or light, i.e., Brillouin or Raman, and relatively newer forms of X-ray scattering are placed according to their range of energy and momentum transfer taking place during the measurements. Accordingly, NRIXS is a method that needs to be considered as a complementary probe to inelastic neutron and X-ray scattering, while SMS occupies a unique space due to its sensitivity to magnetism, structural deformations, valence, and spin states.« less

Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde

NASA Astrophysics Data System (ADS)

Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

2018-06-01

In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ6-tp)1.5(μ2-Cl)(H2O) (DMF)2]·0.75H2O}n (H2tp = terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X = O, Cl) inorganic chains are linked via these full de-pronated tp2- ligands forming a unique 3D I1O2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu2+ over other cations with high quenching efficiency Ksv value 1.15 × 104 L·mol-1. As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu2+ and benzaldehyde.

Solvo-thermal synthesis of a unique alkaline earth-transition Ba-Cd micro-porous coordination framework as hetero-metallic luminescent sensor for Cu2+ and real-time detection of benzaldehyde.

PubMed

Ding, Bin; Ma, Dian Xue; Zhang, Hui Min; Meng, Xin; Qiu, Rong Rong; Ren, Rong; Wu, Jie; Wu, Xiang Xia; Huo, Jian Zhong; Liu, Yuan Yuan; Shi, Xue Fang

2018-06-15

In this work a unique hetero-metallic alkaline earth-transition Ba-Cd luminescent micro-porous metal-organic framework {[BaCd(μ 6 -tp) 1.5 (μ 2 -Cl)(H 2 O) (DMF) 2 ]·0.75H 2 O} n (H 2 tp=terephthalic acid) (1) has been prepared under solvo-thermal conditions. In 1 infinite 1D {Ba-X-Cd} (X=O, Cl) inorganic chains are linked via these full de-pronated tp 2- ligands forming a unique 3D I 1 O 2 type micro-porous coordination framework. PXRD patterns of 1 have been determined confirming pure phases of 1. Luminescence investigations suggested that 1 exhibits highly selective and sensitive sensing for trace amounts of benzaldehyde in ethanol, which provides a facile method for real-time detection of benzaldehyde. Meanwhile 1 also exhibits highly selective and sensitive sensing for Cu 2+ over other cations with high quenching efficiency K sv value 1.15×10 4 L·mol -1 . As far as we know, 1 represents the first example of alkaline earth-transition hetero-metallic Ba-Cd micro-porous coordination framework as bi-functional luminescent probes for Cu 2+ and benzaldehyde. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluorescence lifetime as a new parameter in analytical cytology measurements

NASA Astrophysics Data System (ADS)

Steinkamp, John A.; Deka, Chiranjit; Lehnert, Bruce E.; Crissman, Harry A.

1996-05-01

A phase-sensitive flow cytometer has been developed to quantify fluorescence decay lifetimes on fluorochrome-labeled cells/particles. This instrument combines flow cytometry (FCM) and frequency-domain fluorescence spectroscopy measurement principles to provide unique capabilities for making phase-resolved lifetime measurements, while preserving conventional FCM capabilities. Cells are analyzed as they intersect a high-frequency, intensity-modulated (sine wave) laser excitation beam. Fluorescence signals are processed by conventional and phase-sensitive signal detection electronics and displayed as frequency distribution histograms. In this study we describe results of fluorescence intensity and lifetime measurements on fluorescently labeled particles, cells, and chromosomes. Examples of measurements on intrinsic cellular autofluorescence, cells labeled with immunofluorescence markers for cell- surface antigens, mitochondria stains, and on cellular DNA and protein binding fluorochromes will be presented to illustrate unique differences in measured lifetimes and changes caused by fluorescence quenching. This innovative technology will be used to probe fluorochrome/molecular interactions in the microenvironment of cells/chromosomes as a new parameter and thus expand the researchers' understanding of biochemical processes and structural features at the cellular and molecular level.

Measurement Sensitivity Of Liquid Droplet Parameters Using Optical Fibers

NASA Astrophysics Data System (ADS)

Das, Alok K.; Mandal, Anup K.

1990-02-01

A new clad probing technique is used to measure the size, number, refractive index and viscosity of liquid droplets sprayed from a pressure nozzle on an uncoated core-clad fiber. The probe monitors the clad mode power loss within the leaky ray zone represented as a three region fiber. Liquid droplets measured are Glycerine, commercial grade Turpentine, Linseed oil and some oil mixtures. The measurement sensitivity depends on probing conditions and clad diameter which is observed experimentally and verified analytically. A maximum sensitivity is obtained for the tapered probe-fiber diameter made equal to the clad thickness. A slowly tapered probe-fiber and a small end angle as well as separation of the sensor-fiber and the probe-fiber further improve the sensitivity. Under the best probing condition for 90-percent Glycerine droplets of - 50 micron diameter and a 50/125 micron sensor fiber with clad refractive index of 1.465 and 0.2 NA, the measured sensitivity per drop is 0.015 and 0.006 dB, respectively, for (10-20) and (100-200) droplets. Sensitivities for different systems are shown. The sensitivity is optimized by choosing proper fiber for known liquids.

Analysis of acoustic and entropy disturbances in a hypersonic wind tunnel

NASA Astrophysics Data System (ADS)

Schilden, Thomas; Schröder, Wolfgang; Ali, Syed Raza Christopher; Schreyer, Anne-Marie; Wu, Jie; Radespiel, Rolf

2016-05-01

The tunnel noise in a Mach 5.9 Ludwieg tube is determined by two methods, a newly developed cone-probe-DNS method and a reliable hot-wire-Pitot-probe method. The new method combines pressure and heat flux measurements using a cone probe and direct numerical simulation (DNS). The modal analysis is based on transfer functions obtained by the DNS to link the measured quantities to the tunnel noise. The measurements are performed for several unit-Reynolds numbers in the range of 5 ṡ 106 ≤ Re/m ≤ 16 ṡ 106 and probe positions to identify the sensitivities of tunnel noise. The DNS solutions show similar response mechanisms of the cone probe to incident acoustic and entropy waves which leads to high condition numbers of the transfer matrix such that a unique relationship between response and source mechanism can be only determined by neglecting the contribution of the non-acoustic modes to the pressure and heat flux fluctuations. The results of the cone-probe-DNS method are compared to a modal analysis based on the hot-wire-Pitot-probe method which provides reliable results in the frequency range less than 50 kHz. In this low frequency range the findings of the two different mode analyses agree well. At higher frequencies, the newly developed cone-probe-DNS method is still valid. The tunnel noise is dominated by the acoustic mode, since the entropy mode is lower by one order of magnitude and the vorticity mode can be neglected. The acoustic mode is approximately 0.5% at 30 kHz and the cone-probe-DNS data illustrate the acoustic mode to decrease and to asymptotically approach 0.2%.

Discovery of a novel calcium-sensitive fluorescent probe for α-ketoglutarate.

PubMed

Gan, Lin-Lin; Chen, Lin-Hai; Nan, Fa-Jun

2017-12-01

α-Ketoglutarate (α-KG), a pivotal metabolite in energy metabolism, has been implicated in nonalcoholic fatty liver disease (NAFLD) and several cancers. It is recently proposed that plasma α-KG is a surrogate biomarker of NAFLD. Here, we report the development of a novel "turn-on" chemosensor for α-KG that contains a coumarin moiety as a fluorophore. Using benzothiazole-coumarin (BTC) as inspiration, we designed a probe for calcium ion recognition that possesses a unique fluorophore compared with previously reported probes for α-KG measurement. This chemosensor is based on the specific Schiff base reaction and the calcium ion recognition property of the widely used calcium indicator BTC. The probe was synthesized, and a series of parallel experiments were conducted to optimize the chemical recognition process. Compared to the initial weak fluorescence, a remarkable 7.6-fold enhancement in fluorescence intensity (I/I 0 at 495 nm) was observed for the conditions in which the probe (1 μmol/L), α-KG (50 μmol/L), and Ca 2+ (100 μmol/L) were incubated at 30 °C in EtOH. The probe displayed good selectivity for α-KG even in an environment with an abundance of amino acids and other interfering species such as glutaric acid. We determined that the quantitative detection range of α-KG in EtOH was between 5 and 50 μmol/L. Finally, probe in serum loaded with α-KG (10 mmol/L) showed a 7.4-fold fluorescence enhancement. In summary, a novel probe for detecting the biomarker α-KG through a typical Schiff base reaction has been discovered. With further optimization, this probe may be a good alternative for detecting the physiological metabolite α-KG.

Accuracy of line probe assays for the diagnosis of pulmonary and multidrug-resistant tuberculosis: a systematic review and meta-analysis

PubMed Central

Cudahy, Patrick G.T; Schumacher, Samuel G.; Steingart, Karen R.; Pai, Madhukar; Denkinger, Claudia M.

2017-01-01

Only 25% of multidrug-resistant tuberculosis (MDR-TB) cases are currently diagnosed. Line probe assays (LPAs) enable rapid drug-susceptibility testing for rifampicin (RIF) and isoniazid (INH) resistance and Mycobacterium tuberculosis detection. Genotype MTBDRplusV1 was WHO-endorsed in 2008 but newer LPAs have since been developed. This systematic review evaluated three LPAs: Hain Genotype MTBDRplusV1, MTBDRplusV2 and Nipro NTM+MDRTB. Study quality was assessed with QUADAS-2. Bivariate random-effects meta-analyses were performed for direct and indirect testing. Results for RIF and INH resistance were compared to phenotypic and composite (incorporating sequencing) reference standards. M. tuberculosis detection results were compared to culture. 74 unique studies were included. For RIF resistance (21 225 samples), pooled sensitivity and specificity (with 95% confidence intervals) were 96.7% (95.6–97.5%) and 98.8% (98.2–99.2%). For INH resistance (20 954 samples), pooled sensitivity and specificity were 90.2% (88.2–91.9%) and 99.2% (98.7–99.5%). Results were similar for direct and indirect testing and across LPAs. Using a composite reference standard, specificity increased marginally. For M. tuberculosis detection (3451 samples), pooled sensitivity was 94% (89.4–99.4%) for smear-positive specimens and 44% (20.2–71.7%) for smear-negative specimens. In patients with pulmonary TB, LPAs have high sensitivity and specificity for RIF resistance and high specificity and good sensitivity for INH resistance. This meta-analysis provides evidence for policy and practice. PMID:28100546

Advances in Probes and Methods for Clinical EPR Oximetry

PubMed Central

Hou, Huagang; Khan, Nadeem; Jarvis, Lesley A.; Chen, Eunice Y.; Williams, Benjamin B.; Kuppusamy, Periannan

2015-01-01

EPR oximetry, which enables reliable, accurate, and repeated measurements of the partial pressure of oxygen in tissues, provides a unique opportunity to investigate the role of oxygen in the pathogenesis and treatment of several diseases including cancer, stroke, and heart failure. Building on significant advances in the in vivo application of EPR oximetry for small animal models of disease, we are developing suitable probes and instrumentation required for use in human subjects. Our laboratory has established the feasibility of clinical EPR oximetry in cancer patients using India ink, the only material presently approved for clinical use. We now are developing the next generation of probes, which are both superior in terms of oxygen sensitivity and biocompatibility including an excellent safety profile for use in humans. Further advances include the development of implantable oxygen sensors linked to an external coupling loop for measurements of deep-tissue oxygenations at any depth, overcoming the current limitation of 10 mm. This paper presents an overview of recent developments in our ability to make meaningful measurements of oxygen partial pressures in human subjects under clinical settings. PMID:24729217

Low energy positrons as probes of reconstructed semiconductor surfaces.

NASA Astrophysics Data System (ADS)

Fazleev, Nail G.; Weiss, Alex H.

2007-03-01

Positron probes of semiconductor surfaces that play a fundamental role in modern science and technology are capable to non-destructively provide information that is both unique to the probe and complimentary to that extracted using other more standard techniques. We discuss recent progress in studies of the reconstructed Si(100), Si(111), Ge(100), and Ge(111) surfaces, clean and exposed to hydrogen and oxygen, using a surface characterization technique, Positron-Annihilation-Induced Auger-Electron Spectroscopy (PAES). Experimental PAES results are analyzed by performing first-principles calculations of positron surface states and annihilation probabilities of surface-trapped positrons with relevant core electrons for the reconstructed surfaces, taking into account discrete lattice effects, the electronic reorganization due to bonding, and charge redistribution effects at the surface. Effects of the hydrogen and oxygen adsorption on semiconductor surfaces on localization of positron surface state wave functions and annihilation characteristics are also analyzed. Theoretical calculations confirm that PAES intensities, which are proportional to annihilation probabilities of the surface trapped positrons that results in a core hole, are sensitive to the crystal face, surface structure and elemental content of the semiconductors.

Probing condensed matter physics with magnetometry based on nitrogen-vacancy centres in diamond

NASA Astrophysics Data System (ADS)

Casola, Francesco; van der Sar, Toeno; Yacoby, Amir

2018-01-01

The magnetic fields generated by spins and currents provide a unique window into the physics of correlated-electron materials and devices. First proposed only a decade ago, magnetometry based on the electron spin of nitrogen-vacancy (NV) defects in diamond is emerging as a platform that is excellently suited for probing condensed matter systems; it can be operated from cryogenic temperatures to above room temperature, has a dynamic range spanning from direct current to gigahertz and allows sensor-sample distances as small as a few nanometres. As such, NV magnetometry provides access to static and dynamic magnetic and electronic phenomena with nanoscale spatial resolution. Pioneering work has focused on proof-of-principle demonstrations of its nanoscale imaging resolution and magnetic field sensitivity. Now, experiments are starting to probe the correlated-electron physics of magnets and superconductors and to explore the current distributions in low-dimensional materials. In this Review, we discuss the application of NV magnetometry to the exploration of condensed matter physics, focusing on its use to study static and dynamic magnetic textures and static and dynamic current distributions.

Optical fiber-based fluorescent viscosity sensor

NASA Astrophysics Data System (ADS)

Haidekker, Mark A.; Akers, Walter J.; Fischer, Derek; Theodorakis, Emmanuel A.

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

Optical fiber-based fluorescent viscosity sensor.

PubMed

Haidekker, Mark A; Akers, Walter J; Fischer, Derek; Theodorakis, Emmanuel A

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

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

Chen, Wei; Rosser, Ethan W.; Zhang, Di

Hydrogen polysulfides (H 2S n, n>1) have been recently suggested to be the actual signalling molecules that involved in sulfur-related redox biology. However the exact mechanisms of H 2S n are still poorly understood and a major hurdle in this field is the lack of reliable and convenient methods for H 2S n detection. In this work we report a unique ring-opening reaction of N-sulfonylaziridine by Na 2S 2 under mild conditions. Based on this reaction a novel H 2S n-specific fluorescent probe (AP) was developed. The probe showed high sensitivity and selectivity for H 2S n. Notably, the fluorescentmore » turn-on product, i.e. compound 1, exhibited excellent two-photon photophysical properties and a large Stokes shift. Moreover, the high solid state luminescent efficiency of compound 1 makes it a potential candidate for organic emitters and solid-state lighting devices.« less

Messenger RNA Detection in Leukemia Cell lines by Novel Metal-Tagged in situ Hybridization using Inductively Coupled Plasma Mass Spectrometry.

PubMed

Ornatsky, Olga I; Baranov, Vladimir I; Bandura, Dmitry R; Tanner, Scott D; Dick, John

2006-01-01

Conventional gene expression profiling relies on using fluorescent detection of hybridized probes. Physical characteristics of fluorophores impose limitations on achieving a highly multiplex gene analysis of single cells. Our work demonstrates the feasibility of using metal-tagged in situ hybridization for mRNA detection by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS as an analytical detector has a number of unique and relevant properties: 1) metals and their stable isotopes generate non-overlapping distinct signals that can be detected simultaneously; 2) these signals can be measured over a wide dynamic range; 3) ICP-MS is quantitative and very sensitive. We used commercial antibodies conjugated to europium (Eu) and gold together with biotinylated oligonucleotide probes reacted with terbium-labeled streptavidin to demonstrate simultaneous mRNA and protein detection by ICP-MS in leukemia cells.

Messenger RNA Detection in Leukemia Cell lines by Novel Metal-Tagged in situ Hybridization using Inductively Coupled Plasma Mass Spectrometry

PubMed Central

Ornatsky, Olga I.; Baranov, Vladimir I.; Bandura, Dmitry R.; Tanner, Scott D.; Dick, John

2006-01-01

Conventional gene expression profiling relies on using fluorescent detection of hybridized probes. Physical characteristics of fluorophores impose limitations on achieving a highly multiplex gene analysis of single cells. Our work demonstrates the feasibility of using metal-tagged in situ hybridization for mRNA detection by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS as an analytical detector has a number of unique and relevant properties: 1) metals and their stable isotopes generate non-overlapping distinct signals that can be detected simultaneously; 2) these signals can be measured over a wide dynamic range; 3) ICP-MS is quantitative and very sensitive. We used commercial antibodies conjugated to europium (Eu) and gold together with biotinylated oligonucleotide probes reacted with terbium-labeled streptavidin to demonstrate simultaneous mRNA and protein detection by ICP-MS in leukemia cells. PMID:23662035

Compressor blade clearance measurement using capacitance and phase lock techniques

NASA Astrophysics Data System (ADS)

Demers, Rosario N.

1986-11-01

The clearance measurement system has several unique features which mimimize problems plaguing earlier systems. These include tuning stability and sensitivity drift. Both these problems are intensified by the environmental factors present in compressors i.e., wide temperature fluctuations, vibrations, and conductive contamination of probe tips. The circuitry in this new system provides phase lock feedback to control tuning and shut calibration to measure sensitivity. The use of high frequency excitation lowers the probe tip impedance, thus miminizing the effects of contamination. A prototype has been built and tested. The ability to calibrate has been demonstrated. An eight channel system is now being constructed for use in the Compressor Research Facility at Wright-Patterson AFB. The efficiency of a turbine engine is to a large extent dependent upon the mechanical tolerances maintained between its moving parts. On critical tolerance is the blade span. Although this tolerance may not appear severe, the impact on compressor efficiency is dramatic. The penalty in percent efficiency has been shown to be three times the percent clearance to blade span ratio. In addition, each percent loss in compressor efficiency represents one half percent loss in specific fuel consumption. Factors which affect blade tip clearance are identified.

Golden probe of electroweak symmetry breaking

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

Chen, Yi; Lykken, Joe; Spiropulu, Maria

The ratio of the Higgs couplings tomore » $WW$ and $ZZ$ pairs, $$\\lambda_{WZ}$$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of $$\\lambda_{WZ}$$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $$h\\to4\\ell$$ ($$4\\ell \\equiv 2e2\\mu, 4e, 4\\mu$$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $$h\\to4\\ell$$ to the magnitude of $$\\lambda_{WZ}$$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. Furthermore, this makes $$h\\to4\\ell$$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.« less

Golden probe of electroweak symmetry breaking

DOE PAGES

Chen, Yi; Lykken, Joe; Spiropulu, Maria; ...

2016-12-09

The ratio of the Higgs couplings tomore » $WW$ and $ZZ$ pairs, $$\\lambda_{WZ}$$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of $$\\lambda_{WZ}$$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $$h\\to4\\ell$$ ($$4\\ell \\equiv 2e2\\mu, 4e, 4\\mu$$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $$h\\to4\\ell$$ to the magnitude of $$\\lambda_{WZ}$$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumptions about the top quark Yukawa couplings which also enter at 1-loop. Furthermore, this makes $$h\\to4\\ell$$ a unique and independent probe of the electroweak symmetry breaking mechanism and custodial symmetry.« less

Polyhedral Oligomeric Silsesquioxane Polymer-Caged Silver Nanoparticle as a Smart Colorimetric Probe for the Detection of Hydrogen Sulfide.

PubMed

Zhang, Yue; Shen, Hui-Yan; Hai, Xin; Chen, Xu-Wei; Wang, Jian-Hua

2017-01-17

The rapid and accurate detection of hydrogen sulfide is of great concern due to its unique role on environmental pollution and signal transmission in physiological systems. Herein, we report a smart colorimetric probe for the selective detection of H 2 S. The probe is prepared via a surfactant-free route with cross-linked polyhedral oligomeric silsesquioxane (POSS) polymer cage as capping ligand and reducing agent under microwave irradiation, called poly-POSS-formaldehyde polymer (PPF) cage-AgNPs or PPF-AgNPs for short. The caged silver nanoparticles are well-dispersed with narrow size distribution within 6.0-8.4 nm. Chloride ions and aldehyde groups in PPF make the nucleation and growth of Ag nanoparticles accomplished within a very short time of 1 min. The positively charged PPF-AgNPs exhibit excellent selectivity to H 2 S against other anionic species and thiols due to the specific Ag-H 2 S interaction, where the favorable protection effect of PPF polymer cage from the nanoparticle aggregation is demonstrated. The colorimetric probe presents a quick response to H 2 S (<3 min) and favorable sensitivity within a linear range of 0.7-10 μM along with a detection limit of 0.2 μM. The probe is well demonstrated by analysis of H 2 S in various water and biological samples.

Electron Paramagnetic Resonance Measurements of Reactive Oxygen Species by Cyclic Hydroxylamine Spin Probes.

PubMed

Dikalov, Sergey I; Polienko, Yuliya F; Kirilyuk, Igor

2018-05-20

Oxidative stress contributes to numerous pathophysiological conditions such as development of cancer, neurodegenerative, and cardiovascular diseases. A variety of measurements of oxidative stress markers in biological systems have been developed; however, many of these methods are not specific, can produce artifacts, and do not directly detect the free radicals and reactive oxygen species (ROS) that cause oxidative stress. Electron paramagnetic resonance (EPR) is a unique tool that allows direct measurements of free radical species. Cyclic hydroxylamines are useful and convenient molecular probes that readily react with ROS to produce stable nitroxide radicals, which can be quantitatively measured by EPR. In this work, we critically review recent applications of various cyclic hydroxylamine spin probes in biology to study oxidative stress, their advantages, and the shortcomings. Recent Advances: In the past decade, a number of new cyclic hydroxylamine spin probes have been developed and their successful application for ROS measurement using EPR has been published. These new state-of-the-art methods provide improved selectivity and sensitivity for in vitro and in vivo studies. Although cyclic hydroxylamine spin probes EPR application has been previously described, there has been lack of translation of these new methods into biomedical research, limiting their widespread use. This work summarizes "best practice" in applications of cyclic hydroxylamine spin probes to assist with EPR studies of oxidative stress. Additional studies to advance hydroxylamine spin probes from the "basic science" to biomedical applications are needed and could lead to better understanding of pathological conditions associated with oxidative stress. Antioxid. Redox Signal. 28, 1433-1443.

RUCS: rapid identification of PCR primers for unique core sequences.

PubMed

Thomsen, Martin Christen Frølund; Hasman, Henrik; Westh, Henrik; Kaya, Hülya; Lund, Ole

2017-12-15

Designing PCR primers to target a specific selection of whole genome sequenced strains can be a long, arduous and sometimes impractical task. Such tasks would benefit greatly from an automated tool to both identify unique targets, and to validate the vast number of potential primer pairs for the targets in silico. Here we present RUCS, a program that will find PCR primer pairs and probes for the unique core sequences of a positive genome dataset complement to a negative genome dataset. The resulting primer pairs and probes are in addition to simple selection also validated through a complex in silico PCR simulation. We compared our method, which identifies the unique core sequences, against an existing tool called ssGeneFinder, and found that our method was 6.5-20 times more sensitive. We used RUCS to design primer pairs that would target a set of genomes known to contain the mcr-1 colistin resistance gene. Three of the predicted pairs were chosen for experimental validation using PCR and gel electrophoresis. All three pairs successfully produced an amplicon with the target length for the samples containing mcr-1 and no amplification products were produced for the negative samples. The novel methods presented in this manuscript can reduce the time needed to identify target sequences, and provide a quick virtual PCR validation to eliminate time wasted on ambiguously binding primers. Source code is freely available on https://bitbucket.org/genomicepidemiology/rucs. Web service is freely available on https://cge.cbs.dtu.dk/services/RUCS. mcft@cbs.dtu.dk. Supplementary data are available at Bioinformatics online. © The Author(s) 2017. Published by Oxford University Press.

High sensitive and direct fluorescence detection of single viral DNA sequences by integration of double strand probes onto microgels particles.

PubMed

Aliberti, A; Cusano, A M; Battista, E; Causa, F; Netti, P A

2016-02-21

A novel class of probes for fluorescence detection was developed and combined to microgel particles for a high sensitive fluorescence detection of nucleic acids. A double strand probe with an optimized fluorescent-quencher couple was designed for the detection of different lengths of nucleic acids (39 nt and 100 nt). Such probe proved efficient in target detection in different contests and specific even in presence of serum proteins. The conjugation of double strand probes onto polymeric microgels allows for a sensitive detection of DNA sequences from HIV, HCV and SARS corona viruses with a LOD of 1.4 fM, 3.7 fM and 1.4 fM, respectively, and with a dynamic range of 10(-9)-10(-15) M. Such combination enhances the sensitivity of the detection of almost five orders of magnitude when compared to the only probe. The proposed platform based on the integration of innovative double strand probe into microgels particles represents an attractive alternative to conventional sensitive DNA detection technologies that rely on amplifications methods.

Dual lanthanide-doped complexes: the development of a time-resolved ratiometric fluorescent probe for anthrax biomarker and a paper-based visual sensor.

PubMed

Wang, Qi-Xian; Xue, Shi-Fan; Chen, Zi-Han; Ma, Shi-Hui; Zhang, Shengqiang; Shi, Guoyue; Zhang, Min

2017-08-15

In this work, a novel time-resolved ratiometric fluorescent probe based on dual lanthanide (Tb: terbium, and Eu: europium)-doped complexes (Tb/DPA@SiO 2 -Eu/GMP) has been designed for detecting anthrax biomarker (dipicolinic acid, DPA), a unique and major component of anthrax spores. In such complexes-based probe, Tb/DPA@SiO 2 can serve as a stable reference signal with green fluorescence and Eu/GMP act as a sensitive response signal with red fluorescence for ratiometric fluorescent sensing DPA. Additionally, the probe exhibits long fluorescence lifetime, which can significantly reduce the autofluorescence interferences from biological samples by using time-resolved fluorescence measurement. More significantly, a paper-based visual sensor for DPA has been devised by using filter paper embedded with Tb/DPA@SiO 2 -Eu/GMP, and we have proved its utility for fluorescent detection of DPA, in which only a handheld UV lamp is used. In the presence of DPA, the paper-based visual sensor, illuminated by a handheld UV lamp, would result in an obvious fluorescence color change from green to red, which can be easily observed with naked eyes. The paper-based visual sensor is stable, portable, disposable, cost-effective and easy-to-use. The feasibility of using a smartphone with easy-to-access color-scanning APP as the detection platform for quantitative scanometric assays has been also demonstrated by coupled with our proposed paper-based visual sensor. This work unveils an effective method for accurate, sensitive and selective monitoring anthrax biomarker with backgroud-free and self-calibrating properties. Copyright © 2017 Elsevier B.V. All rights reserved.

An Electrochemiluminescence Immunosensor Based on Gold-Magnetic Nanoparticles and Phage Displayed Antibodies

PubMed Central

Mu, Xihui; Tong, Zhaoyang; Huang, Qibin; Liu, Bing; Liu, Zhiwei; Hao, Lanqun; Dong, Hua; Zhang, Jinping; Gao, Chuan

2016-01-01

Using the multiple advantages of the ultra-highly sensitive electrochemiluminescence (ECL) technique, Staphylococcus protein A (SPA) functionalized gold-magnetic nanoparticles and phage displayed antibodies, and using gold-magnetic nanoparticles coated with SPA and coupled with a polyclonal antibody (pcAb) as magnetic capturing probes, and Ru(bpy)32+-labeled phage displayed antibody as a specific luminescence probe, this study reports a new way to detect ricin with a highly sensitive and specific ECL immunosensor and amplify specific detection signals. The linear detection range of the sensor was 0.0001~200 µg/L, and the limit of detection (LOD) was 0.0001 µg/L, which is 2500-fold lower than that of the conventional ELISA technique. The gold-magnetic nanoparticles, SPA and Ru(bpy)32+-labeled phage displayed antibody displayed different amplifying effects in the ECL immunosensor and can decrease LOD 3-fold, 3-fold and 20-fold, respectively, compared with the ECL immunosensors without one of the three effects. The integrated amplifying effect can decrease the LOD 180-fold. The immunosensor integrates the unique advantages of SPA-coated gold-magnetic nanoparticles that improve the activity of the functionalized capturing probe, and the amplifying effect of the Ru(bpy)32+-labeled phage displayed antibodies, so it increases specificity, interference-resistance and decreases LOD. It is proven to be well suited for the analysis of trace amounts of ricin in various environmental samples with high recovery ratios and reproducibility. PMID:26927130

DNA Clutch Probes for Circulating Tumor DNA Analysis.

PubMed

Das, Jagotamoy; Ivanov, Ivaylo; Sargent, Edward H; Kelley, Shana O

2016-08-31

Progress toward the development of minimally invasive liquid biopsies of disease is being bolstered by breakthroughs in the analysis of circulating tumor DNA (ctDNA): DNA released from cancer cells into the bloodstream. However, robust, sensitive, and specific methods of detecting this emerging analyte are lacking. ctDNA analysis has unique challenges, since it is imperative to distinguish circulating DNA from normal cells vs mutation-bearing sequences originating from tumors. Here we report the electrochemical detection of mutated ctDNA in samples collected from cancer patients. By developing a strategy relying on the use of DNA clutch probes (DCPs) that render specific sequences of ctDNA accessible, we were able to readout the presence of mutated ctDNA. DCPs prevent reassociation of denatured DNA strands: they make one of the two strands of a dsDNA accessible for hybridization to a probe, and they also deactivate other closely related sequences in solution. DCPs ensure thereby that only mutated sequences associate with chip-based sensors detecting hybridization events. The assay exhibits excellent sensitivity and specificity in the detection of mutated ctDNA: it detects 1 fg/μL of a target mutation in the presence of 100 pg/μL of wild-type DNA, corresponding to detecting mutations at a level of 0.01% relative to wild type. This approach allows accurate analysis of samples collected from lung cancer and melanoma patients. This work represents the first detection of ctDNA without enzymatic amplification.

Comparison of randomly cloned and whole genomic DNA probes for the detection of Porphyromonas gingivalis and Bacteroides forsythus

PubMed Central

Wong, M.; DiRienzo, J.M.; Lai, C.-H.; Listgarten, M. A.

2012-01-01

Whole genomic and randomly-cloned DNA probes for two fastidious periodontal pathogens, Porphyromonas gingivalis and Bacteroides forsythus were labeled with digoxigenin and detected by a colorimetric method. The specificity and sensitivity of the whole genomic and cloned probes were compared. The cloned probes were highly specific compared to the whole genomic probes. A significant degree of cross-reactivity with Bacteroides species. Capnocytophaga sp. and Prevotella sp. was observed with the whole genomic probes. The cloned probes were less sensitive than the whole genomic probes and required at least 106 target cells or a minimum of 10 ng of target DNA to be detected during hybridization. Although a ten-fold increase in sensitivity was obtained with the whole genomic probes, cross-hybridization to closely related species limits their reliability in identifying target bacteria in subgingival plaque samples. PMID:8636873

Trityl radicals in perfluorocarbon emulsions as stable, sensitive, and biocompatible oximetry probes.

PubMed

Dhimitruka, Ilirian; Alzarie, Yasmin Alsayed; Hemann, Craig; Samouilov, Alexandre; Zweier, Jay L

2016-12-01

EPR oximetry with the use of trityl radicals can enable sensitive O 2 measurement in biological cells and tissues. However, in vitro cellular and in vivo biological applications are limited by rapid trityl probe degradation or biological clearance and the need to enhance probe O 2 sensitivity. We synthesized novel perfluorocarbon (PFC) emulsions, ∼200nm droplet size, containing esterified perchlorinated triphenyl methyl (PTM) radicals dispersed in physiological aqueous buffers. These formulations exhibit excellent EPR signal stability, over 20-fold greater than free PTM probes, with high oxygen sensitivity ∼17mG/mmHg enabling pO 2 measurement in aqueous solutions or cell suspensions with sensitivity >0.5mmHg. Thus, PFC-PTM probes hold great promise to enable combined O 2 delivery and sensing as needed to restore or enhance tissue oxygenation in disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Absolute mass of neutrinos and the first unique forbidden {beta} decay of {sup 187}Re

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

Dvornicky, Rastislav; Simkovic, Fedor; Bogoliubov Laboratory of Theoretical Physics, JINR Dubna, 141980 Dubna, Moscow region

2011-04-15

The planned rhenium {beta}-decay experiment, called the ''Microcalorimeter Arrays for a Rhenium Experiment'' (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which will take commissioning data in 2011 and will proceed for 5 years. We present the energy distribution of emitted electrons for the first unique forbidden {beta} decay of {sup 187}Re. It is found that the p-wave emission of electron dominates over the s wave. By assuming mixing of three neutrinos, the Kurie function for the rhenium {beta} decay is derived. It is shown that themore » Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed {beta} decay of {sup 3}H.« less

Dual-Reactable Fluorescent Probes for Highly Selective and Sensitive Detection of Biological H2 S.

PubMed

Wei, Chao; Wang, Runyu; Zhang, Changyu; Xu, Guoce; Li, Yanyan; Zhang, Qiang-Zhe; Li, Lu-Yuan; Yi, Long; Xi, Zhen

2016-05-06

Hydrogen sulfide (H2 S) is an important endogenous signaling molecule with a variety of biological functions. Development of fluorescent probes for highly selective and sensitive detection of H2 S is necessary. We show here that dual-reactable fluorescent H2 S probes could react with higher selectivity than single-reactable probes. One of the dual-reactable probes gives more than 4000-fold turn-on response when reacting with H2 S, the largest response among fluorescent H2 S probes reported thus far. In addition, the probe could be used for high-throughput enzymatic assays and for the detection of Cys-induced H2 S in cells and in zebrafish. These dual-reactable probes hold potential for highly selective and sensitive detection of H2 S in biological systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mass Spectrometry for Planetary Probes: Past, Present and Future

NASA Technical Reports Server (NTRS)

Niemann, Hasso B.; Harpold, Dan N.; Jamieson, Brian G.; Mahaffy, Paul R.

2005-01-01

Atmospheric entry probes present a unique opportunity for performing quantitative analysis of extra-terrestrial atmospheres in cases where remote sensing alone may not be sufficient and measurements with balloons or aircraft is not practical. An entry probe can provide a complete vertical profile of atmospheric parameters including chemical composition, which cannot be obtained with most other techniques. There are, however, unique challenges associated with building instruments for an entry probe, as compared to orbiters, landers, or rovers. Conditions during atmospheric entry are extreme, there are inherent time constraints due to the short duration of the experiment, and the instrument experiences rapid environmental changes in temperature and pressure as it descends. In addition, there are resource limitations, i.e. mass, power, size and bandwidth. Finally, the demands on the instrument design are determined in large part by conditions (pressure, temperature, composition) unique to the particular body under study, and as a result there is no one-size-fits-all instrument for an atmospheric probe. Many of these requirements can be more easily met by miniaturizing the probe instrument. Our experience building mass spectrometers for atmospheric entry probes leads us to believe that the time is right for a fundamental change in the way spaceflight mass spectrometers are built. The emergence over the past twenty years of Micro-electro- mechanical Systems (MEMS), utilizing lithographic semiconductor fabrication techniques to produce instrument systems in miniature, holds great promise for application to spaceflight mass spectrometry. A highly miniaturized, high performance and low-power mass spectrometer would be an enormous benefit to future entry probe missions, allowing, for example, parallel measurements (e.g., multiple simultaneous gas chromatographic analyses and direct atmospheric leaks.) Such an instrument would also enable mass spectrometry on board small multiple entry probes. In the development of a MEMS Mass Spectrometer, the challenge facing us is to move beyond the proof-of-concept, where research dollars tend to focus, and carry out the detailed work of developing a high performance mass spectrometer system on a chip which meets the unique technical requirements for an atmospheric entry probe described above.

Synthetic oligonucleotide probes deduced from amino acid sequence data. Theoretical and practical considerations.

PubMed

Lathe, R

1985-05-05

Synthetic probes deduced from amino acid sequence data are widely used to detect cognate coding sequences in libraries of cloned DNA segments. The redundancy of the genetic code dictates that a choice must be made between (1) a mixture of probes reflecting all codon combinations, and (2) a single longer "optimal" probe. The second strategy is examined in detail. The frequency of sequences matching a given probe by chance alone can be determined and also the frequency of sequences closely resembling the probe and contributing to the hybridization background. Gene banks cannot be treated as random associations of the four nucleotides, and probe sequences deduced from amino acid sequence data occur more often than predicted by chance alone. Probe lengths must be increased to confer the necessary specificity. Examination of hybrids formed between unique homologous probes and their cognate targets reveals that short stretches of perfect homology occurring by chance make a significant contribution to the hybridization background. Statistical methods for improving homology are examined, taking human coding sequences as an example, and considerations of codon utilization and dinucleotide frequencies yield an overall homology of greater than 82%. Recommendations for probe design and hybridization are presented, and the choice between using multiple probes reflecting all codon possibilities and a unique optimal probe is discussed.

Dynamic, in vivo, real-time detection of retinal oxidative status in a model of elevated intraocular pressure using a novel, reversibly responsive, profluorescent nitroxide probe.

PubMed

Rayner, Cassie L; Gole, Glen A; Bottle, Steven E; Barnett, Nigel L

2014-12-01

Changes to the redox status of biological systems have been implicated in the pathogenesis of a wide variety of disorders including cancer, Ischemia-reperfusion (I/R) injury and neurodegeneration. In times of metabolic stress e.g. ischaemia/reperfusion, reactive oxygen species (ROS) production overwhelms the intrinsic antioxidant capacity of the cell, damaging vital cellular components. The ability to quantify ROS changes in vivo, is therefore essential to understanding their biological role. Here we evaluate the suitability of a novel reversible profluorescent probe containing a redox-sensitive nitroxide moiety (methyl ester tetraethylrhodamine nitroxide, ME-TRN), as an in vivo, real-time reporter of retinal oxidative status. The reversible nature of the probe's response offers the unique advantage of being able to monitor redox changes in both oxidizing and reducing directions in real time. After intravitreal administration of the ME-TRN probe, we induced ROS production in rat retina using an established model of complete, acute retinal ischaemia followed by reperfusion. After restoration of blood flow, retinas were imaged using a Micron III rodent fundus fluorescence imaging system, to quantify the redox-response of the probe. Fluorescent intensity declined during the first 60 min of reperfusion. The ROS-induced change in probe fluorescence was ameliorated with the retinal antioxidant, lutein. Fluorescence intensity in non-Ischemia eyes did not change significantly. This new probe and imaging technology provide a reversible and real-time response to oxidative changes and may allow the in vivo testing of antioxidant therapies of potential benefit to a range of diseases linked to oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

Breast imaging technology: Recent advances in imaging endogenous or transferred gene expression utilizing radionuclide technologies in living subjects - applications to breast cancer

PubMed Central

Berger, Frank; Sam Gambhir, Sanjiv

2001-01-01

A variety of imaging technologies is being investigated as tools for studying gene expression in living subjects. Two technologies that use radiolabeled isotopes are single photon emission computed tomography (SPECT) and positron emission tomography (PET). A relatively high sensitivity, a full quantitative tomographic capability, and the ability to extend small animal imaging assays directly into human applications characterize radionuclide approaches. Various radiolabeled probes (tracers) can be synthesized to target specific molecules present in breast cancer cells. These include antibodies or ligands to target cell surface receptors, substrates for intracellular enzymes, antisense oligodeoxynucleotide probes for targeting mRNA, probes for targeting intracellular receptors, and probes for genes transferred into the cell. We briefly discuss each of these imaging approaches and focus in detail on imaging reporter genes. In a PET reporter gene system for in vivo reporter gene imaging, the protein products of the reporter genes sequester positron emitting reporter probes. PET subsequently measures the PET reporter gene dependent sequestration of the PET reporter probe in living animals. We describe and review reporter gene approaches using the herpes simplex type 1 virus thymidine kinase and the dopamine type 2 receptor genes. Application of the reporter gene approach to animal models for breast cancer is discussed. Prospects for future applications of the transgene imaging technology in human gene therapy are also discussed. Both SPECT and PET provide unique opportunities to study animal models of breast cancer with direct application to human imaging. Continued development of new technology, probes and assays should help in the better understanding of basic breast cancer biology and in the improved management of breast cancer patients. PMID:11250742

Exploring the Neutrinoless Double Beta Decay in the Inverted Neutrino Hierarchy with Bolometric Detectors

DOE PAGES

Artusa, D. R.; Azzolini, O.; Balata, M.; ...

2014-10-15

Neutrinoless double beta decay (0νββ) is one of the most sensitive probes for physics beyond the Standard Model, providing unique information on the nature of neutrinos. In this paper we review the status and outlook for bolometric 0νββ decay searches. We summarize recent advances in background suppression demonstrated using bolometers with simultaneous readout of heat and light signals. We simulate several configurations of a future CUORE-like bolometer array which would utilize these improvements and present the sensitivity reach of a hypothetical next-generation bolometric0νββ experiment. We demonstrate that a bolometric experiment with the isotope mass of about 1 ton is capablemore » of reaching the sensitivity to the effective Majorana neutrino mass (|m ee|) of order 10-20 meV, thus completely exploring the so-called inverted neutrino mass hierarchy region. In conclusion, we highlight the main challenges and identify priorities for an R&D program addressing them.« less

Functionalized Gold Nanoparticles for the Detection of C-Reactive Protein

PubMed Central

António, Maria

2018-01-01

C-reactive protein (CRP) is a very important biomarker of infection and inflammation for a number of diseases. Routine CRP measurements with high sensitivity and reliability are highly relevant to the assessment of states of inflammation and the efficacy of treatment intervention, and require the development of very sensitive, selective, fast, robust and reproducible assays. Gold nanoparticles (Au NPs) are distinguished for their unique electrical and optical properties and the ability to conjugate with biomolecules. Au NP-based probes have attracted considerable attention in the last decade in the analysis of biological samples due to their simplicity, high sensitivity and selectivity. Thus, this article aims to be a critical and constructive analysis of the literature of the last three years regarding the advances made in the development of bioanalytical assays based on gold nanoparticles for the in vitro detection and quantification of C-reactive protein from biological samples. Current methods for Au NP synthesis and the strategies for surface modification aiming at selectivity towards CRP are highlighted. PMID:29597295

Clinical evaluation of the Jay Sensitivity Sensor Probe: a new microprocessor-controlled instrument to evaluate dentin hypersensitivity.

PubMed

Sowinski, Joseph A; Kakar, Ashish; Kakar, Kanupriya

2013-05-01

To compare the Jay Sensitivity Sensor Probe (Jay Probe), a new microprocessor-based, pre-calibrated instrument, with well accepted methods used to evaluate sensitivity, i.e. tactile response to the Yeaple Probe, air blast (Schiff scale), and patient responses by Visual Analog Score (VAS). Jay Probe assessments were accomplished using several approaches. With a cohort of 12 subjects, two clinical examiners compared the repeatability of the Jay and Yeaple Probes. A second evaluation of both probes was conducted during two independent parallel design clinical studies each enrolling 100 adults with dentin hypersensitivity (DH). In each study, subjects were evaluated for DH responses after twice daily oral hygiene with a negative control fluoride dentifrice or a positive control dentifrice formulated with ingredients proven to reduce sensitivity, i.e. potassium nitrate or 8.0% arginine with calcium carbonate. Tactile evaluations by the Jay and Yeaple Probes were conducted at baseline and recall visits over the 8-week duration of each study. Also evaluated at each visit were responses to air blast and to patient reported DH assessment by VAS. Low inter-examiner variability with no significant differences between replicate measurements (P > 0.05) was observed with the Jay Probe. Consistent with results from previous studies, subjects assigned dentifrices formulated with potassium nitrate or 8% arginine/calcium carbonate demonstrated improvements in Yeaple, air blast and VAS responses in comparison to those assigned the fluoride dentifrice (P < 0.05). Jay Probe responses correlated significantly with all other sensitivity measures (P < 0.05). Differences between these treatments were observed at all post-treatment evaluations using these methods.

Illuminating dark photons with high-energy colliders

NASA Astrophysics Data System (ADS)

Curtin, David; Essig, Rouven; Gori, Stefania; Shelton, Jessie

2015-02-01

High-energy colliders offer a unique sensitivity to dark photons, the mediators of a broken dark U(1) gauge theory that kinetically mixes with the Standard Model (SM) hypercharge. Dark photons can be detected in the exotic decay of the 125 GeV Higgs boson, h→ ZZ D →4 ℓ, and in Drell-Yan events, pp→ Z D → ℓℓ. If the dark U(1) is broken by a hidden-sector Higgs mechanism, then mixing between the dark and SM Higgs bosons also allows the exotic decay h → Z D Z D → 4 ℓ. We show that the 14 TeV LHC and a 100 TeV proton-proton collider provide powerful probes of both exotic Higgs decay channels. In the case of kinetic mixing alone, direct Drell-Yan production offers the best sensitivity to Z D , and can probe ɛ ≳ 9 × 10-4 (4 × 10-4) at the HL-LHC (100 TeV pp collider). The exotic Higgs decay h → ZZ D offers slightly weaker sensitivity, but both measurements are necessary to distinguish the kinetically mixed dark photon from other scenarios. If Higgs mixing is also present, then the decay h → Z D Z D can allow sensitivity to the Z D for ɛ ≳ 10-9 - 10-6 (10-10 - 10-7) for the mass range by searching for displaced dark photon decays. We also compare the Z D sensitivity at pp colliders to the indirect, but model-independent, sensitivity of global fits to electroweak precision observables. We perform a global electroweak fit of the dark photon model, substantially updating previous work in the literature. Electroweak precision measurements at LEP, Tevatron, and the LHC exclude ɛ as low as 3 × 10-2. Sensitivity can be improved by up to a factor of ˜ 2 with HL-LHC data, and an additional factor of ˜ 4 with ILC/GigaZ data.

MPAI (mass probes aided ionization) method for total analysis of biomolecules by mass spectrometry.

PubMed

Honda, Aki; Hayashi, Shinichiro; Hifumi, Hiroki; Honma, Yuya; Tanji, Noriyuki; Iwasawa, Naoko; Suzuki, Yoshio; Suzuki, Koji

2007-01-01

We have designed and synthesized various mass probes, which enable us to effectively ionize various molecules to be detected with mass spectrometry. We call the ionization method using mass probes the "MPAI (mass probes aided ionization)" method. We aim at the sensitive detection of various biological molecules, and also the detection of bio-molecules by a single mass spectrometry serially without changing the mechanical settings. Here, we review mass probes for small molecules with various functional groups and mass probes for proteins. Further, we introduce newly developed mass probes for proteins for highly sensitive detection.

Probing the onset of structural instabilities as a tool for detection of staling of dairy milk: A permittivity and conductivity study

NASA Astrophysics Data System (ADS)

Madhurima, V.; Harindran, Aswini

2018-05-01

Dairy milk is a worldwide drink and a versatile raw material for food industries too. The major issue regarding dairy milk is their contamination by micro-organisms and subsequent spoiling. Pasteurization and sealed packing are used to minimize this contamination. The presence of pathogenic micro-organisms like psychrotrophs, reduces the pH of fresh milk by fermenting the lactose into lactic acid leading to the spoiling of milk. While there are various tests to check the spoilage of milk, there is no unique test to detect the onset of the complex dynamics of spoilage. There have been some studies on the dielectric properties of dairy milk but the primary method of identification of freshness of milk is through the measurement of pH. In this study, broadband dielectric spectroscopy is used as a tool to probe the spoiling of milk and that provides the information about the structural changes of milk during spoilage. The gamma dispersion explains the influence of free water content which is found to be a sensitive tool to probe the onset of milk spoilage process. The observations here are further backed by studies on the particle size and zeta potential.

Accurate and fast creep test for viscoelastic fluids using disk-probe-type and quadrupole-arrangement-type electromagnetically spinning systems

NASA Astrophysics Data System (ADS)

Hirano, Taichi; Sakai, Keiji

2017-07-01

Viscoelasticity is a unique characteristic of soft materials and describes its dynamic response to mechanical stimulations. A creep test is an experimental method for measuring the strain ratio/rate against an applied stress, thereby assessing the viscoelasticity of the materials. We propose two advanced experimental systems suitable for the creep test, adopting our original electromagnetically spinning (EMS) technique. This technique can apply a constant torque by a noncontact mechanism, thereby allowing more sensitive and rapid measurements. The viscosity and elasticity of a semidilute wormlike micellar solution were determined using two setups, and the consistency between the results was assessed.

A ratiometric fluorescent probe for rapid and sensitive detection of biothiols in fetal bovine serum.

PubMed

Wang, Fengyang; Feng, Chongchong; Lu, Linlin; Xu, Zhiai; Zhang, Wen

2017-07-01

Herein, a ratiometric turn-on fluorescent probe for sensitive detection of biothiols was designed. The probe consisted of two parts: one was rhodamine B serving as a fluorescence reference, and the other was coumarin derivative as the responsive fluorophore with an acrylate group for biothiols recognition. The response was based on the mechanism of Michael addition and intramolecular cyclization reaction, and the probe showed ratiometric and sensitive response to biothiols. Especially, the detection limit of this probe for cysteine was found to be 0.13μΜ. More importantly, the probe showed the advantage of fast response, of which the fluorescence intensity can reach the maximum within 10min. The ratiometric fluorescent probe has been successfully applied for the determination of biothiols in fetal bovine serum samples and the result was in good agreement with that tested by Ellman method. Copyright © 2017. Published by Elsevier B.V.

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.

Recent advances in intracellular and in vivo ROS sensing: focus on nanoparticle and nanotube applications.

PubMed

Uusitalo, Larissa M; Hempel, Nadine

2012-01-01

Reactive oxygen species (ROS) are increasingly being implicated in the regulation of cellular signaling cascades. Intracellular ROS fluxes are associated with cellular function ranging from proliferation to cell death. Moreover, the importance of subtle, spatio-temporal shifts in ROS during localized cellular signaling events is being realized. Understanding the biochemical nature of the ROS involved will enhance our knowledge of redox-signaling. An ideal intracellular sensor should therefore resolve real-time, localized ROS changes, be highly sensitive to physiologically relevant shifts in ROS and provide specificity towards a particular molecule. For in vivo applications issues such as bioavailability of the probe, tissue penetrance of the signal and signal-to-noise ratio also need to be considered. In the past researchers have heavily relied on the use of ROS-sensitive fluorescent probes and, more recently, genetically engineered ROS sensors. However, there is a great need to improve on current methods to address the above issues. Recently, the field of molecular sensing and imaging has begun to take advantage of the unique physico-chemical properties of nanoparticles and nanotubes. Here we discuss the recent advances in the use of these nanostructures as alternative platforms for ROS sensing, with particular emphasis on intracellular and in vivo ROS detection and quantification.

Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer.

PubMed

Liu, Wei; Dai, Xing; Xie, Jian; Silver, Mark A; Zhang, Duo; Wang, Yanlong; Cai, Yawen; Diwu, Juan; Wang, Jian; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-07

The accurate detection of UV radiation is required in a wide range of chemical industries and environmental or biological related applications. Conventional methods taking advantage of semiconductor photodetectors suffer from several drawbacks such as sophisticated synthesis and manufacturing procedure, not being able to measure the accumulated UV dosage as well as high defect density in the material. Searching for new strategies or materials serving as precise UV dosage sensor with extremely low detection limit is still highly desirable. In this work, a radiation resistant uranium coordination polymer [UO 2 (L)(DMF)] (L = 5-nitroisophthalic acid, DMF = N,N-dimethylformamide, denoted as compound 1) was successfully synthesized through mild solvothermal method and investigated as a unique UV probe with the detection limit of 2.4 × 10 -7 J. On the basis of the UV dosage dependent luminescence spectra, EPR analysis, single crystal structure investigation, and the DFT calculation, the UV-induced radical quenching mechanism was confirmed. Importantly, the generated radicals are of significant stability which offers the opportunity for measuring the accumulated UV radiation dosage. Furthermore, the powder material of compound 1 was further upgraded into membrane material without loss in luminescence intensity to investigate the real application potentials. To the best of our knowledge, compound 1 represents the most sensitive coordination polymer based UV dosage probe reported to date.

Nanoparticle based bio-bar code technology for trace analysis of aflatoxin B1 in Chinese herbs.

PubMed

Yu, Yu-Yan; Chen, Yuan-Yuan; Gao, Xuan; Liu, Yuan-Yuan; Zhang, Hong-Yan; Wang, Tong-Ying

2018-04-01

A novel and sensitive assay for aflatoxin B1 (AFB1) detection has been developed by using bio-bar code assay (BCA). The method that relies on polyclonal antibodies encoded with DNA modified gold nanoparticle (NP) and monoclonal antibodies modified magnetic microparticle (MMP), and subsequent detection of amplified target in the form of bio-bar code using a fluorescent quantitative polymerase chain reaction (FQ-PCR) detection method. First, NP probes encoded with DNA that was unique to AFB1, MMP probes with monoclonal antibodies that bind AFB1 specifically were prepared. Then, the MMP-AFB1-NP sandwich compounds were acquired, dehybridization of the oligonucleotides on the nanoparticle surface allows the determination of the presence of AFB1 by identifying the oligonucleotide sequence released from the NP through FQ-PCR detection. The bio-bar code techniques system for detecting AFB1 was established, and the sensitivity limit was about 10 -8  ng/mL, comparable ELISA assays for detecting the same target, it showed that we can detect AFB1 at low attomolar levels with the bio-bar-code amplification approach. This is also the first demonstration of a bio-bar code type assay for the detection of AFB1 in Chinese herbs. Copyright © 2017. Published by Elsevier B.V.

A Redox-Nucleophilic Dual-Reactable Probe for Highly Selective and Sensitive Detection of H2S: Synthesis, Spectra and Bioimaging

NASA Astrophysics Data System (ADS)

Zhang, Changyu; Wang, Runyu; Cheng, Longhuai; Li, Bingjie; Xi, Zhen; Yi, Long

2016-07-01

Hydrogen sulfide (H2S) is an important signalling molecule with multiple biological functions. The reported H2S fluorescent probes are majorly based on redox or nucleophilic reactions. The combination usage of both redox and nucleophilic reactions could improve the probe’s selectivity, sensitivity and stability. Herein we report a new dual-reactable probe with yellow turn-on fluorescence for H2S detection. The sensing mechanism of the dual-reactable probe was based on thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine (a nucleophilic reaction) and reduction of azide to amine (a redox reaction). Compared with its corresponding single-reactable probes, the dual-reactable probe has higher selectivity and fluorescence turn-on fold with magnitude of multiplication from that of each single-reactable probe. The highly selective and sensitive properties enabled the dual-reactable probe as a useful tool for efficiently sensing H2S in aqueous buffer and in living cells.

Homogeneous versus heterogeneous probes for microbial ecological microarrays.

PubMed

Bae, Jin-Woo; Park, Yong-Ha

2006-07-01

Microbial ecological microarrays have been developed for investigating the composition and functions of microorganism communities in environmental niches. These arrays include microbial identification microarrays, which use oligonucleotides, gene fragments or microbial genomes as probes. In this article, the advantages and disadvantages of each type of probe are reviewed. Oligonucleotide probes are currently useful for probing uncultivated bacteria that are not amenable to gene fragment probing, whereas the functional gene fragments amplified randomly from microbial genomes require phylogenetic and hierarchical categorization before use as microbial identification probes, despite their high resolution for both specificity and sensitivity. Until more bacteria are sequenced and gene fragment probes are thoroughly validated, heterogeneous bacterial genome probes will provide a simple, sensitive and quantitative tool for exploring the ecosystem structure.

Tracing the conformational changes in BSA using FRET with environmentally-sensitive squaraine probes

NASA Astrophysics Data System (ADS)

Govor, Iryna V.; Tatarets, Anatoliy L.; Obukhova, Olena M.; Terpetschnig, Ewald A.; Gellerman, Gary; Patsenker, Leonid D.

2016-06-01

A new potential method of detecting the conformational changes in hydrophobic proteins such as bovine serum albumin (BSA) is introduced. The method is based on the change in the Förster resonance energy transfer (FRET) efficiency between protein-sensitive fluorescent probes. As compared to conventional FRET based methods, in this new approach the donor and acceptor dyes are not covalently linked to protein molecules. Performance of the new method is demonstrated using the protein-sensitive squaraine probes Square-634 (donor) and Square-685 (acceptor) to detect the urea-induced conformational changes of BSA. The FRET efficiency between these probes can be considered a more sensitive parameter to trace protein unfolding as compared to the changes in fluorescence intensity of each of these probes. Addition of urea followed by BSA unfolding causes a noticeable decrease in the emission intensities of these probes (factor of 5.6 for Square-634 and 3.0 for Square-685), and the FRET efficiency changes by a factor of up to 17. Compared to the conventional method the new approach therefore demonstrates to be a more sensitive way to detect the conformational changes in BSA.

Physics in ordered and disordered colloidal matter composed of poly(N-isopropylacrylamide) microgel particles.

PubMed

Yunker, Peter J; Chen, Ke; Gratale, Matthew D; Lohr, Matthew A; Still, Tim; Yodh, A G

2014-05-01

This review collects and describes experiments that employ colloidal suspensions to probe physics in ordered and disordered solids and related complex fluids. The unifying feature of this body of work is its clever usage of poly(N-isopropylacrylamide) (PNIPAM) microgel particles. These temperature-sensitive colloidal particles provide experimenters with a 'knob' for in situ control of particle size, particle interaction and particle packing fraction that, in turn, influence the structural and dynamical behavior of the complex fluids and solids. A brief summary of PNIPAM particle synthesis and properties is given, followed by a synopsis of current activity in the field. The latter discussion describes a variety of soft matter investigations including those that explore formation and melting of crystals and clusters, and those that probe structure, rearrangement and rheology of disordered (jammed/glassy) and partially ordered matter. The review, therefore, provides a snapshot of a broad range of physics phenomenology which benefits from the unique properties of responsive microgel particles.

Transient Astrophysics Probe

NASA Astrophysics Data System (ADS)

Camp, Jordan; Transient Astrophysics Probe Team

2018-01-01

The Transient Astrophysics Probe (TAP) is a wide-field multi-wavelength transient mission proposed for flight starting in the late 2020s. The mission instruments include unique “Lobster-eye” imaging soft X-ray optics that allow a ~1600 deg2 FoV; a high sensitivity, 1 deg2 FoV soft X-ray telescope; a 1 deg2 FoV Infrared telescope with bandpass 0.6-3 micron; and a set of 8 NaI gamma-ray detectors. TAP’s most exciting capability will be the observation of tens per year of X-ray and IR counterparts of GWs involving stellar mass black holes and neutron stars detected by LIGO/Virgo/KAGRA/LIGO-India, and possibly several per year X-ray counterparts of GWs from supermassive black holes, detected by LISA and Pulsar Timing Arrays. TAP will also discover hundreds of X-ray transients related to compact objects, including tidal disruption events, supernova shock breakouts, and Gamma-Ray Bursts from the epoch of reionization.

Invoking Direct Exciton-Plasmon Interactions by Catalytic Ag Deposition on Au Nanoparticles: Photoelectrochemical Bioanalysis with High Efficiency.

PubMed

Ma, Zheng-Yuan; Xu, Fei; Qin, Yu; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

2016-04-19

In this work, direct exciton-plasmon interactions (EPI) between CdS quantum dots (QDs) and Ag nanoparticles (NPs) were invoked ingeniously by catalytic Ag deposition on Au NPs for the stimulation of high efficient damping effect toward the excitonic responses in CdS QDs, on the basis of which a novel photoelectrochemical (PEC) bioanalytical format was achieved for sensitive microRNA detection. Specifically, upon the configurational change from the hairpin probe DNA to the "Y"-shaped ternary conjugate consisting of the original probe DNA, assistant DNA, and the target microRNA, the alkaline phosphatase (ALP) catalytic chemistry would then trigger the transition of the interparticle interplay from the CdS QDs-Au NPs to the CdS QDs-Ag NPs systems for the microRNA detection due to the dependence of the photocurrent quenching on the target concentration. This work not only provided a unique method for EPI generation among the PEC nanosystems but also offered a versatile and general protocol for future PEC bioanalysis development.

Opioid receptor probes derived from cycloaddition of the hallucinogen natural product salvinorin A.

PubMed

Lozama, Anthony; Cunningham, Christopher W; Caspers, Michael J; Douglas, Justin T; Dersch, Christina M; Rothman, Richard B; Prisinzano, Thomas E

2011-04-25

As part of our continuing efforts toward more fully understanding the structure-activity relationships of the neoclerodane diterpene salvinorin A, we report the synthesis and biological characterization of unique cycloadducts through [4+2] Diels-Alder cycloaddition. Microwave-assisted methods were developed and successfully employed, aiding in functionalizing the chemically sensitive salvinorin A scaffold. This demonstrates the first reported results for both cycloaddition of the furan ring and functionalization via microwave-assisted methodology of the salvinorin A skeleton. The cycloadducts yielded herein introduce electron-withdrawing substituents and bulky aromatic groups into the C-12 position. Kappa opioid (KOP) receptor space was explored through aromatization of the bent oxanorbornadiene system possessed by the cycloadducts to a planar phenyl ring system. Although dimethyl- and diethylcarboxylate analogues 5 and 6 retain some affinity and selectivity for KOP receptors and are full agonists, their aromatized counterparts 13 and 14 have reduced affinity for KOP receptors. The methods developed herein signify a novel approach toward rapidly probing the structure-activity relationships of furan-containing natural products.

Microbial identification by immunohybridization assay of artificial RNA labels

NASA Technical Reports Server (NTRS)

Kourentzi, Katerina D.; Fox, George E.; Willson, Richard C.

2002-01-01

Ribosomal RNA (rRNA) and engineered stable artificial RNAs (aRNAs) are frequently used to monitor bacteria in complex ecosystems. In this work, we describe a solid-phase immunocapture hybridization assay that can be used with low molecular weight RNA targets. A biotinylated DNA probe is efficiently hybridized in solution with the target RNA, and the DNA-RNA hybrids are captured on streptavidin-coated plates and quantified using a DNA-RNA heteroduplex-specific antibody conjugated to alkaline phosphatase. The assay was shown to be specific for both 5S rRNA and low molecular weight (LMW) artificial RNAs and highly sensitive, allowing detection of as little as 5.2 ng (0.15 pmol) in the case of 5S rRNA. Target RNAs were readily detected even in the presence of excess nontarget RNA. Detection using DNA probes as small as 17 bases targeting a repetitive artificial RNA sequence in an engineered RNA was more efficient than the detection of a unique sequence.

Mitochondrial NAD(P)H In vivo: Identifying Natural Indicators of Oxidative Phosphorylation in the (31)P Magnetic Resonance Spectrum.

PubMed

Conley, Kevin E; Ali, Amir S; Flores, Brandon; Jubrias, Sharon A; Shankland, Eric G

2016-01-01

Natural indicators provide intrinsic probes of metabolism, biogenesis and oxidative protection. Nicotinamide adenine dinucleotide metabolites (NAD(P)) are one class of indicators that have roles as co-factors in oxidative phosphorylation, glycolysis, and anti-oxidant protection, as well as signaling in the mitochondrial biogenesis pathway. These many roles are made possible by the distinct redox states (NAD(P)(+) and NAD(P)H), which are compartmentalized between cytosol and mitochondria. Here we provide evidence for detection of NAD(P)(+) and NAD(P)H in separate mitochondrial and cytosol pools in vivo in human tissue by phosphorus magnetic resonance spectroscopy ((31)P MRS). These NAD(P) pools are identified by chemical standards (NAD(+), NADP(+), and NADH) and by physiological tests. A unique resonance reflecting mitochondrial NAD(P)H is revealed by the changes elicited by elevation of mitochondrial oxidation. The decline of NAD(P)H with oxidation is matched by a stoichiometric rise in the NAD(P)(+) peak. This unique resonance also provides a measure of the improvement in mitochondrial oxidation that parallels the greater phosphorylation found after exercise training in these elderly subjects. The implication is that the dynamics of the mitochondrial NAD(P)H peak provides an intrinsic probe of the reversal of mitochondrial dysfunction in elderly muscle. Thus, non-invasive detection of NAD(P)(+) and NAD(P)H in cytosol vs. mitochondria yields natural indicators of redox compartmentalization and sensitive intrinsic probes of the improvement of mitochondrial function with an intervention in human tissues in vivo. These natural indicators hold the promise of providing mechanistic insight into metabolism and mitochondrial function in vivo in a range of tissues in health, disease and with treatment.

An Electrochemical Impedimetric Aptasensing Platform for Sensitive and Selective Detection of Small Molecules Such as Chloramphenicol

PubMed Central

Pilehvar, Sanaz; Dierckx, Tarryn; Blust, Ronny; Breugelmans, Tom; De Wael, Karolien

2014-01-01

We report on the aptadetection of chloramphenicol (CAP) using electrochemical impedance spectroscopy. The detection principle is based on the changes of the interfacial properties of the electrode after the interaction of the ssDNA aptamers with the target molecules. The electrode surface is partially blocked due to the formation of the aptamer-CAP complex, resulting in an increase of the interfacial electron-transfer resistance of the redox probe detected by electrochemical impedance spectroscopy or cyclic voltammetry. We observed that the ratio of polarization resistance had a linear relationship with the concentrations of CAP in the range of 1.76–127 nM, and a detection limit of 1.76 nM was obtained. The covalent binding of CAP-aptamer on the electrode surface combined with the unique properties of aptamers and impedimetric transduction leads to the development of a stable and sensitive electrochemical aptasensor for CAP. PMID:25004156

High sensitive THz superconducting hot electron bolometer mixers and transition edge sensors

NASA Astrophysics Data System (ADS)

Zhang, W.; Miao, W.; Zhou, K. M.; Guo, X. H.; Zhong, J. Q.; Shi, S. C.

2016-11-01

Terahertz band, which is roughly defined as 0.1 THz to 10 THz, is an interesting frequency region of the electromagnetic spectrum to be fully explored in astronomy. THz observations play key roles in astrophysics and cosmology. High sensitive heterodyne and direct detectors are the main tools for the detection of molecular spectral lines and fine atomic structure spectral lines, which are very important tracers for probing the physical and chemical properties and dynamic processes of objects such as star and planetary systems. China is planning to build an THz telescope at Dome A, Antarctica, a unique site for ground-based THz observations. We are developing THz superconducting hot electron bolometer (HEB) mixers and transition edge sensors (TES), which are quantum limited and back-ground limited detectors, respectively. Here we first introduce the working principles of superconducting HEB and TES, and then mainly present the results achieved at Purple mountain Observatory.

'Incremental thermocouple probe' for testing insulation erosion on a rocket motor

NASA Technical Reports Server (NTRS)

Gould, Reginald J.

1993-01-01

An incremental thermocouple probe was developed to measure insulation erosion during a solid rocket motor firing. The probe's new and unique design is described along with its theory of operation. Data from an actual firing are reported which show that the probe's performance greatly exceeded predictions and present technology as a temperature measurement device and as an event gage.

Target-protecting dumbbell molecular probe against exonucleases digestion for sensitive detection of ATP and streptavidin.

PubMed

Chen, Jinyang; Liu, Yucheng; Ji, Xinghu; He, Zhike

2016-09-15

In this work, a versatile dumbbell molecular (DM) probe was designed and employed in the sensitively homogeneous bioassay. In the presence of target molecule, the DM probe was protected from the digestion of exonucleases. Subsequently, the protected DM probe specifically bound to the intercalation dye and resulted in obvious fluorescence signal which was used to determine the target molecule in return. This design allows specific and versatile detection of diverse targets with easy operation and no sophisticated fluorescence labeling. Integrating the idea of target-protecting DM probe with adenosine triphosphate (ATP) involved ligation reaction, the DM probe with 5'-end phosphorylation was successfully constructed for ATP detection, and the limitation of detection was found to be 4.8 pM. Thanks to its excellent selectivity and sensitivity, this sensing strategy was used to detect ATP spiked in human serum as well as cellular ATP. Moreover, the proposed strategy was also applied in the visual detection of ATP in droplet-based microfluidic platform with satisfactory results. Similarly, combining the principle of target-protecting DM probe with streptavidin (SA)-biotin interaction, the DM probe with 3'-end biotinylation was developed for selective and sensitive SA determination, which demonstrated the robustness and versatility of this design. Copyright © 2016 Elsevier B.V. All rights reserved.

Long-wavelength analyte-sensitive luminescent probes and optical (bio)sensors

PubMed Central

Staudinger, Christoph; Borisov, Sergey M

2016-01-01

Long-wavelength luminescent probes and sensors become increasingly popular. They offer the advantage of lower levels of autofluorescence in most biological probes. Due to high penetration depth and low scattering of red and NIR light such probes potentially enable in vivo measurements in tissues and some of them have already reached a high level of reliability required for such applications. This review focuses on the recent progress in development and application of long-wavelength analyte-sensitive probes which can operate both reversibly and irreversibly. Photophysical properties, sensing mechanisms, advantages and limitations of individual probes are discussed. PMID:27134748

Novel fiber optic sensor probe with a pair of highly reflected connectors and a vessel of water absorption material for water leak detection.

PubMed

Cho, Tae-Sik; Choi, Ki-Sun; Seo, Dae-Cheol; Kwon, Il-Bum; Lee, Jung-Ryul

2012-01-01

The use of a fiber optic quasi-distributed sensing technique for detecting the location and severity of water leakage is suggested. A novel fiber optic sensor probe is devised with a vessel of water absorption material called as water combination soil (WCS) located between two highly reflected connectors: one is a reference connector and the other is a sensing connector. In this study, the sensing output is calculated from the reflected light signals of the two connectors. The first reflected light signal is a reference and the second is a sensing signal which is attenuated by the optical fiber bending loss due to the WCS expansion absorbing water. Also, the bending loss of each sensor probe is determined by referring to the total number of sensor probes and the total power budget of an entire system. We have investigated several probe characteristics to show the design feasibility of the novel fiber sensor probe. The effects of vessel sizes of the probes on the water detection sensitivity are studied. The largest vessel probe provides the highest sensitivity of 0.267 dB/mL, while the smallest shows relatively low sensitivity of 0.067 dB/mL, and unstable response. The sensor probe with a high output value provides a high sensitivity with various detection levels while the number of total installable sensor probes decreases.

Sonography of the chest using linear-array versus sector transducers: Correlation with auscultation, chest radiography, and computed tomography.

PubMed

Tasci, Ozlem; Hatipoglu, Osman Nuri; Cagli, Bekir; Ermis, Veli

2016-07-08

The primary purpose of our study was to compare the efficacies of two sonographic (US) probes, a high-frequency linear-array probe and a lower-frequency phased-array sector probe in the diagnosis of basic thoracic pathologies. The secondary purpose was to compare the diagnostic performance of thoracic US with auscultation and chest radiography (CXR) using thoracic CT as a gold standard. In total, 55 consecutive patients scheduled for thoracic CT were enrolled in this prospective study. Four pathologic entities were evaluated: pneumothorax, pleural effusion, consolidation, and interstitial syndrome. A portable US scanner was used with a 5-10-MHz linear-array probe and a 1-5-MHz phased-array sector probe. The first probe used was chosen randomly. US, CXR, and auscultation results were compared with the CT results. The linear-array probe had the highest performance in the identification of pneumothorax (83% sensitivity, 100% specificity, and 99% diagnostic accuracy) and pleural effusion (100% sensitivity, 97% specificity, and 98% diagnostic accuracy); the sector probe had the highest performance in the identification of consolidation (89% sensitivity, 100% specificity, and 95% diagnostic accuracy) and interstitial syndrome (94% sensitivity, 93% specificity, and 94% diagnostic accuracy). For all pathologies, the performance of US was superior to those of CXR and auscultation. The linear probe is superior to the sector probe for identifying pleural pathologies, whereas the sector probe is superior to the linear probe for identifying parenchymal pathologies. Thoracic US has better diagnostic performance than CXR and auscultation for the diagnosis of common pathologic conditions of the chest. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:383-389, 2016. © 2016 Wiley Periodicals, Inc.

Negative measurement sensitivity values of planar capacitive imaging probes

NASA Astrophysics Data System (ADS)

Yin, Xiaokang; Chen, Guoming; Li, Wei; Hutchins, David

2014-02-01

The measurement sensitivity distribution of planar capacitive imaging (CI) probes describes how effectively each region in the sensing area is contributing to the measured charge signal on the sensing electrode. It can be used to determine the imaging ability of a CI probe. It is found in previous work that, there are regions in the sensing area where the change of the charge output and the change of targeting physical parameter are of opposite trends. This opposite correlation implies that the measurement sensitivity values in such regions are negative. In this work, the cause of negative sensitivity is discussed. Experiments are also designed and performed so as to verify the existence of negative sensitivity and study the factors that may affect the negative sensitivity distributions.

Design of piezoelectric probe for measurement of longitudinal and shear components of elastic wave

NASA Astrophysics Data System (ADS)

Aoyanagi, Masafumi; Wakatsuki, Naoto; Mizutani, Koichi; Ebihara, Tadashi

2017-07-01

We focus on ultrasonic probes for nondestructive tests and evaluation. Transient characteristics of probes are important for nondestructive tests such as the pulse echo method. We previously reported the principle of measurement using a piezoelectric probe with triaxial sensitivities. In the results, it was calculated that the probe could transmit and receive particle displacement which contains normal and tangential components. It was confirmed that the probe had sensitivities in triaxial directions. However, its performance in terms of frequency and transient characteristics has not been evaluated. The purpose of this study is to design a probe by changing its shape to obtain better performance. The transient characteristics of probes in longitudinal and shear driving were evaluated by the inverse Fourier transformation of frequency responses of longitudinal and shear components, using the two-dimensional finite element method. As a result, the sensitivities at the dips of frequency characteristics increased when using our probe compared with those measured using conventional probes in longitudinal and shear driving. Hence, the performance in terms of the frequency response was improved by more than 3 dB under the conditions in this simulation. Also, the pulse width of impulse response was decreased by half compared with that of probes with conventional shapes.

Measuring small compartment dimensions by probing diffusion dynamics via Non-uniform Oscillating-Gradient Spin-Echo (NOGSE) NMR.

PubMed

Shemesh, Noam; Alvarez, Gonzalo A; Frydman, Lucio

2013-12-01

Noninvasive measurements of microstructure in materials, cells, and in biological tissues, constitute a unique capability of gradient-assisted NMR. Diffusion-diffraction MR approaches pioneered by Callaghan demonstrated this ability; Oscillating-Gradient Spin-Echo (OGSE) methodologies tackle the demanding gradient amplitudes required for observing diffraction patterns by utilizing constant-frequency oscillating gradient pairs that probe the diffusion spectrum, D(ω). Here we present a new class of diffusion MR experiments, termed Non-uniform Oscillating-Gradient Spin-Echo (NOGSE), which dynamically probe multiple frequencies of the diffusion spectral density at once, thus affording direct microstructural information on the compartment's dimension. The NOGSE methodology applies N constant-amplitude gradient oscillations; N-1 of these oscillations are spaced by a characteristic time x, followed by a single gradient oscillation characterized by a time y, such that the diffusion dynamics is probed while keeping (N-1)x+y≡TNOGSE constant. These constant-time, fixed-gradient-amplitude, multi-frequency attributes render NOGSE particularly useful for probing small compartment dimensions with relatively weak gradients - alleviating difficulties associated with probing D(ω) frequency-by-frequency or with varying relaxation weightings, as in other diffusion-monitoring experiments. Analytical descriptions of the NOGSE signal are given, and the sequence's ability to extract small compartment sizes with a sensitivity towards length to the sixth power, is demonstrated using a microstructural phantom. Excellent agreement between theory and experiments was evidenced even upon applying weak gradient amplitudes. An MR imaging version of NOGSE was also implemented in ex vivo pig spinal cords and mouse brains, affording maps based on compartment sizes. The effects of size distributions on NOGSE are also briefly analyzed. Copyright © 2013 Elsevier Inc. All rights reserved.

Sensitive determination of endogenous hydroxyl radical in live cell by a BODIPY based fluorescent probe.

PubMed

Lei, Kepeng; Sun, Mingtai; Du, Libo; Zhang, Xiaojie; Yu, Huan; Wang, Suhua; Hayat, Tasawar; Alsaedi, Ahmed

2017-08-01

The sensitive and selective fluorescence probe for hydroxyl radical analysis is of significance because hydroxyl radical plays key roles in many physiological and pathological processes. In this work, a novel organic fluorescence molecular probe OHP for hydroxyl radical is synthesized by a two-step route. The probe employs 4-bora-3a,4a-diaza-s-indacene (difluoroboron dipyrromethene, BODIPY) as the fluorophore and possesses relatively high fluorescence quantum yields (77.14%). Hydroxyl radical can rapidly react with the probe and quench the fluorescence in a good linear relationship (R 2 =0.9967). The limit of detection is determined to be as low as 11nM. In addition, it has been demonstrated that the probe has a good stability against pH and light illumination, low cytotoxicity and high biocompatibility. Cell culture experimental results show that the probe OHP is sensitive and selective for imaging and tracking endogenous hydroxyl radical in live cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Oligodeoxynucleotide Probes for Detecting Intact Cells

NASA Technical Reports Server (NTRS)

Rosson, Reinhardt A.; Maurina-Brunker, Julie; Langley, Kim; Pynnonen, Christine M.

2004-01-01

A rapid, sensitive test using chemiluminescent oligodeoxynucleotide probes has been developed for detecting, identifying, and enumerating intact cells. The test is intended especially for use in detecting and enumerating bacteria and yeasts in potable water. As in related tests that have been developed recently for similar purposes, the oligodeoxynucleotide probes used in this test are typically targeted at either singlecopy deoxyribonucleic acid (DNA) genes (such as virulence genes) or the multiple copies (10,000 to 50,000 copies per cell) of 16S ribosomal ribonucleic acids (rRNAs). Some of those tests involve radioisotope or fluorescent labeling of the probes for reporting hybridization of probes to target nucleic acids. Others of those tests involve labeling with enzymes plus the use of chemiluminescent or chromogenic substrates to report hybridization via color or the emission of light, respectively. The present test is of the last-mentioned type. The chemiluminescence in the present test can be detected easily with relatively simple instrumentation. In developing the present test, the hybridization approach was chosen because hybridization techniques are very specific. Hybridization detects stable, inheritable genetic targets within microorganisms. These targets are not dependent on products of gene expression that can vary with growth conditions or physiological states of organisms in test samples. Therefore, unique probes can be designed to detect and identify specific genera or species of bacteria or yeast (in terms of rRNA target sequences) or can be designed to detect and identify virulence genes (genomic target sequences). Because of the inherent specificity of this system, there are few problems of cross-reactivity. Hybridization tests are rapid, but hybridization tests now available commercially lack sensitivity; typically, between 10(exp 6) and 10(exp 7) cells of the target organism are needed to ensure a reliable test. Consequently, the numbers of target bacteria in samples are usually amplified by overnight pre-enrichment growth. These tests are usually performed in laboratories by skilled technicians. The present test was designed to overcome the shortcomings of the commercial hybridization tests. The figure summarizes the major steps of the test. It is important to emphasize that the hybridization process used in this test differs from that of other hybridization tests in that it does not extract target nucleic acids. This process is based on intact-cell hybridization (so-called in situ hybridization ), wherein the intact cells act as immobilizing agents. The cells are identified and enumerated by measuring the chemiluminescence emitted from alkaline phosphatase-probe (AP-probe) hybridization; the chemiluminescence is detected or measured by use of photographic film or a luminometer, respectively.

Enhancing the response rate of strand displacement-based electrochemical aptamer sensors using bivalent binding aptamer-cDNA probes.

PubMed

Zhang, Ziping; Tao, Cancan; Yin, Jungang; Wang, Yunhui; Li, Yanshen

2018-04-30

Electrochemical aptamer (EA) sensors based on aptamer-cDNA duplex probes (cDNA: complementary DNA) and target induced strand displacement (TISD) recognition are sensitive, selective and capable of detecting a wide variety of target analytes. While substantial research efforts have focused on engineering of new signaling mechanisms for the improvement of sensor sensitivity, little attention was paid to the enhancement of sensor response rate. Typically, the previous TISD based EA sensors exhibited relatively long response times larger than 30min, which mainly resulted from the suboptimal aptamer-cDNA probe structure in which most of aptamer bases were paired to the cDNA bases. In an effort to improve the response rate of this type of sensors, we report here the rational engineering of a quickly responsive and sensitive aptamer-cDNA probe by employing the conception of bivalent interaction in supramolecular chemistry. We design a bivalent cDNA strand through linking two short monovalent cDNA sequences, and it is simultaneously hybridized to two electrode-immobilized aptamer probes to form a bivalent binding (BB) aptamer-cDNA probe. This class of BB probe possesses the advantages of less aptamer bases paired to the cDNA bases for quick response rate and good structural stability for high sensor sensitivity. By use of the rationally designed BB aptamer-cDNA probe, a TISD based EA sensor against ATP with significantly enhanced response rate (with a displacement equilibrium time of 4min) and high sensitivity was successfully constructed. We believe that our BB probe conception will help guide future designs and applications of TISD based EA sensors. Copyright © 2017 Elsevier B.V. All rights reserved.

FRET-based small-molecule fluorescent probes: rational design and bioimaging applications.

PubMed

Yuan, Lin; Lin, Weiying; Zheng, Kaibo; Zhu, Sasa

2013-07-16

Fluorescence imaging has emerged as a powerful tool for monitoring biomolecules within the context of living systems with high spatial and temporal resolution. Researchers have constructed a large number of synthetic intensity-based fluorescent probes for bio-imaging. However, intensity-based fluorescent probes have some limitations: variations in probe concentration, probe environment, and excitation intensity may influence the fluorescence intensity measurements. In principle, the use of ratiometric fluorescent probes can alleviate this shortcoming. Förster resonance energy transfer (FRET) is one of the most widely used sensing mechanisms for ratiometric fluorescent probes. However, the development of synthetic FRET probes with favorable photophysical properties that are also suitable for biological imaging applications remains challenging. In this Account, we review the rational design and biological applications of synthetic FRET probes, focusing primarily on studies from our laboratory. To construct useful FRET probes, it is a pre-requisite to develop a FRET platform with favorable photophysical properties. The design criteria of a FRET platform include (1) well-resolved absorption spectra of the donor and acceptor, (2) well-separated emission spectra of the donor and acceptor, (3) donors and acceptors with comparable brightness, (4) rigid linkers, and (5) near-perfect efficiency in energy transfer. With an efficient FRET platform in hand, it is then necessary to modulate the donor-acceptor distance or spectral overlap integral in an analyte-dependent fashion for development of FRET probes. Herein, we emphasize our most recent progress on the development of FRET probes by spectral overlap integral, in particular by changing the molar absorption coefficient of the donor dyes such as rhodamine dyes, which undergo unique changes in the absorption profiles during the ring-opening and -closing processes. Although partial success has been obtained in design of first-generation rhodamine-based FRET probes via modulation of acceptor molar absorption coefficient, further improvements in terms of versatility, sensitivity, and synthetic accessibility are required. To address these issues with the first-generation rhodamine-based FRET probes, we have proposed a strategy for the design of second-generation probes. As a demonstration, we have developed FRET imaging probes for diverse targets including Cu²⁺, NO, HOCl, cysteine, and H₂O₂. This discussion of the methods for successfully designing synthetic FRET probes underscores the rational basis for further development of new FRET probes as a molecular toolbox for probing and manipulating a wide variety of biomolecules in living systems.

A novel near-infrared fluorescent probe for sensitive detection of β-galactosidase in living cells.

PubMed

Zhang, Jingtuo; Li, Cong; Dutta, Colina; Fang, Mingxi; Zhang, Shuwei; Tiwari, Ashutosh; Werner, Thomas; Luo, Fen-Tair; Liu, Haiying

2017-05-22

A novel near-infrared fluorescent probe for β-galactosidase has been developed based on a hemicyanine skeleton, which is conjugated with a d-galactose residue via a glycosidic bond. The probe serves as a substrate of β-galactosidase and displays rapid and sensitive turn-on fluorescent responses to β-galactosidase in aqueous solution. A 12.8-fold enhancement of fluorescence intensity at 703 nm was observed after incubation of 10 nM of β-galactosidase with 5 μM probe for 10 min. The probe can sensitively detect as little as 0.1 nM of β-galactosidase and shows linear responses to the enzyme concentration below 1.4 nM. The kinetic study showed that the probe has high binding affinity to β-galactosidase with K m  = 3.6 μM. The probe was used to detect β-galactosidase in living cells by employing the premature cell senescence model. The probe exhibited strong fluorescent signals in senescent cells but not in normal cells, which demonstrates that the probe is able to detect the endogenous senescence-associated β-galactosidase in living cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Selective chromo-fluorogenic detection of DFP (a Sarin and Soman mimic) and DCNP (a Tabun mimic) with a unique probe based on a boron dipyrromethene (BODIPY) dye.

PubMed

Barba-Bon, Andrea; Costero, Ana M; Gil, Salvador; Martínez-Máñez, Ramón; Sancenón, Félix

2014-11-21

A novel colorimetric probe (P4) for the selective differential detection of DFP (a Sarin and Soman mimic) and DCNP (a Tabun mimic) was prepared. Probe P4 contains three reactive sites; i.e. (i) a nucleophilic phenol group able to undergo phosphorylation with nerve gases, (ii) a carbonyl group as a reactive site for cyanide; and (iii) a triisopropylsilyl (TIPS) protecting group that is known to react with fluoride. The reaction of P4 with DCNP in acetonitrile resulted in both the phosphorylation of the phenoxy group and the release of cyanide, which was able to react with the carbonyl group of P4 to produce a colour modulation from pink to orange. In contrast, phosphorylation of P4 with DFP in acetonitrile released fluoride that hydrolysed the TIPS group in P4 to yield a colour change from pink to blue. Probe P4 was able to discriminate between DFP and DCNP with remarkable sensitivity; limits of detection of 0.36 and 0.40 ppm for DCNP and DFP, respectively, were calculated. Besides, no interference from other organophosphorous derivatives or with presence of acid was observed. The sensing behaviour of P4 was also retained when incorporated into silica gel plates or onto polyethylene oxide membranes, which allowed the development of simple test strips for the colorimetric detection of DCNP and DFP in the vapour phase. P4 is the first probe capable of colorimetrically differentiating between a Tabun mimic (DCNP) and a Sarin and Soman mimic (DFP).

Tissue-like Neural Probes for Understanding and Modulating the Brain.

PubMed

Hong, Guosong; Viveros, Robert D; Zwang, Theodore J; Yang, Xiao; Lieber, Charles M

2018-03-19

Electrophysiology tools have contributed substantially to understanding brain function, yet the capabilities of conventional electrophysiology probes have remained limited in key ways because of large structural and mechanical mismatches with respect to neural tissue. In this Perspective, we discuss how the general goal of probe design in biochemistry, that the probe or label have a minimal impact on the properties and function of the system being studied, can be realized by minimizing structural, mechanical, and topological differences between neural probes and brain tissue, thus leading to a new paradigm of tissue-like mesh electronics. The unique properties and capabilities of the tissue-like mesh electronics as well as future opportunities are summarized. First, we discuss the design of an ultraflexible and open mesh structure of electronics that is tissue-like and can be delivered in the brain via minimally invasive syringe injection like molecular and macromolecular pharmaceuticals. Second, we describe the unprecedented tissue healing without chronic immune response that leads to seamless three-dimensional integration with a natural distribution of neurons and other key cells through these tissue-like probes. These unique characteristics lead to unmatched stable long-term, multiplexed mapping and modulation of neural circuits at the single-neuron level on a year time scale. Last, we offer insights on several exciting future directions for the tissue-like electronics paradigm that capitalize on their unique properties to explore biochemical interactions and signaling in a "natural" brain environment.

Optically probing torsional superelasticity in spider silks

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

Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit

2013-11-11

We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-basedmore » materials and devices.« less

Multiplex detection of microRNAs by combining molecular beacon probes with T7 exonuclease-assisted cyclic amplification reaction.

PubMed

Liu, Yacui; Zhang, Jiangyan; Tian, Jingxiao; Fan, Xiaofei; Geng, Hao; Cheng, Yongqiang

2017-01-01

A simple, highly sensitive, and specific assay was developed for the homogeneous and multiplex detection of microRNAs (miRNAs) by combining molecular beacon (MB) probes and T7 exonuclease-assisted cyclic amplification. An MB probe with five base pairs in the stem region without special modification can effectively prevent the digestion by T7 exonuclease. Only in the presence of target miRNA is the MB probe hybridized with the target miRNA, and then digested by T7 exonuclease in the 5' to 3' direction. At the same time, the target miRNA is released and subsequently initiates the nuclease-assisted cyclic digestion process, generating enhanced fluorescence signal significantly. The results show that the combination of T7 exonuclease-assisted cyclic amplification reaction and MB probe possesses higher sensitivity for miRNA detection. Moreover, multiplex detection of miRNAs was successfully achieved by designing two MB probes labeled with FAM and Cy3, respectively. As a result, the method opens a new pathway for the sensitive and multiplex detection of miRNAs as well as clinical diagnosis. Graphical Abstract A simple, highly sensitive, and specific assay was developed for the detection of microRNAs by combining molecular beacon probes with T7 exonuclease-assisted cyclic amplification reaction.

Forbidden unique beta-decays and neutrino mass

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

Dvornický, Rastislav; Šimkovic, Fedor

2013-12-30

The measurement of the electron spectrum in beta-decays provides a robust direct determination of the values of neutrino masses. The planned rhenium beta-decay experiment, called the “Microcalorimeter Arrays for a Rhenium Experiment” (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which is expected to collect data in a near future. In this contribution we discuss the spectrum of emitted electrons close to the end point in the case of the first unique forbidden beta-decay of {sup 79}Se, {sup 107}Pd and {sup 187}Re. It is found that themore » p{sub 3/2}-wave emission dominates over the s{sub 1/2}-wave. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed beta-decay of {sup 3}H.« less

Analysis of non-contact and contact probe-to-sample thermal exchange for quantitative measurements of thin film and nanostructure thermal conductivity by the scanning hot probe method

NASA Astrophysics Data System (ADS)

Wilson, Adam A.

The ability to measure thermal properties of thin films and nanostructured materials is an important aspect of many fields of academic study. A strategy especially well-suited for nanoscale investigations of these properties is the scanning hot probe technique, which is unique in its ability to non-destructively interrogate the thermal properties with high resolution, both laterally as well as through the thickness of the material. Strategies to quantitatively determine sample thermal conductivity depend on probe calibration. State of the art calibration strategies assume that the area of thermal exchange between probe and sample does not vary with sample thermal conductivity. However, little investigation has gone into determining whether or not that assumption is valid. This dissertation provides a rigorous study into the probe-to-sample heat transfer through the air gap at diffusive distances for a variety of values of sample thermal conductivity. It is demonstrated that the thermal exchange radius and gap/contact thermal resistance varies with sample thermal conductivity as well as tip-to-sample clearance in non-contact mode. In contact mode, it is demonstrated that higher thermal conductivity samples lead to a reduction in thermal exchange radius for Wollaston probe tips. Conversely, in non-contact mode and in contact mode for sharper probe tips where air contributes the most to probe-to-sample heat transfer, the opposite trend occurs. This may be attributed to the relatively strong solid-to-solid conduction occurring between probe and sample for the Wollaston probes. A three-dimensional finite element (3DFE) model was developed to investigate how the calibrated thermal exchange parameters vary with sample thermal conductivity when calibrating the probe via the intersection method in non-contact mode at diffusive distances. The 3DFE model was then used to explore the limits of sensitivity of the experiment for a range of simulated experimental conditions. It is determined that, when operating the scanning hot probe technique in air at standard temperature and pressure using Wollaston probes, the technique is capable of measuring, within 20% uncertainty, samples with values of thermal conductivity up to 10 Wm-1K-1 in contact mode and up to 2 Wm-1K-1 in non-contact mode. By increasing the thermal conductivity of the probe's surroundings (i.e. changing air to a more conductive gas), sensitivity in non-contact mode to sample thermal conductivity is improved, which suggests potential for future investigations using non-contact scanning hot probe to measure thermal conductivity of higher thermal conductivity samples. The ability of the technique to differentiate thin films from the substrate is investigated, and the sensitivity of the technique to thin films and samples with anisotropic properties is explored. The models (both analytical and finite element) developed and reported in this dissertation lead to the ability to measure samples which, by the standard procedure before this work, were unable to be accurately measured. While other techniques failed to be able to successfully interrogate the film thermal conductivity of a full set of double-wall carbon nanotubes infused into polymers, the methods developed in this work allowed non-contact scanning hot probe measurements to be successfully performed to obtain the film thermal conductivity for each sample. Finite element simulations accounting for the anisotropy of these thin film on sample materials show similar trends with independently measured in-plane thermal conductivity for the only two (of five) samples in the set which were successfully able to be measured by the independent technique. Investigations in contact mode with high resolution Pd probes, whose probe-to-sample clearance is difficult to control in a repeatable fashion, show that surface roughness affects the thermal contact resistance. This can lead to values of reported sample thermal conductivity which are misleading, when using the standard calibrated thermal exchange parameters on samples with significantly different surface roughness than the calibration samples. This affect was taken into account to report sample thermal conductivity of Bi2Te3 nanoflakes.

Highly-sensitive microRNA detection based on bio-bar-code assay and catalytic hairpin assembly two-stage amplification.

PubMed

Tang, Songsong; Gu, Yuan; Lu, Huiting; Dong, Haifeng; Zhang, Kai; Dai, Wenhao; Meng, Xiangdan; Yang, Fan; Zhang, Xueji

2018-04-03

Herein, a highly-sensitive microRNA (miRNA) detection strategy was developed by combining bio-bar-code assay (BBA) with catalytic hairpin assembly (CHA). In the proposed system, two nanoprobes of magnetic nanoparticles functionalized with DNA probes (MNPs-DNA) and gold nanoparticles with numerous barcode DNA (AuNPs-DNA) were designed. In the presence of target miRNA, the MNP-DNA and AuNP-DNA hybridized with target miRNA to form a "sandwich" structure. After "sandwich" structures were separated from the solution by the magnetic field and dehybridized by high temperature, the barcode DNA sequences were released by dissolving AuNPs. The released barcode DNA sequences triggered the toehold strand displacement assembly of two hairpin probes, leading to recycle of barcode DNA sequences and producing numerous fluorescent CHA products for miRNA detection. Under the optimal experimental conditions, the proposed two-stage amplification system could sensitively detect target miRNA ranging from 10 pM to 10 aM with a limit of detection (LOD) down to 97.9 zM. It displayed good capability to discriminate single base and three bases mismatch due to the unique sandwich structure. Notably, it presented good feasibility for selective multiplexed detection of various combinations of synthetic miRNA sequences and miRNAs extracted from different cell lysates, which were in agreement with the traditional polymerase chain reaction analysis. The two-stage amplification strategy may be significant implication in the biological detection and clinical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Toward noninvasive detection and monitoring of malaria with broadband diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Campbell, Chris; Tromberg, Bruce J.; O'Sullivan, Thomas D.

2018-02-01

Despite numerous advances, malaria continues to kill nearly half a million people globally every year. New analytical methods and diagnostics are critical to understanding how treatments under development affect the lifecycle of malaria parasites. A biomarker that has been gaining interest is the "malaria pigment" hemozoin. This byproduct of hemoglobin digestion by the parasite has a unique spectral signature but is difficult to differentiate from hemoglobin and other tissue chromophores. Hemozoin can be detected in blood samples, but only utilizing approaches that require specialized training and facilities. Diffuse optical spectroscopy (DOS) is a noninvasive sensing technique that is sensitive to near-infrared absorption and scattering and capable of probing centimeter-deep volumes of tissue in vivo. DOS is relatively low-cost, does not require specialized training and thus potentially suitable for use in low-resource settings. In this work, we assess the potential of DOS to detect and quantify the presence of hemozoin noninvasively and at physiologically relevant levels. We suspended synthetic hemozoin in Intralipid-based tissue-simulating phantoms in order to mimic malaria infection in multiply-scattering tissue. Using a fiber probe that combines frequency-domain and continuous-wave broadband DOS (650-1000 nm), we detected hemozoin concentrations below 250 ng/ml, which corresponds to parasitemia sensitivities comparable to modern rapid diagnostic tests. We used the experimental variability to simulate and estimate the sensitivity of DOS to hemozoin in tissue that includes hemoglobin, water, and lipid under various tissue oxygen saturation levels. The results indicate that with increased precision, it may be possible to detect Hz noninvasively with DOS.

Understanding Atom Probe Tomography of Oxide-Supported Metal Nanoparticles by Correlation with Atomic Resolution Electron Microscopy and Field Evaporation Simulation

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

Devaraj, Arun; Colby, Robert J.; Vurpillot, F.

2014-03-26

Metal-dielectric composite materials, specifically metal nanoparticles supported on or embedded in metal oxides, are widely used in catalysis. The accurate optimization of such nanostructures warrants the need for detailed three-dimensional characterization. Atom probe tomography is uniquely capable of generating sub-nanometer structural and compositional data with part-per-million mass sensitivity, but there are reconstruction artifacts for composites containing materials with strongly differing fields of evaporation, as for oxide-supported metal nanoparticles. By correlating atom probe tomography with scanning transmission electron microscopy for Au nanoparticles embedded in an MgO support, deviations from an ideal topography during evaporation are demonstrated directly, and correlated with compositionalmore » errors in the reconstructed data. Finite element simulations of the field evaporation process confirm that protruding Au nanoparticles will evolve on the tip surface, and that evaporation field variations lead to an inaccurate assessment of the local composition, effectively lowering the spatial resolution of the final reconstructed dataset. Cross-correlating the experimental data with simulations results in a more detailed understanding of local evaporation aberrations during APT analysis of metal-oxide composites, paving the way towards a more accurate three-dimensional characterization of this technologically important class of materials.« less

Radioimmunoguided surgery using iodine 125 B72. 3 in patients with colorectal cancer

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

Cohen, A.M.; Martin, E.W. Jr.; Lavery, I.

1991-03-01

Preliminary data using B72.3 murine monoclonal antibody labeled with iodine 125 suggested that both clinically apparent as well as occult sites of colorectal cancer could be identified intraoperatively using a hand-held gamma detecting probe. We report the preliminary data of a multicenter trial of this approach in patients with primary or recurrent colorectal cancer. One hundred four patients with primary, suspected, or known recurrent colorectal cancer received an intravenous infusion of 1 mg of B72.3 monoclonal antibody radiolabeled with 7.4 x 10 Bq of iodine 125. Twenty-six patients with primary colorectal cancer and 72 patients with recurrent colorectal cancer weremore » examined. Using the gamma detecting probe, 78% of the patients had localization of the antibody in their tumor; this included 75% of primary tumor sites and 63% of all recurrent tumor sites; 9.2% of all tumor sites identified represented occult sites detected only with the gamma detecting probe. The overall sensitivity was 77% and a predictive value of a positive detection was 78%. A total of 30 occult sites in 26 patients were identified. In patients with recurrent cancer, the antibody study provided unique data that precluded resection in 10 patients, and in another eight patients it extended the potentially curative procedure.« less

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.

Publications - GMC 414 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 414 Publication Details Title: Sensitive High Resolution Ion Micro Probe (SHRIMP) data of Gottlieb, E., 2012, Sensitive High Resolution Ion Micro Probe (SHRIMP) data of outcrop samples from the

A high sensitivity MEA probe for measuring real time rat brain glucose flux.

PubMed

Wei, Wenjing; Song, Yilin; Shi, Wentao; Lin, Nansen; Jiang, Tingjun; Cai, Xinxia

2014-05-15

The mammalian central nervous system (CNS) relies on a constant supply of external glucose for its undisturbed operation. This article presents an implantable Multi-Electrode Array (MEA) probe for brain glucose measurement. The MEA was implemented on Silicon-On-Insulator (SOI) wafer using Micro-Electro-Mechanical-Systems (MEMS) methods. There were 16 platinum recording sites on the probe and enzyme glucose oxidase (GOx) was immobilized on them. The glucose sensitivity of the MEA probe was as high as 489 µA mM(-1) cm(-2). 1,3-Phenylenediamine (mPD) was electropolymerized onto the Pt recording surfaces to prevent larger molecules such as ascorbic acid (AA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), and dopamine (DA) from reaching the recording sites surface. The MEA probe was implanted in the anesthetized rat striatum and responded to glucose levels which were altered by intraperitoneal injection of glucose and insulin. After the in vivo experiment, the MEA probe still kept sensitivity to glucose, these suggested that the MEA probe was reliable for glucose monitoring in brain extracellular fluid (ECF). © 2013 Published by Elsevier B.V.

Neurotransmitter measurement with a fiber optic probe using pulsed ultraviolet resonance Raman spectroscopy

NASA Astrophysics Data System (ADS)

Schulze, H. Georg; Greek, L. Shane; Blades, Michael W.; Bree, Alan V.; Gorzalka, Boris B.; Turner, Robin F. B.

1997-05-01

Many techniques have been developed to investigate the chemistry associated with brain activity. These techniques generally fall into two categories: fast techniques with species restricted sensitivity and slow techniques with generally unrestricted species sensitivity. Therefore, a need exists for a fast non-invasive technique sensitive to a wide array of biologically relevant compounds in order to measure chemical brain events in real time. The work presented here describes the progress made toward the development of a novel neurotransmitter probe. A fiber-optic linked Raman and tunable ultraviolet resonance Raman system was assembled with custom designed optical fiber probes. Probes of several different geometries were constructed and their working curves obtained in aqueous mixtures of methyl orange and potassium nitrate to determine the best probe configuration given particular sample characteristics. Using this system, the ultraviolet resonance Raman spectra of some neurotransmitters were measured with a fiber-optic probe and are reported here for the first time. The probe has also been used to measure neurotransmitter secretions obtained from depolarized rat pheochromocytoma cells.

Assembling a prototype resonance electrical impedance spectroscopy system for breast tissue signal detection: preliminary assessment

NASA Astrophysics Data System (ADS)

Sumkin, Jules; Zheng, Bin; Gruss, Michelle; Drescher, John; Leader, Joseph; Good, Walter; Lu, Amy; Cohen, Cathy; Shah, Ratan; Zuley, Margarita; Gur, David

2008-03-01

Using electrical impedance spectroscopy (EIS) technology to detect breast abnormalities in general and cancer in particular has been attracting research interests for decades. Large clinical tests suggest that current EIS systems can achieve high specificity (>= 90%) at a relatively low sensitivity ranging from 15% to 35%. In this study, we explore a new resonance frequency based electrical impedance spectroscopy (REIS) technology to measure breast tissue EIS signals in vivo, which aims to be more sensitive to small tissue changes. Through collaboration between our imaging research group and a commercial company, a unique prototype REIS system has been assembled and preliminary signal acquisition has commenced. This REIS system has two detection probes mounted in the two ends of a Y-shape support device with probe separation of 60 mm. During REIS measurement, one probe touches the nipple and the other touches to an outer point of the breast. The electronic system continuously generates sweeps of multi-frequency electrical pulses ranging from 100 to 4100 kHz. The maximum electric voltage and the current applied to the probes are 1.5V and 30mA, respectively. Once a "record" command is entered, multi-frequency sweeps are recorded every 12 seconds until the program receives a "stop recording" command. In our imaging center, we have collected REIS measurements from 150 women under an IRB approved protocol. The database includes 58 biopsy cases, 78 screening negative cases, and other "recalled" cases (for additional imaging procedures). We measured eight signal features from the effective REIS sweep of each breast. We applied a multi-feature based artificial neural network (ANN) to classify between "biopsy" and normal "non-biopsy" breasts. The ANN performance is evaluated using a leave-one-out validation method and ROC analysis. We conducted two experiments. The first experiment attempted to classify 58 "biopsy" breasts and 58 "non-biopsy" breasts acquired on 58 women each having one breast recommended for biopsy. The second experiment attempted to classify 58 "biopsy" breasts and 58 negative breasts from the set of screening negative cases. The areas under ROC curves are 0.679 +/- 0.033 and 0.606 +/- 0.035 for the first and the second experiment, respectively. The preliminary results demonstrate (1) even with this rudimentary system with only one paired probes there is a measurable signal of changes in breast tissue demonstrating the feasibility of applying REIS technology for identifying at least some women with highly suspicious breast abnormalities and (2) the electromagnetic asymmetry between two breasts may be more sensitive in detecting changes in the abnormal breast. To further improve the REIS system performance, we are currently designing a new REIS system with multiple electrical probes and a more sophisticated analysis scheme.

Target-specific nanoparticles containing a broad band emissive NIR dye for the sensitive detection and characterization of tumor development.

PubMed

Behnke, Thomas; Mathejczyk, Julia E; Brehm, Robert; Würth, Christian; Gomes, Fernanda Ramos; Dullin, Christian; Napp, Joanna; Alves, Frauke; Resch-Genger, Ute

2013-01-01

Current optical probes including engineered nanoparticles (NPs) are constructed from near infrared (NIR)-emissive organic dyes with narrow absorption and emission bands and small Stokes shifts prone to aggregation-induced self-quenching. Here, we present the new asymmetric cyanine Itrybe with broad, almost environment-insensitive absorption and emission bands in the diagnostic window, offering a unique flexibility of the choice of excitation and detection wavelengths compared to common NIR dyes. This strongly emissive dye was spectroscopically studied in different solvents and encapsulated into differently sized (15, 25, 100 nm) amino-modified polystyrene NPs (PSNPs) via a one-step staining procedure. As proof-of-concept for its potential for pre-/clinical imaging applications, Itrybe-loaded NPs were surface-functionalized with polyethylene glycol (PEG) and the tumor-targeting antibody Herceptin and their binding specificity to the tumor-specific biomarker HER2 was systematically assessed. Itrybe-loaded NPs display strong fluorescence signals in vitro and in vivo and Herceptin-conjugated NPs bind specifically to HER2 as demonstrated in immunoassays as well as on tumor cells and sections from mouse tumor xenografts in vitro. This demonstrates that our design strategy exploiting broad band-absorbing and -emitting dyes yields versatile and bright NIR probes with a high potential for e.g. the sensitive detection and characterization of tumor development and progression. Copyright © 2012 Elsevier Ltd. All rights reserved.

ngVLA Key Science Goal 2: Probing the Initial Conditions for Planetary Systems and Life with Astrochemistry

NASA Astrophysics Data System (ADS)

McGuire, Brett; ngVLA Science Working Group 1

2018-01-01

One of the most challenging aspects in understanding the origin and evolution of planets and planetary systems is tracing the influence of chemistry on the physical evolution of a system from a molecular cloud to a solar system. Existing facilities have already shown the stunning degree of molecular complexity present in these systems. The unique combination of sensitivity and spatial resolution offered by the ngVLA will permit the observation of both highly complex and very low-abundance chemical species that are exquisitely sensitive to the physical conditions and evolutionary history of their sources, which are out of reach of current observatories. In turn, by understanding the chemical evolution of these complex molecules, unprecedentedly detailed astrophysical insight can be gleaned from these astrochemical observations.This poster will overview a number of key science goals in astrochemistry which will be enabled by the ngVLA, including:1) imaging of the deepest, densest regions in protoplanetary disks and unveiling the physical history through isotopic ratios2) probing the ammonia snow line in these disks, thought to be the only viable tracer of the water snowline3) observations of the molecular content of giant planet atmospheres4) detections of new, complex molecules, potentially including the simplest amino acids and sugars5) tracing the origin of chiral excess in star-forming regions

Rapid visual detection of cyprinid herpesvirus 2 by recombinase polymerase amplification combined with a lateral flow dipstick.

PubMed

Wang, H; Sun, M; Xu, D; Podok, P; Xie, J; Jiang, Ys; Lu, Lq

2018-05-28

Herpesviral haematopoietic necrosis (HVHN), caused by cyprinid herpesvirus 2 (CyHV-2), causes significant losses in crucian carp (Carassius carassius) aquaculture. Rapid and convenient DNA assay detection of CyHV-2 is useful for field diagnosis. Recombinase polymerase amplification (RPA) is a novel isothermal DNA amplification and detection technology that can amplify DNA within 30 min at ~37°C by simulating in vivo DNA recombination. Herein, a rapid and convenient detection assay based on RPA with a lateral flow dipstick (LFD) was developed for detecting CyHV-2. The highly conserved ORF72 of CyHV-2 was targeted by specific and sensitive primers and probes. The optimized assay takes only 15 min at 38°C using a water bath, with analysis of products by 2% agarose gel electrophoresis within 30 min. A simple lateral flow strip based on the unique probe in reaction buffer was developed for visualization. The entire RPA-LFD assay takes 50 min less than the routine PCR method, is 100 times more sensitive and displays no cross-reaction with other aquatic viruses. The combined isothermal RPA and lateral flow assay (RPA-LFD) provides a simple, rapid, reliable method that could improve field diagnosis of CyHV-2 when resources are limited. © 2018 John Wiley & Sons Ltd.

Toehold-mediated strand displacement reaction-dependent fluorescent strategy for sensitive detection of uracil-DNA glycosylase activity.

PubMed

Wu, Yushu; Wang, Lei; Jiang, Wei

2017-03-15

Sensitive detection of uracil-DNA glycosylase (UDG) activity is beneficial for evaluating the repairing process of DNA lesions. Here, toehold-mediated strand displacement reaction (TSDR)-dependent fluorescent strategy was constructed for sensitive detection of UDG activity. A single-stranded DNA (ssDNA) probe with two uracil bases and a trigger sequence were designed. A hairpin probe with toehold domain was designed, and a reporter probe was also designed. Under the action of UDG, two uracil bases were removed from ssDNA probe, generating apurinic/apyrimidinic (AP) sites. Then, the AP sites could inhibit the TSDR between ssDNA probe and hairpin probe, leaving the trigger sequence in ssDNA probe still free. Subsequently, the trigger sequence was annealed with the reporter probe, initiating the polymerization and nicking amplification reaction. As a result, numerous G-quadruplex (G4) structures were formed, which could bind with N-methyl-mesoporphyrin IX (NMM) to generate enhanced fluorescent signal. In the absence of UDG, the ssDNA probe could hybridize with the toehold domain of the hairpin probe to initiate TSDR, blocking the trigger sequence, and then the subsequent amplification reaction would not occur. The proposed strategy was successfully implemented for detecting UDG activity with a detection limit of 2.7×10 -5 U/mL. Moreover, the strategy could distinguish UDG well from other interference enzymes. Furthermore, the strategy was also applied for detecting UDG activity in HeLa cells lysate with low effect of cellular components. These results indicated that the proposed strategy offered a promising tool for sensitive quantification of UDG activity in UDG-related function study and disease prognosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Salience network response to changes in emotional expressions of others is heightened during early adolescence: relevance for social functioning.

PubMed

Rosen, Maya L; Sheridan, Margaret A; Sambrook, Kelly A; Dennison, Meg J; Jenness, Jessica L; Askren, Mary K; Meltzoff, Andrew N; McLaughlin, Katie A

2018-05-01

Adolescence is a unique developmental period when the salience of social and emotional information becomes particularly pronounced. Although this increased sensitivity to social and emotional information has frequently been considered with respect to risk behaviors and psychopathology, evidence suggests that increased adolescent sensitivity to social and emotional cues may confer advantages. For example, greater sensitivity to shifts in the emotions of others is likely to promote flexible and adaptive social behavior. In this study, a sample of 54 children and adolescents (age 8-19 years) performed a delayed match-to-sample task for emotional faces while undergoing fMRI scanning. Recruitment of the anterior cingulate and anterior insula when the emotion of the probe face did not match the emotion held in memory followed a quadratic developmental pattern that peaked during early adolescence. These findings indicate meaningful developmental variation in the neural mechanisms underlying sensitivity to changes in the emotional expressions. Across all participants, greater activation of this network for changes in emotional expression was associated with less social anxiety and fewer social problems. These results suggest that the heightened salience of social and emotional information during adolescence may confer important advantages for social behavior, providing sensitivity to others' emotions that facilitates flexible social responding. © 2017 John Wiley & Sons Ltd.

Ratiometric Time-Gated Luminescence Probe for Nitric Oxide Based on an Apoferritin-Assembled Lanthanide Complex-Rhodamine Luminescence Resonance Energy Transfer System.

PubMed

Tian, Lu; Dai, Zhichao; Liu, Xiangli; Song, Bo; Ye, Zhiqiang; Yuan, Jingli

2015-11-03

Using apoferritin (AFt) as a carrier, a novel ratiometric luminescence probe based on luminescence resonance energy transfer (LRET) between a Tb(3+) complex (PTTA-Tb(3+)) and a rhodamine derivative (Rh-NO), PTTA-Tb(3+)@AFt-Rh-NO, has been designed and prepared for the specific recognition and time-gated luminescence detection of nitric oxide (NO) in living samples. In this LRET probe, PTTA-Tb(3+) encapsulated in the core of AFt is the energy donor, and Rh-NO, a NO-responsive rhodamine derivative, bound on the surface of AFt is the energy acceptor. The probe only emits strong Tb(3+) luminescence because the emission of rhodamine is switched off in the absence of NO. Upon reaction with NO, accompanied by the turn-on of rhodamine emission, the LRET from Tb(3+) complex to rhodamine occurs, which results in the remarkable increase and decrease of the long-lived emissions of rhodamine and PTTA-Tb(3+), respectively. After the reaction, the intensity ratio of rhodamine emission to Tb(3+) emission, I565/I539, is ∼24.5-fold increased, and the dose-dependent enhancement of I565/I539 shows a good linearity in a wide concentration range of NO. This unique luminescence response allowed PTTA-Tb(3+)@AFt-Rh-NO to be conveniently used as a ratiometric probe for the time-gated luminescence detection of NO with I565/I539 as a signal. Taking advantages of high specificity and sensitivity of the probe as well as its good water-solubility, biocompatibility, and cell membrane permeability, PTTA-Tb(3+)@AFt-Rh-NO was successfully used for the luminescent imaging of NO in living cells and Daphnia magna. The results demonstrated the efficacy of the probe and highlighted it's advantages for the ratiometric time-gated luminescence bioimaging application.

ngVLA Key Science Goal 4: Using Pulsars in the Galactic Center as Fundamental Tests of Gravity

NASA Astrophysics Data System (ADS)

Bower, Geoffrey C.; Chatterjee, Shami; Cordes, James; Demorest, Paul; Dexter, Jason; Kramer, Michael; Lazio, Joseph; Ransom, Scott; Wharton, Robert; ngVLA Science Working Group 4

2018-01-01

Pulsars in the Galactic Center (GC) are important probes of general relativity (GR), star formation, stellar dynamics, stellar evolution, and the interstellar medium. A pulsar in orbit around the massive black hole in the GC, Sgr A*, has the power to provide a high-precision measurement of the black hole mass and spin in a unique regime of GR. It is sufficient to find and time a normal, slowly rotating pulsar in a reasonable orbit, in order to measure the mass of Sgr A* with a precision of 1 solar mass, to test the cosmic censorship conjecture to a precision of 0.1%, and to test the no-hair theorem to a precision of 1%. The pulsar population in the GC on scales from the inner parsec to the edge of the Central Molecular Zone (250 parsecs in diameter) can provide fresh insight into the complex processes at work in this region: the characteristic age distribution of the discovered pulsars will give insight into the star formation history; millisecond pulsars can be used as acceleratormeters to probe the local gravitational potential; the observed dispersion and scattering measures (and their variability) will allow us to probe the distribution, clumpiness and other properties of the central interstellar medium, including characterization of the central magnetic field using Faraday rotation. Proper motions of young pulsars can be used to point back to regions of recent star formation and/or supernova remnants.Despite years of searching, only a handful of pulsars in the central 0.5 degrees are known. This is likely the result of strong interstellar scattering along the line of sight, which broadens individual pulses to greater width than the pulse period. Scattering effects decline as wavelength to the fourth power, implying that we require observation at higher frequencies than are typical for typical pulsar searches. The characteristic steep spectrum of pulsars, however, implies the need for greater instrumental sensitivity at higher frequencies in order to detect and monitor pulsars. The ngVLA with its enhanced sensitivity at radio frequencies between 10 and 30 GHz will be unique in its capability to open a new door for the study of pulsars in the GC.

Sensitive fluorescence on-off probes for the fast detection of a chemical warfare agent mimic.

PubMed

Khan, Muhammad Shar Jhahan; Wang, Ya-Wen; Senge, Mathias O; Peng, Yu

2018-01-15

Two highly sensitive probes bearing a nucleophilic imine moiety have been utilized for the selective detection of chemical warfare agent (CWA) mimics. Diethyl chlorophosphate (DCP) was used as mimic CWAs. Both iminocoumarin-benzothiazole-based probes not only demonstrated a remarkable fluorescence ON-OFF response and good recognition, but also exhibited fast response times (10s) along with color changes upon addition of DCP. Limits of detection for the two sensors 1 and 2 were calculated as 0.065μM and 0.21μM, respectively, which are much lower than most other reported probes. These two probes not only show high sensitivity and selectivity in solution, but can also be applied for the recognition of DCP in the gas state, with significant color changes easily observed by the naked eye. Copyright © 2017 Elsevier B.V. All rights reserved.

Probing 6D operators at future e - e + colliders

NASA Astrophysics Data System (ADS)

Chiu, Wen Han; Leung, Sze Ching; Liu, Tao; Lyu, Kun-Feng; Wang, Lian-Tao

2018-05-01

We explore the sensitivities at future e - e + colliders to probe a set of six-dimensional operators which can modify the SM predictions on Higgs physics and electroweak precision measurements. We consider the case in which the operators are turned on simultaneously. Such an analysis yields a "conservative" interpretation on the collider sensitivities, complementary to the "optimistic" scenario where the operators are individually probed. After a detail analysis at CEPC in both "conservative" and "optimistic" scenarios, we also considered the sensitivities for FCC-ee and ILC. As an illustration of the potential of constraining new physics models, we applied sensitivity analysis to two benchmarks: holographic composite Higgs model and littlest Higgs model.

A compact, high temperature nuclear magnetic resonance probe for use in a narrow-bore superconducting magnet

NASA Astrophysics Data System (ADS)

Adler, Stuart B.; Michaels, James N.; Reimer, Jeffrey A.

1990-11-01

The design of a nuclear magnetic resonance (NMR) probe is reported, that can be used in narrow-bore superconducting solenoids for the observation of nuclear induction at high temperatures. The probe is compact, highly sensitive, and stable in continuous operation at temperatures up to 1050 C. The essential feature of the probe is a water-cooled NMR coil that contains the sample-furnace; this design maximizes sensitivity and circuit stability by maintaining the probe electronics at ambient temperature. The design is demonstrated by showing high temperature O-17 NMR spectra and relaxation measurements in solid barium bismuth oxide and yttria-stabilized zirconia.

Use of synthetic oligonucleotide DNA probes for the identification of Bacteroides gingivalis.

PubMed Central

Moncla, B J; Braham, P; Dix, K; Watanabe, S; Schwartz, D

1990-01-01

Six different oligonucleotide probes complementary to the hypervariable regions of 16S rRNA of Bacteroides gingivalis were tested for specificity and sensitivity against 77 field strains of B. gingivalis and 105 strains of 12 other Bacteroides species. The data demonstrated that these probes were very specific (range, 0.85 to 1.00) and sensitive (1.00). Some limited cross-reactions with other Bacteroides species were observed. Four of these probes should be useful for rapid detection and identification of B. gingivalis. Images PMID:1690217

Nanoparticles for cancer imaging: The good, the bad, and the promise

PubMed Central

Chapman, Sandra; Dobrovolskaia, Marina; Farahani, Keyvan; Goodwin, Andrew; Joshi, Amit; Lee, Hakho; Meade, Thomas; Pomper, Martin; Ptak, Krzysztof; Rao, Jianghong; Singh, Ravi; Sridhar, Srinivas; Stern, Stephan; Wang, Andrew; Weaver, John B.; Woloschak, Gayle; Yang, Lily

2014-01-01

Summary Recent advances in molecular imaging and nanotechnology are providing new opportunities for biomedical imaging with great promise for the development of novel imaging agents. The unique optical, magnetic, and chemical properties of materials at the scale of nanometers allow the creation of imaging probes with better contrast enhancement, increased sensitivity, controlled biodistribution, better spatial and temporal information, multi-functionality and multi-modal imaging across MRI, PET, SPECT, and ultrasound. These features could ultimately translate to clinical advantages such as earlier detection, real time assessment of disease progression and personalized medicine. However, several years of investigation into the application of these materials to cancer research has revealed challenges that have delayed the successful application of these agents to the field of biomedical imaging. Understanding these challenges is critical to take full advantage of the benefits offered by nano-sized imaging agents. Therefore, this article presents the lessons learned and challenges encountered by a group of leading researchers in this field, and suggests ways forward to develop nanoparticle probes for cancer imaging. Published by Elsevier Ltd. PMID:25419228

DNA nanosensor based on biocompatible graphene quantum dots and carbon nanotubes.

PubMed

Qian, Zhao Sheng; Shan, Xiao Yue; Chai, Lu Jing; Ma, Juan Juan; Chen, Jian Rong; Feng, Hui

2014-10-15

An ultrasensitive nanosensor based on fluorescence resonance energy transfer (FRET) between biocompatible graphene quantum dots and carbon nanotubes for DNA detection was reported. We take advantage of good biocompatibility and strong fluorescence of graphene quantum dots, base pairing specificity of DNA and unique fluorescence resonance energy transfer between graphene quantum dots and carbon nanotubes to achieve the analysis of low concentrations of DNA. Graphene quantum dots with high quantum yield up to 0.20 were prepared and served as the fluorophore of DNA probe. FRET process between graphene quantum dots-labeled probe and oxidized carbon nanotubes is easily achieved due to their efficient self-assembly through specific π-π interaction. This nanosensor can distinguish complementary and mismatched nucleic acid sequences with high sensitivity and good reproducibility. The detection method based on this nanosensor possesses a broad linear span of up to 133.0 nM and ultralow detection limit of 0.4 nM. The constructed nanosensor is expected to be highly biocompatible because of all its components with excellent biocompatibility. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantifying Interfacial pH Variation at Molecular Length Scales Using a Concurrent Non-Faradaic Reaction.

PubMed

Ryu, Jaeyune; Wuttig, Anna; Surendranath, Yogesh

2018-05-15

We quantify changes in the interfacial pH local to the electrochemical double layer during electrocatalysis, using a concurrent non-faradaic probe reaction. In the absence of electrocatalysis, nanostructured Pt/C surfaces mediate the reaction of H2 with cis-2-butene-1,4-diol to form a mixture of 1,4-butanediol and n-butanol with a selectivity that is linearly dependent on the bulk solution pH. We show that kinetic branching occurs from a common surface-bound intermediate, ensuring that this probe reaction is uniquely sensitive to the interfacial pH within molecular length scales of the surface. We use the pH-dependent selectivity of this reaction to track changes in interfacial pH during concurrent hydrogen oxidation electrocatalysis and find that the local pH can vary dramatically, > 3 units, relative to the bulk value even at modest current densities in well-buffered electrolytes. This work highlights the key role that interfacial pH variation plays in modulating inner-sphere electrocatalysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Opioid Receptor Probes Derived from Cycloaddition of the Hallucinogen Natural Product Salvinorin A†

PubMed Central

Lozama, Anthony; Cunningham, Christopher W.; Caspers, Michael J.; Douglas, Justin T.; Dersch, Christina M.; Rothman, Richard B.; Prisinzano, Thomas E.

2011-01-01

As part of our continuing efforts toward more fully understanding the structure-activity relationships of the neoclerodane diterpene salvinorin A, we report the synthesis and biological characterization of unique cycloadducts through [4+2] Diels-Alder cycloaddition. Microwave-assisted methods were developed and successfully employed, aiding in functionalizing the chemically sensitive salvinorin A scaffold. This demonstrates the first reported results for both cycloaddition of the furan ring and functionalization via microwave-assisted methodology of the salvinorin A skeleton. The cycloadducts yielded herein introduce electron-withdrawing substituents and bulky aromatic groups into the C-12 position. Kappa opioid (KOP) receptor space was explored through aromatization of the bent oxanorbornadiene system possessed by the cycloadducts to a planar phenyl ring system. Although dimethyl- and diethylcarboxylate analogues 5 and 6 retain some affinity and selectivity for KOP receptors and are full agonists, their aromatized counterparts 13 and 14 have reduced affinity for KOP receptors. The methods developed herein signify a novel approach toward rapidly probing the structure-activity relationships of furan containing natural products. PMID:21338114

Vertical-cavity surface-emitting laser sources for gigahertz-bandwidth, multiwavelength frequency-domain photon migration

NASA Astrophysics Data System (ADS)

O'Sullivan, Thomas D.; No, Keunsik; Matlock, Alex; Warren, Robert V.; Hill, Brian; Cerussi, Albert E.; Tromberg, Bruce J.

2017-10-01

Frequency-domain photon migration (FDPM) uses modulated laser light to measure the bulk optical properties of turbid media and is increasingly applied for noninvasive functional medical imaging in the near-infrared. Although semiconductor edge-emitting laser diodes have been traditionally used as miniature light sources for this application, we show that vertical-cavity surface-emitting lasers (VCSELs) exhibit output power and modulation performance characteristics suitable for FDPM measurements of tissue optical properties at modulation frequencies exceeding 1 GHz. We also show that an array of multiple VCSEL devices can be coherently modulated at frequencies suitable for FDPM and can improve optical power. In addition, their small size and simple packaging make them an attractive choice as components in wearable sensors and clinical FDPM-based optical spectroscopy systems. We demonstrate the benefits of VCSEL technology by fabricating and testing a unique, compact VCSEL-based optical probe with an integrated avalanche photodiode. We demonstrate sensitivity of the VCSEL-based probe to subcutaneous tissue hemodynamics that was induced during an arterial cuff occlusion of the upper arm in a human subject.

Atom Probe Tomography Analysis of Gallium-Nitride-Based Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Prosa, Ty J.; Olson, David; Giddings, A. Devin; Clifton, Peter H.; Larson, David J.; Lefebvre, Williams

2014-03-01

Thin-film light-emitting diodes (LEDs) composed of GaN/InxGa1-xN/GaN quantum well (QW) structures are integrated into modern optoelectronic devices because of the tunable InGaN band-gap enabling emission of the full visible spectrum. Atom probe tomography (APT) offers unique capabilities for 3D device characterization including compositional mapping of nano-volumes (>106 nm3) , high detection efficiency (>50%), and good sensitivity. In this study, APT is used to understand the distribution of dopants as well as Al and In alloying agents in a GaN device. Measurements using transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) have also been made to improve the accuracy of the APT analysis by correlating the information content of these complimentary techniques. APT analysis reveals various QW and other optoelectronic structures including a Mg p-GaN layer, an Al-rich electron blocking layer, an In-rich multi-QW region, and an In-based super-lattice structure. The multi-QW composition shows good quantitative agreement with layer thickness and spacing extracted from a high resolution TEM image intensity analysis.

Room temperature synthesis of pH-switchable polyaniline quantum dots as a turn-on fluorescent probe for acidic biotarget labeling.

PubMed

Liu, Yanfeng; Ding, Yin; Gou, Huilin; Huang, Xin; Zhang, Guiyang; Zhang, Qi; Liu, Yunzhong; Meng, Zhen; Xi, Kai; Jia, Xudong

2018-04-05

The synthesis of well-defined light-element-derived quantum dots (LEQDs) with advanced optical properties under mild conditions is highly desirable yet challenging. Here, a polyaniline (PANI) structure is introduced into carbon-rich LEQDs to yield well-defined, fluorescent polyaniline quantum dots (PAQDs), PAQD24, through a one-pot room temperature reaction. The mild synthetic conditions effectively minimize the defects introduced during the conventional synthesis and endow PAQD24 with desirable optical properties, including a narrow emission band (full width at half maximum = 55 nm), an optimal quantum yield of 32.5% and two-photon fluorescence. Furthermore, the bandgap of PAQD24 is highly sensitive toward pH variations in the near-neutral region, due to the proton doping and dedoping of the PANI structure. Such unique properties together with its fine bio-compatibility enable the application of this material as a turn-on fluorescent probe for the labeling of acidic biotargets from sub-cellular to organ levels, providing potential applications in diagnosis and surgery guidance for certain diseases.

Positron annihilation lifetime spectroscopy (PALS): a probe for molecular organisation in self-assembled biomimetic systems.

PubMed

Fong, Celesta; Dong, Aurelia W; Hill, Anita J; Boyd, Ben J; Drummond, Calum J

2015-07-21

Positron annihilation lifetime spectroscopy (PALS) has been shown to be highly sensitive to conformational, structural and microenvironmental transformations arising from subtle geometric changes in molecular geometry in self-assembling biomimetic systems. The ortho-positronium (oPs) may be considered an active probe that can provide information on intrinsic packing and mobility within low molecular weight solids, viscous liquids, and soft matter systems. In this perspective we provide a critical overview of the literature in this field, including the evolution of analysis software and experimental protocols with commentary upon the practical utility of PALS. In particular, we discuss how PALS can provide unique insight into the macroscopic transport properties of several porous biomembrane-like nanostructures and suggest how this insight may provide information on the release of drugs from these matrices to aid in developing therapeutic interventions. We discuss the potentially exciting and fruitful application of this technique to membrane dynamics, diffusion and permeability. We propose that PALS can provide novel molecular level information that is complementary to conventional characterisation techniques.

Characteristic effects of substituent and external pressure on group-inclusion complexation with p-sulfonatocalix[8]arene and γ-cyclodextrin

NASA Astrophysics Data System (ADS)

Miyazono, Keitaro; Hanaya, Tadashi; Sueishi, Yoshimi

2014-07-01

By synthesizing unique nitroxide probes (α-substituted phenyl-2,4,6-trimethoxybenzyl(t-butyl)nitroxide), we have shown that p-sulfonatocalix[8]arene (Calix-S8) and γ-cyclodextin (γ-CD) form electron spin resonance spectroscopically separable group-inclusion complexes (α-substituted phenyl-in (R-in) and t-butyl-in complexes) and determined the group-inclusion constants of Calix-S8 and γ-CD. Using nitroxide probes, we have examined the effects of substituent and external pressure on group-inclusion complexation with Calix-S8 and γ-CD. Experiments on pressure dependence enabled us to calculate the reaction volume (Δ V) for R-in and t-butyl-in complex formations. Δ V for group-in complexation with Calix-S8 had negative values. In contrast, Δ V values for γ-CD showed positive values, which is responsible for the repelled water molecules in the CD cavity. The characteristic pressure effects on group-in complexation suggest that group recognition by γ-CD is sensitive when compared with that by Calix-S8.

Impact of morphology on diffusive dynamics on curved surfaces

NASA Astrophysics Data System (ADS)

Kusters, Remy; Storm, Cornelis

2014-03-01

Diffusive processes on nonplanar substrates are deeply relevant for cellular function and transport and increasingly used to probe and characterize the behavior of proteins in membranes. We present analytical and numerical analyses of in-plane diffusion of discrete particles on curved geometries reflecting various generic motifs in biology and explore, in particular, the effect that the shape of the substrate has on the characteristic time scales of diffusive processes. To this end, we consider both collective measures (the relaxation of concentration profiles towards equilibrium) and single-particle measures (escape rates and first passage times of individual diffusing molecules): the first relevant for the correct interpretation of FRAP experiments in curved environments; the second, for single-particle tracking probes. Each of these measures is sensitively affected by the morphology of the substrate, and we find that the exit rate out of a domain is not uniquely set by the size of its boundary, illustrating the general principle we reveal: By varying the shape of a substrate, Nature can control the diffusive time scales in a microenvironment without changing the bare substrate properties.

In vivo Detection of Phospholipase C by Enzyme-Activated Near-infrared Probes

PubMed Central

Mawn, Theresa M.; Popov, Anatoliy V.; Beardsley, Nancy J.; Stefflova, Klara; Milkevitch, Matthew; Zheng, Gang; Delikatny, E. James

2011-01-01

In this paper the characterization of the first near-infrared (NIR) phospholipase-activated molecular beacon is reported and its utility for in vivo cancer imaging is demonstrated. The probe consists of three elements: a phospholipid (PL) backbone to which the NIR fluorophore, pyropheophorbide a (Pyro), and the NIR Black Hole Quencher 3 (BHQ) were conjugated. Due to the close proximity of BHQ to Pyro, the Pyro-PtdEtn-BHQ probe is self-quenched until enzyme hydrolysis releases the fluorophore. The Pyro-PtdEtn-BHQ probe is highly specific to one isoform of phospholipase C, phosphatidylcholine-specific phospholipase C (PC-PLC), responsible for catabolizing phosphatidylcholine directly to phosphocholine. Incubation of Pyro-PtdEtn-BHQ in vitro with PC-PLC demonstrated a 150-fold increase in fluorescence that could be inhibited by the specific PC-PLC inhibitor tricyclodecan-9-yl xanthogenate (D609) with an IC50 of 34±8 µM. Since elevations in phosphocholine have been consistently observed by magnetic resonance spectroscopy in a wide array of cancer cells and solid tumors, we assessed the utility of Pyro-PtdEtn-BHQ as a probe for targeted tumor imaging. Injection of Pyro-PtdEtn-BHQ into mice bearing DU145 human prostate tumor xenografts followed by in vivo NIR imaging resulted in a 4-fold increase in tumor radiance over background and a 2 fold increase in the tumor:muscle ratio. Tumor fluorescence enhancement was inhibited with administration of D609. The ability to image PC-PLC activity in vivo provides a unique and sensitive method of monitoring one of the critical phospholipase signaling pathways activated in cancer, as well as the phospholipase activities that are altered in response to cancer treatment. PMID:22034913

Non-invasive estimation of middle-ear input impedance and efficiency.

PubMed

Lewis, James D; Neely, Stephen T

2015-08-01

A method to transform the impedance measured in the ear canal, ZEC, to the plane of the eardrum, ZED, is described. The portion of the canal between the probe and eardrum was modeled as a concatenated series of conical segments, allowing for spatial variations in its cross-sectional area. A model of the middle ear (ME) and cochlea terminated the ear-canal model, which permitted estimation of ME efficiency. Acoustic measurements of ZEC were made at two probe locations in 15 normal-hearing subjects. ZEC was sensitive to measurement location, especially near frequencies of canal resonances and anti-resonances. Transforming ZEC to ZED reduced the influence of the canal, decreasing insertion-depth sensitivity of ZED between 1 and 12 kHz compared to ZEC. Absorbance, A, was less sensitive to probe placement than ZEC, but more sensitive than ZED above 5 kHz. ZED and A were similarly insensitive to probe placement between 1 and 5 kHz. The probe-placement sensitivity of ZED below 1 kHz was not reduced from that of either A or ZEC. ME efficiency had a bandpass shape with greatest efficiency between 1 and 4 kHz. Estimates of ZED and ME efficiency could extend the diagnostic capability of wideband-acoustic immittance measurements.

A colorimetric and fluorescent probe for detecting intracellular biothiols.

PubMed

Chen, Chunyang; Liu, Wei; Xu, Cong; Liu, Weisheng

2016-11-15

A new rapid and highly sensitive coumarin-based probe (probe 1) has been designed and synthesized for detecting intracellular thiols. Probe 1 was prepared by a 4-step procedure as a latent fluorescence probe to achieve high sensitivity and fluorescence turn-on response toward cysteine and homocysteine over GSH and other various natural amino acids under physiological conditions. Owing to specific cyclization between thiols and aldehyde group, probe 1 displayed a highly selectivity toward cysteine and homocysteine. Above all, probe 1 was successfully used for fluorescence imaging of biothiols in Hela cells, and quantitative determination had been achieved within a certain range. Then specific fluorescence imaging of mice organ tissues was obtained for proving the permeability of probe 1. Simultaneously, the viability was measured to be more than 80%, which shows probe 1 can be a rapid and biocompatible probe for biothiols in cells. Furthermore, the measurement of thiols detection in 5 kinds of animal serum showed that probe 1 can be used in determination of biothiols in blood. Copyright © 2016 Elsevier B.V. All rights reserved.

Magnetic induction spectroscopy (MIS)-probe design for cervical tissue measurements.

PubMed

Wang, Jau-Yi; Healey, Timothy; Barker, Anthony; Brown, Brian; Monk, Chris; Anumba, Dilly

2017-05-01

Gradiometers have the advantage of increasing measuring sensitivity, which is particularly useful in magnetic induction spectroscopy (MIS) for bio-impedance measurements. Traditional gradiometers use a pair of field sensing coils equally distant and on opposite sides of a drive coil, which provides high immunity to interference. In this paper, a ferrite-cored coaxial gradiometer probe of 29 mm diameter has been developed for measuring the impedance spectra of cervical tissues in vivo. It consists of a ferrite rod with outer ferrite confinement screening in order to eliminate the signals from surrounding tissue. The magnetic screening efficiency was compared with an air-cored gradiometer probe. For both gradiometer probes, a drive coil and two sensing coils were wound on a borosilicate glass former aligned coaxially with two sensing coils equidistant from the drive coil. The signal sensitivity of those two MIS gradiometers has been measured using saline samples with a conductivity range between 0.1 and 1.1 S m -1 . Finite element methods using COMSOL Multiphysics have been used to simulate the distribution of sensitivity to conductivity over the face of each probe and with depth. The ferrite-cored probe has a sensitivity confined to the volume defined by the gap between the ferrite core and outer tube of ferrite while the air-cored probe without any magnetic shielding had a wide sensitivity over the face and the side of the probe. Four saline samples and one of distilled water with conductivities from 0.1 to 1.1 S m -1 have been used to make conductivity measurements at frequencies of 50 kHz, 100 kHz, and 300 kHz. The measurement accuracy of the air-cored MIS probe was 0.09 S m -1 at 50 kHz, improving to 0.05 S m -1 at 300 kHz. For the ferrite-cored MIS probe, the measurement accuracy was 0.28 S m -1 at 50 kHz, improving to 0.04 S m -1 at 300 kHz. In vivo measurements on human hand have been performed using both types of gradiometers and the conductivity is consistent with reported data.

Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

PubMed

Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum

2014-06-10

In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

Design and Investigation of Optical Properties of N-(Rhodamine-B)-Lactam-Ethylenediamine (RhB-EDA) Fluorescent Probe.

PubMed

Soršak, Eva; Volmajer Valh, Julija; Korent Urek, Špela; Lobnik, Aleksandra

2018-04-14

This study presents chemical modification of a Rhodamine B (RhB) sensor probe by ethylenediamine (EDA), and investigation of its spectral as well as sensor properties to the various metals. The synthesised N -(Rhodamine-B)-lactam-ethylenediamine (RhB-EDA) fluorescent probe shows interesting optical sensor properties, and high sensitivity and selectivity to Ag⁺ ions among all the tested metal ions (K⁺, Mg 2+ , Cu 2+ , Ni 2+ , Fe 2+ , Pb 2+ , Na⁺, Mn 2+ , Li⁺, Al 3+ , Co 2+ , Hg 2+ , Sr 2+ , Ca 2+ , Ag⁺, Cd 2+ and Zn 2+ ), while the well-known Rhodamine B (RhB) fluorescent probe shows much less sensitivity to Ag⁺ ions, but high sensitivity to Fe 2+ ions. The novel fluorescent sensor probe RhB-EDA has the capabilities to sense Ag⁺ ions up to µM ranges by using the fluorescence quenching approach. The probe displayed a dynamic response to Ag⁺ in the range of 0.43 × 10 -3 -10 -6 M with a detection limit of 0.1 μM. The sensing system of an RhB-EDA novel fluorescent probe was optimised according to the spectral properties, effect of pH and buffer, photostability, incubation time, sensitivity, and selectivity. Since all the spectral and sensing properties were tested in green aqueous media, although many other similar sensor systems rely on organic solvent solutions, the RhB-EDA sensing probe may be a good candidate for measuring Ag⁺ ions in real-life applications.

Fluorescent kapakahines serve as non-toxic probes for live cell Golgi imaging.

PubMed

Rocha, Danilo D; Espejo, Vinson R; Rainier, Jon D; La Clair, James J; Costa-Lotufo, Letícia V

2015-09-01

There is an ongoing need for fluorescent probes that specifically-target select organelles within mammalian cells. This study describes the development of probes for the selective labeling of the Golgi apparatus and offers applications for live cell and fixed cell imaging. The kapakahines, characterized by a common C(3)-N(1') dimeric tryptophan linkage, comprise a unique family of bioactive marine depsipeptide natural products. We describe the uptake and subcellular localization of fluorescently-labeled analogs of kapakahine E. Using confocal microscopy, we identify a rapid and selective localization within the Golgi apparatus. Comparison with commercial Golgi stains indicates a unique localization pattern, which differs from currently available materials, therein offering a new tool to monitor the Golgi in live cells without toxic side effects. This study identifies a fluorescent analog of kapakahine E that is rapidly uptaken in cells and localizes within the Golgi apparatus. The advance of microscopic methods is reliant on the parallel discovery of next generation molecular probes. This study describes the advance of stable and viable probe for staining the Golgi apparatus. Copyright © 2015 Elsevier Inc. All rights reserved.

Highly water-soluble BODIPY-based fluorescent probe for sensitive and selective detection of nitric oxide in living cells.

PubMed

Vegesna, Giri K; Sripathi, Srinivas R; Zhang, Jingtuo; Zhu, Shilei; He, Weilue; Luo, Fen-Tair; Jahng, Wan Jin; Frost, Megan; Liu, Haiying

2013-05-22

A highly water-soluble BODIPY dye bearing electron-rich o-diaminophenyl groups at 2,6-positions was prepared as a highly sensitive and selective fluorescent probe for detection of nitric oxide (NO) in living cells. The fluorescent probe displays an extremely weak fluorescence with fluorescence quantum yield of 0.001 in 10 mM phosphate buffer (pH 7.0) in the absence of NO as two electron-rich o-diaminophenyl groups at 2,6-positions significantly quench the fluorescence of the BODIPY dye via photoinduced electron transfer mechanism. The presence of NO in cells enhances the dye fluorescence dramatically. The fluorescent probe demonstrates excellent water solubility, membrane permeability, and compatibility with living cells for sensitive detection of NO.

Evidence for Dynamic Chemical Kinetics at Individual Molecular Ruthenium Catalysts.

PubMed

Easter, Quinn T; Blum, Suzanne A

2018-02-05

Catalytic cycles are typically depicted as possessing time-invariant steps with fixed rates. Yet the true behavior of individual catalysts with respect to time is unknown, hidden by the ensemble averaging inherent to bulk measurements. Evidence is presented for variable chemical kinetics at individual catalysts, with a focus on ring-opening metathesis polymerization catalyzed by the second-generation Grubbs' ruthenium catalyst. Fluorescence microscopy is used to probe the chemical kinetics of the reaction because the technique possesses sufficient sensitivity for the detection of single chemical reactions. Insertion reactions in submicron regions likely occur at groups of many (not single) catalysts, yet not so many that their unique kinetic behavior is ensemble averaged. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Thermally Stable and Highly Fluorescent IR Dyes

NASA Technical Reports Server (NTRS)

Bu, Xiu R.

2004-01-01

Fluorophores are the core component in various optical applications such as sensors and probes. Fluorphores with low-energy or long wavelength emission, in particular, in NIR region, possess advantages of low interference and high sensitivity. In this study, we has explored several classes of imidazole-based compounds for NIR fluorescent properties and concluded: (1) thiazole-based imidazole compounds are fluorescent; (2) emission energy is tunable by additional donor groups; (3) they also possess impressive two- photon absorption properties; and (4) fluorescence emission can be induced by two- photon input. This report summarizes (1) synthesis of new series of fluorophore; (2) impact of electron-withdrawing groups on fluorescent property; (3) unique property of two-photon absorption; and (4) on-going development.

Quantitative Velocity Field Measurements in Reduced-Gravity Combustion Science and Fluid Physics Experiments

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.; Wernet, Mark P.

1999-01-01

Systems have been developed and demonstrated for performing quantitative velocity measurements in reduced gravity combustion science and fluid physics investigations. The unique constraints and operational environments inherent to reduced-gravity experimental facilities pose special challenges to the development of hardware and software systems. Both point and planar velocimetric capabilities are described, with particular attention being given to the development of systems to support the International Space Station laboratory. Emphasis has been placed on optical methods, primarily arising from the sensitivity of the phenomena of interest to intrusive probes. Limitations on available power, volume, data storage, and attendant expertise have motivated the use of solid-state sources and detectors, as well as efficient analysis capabilities emphasizing interactive data display and parameter control.

Simultaneous fast scanning XRF, dark field, phase-, and absorption contrast tomography

NASA Astrophysics Data System (ADS)

Medjoubi, Kadda; Bonissent, Alain; Leclercq, Nicolas; Langlois, Florent; Mercère, Pascal; Somogyi, Andrea

2013-09-01

Scanning hard X-ray nanoprobe imaging provides a unique tool for probing specimens with high sensitivity and large penetration depth. Moreover, the combination of complementary techniques such as X-ray fluorescence, absorption, phase contrast and dark field imaging gives complete quantitative information on the sample structure, composition and chemistry. The multi-technique "FLYSCAN" data acquisition scheme developed at Synchrotron SOLEIL permits to perform fast continuous scanning imaging and as such makes scanning tomography techniques feasible in a time-frame well-adapted to typical user experiments. Here we present the recent results of simultaneous fast scanning multi-technique tomography performed at Soleil. This fast scanning scheme will be implemented at the Nanoscopium beamline for large field of view 2D and 3D multimodal imaging.

Dissipative Dynamics with Exotic Beams

NASA Astrophysics Data System (ADS)

di Toro, M.; Colonna, M.; Greco, V.; Ferini, G.; Rizzo, C.; Rizzo, J.; Baran, V.; Wolter, H. H.; Zielinska-Pfabe, M.

2008-04-01

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation and at high nucleon momenta. In this report we present a selection of reaction observables particularly sensitive to the isovector part of the interaction, i.e. to the symmetry term of the nuclear Equation of State (EoS) At low and Fermi energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. Predictions are shown for fusion, deep-inelastic and fragmentation collisions induced by neutron rich projectiles. At all energies the isospin transport data are supplying valuable information on value and slope of the symmetry term below saturation. The importance of studying violent collisions with radioactive beams in this energy range is finally stressed.

Exposing the dark sector with future Z factories

NASA Astrophysics Data System (ADS)

Liu, Jia; Wang, Lian-Tao; Wang, Xiao-Ping; Xue, Wei

2018-05-01

We investigate the prospects of searching dark sector models via exotic Z -boson decay at future e+e- colliders with Giga Z and Tera Z options. Four general categories of dark sector models, Higgs portal dark matter, vector-portal dark matter, inelastic dark matter, and axionlike particles, are considered. Focusing on channels motivated by the dark sector models, we carry out a model-independent study of the sensitivities of Z factories in probing exotic decays. The limits on branching ratios of the exotic Z decay are typically O (10-6- 10-8.5) for the Giga Z and O (10-7.5- 10-11) for the Tera Z , and they are compared with the projection for the high luminosity LHC. We demonstrate that future Z factories can provide its unique and leading sensitivity and highlight the complementarity with other experiments, including the indirect and direct dark matter search limits and the existing collider limits. Future Z factories will play a leading role in uncovering the hidden sector of the Universe in the future.

Colorimetric and luminescent bifunctional iridium(III) complexes for the sensitive recognition of cyanide ions

NASA Astrophysics Data System (ADS)

Chen, Xiudan; Wang, Huili; Li, Jing; Hu, Wenqin; Li, Mei-Jin

2017-02-01

Two new cyclometalated iridium(III) complexes [(ppy)2Irppz]Cl (1) and [(ppy)2Irbppz]Cl (2) (where ppy = 2-phenylpyridine, ppz = 4,7-phenanthrolino-5,6:5,6-pyrazine, bppz = 2.3-di-2-pyridylpyrazine), were designed and synthesized. The structure of [(ppy)2Irppz]Cl was determined by single crystal X-ray diffraction. Their photophysical properties were also studied. This kind of complexes could coordinate with Cu2 +, the photoluminescence (PL) of the complex was quenched, and the color changed from orange-red to green. The forming M-Cu (M: complexes 1 and 2) ensemble could be further utilized as a colorimetric and emission ;turn-on; bifunctional detection for CN-, especially for complex 1-Cu2 + showed a high sensitivity toward CN- with a limit of diction is 97 nM. Importantly, this kind of iridium(III) complexes shows a unique recognition of cyanide ions over other anions which makes it an eligible sensing probe for cyanide ions.

Using Multifunctional Peptide Conjugated Au Nanorods for Monitoring β-amyloid Aggregation and Chemo-Photothermal Treatment of Alzheimer's Disease.

PubMed

Li, Meng; Guan, Yijia; Zhao, Andong; Ren, Jinsong; Qu, Xiaogang

2017-01-01

Development of sensitive detectors of Aβ aggregates and effective inhibitors of Aβ aggregation are of diagnostic importance and therapeutic implications for Alzheimer's disease (AD) treatment. Herein, a novel strategy has been presented by self-assembly of peptide conjugated Au nanorods (AuP) as multifunctional Aβ fibrillization detectors and inhibitors. Our design combines the unique high NIR absorption property of AuNRs with two known Aβ inhibitors, Aβ15-20 and polyoxometalates (POMs). The synthesized AuP can effectively inhibit Aβ aggregation and dissociate amyloid deposits with NIR irradiation both in buffer and in mice cerebrospinal fluid (CSF), and protect cells from Aβ-related toxicity upon NIR irradiation. In addition, with the shape and size-dependent optical properties, the nanorods can also act as effective diagnostic probes to sensitively detect the Aβ aggregates. This is the first report to integrate 3 segments, an Aβ-targeting element, a reporter and inhibitors, in one drug delivery system for AD treatment.

Using Multifunctional Peptide Conjugated Au Nanorods for Monitoring β-amyloid Aggregation and Chemo-Photothermal Treatment of Alzheimer's Disease

PubMed Central

Li, Meng; Guan, Yijia; Zhao, Andong; Ren, Jinsong; Qu, Xiaogang

2017-01-01

Development of sensitive detectors of Aβ aggregates and effective inhibitors of Aβ aggregation are of diagnostic importance and therapeutic implications for Alzheimer's disease (AD) treatment. Herein, a novel strategy has been presented by self-assembly of peptide conjugated Au nanorods (AuP) as multifunctional Aβ fibrillization detectors and inhibitors. Our design combines the unique high NIR absorption property of AuNRs with two known Aβ inhibitors, Aβ15-20 and polyoxometalates (POMs). The synthesized AuP can effectively inhibit Aβ aggregation and dissociate amyloid deposits with NIR irradiation both in buffer and in mice cerebrospinal fluid (CSF), and protect cells from Aβ-related toxicity upon NIR irradiation. In addition, with the shape and size-dependent optical properties, the nanorods can also act as effective diagnostic probes to sensitively detect the Aβ aggregates. This is the first report to integrate 3 segments, an Aβ-targeting element, a reporter and inhibitors, in one drug delivery system for AD treatment. PMID:28839459

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.

Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase

PubMed Central

Chen, Kuan-Chieh; Li, Yu-Le; Wu, Chao-Wei

2018-01-01

In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future. PMID:29659536

Glucose Sensor Using U-Shaped Optical Fiber Probe with Gold Nanoparticles and Glucose Oxidase.

PubMed

Chen, Kuan-Chieh; Li, Yu-Le; Wu, Chao-Wei; Chiang, Chia-Chin

2018-04-16

In this study, we proposed a U-shaped optical fiber probe fabricated using a flame heating method. The probe was packaged in glass tube to reduce human factors during experimental testing of the probe as a glucose sensor. The U-shaped fiber probe was found to have high sensitivity in detecting the very small molecule. When the sensor was dipped in solutions with different refractive indexes, its wavelength or transmission loss changed. We used electrostatic self-assembly to bond gold nanoparticles and glucose oxidase (GOD) onto the sensor’s surface. The results over five cycles of the experiment showed that, as the glucose concentration increased, the refractive index of the sensor decreased and its spectrum wavelength shifted. The best wavelength sensitivity was 2.899 nm/%, and the linearity was 0.9771. The best transmission loss sensitivity was 5.101 dB/%, and the linearity was 0.9734. Therefore, the proposed U-shaped optical fiber probe with gold nanoparticles and GOD has good potential for use as a blood sugar sensor in the future.

Visualization of nucleic acids with synthetic exciton-controlled fluorescent oligonucleotide probes.

PubMed

Wang, Dan Ohtan; Okamoto, Akimitsu

2015-01-01

Engineered probes to adapt new photochemical properties upon recognition of target nucleic acids offer powerful tools to DNA and RNA visualization technologies. Herein, we describe a rapid and effective visualization method of nucleic acids in both fixed and living cells with hybridization-sensitive fluorescent oligonucleotide probes. These probes are efficiently quenched in an aqueous environment due to the homodimeric, excitonic interactions between fluorophores but become highly fluorescent upon hybridization to DNA or RNA with complementary sequences. The fast hybridization kinetics and quick fluorescence activation of the new probes allow applications to simplify the conventional fluorescent in situ hybridization protocols and reduce the amount of time to process the samples. Furthermore, hybridization-sensitive fluorescence emission of the probes allows monitoring dynamic behaviors of RNA in living cells.

Rugged fiber optic probe for raman measurement

DOEpatents

O'Rourke, Patrick E.; Toole, Jr., William R.; Nave, Stanley E.

1998-01-01

An optical probe for conducting light scattering analysis is disclosed. The probe comprises a hollow housing and a probe tip. A fiber assembly made up of a transmitting fiber and a receiving bundle is inserted in the tip. A filter assembly is inserted in the housing and connected to the fiber assembly. A signal line from the light source and to the spectrometer also is connected to the filter assembly and communicates with the fiber assembly. By using a spring-loaded assembly to hold the fiber connectors together with the in-line filters, complex and sensitive alignment procedures are avoided. The close proximity of the filter assembly to the probe tip eliminates or minimizes self-scattering generated by the optical fiber. Also, because the probe can contact the sample directly, sensitive optics can be eliminated.

Evaluation of ion-implanted-silicon detectors for use in intraoperative positron-sensitive probes.

PubMed

Raylman, R R; Wahl, R L

1996-11-01

The continuing development of probes for use with beta (positron and electron) emitting radionuclides may result in more complete excision of tracer-avid tumors. Perhaps one of the most promising radiopharmaceuticals for this task is 18F-labeled-Fluoro-2-Deoxy-D-Glucose (FDG). This positron-emitting agent has been demonstrated to be avidly and rapidly absorbed by many human cancers. We have investigated the use of ion-implanted-silicon detectors in intraoperative positron-sensitive surgical probes for use with FDG. These detectors possess very high positron detection efficiency, while the efficiency for 511 keV photon detection is low. The spatial resolution, as well as positron and annihilation photon detection sensitivity, of an ion-implanted-silicon detector used with 18F was measured at several energy thresholds. In addition, the ability of the device to detect the presence of relatively small amounts of FDG during surgery was evaluated by simulating a surgical field in which some tumor was left intact following lesion excision. The performance of the ion-implanted-silicon detector was compared to the operating characteristics of a positron-sensitive surgical probe which utilizes plastic scintillator. In all areas of performance the ion-implanted-silicon detector proved superior to the plastic scintillator-based probe. At an energy threshold of 14 keV positron sensitivity measured for the ion-implanted-silicon detector was 101.3 cps/kBq, photon sensitivity was 7.4 cps/kBq. In addition, spatial resolution was found to be relatively unaffected by the presence of distant sources of annihilation photon flux. Finally, the detector was demonstrated to be able to localize small amounts of FDG in a simulated tumor bed; indicating that this device has promise as a probe to aid in FDG-guided surgery.

Deciphering the Sensitivity and Specificity of the Implantable Doppler Probe in Free Flap Monitoring.

PubMed

Chang, Edward I; Ibrahim, Amir; Zhang, Hong; Liu, Jun; Nguyen, Alexander T; Reece, Gregory P; Yu, Peirong

2016-03-01

The efficacy of implantable Doppler probes remains an area of considerable debate. This study aims to decipher its sensitivity and specificity for free flap monitoring. A retrospective review of all free flaps with an implantable Doppler probe was performed between 2000 and 2012. A Cook-Swartz implantable Doppler probe was used in 439 patients (head and neck, n = 364; breast, n = 53; extremity, n = 22), and demonstrated equivalent sensitivity and specificity between flap types. The overall sensitivity and specificity were 77.8 percent and 88.4 percent, respectively. The artery was monitored in 267 patients, compared to venous monitoring in 101 patients, and in 71 patients both the artery and vein were monitored. Arterial monitoring had significantly greater specificity than venous monitoring, (94.2 percent versus 74.0 percent; p < 0.001), but no benefit was found in monitoring both the artery and the vein. Venous monitoring was significantly associated with reoperation (OR, 3.17; 95 percent CI, 1.70 to 5.91; p = 0.0003). There were 284 flaps that had a monitoring segment in addition to the implantable Doppler probe that significantly increased overall specificity for microvascular complications (OR, 17.71; 95 percent CI, 3.39 to 92.23; p = 0.0006). The specificity (90.5 percent versus 84.8 percent) and sensitivity (80.0 percent versus 66.7 percent) were significantly higher for clinically monitored flaps. The take-back rate was 13.0 percent, with positive findings in 59.6 percent, and 5.2 percent total flap loss. The use of implantable Doppler probes has high sensitivity and specificity for buried free flaps despite positive findings in less than 60 percent of take-backs. Monitoring the artery is recommended, but clinical examination remains the gold standard for flap monitoring. Diagnostic, IV.

Fluorescent probes sensitive to changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during atherosclerosis

NASA Astrophysics Data System (ADS)

Posokhov, Yevgen

2016-09-01

Environment-sensitive fluorescent probes were used for the spectroscopic visualization of pathological changes in human platelet membranes during cerebral atherosclerosis. It has been estimated that the ratiometric probes 2-(2‧-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole and 2-phenyl-phenanthr[9,10]oxazole can detect changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during the disease.

Highly sensitive MicroRNA 146a detection using a gold nanoparticle-based CTG repeat probing system and isothermal amplification.

PubMed

Le, Binh Huy; Seo, Young Jun

2018-01-25

We have developed a gold nanoparticle (AuNP)-based CTG repeat probing system displaying high quenching capability and combined it with isothermal amplification for the detection of miRNA 146a. This method of using a AuNP-based CTG repeat probing system with isothermal amplification allowed the highly sensitive (14 aM) and selective detection of miRNA 146a. A AuNP-based CTG repeat probing system having a hairpin structure and a dT F fluorophore exhibited highly efficient quenching because the CTG repeat-based stable hairpin structure imposed a close distance between the AuNP and the dT F residue. A small amount of miRNA 146a induced multiple copies of the CAG repeat sequence during rolling circle amplification; the AuNP-based CTG repeat probing system then bound to the complementary multiple-copy CAG repeat sequence, thereby inducing a structural change from a hairpin to a linear structure with amplified fluorescence. This AuNP-based CTG probing system combined with isothermal amplification could also discriminate target miRNA 146a from one- and two-base-mismatched miRNAs (ORN 1 and ORN 2, respectively). This simple AuNP-based CTG probing system, combined with isothermal amplification to induce a highly sensitive change in fluorescence, allows the detection of miRNA 146a with high sensitivity (14 aM) and selectivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Hierarchical Flowerlike Gold Nanoparticles Labeled Immunochromatography Test Strip for Highly Sensitive Detection of Escherichia coli O157:H7.

PubMed

Zhang, Lei; Huang, Youju; Wang, Jingyun; Rong, Yun; Lai, Weihua; Zhang, Jiawei; Chen, Tao

2015-05-19

Gold nanoparticles (AuNPs) labeled lateral-flow test strip immunoassay (LFTS) has been widely used in biomedical, feed/food, and environmental analysis fields. Conventional ILFS assay usually uses spherical AuNPs as labeled probes and shows low detection sensitivity, which further limits its widespread practical application. Unlike spherical AuNP used as labeled probe in conventional ILFS, in our present study, a hierarchical flowerlike AuNP specific probe was designed for LFTS and further used to detect Escherichia coli O157:H7 (E. coli O157:H7). Three types of hierarchical flowerlike AuNPs, such as tipped flowerlike, popcornlike, and large-sized flowerlike AuNPs were synthesized in a one-step method. Compared with other two kinds of Au particles, tipped flowerlike AuNPs probes for LFTS particularly exhibited highly sensitive detection of E. coli O157:H7. The remarkable improvement of detection sensitivity of tipped flowerlike AuNPs probes can be achieved even as low as 10(3) colony-forming units (CFU)/mL by taking advantages of its appropriate size and hierarchical structures, which is superior over the detection performance of conventional LFTS. Using this novel tipped flower AuNPs probes, quantitative detection of E. coli O157:H7 can be obtained partially in a wide concentration range with good repeatability. This hierarchical tipped flower-shaped AuNPs probe for LFTS is promising for the practical applications in widespread analysis fields.

High sensitive vectorial B-probe for low frequency plasma waves.

PubMed

Ullrich, Stefan; Grulke, Olaf; Klinger, Thomas; Rahbarnia, Kian

2013-11-01

A miniaturized multidimensional magnetic probe is developed for application in a low-temperature plasma environment. A very high sensitivity for low-frequency magnetic field fluctuations with constant phase run, a very good signal-to-noise ratio combined with an efficient electrostatic pickup rejection, renders the probe superior compared with any commercial solution. A two-step calibration allows for absolute measurement of amplitude and direction of magnetic field fluctuations. The excellent probe performance is demonstrated by measurements of the parallel current pattern of coherent electrostatic drift wave modes in the VINETA (versatile instrument for studies on nonlinearity, electromagnetism, turbulence, and applications) experiment.

Highly specific detection of genetic modification events using an enzyme-linked probe hybridization chip.

PubMed

Zhang, M Z; Zhang, X F; Chen, X M; Chen, X; Wu, S; Xu, L L

2015-08-10

The enzyme-linked probe hybridization chip utilizes a method based on ligase-hybridizing probe chip technology, with the principle of using thio-primers for protection against enzyme digestion, and using lambda DNA exonuclease to cut multiple PCR products obtained from the sample being tested into single-strand chains for hybridization. The 5'-end amino-labeled probe was fixed onto the aldehyde chip, and hybridized with the single-stranded PCR product, followed by addition of a fluorescent-modified probe that was then enzymatically linked with the adjacent, substrate-bound probe in order to achieve highly specific, parallel, and high-throughput detection. Specificity and sensitivity testing demonstrated that enzyme-linked probe hybridization technology could be applied to the specific detection of eight genetic modification events at the same time, with a sensitivity reaching 0.1% and the achievement of accurate, efficient, and stable results.

The development of simple and sensitive small-molecule fluorescent probes for the detection of serum proteins after native polyacrylamide gel electrophoresis.

PubMed

Wang, Fangfang; Huang, Lingyun; Na, Na; He, Dacheng; Sun, Dezhi; Ouyang, Jin

2012-05-21

In this paper, a simple and sensitive small-molecule fluorescent probe, 2,5-dihydroxy-4'-dimethylaminochalcone (DHDMAC), was designed and synthesized for the detection of human serum proteins via hydrophobic interactions after polyacrylamide gel electrophoresis (PAGE). This probe produced lower fluorescence emission in the absence of proteins, and the emission intensity was significantly increased after the interaction with serum proteins. To demonstrate the imaging performance of this probe as a fluorescent dye, a series of experiments was conducted that included sensitivity comparison and 2D-PAGE. The results indicated that the sensitivity of DHDMAC staining is comparable to that of the most widely used fluorescent dye, SYPRO Ruby, and more protein spots (including thyroxine-binding globulin, angiotensinogen, afamin, zinc-α-2-glycoprotein and α-1-antichymotrypsin) were detected after 2D-PAGE. Therefore, DHDMAC is a good protein reporter due to its fast staining procedure, low detection limits and high resolution.

Radial-probe EBUS for the diagnosis of peripheral pulmonary lesions

PubMed Central

Jacomelli, Marcia; Demarzo, Sergio Eduardo; Cardoso, Paulo Francisco Guerreiro; Palomino, Addy Lidvina Mejia; Figueiredo, Viviane Rossi

2016-01-01

ABSTRACT Objective: Conventional bronchoscopy has a low diagnostic yield for peripheral pulmonary lesions. Radial-probe EBUS employs a rotating ultrasound transducer at the end of a probe that is passed through the working channel of the bronchoscope. Radial-probe EBUS facilitates the localization of peripheral pulmonary nodules, thus increasing the diagnostic yield. The objective of this study was to present our initial experience using radial-probe EBUS in the diagnosis of peripheral pulmonary lesions at a tertiary hospital. Methods: We conducted a retrospective analysis of 54 patients who underwent radial-probe EBUS-guided bronchoscopy for the investigation of pulmonary nodules or masses between February of 2012 and September of 2013. Radial-probe EBUS was performed with a flexible 20-MHz probe, which was passed through the working channel of the bronchoscope and advanced through the bronchus to the target lesion. For localization of the lesion and for collection procedures (bronchial brushing, transbronchial needle aspiration, and transbronchial biopsy), we used fluoroscopy. Results: Radial-probe EBUS identified 39 nodules (mean diameter, 1.9 ∓ 0.7 cm) and 19 masses (mean diameter, 4.1 ∓ 0.9 cm). The overall sensitivity of the method was 66.7% (79.5% and 25.0%, respectively, for lesions that were visible and not visible by radial-probe EBUS). Among the lesions that were visible by radial-probe EBUS, the sensitivity was 91.7% for masses and 74.1% for nodules. The complications were pneumothorax (in 3.7%) and bronchial bleeding, which was controlled bronchoscopically (in 9.3%). Conclusions: Radial-probe EBUS shows a good safety profile, a low complication rate, and high sensitivity for the diagnosis of peripheral pulmonary lesions. PMID:27832231

Evaluation of in vivo solid phase microextraction for minimally invasive analysis of nonvolatile phytochemicals in Amazonian plants.

PubMed

Musteata, Florin Marcel; Sandoval, Manuel; Ruiz-Macedo, Juan C; Harrison, Kathleen; McKenna, Dennis; Millington, William

2016-08-24

Although solid phase microextraction (SPME) has been used extensively for fingerprinting volatile compounds emitted by plants, there are very few such reports for direct insertion SPME. In this research, direct contact of SPME probes with the interstitial fluid of plants was investigated as a method for phytochemical analysis. Medicinal plants from the Amazon have been the source of numerous drugs used in western medicine. However, a large number of species used in traditional medicine have not been characterized chemically, partly due to the difficulty of field work. In this project, the phytochemical composition of plants from several genera was fingerprinted by combining convenient field sampling by solid phase microextraction (SPME) with laboratory analysis by LC-MS. The new method was compared with classical sampling followed by liquid extraction (LE). SPME probes were prepared by coating stainless steel wires with a mixture of polyacrylonitrile and either RP-amide or HS-F5 silica particles. Sampling was performed by inserting the microextraction probes into various tissues of living plants in their natural environment. After in vivo extraction, the probes were sealed under vacuum and refrigerated until analyzed. The probes were desorbed in mobile phase and analyzed on a Waters Acquity UPLC with triple quadrupole mass spectrometer in positive ion mode. Twenty Amazonian plant species were sampled and unique metabolomic fingerprints were obtained. In addition, quantitative analysis was performed for previously identified compounds in three species. Comparison of the fingerprints obtained by in vivo SPME with those obtained by LE showed that 27% of the chromatographic features were unique to SPME, 57% were unique to LE, and 16% were common to both methods. In vivo SPME caused minimal damage to the plants, was much faster than traditional liquid extraction, and provided unique fingerprints for all investigated plants. SPME revealed unique chromatographic features, undetected by traditional extraction, although it produced only half as many peaks as ethanol extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

Recent Progress in Fluorescent Imaging Probes

PubMed Central

Pak, Yen Leng; Swamy, K. M. K.; Yoon, Juyoung

2015-01-01

Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn2+, Hg2+, Cu2+ and Au3+, and anions including cyanide and adenosine triphosphate (ATP). PMID:26402684

Recent Progress in Fluorescent Imaging Probes.

PubMed

Pak, Yen Leng; Swamy, K M K; Yoon, Juyoung

2015-09-22

Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn(2+), Hg(2+), Cu(2+) and Au(3+), and anions including cyanide and adenosine triphosphate (ATP).

Synthesis and evaluation of sensitizer drug photorelease chemistry: Micro-optic method applied to singlet oxygen generation and drug delivery

NASA Astrophysics Data System (ADS)

Ghosh, Goutam

This thesis summarizes a new micro-optic method for singlet oxygen generation and sensitizer drug delivery, which include i) synthesis and evaluation of a first generation device for drug delivery from native and fluorinated silica probe tips, ii) synthesis of PEG conjugated sensitizers to study phototoxicity in ovarian cancer cells, and iii) synthesis and evaluation of tris-PEGylated chlorin conjugated fluorinated silica for its future integration into the device to use as a 2nd generation device. A first generation micro-optic device was developed that works by sparging O2 gas and light generating cytotoxic singlet oxygen that cleaves the covalently attached drug (sensitizer) from the probe tip at the distal end of the fiber. The aim is to develop a 1st and 2nd generation device for site specific delivery of photosensitizer and singlet oxygen to overcome the challenges involved in systemic administration of the sensitizer. Synthesis and evaluation of drug (pheophorbide-a) delivery applying micro-optic method from native and fluorinated silica probe tip was achieved. The amount of sensitizer photocleavage depends on the loading level of sensitizer onto the probe tips. We also found that photorelease efficiency depends on the nature of the solvents where sensitizer is photocleaved. For example, no photorelease was observed in an aqueous solvent where sensitizer remained adsorbed to the native silica probe-tip. But, 90% photocleavage was obtained in octanol. A significant amount of photosensitizer (formate ester of pyropheophorbide- a) diffused into the liposome when photocleavage study was carried out in liposome. Substantial increase of photorelease was observed in organic solvent when pyropheophorbide-a (PPa) sensitizer was attached to the partially fluorinated porous Vycor glass. We also explored sensitizer photorelease from the fluorinated silica surface at various temperatures and we found that autocatalytic photorelease happened at room temperature and above. No photorelease was observed at low temperature. Chlorin e6 and its one, two and three short chain methoxy triethylene glycol (PEG) conjugated derivatives were synthesized. A comparative study of photocytotoxicity and cellular uptake between each showed that 17 3,152,131- chlorin e6 methoxy triethylene glycol triester has the highest photocytotoxic activity and uptake by ovarian OVCAR-5 cancer cells. Therefore, we decided to load three short chain PEG conjugated chlorin e6 onto the silica surface through spacer alkene for delivery via a fiber-optic probe tip. In order to load chlorin e6-triPEG ester conjugate, in chapter 4, we explored different synthetic strategies. We have been successful in synthesizing spacer alkene succinate linker conjugated chlorin e6 -tri PEG ester, which was attached to the fiber-optic probe tip. Reactions were carried out in mild conditions to avoid detachment of the PEG ester from the carboxylic acid sites of chlorin. Photocleavage of the triPEG modified fluorinated probe tip system was studied in n-butanol.

Advances in using MRI probes and sensors for in vivo cell tracking as applied to regenerative medicine

PubMed Central

Srivastava, Amit K.; Kadayakkara, Deepak K.; Bar-Shir, Amnon; Gilad, Assaf A.; McMahon, Michael T.; Bulte, Jeff W. M.

2015-01-01

The field of molecular and cellular imaging allows molecules and cells to be visualized in vivo non-invasively. It has uses not only as a research tool but in clinical settings as well, for example in monitoring cell-based regenerative therapies, in which cells are transplanted to replace degenerating or damaged tissues, or to restore a physiological function. The success of such cell-based therapies depends on several critical issues, including the route and accuracy of cell transplantation, the fate of cells after transplantation, and the interaction of engrafted cells with the host microenvironment. To assess these issues, it is necessary to monitor transplanted cells non-invasively in real-time. Magnetic resonance imaging (MRI) is a tool uniquely suited to this task, given its ability to image deep inside tissue with high temporal resolution and sensitivity. Extraordinary efforts have recently been made to improve cellular MRI as applied to regenerative medicine, by developing more advanced contrast agents for use as probes and sensors. These advances enable the non-invasive monitoring of cell fate and, more recently, that of the different cellular functions of living cells, such as their enzymatic activity and gene expression, as well as their time point of cell death. We present here a review of recent advancements in the development of these probes and sensors, and of their functioning, applications and limitations. PMID:26035841

DNA Meter: Energy Tunable, Quantitative Hybridization Assay

PubMed Central

Braunlin, William; Völker, Jens; Plum, G. Eric; Breslauer, Kenneth J.

2015-01-01

We describe a novel hybridization assay that employs a unique class of energy tunable, bulge loop-containing competitor strands (C*) that hybridize to a probe strand (P). Such initial “pre-binding” of a probe strand modulates its effective “availability” for hybridizing to a target site (T). More generally, the assay described here is based on competitive binding equilibria for a common probe strand (P) between such tunable competitor strands (C*) and a target strand (T). We demonstrate that loop variable, energy tunable families of C*P complexes exhibit enhanced discrimination between targets and mismatched targets, thereby reducing false positives/negatives. We refer to a C*P complex between a C* competitor single strand and the probe strand as a “tuning fork,” since the C* strand exhibits branch points (forks) at the duplex-bulge interfaces within the complex. By varying the loop to create families of such “tuning forks,” one can construct C*P “energy ladders” capable of resolving small differences within the target that may be of biological/functional consequence. The methodology further allows quantification of target strand concentrations, a determination heretofore not readily available by conventional hybridization assays. The dual ability of this tunable assay to discriminate and quantitate targets provides the basis for developing a technology we refer to as a “DNA Meter.” Here we present data that establish proof-of-principle for an in solution version of such a DNA Meter. We envision future applications of this tunable assay that incorporate surface bound/spatially resolved DNA arrays to yield enhanced discrimination and sensitivity. PMID:23529692

Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates.

PubMed

Kovalev, S; Green, B; Golz, T; Maehrlein, S; Stojanovic, N; Fisher, A S; Kampfrath, T; Gensch, M

2017-03-01

Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systems and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.

Dynamical sensitivity control of a single-spin quantum sensor.

PubMed

Lazariev, Andrii; Arroyo-Camejo, Silvia; Rahane, Ganesh; Kavatamane, Vinaya Kumar; Balasubramanian, Gopalakrishnan

2017-07-26

The Nitrogen-Vacancy (NV) defect in diamond is a unique quantum system that offers precision sensing of nanoscale physical quantities at room temperature beyond the current state-of-the-art. The benchmark parameters for nanoscale magnetometry applications are sensitivity, spectral resolution, and dynamic range. Under realistic conditions the NV sensors controlled by conventional sensing schemes suffer from limitations of these parameters. Here we experimentally show a new method called dynamical sensitivity control (DYSCO) that boost the benchmark parameters and thus extends the practical applicability of the NV spin for nanoscale sensing. In contrast to conventional dynamical decoupling schemes, where π pulse trains toggle the spin precession abruptly, the DYSCO method allows for a smooth, analog modulation of the quantum probe's sensitivity. Our method decouples frequency selectivity and spectral resolution unconstrained over the bandwidth (1.85 MHz-392 Hz in our experiments). Using DYSCO we demonstrate high-accuracy NV magnetometry without |2π| ambiguities, an enhancement of the dynamic range by a factor of 4 · 10 3 , and interrogation times exceeding 2 ms in off-the-shelf diamond. In a broader perspective the DYSCO method provides a handle on the inherent dynamics of quantum systems offering decisive advantages for NV centre based applications notably in quantum information and single molecule NMR/MRI.

The precategorical nature of visual short-term memory.

PubMed

Quinlan, Philip T; Cohen, Dale J

2016-11-01

We conducted a series of recognition experiments that assessed whether visual short-term memory (VSTM) is sensitive to shared category membership of to-be-remembered (tbr) images of common objects. In Experiment 1 some of the tbr items shared the same basic level category (e.g., hand axe): Such items were no better retained than others. In the remaining experiments, displays contained different images of items from the same higher-level category (e.g., food: a bagel, a sandwich, a pizza). Evidence from the later experiments did suggest that participants were sensitive to the categorical relations present in the displays. However, when separate measures of sensitivity and bias were computed, the data revealed no effects on sensitivity, but a greater tendency to respond positively to noncategory items relative to items from the depicted category. Across all experiments, there was no evidence that items from a common category were better remembered than unique items. Previous work has shown that principles of perceptual organization do affect the storage and maintenance of tbr items. The present work shows that there are no corresponding conceptual principles of organization in VSTM. It is concluded that the sort of VSTM tapped by single probe recognition methods is precategorical in nature. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Sensitive Immunofluorescent Staining of Cells via Generation of Fluorescent Nanoscale Polymer Films in Response to Biorecognition

PubMed Central

Avens, Heather J.; Berron, Brad J.; May, Allison M.; Voigt, Katerina R.; Seedorf, Gregory J.; Balasubramaniam, Vivek; Bowman, Christopher N.

2011-01-01

Immunofluorescent staining is central to nearly all cell-based research, yet only a few fluorescent signal amplification approaches for cell staining exist, each with distinct limitations. Here, the authors present a novel, fluorescent polymerization-based amplification (FPBA) method that is shown to enable similar signal intensities as the highly sensitive, enzyme-based tyramide signal amplification (TSA) approach. Being non-enzymatic, FPBA is not expected to suffer from nonspecific staining of endogenous enzymes, as occurs with enzyme-based approaches. FPBA employs probes labeled with photopolymerization initiators, which lead to the controlled formation of fluorescent polymer films only at targeted biorecognition sites. Nuclear pore complex proteins (NPCs; in membranes), vimentin (in filaments), and von Willebrand factor (in granules) were all successfully immunostained by FPBA. Also, FPBA was demonstrated to be capable of multicolor immunostaining of multiple antigens. To assess relative sensitivity, decreasing concentrations of anti-NPC antibody were used, indicating that both FPBA and TSA stained NPC down to a 1:100,000 dilution. Nonspecific, cytoplasmic signal resulting from NPC staining was found to be reduced up to 5.5-fold in FPBA as compared to TSA, demonstrating better signal localization with FPBA. FPBA’s unique approach affords a combination of preferred attributes, including high sensitivity and specificity not otherwise available with current techniques. PMID:21339175

Multi-angle nuclear imaging apparatus and method

DOEpatents

Anger, Hal O. [Berkeley, CA

1980-04-08

Nuclear imaging apparatus for obtaining multi-plane readouts of radioactive material in a human or animal subject. A probe disposed in the vicinity of the subject is provided for receiving radiation from radiating sources in the subject and for forming a probe radiation image. The probe has a collimator with different portions thereof having holes disposed at different angles. A single scintillation crystal overlies the collimator for receiving radiation passing through the collimator and producing scintillations to provide the probe image. An array of photomultiplier tubes overlie the single crystal for observing the probe image and providing electrical outputs. Conversion apparatus is provided for converting the electrical outputs representing the probe image into optical images displayed on the screen of a cathode ray tube. Divider apparatus is provided for dividing the probe radiation image into a plurality of areas with the areas corresponding to different portions of the collimator having holes disposed at different angles. A light sensitive medium is provided for receiving optical images. Apparatus is provided for causing relative movement between the probe and the subject. Apparatus is also provided for causing relative movement between the optical image on the screen and the light sensitive medium which corresponds to the relative movement between the probe and the subject whereby there is produced on the light sensitive medium a plurality of images that portray the subject as seen from different angles corresponding to the portions of the collimator having holes at different angles.

Multi-angle nuclear imaging apparatus and method

DOEpatents

Anger, H.O.

1980-04-08

A nuclear imaging apparatus is described for obtaining multi-plane readouts of radioactive material in a human or animal subject. A probe disposed in the vicinity of the subject is provided for receiving radiation from radiating sources in the subject and for forming a probe radiation image. The probe has a collimator with different portions having holes disposed at different angles. A single scintillation crystal overlies the collimator for receiving radiation passing through the collimator and producing scintillations to provide the probe image. An array of photomultiplier tubes overlie the single crystal for observing the probe image and providing electrical outputs. Conversion apparatus is provided for converting the electrical outputs representing the probe image into optical images displayed on the screen of a cathode ray tube. Divider apparatus is provided for dividing the probe radiation image into a plurality of areas with the areas corresponding to different portions of the collimator having holes disposed at different angles. A light sensitive medium is provided for receiving optical images. Apparatus is provided for causing relative movement between the probe and the subject. Apparatus is also provided for causing relative movement between the optical image on the screen and the light sensitive medium which corresponds to the relative movement between the probe and the subject whereby there is produced on the light sensitive medium a plurality of images that portray the subject as seen from different angles corresponding to the portions of the collimator having holes at different angles. 11 figs.

Bunker probe: A plasma potential probe almost insensitive to its orientation with the magnetic field

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

Costea, S., E-mail: stefan.costea@uibk.ac.at; Schneider, B. S.; Schrittwieser, R.

Due to their ability to suppress a large part of the electron current and thus measuring directly the plasma potential, ion sensitive probes have begun to be widely tested and used in fusion devices. For these probes to work, almost perfect alignment with the total magnetic field is necessary. This condition cannot always be fulfilled due to the curvature of magnetic fields, complex magnetic structure, or magnetic field reconnection. In this perspective, we have developed a plasma potential probe (named Bunker probe) based on the principle of the ion sensitive probe but almost insensitive to its orientation with the totalmore » magnetic field. Therefore it can be used to measure the plasma potential inside fusion devices, especially in regions with complex magnetic field topology. Experimental results are presented and compared with Ball-Pen probe measurements taken under identical conditions. We have observed that the floating potential of the Bunker probe is indeed little affected by its orientation with the magnetic field for angles ranging from 90° to 30°, in contrast to the Ball-Pen probe whose floating potential decreases towards that of a Langmuir probe if not properly aligned with the magnetic field.« less

A novel fluorescent probe for rapid and sensitive detection of hydrogen sulfide in living cells

NASA Astrophysics Data System (ADS)

Pan, Jian; Xu, Junchao; Zhang, Youlai; Wang, Liang; Qin, Caiqin; Zeng, Lintao; Zhang, Yue

2016-11-01

A novel fluorescent probe for H2S was developed based on a far-red emitting indole-BODIPY, which was decorated with morpholine and 2,4-dinitrobenzenesulfonyl (DNBS) group. This probe showed rapid response (t1/2 = 3 min), high selectivity and sensitivity for H2S with significant colorimetric and fluorescence OFF-ON signals, which was triggered by cleavage of 2,4-dinitrobenzenesulfonyl group. This probe could quantitatively detect the concentrations of H2S ranging from 0 to 60 μM, and the detection of limit was found to be as low as 26 nM. Cell imaging results indicated that the probe could detect and visualize H2S in the living cells.

Interface-Targeting Strategy Enables Two-Photon Fluorescent Lipid Droplet Probes for High-Fidelity Imaging of Turbid Tissues and Detecting Fatty Liver.

PubMed

Guo, Lifang; Tian, Minggang; Feng, Ruiqing; Zhang, Ge; Zhang, Ruoyao; Li, Xuechen; Liu, Zhiqiang; He, Xiuquan; Sun, Jing Zhi; Yu, Xiaoqiang

2018-04-04

Lipid droplets (LDs) with unique interfacial architecture not only play crucial roles in protecting a cell from lipotoxicity and lipoapoptosis but also closely relate with many diseases such as fatty liver and diabetes. Thus, as one of the important applied biomaterials, fluorescent probes with ultrahigh selectivity for in situ and high-fidelity imaging of LDs in living cells and tissues are critical to elucidate relevant physiological and pathological events as well as detect related diseases. However, available probes only utilizing LDs' waterless neutral cores but ignoring the unique phospholipid monolayer interfaces exhibit low selectivity. They cannot differentiate neutral cores of LDs from intracellular other lipophilic microenvironments, which results in extensively cloud-like background noise and severely limited their bioapplications. Herein, to design LD probes with ultrahigh selectivity, the exceptional interfacial architecture of LDs is considered adequately and thus an interface-targeting strategy is proposed for the first time. According to the novel strategy, we have developed two amphipathic fluorescent probes (N-Cy and N-Py) by introducing different cations into a lipophilic fluorophore (nitrobenzoxadiazole (NBD)). Consequently, their cationic moiety precisely locates the interfaces through electrostatic interaction and simultaneously NBD entirely embeds into the waterless core via hydrophobic interaction. Thus, high-fidelity and background-free fluorescence imaging of LDs are expectably realized in living cells in situ. Moreover, LDs in turbid tissues like skeletal muscle slices have been clearly imaged (up to 82 μm depth) by a two-photon microscope. Importantly, using N-Cy, we not only intuitively monitored the variations of LDs in number, size, and morphology but also clearly revealed their abnormity in hepatic tissues resulting from fatty liver. Therefore, these unique probes provide excellent imaging tools for elucidating LD-related physiological and pathological processes and the interface-targeting strategy possesses universal significance for designing probes with ultrahigh selectivity.

Development of a novel lysosome-targetable time-gated luminescence probe for ratiometric and luminescence lifetime detection of nitric oxide in vivo † †Electronic supplementary information (ESI) available: Experimental details for the syntheses of TRP-Tb3+ and TRP-NO, and supplementary figures. See DOI: 10.1039/c6sc03667h Click here for additional data file.

PubMed Central

Dai, Zhichao; Tian, Lu; Liu, Xiangli

2017-01-01

Rapid, multiplexed, sensitive and specific identification and quantitative detection of nitric oxide (NO) are in great demand in biomedical science. Herein, a novel multifunctional probe based on the intramolecular LRET (luminescence resonance energy transfer) strategy, TRP-NO, was designed for the highly sensitive and selective ratiometric and luminescence lifetime detection of lysosomal NO. Before reaction with NO, the emission of the rhodamine moiety in TRP-NO is switched off, which prevents the LRET process, so that the probe emits only the long-lived Tb3+ luminescence. However, upon reaction with NO, accompanied by the turn-on of rhodamine emission, the LRET from the Tb3+-complex moiety to rhodamine moiety occurs, which results in a remarkable increase of the rhodamine emission and decrease of the Tb3+ emission. After the reaction, the intensity ratio of the rhodamine emission to the Tb3+ emission, I 565/I 540, was found to be 28.8-fold increased, and the dose-dependent enhancement of the I 565/I 540 value showed a good linearity upon the increase of NO concentration. In addition, a dose-dependent luminescence lifetime decrease was distinctly observed between the average luminescence lifetime of the probe and NO concentration, which provides a ∼10-fold contrast window for the detection of NO. These unique properties allowed TRP-NO to be conveniently used as a time-gated luminescence probe for the quantitative detection of NO using both luminescence intensity ratio and luminescence lifetime as signals. The applicability of TRP-NO for ratiometric time-gated luminescence imaging of NO in living cells was investigated. Meanwhile, dye co-localization studies confirmed a quite precise distribution of TRP-NO in lysosomes by confocal microscopy imaging. Furthermore, the practical applicability of TRP-NO was demonstrated by the visualization of NO in Daphnia magna. All of the results demonstrated that TRP-NO could serve as a useful tool for exploiting and elucidating the function of NO at sub-cellular levels with high specificity, accuracy and contrast. PMID:28451312

Fluorinated Paramagnetic Complexes: Sensitive and Responsive Probes for Magnetic Resonance Spectroscopy and Imaging

NASA Astrophysics Data System (ADS)

Peterson, Katie L.; Srivastava, Kriti; Pierre, Valérie C.

2018-05-01

Fluorine magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) of chemical and physiological processes is becoming more widespread. The strength of this technique comes from the negligible background signal in in vivo 19F MRI and the large chemical shift window of 19F that enables it to image concomitantly more than one marker. These same advantages have also been successfully exploited in the design of responsive 19F probes. Part of the recent growth of this technique can be attributed to novel designs of 19F probes with improved imaging parameters due to the incorporation of paramagnetic metal ions. In this review, we provide a description of the theories and strategies that have been employed successfully to improve the sensitivity of 19F probes with paramagnetic metal ions. The Bloch-Wangsness-Redfield theory accurately predicts how molecular parameters such as distance, geometry, rotational correlation times, as well as the nature, oxidation state, and spin state of the metal ion affect the sensitivity of the fluorine-based probes. The principles governing the design of responsive 19F probes are subsequently described in a “how to” guide format. Examples of such probes and their advantages and disadvantages are highlighted through a synopsis of the literature.

Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

PubMed

Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

2015-08-12

Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples.

Kinetic Contributions to Gating by Interactions Unique to N-methyl-d-aspartate (NMDA) Receptors*

PubMed Central

Borschel, William F.; Cummings, Kirstie A.; Tindell, LeeAnn K.; Popescu, Gabriela K.

2015-01-01

Among glutamate-gated channels, NMDA receptors produce currents that subside with unusually slow kinetics, and this feature is essential to the physiology of central excitatory synapses. Relative to the homologous AMPA and kainate receptors, NMDA receptors have additional intersubunit contacts in the ligand binding domain that occur at both conserved and non-conserved sites. We examined GluN1/GluN2A single-channel currents with kinetic analyses and modeling to probe these class-specific intersubunit interactions for their role in glutamate binding and receptor gating. We found that substitutions that eliminate such interactions at non-conserved sites reduced stationary gating, accelerated deactivation, and imparted sensitivity to aniracetam, an AMPA receptor-selective positive modulator. Abolishing unique contacts at conserved sites also reduced stationary gating and accelerated deactivation. These results show that contacts specific to NMDA receptors, which brace the heterodimer interface within the ligand binding domain, stabilize actively gating receptor conformations and result in longer bursts and slower deactivations. They support the view that the strength of the heterodimer interface modulates gating in both NMDA and non-NMDA receptors and that unique interactions at this interface are responsible in part for basic differences between the kinetics of NMDA and non-NMDA currents at glutamatergic synapses. PMID:26370091

Zinc and nitrogen ornamented bluish white luminescent carbon dots for engrossing bacteriostatic activity and Fenton based bio-sensor.

PubMed

Das, Poushali; Ganguly, Sayan; Bose, Madhuparna; Mondal, Subhadip; Choudhary, Sumita; Gangopadhyay, Subhashis; Das, Amit Kumar; Banerjee, Susanta; Das, Narayan Chandra

2018-07-01

Carbon dots with heteroatom co-doping associated with consummate luminescence features are of acute interest in diverse applications such as biomolecule markers, chemical sensing, photovoltaic, and trace element detection. Herein, we demonstrate a straightforward, highly efficient hydrothermal dehydration technique to synthesize zinc and nitrogen co-doped multifunctional carbon dots (N, Zn-CDs) with superior quantum yield (50.8%). The luminescence property of the carbon dots can be tuned by regulating precursor ratio and surface oxidation states in the carbon dots. A unique attribution of the as-prepared carbon dots is the high monodispersity and robust excitation-independent emission behavior that is stable in enormously reactive environment and over a wide range of pH. These N, Zn-CDs unveils captivating bacteriostatic activity against gram-negative bacteria Escherichia coli. Furthermore, the excellent luminescence properties of these carbon dots were applied as a platform of sensitive biosensor for the detection of hydrogen peroxide. Under optimized conditions, these N, Zn-CDs reveals high sensitivity over a broad range of concentrations with an ultra-low limit of detection (LOD) indicating their pronounced prospective as a fluorescent probe for chemical sensing. Overall, the experimental outcomes propose that these zero-dimensional nano-dots could be developed as bacteriostatic agents to control and prevent the persistence and spreading of bacterial infections and as a fluorescent probe for hydrogen peroxide detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluorescent hybridization probes for nucleic acid detection.

PubMed

Guo, Jia; Ju, Jingyue; Turro, Nicholas J

2012-04-01

Due to their high sensitivity and selectivity, minimum interference with living biological systems, and ease of design and synthesis, fluorescent hybridization probes have been widely used to detect nucleic acids both in vivo and in vitro. Molecular beacons (MBs) and binary probes (BPs) are two very important hybridization probes that are designed based on well-established photophysical principles. These probes have shown particular applicability in a variety of studies, such as mRNA tracking, single nucleotide polymorphism (SNP) detection, polymerase chain reaction (PCR) monitoring, and microorganism identification. Molecular beacons are hairpin oligonucleotide probes that present distinctive fluorescent signatures in the presence and absence of their target. Binary probes consist of two fluorescently labeled oligonucleotide strands that can hybridize to adjacent regions of their target and generate distinctive fluorescence signals. These probes have been extensively studied and modified for different applications by modulating their structures or using various combinations of fluorophores, excimer-forming molecules, and metal complexes. This review describes the applicability and advantages of various hybridization probes that utilize novel and creative design to enhance their target detection sensitivity and specificity.

Improved experimental limit on the EDM of 225Ra

NASA Astrophysics Data System (ADS)

Bishof, Michael; Bailey, Kevin; Dietrich, Matthew R.; Greene, John P.; Holt, Roy J.; Kalita, Mukut R.; Korsch, Wolfgang; Lemke, Nathan D.; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Tom P.; Parker, Richard H.; Rabga, Tenzin; Singh, Jaideep T.

2015-10-01

Searches for permanent electric dipole moments (EDMs) in fundamental and composite particles are sensitive probes of beyond-standard-model symmetry violation that could explain the dominance of matter over anti-matter. The 225Ra (t1/2 = 15d, I = 1/2) atom is a particularly attractive system to use for an EDM measurement because its large nuclear octupole deformation, closely spaced ground-state parity doublet, and large atomic mass make 225Ra uniquely sensitive to symmetry-violating interactions in the nuclear medium. We have developed an experiment to measure the EDM of 225Ra and demonstrated the first ``proof-of-principle'' measurement, giving a 95% confidence upper limit of 5E-22 e-cm. After implementing a vacuum upgrade, we have observed nuclear spin coherence after 20 s of free evolution - a factor of ten improvement over our earlier results - and have lowered the 225Ra EDM limit by over an order of magnitude. Upcoming experimental upgrades have the potential to further improve our EDM sensitivity by many orders of magnitude, allowing us to test symmetry violation at an unprecedented level. This work is supported by U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.

Sensing site-specific structural characteristics and chirality using vibrational circular dichroism of isotope labeled peptides.

PubMed

Keiderling, Timothy A

2017-12-01

Isotope labeling has a long history in chemistry as a tool for probing structure, offering enhanced sensitivity, or enabling site selection with a wide range of spectroscopic tools. Chirality sensitive methods such as electronic circular dichroism are global structural tools and have intrinsically low resolution. Consequently, they are generally insensitive to modifications to enhance site selectivity. The use of isotope labeling to modify vibrational spectra with unique resolvable frequency shifts can provide useful site-specific sensitivity, and these methods have been recently more widely expanded in biopolymer studies. While the spectral shifts resulting from changes in isotopic mass can provide resolution of modes from specific parts of the molecule and can allow detection of local change in structure with perturbation, these shifts alone do not directly indicate structure or chirality. With vibrational circular dichroism (VCD), the shifted bands and their resultant sign patterns can be used to indicate local conformations in labeled biopolymers, particularly if multiple labels are used and if their coupling is theoretically modeled. This mini-review discusses selected examples of the use of labeling specific amides in peptides to develop local structural insight with VCD spectra. © 2017 Wiley Periodicals, Inc.

Catalytic Chemistry on Oxide Nanostructures

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

Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek

2016-05-29

Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus onmore » demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.« less

Probe shapes that measure time-averaged streamwise momentum and cross-stream turbulence intensity

NASA Technical Reports Server (NTRS)

Rossow, Vernon J. (Inventor)

1993-01-01

A method and apparatus for directly measuring the time-averaged streamwise momentum in a turbulent stream use a probe which has total head response which varies as the cosine-squared of the angle of incidence. The probe has a nose with a slight indentation on its front face for providing the desired response. The method of making the probe incorporates unique design features. Another probe may be positioned in a side-by-side relationship to the first probe to provide a direct measurement of the total pressure. The difference between the two pressures yields the sum of the squares of the cross-stream components of the turbulence level.

Highly sensitive evanescent wave combination tapered fiber optic fluorosensor for protein detection

NASA Astrophysics Data System (ADS)

Nardone, Vincent; Kapoor, Rakesh

2008-02-01

In this paper we are reporting the development of a highly sensitive evanescent wave combination tapered fiber optic fluorosensor. We have demonstrated detection of 5 pM Bovine Serum Albumin (BSA) protein using these fiber optic sensors. The sensor can be easily adopted for detection of other proteins. Six identical probes were prepared and affinity pure Goat anti-BSA antibodies were immobilized on the probe surface. We could detect signal from all the probes kept in 5 pM to 1 nM BSA solution while no signal was detected from the probes kept in 20 nM labeled ESA solution.

Study of polarization properties of fiber-optics probes with use of a binary phase plate.

PubMed

Alferov, S V; Khonina, S N; Karpeev, S V

2014-04-01

We conduct a theoretical and experimental study of the distribution of the electric field components in the sharp focal domain when rotating a zone plate with a π-phase jump placed in the focused beam. Comparing the theoretical and experimental results for several kinds of near-field probes, an analysis of the polarization sensitivity of different types of metal-coated aperture probes is conducted. It is demonstrated that with increasing diameter of the non-metal-coated tip part there occurs an essential redistribution of sensitivity in favor of the transverse electric field components and an increase of the probe's energy throughput.

Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography

DOE PAGES

Meher, Subhashish; Rojhirunsakool, Tanaporn; Nandwana, Peeyush; ...

2015-04-28

In this study, the analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L1 2-ordered g precipitates to form Ni 3(Al,Cr) precipitates in a Ni-14Al-7Cr(at.%) alloy. Interestingly,more » the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within g precipitates to form (Ni,Al) 3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.« less

Measurement of cell respiration and oxygenation in standard multichannel biochips using phosphorescent O2-sensitive probes.

PubMed

Kondrashina, Alina V; Papkovsky, Dmitri B; Dmitriev, Ruslan I

2013-09-07

Measurement of cell oxygenation and oxygen consumption is useful for studies of cell bioenergetics, metabolism, mitochondrial function, drug toxicity and common pathophysiological conditions. Here we present a new platform for such applications which uses commercial multichannel biochips (μ-slides, Ibidi) and phosphorescent O2 sensitive probes. This platform was evaluated with both extracellular and intracellular O2 probes, several different cell types and treatments including mitochondrial uncoupling and inhibition, depletion of extracellular Ca(2+) and inhibition of V-ATPase and histone deacetylases. The results show that compared to the standard microwell plates currently used, the μ-slide platform provides facile O2 measurements with both suspension and adherent cells, higher sensitivity and reproducibility, and faster measurement time. It also allows re-perfusion and multiple treatments of cells and multi-parametric analyses in conjunction with other probes. Optical measurements are conducted on standard fluorescence readers and microscopes.

Microenvironmental Effect of 2'-O-(1-Pyrenylmethyl)uridine Modified Fluorescent Oligonucleotide Probes on Sensitive and Selective Detection of Target RNA.

PubMed

Imincan, Gülnur; Pei, Fen; Yu, Lijia; Jin, Hongwei; Zhang, Liangren; Yang, Xiaoda; Zhang, Lihe; Tang, XinJing

2016-04-19

2'-O-(1-Pyrenylmethyl)uridine modified oligoribonucleotides provide highly sensitive pyrene fluorescent probes for detecting specific nucleotide mutation of RNA targets. To develop more stable and cost-effective oligonucleotide probes, we investigated the local microenvironmental effects of nearby nucleobases on pyrene fluorescence in duplexes of RNAs and 2'-O-(1-pyrenylmethyl)uridine modified oligonucleotides. By incorporation of deoxyribonucleotides, ribonucleotides, 2'-MeO-nucleotides and 2'-F-nucleotides at both sides of 2'-O-(1-pyrenylmethyl)uridine (U(p)) in oligodeoxynucleotide probes, we synthesized a series of pyrene modified oligonucleotide probes. Their pyrene fluorescence emission spectra indicated that only two proximal nucleotides have a substantial effect on the pyrene fluorescence properties of these oligonucleotide probes hybridized with target RNA with an order of fluorescence sensitivity of 2'-F-nucleotides > 2'-MeO-nucleotides > ribonucleotides ≫ deoxyribonucleotides. While based on circular dichroism spectra, overall helix conformations (either A- or B-form) of the duplexes have marginal effects on the sensitivity of the probes. Instead, the local substitution reflected the propensity of the nucleotide sugar ring to adopt North type conformation and, accordingly, shifted their helix geometry toward a more A-type like conformation in local microenvironments. Thus, higher enhancement of pyrene fluorescence emission favored local A-type helix structures and more polar and hydrophobic environments (F > MeO > OH at 2' substitution) of duplex minor grooves of probes with the target RNA. Further dynamic simulation revealed that local microenvironmental effect of 2'-F-nucleotides or ribonucleotides was enough for pyrene moiety to move out of nucleobases to the minor groove of duplexes; in addition, 2'-F-nucleotide had less effect on π-stack of pyrene-modified uridine with upstream and downstream nucleobases. The present oligonucleotide probes successfully distinguished target RNA from single-mutated RNA analyte during an in vitro assay of RNA synthesis.

Fission Signatures for Nuclear Material Detection

NASA Astrophysics Data System (ADS)

Gozani, Tsahi

2009-06-01

Detection and interdiction of nuclear materials in all forms of transport is one of the most critical security issues facing the United States and the rest of the civilized world. Naturally emitted gamma rays by these materials, while abundant and detectable when unshielded, are low in energy and readily shielded. X-ray radiography is useful in detecting the possible presence of shielding material. Positive detection of concealed nuclear materials requires methods which unequivocally detect specific attributes of the materials. These methods typically involve active interrogation by penetrating radiation of neutrons, photons or other particles. Fortunately, nuclear materials, probed by various types of radiation, yield very unique and often strong signatures. Paramount among them are the detectable fission signatures, namely prompt neutrons and gamma rays, and delayed neutrons gamma rays. Other useful signatures are the nuclear states excited by neutrons, via inelastic scattering, or photons, via nuclear resonance fluorescence and absorption. The signatures are very different in magnitude, level of specificity, ease of excitation and detection, signal to background ratios, etc. For example, delayed neutrons are very unique to the fission process, but are scarce, have low energy, and hence are easily absorbed. Delayed gamma rays are more abundant but "featureless", and have a higher background from natural sources and more importantly, from activation due to the interrogation sources. The prompt fission signatures need to be measured in the presence of the much higher levels of probing radiation. This requires taking special measures to look for the signatures, sometimes leading to a significant sensitivity loss or a complete inability to detect them. Characteristic gamma rays induced in nuclear materials reflecting their nuclear structure, while rather unique, require very high intensity of interrogation radiation and very high resolution in energy and/or time. The trade off of signatures, their means of stimulation, and methods of detection, will be reviewed.

d-PET-controlled “off-on” Polarity-sensitive Probes for Reporting Local Hydrophilicity within Lysosomes

NASA Astrophysics Data System (ADS)

Zhu, Hao; Fan, Jiangli; Mu, Huiying; Zhu, Tao; Zhang, Zhen; Du, Jianjun; Peng, Xiaojun

2016-10-01

Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of “off-on” polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of “off-on” polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers. All these probes showed low fluorescence quantum yields in nonpolar solution but became highly fluorescent in polar media. BP-2, which contains a two-carbon linker and a trimethyl quaternary ammonium, displayed a fluorescence intensity and quantum yield that were both linearly correlated with solvent polarity. In addition, BP-2 exhibited high sensitivity and selectivity for polarity over other environmental factors and a variety of biologically relevant species. BP-2 can be synthesized readily via an unusual Mannich reaction followed by methylation. Using electrochemistry combined with theoretical calculations, we demonstrated that the “off-on” sensing behavior of BP-2 is primarily due to the polarity-dependent donor-excited photoinduced electron transfer (d-PET) effect. Live-cell imaging established that BP-2 enables the detection of local hydrophilicity within lysosomes under conditions of lysosomal dysfunction.

The effect of hybridization-induced secondary structure alterations on RNA detection using backscattering interferometry

PubMed Central

Adams, Nicholas M.; Olmsted, Ian R.; Haselton, Frederick R.; Bornhop, Darryl J.; Wright, David W.

2013-01-01

Backscattering interferometry (BSI) has been used to successfully monitor molecular interactions without labeling and with high sensitivity. These properties suggest that this approach might be useful for detecting biomarkers of infection. In this report, we identify interactions and characteristics of nucleic acid probes that maximize BSI signal upon binding the respiratory syncytial virus nucleocapsid gene RNA biomarker. The number of base pairs formed upon the addition of oligonucleotide probes to a solution containing the viral RNA target correlated with the BSI signal magnitude. Using RNA folding software mfold, we found that the predicted number of unpaired nucleotides in the targeted regions of the RNA sequence generally correlated with BSI sensitivity. We also demonstrated that locked nucleic acid (LNA) probes improved sensitivity approximately 4-fold compared to DNA probes of the same sequence. We attribute this enhancement in BSI performance to the increased A-form character of the LNA:RNA hybrid. A limit of detection of 624 pM, corresponding to ∼105 target molecules, was achieved using nine distinct ∼23-mer DNA probes complementary to regions distributed along the RNA target. Our results indicate that BSI has promise as an effective tool for sensitive RNA detection and provides a road map for further improving detection limits. PMID:23519610

Endoscopic optical coherence tomography with a focus-adjustable probe.

PubMed

Liao, Wenchao; Chen, Tianyuan; Wang, Chengming; Zhang, Wenxin; Peng, Zhangkai; Zhang, Xiao; Ai, Shengnan; Fu, Deyong; Zhou, Tieying; Xue, Ping

2017-10-15

We present a focus-adjustable endoscopic probe for optical coherence tomography (OCT), which is able to acquire images with different focal planes and overcome depth-of-focus limitations by image fusing. The use of a two-way shape-memory-alloy spring enables the probe to adjust working distance over 1.5 mm, providing a large scanning range with high resolution and no sensitivity loss. Equipped with a homemade hollow-core ultrasonic motor, the probe is capable of performing an unobstructed 360 deg field-of-view distal scanning. Both the axial resolution and the best lateral resolution are ∼4  μm, with a sensitivity of 100.3 dB. Spectral-domain OCT imaging of phantom and biological tissues with the probe is also demonstrated.

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.

A new diketopyrrolopyrrole-based probe for sensitive and selective detection of sulfite in aqueous solution

NASA Astrophysics Data System (ADS)

Yang, Xiaofeng; Cui, Yu; Li, Yexin; Zheng, Luyi; Xie, Lijun; Ning, Rui; Liu, Zheng; Lu, Junling; Zhang, Gege; Liu, Chunxiang; Zhang, Guangyou

2015-02-01

A new probe was synthesized by incorporating an α,β -unsaturated ketone to a diketopyrrolopyrrole fluorophore. The probe had exhibited a selective and sensitive response to the sulfite against other thirteen anions and biothiols (Cys, Hcy and GSH), through the nucleophilic addition of sulfite to the alkene of probe with the detection limit of 0.1 μM in HEPES (10 mM, pH 7.4) THF/H2O (1:1, v/v). Meanwhile, it could be easily observed that the probe for sulfite changed from pink to colorless by the naked eye, and from pink to blue under UV lamp after the sulfite was added for 20 min. The NMR and Mass spectral analysis demonstrated the expected addition of sulfite to the Cdbnd C bonds.

Sensitivity of the Enviroscan soil moisture capacitance probe to the presence of artificial macropores

USDA-ARS?s Scientific Manuscript database

Capacitance probes (CP) have been used to measure soil water contents in various applications. Effects of large macropores, cracks and other large heterogeneities within the CP sensitivity volume are sources of concerns related to such applications. The objective of this work was to evaluate the sen...

Low energy probes of PeV scale sfermions

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

Altmannshofer, Wolfgang; Harnik, Roni; Zupan, Jure

2013-11-27

We derive bounds on squark and slepton masses in mini-split supersymmetry scenario using low energy experiments. In this setup gauginos are at the TeV scale, while sfermions are heavier by a loop factor. We cover the most sensitive low energy probes including electric dipole moments (EDMs), meson oscillations and charged lepton flavor violation (LFV) transitions. A leading log resummation of the large logs of gluino to sfermion mass ratio is performed. A sensitivity to PeV squark masses is obtained at present from kaon mixing measurements. A number of observables, including neutron EDMs, mu->e transitions and charmed meson mixing, will startmore » probing sfermion masses in the 100 TeV-1000 TeV range with the projected improvements in the experimental sensitivities. We also discuss the implications of our results for a variety of models that address the flavor hierarchy of quarks and leptons. We find that EDM searches will be a robust probe of models in which fermion masses are generated radiatively, while LFV searches remain sensitive to simple-texture based flavor models.« less

Is Grey Level a Suitable Alternative to Low-Contrast Penetration as a Serial Measure of Sensitivity in Computerised Ultrasound Quality Assurance?

PubMed

Dudley, Nicholas J; Gibson, Nicholas M

2017-02-01

The aim of this study was to test the hypothesis that grey levels are a suitable alternative measure of sensitivity in ultrasound imaging quality assurance, as there are several caveats in the use of penetration depth. In a primary cohort of nine probes, where measurements had been made for 6 to 34 mo, both penetration depth and mean grey level fell below tolerance for six probes; both penetration depth and mean grey level remained within tolerance for three probes. In a secondary cohort where a measurement programme had been in place for a shorter period, grey level and/or penetration depth fell below tolerance in 15 of 66 probes; the sensitivity and specificity of at least 10% loss of grey level in predicting >5% loss in penetration depth were 91% and 93%, respectively. A loss of grey level accompanies a loss of penetration and provides a suitable alternative measure of sensitivity. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

PhylArray: phylogenetic probe design algorithm for microarray.

PubMed

Militon, Cécile; Rimour, Sébastien; Missaoui, Mohieddine; Biderre, Corinne; Barra, Vincent; Hill, David; Moné, Anne; Gagne, Geneviève; Meier, Harald; Peyretaillade, Eric; Peyret, Pierre

2007-10-01

Microbial diversity is still largely unknown in most environments, such as soils. In order to get access to this microbial 'black-box', the development of powerful tools such as microarrays are necessary. However, the reliability of this approach relies on probe efficiency, in particular sensitivity, specificity and explorative power, in order to obtain an image of the microbial communities that is close to reality. We propose a new probe design algorithm that is able to select microarray probes targeting SSU rRNA at any phylogenetic level. This original approach, implemented in a program called 'PhylArray', designs a combination of degenerate and non-degenerate probes for each target taxon. Comparative experimental evaluations indicate that probes designed with PhylArray yield a higher sensitivity and specificity than those designed by conventional approaches. Applying the combined PhyArray/GoArrays strategy helps to optimize the hybridization performance of short probes. Finally, hybridizations with environmental targets have shown that the use of the PhylArray strategy can draw attention to even previously unknown bacteria.

Low-mass dielectrons in pp, p-Pb and Pb-Pb collisions measured by the ALICE Experiment

NASA Astrophysics Data System (ADS)

Vorobyev, Ivan

2018-02-01

Dielectrons produced in ultra-relativistic heavy-ion collisions at the LHC provide a unique probe of the system evolution as they are unperturbed by final-state interactions. The dielectron continuum is extremely rich in physics sources: on top of ordinary Dalitz and resonance decays of pseudoscalar and vector mesons, thermal black-body radiation is of particular interest as it carries information about the temperature of the hot and dense system created in such collisions. The dielectron invariant-mass distribution is furthermore sensitive to medium modifications of the spectral function of short-lived vector mesons that are linked to the potential restoration of chiral symmetry at high temperatures. Correlated electron pairs from semi-leptonic charm and beauty decays provide complementary information about the heavy-quark energy loss.

Persistent luminescence nanothermometers

NASA Astrophysics Data System (ADS)

Martín Rodríguez, Emma; López-Peña, Gabriel; Montes, Eduardo; Lifante, Ginés; García Solé, José; Jaque, Daniel; Diaz-Torres, Luis Armando; Salas, Pedro

2017-08-01

Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20-60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.

Multifrequency acoustics as a probe of mesoscopic blood coagulation dynamics

NASA Astrophysics Data System (ADS)

Ganesan, Adarsh; Rajendran, Gokulnath; Ercole, Ari; Seshia, Ashwin

2016-08-01

Coagulation is a complex enzymatic polymerisation cascade. Disordered coagulation is common in medicine and may be life-threatening yet clinical assays are typically bulky and/or provide an incomplete picture of clot mechanical evolution. We present the adaptation of an in-plane acoustic wave device: quartz crystal microbalance with dissipation at multiple harmonics to determine the time-evolution of mesoscale mechanical properties of clot formation in vitro. This approach is sensitive to changes in surface and bulk clot structure in various models of induced coagulopathy. Furthermore, we are able to show that clot formation at surfaces has different kinetics and mechanical strength to that in the bulk, which may have implications for the design of bioprosthetic materials. The "Multifrequency acoustics" approach thus enables unique capability to portray biological processes concerning blood coagulation.

Accreting Double White Dwarf Binaries: Implications for LISA

NASA Astrophysics Data System (ADS)

Kremer, Kyle; Breivik, Katelyn; Larson, Shane L.; Kalogera, Vassiliki

2017-09-01

We explore the long-term evolution of mass-transferring white dwarf (WD) binaries undergoing both direct-impact and disk accretion and explore implications of such systems to gravitational-wave (GW) astronomy. We cover a broad range of initial component masses and show that these systems, the majority of which lie within the Laser Interferometer Space Antenna (LISA) sensitivity range, exhibit prominent negative orbital frequency evolution (chirp) for a significant fraction of their lifetimes. Using a galactic population synthesis, we predict ˜2700 of these systems will be observable with a negative chirp of 0.1 yr-2 by a space-based GW detector like LISA. We also show that detections of mass-transferring double WD systems by LISA may provide astronomers with unique ways of probing the physics governing close compact object binaries.

U-bent plastic optical fiber based plasmonic biosensor for nucleic acid detection

NASA Astrophysics Data System (ADS)

Gowri, A.; Sai, V. V. R.

2017-05-01

This study presents the development of low cost, rapid and highly sensitive plasmonic sandwich DNA biosensor using U-bent plastic optical fiber (POF) probes with high evanescent wave absorbance sensitivity and gold nanoparticles (AuNP) as labels. Plastic optical fiber (PMMA core and fluorinated polymer as cladding) offer ease in machinability and handling due to which optimum U-bent geometry (with fiber and bend diameter of 0.5 and 1.5 mm respectively) for high sensitivity could be achieved. A sensitive fiber optic DNA biosensor is realized by (i) modifying the PMMA surface using ethylenediamine (EDA) in order to maximize the immobilization of capture oligonucleotides (ONs) and (ii) conjugating probe ONs to AuNP labels of optimum size ( 35 nm) with high extinction coefficient and optimal ON surface density. The sandwich hybridization assay on U-bent POF probes results in increase in optical absorbance through the probe with increase in target ON concentration due to the presence of increased number of AuNPs. The absorbance of light passing through the U-bent probe due to the presence of AuNP labels on its surface as result of sandwich DNA hybridization is measured using a halogen lamp and a fiber optic spectrometer. A picomolar limit of detection of target ON (0.2 pM or 1 pg/ml or 5 attomol in 25 μL) is achieved with this biosensing scheme, indicating its potential for the development of a highly sensitive DNA biosensor.

Sensitive detection of point mutation using exponential strand displacement amplification-based surface enhanced Raman spectroscopy.

PubMed

Huang, Si-Qiang; Hu, Juan; Zhu, Guichi; Zhang, Chun-Yang

2015-03-15

Accurate identification of point mutation is particularly imperative in the field of biomedical research and clinical diagnosis. Here, we develop a sensitive and specific method for point mutation assay using exponential strand displacement amplification (SDA)-based surface enhanced Raman spectroscopy (SERS). In this method, a discriminating probe and a hairpin probe are designed to specifically recognize the sequence of human K-ras gene. In the presence of K-ras mutant target (C→T), the 3'-terminal of discriminating probe and the 5'-terminal of hairpin probe can be ligated to form a SDA template. Subsequently, the 3'-terminal of hairpin probe can function as a primer to initiate the SDA reaction, producing a large amount of triggers. The resultant triggers can further hybridize with the discriminating probes to initiate new rounds of SDA reaction, leading to an exponential amplification reaction. With the addition of capture probe-modified gold nanoparticles (AuNPs) and the Rox-labeled reporter probes, the amplified triggers can be assembled on the surface of AuNPs through the formation of sandwich hybrids of capture probe-trigger-reporter probe, generating a strong Raman signal. While in the presence of K-ras wild-type target (C), neither ligation nor SDA reaction can be initiated and no Raman signal is observed. The proposed method exhibits high sensitivity with a detection limit of 1.4pM and can accurately discriminate as low as 1% variant frequency from the mixture of mutant target and wild-type target. Importantly, this method can be further applied to analyze the mutant target in the spiked HEK293T cell lysate, holding great potential for genetic analysis and disease prognosis. Copyright © 2014 Elsevier B.V. All rights reserved.

Photonic Biosensor Assays to Detect and Distinguish Subspecies of Francisella tularensis

PubMed Central

Cooper, Kristie L.; Bandara, Aloka B.; Wang, Yunmiao; Wang, Anbo; Inzana, Thomas J.

2011-01-01

The application of photonic biosensor assays to diagnose the category-A select agent Francisella tularensis was investigated. Both interferometric and long period fiber grating sensing structures were successfully demonstrated; both these sensors are capable of detecting the optical changes induced by either immunological binding or DNA hybridization. Detection was made possible by the attachment of DNA probes or immunoglobulins (IgG) directly to the fiber surface via layer-by-layer electrostatic self-assembly. An optical fiber biosensor was tested using a standard transmission mode long period fiber grating of length 15 mm and period 260 μm, and coated with the IgG fraction of antiserum to F. tularensis. The IgG was deposited onto the optical fiber surface in a nanostructured film, and the resulting refractive index change was measured using spectroscopic ellipsometry. The presence of F. tularensis was detected from the decrease of peak wavelength caused by binding of specific antigen. Detection and differentiation of F. tularensis subspecies tularensis (type A strain TI0902) and subspecies holarctica (type B strain LVS) was further accomplished using a single-mode multi-cavity fiber Fabry-Perot interferometric sensor. These sensors were prepared by depositing seven polymer bilayers onto the fiber tip followed by attaching one of two DNA probes: (a) a 101-bp probe from the yhhW gene unique to type-A strains, or (b) a 117-bp probe of the lpnA gene, common to both type-A and type-B strains. The yhhW probe was reactive with the type-A, but not the type-B strain. Probe lpnA was reactive with both type-A and type-B strains. Nanogram quantities of the target DNA could be detected, highlighting the sensitivity of this method for DNA detection without the use of PCR. The DNA probe reacted with 100% homologous target DNA, but did not react with sequences containing 2-bp mismatches, indicating the high specificity of the assay. These assays will fill an important void that exists for rapid, culture-free, and field-compatible diagnosis of F. tularensis. PMID:22163782

Revolving Eddy-Current Probe Detects Cracks Near Rivets

NASA Technical Reports Server (NTRS)

Namkung, Min; Wincheski, Buzz; Fulton, James P.; Nath, Shridhar; Simpson, John

1995-01-01

Scanning eddy-current probe in circular pattern increases sensitivity with which probe indicates fatigue cracks and other defects in metal surfaces in vicinity of rivets. Technique devised to facilitate inspection of riveted joints in aircraft. Eddy-current probe in question described in "Electro-magnetic Flaw Detector Is Easier To Use" (LAR-15046).

Highly Sensitive Detection of Target Biomolecules on Cell Surface Using Gold Nanoparticle Conjugated with Aptamer Probe

NASA Astrophysics Data System (ADS)

Kim, Hyonchol; Terazono, Hideyuki; Hayashi, Masahito; Takei, Hiroyuki; Yasuda, Kenji

2012-06-01

A method of gold nanoparticle (Au NP) labeling with backscattered electron (BE) imaging of field emission scanning electron microscopy (FE-SEM) was applied for specific detection of target biomolecules on a cell surface. A single-stranded DNA aptamer, which specifically binds to the target molecule on a human acute lymphoblastic leukemia cell, was conjugated with a 20 nm Au NP and used as a probe to label its target molecule on the cell. The Au NP probe was incubated with the cell, and the interaction was confirmed using BE imaging of FE-SEM through direct counting of the number of Au NPs attached on the target cell surface. Specific Au NP-aptamer probes were observed on a single cell surface and their spatial distributions including submicron-order localizations were also clearly visualized, whereas the nonspecific aptamer probes were not observed on it. The aptamer probe can be potentially dislodged from the cell surface with treatment of nucleases, indicating that Au NP-conjugated aptamer probes can be used as sensitive and reversible probes to label target biomolecules on cells.

A cascade signal amplification strategy for sensitive and label-free DNA detection based on Exo III-catalyzed recycling coupled with rolling circle amplification.

PubMed

Liu, Xingti; Xue, Qingwang; Ding, Yongshun; Zhu, Jing; Wang, Lei; Jiang, Wei

2014-06-07

A sensitive and label-free fluorescence assay for DNA detection has been developed based on cascade signal amplification combining exonuclease III (Exo III)-catalyzed recycling with rolling circle amplification. In this assay, probe DNA hybridized with template DNA was coupled onto magnetic nanoparticles to prepare a magnetic bead-probe (MNB-probe)-template complex. The complex could hybridize with the target DNA, which transformed the protruding 3' terminus of template DNA into a blunt end. Exo III could then digest template DNA, liberating the MNB-probe and target DNA. The intact target DNA then hybridized with other templates and released more MNB-probes. The liberated MNB-probe captured the primer, circular DNA and then initiated the rolling circle amplification (RCA) reaction, realizing a cascade signal amplification. Using this cascade amplification strategy, a sensitive DNA detection method was developed which was superior to many existing Exo III-based signal amplification methods. Moreover, N-methyl mesoporphyrin IX, which had a pronounced structural selectivity for the G-quadruplex, was used to combine with the G-quadruplex RCA products and generate a fluorescence signal, avoiding the need for any fluorophore-label probes. The spike and recovery experiments in a human serum sample indicated that our assay also had great potential for DNA detection in real biological samples.

Hydrogen Epoch of Reionization Array (HERA)

NASA Astrophysics Data System (ADS)

DeBoer, David R.; HERA

2015-01-01

The Hydrogen Epoch of Reionization Arrays (HERA - reionization.org) roadmap uses the unique properties of the neutral hydrogen (HI) 21cm line to probe our cosmic dawn: from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER - eor.berkeley.edu), the US-based Murchison Widefield Array (MWA - mwatelescope.org), and MIT Epoch of Reionization (MITEOR) teams along with the South African SKA-SA, University of KwaZulu Natal and the University of Cambridge Cavendish Laborabory. HERA has recently been awarded a National Science Foundation Mid-Scale Innovation Program grant to begin the next phase.HERA leverages the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of systematics and radio continuum foreground emission some four orders of magnitude brighter. With this understanding, we are now able to remove foregrounds to the limits of our sensitivity, culminating in the first physically meaningful upper limits. A redundant calibration algorithm from MITEOR improves the sensitivity of the approach.Building on this, the next stage of HERA incorporates a 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. HERA will be located in the radio quiet environment of the SKA site in the Karoo region of South Africa (where PAPER is currently located). It will have a sensitivity close to two orders of magnitude better than PAPER and the MWA to ensure a robust detection. With its sensitivity and broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the end of the Dark Ages.This paper will present a summary of the current understanding of the signal characteristics and measurements and describe the funded and planned HERA telescope to be built to detect and characterize the EoR power spectrum.

Highly sensitive low-background fluorescent probes for imaging of nitric oxide in cells and tissues.

PubMed

Zhang, Hui-Xian; Chen, Jian-Bo; Guo, Xiao-Feng; Wang, Hong; Zhang, Hua-Shan

2014-03-18

Small-molecule fluorescent probes in combination with fluorescent microscopy can be a powerful tool to provide real-time detection and high spatiotemporal resolution of transient molecules in cells and bodies. For the design of fluorescent probes for transient molecule imaging, high detection sensitivity is crucial. In this report, two new fluorescent probes, 8-(3,4-diaminophenyl)-4,4-difluoro-4-bora-3a,4a-diaza-di(1,2-dihydro)naphtho[b,g]-s-indacene (DANPBO-H) and 8-(3,4-diaminophenyl)-1,7-dimethyl-4,4-difluoro-4-bora-3a,4a-diaza-di(1,2-dihydro)naphtho[b,g]-s-indacene (DANPBO-M), have been developed for nitric oxide (NO) imaging. The detection sensitivity has been efficiently improved by use of these probes through increasing NO detection signals and decreasing background fluorescence. Fluorescence in the far-red region is enhanced by 400- and 550-fold after reaction with NO is achieved and remains stable for at least 24 h under the irradiation of xenon lamp. Excitation and emission wavelengths longer than 600 nm and excellent intracellular retention of these probes and their NO products create dark background inside and outside cells and tissues. What is more, the excellent intracellular retention of these compounds is obtained by their strong lipophilicity, which is a novel design concept diametrically opposite to the traditional approaches. The high sensitivity and dark background make DANPBO-H and DANPBO-M competitive for NO imaging in cells and tissues. The lipophilicity-based intracellular retention mechanism as a design strategy has great potential in the development of fluorescent probes for bioimaging.

Solvatochromic and Fluorogenic Dyes as Environment-Sensitive Probes: Design and Biological Applications.

PubMed

Klymchenko, Andrey S

2017-02-21

Fluorescent environment-sensitive probes are specially designed dyes that change their fluorescence intensity (fluorogenic dyes) or color (e.g., solvatochromic dyes) in response to change in their microenvironment polarity, viscosity, and molecular order. The studies of the past decade, including those of our group, have shown that these molecules become universal tools in fluorescence sensing and imaging. In fact, any biomolecular interaction or change in biomolecular organization results in modification of the local microenvironment, which can be directly monitored by these types of probes. In this Account, the main examples of environment-sensitive probes are summarized according to their design concepts. Solvatochromic dyes constitute a large class of environment-sensitive probes which change their color in response to polarity. Generally, they are push-pull dyes undergoing intramolecular charge transfer. Emission of their highly polarized excited state shifts to the red in more polar solvents. Excited-state intramolecular proton transfer is the second key concept to design efficient solvatochromic dyes, which respond to the microenvironment by changing relative intensity of the two emissive tautomeric forms. Due to their sensitivity to polarity and hydration, solvatochromic dyes have been successfully applied to biological membranes for studying lipid domains (rafts), apoptosis and endocytosis. As fluorescent labels, solvatochromic dyes can detect practically any type of biomolecular interactions, involving proteins, nucleic acids and biomembranes, because the binding event excludes local water molecules from the interaction site. On the other hand, fluorogenic probes usually exploit intramolecular rotation (conformation change) as a design concept, with molecular rotors being main representatives. These probes were particularly efficient for imaging viscosity and lipid order in biomembranes as well as to light up biomolecular targets, such as antibodies, aptamers and receptors. The emerging concepts to achieve fluorogenic response to the microenvironment include ground-state isomerization, aggregation-caused quenching, and aggregation-induced emission. The ground-state isomerization exploits, for instance, polarity-dependent spiro-lactone formation in silica-rhodamines. The aggregation-caused quenching uses disruption of the self-quenched dimers and nanoassemblies of dyes in less polar environments of lipid membranes and biomolecules. The aggregation-induced emission couples target recognition with formation of highly fluorescent dye aggregates. Overall, solvatochromic and fluorogenic probes enable background-free bioimaging in wash-free conditions as well as quantitative analysis when combined with advanced microscopy, such as fluorescence lifetime (FLIM) and ratiometric imaging. Further development of fluorescent environment-sensitive probes should address some remaining problems: (i) improving their optical properties, especially brightness, photostability, and far-red to near-infrared operating range; (ii) minimizing nonspecific interactions of the probes in biological systems; (iii) their adaptation for advanced microscopies, notably for superresolution and in vivo imaging.

Dimension-sensitive optical responses of electromagnetically induced transparency vapor in a waveguide

NASA Astrophysics Data System (ADS)

Qi Shen, Jian; He, Sailing

2006-12-01

A three-level EIT (electromagnetically induced transparency) vapor is used to manipulate the transparency and absorption properties of the probe light in a waveguide. The most remarkable feature of the present scheme is such that the optical responses resulting from both electromagnetically induced transparency and large spontaneous emission enhancement are very sensitive to the frequency detunings of the probe light as well as to the small changes of the waveguide dimension. The potential applications of the dimension- and dispersion-sensitive EIT responses are discussed, and the sensitivity limits of some waveguide-based sensors, including electric absorption modulator, optical switch, wavelength sensor, and sensitive magnetometer, are analyzed.

“RaMassays”: Synergistic Enhancement of Plasmon-Free Raman Scattering and Mass Spectrometry for Multimodal Analysis of Small Molecules

NASA Astrophysics Data System (ADS)

Alessandri, Ivano; Vassalini, Irene; Bertuzzi, Michela; Bontempi, Nicolò; Memo, Maurizio; Gianoncelli, Alessandra

2016-10-01

SiO2/TiO2 core/shell (T-rex) beads were exploited as “all-in-one” building-block materials to create analytical assays that combine plasmon-free surface enhanced Raman scattering (SERS) and surface assisted laser desorption/ionization (SALDI) mass spectrometry (RaMassays). Such a multi-modal approach relies on the unique optical properties of T-rex beads, which are able to harvest and manage light in both UV and Vis range, making ionization and Raman scattering more efficient. RaMassays were successfully applied to the detection of small (molecular weight, M.W. <400 Da) molecules with a key relevance in biochemistry and pharmaceutical analysis. Caffeine and cocaine were utilized as molecular probes to test the combined SERS/SALDI response of RaMassays, showing excellent sensitivity and reproducibility. The differentiation between amphetamine/ephedrine and theophylline/theobromine couples demonstrated the synergistic reciprocal reinforcement of SERS and SALDI. Finally, the conversion of L-tyrosine in L-DOPA was utilized to probe RaMassays as analytical tools for characterizing reaction intermediates without introducing any spurious effects. RaMassays exhibit important advantages over plasmonic nanoparticles in terms of reproducibility, absence of interference and potential integration in multiplexed devices.

Diffusion tensor optical coherence tomography

NASA Astrophysics Data System (ADS)

Marks, Daniel L.; Blackmon, Richard L.; Oldenburg, Amy L.

2018-01-01

In situ measurements of diffusive particle transport provide insight into tissue architecture, drug delivery, and cellular function. Analogous to diffusion-tensor magnetic resonance imaging (DT-MRI), where the anisotropic diffusion of water molecules is mapped on the millimeter scale to elucidate the fibrous structure of tissue, here we propose diffusion-tensor optical coherence tomography (DT-OCT) for measuring directional diffusivity and flow of optically scattering particles within tissue. Because DT-OCT is sensitive to the sub-resolution motion of Brownian particles as they are constrained by tissue macromolecules, it has the potential to quantify nanoporous anisotropic tissue structure at micrometer resolution as relevant to extracellular matrices, neurons, and capillaries. Here we derive the principles of DT-OCT, relating the detected optical signal from a minimum of six probe beams with the six unique diffusion tensor and three flow vector components. The optimal geometry of the probe beams is determined given a finite numerical aperture, and a high-speed hardware implementation is proposed. Finally, Monte Carlo simulations are employed to assess the ability of the proposed DT-OCT system to quantify anisotropic diffusion of nanoparticles in a collagen matrix, an extracellular constituent that is known to become highly aligned during tumor development.

Advanced electrical current measurements of microdischarges: evidence of sub-critical pulses and ion currents in barrier discharge in air

NASA Astrophysics Data System (ADS)

Synek, Petr; Zemánek, Miroslav; Kudrle, Vít; Hoder, Tomáš

2018-04-01

Electrical current measurements in corona or barrier microdischarges are a challenge as they require both high temporal resolution and a large dynamic range of the current probe used. In this article, we apply a simple self-assembled current probe and compare it to commercial ones. An analysis in the time and frequency domain is carried out. Moreover, an improved methodology is presented, enabling both temporal resolution in sub-nanosecond times and current sensitivity in the order of tens of micro-amperes. Combining this methodology with a high-tech oscilloscope and self-developed software, a unique statistical analysis of currents in volume barrier discharge driven in atmospheric-pressure air is made for over 80 consecutive periods of a 15 kHz applied voltage. We reveal the presence of repetitive sub-critical current pulses and conclude that these can be identified with the discharging of surface charge microdomains. Moreover, extremely low, long-lasting microsecond currents were detected which are caused by ion flow, and are analysed in detail. The statistical behaviour presented gives deeper insight into the discharge physics of these usually undetectable current signals.

Biomedical applications of glyconanoparticles based on quantum dots.

PubMed

Cunha, C R A; Oliveira, A D P R; Firmino, T V C; Tenório, D P L A; Pereira, G; Carvalho, L B; Santos, B S; Correia, M T S; Fontes, A

2018-03-01

Quantum dots (QDs) are outstanding nanomaterials of great interest to life sciences. Their conjugation versatility added to unique optical properties, highlight these nanocrystals as very promising fluorescent probes. Among uncountable new nanosystems, in the last years, QDs conjugated to glycans or lectins have aroused a growing attention and their application as a tool to study biological and functional properties has increased. This review describes the strategies, reported in the literature, to conjugate QDs to lectins or carbohydrates, providing valuable information for the elaboration, improvement, and application of these nanoconjugates. It also presents the main applications of these nanosystems in glycobiology, such as their potential to study microorganisms, the development of diseases such as cancer, as well as to develop biosensors. The development of glyconanoparticles based on QDs emerged in the last decade. Many works reporting the conjugation of QDs with carbohydrates and lectins have been published, using different strategies and reagents. These bioconjugates enabled studies that are very sensitive and specific, with potential to detect and elucidate the glycocode expressed in various normal or pathologic conditions. Produce a quick reference source over the main advances reached in the glyconanotechnology using QDs as fluorescent probes. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluorescence turn-on detection of iodide, iodate and total iodine using fluorescein-5-isothiocyanate-modified gold nanoparticles.

PubMed

Chen, Yi-Ming; Cheng, Tian-Lu; Tseng, Wei-Lung

2009-10-01

Selective turn-on fluorescence detection of I(-) was accomplished using fluorescein isothiocyanate-decorated gold nanoparticles (FITC-AuNPs). FITC molecules, which fluoresce strongly in an alkaline solution, were severely quenched when they were attached to the surface of AuNPs through their isothiocyanate group. Upon the addition of I(-), FITC molecules were detached because of I(-) adsorption on the surface of AuNPs. As a result, released FITC molecules were restored to their original fluorescence intensity. Because I(-) has a higher binding affinity to the surface of Au than do Br(-), Cl(-), or F(-), the FITC-AuNPs obviously have a higher selectivity toward I(-) than toward these other anions. Meanwhile, after IO(3)(-) was reduced to I(-) with ascorbic acid, the detection of IO(3)(-) was successfully achieved using the FITC-AuNPs. Under an optimum pH and AuNP concentration, the lowest detectable concentrations of I(-) and IO(3)(-) using this probe were 10.0 and 50.0 nM, respectively. The FITC-AuNPs provide a number of advantages, including easy preparation, selectivity, sensitivity, and low cost. This unique probe was applied to an analysis of the total iodine in edible salt and seawater.

Structured oligonucleotides for target indexing to allow single-vessel PCR amplification and solid support microarray hybridization

PubMed Central

Girard, Laurie D.; Boissinot, Karel; Peytavi, Régis; Boissinot, Maurice; Bergeron, Michel G.

2014-01-01

The combination of molecular diagnostic technologies is increasingly used to overcome limitations on sensitivity, specificity or multiplexing capabilities, and provide efficient lab-on-chip devices. Two such techniques, PCR amplification and microarray hybridization are used serially to take advantage of the high sensitivity and specificity of the former combined with high multiplexing capacities of the latter. These methods are usually performed in different buffers and reaction chambers. However, these elaborate methods have a high complexity cost related to reagent requirements, liquid storage and the number of reaction chambers to integrate into automated devices. Furthermore, microarray hybridizations have a sequence dependent efficiency not always predictable. In this work, we have developed the concept of a structured oligonucleotide probe which is activated by cleavage from polymerase exonuclease activity. This technology is called SCISSOHR for Structured Cleavage Induced Single-Stranded Oligonucleotide Hybridization Reaction. The SCISSOHR probes enable indexing the target sequence to a tag sequence. The SCISSOHR technology also allows the combination of nucleic acid amplification and microarray hybridization in a single vessel in presence of the PCR buffer only. The SCISSOHR technology uses an amplification probe that is irreversibly modified in presence of the target, releasing a single-stranded DNA tag for microarray hybridization. Each tag is composed of a 3-nucleotidesequence-dependent segment and a unique “target sequence-independent” 14-nucleotide segment allowing for optimal hybridization with minimal cross-hybridization. We evaluated the performance of five (5) PCR buffers to support microarray hybridization, compared to a conventional hybridization buffer. Finally, as a proof of concept, we developed a multiplexed assay for the amplification, detection, and identification of three (3) DNA targets. This new technology will facilitate the design of lab-on-chip microfluidic devices, while also reducing consumable costs. At term, it will allow the cost-effective automation of highly multiplexed assays for detection and identification of genetic targets. PMID:25489607

Structured oligonucleotides for target indexing to allow single-vessel PCR amplification and solid support microarray hybridization.

PubMed

Girard, Laurie D; Boissinot, Karel; Peytavi, Régis; Boissinot, Maurice; Bergeron, Michel G

2015-02-07

The combination of molecular diagnostic technologies is increasingly used to overcome limitations on sensitivity, specificity or multiplexing capabilities, and provide efficient lab-on-chip devices. Two such techniques, PCR amplification and microarray hybridization are used serially to take advantage of the high sensitivity and specificity of the former combined with high multiplexing capacities of the latter. These methods are usually performed in different buffers and reaction chambers. However, these elaborate methods have high complexity and cost related to reagent requirements, liquid storage and the number of reaction chambers to integrate into automated devices. Furthermore, microarray hybridizations have a sequence dependent efficiency not always predictable. In this work, we have developed the concept of a structured oligonucleotide probe which is activated by cleavage from polymerase exonuclease activity. This technology is called SCISSOHR for Structured Cleavage Induced Single-Stranded Oligonucleotide Hybridization Reaction. The SCISSOHR probes enable indexing the target sequence to a tag sequence. The SCISSOHR technology also allows the combination of nucleic acid amplification and microarray hybridization in a single vessel in presence of the PCR buffer only. The SCISSOHR technology uses an amplification probe that is irreversibly modified in presence of the target, releasing a single-stranded DNA tag for microarray hybridization. Each tag is composed of a 3-nucleotide sequence-dependent segment and a unique "target sequence-independent" 14-nucleotide segment allowing for optimal hybridization with minimal cross-hybridization. We evaluated the performance of five (5) PCR buffers to support microarray hybridization, compared to a conventional hybridization buffer. Finally, as a proof of concept, we developed a multiplexed assay for the amplification, detection, and identification of three (3) DNA targets. This new technology will facilitate the design of lab-on-chip microfluidic devices, while also reducing consumable costs. At term, it will allow the cost-effective automation of highly multiplexed assays for detection and identification of genetic targets.

Development of a free-solution SERS-based assay for point-of-care oral cancer biomarker detection using DNA-conjugated gold nanoparticles

NASA Astrophysics Data System (ADS)

Han, Sungyub; Locke, Andrea K.; Oaks, Luke A.; Cheng, Yi-Shing Lisa; Coté, Gerard L.

2018-02-01

It is estimated that the number of new cases of oral cancers worldwide is 529,000 and more than 300,000 deaths each year. The five-year survival rate remains about 50%, and the low survival rate is believed to be due to delayed detection. The primary detection method is through a comprehensive clinical examination by a dentist followed by a biopsy of suspicious lesions. Systematic review and meta-analysis have revealed that clinical examination alone may not be sufficient to cause the clinician to perform a biopsy or refer for biopsy for early detection of OSCC. Therefore, a non-invasive, point-of-Care (POC) detection with high sensitivity and specificity for early detection would be urgently needed, and using salivary biomarkers would be an ideal technology for it. S100 calcium binding protein P (S100P) mRNA presenting in saliva is a potential biomarker for detection of oral cancer. Further, surface enhanced Raman spectroscopy (SERS) has been shown to be a promising POC diagnostic technique. In this research, a SERS-based assay using oligonucleotide strains was developed for the sensitive and rapid detection of S100P. Gold nanoparticles (AuNPs) as a SERS substrate were used for the conjugation with one of two unique 24 base pair oligonucleotides, referred to as left and right DNA probes. A Raman reporter molecule, malachite green isothiocyanate (MGITC), was bound to left-probe-conjugated AuNPs. UV-vis spectroscopy was employed to monitor the conjugation of DNA probes to AuNPs. The hybridization of S100P target to DNA-conjugated AuNPs in sandwich-assay format was confirmed by Raman spectroscopy and shown to yield and R2 of 0.917 across the range of 0-200 nM and a limit of detection of 3 nM.

Photonic Crystal Biosensor with In-Situ Synthesized DNA Probes for Enhanced Sensitivity

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

Hu, Shuren; Zhao, Y.; Retterer, Scott T

2013-01-01

We report on a nearly 8-fold increase in multi-hole defect photonic crystal biosensor response by incorporating in-situ synthesis of DNA probes, as compared to the conventional functionalization method employing pre-synthesized DNA probe immobilization.

A one degree of freedom haptic system to investigate issues in human perception with particular application to probing tissue.

PubMed

Dibble, Edward; Zivanovic, Aleksandar; Davies, Brian

2004-01-01

This paper presents the results of several early studies relating to human haptic perception sensitivity when probing a virtual object. A 1 degree of freedom (DoF) rotary haptic system, that was designed and built for this purpose, is also presented. The experiments were to assess the maximum forces applied in a minimally invasive surgery (MIS) procedure, quantify the compliance sensitivity threshold when probing virtual tissue and identify the haptic system loop rate necessary for haptic feedback to feel realistic.

Comparison of the Gen-Probe Aptima HIV-1 and Abbott HIV-1 qualitative assays with the Roche Amplicor HIV-1 DNA assay for early infant diagnosis using dried blood spots.

PubMed

Nelson, Julie A E; Hawkins, J Tyler; Schanz, Maria; Mollan, Katie; Miller, Melissa B; Schmitz, John L; Fiscus, Susan A

2014-08-01

The current gold standard for infant diagnosis of HIV-1 is the Roche Amplicor Qualitative DNA assay, but it is being phased out. Compare the Abbott qualitative assay and the Gen-Probe Aptima assay to the gold standard Roche DNA assay using dried blood spots (DBS). The Gen-Probe Aptima and Abbott qualitative HIV-1 assays were compared to the Roche DNA assay for early infant diagnosis. Specificity and sensitivity were determined for the three assays using DBS from 50 HIV-exposed uninfected infants and 269 HIV-1 infected adults from North Carolina, respectively. All of the negative and 151 of the positive DBS had valid results on the 3 different assays, and an additional 118 positive DBS had valid results on the Roche DNA and Aptima assays. All three assays were very specific. The Roche DNA assay was the most sensitive (96.7%) over a wide range of HIV PVL, including samples with PVL<400 copies/ml. Restricted to samples with PVL>400 copies/ml, the Gen-Probe Aptima assay had sensitivity (96.5%) comparable to the Roche DNA assay (98.8%). The Abbott Qualitative assay was the least sensitive and only had sensitivity above 95% among samples with PVL over 1000 copies/ml. The Abbott HIV-1 Qualitative assay was not as sensitive as the comparator assays, so it would not be a useful replacement assay, especially for infants taking antiretroviral prophylaxis. The Gen-Probe Aptima assay is an adequate replacement option for infant diagnosis using DBS. Copyright © 2014 Elsevier B.V. All rights reserved.

Space pruning monotonic search for the non-unique probe selection problem.

PubMed

Pappalardo, Elisa; Ozkok, Beyza Ahlatcioglu; Pardalos, Panos M

2014-01-01

Identification of targets, generally viruses or bacteria, in a biological sample is a relevant problem in medicine. Biologists can use hybridisation experiments to determine whether a specific DNA fragment, that represents the virus, is presented in a DNA solution. A probe is a segment of DNA or RNA, labelled with a radioactive isotope, dye or enzyme, used to find a specific target sequence on a DNA molecule by hybridisation. Selecting unique probes through hybridisation experiments is a difficult task, especially when targets have a high degree of similarity, for instance in a case of closely related viruses. After preliminary experiments, performed by a canonical Monte Carlo method with Heuristic Reduction (MCHR), a new combinatorial optimisation approach, the Space Pruning Monotonic Search (SPMS) method, is introduced. The experiments show that SPMS provides high quality solutions and outperforms the current state-of-the-art algorithms.

[Multiplex real-time PCR method for rapid detection of Marburg virus and Ebola virus].

PubMed

Yang, Yu; Bai, Lin; Hu, Kong-Xin; Yang, Zhi-Hong; Hu, Jian-Ping; Wang, Jing

2012-08-01

Marburg virus and Ebola virus are acute infections with high case fatality rates. A rapid, sensitive detection method was established to detect Marburg virus and Ebola virus by multiplex real-time fluorescence quantitative PCR. Designing primers and Taqman probes from highly conserved sequences of Marburg virus and Ebola virus through whole genome sequences alignment, Taqman probes labeled by FAM and Texas Red, the sensitivity of the multiplex real-time quantitative PCR assay was optimized by evaluating the different concentrations of primers and Probes. We have developed a real-time PCR method with the sensitivity of 30.5 copies/microl for Marburg virus positive plasmid and 28.6 copies/microl for Ebola virus positive plasmids, Japanese encephalitis virus, Yellow fever virus, Dengue virus were using to examine the specificity. The Multiplex real-time PCR assays provide a sensitive, reliable and efficient method to detect Marburg virus and Ebola virus simultaneously.

Study of entry and landing probes for exploration of Titan

NASA Technical Reports Server (NTRS)

1979-01-01

Saturn's largest moon, Titan, is a totally unique planetary body which is certain to yield exciting new phenomena. Current information is lacking in detail to distinguish between a thin methane rich atmosphere and a thick nitrogen rich atmosphere. Therefore, both the thin and thick atmospheric models were used for the study of various Titan probe classes described in this report. The technical requirements, conceptual design, science return, schedule, cost and mission implications of three probe classes that could be used for exploration of Titan are defined. The three probe classes were based on a wide range of exploration mission possibilities.

Scientific Value of a Saturn Atmospheric Probe Mission

NASA Technical Reports Server (NTRS)

Simon-Miller, A. A.; Lunine, J. I.; Atreya, S. K.; Spilker, T. R.; Coustenis, A.; Atkinson, D. H.

2012-01-01

Atmospheric entry probe mISSions to the giant planets can uniquely discriminate between competing theories of solar system formation and the origin and evolution of the giant planets and their atmospheres. This provides for important comparative studies of the gas and ice giants, and to provide a laboratory for studying the atmospheric chemistries, dynamics, and interiors of all the planets including Earth. The giant planets also represent a valuable link to extrasolar planetary systems. As outlined in the recent Planetary Decadal Survey, a Saturn Probe mission - with a shallow probe - ranks as a high priority for a New Frontiers class mission [1].

An intramolecular crossed-benzoin reaction based KCN fluorescent probe in aqueous and biological environments.

PubMed

Lee, Jae Hong; Jang, Joo Hee; Velusamy, Nithya; Jung, Hyo Sung; Bhuniya, Sankarprasad; Kim, Jong Seung

2015-05-04

A turn-on fluorescent probe was designed for selective cyanide anion sensing in aqueous and biological environments. The probe underwent an intramolecular crossed-benzoin reaction in the presence of KCN to expel the fluorophore resorufin. This probe was sensitive to KCN concentrations as low as 4 nM in aqueous media.

Orderly arranged fluorescence dyes as a highly efficient chemiluminescence resonance energy transfer probe for peroxynitrite.

PubMed

Wang, Zhihua; Teng, Xu; Lu, Chao

2015-03-17

Chemiluminescence (CL) probes for reactive oxygen species (ROS) are commonly based on a redox reaction between a CL reagent and ROS, leading to poor selectivity toward a specific ROS. The energy-matching rules in the chemiluminescence resonance energy transfer (CRET) process between a specific ROS donor and a suitable fluorescence dye acceptor is a promising method for the selective detection of ROS. Nevertheless, higher concentrations of fluorescence dyes can lead to the intractable aggregation-caused quenching effect, decreasing the CRET efficiency. In this report, we fabricated an orderly arranged structure of calcein-sodium dodecyl sulfate (SDS) molecules to improve the CRET efficiency between ONOOH* donor and calcein acceptor. Such orderly arranged calcein-SDS composites can distinguish peroxynitrite (ONOO(-)) from a variety of other ROS owing to the energy matching in the CRET process between ONOOH* donor and calcein acceptor. Under the optimal experimental conditions, ONOO(-) could be assayed in the range of 1.0-20.0 μM, and the detection limit for ONOO(-) [signal-to-noise ratio (S/N) = 3] was 0.3 μM. The proposed strategy has been successfully applied in both detecting ONOO(-) in cancer mouse plasma samples and monitoring the generation of ONOO(-) from 3-morpholinosydnonimine (SIN-1). Recoveries from cancer mouse plasma samples were in the range of 96-105%. The success of this work provides a unique opportunity to develop a CL tool to monitor ONOO(-) with high selectivity in a specific manner. Improvement of selectivity and sensitivity of CL probes holds great promise as a strategy for developing a wide range of probes for various ROS by tuning the types of fluorescence dyes.

Noninvasive Synchrotron-Based X-ray Raman Scattering Discriminates Carbonaceous Compounds in Ancient and Historical Materials [ In situ synchrotron-based X-Ray Raman scattering discriminates carbonaceous compounds in ancient and historical materials

DOE PAGES

Gueriau, Pierre; Rueff, Jean -Pascal; Bernard, Sylvain; ...

2017-09-13

Carbon compounds are ubiquitous and occur in a diversity of chemical forms in many systems including ancient and historic materials ranging from cultural heritage to paleontology. Determining their speciation cannot only provide unique information on their origin but may also elucidate degradation processes. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge (280–350 eV) is a very powerful method to probe carbon speciation. However, the short penetration depth of soft X-rays imposes stringent constraints on sample type, preparation, and analytical environment. A hard X-ray probe such as X-ray Raman scattering (XRS) can overcome many of these difficulties. Heremore » we report the use of XRS at ~6 keV incident energy to collect carbon K-edge XANES data and probe the speciation of organic carbon in several specimens relevant to cultural heritage and natural history. This methodology enables the measurement to be done in a nondestructive way, in air, and provides information that is not compromised by surface contamination by ensuring that the dominant signal contribution is from the bulk of the probed material. Using the backscattering geometry at large photon momentum transfer maximizes the XRS signal at the given X-ray energy and enhances nondipole contributions compared to conventional XANES, thereby augmenting the speciation sensitivity. The capabilities and limitations of the technique are discussed. As a result, we show that despite its small cross section, for a range of systems the XRS method can provide satisfactory signals at realistic experimental conditions. XRS constitutes a powerful complement to FT-IR, Raman, and conventional XANES spectroscopy, overcoming some of the limitations of these techniques.« less

Rapid detection of rRNA group I pseudomonads in contaminated metalworking fluids and biofilm formation by fluorescent in situ hybridization.

PubMed

Saha, Ratul; Donofrio, Robert S; Goeres, Darla M; Bagley, Susan T

2012-05-01

Metalworking fluids (MWFs), used in different machining operations, are highly prone to microbial degradation. Microbial communities present in MWFs lead to biofilm formation in the MWF systems, which act as a continuous source of contamination. Species of rRNA group I Pseudomonas dominate in contaminated MWFs. However, their actual distribution is typically underestimated when using standard culturing techniques as most fail to grow on the commonly used Pseudomonas Isolation Agar. To overcome this, fluorescent in situ hybridization (FISH) was used to study their abundance along with biofilm formation by two species recovered from MWFs, Pseudomonas fluorescens MWF-1 and the newly described Pseudomonas oleovorans subsp. lubricantis. Based on 16S rRNA sequences, a unique fluorescent molecular probe (Pseudo120) was designed targeting a conserved signature sequence common to all rRNA group I Pseudomonas. The specificity of the probe was evaluated using hybridization experiments with whole cells of different Pseudomonas species. The probe's sensitivity was determined to be 10(3) cells/ml. It successfully detected and enumerated the abundance and distribution of Pseudomonas indicating levels between 3.2 (± 1.1) × 10(6) and 5.0 (± 2.3) × 10(6) cells/ml in four different industrial MWF samples collected from three different locations. Biofilm formation was visualized under stagnant conditions using high and low concentrations of cells for both P. fluorescens MWF-1 and P. oleovorans subsp. lubricantis stained with methylene blue and Pseudo120. On the basis of these observations, this molecular probe can be successfully be used in the management of MWF systems to monitor the levels and biofilm formation of rRNA group I pseudomonads.

Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates

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

Kovalev, S.; Green, B.; Golz, T.

Here, understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systemsmore » and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.« less

Characterization of two nisin-producing Lactococcus lactis subsp. lactis strains isolated from a commercial sauerkraut fermentation.

PubMed Central

Harris, L J; Fleming, H P; Klaenhammer, T R

1992-01-01

Two Lactococcus lactis subsp. lactis strains, NCK400 and LJH80, isolated from a commercial sauerkraut fermentation were shown to produce nisin. LJH80 was morphologically unstable and gave rise to two stable, nisin-producing (Nip+) derivatives, NCK318-2 and NCK318-3. NCK400 and derivatives of LJH80 exhibited identical morphological and metabolic characteristics, but could be distinguished on the basis of plasmid profiles and genomic hybridization patterns to a DNA probe specific for the iso-ISS1 element, IS946. NCK318-2 and NCK318-3 harbored two and three plasmids, respectively, which hybridized with IS946. Plasmid DNA was not detected in NCK400, and DNA from this strain failed to hybridize with IS946. Despite the absence of detectable plasmid DNA in NCK400, nisin-negative derivatives (NCK402 and NCK403) were isolated after repeated transfer in broth at 37 degrees C. Nisin-negative derivatives concurrently lost the ability to ferment sucrose and became sensitive to nisin. A 4-kbp HindIII fragment containing the structural gene for nisin (spaN), cloned from L. lactis subsp. lactis ATCC 11454, was used to probe genomic DNA of NCK318-2, NCK318-3, NCK400, and NCK402 digested with EcoRI or HindIII. The spaN probe hybridized to an 8.8-kbp EcoRI fragment and a 10-kbp HindIII fragment in the Nip+ sauerkraut isolates, but did not hybridize to the Nip- derivative, NCK402. A different hybridization pattern was observed when the same probe was used against Nip+ L. lactis subsp. lactis ATCC 11454 and ATCC 7962. These phenotypic and genetic data confirmed that unique Nip+ L. lactis subsp. lactis strains were isolated from fermenting sauerkraut. Images PMID:1622214

A universal fluorogenic switch for Fe(ii) ion based on N-oxide chemistry permits the visualization of intracellular redox equilibrium shift towards labile iron in hypoxic tumor cells.

PubMed

Hirayama, Tasuku; Tsuboi, Hitomi; Niwa, Masato; Miki, Ayaji; Kadota, Satoki; Ikeshita, Yukie; Okuda, Kensuke; Nagasawa, Hideko

2017-07-01

Iron (Fe) species play a number of biologically and pathologically important roles. In particular, iron is a key element in oxygen sensing in living tissue where its metabolism is intimately linked with oxygen metabolism. Regulation of redox balance of labile iron species to prevent the generation of iron-catalyzed reactive oxygen species (ROS) is critical to survival. However, studies on the redox homeostasis of iron species are challenging because of a lack of a redox-state-specific detection method for iron, in particular, labile Fe 2+ . In this study, a universal fluorogenic switching system is established, which is responsive to Fe 2+ ion based on a unique N-oxide chemistry in which dialkylarylamine N-oxide is selectively deoxygenized by Fe 2+ to generate various fluorescent probes of Fe 2+ -CoNox-1 (blue), FluNox-1 (green), and SiRhoNox-1 (red). All the probes exhibited fluorescence enhancement against Fe 2+ with high selectivity both in cuvette and in living cells. Among the probes, SiRhoNox-1 showed an excellent fluorescence response with respect to both reaction rate and off/on signal contrast. Imaging studies were performed showing the intracellular redox equilibrium shift towards labile iron in response to reduced oxygen tension in living cells and 3D tumor spheroids using SiRhoNox-1, and it was found that the hypoxia induction of labile Fe 2+ is independent of iron uptake, hypoxia-induced signaling, and hypoxia-activated enzymes. The present studies demonstrate the feasibility of developing sensitive and specific fluorescent probes for Fe 2+ with refined photophysical characteristics that enable their broad application in the study of iron in various physiological and pathological conditions.

Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates

DOE PAGES

Kovalev, S.; Green, B.; Golz, T.; ...

2017-03-06

Here, understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systemsmore » and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms). Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.« less

Pump-probe nonlinear phase dispersion spectroscopy.

PubMed

Robles, Francisco E; Samineni, Prathyush; Wilson, Jesse W; Warren, Warren S

2013-04-22

Pump-probe microscopy is an imaging technique that delivers molecular contrast of pigmented samples. Here, we introduce pump-probe nonlinear phase dispersion spectroscopy (PP-NLDS), a method that leverages pump-probe microscopy and spectral-domain interferometry to ascertain information from dispersive and resonant nonlinear effects. PP-NLDS extends the information content to four dimensions (phase, amplitude, wavelength, and pump-probe time-delay) that yield unique insight into a wider range of nonlinear interactions compared to conventional methods. This results in the ability to provide highly specific molecular contrast of pigmented and non-pigmented samples. A theoretical framework is described, and experimental results and simulations illustrate the potential of this method. Implications for biomedical imaging are discussed.

Pump-probe nonlinear phase dispersion spectroscopy

PubMed Central

Robles, Francisco E.; Samineni, Prathyush; Wilson, Jesse W.; Warren, Warren S.

2013-01-01

Pump-probe microscopy is an imaging technique that delivers molecular contrast of pigmented samples. Here, we introduce pump-probe nonlinear phase dispersion spectroscopy (PP-NLDS), a method that leverages pump-probe microscopy and spectral-domain interferometry to ascertain information from dispersive and resonant nonlinear effects. PP-NLDS extends the information content to four dimensions (phase, amplitude, wavelength, and pump-probe time-delay) that yield unique insight into a wider range of nonlinear interactions compared to conventional methods. This results in the ability to provide highly specific molecular contrast of pigmented and non-pigmented samples. A theoretical framework is described, and experimental results and simulations illustrate the potential of this method. Implications for biomedical imaging are discussed. PMID:23609646

Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

NASA Astrophysics Data System (ADS)

Zhang, Xiaofei; Ye, Xuan; Li, Xide

2016-08-01

In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

PubMed

Ye, Yu-Dan; Xia, Li; Xu, Dang-Dang; Xing, Xiao-Jing; Pang, Dai-Wen; Tang, Hong-Wu

2016-11-15

Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Quasar Astrophysics with the Space Interferometry Mission

NASA Technical Reports Server (NTRS)

Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn

2007-01-01

Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.

Development of oligonucleotide microarrays for simultaneous multi-species identification of Phellinus tree-pathogenic fungi.

PubMed

Tzean, Yuh; Shu, Po-Yao; Liou, Ruey-Fen; Tzean, Shean-Shong

2016-03-01

Polyporoid Phellinus fungi are ubiquitously present in the environment and play an important role in shaping forest ecology. Several species of Phellinus are notorious pathogens that can affect a broad variety of tree species in forest, plantation, orchard and urban habitats; however, current detection methods are overly complex and lack the sensitivity required to identify these pathogens at the species level in a timely fashion for effective infestation control. Here, we describe eight oligonucleotide microarray platforms for the simultaneous and specific detection of 17 important Phellinus species, using probes generated from the internal transcribed spacer regions unique to each species. The sensitivity, robustness and efficiency of this Phellinus microarray system was subsequently confirmed against template DNA from two key Phellinus species, as well as field samples collected from tree roots, trunks and surrounding soil. This system can provide early, specific and convenient detection of Phellinus species for forestry, arboriculture and quarantine inspection, and could potentially help to mitigate the environmental and economic impact of Phellinus-related diseases. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Self-locked aptamer probe mediated cascade amplification strategy for highly sensitive and selective detection of protein and small molecule.

PubMed

Li, Wei; Jiang, Wei; Wang, Lei

2016-10-12

In this work, a novel self-locked aptamer probe mediated cascade amplification strategy has been constructed for highly sensitive and specific detection of protein. First, the self-locked aptamer probe was designed with three functions: one was specific molecular recognition attributed to the aptamer sequence, the second was signal transduction owing to the transduction sequence, and the third was self-locking through the hybridization of the transduction sequence and part of the aptamer sequence. Then, the aptamer sequence specific recognized the target and folded into a three-way helix junction, leading to the release of the transduction sequence. Next, the 3'-end of this three-way junction acted as primer to trigger the strand displacement amplification (SDA), yielding a large amount of primers. Finally, the primers initiated the dual-exponential rolling circle amplification (DE-RCA) and generated numerous G-quadruples sequences. By inserting the fluorescent dye N-methyl mesoporphyrin IX (NMM), enhanced fluorescence signal was achieved. In this strategy, the self-locked aptamer probe was more stable to reduce the interference signals generated by the uncontrollable folding in unbounded state. Through the cascade amplification of SDA and DE-RCA, the sensitivity was further improved with a detection limit of 3.8 × 10(-16) mol/L for protein detection. Furthermore, by changing the aptamer sequence of the probe, sensitive and selective detection of adenosine has been also achieved, suggesting that the proposed strategy has good versatility and can be widely used in sensitive and selective detection of biomolecules. Copyright © 2016 Elsevier B.V. All rights reserved.

Photoacoustic Imaging with a Commercial Ultrasound System and a Custom Probe

PubMed Central

Wang, Xueding; Fowlkes, J. Brian; Cannata, Jonathan M.; Hu, Changhong; Carson, Paul L.

2010-01-01

Building photoacoustic imaging (PAI) systems by using stand-alone ultrasound (US) units makes it convenient to take advantage of the state-of-the-art ultrasonic technologies. However, the sometimes limited receiving sensitivity and the comparatively narrow bandwidth of commercial US probes may not be sufficient to acquire high quality photoacoustic images. In this work, a high-speed PAI system has been developed using a commercial US unit and a custom built 128-element piezoelectric-polymer array (PPA) probe using a P(VDF-TrFE) film and flexible circuit to define the elements. Since the US unit supports simultaneous signal acquisition from 64 parallel receive channels, PAI data for synthetic image formation from a 64 or 128 element array aperture can be acquired after a single or dual laser firing, respectively. Therefore, 2D B-scan imaging can be achieved with a maximum frame rate up to 10 Hz, limited only by the laser repetition rate. The uniquely properties of P(VDF-TrFE) facilitated a wide -6 dB receiving bandwidth of over 120 % for the array. A specially designed 128-channel preamplifier board made the connection between the array and the system cable which not only enabled element electrical impedance matching but also further elevated the signal-to-noise ratio (SNR) to further enhance the detection of weak photoacoustic signals. Through the experiments on phantoms and rabbit ears, the good performance of this PAI system was demonstrated. PMID:21276653

A novel electrochemical cytosensor for selective and highly sensitive detection of cancer cells using binding-induced dual catalytic hairpin assembly.

PubMed

Zhang, Ye; Luo, Shihua; Situ, Bo; Chai, Zhixin; Li, Bo; Liu, Jumei; Zheng, Lei

2018-04-15

Rare cancer cells in body fluid could be useful biomarkers for noninvasive diagnosis of cancer. However, detection of these rare cells is currently challenging. In this work, a binding-induced dual catalytic hairpin assembly (DCHA) electrochemical cytosensor was developed for highly selective and sensitive detection of cancer cells. The fuel probe, released by hybridization between the capture probe and catalytic hairpin assembly (CHA) products of target cell-responsive reaction, initiated dual CHA recycling, leading to multiple CHA products. Furthermore, the hybridization between fuel probe and capture probe decreased non-specific CHA products, improving the signal-to-noise ratio and detection sensitivity. Under the optimal conditions, the developed cytosensor was able to detect cells down to 30 cells mL -1 (S/N = 3) with a linear range from 50 to 100,000 cells mL -1 and was capable of distinguishing target cells from normal cells in clinical blood samples. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel pH sensitive water soluble fluorescent nanomicellar sensor for potential biomedical applications.

PubMed

Georgiev, Nikolai I; Bryaskova, Rayna; Tzoneva, Rumiana; Ugrinova, Iva; Detrembleur, Christophe; Miloshev, Stoyan; Asiri, Abdullah M; Qusti, Abdullah H; Bojinov, Vladimir B

2013-11-01

Herein we report on the synthesis and sensor activity of a novel pH sensitive probe designed as highly water-soluble fluorescent micelles by grafting of 1,8-naphthalimide-rhodamine bichromophoric FRET system (RNI) to the PMMA block of a well-defined amphiphilic diblock copolymer-poly(methyl methacrylate)-b-poly(methacrylic acid) (PMMA48-b-PMAA27). The RNI-PMMA48-b-PMAA27 adduct is capable of self-assembling into micelles with a hydrophobic PMMA core, containing the anchored fluorescent probe, and a hydrophilic shell composed of PMAA block. Novel fluorescent micelles are able to serve as a highly sensitive pH probe in water and to internalize successfully HeLa and HEK cells. Furthermore, they showed cell specificity and significantly higher photostability than that of a pure organic dye label such as BODIPY. The valuable properties of the newly prepared fluorescent micelles indicate the high potential of the probe for future biological and biomedical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of scanning graphene Hall probes for magnetic microscopy

NASA Astrophysics Data System (ADS)

Schaefer, Brian T.; Wang, Lei; McEuen, Paul L.; Nowack, Katja C.

We discuss our progress on developing scanning Hall probes fabricated from hexagonal boron nitride (hBN)-encapsulated graphene, with the goal to image magnetic fields with submicron resolution. In contrast to scanning superconducting quantum interference device (SQUID) microscopy, this technique is compatible with a large applied magnetic field and not limited to cryogenic temperatures. The field sensitivity of a Hall probe depends inversely on carrier density, while the primary source of noise in the measurement is Johnson noise originating from the device resistance. hBN-encapsulated graphene demonstrates high carrier mobility at low carrier densities, therefore making it an ideal material for sensitive Hall probes. Furthermore, engineering the dielectric environment of graphene by encapsulating in hBN reduces low-frequency charge noise and disorder from the substrate. We outline our plans for adapting these devices for scanning, including characterization of the point spread function with a scanned current loop and fabrication of a deep-etched structure that enables positioning the sensitive area within 100 nanometers of the sample surface.

MgF2 prism/rhodium/graphene: efficient refractive index sensing structure in optical domain

NASA Astrophysics Data System (ADS)

Mishra, Akhilesh Kumar; Mishra, Satyendra Kumar

2017-04-01

A theoretical study of a noble surface plasmon resonance (SPR) based sensing probe has been carried out. The sensing probe consists of a magnesium fluoride (MgF2) prism with its base coated with rarely used noble metal rhodium (Rh) and a bio-compatible layer of graphene. The refractive indices (RIs) of the sensing medium vary from 1.33 to 1.36 refractive index unit (RIU). The thickness of Rh and the number of graphene layers have been optimized for maximum sensitivity in a constraint set by the detection accuracy (DA). For the operating wavelength of 632 nm, the optimized sensing probe Rh (12 nm)/graphene (single layer) demonstrates sensitivity of ~259 degree/RIU with corresponding DA of ~0.32 degree-1 while for 532 nm of excitation, the optimized sensing probe Rh (12 nm)/graphene (three layer) exhibits sensitivity of ~240 degree/RIU and DA of ~0.27 degree-1.

MgF2 prism/rhodium/graphene: efficient refractive index sensing structure in optical domain.

PubMed

Mishra, Akhilesh Kumar; Mishra, Satyendra Kumar

2017-04-12

A theoretical study of a noble surface plasmon resonance (SPR) based sensing probe has been carried out. The sensing probe consists of a magnesium fluoride (MgF 2 ) prism with its base coated with rarely used noble metal rhodium (Rh) and a bio-compatible layer of graphene. The refractive indices (RIs) of the sensing medium vary from 1.33 to 1.36 refractive index unit (RIU). The thickness of Rh and the number of graphene layers have been optimized for maximum sensitivity in a constraint set by the detection accuracy (DA). For the operating wavelength of 632 nm, the optimized sensing probe Rh (12 nm)/graphene (single layer) demonstrates sensitivity of ~259 degree/RIU with corresponding DA of ~0.32 degree -1 while for 532 nm of excitation, the optimized sensing probe Rh (12 nm)/graphene (three layer) exhibits sensitivity of ~240 degree/RIU and DA of ~0.27 degree -1 .

Probe beam deflection technique as acoustic emission directionality sensor with photoacoustic emission source.

PubMed

Barnes, Ronald A; Maswadi, Saher; Glickman, Randolph; Shadaram, Mehdi

2014-01-20

The goal of this paper is to demonstrate the unique capability of measuring the vector or angular information of propagating acoustic waves using an optical sensor. Acoustic waves were generated using photoacoustic interaction and detected by the probe beam deflection technique. Experiments and simulations were performed to study the interaction of acoustic emissions with an optical sensor in a coupling medium. The simulated results predict the probe beam and wavefront interaction and produced simulated signals that are verified by experiment.

Three-dimensional Analysis of Nanomaterials by Scanning Probe Nanotomography

NASA Astrophysics Data System (ADS)

Efimov, Anton E.; Agapova, Olga I.; Mochalov, Konstantin E.; Agapov, Igor I.

Micro and nanostructure of scaffolds made from fibroin of Bombyx mori silkworm by salt leaching technique was studied by scanning probe nanotomography. Nanopores with dimensions in range from 30 to 180 nm are observed in the scaffold volume. Three - dimensional analysis of obtained data shows that degree of scaffold nanoporosity is 0.5% and nanopores are not interconnected with each other. Usage of scanning probe nanotomography technique enables to obtain unique nanoscale information of 3D structure of biopolymer nanomaterials.

nuID: a universal naming scheme of oligonucleotides for Illumina, Affymetrix, and other microarrays

PubMed Central

Du, Pan; Kibbe, Warren A; Lin, Simon M

2007-01-01

Background Oligonucleotide probes that are sequence identical may have different identifiers between manufacturers and even between different versions of the same company's microarray; and sometimes the same identifier is reused and represents a completely different oligonucleotide, resulting in ambiguity and potentially mis-identification of the genes hybridizing to that probe. Results We have devised a unique, non-degenerate encoding scheme that can be used as a universal representation to identify an oligonucleotide across manufacturers. We have named the encoded representation 'nuID', for nucleotide universal identifier. Inspired by the fact that the raw sequence of the oligonucleotide is the true definition of identity for a probe, the encoding algorithm uniquely and non-degenerately transforms the sequence itself into a compact identifier (a lossless compression). In addition, we added a redundancy check (checksum) to validate the integrity of the identifier. These two steps, encoding plus checksum, result in an nuID, which is a unique, non-degenerate, permanent, robust and efficient representation of the probe sequence. For commercial applications that require the sequence identity to be confidential, we have an encryption schema for nuID. We demonstrate the utility of nuIDs for the annotation of Illumina microarrays, and we believe it has universal applicability as a source-independent naming convention for oligomers. Reviewers This article was reviewed by Itai Yanai, Rong Chen (nominated by Mark Gerstein), and Gregory Schuler (nominated by David Lipman). PMID:17540033

Surface plasmon resonance spectroscopy sensor and methods for using same

DOEpatents

Anderson, Brian Benjamin; Nave, Stanley Eugene

2002-01-01

A surface plasmon resonance ("SPR") probe with a detachable sensor head and system and methods for using the same in various applications is described. The SPR probe couples fiber optic cables directly to an SPR substrate that has a generally planar input surface and a generally curved reflecting surface, such as a substrate formed as a hemisphere. Forming the SPR probe in this manner allows the probe to be miniaturized and operate without the need for high precision, expensive and bulky collimating or focusing optics. Additionally, the curved reflecting surface of the substrate can be coated with one or multiple patches of sensing medium to allow the probe to detect for multiple analytes of interest or to provide multiple readings for comparison and higher precision. Specific applications for the probe are disclosed, including extremely high sensitive relative humidity and dewpoint detection for, e.g., moisture-sensitive environment such as volatile chemical reactions. The SPR probe disclosed operates with a large dynamic range and provides extremely high quality spectra despite being robust enough for field deployment and readily manufacturable.

A fast-response two-photon fluorescent probe for imaging endogenous H2O2 in living cells and tissues

NASA Astrophysics Data System (ADS)

Lu, Yanan; Shi, Xiaomin; Fan, Wenlong; Black, Cory A.; Lu, Zhengliang; Fan, Chunhua

2018-02-01

As a second messenger, hydrogen peroxide plays significant roles in numerous physiological and pathological processes and is related to various diseases including inflammatory disease, diabetes, neurodegenerative disorders, cardiovascular disease and Alzheimer's disease. Two-photon (TP) fluorescent probes reported for the detection of endogenous H2O2 are rare and most have drawbacks such as slow response and low sensitivity. In this report, we demonstrate a simple H2O2-specific TP fluorescent probe (TX-HP) containing a two-photon dye 6-hydroxy-2,3,4,4a-tetrahydro-1H-xanthen-1-one (TX) on the modulation of the ICT process. The probe exhibits a rapid fluorescent response to H2O2 in 9 min with both high sensitivity and selectivity. The probe can detect exogenous H2O2 in living cells. Furthermore, the probe is successfully utilized for imaging H2O2 in liver tissues.

Broadband sensitive pump-probe setup for ultrafast optical switching of photonic nanostructures and semiconductors.

PubMed

Euser, Tijmen G; Harding, Philip J; Vos, Willem L

2009-07-01

We describe an ultrafast time resolved pump-probe spectroscopy setup aimed at studying the switching of nanophotonic structures. Both femtosecond pump and probe pulses can be independently tuned over broad frequency range between 3850 and 21,050 cm(-1). A broad pump scan range allows a large optical penetration depth, while a broad probe scan range is crucial to study strongly photonic crystals. A new data acquisition method allows for sensitive pump-probe measurements, and corrects for fluctuations in probe intensity and pump stray light. We observe a tenfold improvement of the precision of the setup compared to laser fluctuations, allowing a measurement accuracy of better than DeltaR=0.07% in a 1 s measurement time. Demonstrations of the improved technique are presented for a bulk Si wafer, a three-dimensional Si inverse opal photonic bandgap crystal, and z-scan measurements of the two-photon absorption coefficient of Si, GaAs, and the three-photon absorption coefficient of GaP in the infrared wavelength range.

Spin-exchange relaxation-free magnetometer with nearly parallel pump and probe beams

DOE PAGES

Karaulanov, Todor; Savukov, Igor; Kim, Young Jin

2016-03-22

We constructed a spin-exchange relaxation-free (SERF) magnetometer with a small angle between the pump and probe beams facilitating a multi-channel design with a flat pancake cell. This configuration provides almost complete overlap of the beams in the cell, and prevents the pump beam from entering the probe detection channel. By coupling the lasers in multi-mode fibers, without an optical isolator or field modulation, we demonstrate a sensitivity of 10 fTmore » $$/\\sqrt{\\text{Hz}}$$ for frequencies between 10 Hz and 100 Hz. In addition to the experimental study of sensitivity, we present a theoretical analysis of SERF magnetometer response to magnetic fields for small-angle and parallel-beam configurations, and show that at optimal DC offset fields the magnetometer response is comparable to that in the orthogonal-beam configuration. Based on the analysis, we also derive fundamental and probe-limited sensitivities for the arbitrary non-orthogonal geometry. The expected practical and fundamental sensitivities are of the same order as those in the orthogonal geometry. As a result, we anticipate that our design will be useful for magnetoencephalography (MEG) and magnetocardiography (MCG) applications.« less

Pump-probe optical microscopy for imaging nonfluorescent chromophores.

PubMed

Wei, Lu; Min, Wei

2012-06-01

Many chromophores absorb light intensely but have undetectable fluorescence. Hence microscopy techniques other than fluorescence are highly desirable for imaging these chromophores inside live cells, tissues, and organisms. The recently developed pump-probe optical microscopy techniques provide fluorescence-free contrast mechanisms by employing several fundamental light-molecule interactions including excited state absorption, stimulated emission, ground state depletion, and the photothermal effect. By using the pump pulse to excite molecules and the subsequent probe pulse to interrogate the created transient states on a laser scanning microscope, pump-probe microscopy offers imaging capability with high sensitivity and specificity toward nonfluorescent chromophores. Single-molecule sensitivity has even been demonstrated. Here we review and summarize the underlying principles of this emerging class of molecular imaging techniques.

Development of LC-13C NMR

NASA Technical Reports Server (NTRS)

Dorn, H. C.; Wang, J. S.; Glass, T. E.

1986-01-01

This study involves the development of C-13 nuclear resonance as an on-line detector for liquid chromatography (LC-C-13 NMR) for the chemical characterization of aviation fuels. The initial focus of this study was the development of a high sensitivity flow C-13 NMR probe. Since C-13 NMR sensitivity is of paramount concern, considerable effort during the first year was directed at new NMR probe designs. In particular, various toroid coil designs were examined. In addition, corresponding shim coils for correcting the main magnetic field (B sub 0) homogeneity were examined. Based on these initial probe design studies, an LC-C-13 NMR probe was built and flow C-13 NMR data was obtained for a limited number of samples.

Detection of Cracks at Welds in Steel Tubing Using Flux Focusing Electromagnetic Probe

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min

1994-01-01

The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected by simply snaking an eddy current coil into the intake tube of the vessel. The drawback of the eddy current method has been the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at weldments [1]. The flaw detection mechanism of the flux focusing electromagnetic probe can help alleviate these difficulties and provide a unique capability for detecting longitudinal fatigue cracks in critical tube structures. The Flux Focusing Electromagnetic Flaw Detector, originally invented for the detection of fatigue and corrosion damage in aluminum plates [2-3], has been adapted for use in testing steel tubing for longitudinal fatigue cracks. The modified design allows for the probe to be placed axisymmetrically into the tubing, inducing eddy currents in the tube wall. The pickup coil of the probe is fixed slightly below the primary windings and is rotated 90 so that its axis is normal to the tube wall. The magnetic flux of the primary coil is focused through the use of ferromagnetic material so that in the absence of fatigue damage there will be no flux linkage with the pickup coil. The presence of a longitudinal fatigue crack will cause the eddy currents induced in the tube wall to flow around the flaw and directly under the pickup coil. The magnetic field associated with these currents will then link the pickup coil and an unambiguous increase in the output voltage of the probe will be measured. The use of the flux focusing electromagnetic probe is especially suited for the detection of flaws originating at or near tube welds. The probe is shown to discriminate against signals due solely to the weld joint so that flaw signals are not hidden in the background in these locations. Experimental and finite element modeling results are presented for the flaw detection capabilities of the probe in stainless steel tubes.

Usefulness of 1000-Hz probe tone in tympanometry according to age in Korean infants.

PubMed

Park, Mina; Han, Kyu-Hee; Jung, Hyunseo; Kim, Mee-Hee; Chang, Hyun-Kyung; Kim, Shin Hye; Park, Moo Kyun; Lee, Jun Ho

2015-01-01

Numerous studies have shown the superiority of a 1000-Hz frequency probe tone for evaluating the middle ear status of infants. However, most of these studies examined Caucasian populations. This study validated the 1000-Hz probe tone and evaluated the age at which it should be used in Korean infants. Data from 83 infants (43 males, 40 females; mean age 9.2±6.2 (range 1-30) months, 165 ears) were analyzed. Tympanograms were classified according to Baldwin's modification of the method of Marchant et al. and correlated with results based on combined diagnostic tests, including an endoscopic examination of the tympanic membrane, myringotomy findings, and the air and bone conduction auditory brainstem response (ABR) thresholds. Data were analyzed in five age groups, each covering a 3-month range. The traces were measured for both 226- and 1000-Hz probe tones. The sensitivity and specificity for the different age groups were also determined. For the 226-Hz probe tone, the tympanograms showed normal traces for most ears with otitis media effusions in infants younger than 12 months. By contrast, the tympanograms using the 1000-Hz probe tone showed abnormal traces in most of the infants with otitis media effusions in all age groups. In infants with no otitis media effusion, the tympanograms using both 226- and 1000-Hz probe tones were interpreted as normal in most cases in all age groups. In infants younger than 12 months, the sensitivity of the 226-Hz probe tone was very low (0-6.6%), whereas that of the 1000-Hz probe tone was very high (90-100%). In infants older than 13 months, however, the sensitivities of the 226- and 1000-Hz probe tones were 76.2% and 85.7%, respectively. Regarding specificity, the difference between the two probe tones was not significant for any age group. This study confirmed the superiority of the 1000-Hz probe tone for evaluating the middle ear in infants. We recommend using a 1000-Hz probe tone at least up to the age of 12 months for Korean infants. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A molecular rotor based ratiometric sensor for basic amino acids

NASA Astrophysics Data System (ADS)

Pettiwala, Aafrin M.; Singh, Prabhat K.

2018-01-01

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples.

Science of active galactic nuclei with the GTC and CanariCam

NASA Astrophysics Data System (ADS)

Levenson, Nancy A.; Packham, Christopher C.; Alonso-Herrero, Almudena; Aretxaga, Itziar; Colina, Luis; Díaz-Santos, Tanio; Elitzur, Moshe; Mason, Rachel E.; Perlman, Eric S.; Radomski, James T.; Roche, Patrick F.; Rodríguez Espinosa, José Miguel; Young, Stuart; Telesco, Charles M.

2008-07-01

CanariCam is the facility mid-infrared (MIR) instrument for the Gran Telescopio Canarias (GTC), a 10.4m telescope at the Observatorio del Roque de los Muchachos on La Palma. One of the science drivers for CanariCam is the study of active galactic nuclei (AGN). We will exploit the instrument's high sensitivity in imaging, spectroscopy, and polarimetry modes to answer fundamental questions of AGN and their host galaxies. Dust in the nucleus of an active galaxy reprocesses the intrinsic radiation of the central engine to emerge in the MIR. Current work demonstrates that the hot dust immediately associated with the AGN, which blocks direct views of the AGN from some lines of sight, is confined to small (parsec) scales. Thus, high spatial resolution is essential to probe the "torus" of unified AGN models separate from the host galaxy. CanariCam provides a 0.08" pixel scale for Nyquist sampling the diffraction-limited point spread function at 8μm, and narrow (0.2") spectroscopy slits (with R=120-1300). New observations with the GTC/CanariCam will provide key constraints on the physical conditions in the clumpy torus, and we will sensitively determine AGN obscuration as a function of nuclear activity. We will therefore address the fueling process and its relationship to the torus, the interaction with the host galaxy, and dust chemistry. These data will be essential preparation for the next generation of telescopes that will observe the distant universe directly to explore galaxy and black hole formation and evolution, and the GTC/CanariCam system uniquely provides multiple modes to probe AGN.

Probing the magnetic field dependence of the light hole transition in GaAs/AlGaAs quantum wells using optically pumped NMR

NASA Astrophysics Data System (ADS)

Willmering, Matthew M.; Sesti, Erika L.; Hayes, Sophia E.; Wood, Ryan M.; Bowers, Clifford R.; Thapa, Sunil K.; Stanton, Christopher J.; Reyes, Arneil P.; Kuhns, Philip; McGill, Stephen

2018-02-01

Optically pumped NMR (OPNMR) of the NMR-active Ga/7169 species has been shown to be a unique method to probe electronic energy bands in GaAs, with sensitivity to the light hole-to-conduction band transition. This transition is often obscured in other optical measurements such as magnetoabsorption. Using OPNMR, we exploit the hyperfine interaction between conduction band electrons (and their spin states) and nuclear spins, which are detected through phase-sensitive radio-frequency (NMR) spectroscopy. Measurements were made over a range of external magnetic fields (B0) in two different labs with separate experimental setups to obtain the magnetic field dependence of the light hole-to-conduction band transition energy. In addition, k .p theory was used to interpret the experimental results, mapping out this specific transition's magnetic field dependence in an AlGaAs/GaAs quantum well. The combination of theory and experiment point to a mixing of valence bands at a field of approximately B0=4.7 T, swapping the dominant character of the absorption transition and, thus, explaining the magnetic field dependence. Lastly, the experimental dependence of the light hole-to-conduction band transition energy on B0 is found to be less steep compared to the calculated trend, indicating that inclusion of additional effects may be necessary to accurately model the spin-split band structure. The additional insight gained by Ga/7169 OPNMR about the light hole states will facilitate future testing of more complex band structure models.

Characterizing the performance of an affordable, multichannel conductivity probe for density measurements in stratified flows

NASA Astrophysics Data System (ADS)

Subramanian, Balaji; Carminati, Marco; Luzzatto-Fegiz, Paolo

2017-11-01

In stratified flows, conductivity (combined with temperature) is often used to measure density. The conductivity probes typically used can resolve very fine spatial scales, but on the downside they are fragile, expensive, sensitive to environmental noise and have only single channel capability. Recently a low-cost, robust, arduino-based probe called Conduino was developed, which can be valuable in a wide range of applications where resolving extremely small spatial scales is not needed. This probe uses micro-USB connectors as actual conductivity sensors with a custom designed electronic board for simultaneous acquisition from multiple probes, with conductivity resolution comparable to commercially available PME conductivity probe. A detailed assessment of performance of this Conduino probe is described here. To establish time response and sensitivity as a function of electrode geometry, we build a variety of shapes for different kinds of applications, with tip spacing ranging from 0.5-2.5 mm, and with electrode length ranging from 2.3-6 mm. We set up a two-layer density profile and traverse it rapidly, yielding a time response comparable to PME. The Conduino's multi-channel capability is used to operate probe arrays, which helps to construct density fields in stratified flows.

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

Monitoring Membrane Hydration with 2-(Dimethylamino)-6-Acylnaphtalenes Fluorescent Probes.

PubMed

Bagatolli, Luis A

2015-01-01

A family of polarity sensitive fluorescent probes (2-(dimethylamino)-6-acylnaphtalenes, i.e. LAURDAN, PRODAN, ACDAN) was introduced by Gregorio Weber in 1979, with the aim to monitor solvent relaxation phenomena on protein matrices. In the following years, however, PRODAN and particularly LAURDAN, were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane/water interface. For instance, when glycerophospholipid containing membranes undertake a solid ordered (gel) to liquid disordered phase transition the fluorescence emission maximum of these probes shift ~ 50 nm with a significant change in their fluorescence lifetime. Furthermore, the fluorescence parameters of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting comparative studies. This chapter presents a short historical overview about these fluorescent reporters, discusses on different models proposed to explain their sensitivity to membrane hydration, and includes relevant examples from experiments performed in artificial and biological membranes.

Signal-off Electrochemiluminescence Biosensor Based on Phi29 DNA Polymerase Mediated Strand Displacement Amplification for MicroRNA Detection.

PubMed

Chen, Anyi; Gui, Guo-Feng; Zhuo, Ying; Chai, Ya-Qin; Xiang, Yun; Yuan, Ruo

2015-06-16

A target induced cycling strand displacement amplification (SDA) mediated by phi29 DNA polymerase (phi29) was first investigated and applied in a signal-off electrochemiluminescence (ECL) biosensor for microRNA (miRNA) detection. Herein, the target miRNA triggered the phi29-mediated SDA which could produce amounts of single-stranded DNA (assistant probe) with accurate and comprehensive nucleotide sequence. Then, the assistant probe hybridized with the capture probe and the ferrocene-labeled probe (Fc-probe) to form a ternary "Y" structure for ECL signal quenching by ferrocene. Therefore, the ECL intensity would decrease with increasing concentration of the target miRNA, and the sensitivity of biosensor would be promoted on account of the efficient signal amplification of the target induced cycling reaction. Besides, a self-enhanced Ru(II) ECL system was designed to obtain a stable and strong initial signal to further improve the sensitivity. The ECL assay for miRNA-21 detection is developed with excellent sensitivity of a concentration variation from 10 aM to 1.0 pM and limit of detection down to 3.3 aM.

Physical key-protected one-time pad

PubMed Central

Horstmeyer, Roarke; Judkewitz, Benjamin; Vellekoop, Ivo M.; Assawaworrarit, Sid; Yang, Changhuei

2013-01-01

We describe an encrypted communication principle that forms a secure link between two parties without electronically saving either of their keys. Instead, random cryptographic bits are kept safe within the unique mesoscopic randomness of two volumetric scattering materials. We demonstrate how a shared set of patterned optical probes can generate 10 gigabits of statistically verified randomness between a pair of unique 2 mm3 scattering objects. This shared randomness is used to facilitate information-theoretically secure communication following a modified one-time pad protocol. Benefits of volumetric physical storage over electronic memory include the inability to probe, duplicate or selectively reset any bits without fundamentally altering the entire key space. Our ability to securely couple the randomness contained within two unique physical objects can extend to strengthen hardware required by a variety of cryptographic protocols, which is currently a critically weak link in the security pipeline of our increasingly mobile communication culture. PMID:24345925

Subpiconewton intermolecular force microscopy.

PubMed

Tokunaga, M; Aoki, T; Hiroshima, M; Kitamura, K; Yanagida, T

1997-02-24

We refined scanning probe force microscopy to improve the sensitivity of force detection and control of probe position. Force sensitivity was increased by incorporating a cantilever with very low stiffness, 0.1 pN/ nm, which is over 1000-fold more flexible than is typically used in conventional atomic force microscopy. Thermal bending motions of the cantilever were reduced to less than 1 nm by exerting feed-back positioning with laser radiation pressure. The system was tested by measuring electrostatic repulsive forces or hydrophobic attractive forces in aqueous solutions. Subpiconewton intermolecular forces were resolved at controlled gaps in the nanometer range between the probe and a material surface. These levels of force and position sensitivity meet the requirements needed for future investigations of intermolecular forces between biological macromolecules such as proteins, lipids and DNA.

Highly selective and sensitive detection of Cu2+ with lysine enhancing bovine serum albumin modified-carbon dots fluorescent probe.

PubMed

Liu, Jia-Ming; Lin, Li-ping; Wang, Xin-Xing; Lin, Shao-Qin; Cai, Wen-Lian; Zhang, Li-Hong; Zheng, Zhi-Yong

2012-06-07

Based on the ability of lysine (Lys) to enhance the fluorescence intensity of bovine serum albumin modified-carbon dots (CDs-BSA) to decrease surface defects and quench fluorescence of the CDs-BSA-Lys system in the presence of Cu(2+) under conditions of phosphate buffer (PBS, pH = 5.0) at 45 °C for 10 min, a sensitive Lys enhancing CDs-BSA fluorescent probe was designed. The environment-friendly, simple, rapid, selective and sensitive fluorescent probe has been utilized to detect Cu(2+) in hair and tap water samples and it achieved consistent results with those obtained by inductively coupled plasma mass spectroscopy (ICP-MS). The mechanism of the proposed assay for the detection of Cu(2+) is discussed.

High quality-factor quartz tuning fork glass probe used in tapping mode atomic force microscopy for surface profile measurement

NASA Astrophysics Data System (ADS)

Chen, Yuan-Liu; Xu, Yanhao; Shimizu, Yuki; Matsukuma, Hiraku; Gao, Wei

2018-06-01

This paper presents a high quality-factor (Q-factor) quartz tuning fork (QTF) with a glass probe attached, used in frequency modulation tapping mode atomic force microscopy (AFM) for the surface profile metrology of micro and nanostructures. Unlike conventionally used QTFs, which have tungsten or platinum probes for tapping mode AFM, and suffer from a low Q-factor influenced by the relatively large mass of the probe, the glass probe, which has a lower density, increases the Q-factor of the QTF probe unit allowing it to obtain better measurement sensitivity. In addition, the process of attaching the probe to the QTF with epoxy resin, which is necessary for tapping mode AFM, is also optimized to further improve the Q-factor of the QTF glass probe. The Q-factor of the optimized QTF glass probe unit is demonstrated to be very close to that of a bare QTF without a probe attached. To verify the effectiveness and the advantages of the optimized QTF glass probe unit, the probe unit is integrated into a home-built tapping mode AFM for conducting surface profile measurements of micro and nanostructures. A blazed grating with fine tool marks of 100 nm, a microprism sheet with a vertical amplitude of 25 µm and a Fresnel lens with a steep slope of 90 degrees are used as measurement specimens. From the measurement results, it is demonstrated that the optimized QTF glass probe unit can achieve higher sensitivity as well as better stability than conventional probes in the measurement of micro and nanostructures.

Developments in Scanning Hall Probe Microscopy

NASA Astrophysics Data System (ADS)

Chouinard, Taras; Chu, Ricky; David, Nigel; Broun, David

2009-05-01

Low temperature scanning Hall probe microscopy is a sensitive means of imaging magnetic structures with high spatial resolution and magnetic flux sensitivity approaching that of a Superconducting Quantum Interference Device. We have developed a scanning Hall probe microscope with novel features, including highly reliable coarse positioning, in situ optimization of sensor-sample alignment and capacitive transducers for linear, long range positioning measurement. This has been motivated by the need to reposition accurately above fabricated nanostructures such as small superconducting rings. Details of the design and performance will be presented as well as recent progress towards time-resolved measurements with sub nanosecond resolution.

A sub-nanomolar real-time nitric oxide probe: in vivo nitric oxide release in heart.

PubMed

Mantione, Kirk J; Stefano, George B

2004-04-01

Amperometric nitric oxide probes are critical in evaluating real-time nitric oxide levels. This valuable tool enables one to measure spontaneous baseline levels of nitric oxide as well as 'puffs' of the gaseous signal molecule that may last for only seconds to minutes. However, in the past, many probes suffered from a lack of sensitivity, durability and reliability, causing investigators to design numerous controls to support their data. Our laboratory evaluated the new ISO-NOPF100 NO probe manufactured by World Precision Instruments of Sarasota, Florida. An invertebrate in vivo heart preparation was used, which presents a high degree of difficuly in obtaining nitric oxide measurements due to space limitations, resulting in physical contact of the probe with tissues. Additionally, we used in vitro invertebrate ganglionic preparations as a comparison since this tissue releases spontaneous and low levels of NO. Calibration of the new probe demonstrated high linearity and sensitivity. The detection limit for this new probe was determined to be approximately two times lower than probes previously used in our laboratory. Basal nitric oxide fluctuations in Mytilus edulis heart and excised ganglia were able to be resolved in the sub-nanomolar range. The ISO-NOPF100 NO probe represents a significant advancement for measuring nitric oxide in real-time.

Accreting Double White Dwarf Binaries: Implications for LISA

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

Kremer, Kyle; Breivik, Katelyn; Larson, Shane L.

We explore the long-term evolution of mass-transferring white dwarf (WD) binaries undergoing both direct-impact and disk accretion and explore implications of such systems to gravitational-wave (GW) astronomy. We cover a broad range of initial component masses and show that these systems, the majority of which lie within the Laser Interferometer Space Antenna ( LISA ) sensitivity range, exhibit prominent negative orbital frequency evolution (chirp) for a significant fraction of their lifetimes. Using a galactic population synthesis, we predict ∼2700 of these systems will be observable with a negative chirp of 0.1 yr{sup −2} by a space-based GW detector like LISAmore » . We also show that detections of mass-transferring double WD systems by LISA may provide astronomers with unique ways of probing the physics governing close compact object binaries.« less

Cavity optomechanical spring sensing of single molecules

NASA Astrophysics Data System (ADS)

Yu, Wenyan; Jiang, Wei C.; Lin, Qiang; Lu, Tao

2016-07-01

Label-free bio-sensing is a critical functionality underlying a variety of health- and security-related applications. Micro-/nano-photonic devices are well suited for this purpose and have emerged as promising platforms in recent years. Here we propose and demonstrate an approach that utilizes the optical spring effect in a high-Q coherent optomechanical oscillator to dramatically enhance the sensing resolution by orders of magnitude compared with conventional approaches, allowing us to detect single bovine serum albumin proteins with a molecular weight of 66 kDa at a signal-to-noise ratio of 16.8. The unique optical spring sensing approach opens up a distinctive avenue that not only enables biomolecule sensing and recognition at individual level, but is also of great promise for broad physical sensing applications that rely on sensitive detection of optical cavity resonance shift to probe external physical parameters.

Recent Progress in DIB Research: Survey of PAHS and DIBS

NASA Technical Reports Server (NTRS)

Salama, Farid; Galazutdinov, G.; Krelowski, J.; Biennier, L.; Beletsky, Y.; Song, I.

2013-01-01

The spectra of several neutral and ionized PAHs isolated in the gas phase at low temperature have been measured in the laboratory under experimental conditions that mimic interstellar conditions and are compared with an extensive set of astronomical spectra of reddened, early type stars [1, 2]. The comparisons of astronomical and laboratory data provide upper limits for the abundances of specific neutral PAH molecules and ions along specific lines-of-sight. Something that is not attainable from infrared observations alone. We present the characteristics of the laboratory facility (COSmIC) that was developed for this study and discuss the findings resulting from the comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations. COSmIC combines a supersonic free jet expansion with discharge plasma and high-sensitivity cavity ringdown spectroscopy and provides experimental conditions that closely mimic the interstellar conditions. The column densities of the individual neutral PAH molecules and ions probed in these surveys are derived from the comparison of these unique laboratory data with high resolution, high S/N ratio astronomical observations. The comparisons of astronomical and laboratory data lead to clear and unambiguous conclusions regarding the expected abundances for PAHs of various sizes and charge states in the interstellar environments probed in the surveys. Band profile comparisons between laboratory and astronomical spectra lead to information regarding the molecular structures and characteristics associated with the DIB carriers in the corresponding lines-of-sight. These quantitative surveys of neutral and ionized PAHs in the optical range open the way for unambiguous quantitative searches of PAHs and complex organics in a variety of interstellar and circumstellar environments.

Automated design of genomic Southern blot probes

PubMed Central

2010-01-01

Background Sothern blotting is a DNA analysis technique that has found widespread application in molecular biology. It has been used for gene discovery and mapping and has diagnostic and forensic applications, including mutation detection in patient samples and DNA fingerprinting in criminal investigations. Southern blotting has been employed as the definitive method for detecting transgene integration, and successful homologous recombination in gene targeting experiments. The technique employs a labeled DNA probe to detect a specific DNA sequence in a complex DNA sample that has been separated by restriction-digest and gel electrophoresis. Critically for the technique to succeed the probe must be unique to the target locus so as not to cross-hybridize to other endogenous DNA within the sample. Investigators routinely employ a manual approach to probe design. A genome browser is used to extract DNA sequence from the locus of interest, which is searched against the target genome using a BLAST-like tool. Ideally a single perfect match is obtained to the target, with little cross-reactivity caused by homologous DNA sequence present in the genome and/or repetitive and low-complexity elements in the candidate probe. This is a labor intensive process often requiring several attempts to find a suitable probe for laboratory testing. Results We have written an informatic pipeline to automatically design genomic Sothern blot probes that specifically attempts to optimize the resultant probe, employing a brute-force strategy of generating many candidate probes of acceptable length in the user-specified design window, searching all against the target genome, then scoring and ranking the candidates by uniqueness and repetitive DNA element content. Using these in silico measures we can automatically design probes that we predict to perform as well, or better, than our previous manual designs, while considerably reducing design time. We went on to experimentally validate a number of these automated designs by Southern blotting. The majority of probes we tested performed well confirming our in silico prediction methodology and the general usefulness of the software for automated genomic Southern probe design. Conclusions Software and supplementary information are freely available at: http://www.genes2cognition.org/software/southern_blot PMID:20113467

The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe

PubMed Central

Cheng, Bingbing; Bandi, Venugopal; Yu, Shuai; D’Souza, Francis; Nguyen, Kytai T.; Hong, Yi; Tang, Liping; Yuan, Baohong

2017-01-01

Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)2, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF) imaging. The fluorescence of the ADP(CA)2 is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA)2 can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA)2 inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold) was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree) of ADP(CA)2-based temperature probes was found in temperature sensing. PMID:28208666

Recognition unit-free and self-cleaning photoelectrochemical sensing platform on TiO2 nanotube photonic crystals for sensitive and selective detection of dopamine release from mouse brain.

PubMed

Xin, Yanmei; Li, Zhenzhen; Wu, Wenlong; Fu, Baihe; Wu, Hongjun; Zhang, Zhonghai

2017-01-15

For implementing sensitive and selective detection of biological molecules, the biosensors are been designed more and more complicated. The exploration of detection platform in a simple way without loss their sensitivity and selectivity is always a big challenge. Herein, a prototype of recognition biomolecule unit-free photoelectrochemical (PEC) sensing platform with self-cleaning activity is proposed with TiO 2 nanotube photonic crystal (TiO 2 NTPCs) materials as photoelectrode, and dopamine (DA) molecule as both sensitizer and target analyte. The unique adsorption between DA and TiO 2 NTPCs induces the formation of charge transfer complex, which not only expends the optical absorption of TiO 2 into visible light region, thus significantly boosts the PEC performance under illumination of visible light, but also implements the selective detection of DA on TiO 2 photoelectrode. This simple but efficient PEC analysis platform presents a low detection limit of 0.15nm for detection of DA, which allows to realize the sensitive and selective determination of DA release from the mouse brain for its practical application after coupled with a microdialysis probe. The DA functionalized TiO 2 NTPCs PEC sensing platform opens up a new PEC detection model, without using extra-biomolecule auxiliary, just with target molecule naturally adsorbed on the electrode for sensitive and selective detection, and paves a new avenue for biosensors design with minimalism idea. Copyright © 2016 Elsevier B.V. All rights reserved.

pH-Dependent Optical Properties of Synthetic Fluorescent Imidazoles

PubMed Central

Berezin, Mikhail Y.; Kao, Jeff; Achilefu, Samuel

2010-01-01

An imidazole moiety is often found as an integral part of fluorophores in a variety of fluorescent proteins and many such proteins possess pH dependent light emission. In contrast, synthetic fluorescent compounds with incorporated imidazoles are rare and have not been studied as pH probes. In this report, the richness of imidazole optical properties, including pH sensitivity, was demonstrated via a novel imidazole-based fluorophore 1H-imidazol-5-yl-vinyl-benz[e]indolium. Three species corresponding to protonated, neutral and deprotonated imidazoles were identified in the broad range of pH 1-12. The absorption and emission bands of each species were assigned by comparative spectral analysis with synthesized mono- and di-N-methylated fluorescent imidazole analogues. pKa analysis in the ground and the excited states showed photoacidic properties of the fluorescent imidazoles due to the excited state proton transfer (ESPT). This effect was negligible for substituted imidazoles. The assessment of a pH sensitive center in the imidazole ring revealed the switching of the pH sensitive centers from 1-N in the ground state to 3-N in the excited state. The effect was attributed to the unique kind of the excited state charge transfer (ESCT) resulting in a positive charge swapping between two nitrogens. PMID:19212987

Nanometre-scale thermometry in a living cell

NASA Astrophysics Data System (ADS)

Kucsko, G.; Maurer, P. C.; Yao, N. Y.; Kubo, M.; Noh, H. J.; Lo, P. K.; Park, H.; Lukin, M. D.

2013-08-01

Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical and chemical research. Possibilities range from the temperature-induced control of gene expression and tumour metabolism to the cell-selective treatment of disease and the study of heat dissipation in integrated circuits. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the subcellular level. Here we demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen-vacancy colour centres in diamond. Our technique makes it possible to detect temperature variations as small as 1.8 mK (a sensitivity of 9 mK Hz-1/2) in an ultrapure bulk diamond sample. Using nitrogen-vacancy centres in diamond nanocrystals (nanodiamonds), we directly measure the local thermal environment on length scales as short as 200 nanometres. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the subcellular level, enabling unique potential applications in life sciences.

Ultra-sensitive probe of spectral line structure and detection of isotopic oxygen

NASA Astrophysics Data System (ADS)

Garner, Richard M.; Dharamsi, A. N.; Khan, M. Amir

2018-01-01

We discuss a new method of investigating and obtaining quantitative behavior of higher harmonic (> 2f) wavelength modulation spectroscopy (WMS) based on the signal structure. It is shown that the spectral structure of higher harmonic WMS signals, quantified by the number of zero crossings and turnings points, can have increased sensitivity to ambient conditions or line-broadening effects from changes in temperature, pressure, or optical depth. The structure of WMS signals, characterized by combinations of signal magnitude and spectral locations of turning points and zero crossings, provides a unique scale that quantifies lineshape parameters and, thus, useful in optimization of measurements obtained from multi-harmonic WMS signals. We demonstrate this by detecting weaker rotational-vibrational transitions of isotopic atmospheric oxygen (16O18O) in the near-infrared region where higher harmonic WMS signals are more sensitive contrary to their signal-to-noise ratio considerations. The proposed approach based on spectral structure provides the ability to investigate and quantify signals not only at linecenter but also in the wing region of the absorption profile. This formulation is particularly useful in tunable diode laser spectroscopy and ultra-precision laser-based sensors where absorption signal profile carries information of quantities of interest, e.g., concentration, velocity, or gas collision dynamics, etc.

Protein recognition by a pattern-generating fluorescent molecular probe.

PubMed

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

2017-12-01

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

Protein recognition by a pattern-generating fluorescent molecular probe

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Impact of mandibular third molar extraction in the second molar periodontal status: A prospective study.

PubMed

Stella, Paulo Eduardo Melo; Falci, Saulo Gabriel Moreira; Oliveira de Medeiros, Lorrayne Estéfane; Douglas-de-Oliveira, Dhelfeson Willya; Gonçalves, Patricia Furtado; Flecha, Olga Dumont; Dos Santos, Cássio Roberto Rocha

2017-01-01

The aim of the present study was to assess the periodontal condition and sensitivity of second mandibular molars after the extraction of the adjacent third molar, while also assessing the quality of life of the patients. Twenty-three healthy patients were assessed in terms of probing depth, gingival height, gingival thickness, dental sensitivity, plaque index and bleeding on probing (adjacent second mandibular molar), before the surgical procedure, as well as 60 and 180 days after the surgery. The following data were also recorded and measured: the position and size of the impacted teeth; the size of the alveoli after surgery and the quality of life of the patient. Significant differences were found for probing depth and gingival height before and after 180 days. The plaque index increased significantly after surgery ( P = 0.004), as did bleeding on probing. No significant difference was found for the quality of life. The size of the third molar extracted was correlated with bleeding on probing 180 days after the surgery. An improvement was noted in the periodontal condition of the second mandibular molars after the extraction, based on the assessments of probing depth and gingival height. The position of the third molar affected the periodontal condition of the second mandibular molar. No alterations were recorded for dental sensitivity or the quality of life after the extraction.

Impact of mandibular third molar extraction in the second molar periodontal status: A prospective study

PubMed Central

Stella, Paulo Eduardo Melo; Falci, Saulo Gabriel Moreira; Oliveira de Medeiros, Lorrayne Estéfane; Douglas-de-Oliveira, Dhelfeson Willya; Gonçalves, Patricia Furtado; Flecha, Olga Dumont; Dos Santos, Cássio Roberto Rocha

2017-01-01

Aim: The aim of the present study was to assess the periodontal condition and sensitivity of second mandibular molars after the extraction of the adjacent third molar, while also assessing the quality of life of the patients. Materials and Methods: Twenty-three healthy patients were assessed in terms of probing depth, gingival height, gingival thickness, dental sensitivity, plaque index and bleeding on probing (adjacent second mandibular molar), before the surgical procedure, as well as 60 and 180 days after the surgery. The following data were also recorded and measured: the position and size of the impacted teeth; the size of the alveoli after surgery and the quality of life of the patient. Results: Significant differences were found for probing depth and gingival height before and after 180 days. The plaque index increased significantly after surgery (P = 0.004), as did bleeding on probing. No significant difference was found for the quality of life. The size of the third molar extracted was correlated with bleeding on probing 180 days after the surgery. Conclusion: An improvement was noted in the periodontal condition of the second mandibular molars after the extraction, based on the assessments of probing depth and gingival height. The position of the third molar affected the periodontal condition of the second mandibular molar. No alterations were recorded for dental sensitivity or the quality of life after the extraction. PMID:29456302

Sensitive and Selective Ratiometric Fluorescence Probes for Detection of Intracellular Endogenous Monoamine Oxidase A.

PubMed

Wu, Xiaofeng; Li, Lihong; Shi, Wen; Gong, Qiuyu; Li, Xiaohua; Ma, Huimin

2016-01-19

Monoamine oxidase A (MAO-A) is known to widely exist in most cell lines in the body, and its dysfunction (unusually high or low levels of MAO-A) is thought to be responsible for several psychiatric and neurological disorders. Thus, a sensitive and selective method for evaluating the relative MAO-A levels in different live cells is urgently needed to better understand the function of MAO-A, but to our knowledge such a method is still lacking. Herein, we rationally design two new ratiometric fluorescence probes (1 and 2) that can sensitively and selectively detect MAO-A. The probes are constructed by incorporating a recognition group of propylamine into the fluorescent skeleton of 1,8-naphthalimide, and the detection mechanism is based on amine oxidation and β-elimination to release the fluorophore (4-hydroxy-N-butyl-1,8-naphthalimide), which is verified by HPLC analysis. Reaction of the probes with MAO-A produces a remarkable fluorescence change from blue to green, and the ratio of fluorescence intensity at 550 and 454 nm is directly proportional to the concentration of MAO-A in the ranges of 0.5-1.5 and 0.5-2.5 μg/mL with detection limits of 1.1 and 10 ng/mL (k = 3) for probes 1 and 2, respectively. Surprisingly, these probes show strong fluorescence responses to MAO-A but almost none to MAO-B (one of two isoforms of MAO), indicating superior ability to distinguish MAO-A from MAO-B. The high specificity of the probes for MAO-A over MAO-B is further supported by different inhibitor experiments. Moreover, probe 1 displays higher sensitivity than probe 2 and is thus investigated to image the relative MAO-A levels in different live cells, such as HeLa and NIH-3T3 cells. It is found that the concentration of endogenous MAO-A in HeLa cells is approximately 1.8 times higher than that in NIH-3T3 cells, which is validated by the result from an ELISA kit. Additionally, the proposed probes may find more uses in the specific detection of MAO-A between the two isoforms of MAO, thereby promoting our understanding of the behavior and function of MAO-A in living biosystems.

Ultrasensitive FRET-based DNA sensor using PNA/DNA hybridization.

PubMed

Yang, Lan-Hee; Ahn, Dong June; Koo, Eunhae

2016-12-01

In the diagnosis of genetic diseases, rapid and highly sensitive DNA detection is crucial. Therefore, many strategies for detecting target DNA have been developed, including electrical, optical, and mechanical methods. Herein, a highly sensitive FRET based sensor was developed by using PNA (Peptide Nucleic Acid) probe and QD, in which red color QDs are hybridized with capture probes, reporter probes and target DNAs by EDC-NHS coupling. The hybridized probe with target DNA gives off fluorescent signal due to the energy transfer from QD to Cy5 dye in the reporter probe. Compared to the conventional DNA sensor using DNA probes, the DNA sensor using PNA probes shows higher FRET factor and efficiency due to the higher reactivity between PNA and target DNA. In addition, to elicit the effect of the distance between the donor and the acceptor, we have investigated two types of the reporter probes having Cy5 dyes attached at the different positions of the reporter probes. Results show that the shorter the distance between QDs and Cy5s, the stronger the signal intensity. Furthermore, based on the fluorescence microscopy images using microcapillary chips, the FRET signal is enhanced to be up to 276% times stronger than the signal obtained using the cuvette by the fluorescence spectrometer. These results suggest that the PNA probe system conjugated with QDs can be used as ultrasensitive DNA nanosensors. Copyright © 2016. Published by Elsevier B.V.

Experimental Overview of Direct Photon Results in Heavy Ion Collisions

NASA Astrophysics Data System (ADS)

Novitzky, Norbert

2016-07-01

Direct photons are color blind probes and thus they provide unique opportunities to study the colored medium created in heavy ion collisions. There are many different sources of direct photons each probing different physics processes as the system evolves. In basic 2 → 2 processes the prompt photons from primary hard scatterings offer the most precise measurements of the outgoing parton energy in the opposite direction. In heavy ion collisions the created medium emits photons as thermal radiation, whose rate and anisotropies provide a unique prospective on the properties and evolution of the system. Recent results on direct photons from the LHC and RHIC experiments are briefly summarized in this paper.

Quaternary ammonium promoted ultra selective and sensitive fluorescence detection of fluoride ion in water and living cells.

PubMed

Li, Long; Ji, Yuzhuo; Tang, Xinjing

2014-10-21

Highly selective and sensitive fluorescent probes with a quaternary ammonium moiety have been rationally designed and developed for fast and sensitive fluorescence detection of fluoride ion (F(-) from NaF, not TBAF) in aqueous solution and living cells. With the sequestration effect of quaternary ammonium, the detection time was less than 2 min and the detection limit of fluoride ion was as low as 0.57 ppm that is among the lowest detection limits in aqueous solutions of many fluoride fluorescence probes in the literature.

Unique NWA 11119/11558, NWA 7325 (and Pairs) and Almahata Sitta Individuals MS-MU 011/035: New Light on Very Early Parent Body Differentiation

NASA Astrophysics Data System (ADS)

Hoffmann, V. H.; Mikouchi, T.; Hochleitner, R.; Kaliwoda, M.; Wimmer, K.

2018-05-01

The preliminary results would support our conclusion that these unique meteorites may probe the crust/upper mantle of a yet unknown planetary body which existed only in a very early period of time of our planetary system.

Probing lipid membrane electrostatics

NASA Astrophysics Data System (ADS)

Yang, Yi

The electrostatic properties of lipid bilayer membranes play a significant role in many biological processes. Atomic force microscopy (AFM) is highly sensitive to membrane surface potential in electrolyte solutions. With fully characterized probe tips, AFM can perform quantitative electrostatic analysis of lipid membranes. Electrostatic interactions between Silicon nitride probes and supported zwitterionic dioleoylphosphatidylcholine (DOPC) bilayer with a variable fraction of anionic dioleoylphosphatidylserine (DOPS) were measured by AFM. Classical Gouy-Chapman theory was used to model the membrane electrostatics. The nonlinear Poisson-Boltzmann equation was numerically solved with finite element method to provide the potential distribution around the AFM tips. Theoretical tip-sample electrostatic interactions were calculated with the surface integral of both Maxwell and osmotic stress tensors on tip surface. The measured forces were interpreted with theoretical forces and the resulting surface charge densities of the membrane surfaces were in quantitative agreement with the Gouy-Chapman-Stern model of membrane charge regulation. It was demonstrated that the AFM can quantitatively detect membrane surface potential at a separation of several screening lengths, and that the AFM probe only perturbs the membrane surface potential by <2%. One important application of this technique is to estimate the dipole density of lipid membrane. Electrostatic analysis of DOPC lipid bilayers with the AFM reveals a repulsive force between the negatively charged probe tips and the zwitterionic lipid bilayers. This unexpected interaction has been analyzed quantitatively to reveal that the repulsion is due to a weak external field created by the internai membrane dipole moment. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported DOPC membranes. This new ability to quantitatively measure the membrane dipole density in a noninvasive manner will be useful in identifying the biological effects of the dipole potential. Finally, heterogeneous model membranes were studied with fluid electric force microscopy (FEFM). Electrostatic mapping was demonstrated with 50 nm resolution. The capabilities of quantitative electrostatic measurement and lateral charge density mapping make AFM a unique and powerful probe of membrane electrostatics.

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

PubMed Central

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

2012-01-01

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

pH Meter probe assembly

DOEpatents

Hale, C.J.

1983-11-15

An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe. 1 fig.

pH Meter probe assembly

DOEpatents

Hale, Charles J.

1983-01-01

An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe.

Real-time monitoring of drug-induced changes in the stomach acidity of living rats using improved pH-sensitive nitroxides and low-field EPR techniques

NASA Astrophysics Data System (ADS)

Potapenko, Dmitrii I.; Foster, Margaret A.; Lurie, David J.; Kirilyuk, Igor A.; Hutchison, James M. S.; Grigor'ev, Igor A.; Bagryanskaya, Elena G.; Khramtsov, Valery V.

2006-09-01

New improved pH-sensitive nitroxides were applied for in vivo studies. An increased stability of the probes towards reduction was achieved by the introduction of the bulky ethyl groups in the vicinity of the paramagnetic N sbnd O fragment. In addition, the range of pH sensitivity of the approach was extended by the synthesis of probes with two ionizable groups, and, therefore, with two p Ka values. Stability towards reduction and spectral characteristics of the three new probes were determined in vitro using 290 MHz radiofrequency (RF)- and X-band electron paramagnetic resonance (EPR), longitudinally detected EPR (LODEPR), and field-cycled dynamic nuclear polarization (FC-DNP) techniques. The newly synthesized probe, 4-[bis(2-hydroxyethyl)amino]-2-pyridine-4-yl-2,5,5-triethyl-2,5-dihydro-1 H-imidazol-oxyl, was found to be the most appropriate for the application in the stomach due to both higher stability and convenient pH sensitivity range from pH 1.8 to 6. LODEPR, FC-DNP and proton-electron double resonance imaging (PEDRI) techniques were used to detect the nitroxide localization and acidity in the rat stomach. Improved probe characteristics allowed us to follow in vivo the drug-induced perturbation in the stomach acidity and its normalization afterwards during 1 h or longer period of time. The results show the applicability of the techniques for monitoring drug pharmacology and disease in the living animals.

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

Chen, Qing; Gerhardt, Michael R.; Aziz, Michael J.

We measure the polarization characteristics of a quinone-bromide redox flow battery with interdigitated flow fields, using electrochemical impedance spectroscopy and voltammetry of a full cell and of a half cell against a reference electrode. We find linear polarization behavior at 50% state of charge all the way to the short-circuit current density of 2.5 A/cm 2. We uniquely identify the polarization area-specific resistance (ASR) of each electrode, the membrane ASR to ionic current, and the electronic contact ASR. We use voltage probes to deduce the electronic current density through each sheet of carbon paper in the quinone-bearing electrode. By alsomore » interpreting the results using the Newman 1-D porous electrode model, we deduce the volumetric exchange current density of the porous electrode. We uniquely evaluate the power dissipation and identify a correspondence to the contributions to the electrode ASR from the faradaic, electronic, and ionic transport processes. We find that, within the electrode, more power is dissipated in the faradaic process than in the electronic and ionic conduction processes combined, despite the observed linear polarization behavior. We examine the sensitivity of the ASR to the values of the model parameters. The greatest performance improvement is anticipated from increasing the volumetric exchange current density.« less

A new hydroxynaphthyl benzothiazole derived fluorescent probe for highly selective and sensitive Cu2 + detection

NASA Astrophysics Data System (ADS)

Tang, Lijun; He, Ping; Zhong, Keli; Hou, Shuhua; Bian, Yanjiang

2016-12-01

A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu2 + in DMSO/H2O (7/3, v/v, Tris-HCl 10 mM, pH = 7.4) solution based on Cu2 + catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205 min- 1. Moreover, application of BTNP to Cu2 + detection in living cells and real water samples was also explored.

Sensitive and rapid detection of endogenous hydrogen sulfide distributing in different mouse viscera via a two-photon fluorescent probe.

PubMed

Chen, Qian; Yang, Jinfeng; Li, Yinhui; Zheng, Jing; Yang, Ronghua

2015-10-08

Development of efficient methods for detection of endogenous H2S in living cells and tissues is of considerable significance for better understanding the biological and pathological functions of H2S. Two-photon (TP) fluorescent probes are favorable as powerful molecular tools for studying physiological process due to its non-invasiveness, high spatiotemporal resolution and deep-tissues imaging. Up to date, several TP probes for intracellular H2S imaging have been designed, but real-time imaging of endogenous H2S-related biological processes in tissues is hampered due to low sensitivity, long response time and interference from other biothiols. To address this issue, we herein report a novel two-photon fluorescent probe (TPP-H2S) for highly sensitive and fast monitoring and imaging H2S levels in living cells and tissues. In the presence of H2S, it exhibits obviously improved sensitivity (LOD: 0.12 μM) and fast response time (about 2 min) compared with the reported two-photon H2S probes. With two-photon excitation, TPP-H2S displays high signal-to-noise ratio and sensitivity even no interference in cell growth media. As further application, TPP-H2S is applied for fast imaging of H2S in living cells and different fresh tissues by two-photon confocal microscope. Most importantly we first measured the endogenous H2S level in different viscera by vivisection and found that the distribution of endogenous H2S mostly in brain, liver and lung. The excellent sensing properties of TPP-H2S make it a practically useful tool for further studying biological roles of H2S. Copyright © 2015 Elsevier B.V. All rights reserved.

Sensitive Visual Detection of AHPND Bacteria Using Loop-Mediated Isothermal Amplification Combined with DNA-Functionalized Gold Nanoparticles as Probes

PubMed Central

Arunrut, Narong; Kampeera, Jantana; Sirithammajak, Sarawut; Sanguanrut, Piyachat; Proespraiwong, Porranee; Suebsing, Rungkarn; Kiatpathomchai, Wansika

2016-01-01

Acute hepatopancreatic necrosis disease (AHPND) is a component cause of early mortality syndrome (EMS) of shrimp. In 2013, the causative agent was found to be unique isolates of Vibrio parahaemolyticus (VPAHPND) that contained a 69 kbp plasmid (pAP1) carrying binary Pir-like toxin genes PirvpA and PirvpB. In Thailand, AHPND was first recognized in 2012, prior to knowledge of the causative agent, and it subsequently led to a precipitous drop in shrimp production. After VPAHPND was characterized, a major focus of the AHPND control strategy was to monitor broodstock shrimp and post larvae for freedom from VPAHPND by nucleic acid amplification methods, most of which required use of expensive and sophisticated equipment not readily available in a shrimp farm setting. Here, we describe a simpler but equally sensitive approach for detection of VPAHPND based on loop-mediated isothermal amplification (LAMP) combined with unaided visual reading of positive amplification products using a DNA-functionalized, ssDNA-labled nanogold probe (AuNP). The target for the special set of six LAMP primers used was the VPAHPND PirvpA gene. The LAMP reaction was carried out at 65°C for 45 min followed by addition of the red AuNP solution and further incubation at 65°C for 5 min, allowing any PirvpA gene amplicons present to hybridize with the probe. Hybridization protected the AuNP against aggregation, so that the solution color remained red upon subsequent salt addition (positive test result) while unprotected AuNP aggregated and underwent a color change from red to blue and eventually precipitated (negative result). The total assay time was approximately 50 min. The detection limit (100 CFU) was comparable to that of other commonly-used methods for nested PCR detection of VPAHPND and 100-times more sensitive than 1-step PCR detection methods (104 CFU) that used amplicon detection by electrophoresis or spectrophotometry. There was no cross reaction with DNA templates derived from non-AHPND bacteria commonly found in shrimp ponds (including other Vibrio species). The new method significantly reduced the time, difficulty and cost for molecular detection of VPAHPND in shrimp hatchery and farm settings. PMID:27003504

An ALuc-Based Molecular Tension Probe for Sensing Intramolecular Protein-Protein Interactions.

PubMed

Kim, Sung-Bae; Nishihara, Ryo; Suzuki, Koji

2016-01-01

Optical imaging of protein-protein interactions (PPIs) facilitates comprehensive elucidation of intracellular molecular events. The present protocol demonstrates an optical measure for visualizing molecular tension triggered by any PPI in mammalian cells. A unique design of single-chain probes was fabricated, in which a full-length artificial luciferase (ALuc(®)) was sandwiched between two model proteins of interest, e.g., FKBP and FRB. A molecular tension probe comprising ALuc23 greatly enhances the bioluminescence in response to varying concentrations of rapamycin, and named "tension probe (TP)." The basic probe design can be further modified towards eliminating the C-terminal end of ALuc and was found to improve signal-to-background ratios, named "combinational probe." TPs may become an important addition to the tool box of bioassays in the determination of protein dynamics of interest in mammalian cells.

Rational chemical design of the next generation of molecular imaging probes based on physics and biology: mixing modalities, colors and signals

PubMed Central

Longmire, Michelle R.; Ogawa, Mikako; Choyke, Peter L.

2012-01-01

In recent years, numerous in vivo molecular imaging probes have been developed. As a consequence, much has been published on the design and synthesis of molecular imaging probes focusing on each modality, each type of material, or each target disease. More recently, second generation molecular imaging probes with unique, multi-functional, or multiplexed characteristics have been designed. This critical review focuses on (i) molecular imaging using combinations of modalities and signals that employ the full range of the electromagnetic spectra, (ii) optimized chemical design of molecular imaging probes for in vivo kinetics based on biology and physiology across a range of physical sizes, (iii) practical examples of second generation molecular imaging probes designed to extract complementary data from targets using multiple modalities, color, and comprehensive signals (277 references). PMID:21607237

Framework for reanalysis of publicly available Affymetrix® GeneChip® data sets based on functional regions of interest.

PubMed

Saka, Ernur; Harrison, Benjamin J; West, Kirk; Petruska, Jeffrey C; Rouchka, Eric C

2017-12-06

Since the introduction of microarrays in 1995, researchers world-wide have used both commercial and custom-designed microarrays for understanding differential expression of transcribed genes. Public databases such as ArrayExpress and the Gene Expression Omnibus (GEO) have made millions of samples readily available. One main drawback to microarray data analysis involves the selection of probes to represent a specific transcript of interest, particularly in light of the fact that transcript-specific knowledge (notably alternative splicing) is dynamic in nature. We therefore developed a framework for reannotating and reassigning probe groups for Affymetrix® GeneChip® technology based on functional regions of interest. This framework addresses three issues of Affymetrix® GeneChip® data analyses: removing nonspecific probes, updating probe target mapping based on the latest genome knowledge and grouping probes into gene, transcript and region-based (UTR, individual exon, CDS) probe sets. Updated gene and transcript probe sets provide more specific analysis results based on current genomic and transcriptomic knowledge. The framework selects unique probes, aligns them to gene annotations and generates a custom Chip Description File (CDF). The analysis reveals only 87% of the Affymetrix® GeneChip® HG-U133 Plus 2 probes uniquely align to the current hg38 human assembly without mismatches. We also tested new mappings on the publicly available data series using rat and human data from GSE48611 and GSE72551 obtained from GEO, and illustrate that functional grouping allows for the subtle detection of regions of interest likely to have phenotypical consequences. Through reanalysis of the publicly available data series GSE48611 and GSE72551, we profiled the contribution of UTR and CDS regions to the gene expression levels globally. The comparison between region and gene based results indicated that the detected expressed genes by gene-based and region-based CDFs show high consistency and regions based results allows us to detection of changes in transcript formation.

The Role of Transport Phenomena in Whispering Gallery Mode Optical Biosensor Performance

NASA Astrophysics Data System (ADS)

Gamba, Jason

Whispering gallery mode (WGM) optical resonator sensors have emerged as promising tools for label-free detection of biomolecules in solution. These devices have even demonstrated single-molecule limits of detection in complex biological uids. This extraordinary sensitivity makes them ideal for low-concentration analytical and diagnostic measurements, but a great deal of work must be done toward understanding and optimizing their performance before they are capable of reliable quantitative measurents. The present work explores the physical processes behind this extreme sensitivity and how to best take advantage of them for practical applications of this technology. I begin by examining the nature of the interaction between the intense electromagnetic elds that build up in the optical biosensor and the biomolecules that bind to its surface. This work addresses the need for a coherent and thorough physical model that can be used to predict sensor behavior for a range of experimental parameters. While this knowledge will prove critical for the development of this technology, it has also shone a light on nonlinear thermo-optical and optical phenomena that these devices are uniquely suited to probing. The surprisingly rapid transient response of toroidal WGM biosensors despite sub-femtomolar analyte concentrations is also addressed. The development of asymmetric boundary layers around these devices under ow is revealed to enhance the capture rate of proteins from solution compared to the spherical sensors used previously. These lessons will guide the design of ow systems to minimize measurement time and consumption of precious sample, a key factor in any medically relevant assay. Finally, experimental results suggesting that WGM biosensors could be used to improve the quantitative detection of small-molecule biomarkers in exhaled breath condensate demonstrate how their exceptional sensitivity and transient response can enable the use of this noninvasive method to probe respiratory distress. WGM bioensors are unlike any other analytical tool, and the work presented here focuses on answering engineering questions surrounding their performance and potential.

Branched Chain RNA In Situ Hybridization for Androgen Receptor Splice Variant AR-V7 as a Prognostic Biomarker for Metastatic Castration-Sensitive Prostate Cancer.

PubMed

Saylor, Philip J; Lee, Richard J; Arora, Kshitij S; Deshpande, Vikram; Hu, Rong; Olivier, Kara; Meneely, Erika; Rivera, Miguel N; Ting, David T; Wu, Chin-Lee; Miyamoto, David T

2017-01-15

The androgen receptor (AR) mRNA splice variant AR-V7 has emerged as a predictive biomarker for response to AR-targeted therapies. There are currently no commercially available assays to detect AR splice variants. The branched chain RNA in situ hybridization (ISH) platform enables the highly sensitive detection of RNA transcripts in formalin-fixed, paraffin-embedded (FFPE) tissues. We designed a branched chain RNA ISH probe to target the unique cryptic exon CE3 of AR-V7 using multiple tiling probes. This automated ISH assay was applied to tumor tissue from two distinct clinical cohorts that we hypothesized would differ in AR-V7 status. We detected AR-V7 in all tumor samples from men with metastatic castration-resistant prostate cancer with tissue obtained after disease progression despite at least one subsequent line of hormonal therapy (abiraterone, enzalutamide, or bicalutamide; n = 12). We detected AR-V7 in just one tumor from men who had undergone prostatectomy for localized adenocarcinoma (n = 30; Gleason 4 + 5 = 9 in the AR-V7-positive sample). Given the apparent distinction between the above groups by AR-V7 signal, we analyzed pretreatment AR-V7 status as a predictive and prognostic biomarker in men with treatment-naïve metastatic disease. Patients with metastases but without detectable AR-V7 RNA at baseline had significantly longer overall survival (log-rank P = 0.044) and a trend toward superior progression-free survival (log-rank P = 0.055). Within an institutional cohort, the RNA ISH assay identified AR-V7 within FFPE tissue and may have prognostic value in metastatic castration-sensitive prostate cancer. These preliminary findings warrant further study in larger cohorts. Clin Cancer Res; 23(2); 363-9. ©2016 AACR. ©2016 American Association for Cancer Research.

HERA: Illuminating Our Early Universe

NASA Astrophysics Data System (ADS)

DeBoer, David

2014-06-01

The Hydrogen Epoch of Reionization Arrays (HERA) roadmap is a staged plan for using the unique properties of the 21cm line from neutral hydrogen to probe our cosmic dawn, from the birth of the first stars and black holes, through the full reionization of the primordial intergalactic medium (IGM). HERA is a collaboration between the Precision Array Probing the Epoch of Reionization (PAPER), US-Murchison Widefield Array (MWA), and MIT Epoch of Reionization (MITEOR) teams.The first phase of the HERA roadmap entailed the operation of the PAPER and MWA telescopes to explore techniques and designs required to detect the primordial HI signal in the presence of radio continuum foreground emission some four orders of magnitude brighter. Studies with PAPER and the MWA have led to a new understanding of the interplay of foreground and instrumental systematics in the context of a three-dimensional cosmological intensity-mapping experiment. We are now able to remove foregrounds to the limits of our sensitivity with these instruments, culminating in the first physically meaningful upper limits on the power spectrum of 2 cm emission from reionization.Building on this understanding, the next stage of HERA entails a new 14m diameter antenna element that is optimized both for sensitivity and for minimizing foreground systematics. Arranging these elements in a compact hexagonal grid yields an array that facilitates calibration, leverages proven foreground removal techniques, and is scalable to large collecting areas. The HERA phase II will be located in the radio quiet environment of the SKA site in Karoo, South Africa, and have a sensitivity close to two orders of magnitude better than PAPER and the MWA, with broader frequency coverage, HERA can paint an uninterrupted picture through reionization, back to the end of the Dark Ages.This paper will present a summary of the current understanding of the signal characteristics and measurements and describe this planned HERA telescope to be built to detect and characterize the EoR power spectrum.

Multiplex diagnosis of viral infectious diseases (AIDS, hepatitis C, and hepatitis A) based on point of care lateral flow assay using engineered proteinticles.

PubMed

Lee, Jong-Hwan; Seo, Hyuk Seong; Kwon, Jung-Hyuk; Kim, Hee-Tae; Kwon, Koo Chul; Sim, Sang Jun; Cha, Young Joo; Lee, Jeewon

2015-07-15

Lateral flow assay (LFA) is an attractive method for rapid, simple, and cost-effective point of care diagnosis. For LFA-based multiplex diagnosis of three viral intractable diseases (acquired immune deficiency syndrome and hepatitis C and A), here we developed proteinticle-based 7 different 3D probes that display different viral antigens on their surface, which were synthesized in Escherichia coli by self-assembly of human ferritin heavy chain that was already engineered by genetically linking viral antigens to its C-terminus. Each of the three test lines on LFA strip contains the proteinticle probes to detect disease-specific anti-viral antibodies. Compared to peptide probes, the proteinticle probes were evidently more sensitive, and the proteinticle probe-based LFA successfully diagnosed all the 20 patient sera per each disease without a false negative signal, whereas the diagnostic sensitivities in the peptide probe-based LFAs were 65-90%. Duplex and triplex assays performed with randomly mixed patient sera gave only true positive signals for all the 20 serum mixtures without any false positive signals, indicating 100% sensitivity and 100% specificity. It seems that on the proteinticle surface the antigenic peptides have homogeneous orientation and conformation without inter-peptide clustering and hence lead to the enhanced diagnostic performance with solving the problems of traditional diagnostic probes. Although the multiplex diagnosis of three viral diseases above was demonstrated as proof-of-concept here, the proposed LFA system can be applied to multiplex point of care diagnosis of other intractable diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbon nanotube scanning probe for imaging in aqueous environment

NASA Technical Reports Server (NTRS)

Stevens, Ramsey M.; Nguyen, Cattien V.; Meyyappan, M.

2004-01-01

Carbon nanotubes (CNTs) used as a probe for scanning probe microscopy has become one of the many potential usages of CNTs that is finding real applications in scientific research and industrial communities. It has been proposed that the unique mechanical buckling properties of the CNT would lessen the imaging force exerted on the sample and, thus, make CNT scanning probes ideal for imaging soft materials, including biological samples in liquid environments. The hydrophobic nature of the CNT graphitic sidewall is clearly chemically incompatible with the aqueous solution requirements in some biological imaging applications. In this paper, we present electron micrograph results demonstrating the instability of CNT scanning probes when submerged in aqueous solution. Moreover, we also introduce a novel approach to resolve this chemical incompatibility problem. By coating the CNT probe with ethylenediamine, thus rendering the CNT probe less hydrophobic, we demonstrate the liquid imaging capability of treated CNT probes. Experimental data for imaging in aqueous solutions are presented, which include an ultrathin Ir film and DNA molecules on a mica surface.

Fluorescent Probes for Sensitive and Selective Detection of pH Changes in Live Cells in Visible and Near-infrared Channels.

PubMed

Fang, Mingxi; Adhikari, Rashmi; Bi, Jianheng; Mazi, Wafa; Dorh, Nethaniah; Wang, Jianbo; Conner, Nathan; Ainsley, Jon; Karabencheva-Christova, Tatyana G; Luo, Fen-Tair; Tiwari, Ashutosh; Liu, Haiying

2017-12-28

We report five fluorescent probes based on coumarin-hybridized fluorescent dyes with spirolactam ring structures (A-E) to detect pH changes in live cell by monitoring visible and near-infrared fluorescence changes. Under physiological or basic conditions, the fluorescent probes A, B, C, D and E preserve their spirolactam ring-closed forms and only display fluorescent peaks in the visible region corresponding to coumarin moieties at 497, 483, 498, 497 and 482 nm, respectively. However, at acidic pH, the rings of the spirolactam forms of the fluorescent probes A, B, C, D and E open up, generating new near-infrared fluorescence peaks at 711, 696, 707, 715, and 697 nm, respectively, through significantly extended π-conjugation to coumarin moieties of the fluorophores. The fluorescent probes B and E can be applied to visualize pH changes by monitoring visible as well as near-infrared fluorescence changes. This helps avoid fluorescence imaging blind spots at neutral or basic pH, which typical pH fluorescent probes encounter. The probes exhibit high sensitivity to pH changes, excellent photostability, low auto-fluorescence background and good cell membrane permeability.

Probing Protein Structure and Folding in the Gas Phase by Electron Capture Dissociation

NASA Astrophysics Data System (ADS)

Schennach, Moritz; Breuker, Kathrin

2015-07-01

The established methods for the study of atom-detailed protein structure in the condensed phases, X-ray crystallography and nuclear magnetic resonance spectroscopy, have recently been complemented by new techniques by which nearly or fully desolvated protein structures are probed in gas-phase experiments. Electron capture dissociation (ECD) is unique among these as it provides residue-specific, although indirect, structural information. In this Critical Insight article, we discuss the development of ECD for the structural probing of gaseous protein ions, its potential, and limitations.

Using Environment-Sensitive Fluorescent Probes to Characterize Liquid-Liquid Phase Separation in Supersaturated Solutions of Poorly Water Soluble Compounds.

PubMed

Raina, Shweta A; Alonzo, David E; Zhang, Geoff G Z; Gao, Yi; Taylor, Lynne S

2015-11-01

Highly supersaturated aqueous solutions of poorly soluble compounds can undergo liquid-liquid phase separation (LLPS) when the concentration exceeds the "amorphous solubility". This phenomenon has been widely observed during high throughput screening of new molecular entities as well as during the dissolution of amorphous solid dispersions. In this study, we have evaluated the use of environment-sensitive fluorescence probes to investigate the formation and properties of the non-crystalline drug-rich aggregates formed in aqueous solutions as a result of LLPS. Six different environment-sensitive fluorophores were employed to study LLPS in highly supersaturated solutions of several model compounds, all dihydropyridine derivatives. Each fluoroprobe exhibited a large hypsochromic shift with decreasing environment polarity. Upon drug aggregate formation, the probes partitioned into the drug-rich phase and exhibited changes in emission wavelength and intensity consistent with sensing a lower polarity environment. The LLPS onset concentrations determined using the fluorescence measurements were in good agreement with light scattering measurements as well as theoretically estimated amorphous solubility values. Environment-sensitive fluorescence probes are useful to help understand the phase behavior of highly supersaturated aqueous solutions, which in turn is important in the context of developing enabling formulations for poorly soluble compounds.

Application of porous metal enrichment probe sampling to single cell analysis using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).

PubMed

Fu, Qiang; Tang, Jun; Cui, Meng; Xing, Junpeng; Liu, Zhiqiang; Liu, Shuying

2016-01-01

There is an increasing need for analyzing metabolism in a single cell, which is important to understand the nature of cellular heterogeneity, disease, growth and specialization, etc. However, single cell analysis is often challenging for the traces of samples. In the present study, porous metal enrichment probe sampling combined with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) has been applied for in situ analysis of live onion epidemic cell. Porous probe, treated by corroding copper wire with HCl, was directly inserted into a single cell to get cell solution. A self-made linear actuator was enough to control the penetration of probe into the target cell accurately. Then samples on the tip of probe were eluted and detected by a commercial MALDI-TOF-MS directly. The formation of porous microstructure on the probe surface increased the adsorptive capacity of cell solution. The sensitivity of porous probe sampling was 6 times higher than uncorroded probes generally. This method provides a sensitive and convenient way for the sampling and detection of single cell solution. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Detection of heavy metal ions in contaminated water by surface plasmon resonance based optical fibre sensor using conducting polymer and chitosan.

PubMed

Verma, Roli; Gupta, Banshi D

2015-01-01

Optical fibre surface plasmon resonance (SPR) based sensor for the detection of heavy metal ions in the drinking water is designed. Silver (Ag) metal and indium tin oxide (ITO) are used for the fabrication of the SPR probe which is further modified with the coating of pyrrole and chitosan composite. The sensor works on the wavelength interrogation technique and is capable of detecting trace amounts of Cd(2+), Pb(2+), and Hg(2+) heavy metal ions in contaminated water. Four types of sensing probes are fabricated and characterised for heavy metal ions out of these pyrrole/chitosan/ITO/Ag coated probe is found to be highly sensitive among all other probes. Further, the cadmium ions bind strongly to the sensing surface than other ions and due to this the sensor is highly sensitive for Cd(2+) ions. The sensor's performance is best for the low concentrations of heavy metal ions and its sensitivity decreases with the increasing concentration of heavy metal ions. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Smart Detection System Based on Specific Magnetic and Rolling Cycle Amplification Signal-Amplified Dual-Aptamers to Accurately Monitor Minimal Residual Diseases in Patients with T-ALL.

PubMed

Li, Xa; Zhou, Bo; Zhao, Zilong; Hu, Zixi; Zhou, Sufang; Yang, Nuo; Huang, Yong; Zhang, Zhenghua; Su, Jing; Lan, Dan; Qin, Xue; Meng, Jinyu; Zheng, Duo; He, Jian; Huang, Xianing; Zhao, Jing; Zhang, Zhiyong; Tan, Weihong; Lu, Xiaoling; Zhao, Yongxiang

2016-12-01

It is a major clinical challenge for clinicians how to early find out minimal residual diseases (MRD) of leukemia. Here, we developed a smart detection system for MRD involving magnetic aptamer sgc8 probe (M-sgc8 probe) to capture CEM cells and rolling cycle amplification probe (RCA-sgc8 probe) to initiate RCA, producing a single-stranded tandem repeated copy of the circular template. The DNA products were hybridized with molecular beacon to generate the amplified fluorescence signal. An in vitro model to mimic MRD was established to evaluate the sensitivity of the smart detection system. The smart detection system was used to detect MRD in patients with T-ALL peri-chemotherapy, which could not only specifically captured T-ALL cells, but also significantly amplified fluorescence signals on them. The sensitivity was 1/20,000. These results indicate that the smart detection system with high specificity and sensitivity could more efficiently monitor the progress of T-ALL peri-chemotherapy.

Evaluation of a novel ultra-sensitive nanoparticle probe-based assay for ricin detection.

PubMed

Yin, Hui-qiong; Jia, Min-xian; Shi, Li-jun; Liu, Jun; Wang, Rui; Lv, Mao-min; Ma, Yu-yuan; Zhao, Xiong; Zhang, Jin-gang

2014-01-01

A gold nanoparticle (GNP) probe-based assay (GNPA) modified from the bio-barcode assay (BCA) was developed for ultrasensitive detection of ricin, a potential biothreat agent. In the GNPA, a chain of ricin was captured by a GNP probe coated with polyclonal antibodies and single-stranded signal DNA. A magnetic microparticle (MMP) probe coated with ricin A chain monoclonal antibody was then added to form an immuno-complex. After being magnetically separated, the immuno-complex containing the single-stranded signal DNA was characterized by PCR and real-time PCR. A detection limit of 10(-2) fg/ml was determined for the ricin A chain; this is eight orders of magnitude more sensitive than that achieved with an ELISA and two orders more sensitive than that obtained with the BCA. The coefficients of variation (CV) of the intra- and inter-assay values ranged from 3.82-6.46%. The results here show that this novel assay is an ultrasensitive method for detection of ricin proteins and may be suitable for the ultrasensitive detection of other proteins.

A Highly Sensitive Fluorogenic Probe for Imaging Glycoproteins and Mucine Activity in Live Cells in the Near-Infrared Region.

PubMed

Samaniego Lopez, Cecilia; Hebe Martínez, Jimena; Uhrig, María Laura; Coluccio Leskow, Federico; Spagnuolo, Carla Cecilia

2018-04-25

A novel fluorescent molecular probe is reported, which is able to detect glycoproteins, especially mucins, with high sensitivity and with a turn-on response along with a large Stokes shift (>130 nm), within the biologically active window. The probe contains an aminotricarbocyanine as the fluorescent reporter with a linked benzoboroxole as the recognition unit, which operates through a dynamic covalent reaction between the boronic hemiester residue of the receptor and cis-diols of the analyte. The superior selectivity of the probe is displayed by the labeling of mucins present in Calu-3 cells. The new benzoboroxole fluorescent derivative gathers together key properties to make it a highly rated molecular probe: specificity, excellent solubility in water, and off-on near infrared emission. This probe is expected to be an excellent tool for imaging intracellular mucin to evaluate mucus-related diseases as well as a sensing strategy towards glycosylated structures with a high potential for theranostics approaches in biological samples. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly selective and sensitive near-infrared-fluorescent probes for the detection of cellular hydrogen sulfide and the imaging of H2S in mice.

PubMed

Wu, Haixia; Krishnakumar, Saarangan; Yu, Jie; Liang, Dong; Qi, Hongyi; Lee, Zheng-Wei; Deng, Lih-Wen; Huang, Dejian

2014-12-01

Herein, we report the development of two fluorescent probes for the highly selective and sensitive detection of H2S. The probes take advantage of a Cu(II)-cyclen complex, which acts as a reaction center for H2S and as a quencher of BODIPY (boron-dipyrromethene)-based fluorophores with emissions at 765 and 680 nm, respectively. These non-fluorescent probes could only be turned on by the addition of H2 S, and not by other potentially interfering biomolecules, including reactive oxygen species, cysteine, and glutathione. In a chemical system, both probes detected H2S with a detection limit of 80 nM. The probes were successfully used for the endogenous detection of H2S in HEK 293 cells, for measuring the H2S-release activity of dietary organosulfides in MCF-7 cells, and for the in vivo imaging of H2S in mice. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Use of the polymerase chain reaction to directly detect malaria parasites in blood samples from the Venezuelan Amazon.

PubMed

Laserson, K F; Petralanda, I; Hamlin, D M; Almera, R; Fuentes, M; Carrasquel, A; Barker, R H

1994-02-01

We have examined the reproducibility, sensitivity, and specificity of detecting Plasmodium falciparum using the polymerase chain reaction (PCR) and the species-specific probe pPF14 under field conditions in the Venezuelan Amazon. Up to eight samples were field collected from each of 48 consenting Amerindians presenting with symptoms of malaria. Sample processing and analysis was performed at the Centro Amazonico para la Investigacion y Control de Enfermedades Tropicales Simon Bolivar. A total of 229 samples from 48 patients were analyzed by PCR methods using four different P. falciparum-specific probes. One P. vivax-specific probe and by conventional microscopy. Samples in which results from PCR and microscopy differed were reanalyzed at a higher sensitivity by microscopy. Results suggest that microscopy-negative, PCR-positive samples are true positives, and that microscopy-positive and PCR-negative samples are true negatives. The sensitivity of the DNA probe/PCR method was 78% and its specificity was 97%. The positive predictive value of the PCR method was 88%, and the negative predictive value was 95%. Through the analysis of multiple blood samples from each individual, the DNA probe/PCR methodology was found to have an inherent reproducibility that was highly statistically significant.

Development and Use of Integrated Microarray-Based Genomic Technologies for Assessing Microbial Community Composition and Dynamics

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

Zhou, J.; Wu, L.; Gentry, T.

2006-04-05

To effectively monitor microbial populations involved in various important processes, a 50-mer-based oligonucleotide microarray was developed based on known genes and pathways involved in: biodegradation, metal resistance and reduction, denitrification, nitrification, nitrogen fixation, methane oxidation, methanogenesis, carbon polymer decomposition, and sulfate reduction. This array contains approximately 2000 unique and group-specific probes with <85% similarity to their non-target sequences. Based on artificial probes, our results showed that at hybridization conditions of 50 C and 50% formamide, the 50-mer microarray hybridization can differentiate sequences having <88% similarity. Specificity tests with representative pure cultures indicated that the designed probes on the arrays appearedmore » to be specific to their corresponding target genes. Detection limits were about 5-10ng genomic DNA in the absence of background DNA, and 50-100ng ({approx}1.3{sup o} 10{sup 7} cells) in the presence background DNA. Strong linear relationships between signal intensity and target DNA and RNA concentration were observed (r{sup 2} = 0.95-0.99). Application of this microarray to naphthalene-amended enrichments and soil microcosms demonstrated that composition of the microflora varied depending on incubation conditions. While the naphthalene-degrading genes from Rhodococcus-type microorganisms were dominant in enrichments, the genes involved in naphthalene degradation from Gram-negative microorganisms such as Ralstonia, Comamonas, and Burkholderia were most abundant in the soil microcosms (as well as those for polyaromatic hydrocarbon and nitrotoluene degradation). Although naphthalene degradation is widely known and studied in Pseudomonas, Pseudomonas genes were not detected in either system. Real-time PCR analysis of 4 representative genes was consistent with microarray-based quantification (r{sup 2} = 0.95). Currently, we are also applying this microarray to the study of several different microbial communities and processes at the NABIR-FRC in Oak Ridge, TN. One project involves the monitoring of the development and dynamics of the microbial community of a fluidized bed reactor (FBR) used for reducing nitrate and the other project monitors microbial community responses to stimulation of uranium reducing populations via ethanol donor additions in situ and in a model system. Additionally, we are developing novel strategies for increasing microarray hybridization sensitivity. Finally, great improvements to our methods of probe design were made by the development of a new computer program, CommOligo. CommOligo designs unique and group-specific oligo probes for whole-genomes, metagenomes, and groups of environmental sequences and uses a new global alignment algorithm to design single or multiple probes for each gene or group. We are now using this program to design a more comprehensive functional gene array for environmental studies. Overall, our results indicate that the 50mer-based microarray technology has potential as a specific and quantitative tool to reveal the composition of microbial communities and their dynamics important to processes within contaminated environments.« less

Outer planet atmospheric entry probes - An overview of technology readiness

NASA Technical Reports Server (NTRS)

Vojvodich, N. S.; Reynolds, R. T.; Grant, T. L.; Nachtsheim, P. R.

1975-01-01

Entry probe systems for characterizing, by in situ measurements, the atmospheric properties, chemical composition, and cloud structure of the planets Saturn, Uranus, and Jupiter are examined from the standpoint of unique mission requirements, associated subsystem performance, and degree of commonality of design. Past earth entry vehicles (PAET) and current planetary spacecraft (Pioneer Venus probes and Viking lander) are assessed to identify the extent of potential subsystem inheritance, as well as to establish the significant differences, in both form and function, relative to outer planet requirements. Recent research results are presented and reviewed for the most critical probe technology areas, including: science accommodation, telecommunication, and entry heating and thermal protection. Finally presented is a brief discussion of the use of decision analysis techniques for quantifying various probe heat-shield test alternatives and performance risk.

Supercontinuum white light lasers for flow cytometry

PubMed Central

Telford, William G.; Subach, Fedor V.; Verkhusha, Vladislav V.

2009-01-01

Excitation of fluorescent probes for flow cytometry has traditionally been limited to a few discrete laser lines, an inherent limitation in our ability to excite the vast array of fluorescent probes available for cellular analysis. In this report, we have used a supercontinuum (SC) white light laser as an excitation source for flow cytometry. By selectively filtering the wavelength of interest, almost any laser wavelength in the visible spectrum can be separated and used for flow cytometric analysis. The white light lasers used in this study were integrated into a commercial flow cytometry platform, and a series of high-transmission bandpass filters used to select wavelength ranges from the blue (~480 nm) to the long red (>700 nm). Cells labeled with a variety of fluorescent probes or expressing fluorescent proteins were then analyzed, in comparison with traditional lasers emitting at wavelengths similar to the filtered SC source. Based on a standard sensitivity metric, the white light laser bandwidths produced similar excitation levels to traditional lasers for a wide variety of fluorescent probes and expressible proteins. Sensitivity assessment using fluorescent bead arrays confirmed that the SC laser and traditional sources resulted in similar levels of detection sensitivity. Supercontinuum white light laser sources therefore have the potential to remove a significant barrier in flow cytometric analysis, namely the limitation of excitation wavelengths. Almost any visible wavelength range can be made available for excitation, allowing access to virtually any fluorescent probe, and permitting “fine-tuning” of excitation wavelength to particular probes. PMID:19072836

Piezoresistor-equipped fluorescence-based cantilever probe for near-field scanning.

PubMed

Kan, Tetsuo; Matsumoto, Kiyoshi; Shimoyama, Isao

2007-08-01

Scanning near-field optical microscopes (SNOMs) with fluorescence-based probes are promising tools for evaluating the optical characteristics of nanoaperture devices used for biological investigations, and this article reports on the development of a microfabricated fluorescence-based SNOM probe with a piezoresistor. The piezoresistor was built into a two-legged root of a 160-microm-long cantilever. To improve the displacement sensitivity of the cantilever, the piezoresistor's doped area was shallowly formed on the cantilever surface. A fluorescent bead, 500 nm in diameter, was attached to the bottom of the cantilever end as a light-intensity-sensitive material in the visible-light range. The surface of the scanned sample was simply detected by the probe's end being displaced by contact with the sample. Measuring displacements piezoresistively is advantageous because it eliminates the noise arising from the use of the optical-lever method and is free of any disturbance in the absorption or the emission spectrum of the fluorescent material at the probe tip. The displacement sensitivity was estimated to be 6.1 x 10(-6) nm(-1), and the minimum measurable displacement was small enough for near-field measurement. This probe enabled clear scanning images of the light field near a 300 x 300 nm(2) aperture to be obtained in the near-field region where the tip-sample distance is much shorter than the light wavelength. This scanning result indicates that the piezoresistive way of tip-sample distance regulation is effective for characterizing nanoaperture optical devices.

Development of a multiplex probe combination-based one-step real-time reverse transcription-PCR for NA subtype typing of avian influenza virus.

PubMed

Sun, Zhihao; Qin, Tao; Meng, Feifei; Chen, Sujuan; Peng, Daxin; Liu, Xiufan

2017-10-18

Nine influenza virus neuraminidase (NA) subtypes have been identified in poultry and wild birds. Few methods are available for rapid and simple NA subtyping. Here we developed a multiplex probe combination-based one-step real-time reverse transcriptase PCR (rRT-PCR) to detect nine avian influenza virus NA subtypes. Nine primer-probe pairs were assigned to three groups based on the different fluorescent dyes of the probes (FAM, HEX, or Texas Red). Each probe detected only one NA subtype, without cross reactivity. The detection limit was less than 100 EID 50 or 100 copies of cDNA per reaction. Data obtained using this method with allantoic fluid samples isolated from live bird markets and H9N2-infected chickens correlated well with data obtained using virus isolation and sequencing, but was more sensitive. This new method provides a specific and sensitive alternative to conventional NA-subtyping methods.

Piezo-thermal Probe Array for High Throughput Applications

PubMed Central

Gaitas, Angelo; French, Paddy

2012-01-01

Microcantilevers are used in a number of applications including atomic-force microscopy (AFM). In this work, deflection-sensing elements along with heating elements are integrated onto micromachined cantilever arrays to increase sensitivity, and reduce complexity and cost. An array of probes with 5–10 nm gold ultrathin film sensors on silicon substrates for high throughput scanning probe microscopy is developed. The deflection sensitivity is 0.2 ppm/nm. Plots of the change in resistance of the sensing element with displacement are used to calibrate the probes and determine probe contact with the substrate. Topographical scans demonstrate high throughput and nanometer resolution. The heating elements are calibrated and the thermal coefficient of resistance (TCR) is 655 ppm/K. The melting temperature of a material is measured by locally heating the material with the heating element of the cantilever while monitoring the bending with the deflection sensing element. The melting point value measured with this method is in close agreement with the reported value in literature. PMID:23641125

Determination of ethambutol by a sensitive fluorescent probe

NASA Astrophysics Data System (ADS)

Wu, Wen-Ying; Yang, Ji-Yuan; Du, Li-Ming; Wu, Hao; Li, Chang-Feng

2011-08-01

The competitive reaction between ethambutol and two fluorescent probes (i.e., berberine and palmatine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorometry. The CB[7] reacts with these probes to form stable complexes, and the fluorescence intensity of the complexes is greatly enhanced. In addition, the excitation and emission wavelengths of their complexes moved to wavelengths of 343 nm and 495 nm, respectively. However, the addition of ethambutol dramatically quenches the fluorescence intensity of the two complexes. Accordingly, a couple of new fluorescence quenching methods for the determination of ethambutol were established. The methods can be applied for quantifying ethambutol. A linear relationship between the fluorescence quenching values (Δ F) and ethambutol concentration exists in the range of 5.0-1000.0 ng mL -1, with a correlation coefficient ( r) of 0.9997. The detection limit is 1.7 ng mL -1. The fluorescent probe of berberine has higher sensitivity than palmatine. This paper also discusses the mechanism of fluorescence indicator probes.

Detection of proteins using a colorimetric bio-barcode assay.

PubMed

Nam, Jwa-Min; Jang, Kyung-Jin; Groves, Jay T

2007-01-01

The colorimetric bio-barcode assay is a red-to-blue color change-based protein detection method with ultrahigh sensitivity. This assay is based on both the bio-barcode amplification method that allows for detecting miniscule amount of targets with attomolar sensitivity and gold nanoparticle-based colorimetric DNA detection method that allows for a simple and straightforward detection of biomolecules of interest (here we detect interleukin-2, an important biomarker (cytokine) for many immunodeficiency-related diseases and cancers). The protocol is composed of the following steps: (i) conjugation of target capture molecules and barcode DNA strands onto silica microparticles, (ii) target capture with probes, (iii) separation and release of barcode DNA strands from the separated probes, (iv) detection of released barcode DNA using DNA-modified gold nanoparticle probes and (v) red-to-blue color change analysis with a graphic software. Actual target detection and quantification steps with premade probes take approximately 3 h (whole protocol including probe preparations takes approximately 3 days).

Large-Area, Ensemble Molecular Electronics: Motivation and Challenges.

PubMed

Vilan, Ayelet; Aswal, Dinesh; Cahen, David

2017-03-08

We review charge transport across molecular monolayers, which is central to molecular electronics (MolEl), using large-area junctions (NmJ). We strive to provide a wide conceptual overview of three main subtopics. First, a broad introduction places NmJ in perspective to related fields of research and to single-molecule junctions (1mJ) in addition to a brief historical account. As charge transport presents an ultrasensitive probe for the electronic perfection of interfaces, in the second part ways to form both the monolayer and the contacts are described to construct reliable, defect-free interfaces. The last part is dedicated to understanding and analyses of current-voltage (I-V) traces across molecular junctions. Notwithstanding the original motivation of MolEl, I-V traces are often not very sensitive to molecular details and then provide a poor probe for chemical information. Instead, we focus on how to analyze the net electrical performance of molecular junctions, from a functional device perspective. Finally, we point to creation of a built-in electric field as a key to achieve functionality, including nonlinear current-voltage characteristics that originate in the molecules or their contacts to the electrodes. This review is complemented by a another review that covers metal-molecule-semiconductor junctions and their unique hybrid effects.

Effective and efficient detection of pH fluctuations based on ratiometric metallic-ciprofloxacin architectures

NASA Astrophysics Data System (ADS)

Wang, Zhuosen; Gao, Jinwei; Zhang, Kaibo; Mai, Zhihong; Wang, Qianming

2018-07-01

The availability of lanthanide ciprofloxacin complexes and the exploration of efficient new ways to the target species have made fluorescent signals as essential tools for chemical sensing. Both terbium (III) and europium (III) compounds possess easily distinguished, line-like emission bands occurring in the green and red region respectively. Based on the steps of ionizations and the coordination structure changes, the two molecular probes give rise to unique pH-sensitivities at different conditions. The photoluminescence properties of the mixture for the two complexes are demonstrated. At pH from 3 to 6, the Eu(III) emission is found to be less affected and the solution emits blue light in acidic environment (pH = 3). The terbium (III) characteristic luminescence exhibited off-on changes within a narrow pH range (pH = 5-6). Further spectroscopic pH titrations (pH from 6 to 10) are performed and the Eu (III) red emission has been significantly improved. The molecular-based probes have excellent water solubility, negligible cytotoxicity and enough permeability to across cell membrane. Such pH-responsive performance has been carried out for the investigation of intracellular pH measurement and these novel pH indicators were considered to be suitable for detecting bio-medical samples.

Quantitative imaging of gold nanoparticle distribution in a tumor-bearing mouse using benchtop x-ray fluorescence computed tomography

PubMed Central

Manohar, Nivedh; Reynoso, Francisco J.; Diagaradjane, Parmeswaran; Krishnan, Sunil; Cho, Sang Hyun

2016-01-01

X-ray fluorescence computed tomography (XFCT) is a technique that can identify, quantify, and locate elements within objects by detecting x-ray fluorescence (characteristic x-rays) stimulated by an excitation source, typically derived from a synchrotron. However, the use of a synchrotron limits practicality and accessibility of XFCT for routine biomedical imaging applications. Therefore, we have developed the ability to perform XFCT on a benchtop setting with ordinary polychromatic x-ray sources. Here, we report our postmortem study that demonstrates the use of benchtop XFCT to accurately image the distribution of gold nanoparticles (GNPs) injected into a tumor-bearing mouse. The distribution of GNPs as determined by benchtop XFCT was validated using inductively coupled plasma mass spectrometry. This investigation shows drastically enhanced sensitivity and specificity of GNP detection and quantification with benchtop XFCT, up to two orders of magnitude better than conventional x-ray CT. The results also reaffirm the unique capabilities of benchtop XFCT for simultaneous determination of the spatial distribution and concentration of nonradioactive metallic probes, such as GNPs, within the context of small animal imaging. Overall, this investigation identifies a clear path toward in vivo molecular imaging using benchtop XFCT techniques in conjunction with GNPs and other metallic probes. PMID:26912068

“RaMassays”: Synergistic Enhancement of Plasmon-Free Raman Scattering and Mass Spectrometry for Multimodal Analysis of Small Molecules

PubMed Central

Alessandri, Ivano; Vassalini, Irene; Bertuzzi, Michela; Bontempi, Nicolò; Memo, Maurizio; Gianoncelli, Alessandra

2016-01-01

SiO2/TiO2 core/shell (T-rex) beads were exploited as “all-in-one” building-block materials to create analytical assays that combine plasmon-free surface enhanced Raman scattering (SERS) and surface assisted laser desorption/ionization (SALDI) mass spectrometry (RaMassays). Such a multi-modal approach relies on the unique optical properties of T-rex beads, which are able to harvest and manage light in both UV and Vis range, making ionization and Raman scattering more efficient. RaMassays were successfully applied to the detection of small (molecular weight, M.W. <400 Da) molecules with a key relevance in biochemistry and pharmaceutical analysis. Caffeine and cocaine were utilized as molecular probes to test the combined SERS/SALDI response of RaMassays, showing excellent sensitivity and reproducibility. The differentiation between amphetamine/ephedrine and theophylline/theobromine couples demonstrated the synergistic reciprocal reinforcement of SERS and SALDI. Finally, the conversion of L-tyrosine in L-DOPA was utilized to probe RaMassays as analytical tools for characterizing reaction intermediates without introducing any spurious effects. RaMassays exhibit important advantages over plasmonic nanoparticles in terms of reproducibility, absence of interference and potential integration in multiplexed devices. PMID:27698368

[Development of fluorescent probes for bone imaging in vivo ~Fluorescent probes for intravital imaging of osteoclast activity~.

PubMed

Minoshima, Masafumi; Kikuchi, Kazuya

Fluorescent molecules are widely used as a tool to directly visualize target biomolecules in vivo. Fluorescent probes have the advantage that desired function can be rendered based on rational design. For bone-imaging fluorescent probes in vivo, they should be delivered to bone tissue upon administration. Recently, a fluorescent probe for detecting osteoclast activity was developed. The fluorescent probe has acid-sensitive fluorescence property, specific delivery to bone tissue, and durability against laser irradiation, which enabled real-time intravital imaging of bone-resorbing osteoclasts for a long period of time.

Investigation of eddy current examination on OD fatigue crack for steam generator tubes

NASA Astrophysics Data System (ADS)

Kong, Yuying; Ding, Boyuan; Li, Ming; Liu, Jinhong; Chen, Huaidong; Meyendorf, Norbert G.

2015-03-01

The opening width of fatigue crack was very small, and conventional Bobbin probe was very difficult to detect it in steam generator tubes. Different sizes of 8 fatigue cracks were inspected using bobbin probe rotating probe. The analysis results showed that, bobbin probe was not sensitive for fatigue crack even for small through wall crack mixed with denting signal. On the other hand, the rotating probe was easily to detect all cracks. Finally, the OD phase to depth curve for fatigue crack using rotating probe was established and the results agreed very well with the true crack size.

"Reactive" optical sensor for Hg2+ and its application in environmental aqueous media and biological systems.

PubMed

Chen, Zhi; Chen, Jiayun; Pan, Dong; Li, Hongwei; Yao, Yunhui; Lyu, Zu; Yang, Liting; Ma, Li-Jun

2017-03-01

A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. Sensor 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity (detection limits are 27.6 nM (5.5 ppb) and 6.9 nM (1.4 ppb), respectively) in neutral buffer solution. To test its applicability in the environment, sensor 1 was applied to quantify and visualize low levels of Hg 2+ in tap water and river water samples. The results indicate sensor 1 is a highly sensitive fluorescent sensor for Hg 2+ with a detection limit of 1.7 ppb in tap water and river water. Moreover, sensor 1 is a convenient visualizing sensor for low levels of Hg 2+ (0.1 ppm) in water environment (from colorless to light pink). In addition, sensor 1 shows good potential as a fluorescent visualizing sensor for Hg 2+ in fetal bovine serum and living 293T cells. The results indicate that sensor 1 shows good potential as a highly sensitive sensor for the detection of Hg 2+ in environmental and biological samples. Graphical Abstract A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity in water environment. And it is a convenient visualizing probe for low levels of Hg 2+ in environment aqueous media, fetal bovine serum and living 293T cells.

Evaluation of Forces on the Welding Probe of the Automated Retractable Pin-Tool (RPT)

NASA Technical Reports Server (NTRS)

Ding, R. J.

2001-01-01

The NASA invention entitled 'The Hydraulic Controlled Auto-Adjustable Pin Tool for Friction Stir Welding' (US Patent 5,893,507), better known as the Retractable Pin-Tool (RPT), has been instrumented with a load-detecting device allowing the forces placed on the welding probe to be measured. As the welding probe is plunged into the material, the forces placed on the probe can now be characterized. Of particular interest are those forces experienced as the welding probe comes within close proximity to the back-up anvil. For a given material, it is believed that unique forces are generated relative to the distance between the welding probe and the anvil. The forces have been measured and characterized for several materials, and correlations have been made between these forces and the pin's position relative to the backside of the weld material.

SEM probe of IC radiation sensitivity

NASA Technical Reports Server (NTRS)

Gauthier, M. K.; Stanley, A. G.

1979-01-01

Scanning Electron Microscope (SEM) used to irradiate single integrated circuit (IC) subcomponent to test for radiation sensitivity can localize area of IC less than .03 by .03 mm for determination of exact location of radiation sensitive section.

Development of an ultrasensitive PCR assay for polycyclic musk determination in fish.

PubMed

Zhang, Xiaohan; Zhuang, Huisheng

2018-05-01

Polycyclic musks (PCMs) in the aquatic environment and organisms have become an emerging environmental issue because of their potential risk. The most used method for polycyclic musk determination is gas chromatography-mass spectrometry (GC-MS) with different sample extractions, which are somewhat expensive to operate, complex and laborious. In this study, a novel and ultrasensitive real-time polymerase chain reaction (PCR) assay with multiple signal amplification of carboxylic-DNA by gold nanoparticle-polyamidoamine conjugation (Au-PAMAM) was developed for determining polycyclic musks in fish. Hapten and immunogen were specially prepared. Polyclonal antibodies were produced based on the optimal immunisation, and the antibodies were characterised. Due to PAMAM's unique nanostructure of numerous functional amino groups, polyclonal antibody and carboxylic-DNA were immobilised by Au-PAMAM conjugation to develop the antibody-Au-PAMAM-DNA probes, which were used as a signal DNA amplifier in the PCR system. Compared with real-time immuno-PCR, this biological probe-amplified immuno-PCR (BPAI-PCR) assay had higher sensitivity due to the probes' higher ratio of signal DNA. Finally, the BPAI-PCR assay was applied to analyse AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene,Tonalide) concentrations in fish samples in the range from 1 pg/L to 10 ng/L, giving an of LOD 0.61 pg/L. In general, due to the specificity of the antibody and novel nanoprobe design, this BPAI-PCR assay provided a potential way for trace analysis of AHTN in the aquatic organisms. The high concentrations of AHTN found in cultivated fish should encourage further toxicological studies.

Electronic Raman Scattering as an Ultra-Sensitive Probe of Strain Effects in Semiconductors

NASA Astrophysics Data System (ADS)

Mascarenhas, Angelo; Fluegel, Brian; Beaton, Dan

Semiconductor strain engineering has become a critical feature of high-performance electronics due to the significant device performance enhancements it enables. These improvements that emerge from strain induced modifications to the electronic band structure necessitate new ultra-sensitive tools for probing strain in semiconductors. Using electronic Raman scattering, we recently showed that it is possible to measure minute amounts of strain in thin semiconductor epilayers. We applied this strain measurement technique to two different semiconductor alloy systems, using coherently strained epitaxial thin films specifically designed to produce lattice-mismatch strains as small as 10-4. Comparing our strain sensitivity and signal strength in AlxGa1-xAs with those obtained using the industry-standard technique of phonon Raman scattering we found a sensitivity improvement of ×200, and a signal enhancement of 4 ×103 thus obviating key constraints in semiconductor strain metrology. The sensitivity of this approach rivals that of contemporary techniques and opens up a new realm for optically probing strain effects on electronic band structure. We acknowledge the financial support of the DOE Office of Science, BES under DE-AC36-80GO28308.

40 CFR 1065.145 - Gaseous and PM probes, transfer lines, and sampling system components.

Code of Federal Regulations, 2012 CFR

2012-07-01

... measuring sample flows by designing a passive sampling system that meets the following requirements: (A) The... number of bends, and have no filters. (B) If probes are designed such that they are sensitive to stack... design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw...

40 CFR 1065.145 - Gaseous and PM probes, transfer lines, and sampling system components.

Code of Federal Regulations, 2010 CFR

2010-07-01

... measuring sample flows by designing a passive sampling system that meets the following requirements: (A) The... number of bends, and have no filters. (B) If probes are designed such that they are sensitive to stack... design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw...

40 CFR 1065.145 - Gaseous and PM probes, transfer lines, and sampling system components.

Code of Federal Regulations, 2014 CFR

2014-07-01

... measuring sample flows by designing a passive sampling system that meets the following requirements: (A) The... number of bends, and have no filters. (B) If probes are designed such that they are sensitive to stack... design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw...

40 CFR 1065.145 - Gaseous and PM probes, transfer lines, and sampling system components.

Code of Federal Regulations, 2013 CFR

2013-07-01

... measuring sample flows by designing a passive sampling system that meets the following requirements: (A) The... number of bends, and have no filters. (B) If probes are designed such that they are sensitive to stack... design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw...

40 CFR 1065.145 - Gaseous and PM probes, transfer lines, and sampling system components.

Code of Federal Regulations, 2011 CFR

2011-07-01

... measuring sample flows by designing a passive sampling system that meets the following requirements: (A) The... number of bends, and have no filters. (B) If probes are designed such that they are sensitive to stack... design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw...

Using phylogenetic probes for quantification of stable isotope labeling and microbial community analysis

DOEpatents

Brodie, Eoin L; DeSantis, Todd Z; Karaoz, Ulas; Andersen, Gary L

2014-12-09

Herein is described methods for a high-sensitivity means to measure the incorporation of stable isotope labeled substrates into RNA following stable isotope probing experiments (SIP). RNA is hybridized to a set of probes such as phylogenetic microarrays and isotope incorporation is quantified such as by secondary ion mass spectrometer imaging (NanoSIMS).

Expanding probe repertoire and improving reproducibility in human genomic hybridization

PubMed Central

Dorman, Stephanie N.; Shirley, Ben C.; Knoll, Joan H. M.; Rogan, Peter K.

2013-01-01

Diagnostic DNA hybridization relies on probes composed of single copy (sc) genomic sequences. Sc sequences in probe design ensure high specificity and avoid cross-hybridization to other regions of the genome, which could lead to ambiguous results that are difficult to interpret. We examine how the distribution and composition of repetitive sequences in the genome affects sc probe performance. A divide and conquer algorithm was implemented to design sc probes. With this approach, sc probes can include divergent repetitive elements, which hybridize to unique genomic targets under higher stringency experimental conditions. Genome-wide custom probe sets were created for fluorescent in situ hybridization (FISH) and microarray genomic hybridization. The scFISH probes were developed for detection of copy number changes within small tumour suppressor genes and oncogenes. The microarrays demonstrated increased reproducibility by eliminating cross-hybridization to repetitive sequences adjacent to probe targets. The genome-wide microarrays exhibited lower median coefficients of variation (17.8%) for two HapMap family trios. The coefficients of variations of commercial probes within 300 nt of a repetitive element were 48.3% higher than the nearest custom probe. Furthermore, the custom microarray called a chromosome 15q11.2q13 deletion more consistently. This method for sc probe design increases probe coverage for FISH and lowers variability in genomic microarrays. PMID:23376933

Molecular Detection and Species-Specific Identification of Medically Important Aspergillus Species by Real-Time PCR in Experimental Invasive Pulmonary Aspergillosis ▿

PubMed Central

Walsh, Thomas J.; Wissel, Mark C.; Grantham, Kevin J.; Petraitiene, Ruta; Petraitis, Vidmantas; Kasai, Miki; Francesconi, Andrea; Cotton, Margaret P.; Hughes, Johanna E.; Greene, Lora; Bacher, John D.; Manna, Pradip; Salomoni, Martin; Kleiboeker, Steven B.; Reddy, Sushruth K.

2011-01-01

Diagnosis of invasive pulmonary aspergillosis (IPA) remains a major challenge to clinical microbiology laboratories. We developed rapid and sensitive quantitative PCR (qPCR) assays for genus- and species-specific identification of Aspergillus infections by use of TaqMan technology. In order to validate these assays and understand their potential diagnostic utility, we then performed a blinded study of bronchoalveolar lavage (BAL) fluid specimens from well-characterized models of IPA with the four medically important species. A set of real-time qPCR primers and probes was developed by utilizing unique ITS1 regions for genus- and species-specific detection of the four most common medically important Aspergillus species (Aspergillus fumigatus, A. flavus, A. niger, and A. terreus). Pan-Aspergillus and species-specific qPCRs with BAL fluid were more sensitive than culture for detection of IPA caused by A. fumigatus in untreated (P < 0.0007) and treated (P ≤ 0.008) animals, respectively. For infections caused by A. terreus and A. niger, culture and PCR amplification from BAL fluid yielded similar sensitivities for untreated and treated animals. Pan-Aspergillus PCR was more sensitive than culture for detection of A. flavus in treated animals (P = 0.002). BAL fluid pan-Aspergillus and species-specific PCRs were comparable in sensitivity to BAL fluid galactomannan (GM) assay. The copy numbers from the qPCR assays correlated with quantitative cultures to determine the pulmonary residual fungal burdens in lung tissue. Pan-Aspergillus and species-specific qPCR assays may improve the rapid and accurate identification of IPA in immunocompromised patients. PMID:21976757

Highly Sensitive Detection of Caspase-3/7 Activity in Living Mice Using Enzyme-Responsive 19F MRI Nanoprobes.

PubMed

Akazawa, Kazuki; Sugihara, Fuminori; Nakamura, Tatsuya; Mizukami, Shin; Kikuchi, Kazuya

2018-05-16

Highly sensitive imaging of enzymatic activities in the deep tissues of living mammals provides useful information about their biological functions and for developing new drugs; however, such imaging is challenging. 19 F magnetic resonance imaging (MRI) is suitable for noninvasive visualization of enzymatic activities without endogenous background signals. Although various enzyme-responsive 19 F MRI probes have been developed, most cannot be used for in vivo imaging because of their low sensitivity. Recently, we developed unique nanoparticles, called FLAMEs, that are composed of a liquid perfluorocarbon core and a robust silica shell, and demonstrated their outstanding sensitivity in vivo. Here, we report a highly functionalized nanoprobe, FLAME-DEVD 2, with an OFF/ON 19 F MRI switch for detecting caspase-3/7 activity based on the paramagnetic relaxation enhancement effect. To improve the cleavage efficiency of peptides by caspase-3, we designed a novel Gd 3+ complex-conjugated peptide, DEVD X ( X = 1, 2), which is a substrate peptide sequence tandemly repeated X times, and demonstrated that DEVD 2 showed faster cleavage kinetics than DEVD 1. By incorporating this novel concept into a signal activation strategy, FLAME-DEVD 2 showed a high 19 F MRI signal enhancement rate in response to caspase-3 activity. After intravenous injection of FLAME-DEVD 2 and an apoptosis-inducing reagent, caspase-3/7 activity in the spleen of a living mouse was successfully imaged by 19 F MRI. This imaging platform shows great potential for highly sensitive detection of enzymatic activities in vivo.

Characterizing the biocompatibility and tumor-imaging capability of Cu2S nanocrystals in vivo

NASA Astrophysics Data System (ADS)

Poulose, Aby Cheruvathoor; Veeranarayanan, Srivani; Mohamed, M. Sheikh; Sakamoto, Yasushi; Hirosawa, Narumi; Suzuki, Yuko; Zhang, Minfang; Yudasaka, Masako; Radhakrishnan, Neelima; Maekawa, Toru; Mohanan, P. V.; Sakthi Kumar, D.

2015-07-01

Multifunctional nanomaterial-based probes have had key impacts on high-resolution and high-sensitivity bioimaging and therapeutics. Typically, NIR-absorbing metal sulfide-based nanocrystals (NCs) are highly assuring due to their unique optical properties. Yet, their in vivo behavior remains undetermined, which in turn undermines their potential bioapplications. Herein, we have examined the application of PEGylated Cu2S NCs as tumor contrast optical nanoprobes as well as investigated the short- and long-term in vivo compatibility focusing on anti-oxidant defense mechanism, genetic material, immune system, and vital organs. The studies revealed an overall safe profile of the NCs with no apparent toxicity even at longer exposure periods. The acquired observations culminate into a set of primary safety data of this nanomaterial and the use of PEGylated Cu2S NCs as promising optical nanoprobes with immense futuristic bioapplications.

Hemozoin-generated vapor nanobubbles for transdermal reagent- and needle-free detection of malaria

PubMed Central

Lukianova-Hleb, Ekaterina Y.; Campbell, Kelly M.; Constantinou, Pamela E.; Braam, Janet; Olson, John S.; Ware, Russell E.; Sullivan, David J.; Lapotko, Dmitri O.

2014-01-01

Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called “hemozoin,” a unique component of all blood-stage malaria parasites, generates a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided transdermal noninvasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds, and can be realized as a compact, easy-to-use, inexpensive, and safe field technology. PMID:24379385

Hemozoin-generated vapor nanobubbles for transdermal reagent- and needle-free detection of malaria.

PubMed

Lukianova-Hleb, Ekaterina Y; Campbell, Kelly M; Constantinou, Pamela E; Braam, Janet; Olson, John S; Ware, Russell E; Sullivan, David J; Lapotko, Dmitri O

2014-01-21

Successful diagnosis, screening, and elimination of malaria critically depend on rapid and sensitive detection of this dangerous infection, preferably transdermally and without sophisticated reagents or blood drawing. Such diagnostic methods are not currently available. Here we show that the high optical absorbance and nanosize of endogenous heme nanoparticles called "hemozoin," a unique component of all blood-stage malaria parasites, generates a transient vapor nanobubble around hemozoin in response to a short and safe near-infrared picosecond laser pulse. The acoustic signals of these malaria-specific nanobubbles provided transdermal noninvasive and rapid detection of a malaria infection as low as 0.00034% in animals without using any reagents or drawing blood. These on-demand transient events have no analogs among current malaria markers and probes, can detect and screen malaria in seconds, and can be realized as a compact, easy-to-use, inexpensive, and safe field technology.

Magnetic nanomaterials and sensors for biological detection.

PubMed

Sobczak-Kupiec, Agnieszka; Venkatesan, Jayachandran; Alhathal AlAnezi, Adnan; Walczyk, Dorota; Farooqi, Ammad; Malina, Dagmara; Hosseini, Seyed Hossein; Tyliszczak, Bozena

2016-11-01

It is becoming progressively more understandable that sensitivity and versatility of magnetic biosensors provides unique platform for high performance diagnostics in clinical settings. Confluence of information suggested that magnetic biosensors required well-tailored magnetic particles as probes for detection that generate large and specific biological signal with minimum possible nonspecific binding. However, there are visible knowledge gaps in our understanding of the strategies to overcome existing challenges related to even smaller size of intracellular targets and lower signal-to-noise ratio than that in whole-cell studies, therefore tool designing and development for intracellular measurement and manipulation is problematic. In this review we describe magnetic nanoparticles, synthesis and sensing principles of magnetic nanoparticles as well as surface functionalization and modification and finally magnetic nanoparticles for medical diagnostics. This review gathers important and up-to-date information and may help to develop the method of obtaining magnetic materials especially for medical application. Copyright © 2016 Elsevier Inc. All rights reserved.

The dielectric signature of glass density

NASA Astrophysics Data System (ADS)

Rams-Baron, M.; Wojnarowska, Z.; Knapik-Kowalczuk, J.; Jurkiewicz, K.; Burian, A.; Wojtyniak, M.; Pionteck, J.; Jaworska, M.; Rodríguez-Tinoco, C.; Paluch, M.

2017-09-01

At present, we are witnessing a renewed interest in the properties of densified glasses prepared by isobaric cooling of a liquid at elevated pressure. As high-pressure densification emerges as a promising approach in the development of glasses with customized features, understanding and controlling their unique properties represent a contemporary scientific and technological goal. The results presented herein indicate that the applied high-pressure preparation route leads to a glassy state with higher density (˜1%) and a reduced free volume of about 7%. We show that these subtle structural changes remarkably influence the dielectric response and spectral features of β-relaxation in etoricoxib glass. Our study, combining dynamical and structural techniques, reveal that β-relaxation in etoricoxib is extremely sensitive to the variations in molecular packing and can be used to probe the changes in glass density. Such connection is technologically relevant and may advance further progress in the field.

Extreme sensitivity of graphene photoconductivity to environmental gases.

PubMed

Docherty, Callum J; Lin, Cheng-Te; Joyce, Hannah J; Nicholas, Robin J; Herz, Laura M; Li, Lain-Jong; Johnston, Michael B

2012-01-01

Graphene is a single layer of covalently bonded carbon atoms, which was discovered only 8 years ago and yet has already attracted intense research and commercial interest. Initial research focused on its remarkable electronic properties, such as the observation of massless Dirac fermions and the half-integer quantum Hall effect. Now graphene is finding application in touch-screen displays, as channels in high-frequency transistors and in graphene-based integrated circuits. The potential for using the unique properties of graphene in terahertz-frequency electronics is particularly exciting; however, initial experiments probing the terahertz-frequency response of graphene are only just emerging. Here we show that the photoconductivity of graphene at terahertz frequencies is dramatically altered by the adsorption of atmospheric gases, such as nitrogen and oxygen. Furthermore, we observe the signature of terahertz stimulated emission from gas-adsorbed graphene. Our findings highlight the importance of environmental conditions on the design and fabrication of high-speed, graphene-based devices.

Nanodiamond Landmarks for Subcellular Multimodal Optical and Electron Imaging

PubMed Central

Zurbuchen, Mark A.; Lake, Michael P.; Kohan, Sirus A.; Leung, Belinda; Bouchard, Louis-S.

2013-01-01

There is a growing need for biolabels that can be used in both optical and electron microscopies, are non-cytotoxic, and do not photobleach. Such biolabels could enable targeted nanoscale imaging of sub-cellular structures, and help to establish correlations between conjugation-delivered biomolecules and function. Here we demonstrate a sub-cellular multi-modal imaging methodology that enables localization of inert particulate probes, consisting of nanodiamonds having fluorescent nitrogen-vacancy centers. These are functionalized to target specific structures, and are observable by both optical and electron microscopies. Nanodiamonds targeted to the nuclear pore complex are rapidly localized in electron-microscopy diffraction mode to enable “zooming-in” to regions of interest for detailed structural investigations. Optical microscopies reveal nanodiamonds for in-vitro tracking or uptake-confirmation. The approach is general, works down to the single nanodiamond level, and can leverage the unique capabilities of nanodiamonds, such as biocompatibility, sensitive magnetometry, and gene and drug delivery. PMID:24036840

A neural circuit mechanism for regulating vocal variability during song learning in zebra finches.

PubMed

Garst-Orozco, Jonathan; Babadi, Baktash; Ölveczky, Bence P

2014-12-15

Motor skill learning is characterized by improved performance and reduced motor variability. The neural mechanisms that couple skill level and variability, however, are not known. The zebra finch, a songbird, presents a unique opportunity to address this question because production of learned song and induction of vocal variability are instantiated in distinct circuits that converge on a motor cortex analogue controlling vocal output. To probe the interplay between learning and variability, we made intracellular recordings from neurons in this area, characterizing how their inputs from the functionally distinct pathways change throughout song development. We found that inputs that drive stereotyped song-patterns are strengthened and pruned, while inputs that induce variability remain unchanged. A simple network model showed that strengthening and pruning of action-specific connections reduces the sensitivity of motor control circuits to variable input and neural 'noise'. This identifies a simple and general mechanism for learning-related regulation of motor variability.

3D-Printed Graphene/Polylactic Acid Electrodes Promise High Sensitivity in Electroanalysis.

PubMed

Manzanares Palenzuela, C Lorena; Novotný, Filip; Krupička, Petr; Sofer, Zdeněk; Pumera, Martin

2018-05-01

Additive manufacturing provides a unique tool for prototyping structures toward electrochemical sensing, due to its ability to produce highly versatile, tailored-shaped devices in a low-cost and fast way with minimized waste. Here we present 3D-printed graphene electrodes for electrochemical sensing. Ring- and disc-shaped electrodes were 3D-printed with a Fused Deposition Modeling printer and characterized using cyclic voltammetry and scanning electron microscopy. Different redox probes K 3 Fe(CN) 6 :K 4 Fe(CN) 6 , FeCl 3 , ascorbic acid, Ru(NH 3 ) 6 Cl 3 , and ferrocene monocarboxylic acid) were used to assess the electrochemical performance of these devices. Finally, the electrochemical detection of picric acid and ascorbic acid was carried out as proof-of-concept analytes for sensing applications. Such customizable platforms represent promising alternatives to conventional electrodes for a wide range of sensing applications.

Comparative advantages of mechanical biosensors.

PubMed

Arlett, J L; Myers, E B; Roukes, M L

2011-04-01

Mechanical interactions are fundamental to biology. Mechanical forces of chemical origin determine motility and adhesion on the cellular scale, and govern transport and affinity on the molecular scale. Biological sensing in the mechanical domain provides unique opportunities to measure forces, displacements and mass changes from cellular and subcellular processes. Nanomechanical systems are particularly well matched in size with molecular interactions, and provide a basis for biological probes with single-molecule sensitivity. Here we review micro- and nanoscale biosensors, with a particular focus on fast mechanical biosensing in fluid by mass- and force-based methods, and the challenges presented by non-specific interactions. We explain the general issues that will be critical to the success of any type of next-generation mechanical biosensor, such as the need to improve intrinsic device performance, fabrication reproducibility and system integration. We also discuss the need for a greater understanding of analyte-sensor interactions on the nanoscale and of stochastic processes in the sensing environment.

Closed-Loop Optogenetic Intervention in Mice

PubMed Central

Oijala, Mikko; Soltesz, Ivan

2014-01-01

Optogenetic interventions offer novel ways of probing, in a temporally specific manner, the roles of specific cell types in neuronal network functions of awake, behaving animals. Despite the unique potential for temporally specific optogenetic interventions in disease states, a major hurdle in its broad application to unpredictable brain states in a laboratory setting is constructing a real-time responsive system. We recently created a closed-loop system for stopping spontaneous seizures in chronically epileptic mice using optogenetic intervention. This system performs with very high sensitivity and specificity, and the strategy is relevant not only to epilepsy, but can also be used to react in real time, with optogenetic or other interventions, to diverse brain states. The protocol presented here is highly modular and requires variable time to perform. We describe the basic construction of a complete system, and include our downloadable custom closed-loop detection software which can be employed for this purpose. PMID:23845961

A new fluorescent probe for colorimetric and ratiometric detection of sulfur dioxide derivatives in liver cancer cells

NASA Astrophysics Data System (ADS)

Li, Dong-Peng; Wang, Zhao-Yang; Cui, Jie; Wang, Xin; Miao, Jun-Ying; Zhao, Bao-Xiang

2017-03-01

A new ratiometric fluorescent probe was constructed with hemicyanine and 7-nitrobenzofurazan for detection of sulfur dioxide derivatives (HSO3-/SO32-). The ratiometric response mode could be attributed to the efficient FRET (Förster resonance energy transfer) platform. The probe exbihited some desirable properties including fast response (within 2 minutes), good selectivity and high sensitivity. Moreover, the probe could detect endogenous HSO3- in liver cancer cells rather than normal liver cells, implying the diagnosal potential of the probe.

Results of the non-nulling calibration of five-hole pressure probe

NASA Astrophysics Data System (ADS)

Bereznai, J.; Mlynár, P.; Masaryk, M.

2017-09-01

In the laboratory of the Institute of Energy Machinery, Faculty of Mechanical Engineering in Bratislava were produced amount of pressure probes of different designs. Special position among themselves are five-hole pressure probe with tip of sphere or wedge used to determine the velocity vector in a unknown flow fields. Such probes have to be calibrated during blowing an air stream of known velocity magnitude and components of the velocity vector at different angles of attack, when the characteristic information about pressures on a sensitive part of the measuring probe is obtained.

Gravitational wave detection with the solar probe: I. Motivation

NASA Technical Reports Server (NTRS)

Thorne, K. S.

1978-01-01

Questions are posed and answered through discussion of gravitational wave detection with the Solar Probe. Discussed are: (1) what a gravitational wave is; (2) why wave detection is important; (3) what astrophysical information might be learned from these waves; (4) status of attempts to detect these waves; (5) why the Solar Probe is a special mission for detecting these waves; (6) how the Solar Probe's expected sensitivity compares with the strength of predicted gravitational waves; and (7) what gravity wave searchers will do after the Solar Probe.

Dual-Readout Immunochromatographic Assay by Utilizing MnO 2 Nanoflowers as the Unique Colorimetric/Chemiluminescent Probe

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

Ouyang, Hui; Lu, Qian; Wang, Wenwen

Manganese dioxide nanoflowers (MnO2 NFs) were synthesized and utilized as a dual readout probe to develop a novel immunochromatographic test strip (ITS) for detecting pesticide residues using chlorpyrifos as the model analyte. MnO2 NFs-labeled antibody for chlorpyrifos was employed as the signal tracer for conducting the ITS. After 10-min competitive immunoreaction, the tracer antibody was captured by the immobilized immunogen on test line in the test strip, resulting in the accumulation of MnO2 NFs. The accumulation of MnO2 NFs led to the appearance of brown color on the test line, which could be easily observed by the naked eye asmore » a qualitative readout. Moreover, MnO2 NFs showed a remarkably enhancing effect on the luminol-H2O2 chemiluminescent (CL) system. Unlike peroxidase-like nanomaterials, the enhancing mechanism of MnO2 NFs was based on its oxidant activity to decompose H2O2 for forming reactive oxygen species. After initiating the CL system in the test zone, strong CL signal was collected as a quantitative readout to sensitively detect chlorpyrifos. Under optimal conditions, the linear range of chlorpyrifos was 0.1–50 ng/mL with a low detection limit of 0.033 ng/mL (S/N = 3). The reliability of the dual-readout ITS was successfully demonstrated by the application on traditional Chinese medicine and environmental water samples. Due to the simultaneous rapid-qualitative and sensitive-quantitative detection, the dual-readout protocol provides a promising strategy for rapid screening and field assay on various areas such as environmental monitoring, food safety and point-of-care testing.« less

Spectroscopy of neutral and ionized PAHs. From laboratory studies to astronomical observations

NASA Technical Reports Server (NTRS)

Salama, Farid

2005-01-01

Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrochemistry is to reproduce (in a realistic way) the physical conditions that are associated with the emission and absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. PAHs, neutrals and ions, are expanded through a pulsed discharge nozzle (PDN) and probed with high-sensitivity cavity ringdown spectroscopy (CRDS). These laboratory experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase from the ultraviolet and visible range to the near-infrared range. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. Preliminary conclusions from the comparison of the laboratory data with astronomical observations of interstellar and circumstellar environments will also be discussed.

A molecular rotor based ratiometric sensor for basic amino acids.

PubMed

Pettiwala, Aafrin M; Singh, Prabhat K

2018-01-05

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Measurement of dentin hypersensitivity with the Jay Sensitivity Sensor Probe and the Yeaple probe to compare relief from dentin hypersensitivity by dentifrices.

PubMed

Kakar, Ashish; Kakar, Kanupriya

2013-05-01

To compare relief from dentin hypersensitivity (DH) after use of dentifrices formulated with potassium nitrate or fluoride. For the study, DH evaluations were conducted with the Jay Sensitivity Sensor Probe (Jay Probe), a novel tactile hypersensitivity instrument, in conjunction with three other DH methods, i.e. Yeaple probe (tactile), air blast, and the Visual Analog Scale (VAS). Adults (n = 100) who presented two teeth with DH and met study criteria were enrolled for this double-blind, randomized, parallel, controlled clinical trial conducted in an outpatient setting. DH evaluations at baseline were conducted by the tactile, air blast, and VAS methods. Subjects were randomly assigned a dentifrice formulated with 5% potassium nitrate and 1,000 ppm fluoride (as sodium monofluorophosphate) (Colgate Sensitive toothpaste; Test) or a commercially available fluoride dentifrice with 1,000 ppm fluoride as sodium monofluorophosphate (Colgate Cibaca toothpaste; Negative control). Subjects were recalled for DH evaluations after 4 and 8 weeks of product use. 85 subjects completed the entire study with evaluable results. Both treatments resulted in significant reductions in DH from baseline to all recall visits. In comparison to the Negative control, subjects in the Test group demonstrated significantly greater reductions for all DH evaluations at both 4 and 8 weeks (P < 0.05). Average tactile DH scores at week 8 for the Test and Negative control groups were 36.25 and 15.24 with the Yeaple probe and 35 and 12.43 with the Jay probe. Correspondingly, subjects in the Test group demonstrated significantly greater reductions in air blast and VAS responses for DH than those in the Negative control group (P < 0.05).

Free-stream static pressure measurements in the Longshot hypersonic wind tunnel and sensitivity analysis

NASA Astrophysics Data System (ADS)

Grossir, Guillaume; Van Hove, Bart; Paris, Sébastien; Rambaud, Patrick; Chazot, Olivier

2016-05-01

The performance of fast-response slender static pressure probes is evaluated in the short-duration, cold-gas, VKI Longshot hypersonic wind tunnel. Free-stream Mach numbers range between 9.5 and 12, and unit Reynolds numbers are within 3-10 × 106/m. Absolute pressure sensors are fitted within the probes, and an inexpensive calibration method, suited to low static pressure environments (200-1000 Pa), is described. Transfer functions relating the probe measurements p w to the free-stream static pressure p ∞ are established for the Longshot flow conditions based on numerical simulations. The pressure ratios p w / p ∞ are found to be close to unity for both laminar and turbulent boundary layers. Weak viscous effects characterized by small viscous interaction parameters {bar{χ }}<1.5 are confirmed experimentally for probe aspect ratios of L/ D > 16.5 by installing multiple pressure sensors in a single probe. The effect of pressure orifice geometry is also evaluated experimentally and found to be negligible for either straight or chamfered holes, 0.6-1 mm in diameter. No sensitivity to probe angle of attack could be evidenced for α < 0.33°. Pressure measurements are compared to theoretical predictions assuming an isentropic nozzle flow expansion. Significant deviations from this ideal case and the Mach 14 contoured nozzle design are uncovered. Validation of the static pressure measurements is obtained by comparing shock wave locations on Schlieren photographs to numerical predictions using free-stream properties derived from the static pressure probes. While these results apply to the Longshot wind tunnel, the present methodology and sensitivity analysis can guide similar investigations for other hypersonic test facilities.

Design and Application of Hybrid Magnetic Field-Eddy Current Probe

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Wallace, Terryl; Newman, Andy; Leser, Paul; Simpson, John

2013-01-01

The incorporation of magnetic field sensors into eddy current probes can result in novel probe designs with unique performance characteristics. One such example is a recently developed electromagnetic probe consisting of a two-channel magnetoresistive sensor with an embedded single-strand eddy current inducer. Magnetic flux leakage maps of ferrous materials are generated from the DC sensor response while high-resolution eddy current imaging is simultaneously performed at frequencies up to 5 megahertz. In this work the design and optimization of this probe will be presented, along with an application toward analysis of sensory materials with embedded ferromagnetic shape-memory alloy (FSMA) particles. The sensory material is designed to produce a paramagnetic to ferromagnetic transition in the FSMA particles under strain. Mapping of the stray magnetic field and eddy current response of the sample with the hybrid probe can thereby image locations in the structure which have experienced an overstrain condition. Numerical modeling of the probe response is performed with good agreement with experimental results.

The NASA Smart Probe Project for real-time multiple microsensor tissue recognition

NASA Technical Reports Server (NTRS)

Andrews, Russell J.; Mah, Robert W.

2003-01-01

BACKGROUND: Remote surgery requires automated sensors, effectors and sensor-effector communication. The NASA Smart Probe Project has focused on the sensor aspect. METHODS: The NASA Smart Probe uses neural networks and data from multiple microsensors for a unique tissue signature in real time. Animal and human trials use several probe configurations: (1) 8-microsensor probe (2.5 mm in diameter) for rodent studies (normal and subcutaneous mammary tumor tissues), and (2) 21-gauge needle probe with 3 spectroscopic fibers and an impedance microelectrode for breast cancer diagnosis in humans. Multisensor data are collected in real time (update 100 times/s) using PCs. RESULTS: Human data (collected by NASA licensee BioLuminate) from 15 women undergoing breast biopsy distinguished normal tissue from both benign tumors and breast carcinoma. Tumor margins and necrosis are rapidly detected. CONCLUSION: Real-time tissue identification is achievable. Potential applications, including probes incorporating nanoelectrode arrays, are presented. Copyright 2003 S. Karger AG, Basel.

Sensitive naked eye detection and quantification assay for nitrite by a fluorescence probe in various water resources

NASA Astrophysics Data System (ADS)

Zhang, Fengyuan; Zhu, Xinyue; Jiao, Zhijuan; Liu, Xiaoyan; Zhang, Haixia

2018-07-01

An uncontrolled increase of nitrite concentration in groundwater, rivers and lakes is a growing threat to public health and environment. It is important to monitor the nitrite levels in water and clinical diagnosis. Herein, we developed a switch-off fluorescence probe (PyI) for the sensitive detection of nitrite ions in the aqueous media. This probe selectively recognizes nitrite ions through a distinct visual color change from colorless to pink with a detection limit of 0.1 μM. This method has been successfully applied to the determination of nitrites in tap water, lake water and Yellow River water with recoveries in the range of 94.8%-105.4%.

Muon Spin Relaxation/Rotation Studies of Novel Magnetic Systems

NASA Astrophysics Data System (ADS)

Luke, Graeme

Muon spin relaxation/rotation is a powerful technique for probing magnetism in materials. As a real space probe, the muon complements neutron scattering's reciprocal space sensitivity. Muons probe magnetic fluctuations in a frequency window between inelastic neutron scattering and nuclear magnetic resonance. In this presentation I will describe our recent work on geometrically frustrated materials including the pyrochlore lattice compounds Yb2Ti

An Environmentally Sensitive Fluorescent Dye as a Multidimensional Probe of Amyloid Formation

PubMed Central

2016-01-01

We have explored amyloid formation using poly(amino acid) model systems in which differences in peptide secondary structure and hydrophobicity can be introduced in a controlled manner. We show that an environmentally sensitive fluorescent dye, dapoxyl, is able to identify β-sheet structure and hydrophobic surfaces, structural features likely to be related to toxicity, as a result of changes in its excitation and emission profiles and its relative quantum yield. These results show that dapoxyl is a multidimensional probe of the time dependence of amyloid aggregation, which provides information about the presence and nature of metastable aggregation intermediates that is inaccessible to the conventional probes that rely on changes in quantum yield alone. PMID:26865546

Nanowire lasers as intracellular probes.

PubMed

Wu, Xiaoqin; Chen, Qiushu; Xu, Peizhen; Chen, Yu-Cheng; Wu, Biming; Coleman, Rhima M; Tong, Limin; Fan, Xudong

2018-05-24

We investigate a cadmium sulfide (CdS) nanowire (NW) laser that is spontaneously internalized into a single cell to serve as a stand-alone intracellular probe. By pumping with nano-joule light pulses, green laser emission (500-520 nm) can be observed inside cells with a peak linewidth as narrow as 0.5 nm. Due to the sub-micron diameter (∼200 nm), the NW has an appreciable fraction of the evanescent field outside, facilitating a sensitive detection of cellular environmental changes. By monitoring the lasing peak wavelength shift in response to the intracellular refractive index change, our NW laser probe shows a sensitivity of 55 nm per RIU (refractive index units) and a figure of merit of approximately 98.

A transmission-grating-modulated pump-probe absorption spectroscopy and demonstration of diffusion dynamics of photoexcited carriers in bulk intrinsic GaAs film.

PubMed

Chen, Ke; Wang, Wenfang; Chen, Jianming; Wen, Jinhui; Lai, Tianshu

2012-02-13

A transmission-grating-modulated time-resolved pump-probe absorption spectroscopy is developed and formularized. The spectroscopy combines normal time-resolved pump-probe absorption spectroscopy with a binary transmission grating, is sensitive to the spatiotemporal evolution of photoinjected carriers, and has extensive applicability in the study of diffusion transport dynamics of photoinjected carriers. This spectroscopy has many advantages over reported optical methods to measure diffusion dynamics, such as simple experimental setup and operation, and high detection sensitivity. The measurement of diffusion dynamics is demonstrated on bulk intrinsic GaAs films. A carrier density dependence of carrier diffusion coefficient is obtained and agrees well with reported results.

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

Kim, M; Finlay, J; Zhu, T

Purpose: Photosensitizer concentration during photodynamic therapy (PDT) is an important parameter for accurate dosimetry. Fluorescence signal can be used as a measure of photosensitizer concentration. Two methods of data acquisition were compared to an ex vivo study both for in vivo and phantom models. Methods: Fluorescence signal of commonly used photosensitizer benzoporphyrin derivative monoacid ring A (BPD) was obtained in phantoms and mouse tumors using an excitation light of 405 nm. Interstitial fluorescence signal was obtained using a side-cut fiber inserted into the tumor tissue of interest. Using a previously developed multi-fiber probe, tumor surface fluorescence measurements were also collected.more » Signals were calibrated according to optical phantoms with known sensitizer fluorescence. Optical properties for each sample were determined and the influence of different absorption and scattering properties on the fluorescence signals was investigated. Using single value decomposition of the spectra, the sensitizer concentration was determined using the two different measurement geometries. An ex vivo analysis was also performed for tumor samples to determine the sensitizer concentration. Results: The two fluorescence signals obtained from the surface multi-fiber probe and the interstitial measurements were compared and were corresponding for both phantoms and mouse models. The values obtained were comparable to the ex vivo measurements as well. Despite the difference in geometry, the surface probe measurements can still be used as a metric for determining the presence of sensitizer in small volume tumors. Conclusion: The multi-fiber contact probe can be used as a tool to measure fluorescence at the surface of the treatment area for PDT and predict sensitizer concentration throughout the tumor. This is advantageous in that the measurement does not damage any tissue. Future work will include investigating the dependence of these results on intratumor sensitizer distribution.« less

Laser-based ultrasonics by dual-probe interferometer detection and narrow-band ultrasound generation

NASA Astrophysics Data System (ADS)

Huang, Jin

1993-01-01

Despite the advantages of laser-based ultrasonic (LBU) systems, the overall sensitivity of LBU systems needs to be improved for practical applications. Progress is reported to achieve better LBU detection accuracy and sensitivity for applications with surface waves and Lamb waves. A novel dual-probe laser interferometer has been developed to measure the same signal at two points. The dual-probe interferometer is a modification of a conventional single-probe interferometer in that the reference beam is guided to a second detecting point on the specimen surface to form a differential measurement mode, which measure the difference of the displacements at the two points. This dual-probe interferometer is particularly useful for accurate measurements of the speed and attenuation of surface waves and Lamb waves. The dual-probe interferometer has been applied to obtain accurate measurements of the surface wave speed and attenuation on surfaces of increasing surface roughness. It has also been demonstrated that with an appropriate signal processing method, namely, the power cepstrum method, the dual-probe interferometer is applicable to measure the local surface wave speed even when the probe separation is so small that the two waveforms in the interferometer output signal overlap in the time domain. Narrow-band signal generation and detection improve the sensitivity of LBU systems. It is proposed to use a diffraction grating to form an array of illuminating strips which form a source of narrowband surface and Lamb waves. The line-array of thermoelastic sources generates narrow-band signals whose frequency and bandwidth can be easily controlled. The optimum line-array parameters, such as width, spacing and the number of lines in the array have been derived theoretically and verified experimentally. Narrow-band signal generation with optimum parameters has been demonstrated. The enhanced LBU system with dual-probe detection and narrowband signal generation has been successfully applied to the detection of cracks emanating from rivet holes in aircraft fuselage panel samples. A compact fiber-optic dual-probe interferometer has also been developed and applied to the above mentioned problem of crack detection. Results agree well with those obtained with a bulk LBU system.

Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells.

PubMed

Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

2015-07-02

Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells. Copyright © 2015. Published by Elsevier B.V.

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

Karaulanov, Todor; Savukov, Igor; Kim, Young Jin

We constructed a spin-exchange relaxation-free (SERF) magnetometer with a small angle between the pump and probe beams facilitating a multi-channel design with a flat pancake cell. This configuration provides almost complete overlap of the beams in the cell, and prevents the pump beam from entering the probe detection channel. By coupling the lasers in multi-mode fibers, without an optical isolator or field modulation, we demonstrate a sensitivity of 10 fTmore » $$/\\sqrt{\\text{Hz}}$$ for frequencies between 10 Hz and 100 Hz. In addition to the experimental study of sensitivity, we present a theoretical analysis of SERF magnetometer response to magnetic fields for small-angle and parallel-beam configurations, and show that at optimal DC offset fields the magnetometer response is comparable to that in the orthogonal-beam configuration. Based on the analysis, we also derive fundamental and probe-limited sensitivities for the arbitrary non-orthogonal geometry. The expected practical and fundamental sensitivities are of the same order as those in the orthogonal geometry. As a result, we anticipate that our design will be useful for magnetoencephalography (MEG) and magnetocardiography (MCG) applications.« less

Noninvasive encapsulated fiber optic probes for interferometric measurement

NASA Astrophysics Data System (ADS)

Zboril, O.; Cubik, J.; Kepak, S.; Nedoma, J.; Fajkus, M.; Zavodny, P.; Vasinek, V.

2017-10-01

This article focuses on the sensitivity of encapsulated interferometric probes. These probes are used mainly for BioMed and security applications. Fiber-optic sensors are interesting for these applications, as they are resistant to electromagnetic interference (EMI) and that also do not affect the surrounding medical and security equipment. Using a loop of the optical fiber with is not a suitable for these measurements. The optical fiber should be fixed to one position, and should not significantly bend. For these reasons, the optical fiber is encapsulated. Furthermore, it is necessary that the encapsulated measuring probes were flexible, inert, water resistant and not toxic. Fiber-optic sensors shouldn't be magnetically active, so they can be used for example, in magnetic resonance environments (MR). Probes meeting these requirements can be widely used in health care and security applications. Encapsulation of interferometric measuring arm brings changes in susceptibility of measurements in comparison with the optical fiber without encapsulation. To evaluate the properties of the encapsulated probes, series of probes made from different materials for encapsulation was generated, using two types of optical fibers with various degrees of protection. Comparison of the sensitivity of different encapsulated probes was performed using a series of measurements at various frequencies. The measurement results are statistically compared in the article and commented. Given the desired properties polydimethylsiloxane (PDMS) polymer has been proven the most interesting encapsulating material for further research.

Eddy current probe response to open and closed surface flaws

NASA Technical Reports Server (NTRS)

Auld, B. A.; Muennemann, F.; Winslow, D. K.

1981-01-01

A general analysis of eddy current response to certain types of open and closed surface flaws is presented for both standard low-frequency and ferromagnetic-resonance (FMR) probes. It is shown analytically that for two-dimensional and three-dimensional surface flaws interrogated by a uniform probe field, the crack opening sensitivity increases with the operating frequency of the probe, this behavior being due to the Faraday induction effect. Experiments with low-frequency probes operating at or below 1 MHz and with the FMR probe operating at approximately 1000 MHz confirm this increase of the crack mouth opening displacement for practical situations where the probe field is not uniform in the vicinity of the flaw.

An excited-state intramolecular photon transfer fluorescence probe for localizable live cell imaging of cysteine

NASA Astrophysics Data System (ADS)

Liu, Wei; Chen, Wen; Liu, Si-Jia; Jiang, Jian-Hui

2017-03-01

Small molecule probes suitable for selective and specific fluorescence imaging of some important but low-concentration intracellular reactive sulfur species such as cysteine (Cys) pose a challenge in chemical biology. We present a readily available, fast-response fluorescence probe CHCQ-Ac, with 2-(5‧-chloro-2-hydroxyl-phenyl)-6-chloro-4(3 H)-quinazolinone (CHCQ) as the fluorophore and acrylate group as the functional moiety, that enables high-selectivity and high-sensitivity for detecting Cys in both solution and biological system. After specifically reacted with Cys, the probe undergoes a seven-membered intramolecular cyclization and released the fluorophore CHCQ with excited-state intramolecular photon transfer effect. A highly fluorescent, insoluble aggregate was then formed to facilitate high-sensitivity and high-resolution imaging. The results showed that probe CHCQ-Ac affords a remarkably large Stokes shift and can detect Cys under physiological pH condition with no interference from other analytes. Moreover, this probe was proved to have excellent chemical stability, low cytotoxicity and good cell permeability. Our design of this probe provides a novel potential tool to visualize and localize cysteine in bioimaging of live cells that would greatly help to explore various Cys-related physiological and pathological cellular processes in cell biology and diagnostics.

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

33S nuclear magnetic resonance spectroscopy of biological samples obtained with a laboratory model 33S cryogenic probe

NASA Astrophysics Data System (ADS)

Hobo, Fumio; Takahashi, Masato; Saito, Yuta; Sato, Naoki; Takao, Tomoaki; Koshiba, Seizo; Maeda, Hideaki

2010-05-01

S33 nuclear magnetic resonance (NMR) spectroscopy is limited by inherently low NMR sensitivity because of the quadrupolar moment and low gyromagnetic ratio of the S33 nucleus. We have developed a 10 mm S33 cryogenic NMR probe, which is operated at 9-26 K with a cold preamplifier and a cold rf switch operated at 60 K. The S33 NMR sensitivity of the cryogenic probe is as large as 9.8 times that of a conventional 5 mm broadband NMR probe. The S33 cryogenic probe was applied to biological samples such as human urine, bile, chondroitin sulfate, and scallop tissue. We demonstrated that the system can detect and determine sulfur compounds having SO42- anions and -SO3- groups using the S33 cryogenic probe, as the S33 nuclei in these groups are in highly symmetric environments. The NMR signals for other common sulfur compounds such as cysteine are still undetectable by the S33 cryogenic probe, as the S33 nuclei in these compounds are in asymmetric environments. If we shorten the rf pulse width or decrease the rf coil diameter, we should be able to detect the NMR signals for these compounds.

Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe.

PubMed

Fujii, T; Taguchi, Y; Saiki, T; Nagasaka, Y

2012-12-01

A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

36 CFR 261.9 - Property.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Damaging any plant that is classified as a threatened, endangered, sensitive, rare, or unique species. (d) Removing any plant that is classified as a threatened, endangered, sensitive, rare, or unique species. (e...

Hyperpolarized 15N-pyridine Derivatives as pH-Sensitive MRI Agents

PubMed Central

Jiang, Weina; Lumata, Lloyd; Chen, Wei; Zhang, Shanrong; Kovacs, Zoltan; Sherry, A. Dean; Khemtong, Chalermchai

2015-01-01

Highly sensitive MR imaging agents that can accurately and rapidly monitor changes in pH would have diagnostic and prognostic value for many diseases. Here, we report an investigation of hyperpolarized 15N-pyridine derivatives as ultrasensitive pH-sensitive imaging probes. These molecules are easily polarized to high levels using standard dynamic nuclear polarization (DNP) techniques and their 15N chemical shifts were found to be highly sensitive to pH. These probes displayed sharp 15N resonances and large differences in chemical shifts (Δδ >90 ppm) between their free base and protonated forms. These favorable features make these agents highly suitable candidates for the detection of small changes in tissue pH near physiological values. PMID:25774436

Probing new top physics at the LHCb experiment.

PubMed

Kagan, Alexander L; Kamenik, Jernej F; Perez, Gilad; Stone, Sheldon

2011-08-19

We suggest that top quark physics can be studied at the LHCb experiment and that top quark production could be observed. Since LHCb covers a large pseudorapidity region in the forward direction, it has unique abilities to probe new physics in the top quark sector. Furthermore, we demonstrate that LHCb may be able to measure a t ̄t production rate asymmetry and, thus, indirectly probe an anomalous forward-backward t ̄t asymmetry in the forward region, a possibility suggested by the enhanced forward-backward asymmetry reported by the CDF experiment. © 2011 American Physical Society

Improved Tumor Targeting and Longer Retention Time of NIR Fluorescent Probes Using Bioorthogonal Chemistry.

PubMed

Zhang, Xianghan; Wang, Bo; Zhao, Na; Tian, Zuhong; Dai, Yunpeng; Nie, Yongzhan; Tian, Jie; Wang, Zhongliang; Chen, Xiaoyuan

2017-01-01

The traditional labeling method for targeted NIR fluorescence probes requires directly covalent-bonded conjugation of targeting domains and fluorophores in vitro . Although this strategy works well, it is not sufficient for detecting or treating cancers in vivo , due to steric hindrance effects that relatively large fluorophore molecules exert on the configurations and physiological functions of specific targeting domains. The copper-free, "click-chemistry"-assisted assembly of small molecules in living systems may enhance tumor accumulation of fluorescence probes by improving the binding affinities of the targeting factors. Here, we employed a vascular homing peptide, GEBP11, as a targeting factor for gastric tumors, and we demonstrate its effectiveness for in vivo imaging via click-chemistry-mediated conjugation with fluorescence molecules in tumor xenograft mouse models. This strategy showed higher binding affinities than those of the traditional conjugation method, and our results showed that the tumor accumulation of click-chemistry-mediated probes are 11-fold higher than that of directly labeled probes. The tracking life was prolonged by 12-fold, and uptake of the probes into the kidney was reduced by 6.5-fold. For lesion tumors of different sizes, click-chemistry-mediated probes can achieve sufficient signal-to-background ratios (3.5-5) for in vivo detection, and with diagnostic sensitivity approximately 3.5 times that of traditional labeling probes. The click-chemistry-assisted detection strategy utilizes the advantages of "small molecule" probes while not perturbing their physiological functions; this enables tumor detection with high sensitivity and specific selectivity.

Photoswitchable non-fluorescent thermochromic dye-nanoparticle hybrid probes.

PubMed

Harrington, Walter N; Haji, Mwafaq R; Galanzha, Ekaterina I; Nedosekin, Dmitry A; Nima, Zeid A; Watanabe, Fumiya; Ghosh, Anindya; Biris, Alexandru S; Zharov, Vladimir P

2016-11-08

Photoswitchable fluorescent proteins with controllable light-dark states and spectral shifts in emission in response to light have led to breakthroughs in the study of cell biology. Nevertheless, conventional photoswitching is not applicable for weakly fluorescent proteins and requires UV light with low depth penetration in bio-tissue. Here we introduce a novel concept of photoswitchable hybrid probes consisting of thermochromic dye and absorbing nanoparticles, in which temperature-sensitive light-dark states and spectral shifts in absorption can be switched through controllable photothermal heating of doped nanoparticles. The proof-of-concept is demonstrated through the use of two different types of temperature-sensitive dyes doped with magnetic nanoparticles and reversibly photoswitched by a near-infrared laser. Photoacoustic imaging revealed the high contrast of these probes, which is sufficient for their visualization in cells and deep tissue. Our results suggest that these new photoswitchable multicolour probes can be used for multimodal cellular diagnostics and potentially for magnetic and photothermal therapy.

Photoswitchable non-fluorescent thermochromic dye-nanoparticle hybrid probes

NASA Astrophysics Data System (ADS)

Harrington, Walter N.; Haji, Mwafaq R.; Galanzha, Ekaterina I.; Nedosekin, Dmitry A.; Nima, Zeid A.; Watanabe, Fumiya; Ghosh, Anindya; Biris, Alexandru S.; Zharov, Vladimir P.

2016-11-01

Photoswitchable fluorescent proteins with controllable light-dark states and spectral shifts in emission in response to light have led to breakthroughs in the study of cell biology. Nevertheless, conventional photoswitching is not applicable for weakly fluorescent proteins and requires UV light with low depth penetration in bio-tissue. Here we introduce a novel concept of photoswitchable hybrid probes consisting of thermochromic dye and absorbing nanoparticles, in which temperature-sensitive light-dark states and spectral shifts in absorption can be switched through controllable photothermal heating of doped nanoparticles. The proof-of-concept is demonstrated through the use of two different types of temperature-sensitive dyes doped with magnetic nanoparticles and reversibly photoswitched by a near-infrared laser. Photoacoustic imaging revealed the high contrast of these probes, which is sufficient for their visualization in cells and deep tissue. Our results suggest that these new photoswitchable multicolour probes can be used for multimodal cellular diagnostics and potentially for magnetic and photothermal therapy.

Aminoquinoline based highly sensitive fluorescent sensor for lead(II) and aluminum(III) and its application in live cell imaging.

PubMed

Anand, Thangaraj; Sivaraman, Gandhi; Mahesh, Ayyavu; Chellappa, Duraisamy

2015-01-01

We have synthesized a new probe 5-((anthracen-9-ylmethylene) amino)quinolin-10-ol (ANQ) based on anthracene platform. The probe was tested for its sensing behavior toward heavy metal ions Hg(2+), Pb(2+), light metal Al(3+) ion, alkali, alkaline earth, and transition metal ions by UV-visible and fluorescent techniques in ACN/H2O mixture buffered with HEPES (pH 7.4). It shows high selectivity toward sensing Pb(2+)/Al(3+) metal ions. Importantly, 10-fold and 5- fold fluorescence enhancement at 429 nm was observed for probe upon complexation with Pb(2+) and Al(3+) ions, respectively. This fluorescence enhancement is attributable to the prevention of photoinduced electron transfer. The photonic studies indicate that the probe can be adopted as a sensitive fluorescent chemosensor for Pb(2+) and Al(3+) ions. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitive fluorescence detection of nucleic acids based on isothermal circular strand-displacement polymerization reaction.

PubMed

Guo, Qiuping; Yang, Xiaohai; Wang, Kemin; Tan, Weihong; Li, Wei; Tang, Hongxing; Li, Huimin

2009-02-01

Here we have developed a sensitive DNA amplified detection method based on isothermal strand-displacement polymerization reaction. This method takes advantage of both the hybridization property of DNA and the strand-displacement property of polymerase. Importantly, we demonstrate that our method produces a circular polymerization reaction activated by the target, which essentially allows it to self-detect. Functionally, this DNA system consists of a hairpin fluorescence probe, a short primer and polymerase. Upon recognition and hybridization with the target ssDNA, the stem of the hairpin probe is opened, after which the opened probe anneals with the primer and triggers the polymerization reaction. During this process of the polymerization reaction, a complementary DNA is synthesized and the hybridized target is displaced. Finally, the displaced target recognizes and hybridizes with another probe, triggering the next round of polymerization reaction, reaching a target detection limit of 6.4 x 10(-15) M.

DNA base pair resolution measurements using resonance energy transfer efficiency in lanthanide doped nanoparticles.

PubMed

Delplanque, Aleksandra; Wawrzynczyk, Dominika; Jaworski, Pawel; Matczyszyn, Katarzyna; Pawlik, Krzysztof; Buckle, Malcolm; Nyk, Marcin; Nogues, Claude; Samoc, Marek

2015-01-01

Lanthanide-doped nanoparticles are of considerable interest for biodetection and bioimaging techniques thanks to their unique chemical and optical properties. As a sensitive luminescence material, they can be used as (bio) probes in Förster Resonance Energy Transfer (FRET) where trivalent lanthanide ions (La3+) act as energy donors. In this paper we present an efficient method to transfer ultrasmall (ca. 8 nm) NaYF4 nanoparticles dispersed in organic solvent to an aqueous solution via oxidation of the oleic acid ligand. Nanoparticles were then functionalized with single strand DNA oligomers (ssDNA) by inducing covalent bonds between surface carboxylic groups and a 5' amine modified-ssDNA. Hybridization with the 5' fluorophore (Cy5) modified complementary ssDNA strand demonstrated the specificity of binding and allowed the fine control over the distance between Eu3+ ions doped nanoparticle and the fluorophore by varying the number of the dsDNA base pairs. First, our results confirmed nonradiative resonance energy transfer and demonstrate the dependence of its efficiency on the distance between the donor (Eu3+) and the acceptor (Cy5) with sensitivity at a nanometre scale.

A TaqMan-based real time PCR assay for specific detection and quantification of Xylella fastidiosa strains causing bacterial leaf scorch in oleander.

PubMed

Guan, Wei; Shao, Jonathan; Singh, Raghuwinder; Davis, Robert E; Zhao, Tingchang; Huang, Qi

2013-02-15

A TaqMan-based real-time PCR assay was developed for specific detection of strains of X. fastidiosa causing oleander leaf scorch. The assay uses primers WG-OLS-F1 and WG-OLS-R1 and the fluorescent probe WG-OLS-P1, designed based on unique sequences found only in the genome of oleander strain Ann1. The assay is specific, allowing detection of only oleander-infecting strains, not other strains of X. fastidiosa nor other plant-associated bacteria tested. The assay is also sensitive, with a detection limit of 10.4fg DNA of X. fastidiosa per reaction in vitro and in planta. The assay can also be applied to detect low numbers of X. fastidiosa in insect samples, or further developed into a multiplex real-time PCR assay to simultaneously detect and distinguish diverse strains of X. fastidiosa that may occupy the same hosts or insect vectors. Specific and sensitive detection and quantification of oleander strains of X. fastidiosa should be useful for disease diagnosis, epidemiological studies, management of oleander leaf scorch disease, and resistance screening for oleander shrubs. Published by Elsevier B.V.

Self-Assembled Core-Satellite Gold Nanoparticle Networks for Ultrasensitive Detection of Chiral Molecules by Recognition Tunneling Current.

PubMed

Zhang, Yuanchao; Liu, Jingquan; Li, Da; Dai, Xing; Yan, Fuhua; Conlan, Xavier A; Zhou, Ruhong; Barrow, Colin J; He, Jin; Wang, Xin; Yang, Wenrong

2016-05-24

Chirality sensing is a very challenging task. Here, we report a method for ultrasensitive detection of chiral molecule l/d-carnitine based on changes in the recognition tunneling current across self-assembled core-satellite gold nanoparticle (GNP) networks. The recognition tunneling technique has been demonstrated to work at the single molecule level where the binding between the reader molecules and the analytes in a nanojunction. This process was observed to generate a unique and sensitive change in tunneling current, which can be used to identify the analytes of interest. The molecular recognition mechanism between amino acid l-cysteine and l/d-carnitine has been studied with the aid of SERS. The different binding strength between homo- or heterochiral pairs can be effectively probed by the copper ion replacement fracture. The device resistance was measured before and after the sequential exposures to l/d-carnitine and copper ions. The normalized resistance change was found to be extremely sensitive to the chirality of carnitine molecule. The results suggested that a GNP networks device optimized for recognition tunneling was successfully built and that such a device can be used for ultrasensitive detection of chiral molecules.

Non-contact photoacoustic tomography and ultrasonography for brain imaging

NASA Astrophysics Data System (ADS)

Rousseau, Guy; Blouin, Alain; Monchalin, Jean-Pierre

2012-02-01

Photoacoustic tomography (PAT) and ultrasonography (US) of biological tissues usually rely on transducer arrays for the detection of ultrasound. Obtaining the best sensitivity requires a physical contact with the tissue using an intermediate coupling fluid (water or gel). This type of contact is a major drawback for several applications such as neurosurgery. Laser-ultrasonics is an established optical technique for the non-contact generation and detection of ultrasound in industrial materials. In this paper, the non-contact detection scheme used in laser-ultrasonics is adapted to allow probing of ultrasound in biological tissues while remaining below laser exposure safety limits. Both non-contact PAT (NCPAT) and non-contact US (NCUS) are demonstrated experimentally using a single-frequency detection laser emitting suitably shaped pulses and a confocal Fabry-Perot interferometer. It is shown that an acceptable sensitivity is obtained while remaining below the maximum permissible exposure (MPE) of biological tissues. Results obtained ex vivo with a calf brain specimen show that sub-mm endogenous and exogenous inclusions can be detected at depths exceeding 1 cm. When fully developed, the technique could be a unique diagnostic tool in neurosurgery providing deep imaging of blood vessels, blood clots and blood oxygenation.

Pristine carbon nanotubes based resistive temperature sensor

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

Alam, Md Bayazeed, E-mail: bayazeed786@gmail.com; Jamia Millia Islamia; Saini, Sudhir Kumar, E-mail: sudhirsaini1310@gmail.com

A good sensor must be highly sensitive, faster in response, of low cost cum easily producible, and highly reliable. Incorporation of nano-dimensional particles/ wires makes conventional sensors more effective in terms of fulfilling the above requirements. For example, Carbon Nanotubes (CNTs) are promising sensing element because of its large aspect ratio, unique electronic and thermal properties. In addition to their use for widely reported chemical sensing, it has also been explored for temperature sensing. This paper presents the fabrication of CNTs based temperature sensor, prepared on silicon substrate using low cost spray coating method, which is reliable and reproducible methodmore » to prepare uniform CNTs thin films on any substrate. Besides this, simple and inexpensive method of preparation of dispersion of single walled CNTs (SWNTs) in 1,2 dichlorobenzene by using probe type ultrasonicator for debundling the CNTs for improving sensor response were used. The electrical contacts over the dispersed SWNTs were taken using silver paste electrodes. Fabricated sensors clearly show immediate change in resistance as a response to change in temperature of SWNTs. The measured sensitivity (change in resistance with temperature) of the sensor was found ∼ 0.29%/°C in the 25°C to 60°C temperature range.« 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.

Sulfur dioxide in the atmosphere of Venus 1 sounding rocket observations

NASA Technical Reports Server (NTRS)

Mcclintock, William E.; Barth, Charles A.; Kohnert, Richard A.

1994-01-01

In this paper we present ultraviolet reflectance spectra obtained during two sounding rocket observations of Venus made during September 1988 and March 1991. We describe the sensitivity of the derived reflectance to instrument calibration and show that significant artifacts can appear in that spectrum as a result of using separate instruments to observe both the planetary radiance and the solar irradiance. We show that sulfur dioxide is the primary spectral absorber in the 190 - 230 nm region and that the range of altitudes probed by these wavelengths is very sensitive to incidence and emission angles. In a following paper Na et. al. (1994) show that sulfur monoxide features are also present in these data. Accurate identification and measurement of additional species require observations in which both the planetary radiance and the solar irradiance are measured with the same instrument. The instrument used for these observations is uniquely suited for obtaining large phase angle coverage and for studying transient atmospheric events on Venus because it can observe targets within 18 deg of the sun while earth orbiting instruments are restricted to solar elongation angles greater than or equal to 45 deg.

Investigation on Dynamic Calibration for an Optical-Fiber Solids Concentration Probe in Gas-Solid Two-Phase Flows

PubMed Central

Xu, Guiling; Liang, Cai; Chen, Xiaoping; Liu, Daoyin; Xu, Pan; Shen, Liu; Zhao, Changsui

2013-01-01

This paper presents a review and analysis of the research that has been carried out on dynamic calibration for optical-fiber solids concentration probes. An introduction to the optical-fiber solids concentration probe was given. Different calibration methods of optical-fiber solids concentration probes reported in the literature were reviewed. In addition, a reflection-type optical-fiber solids concentration probe was uniquely calibrated at nearly full range of the solids concentration from 0 to packed bed concentration. The effects of particle properties (particle size, sphericity and color) on the calibration results were comprehensively investigated. The results show that the output voltage has a tendency to increase with the decreasing particle size, and the effect of particle color on calibration result is more predominant than that of sphericity. PMID:23867745

Rare b-hadron decays as probe of new physics

NASA Astrophysics Data System (ADS)

Lanfranchi, Gaia

2018-05-01

The unexpected absence of unambiguous signals of New Physics (NP) at the TeV scale at the Large Hadron Collider (LHC) puts today flavor physics at the forefront. In particular, rare decays of b-hadrons represent a unique probe to challenge the Standard Model (SM) paradigm and test models of NP at a scale much higher than that accessible by direct searches. This article reviews the status of the field.

A low molecular weight artificial RNA of unique size with multiple probe target regions

NASA Technical Reports Server (NTRS)

Pitulle, C.; Dsouza, L.; Fox, G. E.

1997-01-01

Artificial RNAs (aRNAs) containing novel sequence segments embedded in a deletion mutant of Vibrio proteolyticus 5S rRNA have previously been shown to be expressed from a plasmid borne growth rate regulated promoter in E. coli. These aRNAs accumulate to high levels and their detection is a promising tool for studies in molecular microbial ecology and in environmental monitoring. Herein a new construct is described which illustrates the versatility of detection that is possible with aRNAs. This 3xPen aRNA construct carries a 72 nucleotide insert with three copies of a unique 17 base probe target sequence. This aRNA is 160 nucleotides in length and again accumulates to high levels in the E. coli cytoplasm without incorporating into ribosomes. The 3xPen aRNA illustrates two improvements in detection. First, by appropriate selection of insert size, we obtained an aRNA which provides a unique and hence, easily quantifiable peak, on a high resolution gel profile of low molecular weight RNAs. Second, the existence of multiple probe targets results in a nearly commensurate increase in signal when detection is by hybridization. These aRNAs are naturally amplified and carry sequence segments that are not found in known rRNA sequences. It thus may be possible to detect them directly. An experimental step involving RT-PCR or PCR amplification of the gene could therefore be avoided.

Studies on the formation and stability of triplex DNA using fluorescence correlation spectroscopy.

PubMed

Hu, Hongyan; Huang, Xiangyi; Ren, Jicun

2016-05-01

Triplex DNA has become one of the most useful recognition motifs in the design of new molecular biology tools, therapeutic agents and sophisticated DNA-based nanomaterials because of its direct recognition of natural double-stranded DNA. In this paper, we developed a sensitive and microscale method to study the formation and stability characterization of triplex DNA using fluorescence correlation spectroscopy (FCS). The principle of this method is mainly based on the excellent capacity of FCS for sensitively distinguishing between free single-strand DNA (ssDNA) fluorescent probes and fluorescent probe-double-strand DNA (dsDNA) hybridized complexes. First, we systematically investigated the experimental conditions of triplex DNA formation. Then, we evaluated the equilibrium association constants (K(a)) under different ssDNA probe lengths, composition and pH. Finally, we used FCS to measure the hybridization fraction of a 20-mer perfectly matched ssDNA probe and three single-base mismatched ssDNA probes with 146-mer dsDNA. Our data illustrated that FCS is a useful tool for the direct determination of the thermodynamic parameters of triplex DNA formation and discrimination of a single-base mismatch of triplex DNA without denaturation. Compared with current methods, our method is characterized by high sensitivity, good universality and small sample and reagent requirements. More importantly, our method has the potential to become a platform for triplex DNA research in vitro. Copyright © 2015 John Wiley & Sons, Ltd.

Bis-reaction-trigger as a strategy to improve the selectivity of fluorescent probes.

PubMed

Li, Dan; Cheng, Juan; Wang, Cheng-Kun; Ying, Huazhou; Hu, Yongzhou; Han, Feng; Li, Xin

2018-06-01

By the strategy of equipping a fluorophore with two reaction triggers that are tailored to the specific chemistry of peroxynitrite, we have developed a highly selective probe for detecting peroxynitrite in live cells. Sequential response by the two triggers enabled the probe to reveal various degrees of nitrosative stress in live cells via a sensitive emission colour change.

TOPICAL REVIEW: Probing the nuclear symmetry energy with heavy-ion collisions

NASA Astrophysics Data System (ADS)

Di Toro, M.; Baran, V.; Colonna, M.; Greco, V.

2010-08-01

Heavy ion collisions (HICs) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this review we present a selection of new reaction observables in dissipative collisions particularly sensitive to the symmetry term of the nuclear equation of state (Iso-EoS). We will first discuss the isospin equilibration dynamics. At low energies this manifests via the recently observed dynamical dipole radiation, due to a collective neutron-proton oscillation with the symmetry term acting as a restoring force. At higher beam energies Iso-EoS effects will be seen in an isospin diffusion mechanism, via imbalance ratio measurements, in particular from correlations to the total kinetic energy loss. For fragmentation reactions in central events we suggest to look at the coupling between isospin distillation and radial flow. In neck fragmentation reactions important Iso-EoS information can be obtained from the fragment isospin content, velocity and alignment correlations. The high-density symmetry term can be probed from isospin effects on heavy-ion reactions at relativistic energies (few A GeV range), in particular for high transverse momentum selections of the reaction products. Rather isospin sensitive observables are proposed from nucleon/cluster emissions, collective flows and meson production. The possibility of shedding light on the controversial neutron/proton effective mass splitting in asymmetric matter is also suggested. A large symmetry repulsion at high baryon density will also lead to an 'earlier' hadron-deconfinement transition in n-rich matter. The binodal transition line of the (T, ρB) diagram is lowered to a region accessible through heavy-ion collisions in the energy range of the new planned facilities, e.g. the FAIR/NICA projects. Some observable effects of the formation of a mixed phase are suggested, in particular a neutron trapping mechanism. The dependence of the results on a suitable treatment of the isovector part of the interaction in effective QCD Lagrangian approaches is critically discussed. We stress the interest of this study in nuclear astrophysics, in particular for supernovae explosions and neutron star structure, where the knowledge of the Iso-EoS is important at low as well as at high baryon density.

MnO2 nanosheet mediated "DD-A" FRET binary probes for sensitive detection of intracellular mRNA.

PubMed

Ou, Min; Huang, Jin; Yang, Xiaohai; Quan, Ke; Yang, Yanjing; Xie, Nuli; Wang, Kemin

2017-01-01

The donor donor-acceptor (DD-A) FRET model has proven to have a higher FRET efficiency than donor-acceptor acceptor (D-AA), donor-acceptor (D-A), and donor donor-acceptor acceptor (DD-AA) FRET models. The in-tube and in-cell experiments clearly demonstrate that the "DD-A" FRET binary probes can indeed increase the FRET efficiency and provide higher imaging contrast, which is about one order of magnitude higher than the ordinary "D-A" model. Furthermore, MnO 2 nanosheets were employed to deliver these probes into living cells for intracellular TK1 mRNA detection because they can adsorb ssDNA probes, penetrate across the cell membrane and be reduced to Mn 2+ ions by intracellular GSH. The results indicated that the MnO 2 nanosheet mediated "DD-A" FRET binary probes are capable of sensitive and selective sensing gene expression and chemical-stimuli changes in gene expression levels in cancer cells. We believe that the MnO 2 nanosheet mediated "DD-A" FRET binary probes have the potential as a simple but powerful tool for basic research and clinical diagnosis.

A sensitive plasmonic copper(II) sensor based on gold nanoparticles deposited on ITO glass substrate.

PubMed

Ding, Lijun; Gao, Yan; Di, Junwei

2016-09-15

Gold nanoparticles (Au NPs) based plasmonic probe was developed for sensitive and selective detection of Cu(2+) ion. The Au NPs were self-assembled on transparent indium tin oxide (ITO) film coated glass substrate using poly dimethyl diallyl ammonium chloride (PDDA) as a linker and then calcined at 400°C to obtain pure Au NPs on ITO surface (ITO/Au NPs). The probe was fabricated by functionalizing l-cysteine (Cys) on to gold surface (ITO/Au NPs/Cys). The strong chelation of Cu(2+) with Cys formed a stable Cys-Cu complex, and resulted in the red-shift of localized surface plasmon resonance (LSPR) peak of the Au NPs. The introduction of bovine serum albumin (BSA) as the second complexant could form complex of Cys-Cu-BAS and further markedly enhanced the red-shift of the LSPR peak. This plasmonic probe provided a highly sensitive and selective detection towards Cu(2+) ions, with a wide linear detection range (10(-11)-10(-5)M) over 6 orders of magnitude. The simple and cost-effective probe was successfully applied to the determination of Cu(2+) in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

A branch-migration based fluorescent probe for straightforward, sensitive and specific discrimination of DNA mutations

PubMed Central

Xiao, Xianjin; Wu, Tongbo; Xu, Lei; Chen, Wei

2017-01-01

Abstract Genetic mutations are important biomarkers for cancer diagnostics and surveillance. Preferably, the methods for mutation detection should be straightforward, highly specific and sensitive to low-level mutations within various sequence contexts, fast and applicable at room-temperature. Though some of the currently available methods have shown very encouraging results, their discrimination efficiency is still very low. Herein, we demonstrate a branch-migration based fluorescent probe (BM probe) which is able to identify the presence of known or unknown single-base variations at abundances down to 0.3%-1% within 5 min, even in highly GC-rich sequence regions. The discrimination factors between the perfect-match target and single-base mismatched target are determined to be 89–311 by measurement of their respective branch-migration products via polymerase elongation reactions. The BM probe not only enabled sensitive detection of two types of EGFR-associated point mutations located in GC-rich regions, but also successfully identified the BRAF V600E mutation in the serum from a thyroid cancer patient which could not be detected by the conventional sequencing method. The new method would be an ideal choice for high-throughput in vitro diagnostics and precise clinical treatment. PMID:28201758

A Novel SPM Probe with MOS Transistor and Nano Tip for Surface Electric Properties

NASA Astrophysics Data System (ADS)

Lee, Sang H.; Lim, Geunbae; Moon, Wonkyu

2007-03-01

In this paper, the novel SPM (Scanning Probe Microscope) probe with the planar MOS (Metal-Oxide-Semiconductor) transistor and the FIB (Focused Ion Beam) nano tip is fabricated for the surface electric properties. Since the MOS transistor has high working frequency, the device can overcome the speed limitation of EFM (Electrostatic Force Microscope) system. The sensitivity is also high, and no bulky device such as lock-in-amplifier is required. Moreover, the nano tip with nanometer scale tip radius is fabricated with FIB system, and the resolution can be improved. Therefore, the probe can rapidly detect small localized electric properties with high sensitivity and high resolution. The MOS transistor is fabricated with the common semiconductor process, and the nano tip is grown by the FIB system. The planar structure of the MOS transistor makes the fabrication process easier, which is the advantage on the commercial production. Various electric signals are applied using the function generator, and the measured data represent the well-established electric properties of the device. It shows the promising aspect of the local surface electric property detection with high sensitivity and high resolution.

Design and evaluation of a high sensitivity spiral TDR scour sensor

NASA Astrophysics Data System (ADS)

Gao, Quan; (Bill Yu, Xiong

2015-08-01

Bridge scour accounts for more than half of the reported bridge failures in the United States. Scour monitoring technology based on time domain reflectometry (TDR) features the advantages of being automatic and inexpensive. The senior author’s team has developed a few generations of a TDR bridge scour monitoring system, which have succeeded in both laboratory and field evaluations. In this study, an innovative spiral TDR sensor is proposed to further improve the sensitivity of the TDR sensor in scour detection. The spiral TDR sensor is made of a parallel copper wire waveguide wrapped around a mounting rod. By using a spiral path for the waveguide, the TDR sensor achieves higher sensitivity than the traditional straight TDR probes due to longer travel distance of the electromagnetic (EM) wave per unit length in the spiral probe versus traditional probe. The performance of the new TDR spiral scour sensor is validated by calibration with liquids with known dielectric constant and wet soils. Laboratory simulated scour-refilling experiments are performed to evaluate the performance of the new spiral probe in detecting the sediment-water interface and therefore the scour-refill process. The tests results indicate that scour depth variation of less than 2 cm can be easily detected by this new spiral sensor. A theory is developed based on the dielectric mixing model to simplify the TDR signal analyses for scour depth detection. The sediment layer thickness (directly related to scour depth) varies linearly with the square root of the bulk dielectric constant of the water-sediment mixture measured by the spiral TDR probe, which matches the results of theoretical prediction. The estimated sediment layer thickness and therefore scour depth from the spiral TDR sensor agrees very well with that by direct physical measurement. The spiral TDR sensor is four times more sensitive than a traditional straight TDR probe.

[Optimization and assessment of a reverse hybridization system for the detection of HBV drug-resistant mutations].

PubMed

Liu, Yan-chen; Huang, Ai-long; Hu, Yuan; Hu, Jie-li; Lai, Guo-qi; Zhang, Wen-lu

2011-12-01

To establish a detection method for HBV drug-resistant mutations related to lamivudine, adefovir and entecavir by optimization and assessment of reverse hybridization system. 26 degenerated probes covering 10 drug-resistant hotspots of 3 drugs were synthesized and immobilized on the same positively charged nylon membrane. PCR products labeled with digoxigenin were hybridized with corresponding probes. To improve the sensitivity and specificity, 4 reaction steps of reverse hybridization were optimized including the number of labeled digoxigenin, the energy intensity of UV cross-linking, hybridization and stringency wash conditions. To prove the feasibility, the specificity, sensitivity and accuracy of this system were assessed respectively. Sensitive and specific results are obtained by the optimization of the following 4 reaction steps: the primers labeled with 3 digoxigenin, energy intensity of UV cross-linking for 1500 x 0.1 mJ/cm², hybridization at 42 degrees C and stringency wash with 0.5 x SSC and 0.1% SDS solution at 44 degrees C for 30 min. In the assessment of system, the majority of probes have high specificity. The quantity of PCR product with a concentration of 10 ng/μl or above can be detected by this method. The concordant rate between reverse hybridization and direct sequencing is 93.9% in the clinical sample test. Though the specificity of several probes needs to be improved further, it is a simple, rapid and sensitive method which can detect HBV resistant mutations related to lamivudine, adefovir and entecavir simultaneously. Due to the short distance between 180 and 181, likewise 202 and 204, the sequence of the same probe covers two codon positions, and hybridization will be interfered by each other. To avoid such interference, the possible solution is that probes are designed by arranging and combining various forms of two near codons.

High sensitivity, loop-mediated isothermal amplification combined with colorimetric gold-nanoparticle probes for visual detection of high risk human papillomavirus genotypes 16 and 18.

PubMed

Kumvongpin, Ratchanida; Jearanaikool, Patcharee; Wilailuckana, Chotechana; Sae-Ung, Nattaya; Prasongdee, Prinya; Daduang, Sakda; Wongsena, Metee; Boonsiri, Patcharee; Kiatpathomchai, Wansika; Swangvaree, Sukumarn Sanersak; Sandee, Alisa; Daduang, Jureerut

2016-08-01

High-risk human papillomavirus (HR-HPV) causes cervical cancer. HPV16 and HPV18 are the most prevalent strains of the virus reported in women worldwide. Loop-mediated isothermal amplification (LAMP) is an alternative method for DNA detection under isothermal conditions. However, it results in a turbid amplified product which is not easily detected by the naked eye. This study aimed to develop an improved technique by using gold nanoparticles (AuNPs) attached to a single-stranded DNA probe for the detection of HPV16 and HPV18. Detection of the LAMP product by AuNP color change was compared with detection by visual turbidity. The optimal conditions for this new LAMP-AuNP assay were an incubation time of 20min and a temperature of 65°C. After LAMP amplification was complete, its products were hybridized with the AuNP probe for 5min and then detected by the addition of magnesium salt. The color changed from red to blue as a result of aggregation of the AuNP probe under high ionic strength conditions produced by the addition of the salt. The sensitivity of the LAMP-AuNP assay was greater than the LAMP turbidity assay by up to 10-fold for both HPV genotypes. The LAMP-AuNP assay showed higher sensitivity and ease of visualization than did the LAMP turbidity for the detection of HPV16 and HPV18. Additionally, AuNP-HPV16 and AuNP-HPV18 probes were stable for over 1year. The combination of LAMP and the AuNP-probe colorimetric assay offers a simple, rapid and highly sensitive alternative diagnostic tool for the detection of HPV16 and HPV18 in district hospitals or field studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Sensitive detection of T4 polynucleotide kinase activity based on multifunctional magnetic probes and polymerization nicking reactions mediated hyperbranched rolling circle amplification.

PubMed

Li, Xia; Xu, Xiaowen; Song, Juan; Xue, Qingwang; Li, Chenzhong; Jiang, Wei

2017-05-15

T4 polynucleotide kinase (PNK) plays critical roles in regulating DNA phosphorylation modes during the repair of DNA lesions. The aberrant activity of T4 PNK has been proven to be associated with a variety of human pathologies. Sensitive detection of T4 PNK activity is critical to both clinical diagnosis and therapeutics. Herein, a background-eliminated fluorescence assay for sensitive detection of T4 PNK activity has been developed by multifunctional magnetic probes and polymerization nicking reactions mediated hyperbranched rolling circle amplification (HRCA). First, the streptavidin-magnetic nanobeads (MBs) were functionalized with the biotin modified hairpin probe (HP) with 3'-phosphoryl, forming multifunctional magnetic probes (HP-MBs). Then, in the presence of T4 PNK, the 3'-phosphoryl of HP-MBs was hydrolyzed to 3'-hydroxyl, thus serving as primers to initiate the polymerization extension and nicking endonuclease cleavage reaction. Next, the primers released from above "polymerization-nicking" cycles were separated out to trigger the subsequently HRCA process, producing plenty of dsDNA. Finally, the intercalating dye SYBR Green I (SG) was inserted into the dsDNA, generating enhanced fluorescence signals. In our design, the HP-MBs here serve together as the T4 PNK, DNA polymerase, and endonuclease recognition probe, and thus avoid the demands of utilizing multiple probes design. Moreover, it performed primary "polymerization-nicking" amplification and mediate secondary HRCA. In addition to, performing the separation function, the binding of HP-MBs and SG could be avoided while a low background was acquired. This method showed excellent sensitivity with a detection limit of 0.0436 mU/mL, and accomplished exceptional characterization T4 PNK activity in cell extracts, offering a powerful tool for biomedical research and clinical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Noncontact diffuse correlation spectroscopy for noninvasive deep tissue blood flow measurement

NASA Astrophysics Data System (ADS)

Lin, Yu; He, Lian; Shang, Yu; Yu, Guoqiang

2012-01-01

A noncontact diffuse correlation spectroscopy (DCS) probe has been developed using two separated optical paths for the source and detector. This unique design avoids the interference between the source and detector and allows large source-detector separations for deep tissue blood flow measurements. The noncontact probe has been calibrated against a contact probe in a tissue-like phantom solution and human muscle tissues; flow changes concurrently measured by the two probes are highly correlated in both phantom (R2=0.89, p<10-5) and real-tissue (R2=0.77, p<10-5, n=9) tests. The noncontact DCS holds promise for measuring blood flow in vulnerable (e.g., pressure ulcer) and soft (e.g., breast) tissues without distorting tissue hemodynamic properties.

Dramatic Increase in the Signal and Sensitivity of Detection via Self-Assembly of Branched DNA

PubMed Central

Kim, Kyung-Tae; Chae, Chi-Bom

2011-01-01

In molecular testing using PCR, the target DNA is amplified via PCR and the sequence of interest is investigated via hybridization with short oligonucleotide capture probes that are either in a solution or immobilized on solid supports such as beads or glass slides. In this report, we report the discovery of assembly of DNA complex(es) between a capture probe and multiple strands of the PCR product. The DNA complex most likely has branched structure. The assembly of branched DNA was facilitated by the product of asymmetric PCR. The amount of branched DNA assembled was increased five fold when the asymmetric PCR product was denatured and hybridized with a capture probe all in the same PCR reaction mixture. The major branched DNA species appeared to contain three reverse strands (the strand complementary to the capture probe) and two forward strands. The DNA was sensitive to S1 nuclease suggesting that it had single-stranded gaps. Branched DNA also appeared to be assembled with the capture probes immobilized on the surface of solid support when the product of asymmetric PCR was hybridized. Assembly of the branched DNA was also increased when hybridization was performed in complete PCR reaction mixture suggesting the requirement of DNA synthesis. Integration of asymmetric PCR, heat denaturation and hybridization in the same PCR reaction mixture with the capture probes immobilized on the surface of solid support achieved dramatic increase in the signal and sensitivity of detection of DNA. Such a system should be advantageously applied for development of automated process for detection of DNA. PMID:21870112

Integrated signal probe based aptasensor for dual-analyte detection.

PubMed

Xiang, Juan; Pi, Xiaomei; Chen, Xiaoqing; Xiang, Lei; Yang, Minghui; Ren, Hao; Shen, Xiaojuan; Qi, Ning; Deng, Chunyan

2017-10-15

For the multi-analyte detection, although the sensitivity has commonly met the practical requirements, the reliability, reproducibility and stability need to be further improved. In this work, two different aptamer probes labeled with redox tags were used as signal probe1 (sP1) and signal probe2 (sP2), which were integrated into one unity DNA architecture to develop the integrated signal probe (ISP). Comparing with the conventional independent signal probes for the simultaneous multi-analyte detection, the proposed ISP was more reproducible and accurate. This can be due to that ISP in one DNA structure can ensure the completely same modification condition and an equal stoichiometric ratio between sP1 and sP2, and furthermore the cross interference between sP1 and sP2 can be successfully prevented by regulating the complementary position of sP1 and sP2. The ISP-based assay system would be a great progress for the dual-analyte detection. Combining with gold nanoparticles (AuNPs) signal amplification, the ISP/AuNPs-based aptasensor for the sensitive dual-analyte detection was explored. Based on DNA structural switching induced by targets binding to aptamer, the simultaneous dual-analyte detection was simply achieved by monitoring the electrochemical responses of methylene blue (MB) and ferrocene (Fc) This proposed detection system possesses such advantages as simplicity in design, easy operation, good reproducibility and accuracy, high sensitivity and selectivity, which indicates the excellent application of this aptasensor in the field of clinical diagnosis or other molecular sensors. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanometer scale thermometry in a living cell

PubMed Central

Kucsko, G.; Maurer, P. C.; Yao, N. Y.; Kubo, M.; Noh, H. J.; Lo, P. K.; Park, H.; Lukin, M. D.

2014-01-01

Sensitive probing of temperature variations on nanometer scales represents an outstanding challenge in many areas of modern science and technology1. In particular, a thermometer capable of sub-degree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool for many areas of biological, physical and chemical research; possibilities range from the temperature-induced control of gene expression2–5 and tumor metabolism6 to the cell-selective treatment of disease7,8 and the study of heat dissipation in integrated circuits1. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the sub-cellular level2–5. Here, we demonstrate a new approach to nanoscale thermometry that utilizes coherent manipulation of the electronic spin associated with nitrogen-vacancy (NV) color centers in diamond. We show the ability to detect temperature variations down to 1.8 mK (sensitivity of 9mK/Hz) in an ultra-pure bulk diamond sample. Using NV centers in diamond nanocrystals (nanodiamonds, NDs), we directly measure the local thermal environment at length scales down to 200 nm. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the sub-cellular level, enabling unique potential applications in life sciences. PMID:23903748

Flexible Graphene Transistor Architecture for Optical Sensor Technology

NASA Astrophysics Data System (ADS)

Ordonez, Richard Christopher

The unique electrical and optoelectronic properties of graphene allow tunable conductivity and broadband electromagnetic absorption that spans the ultraviolet and infrared regimes. However, in the current state-of-art graphene sensor architectures, junction resistance and doping concentration are predominant factors that affect signal strength and sensitivity. Unfortunately, graphene produces high contact resistances with standard electrode materials ( few kilo-ohms), therefore, signal is weak and large carrier concentrations are required to probe sensitivity. Moreover, the atomic thickness of graphene enables the potential for flexible electronics, but there has not been a successful graphene sensor architecture that demonstrates stable operation on flexible substrates and with minimal fabrication cost. In this study, the author explores a novel 3-terminal transistor architecture that integrates twodimensional graphene, liquid metal, and electrolytic gate dielectrics (LM-GFETs: Liquid Metal and Graphene Field-Effect Transistors ). The goal is to deliver a sensitive, flexible, and lightweight transistor architecture that will improve sensor technology and maneuverability. The reported high thermal conductivity of graphene provides potential for room-temperature thermal management without the need of thermal-electric and gas cooling systems that are standard in sensor platforms. Liquid metals provide a unique opportunity for conformal electrodes that maximize surface area contact, therefore, enable flexibility, lower contact resistance, and reduce damage to the graphene materials involved. Lastly, electrolytic gate dielectrics provide conformability and high capacitances needed for high on/off rations and electrostatic gating. Results demonstrated that with minimal fabrication steps the proposed flexible graphene transistor architecture demonstrated ambipolar current-voltage transfer characteristics that are comparable to the current state-of-the-art. An additional investigation demonstrated PN junction operation and the successful integration of the proposed architecture into an optoelectronic application with the use of semiconductor quantum dots in contact with the graphene material that acted as optical absorbers to increase detector gain. Applications that can benefit from such technology advancement include Nano-satellites (Nanosat), Underwater autonomous vehicles (UAV), and airborne platforms in which flexibility and sensitivity are critical parameters that must be optimized to increase mission duration and range.

Statistical analysis of an RNA titration series evaluates microarray precision and sensitivity on a whole-array basis

PubMed Central

Holloway, Andrew J; Oshlack, Alicia; Diyagama, Dileepa S; Bowtell, David DL; Smyth, Gordon K

2006-01-01

Background Concerns are often raised about the accuracy of microarray technologies and the degree of cross-platform agreement, but there are yet no methods which can unambiguously evaluate precision and sensitivity for these technologies on a whole-array basis. Results A methodology is described for evaluating the precision and sensitivity of whole-genome gene expression technologies such as microarrays. The method consists of an easy-to-construct titration series of RNA samples and an associated statistical analysis using non-linear regression. The method evaluates the precision and responsiveness of each microarray platform on a whole-array basis, i.e., using all the probes, without the need to match probes across platforms. An experiment is conducted to assess and compare four widely used microarray platforms. All four platforms are shown to have satisfactory precision but the commercial platforms are superior for resolving differential expression for genes at lower expression levels. The effective precision of the two-color platforms is improved by allowing for probe-specific dye-effects in the statistical model. The methodology is used to compare three data extraction algorithms for the Affymetrix platforms, demonstrating poor performance for the commonly used proprietary algorithm relative to the other algorithms. For probes which can be matched across platforms, the cross-platform variability is decomposed into within-platform and between-platform components, showing that platform disagreement is almost entirely systematic rather than due to measurement variability. Conclusion The results demonstrate good precision and sensitivity for all the platforms, but highlight the need for improved probe annotation. They quantify the extent to which cross-platform measures can be expected to be less accurate than within-platform comparisons for predicting disease progression or outcome. PMID:17118209

Xanthine oxidase functionalized Ta2O5 nanostructures as a novel scaffold for highly sensitive SPR based fiber optic xanthine sensor.

PubMed

Kant, Ravi; Tabassum, Rana; Gupta, Banshi D

2018-01-15

Fabrication and characterization of a surface plasmon resonance based fiber optic xanthine sensor using entrapment of xanthine oxidase (XO) enzyme in several nanostructures of tantalum (v) oxide (Ta 2 O 5 ) have been reported. Chemical route was adopted for synthesizing Ta 2 O 5 nanoparticles, nanorods, nanotubes and nanowires while Ta 2 O 5 nanofibers were prepared by electrospinning technique. The synthesized Ta 2 O 5 nanostructures were characterized by photoluminescence, scanning electron microscopy, UV-Visible spectra and X-ray diffraction pattern. The probes were fabricated by coating an unclad core of the fiber with silver layer followed by the deposition of XO entrapped Ta 2 O 5 nanostructures. The crux of sensing mechanism relies on the modification of dielectric function of sensing layer upon exposure to xanthine solution of diverse concentrations, reflected in terms of shift in resonance wavelength. The sensing probe coated with XO entrapped Ta 2 O 5 nanofibers has been turned out to possess maximum sensitivity amongst the synthesized nanostructures. The probe was optimized in terms of pH of the sample and the concentration of XO entrapped in Ta 2 O 5 nanofibers. The optimized sensing probe possesses a remarkably good sensitivity of 26.2nm/µM in addition to linear range from 0 to 3µM with an invincible LOD value of 0.0127µM together with a response time of 1min. Furthermore, probe selectivity with real sample analysis ensure the usage of the sensor for practical scenario. The results reported open a novel perspective towards a sensitive, rapid, reliable and selective detection of xanthine. Copyright © 2017 Elsevier B.V. All rights reserved.

High-sensitive electrochemical detection of point mutation based on polymerization-induced enzymatic amplification.

PubMed

Feng, Kejun; Zhao, Jingjin; Wu, Zai-Sheng; Jiang, Jianhui; Shen, Guoli; Yu, Ruqin

2011-03-15

Here a highly sensitive electrochemical method is described for the detection of point mutation in DNA. Polymerization extension reaction is applied to specifically initiate enzymatic electrochemical amplification to improve the sensitivity and enhance the performance of point mutation detection. In this work, 5'-thiolated DNA probe sequences complementary to the wild target DNA are assembled on the gold electrode. In the presence of wild target DNA, the probe is extended by DNA polymerase over the free segment of target as the template. After washing with NaOH solution, the target DNA is removed while the elongated probe sequence remains on the sensing surface. Via hybridizing to the designed biotin-labeled detection probe, the extended sequence is capable of capturing detection probe. After introducing streptavidin-conjugated alkaline phosphatase (SA-ALP), the specific binding between streptavidin and biotin mediates a catalytic reaction of ascorbic acid 2-phosphate (AA-P) substrate to produce a reducing agent ascorbic acid (AA). Then the silver ions in solution are reduced by AA, leading to the deposition of silver metal onto the electrode surface. The amount of deposited silver which is determined by the amount of wild target can be quantified by the linear sweep voltammetry (LSV). The present approach proved to be capable of detecting the wild target DNA down to a detection limit of 1.0×10(-14) M in a wide target concentration range and identifying -28 site (A to G) of the β-thalassemia gene, demonstrating that this scheme offers a highly sensitive and specific approach for point mutation detection. Copyright © 2010 Elsevier B.V. All rights reserved.

Novel DNA probes with low background and high hybridization-triggered fluorescence.

PubMed

Lukhtanov, Eugeny A; Lokhov, Sergey G; Gorn, Vladimir V; Podyminogin, Mikhail A; Mahoney, Walt

2007-01-01

Novel fluorogenic DNA probes are described. The probes (called Pleiades) have a minor groove binder (MGB) and a fluorophore at the 5'-end and a non-fluorescent quencher at the 3'-end of the DNA sequence. This configuration provides surprisingly low background and high hybridization-triggered fluorescence. Here, we comparatively study the performance of such probes, MGB-Eclipse probes, and molecular beacons. Unlike the other two probe formats, the Pleiades probes have low, temperature-independent background fluorescence and excellent signal-to-background ratios. The probes possess good mismatch discrimination ability and high rates of hybridization. Based on the analysis of fluorescence and absorption spectra we propose a mechanism of action for the Pleiades probes. First, hydrophobic interactions between the quencher and the MGB bring the ends of the probe and, therefore, the fluorophore and the quencher in close proximity. Second, the MGB interacts with the fluorophore and independent of the quencher is able to provide a modest (2-4-fold) quenching effect. Joint action of the MGB and the quencher is the basis for the unique quenching mechanism. The fluorescence is efficiently restored upon binding of the probe to target sequence due to a disruption in the MGB-quencher interaction and concealment of the MGB moiety inside the minor groove.

Novel DNA probes with low background and high hybridization-triggered fluorescence

PubMed Central

Lukhtanov, Eugeny A.; Lokhov, Sergey G.; Gorn, Vladimir V.; Podyminogin, Mikhail A.; Mahoney, Walt

2007-01-01

Novel fluorogenic DNA probes are described. The probes (called Pleiades) have a minor groove binder (MGB) and a fluorophore at the 5′-end and a non-fluorescent quencher at the 3′-end of the DNA sequence. This configuration provides surprisingly low background and high hybridization-triggered fluorescence. Here, we comparatively study the performance of such probes, MGB-Eclipse probes, and molecular beacons. Unlike the other two probe formats, the Pleiades probes have low, temperature-independent background fluorescence and excellent signal-to-background ratios. The probes possess good mismatch discrimination ability and high rates of hybridization. Based on the analysis of fluorescence and absorption spectra we propose a mechanism of action for the Pleiades probes. First, hydrophobic interactions between the quencher and the MGB bring the ends of the probe and, therefore, the fluorophore and the quencher in close proximity. Second, the MGB interacts with the fluorophore and independent of the quencher is able to provide a modest (2–4-fold) quenching effect. Joint action of the MGB and the quencher is the basis for the unique quenching mechanism. The fluorescence is efficiently restored upon binding of the probe to target sequence due to a disruption in the MGB–quencher interaction and concealment of the MGB moiety inside the minor groove. PMID:17259212

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.

Radiation Sensitization in Cancer Therapy.

ERIC Educational Resources Information Center

Greenstock, Clive L.

1981-01-01

Discusses various aspects of radiation damage to biological material, including free radical mechanisms, radiation sensitization and protection, tumor hypoxia, mechanism of hypoxic cell radiosensitization, redox model for radiation modification, sensitizer probes of cellular radiation targets, pulse radiolysis studies of free radical kinetics,…

Measuring Fluxes Of Heat To A Plasma-Arc Anode

NASA Technical Reports Server (NTRS)

Sankovic, John M.; Menart, James A.; Pfender, Emil; Heberlein, Joachim

1995-01-01

Three probes constructed to provide measurements indicative of conductive, convective, and radiative transfer of heat from free-burning plasma arc to water-cooled copper anode used in generating arc. Each probe consists mainly of copper body with two thermocouples embedded at locations 4 mm apart along length. Thermocouples provide measure of rate of conduction of heat along probe and transfers of heat from plasma to sensing surface at tip of probe. Probes identical except sensing surface of one uncoated and other two coated with different materials to make them sensitive to different components of overall flux of heat.

A novel dicyanoisophorone based red-emitting fluorescent probe with a large Stokes shift for detection of hydrazine in solution and living cells

NASA Astrophysics Data System (ADS)

Lv, Hongshui; Sun, Haiyan; Wang, Shoujuan; Kong, Fangong

2018-05-01

A novel dicyanoisophorone based fluorescent probe HP was developed to detect hydrazine. Upon the addition of hydrazine, probe HP displayed turn-on fluorescence in the red region with a large Stokes shift (180 nm). This probe exhibited high selectivity and high sensitivity to hydrazine in solution. The detection limit of HP was found to be 3.26 ppb, which was lower than the threshold limit value set by USEPA (10 ppb). Moreover, the probe was successfully applied to detect hydrazine in different water samples and living cells.

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

Fluorescent probes and nanoparticles for intracellular sensing of pH values

NASA Astrophysics Data System (ADS)

Shi, Wen; Li, Xiaohua; Ma, Huimin

2014-12-01

Intracellular pH regulates a number of cell metabolism processes and its sensing is thus of great importance for cell studies. Among various methods, fluorescent probes have been widely used for sensing intracellular pH values because of their high sensitivity and spatiotemporal resolution capability. In this article, the development of fluorescent probes with good practicability in sensing intracellular pH values and pH variation during 2009 - 2014 is reviewed. These fluorescence probes are divided into two kinds: small molecules and nanoparticles. Photophysical properties, advantages/disadvantages and applications of the two kinds of probes are discussed in detail.

Characterization of rpoB mutations in rifampin-resistant clinical Mycobacterium tuberculosis isolates from Kuwait and Dubai.

PubMed

Ahmad, Suhail; Mokaddas, Eiman; Fares, Esther

2002-11-01

Mutations conferring resistance to rifampin in rifampin-resistant clinical Mycobacterium tuberculosis isolates occur mostly in the 81 bp rifampin-resistance-determining region (RRDR) of the rpoB gene. In this study, 29 rifampin-resistant and 12 -susceptible clinical M. tuberculosis isolates were tested for characterization of mutations in the rpoB gene by line probe (INNO-LiPA Rif. TB) assay and the results were confirmed and extended by DNA sequencing of the PCR amplified target DNA. The line probe assay identified all 12 susceptible strains as rifampin-sensitive and the DNA sequence of RRDR in the amplified rpoB gene from two isolates matched perfectly with the wild-type sequence. The line probe assay identified 28 resistant isolates as rifampin-resistant with specific detection of mutation in 22 isolates including one isolate that exhibited hetro-resistance containing both the wild-type pattern as well as a specific mutation within RRDR while one of the rifampin-resistant strain was identified as rifampin-susceptible. DNA sequencing confirmed these results and, in addition, led to the specific detection of mutations in 5 rifampin-resistant isolates in which specific base changes within RRDR could not be determined by the line probe assay. These analyses identified 8 different mutations within RRDR of the rpoB gene including one novel mutation (S522W) that has not been reported so far. The genotyping performed on the isolates carrying similar mutations showed that majority of these isolates were unique as they exhibited varying DNA banding patterns. Correlating the ethnic origin of the infected TB patients with the occurrence of specific mutations at three main codon positions (516, 526 and 531) in the rpoB gene showed that most patients (11 of 15) from South Asian region contained mutations at codon 526 while majority of isolates from patients (6 of 11) of Middle Eastern origin contained mutations at codon 531.

Lab-on-fiber technology: a new vision for chemical and biological sensing.

PubMed

Ricciardi, Armando; Crescitelli, Alessio; Vaiano, Patrizio; Quero, Giuseppe; Consales, Marco; Pisco, Marco; Esposito, Emanuela; Cusano, Andrea

2015-12-21

The integration of microfluidics and photonic biosensors has allowed achievement of several laboratory functions in a single chip, leading to the development of photonic lab-on-a-chip technology. Although a lot of progress has been made to implement such sensors in small and easy-to-use systems, many applications such as point-of-care diagnostics and in vivo biosensing still require a sensor probe able to perform measurements at precise locations that are often hard to reach. The intrinsic property of optical fibers to conduct light to a remote location makes them an ideal platform to meet this demand. The motivation to combine the good performance of photonic biosensors on chips with the unique advantages of optical fibers has thus led to the development of the so-called lab-on-fiber technology. This emerging technology envisages the integration of functionalized materials on micro- and nano-scales (i.e. the labs) with optical fibers to realize miniaturized and advanced all-in-fiber probes, especially useful for (but not limited to) label-free chemical and biological applications. This review presents a broad overview of lab-on-fiber biosensors, with particular reference to lab-on-tip platforms, where the labs are integrated on the optical fiber facet. Light-matter interaction on the fiber tip is achieved through the integration of thin layers of nanoparticles or nanostructures supporting resonant modes, both plasmonic and photonic, highly sensitive to local modifications of the surrounding environment. According to the physical principle that is exploited, different configurations - such as localized plasmon resonance probes, surface enhanced Raman scattering probes and photonic probes - are classified, while various applications are presented in context throughout. For each device, the surface chemistry and the related functionalization protocols are reviewed. Moreover, the implementation strategies and fabrication processes, either based on bottom-up or top-down approaches, are discussed. In conclusion we highlight some of the further development opportunities, including lab-in-a-needle technology, which could have a direct and disruptive impact in localized cancer treatment applications.

NASA SMART Probe: Breast Cancer Application

NASA Technical Reports Server (NTRS)

Mah, Robert W.; Norvig, Peter (Technical Monitor)

2000-01-01

There is evidence in breast cancer and other malignancies that the physiologic environment within a tumor correlates with clinical outcome. We are developing a unique percutaneous Smart Probe to be used at the time of needle biopsy of the breast. The Smart Probe will simultaneously measure multiple physiologic parameters within a breast tumor. Direct and indirect measurements of tissue oxygen levels, blood flow, pH, and tissue fluid pressure will be analyzed in real-time. These parameters will be interpreted individually and collectively by innovative neural network techniques using advanced intelligent software. The goals are 1) develop a pecutaneous Smart Probe with multiple sensor modalities and applying advanced Information Technologies to provide real time diagnostic information of the tissue at tip of the probe, 2) test the percutaneous Smart Probe in women with benign and malignant breast masses who will be undergoing surgical biopsy, 3) correlate probe sensor data with benign and malignant status of breast masses, 4) determine whether the probe can detect physiologic differences within a breast tumor, and its margins, and in adjacent normal breast tissue, 5) correlate probe sensor data with known prognostic factors for breast caner, including tumor size, tumor grade, axillary lymph node metastases, estrogen receptor and progesterone receptor status.

Probing molecular dynamics in solution with x-ray valence-to-core spectroscopy

NASA Astrophysics Data System (ADS)

Doumy, Gilles; March, Anne Marie; Tu, Ming-Feng; Al Haddad, Andre; Southworth, Stephen; Young, Linda; Walko, Donald; Bostedt, Christoph

2017-04-01

Hard X-ray spectroscopies are powerful tools for probing the electronic and geometric structure of molecules in complex or disordered systems and have been particularly useful for studying molecules in the solution phase. They are element specific, sensitive to the electronic structure and the local arrangements of surrounding atoms of the element being selectively probed. When combined in a pump-probe scheme with ultrafast lasers, X-ray spectroscopies can be used to track the evolution of structural changes that occur after photoexcitation. Efficient use of hard x-ray radiation coming from high brilliance synchrotrons and upcoming high repetition rate X-ray Free Electron Lasers requires MHz repetition rate lasers and data acquisition systems. High information content Valence-to-Core x-ray emission is directly sensitive to the molecular orbitals involved in photochemistry. We report on recent progress towards fully enabling this photon-hungry technique for the study of time-resolved molecular dynamics, including efficient detection and use of polychromatic x-ray micro-probe at the Advanced Photon Source. Work was supported by the U.S. Department of Energy, Office of Science, Chemical Sciences, Geosciences, and Biosciences Division.

Quartz crystal microbalance (QCM) affinity biosensor for genetically modified organisms (GMOs) detection.

PubMed

Mannelli, Ilaria; Minunni, Maria; Tombelli, Sara; Mascini, Marco

2003-03-01

A DNA piezoelectric sensor has been developed for the detection of genetically modified organisms (GMOs). Single stranded DNA (ssDNA) probes were immobilised on the sensor surface of a quartz crystal microbalance (QCM) device and the hybridisation between the immobilised probe and the target complementary sequence in solution was monitored. The probe sequences were internal to the sequence of the 35S promoter (P) and Nos terminator (T), which are inserted sequences in the genome of GMOs regulating the transgene expression. Two different probe immobilisation procedures were applied: (a) a thiol-dextran procedure and (b) a thiol-derivatised probe and blocking thiol procedure. The system has been optimised using synthetic oligonucleotides, which were then applied to samples of plasmidic and genomic DNA isolated from the pBI121 plasmid, certified reference materials (CRM), and real samples amplified by the polymerase chain reaction (PCR). The analytical parameters of the sensor have been investigated (sensitivity, reproducibility, lifetime etc.). The results obtained showed that both immobilisation procedures enabled sensitive and specific detection of GMOs, providing a useful tool for screening analysis in food samples.

Feasibility of a wireless gamma probe in radioguided surgery.

PubMed

Park, Hye Min; Joo, Koan Sik

2016-06-21

Radioguided surgery through the use of a gamma probe is an established practice, and has been widely applied in the case of sentinel lymph node biopsies. A wide range of intraoperative gamma probes is commercially available. The primary characteristics of the gamma probes include their sensitivity, spatial resolution, and energy resolution. We present the results obtained from a prototype of a new wireless gamma probe. This prototype is composed of a 20 mm thick cerium-doped gadolinium aluminum gallium garnet (Ce:GAGG) inorganic scintillation crystal from Furukawa Denshi and a Hamamatsu S12572-100C multi-pixel photon counter equipped with a designed electronics. The measured performance characteristics include the energy resolution, energy linearity, angular aperture, spatial resolution and sensitivity. Measurements were carried out using (57)Co, (133)Ba, (22)Na, and (137)Cs sources. The energy resolutions for 0.122 and 0.511 MeV were 17.2% and 6.9%, respectively. The designed prototype consumes an energy of approximately 4.4 W, weighs about 310 g (including battery) having a dimension of 20 mm (D)  ×  130 mm (L).