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    31734 results match your criteria Analytical Chemistry [Journal]

    1 OF 635

    Native Electron Capture Dissociation Maps to Iron-Binding Channels in Horse Spleen Ferritin.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Native electron capture dissociation (NECD) is a process during which proteins undergo fragmentation similar to that from radical dissociation methods, but without the addition of exogenous electrons. However, after three initial reports of NECD from the cytochrome c dimer complex, no further evidence of the effect has been published. Here, we report NECD behavior from horse spleen ferritin, a ~490 kDa protein complex ~20-fold larger than the previously studied cytochrome c dimer. Read More

    High-precision simultaneous (18)O/(16)O, (13)C/(12)C and (17)O/(16)O analyses for µg-quantities of CaCO3 by tunable infrared laser absorption spectroscopy.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Stable isotope ratios ((18)O/(16)O, (13)C/(12)C and (17)O/(16)O) in carbonates have contributed greatly to understanding of Earth and planetary systems, climates, and history. Current methods for measuring isotopologues of CO2 derived from CaCO3 are primarily gas-source isotope ratio mass spectroscopy (IRMS). However, IRMS has drawbacks, such as mass overlap by multiple CO2 isotopologues and contaminants, the requirement of careful sample purification, and use of major instrumentation needing permanent installation and a high power electrical supply. Read More

    Multivariate Analysis of 2D (1)H,(13)C methyl NMR Spectra of Monoclonal Antibody Therapeutics to Facilitate Assessment of Higher Order Structure.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Two-dimensional (2D) 1H-13C methyl NMR provides a powerful tool to probe the higher order structure (HOS) of monoclonal antibodies (mAbs), since spectra can readily be acquired on intact mAbs at natural isotopic abundance, and small changes in chemical environment and structure give rise to observable changes in corresponding spectra, which can be interpreted at atomic resolution. This makes it possible to apply 2D NMR spectral fingerprinting approaches directly to drug products in order to systematically characterize structure and excipient effects. Systematic collections of NMR spectra are often analyzed in terms of the changes in specifically identified peak positions, as well as changes in peak height and linewidths. Read More

    A Facile and Sensitive Method for Protein Kinase A Activity Assay Based on Fluorescent Off-on PolyU-peptide Assembly.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Phosphorylation mediated by protein kinases plays a pivotal role in metabolic and cell-signaling processes, and the dysfunction of protein kinases such as protein kinase A (PKA) may induce several human diseases. Therefore it is of great significance to develop a facile and effective method for PKA activity assay and high-throughput screening of inhibitors. Herein, we develop a new fluorescent off-on method for PKA assay based on the assembly of anionic polyuridylic acid (polyU) and cationic fluorescent peptide. Read More

    J-Resolved 1H NMR 1D-Projections for Large-Scale Metabolic Phenotyping Studies: Application to Blood Plasma Analysis.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    1H nuclear magnetic resonance (NMR) spectroscopy-based metabolic phenotyping is now widely used for large-scale epidemiological applications. In order to minimize signal overlap present in 1D 1H NMR spectra, we have investigated the use of 2D J-resolved (JRES) 1H NMR spectroscopy for large-scale phenotyping studies. In particular, we have evaluated the use of the 1D projections of the 2D JRES spectra (pJRES), which provide single peaks for each of the J-coupled multiplets, using 706 human plasma samples from the FGENTCARD cohort. Read More

    Copper-Nitrogen Doped Graphene Hybrid as an Electrochemical Sensing Platform for Distinguishing DNA Bases.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    An electrochemical sensor using ultralight and porous copper-nitrogen doped graphene (CuNRGO) nanocomposite as the electrocatalyst has been constructed to simultaneously determine DNA bases such as guanine (G) and cytosine (C), adenine (A) and thymine (T). The nanocomposite is synthesized by thermally annealing an ice templated structure of graphene oxide (GO) and Cu(phen)2. Due to the unique structure and the presence of Cu(2+)-N active sites, the CuNRGO exhibits outstanding electrocatalytic activity toward the oxidation of free DNA bases. Read More

    A Microwave Flow Detector for Gradient Elution Liquid Chromatography.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    This study presents a microwave flow detector for liquid chromatography (LC) applications. The detector is based on a tunable microwave interferometer (MIM) with a vector network analyzer (VNA) for signal measurement and a computer for system control. A microstrip-line based flow cell with a volume of ~0. Read More

    A Quartz Crystal Microbalance Model for Quantitatively Probing the Deformation of Adsorbed Particles at Low Surface Coverage.
    Anal Chem 2017 Sep 21. Epub 2017 Sep 21.
    Characterizing the deformation of nanoscale, soft-matter particulates at solid-liquid interfaces is a demanding task, and there are limited experimental options to perform quantitative measurements in a non-perturbative manner. Previous attempts, based on the quartz crystal microbalance (QCM) technique, focused on the high surface coverage regime and modeled the adsorbed particles as a homogeneous film, while not considering the coupling between particles and surrounding fluid and hence resulting in an underestimation of the known particle height. In this work, we develop a model for the hydrodynamic coupling between adsorbed particles and surrounding fluid in the limit of a low surface coverage, which can be used to extract shape information from QCM measurement data. Read More

    Development of Visible-light Induced Photoelectrochemical Platform based on Cyclometalated Iridium(III) Complex for Bioanalysis.
    Anal Chem 2017 Sep 21. Epub 2017 Sep 21.
    The performance of the photoelectrochemical (PEC) bioanalysis relies closely on the properties of the usedphotoactive species. In this study, a visible-light induced PEC active species, [(C6)2Ir(dcbpy)]+PF6- (C6 = coumarin 6, dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid) was prepared based on C6 with the stronger absorbance in the visible region. The as-prepared complex was characterized by 1H NMR,UV-visible absorption and cyclic voltammetry. Read More

    Reduced Graphene Oxide-Based Solid-Phase Extraction for the Enrichment and Detection of microRNA.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Department of Biomedical Engineering, School of Medicine, Tsinghua University , Beijing 100084, China.
    MicroRNAs (miRNAs) are endogenous molecules with regulatory functions. The purification and enrichment of miRNA are essential for its precise and sensitive detection. miRNA isolated using commercial kits contains abundant interfering RNAs, and the concentration of miRNA may not be adequate for detection. Read More

    In situ characterization of Ni and Ni/Fe thin film electrodes for oxygen evolution in alkaline media by a Raman-coupled scanning electrochemical microscope setup.
    Anal Chem 2017 Sep 21. Epub 2017 Sep 21.
    We present a spectroelectrochemical setup, in which Raman microscopy is combined with scanning electrochemical microscopy (SECM) in order to provide both spectroscopic and electrochemical information of the very same location of an electrode at the same time. The setup is applied to a subject of high academic and practical interest, namely the oxygen evolution reaction at Ni and Ni/Fe electrodes. It comprises a transparent substrate electrode, onto which Ni and Ni/Fe thin films are deposited. Read More

    A Colorimetric Sensor Array Based on Gold Nanoparticles with Diverse Surface Charges for Microorganisms Identification.
    Anal Chem 2017 Sep 21. Epub 2017 Sep 21.
    We report a simple and novel colorimetric sensor array for rapid identification of microorganisms. In this study, four gold nanoparticles (AuNPs) with diverse surface charges were used as sensing elements. The interactions between AuNPs and microorganisms led to obvious color shifts, which could be observed by naked eyes. Read More

    Fluorescence Resonance Energy Transfer-Based DNA nanoprism with a Split Aptamer for ATP sensing in living cells.
    Anal Chem 2017 Sep 21. Epub 2017 Sep 21.
    We have developed a DNA nanoprobe for adenosine triphosphate (ATP) sensing in living cells, based on the split aptamer and the DNA triangular prism (TP). In which nucleic acid aptamer was split into two fragments, the stem of the split aptamer was respectively labeled donor and acceptor fluorophores that underwent an fluorescence resonance energy transfer if two ATP molecules were bound as target molecule to the recognition module. Hence, ATP as a target induced the self-assembly of split aptamer fragments and thereby brought the dual fluorophores into close proximity for high FRET efficiency. Read More

    Continuous sorting of cells based on differential P selectin glycoprotein ligand expression using molecular adhesion.
    Anal Chem 2017 Sep 20. Epub 2017 Sep 20.
    Cell surface molecular adhesions govern many important physiological processes and are used to identify cells for analysis and purifications. But most effective cell adhesion separation technologies use labels or long-term attachments in their application. While label-free separation microsystems typically separate cells by size, stiffness, and shape, they often do not provide sufficient specificity to cell type that can be obtained from molecular expression. Read More

    Ultra-Sensitive Quantitation of Plasma Membrane Proteins via isRTA.
    Anal Chem 2017 Sep 20. Epub 2017 Sep 20.
    Quantitation of plasma membrane proteins (PMPs) are fundamental and frequently performed in the daily lab-work. However, challenged by inherent/interacted hetero-structures and complex surroundings of the PMPs in lipid membrane, quantitative techniques for PMP often require complex treatments (e.g. Read More

    Probing Coordination Complexes by Carbon Nanotube-Assisted Low Voltage Paper Spray Ionization Mass Spectrometry.
    Anal Chem 2017 Sep 20. Epub 2017 Sep 20.
    Fragile transition metal complex ions such as [Cr(H2O)4Cl2]+, difficult to be observed by gas phase spectroscopy, are detected easily with carbon nanotube (CNT) assisted low voltage ambient ionization mass spectrometry. Observation of various substituted ions with D2O and ROH (R = CH3, C2H5…) established the versatility of the technique in detecting diverse species. Ligand substitution occurring in solution was captured by the low voltage technique. Read More

    Development of a Cigarette Tobacco Filler Standard Reference Material.
    Anal Chem 2017 Sep 20. Epub 2017 Sep 20.
    Centers for Disease Control and Prevention , Tobacco Products Laboratory, 4770 Buford Highway, Atlanta, Georgia 30341, United States.
    A new tobacco filler Standard Reference Material (SRM) has been issued by the National Institute of Standards and Technology (NIST) in September 2016 with certified and reference mass fraction values for nicotine, N-nitrosonornicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, and volatiles. The constituents have been determined by multiple analytical methods with measurements at NIST and at the Centers for Disease Control and Prevention, and with confirmatory measurements by commercial laboratories. This effort highlights the development of the first SRM for reduced nicotine and reduced tobacco-specific nitrosamines with certified values for composition. Read More

    Design of a Dual Channel Self-Reference Photoelectrochemical Biosensor.
    Anal Chem 2017 Sep 22. Epub 2017 Sep 22.
    Key Laboratory of Modern Agriculture Equipment and Technology, School of Chemistry and Chemical Engineering, Jiangsu University , Zhenjiang 212013, PR China.
    Photoelectrochemical (PEC) biosensors are usually based on the single photocurrent change caused by biorecognition events between analytes and probes. However, the photocurrent may be influenced by other factors besides target analytes and bring a false result. To improve the accuracy and reliability of PEC detection, here we proposed the design of a dual channel self-reference PEC biosensors. Read More

    Ultrasensitive Capture, Detection and Release of Circulating Tumor Cells Using Nanochannel-Ionchannel Hybrid Coupled with Electrochemical Detection Technique.
    Anal Chem 2017 Sep 20. Epub 2017 Sep 20.
    With the growing demands of the early, accurate, and sensitive diagnosis for cancers, the development of new diagnostic technologies becomes increasingly important. In this study, we proposed a strategy for efficient capture and sensitive detection of circulating tumor cells (CTCs) using array nanochannel-ionchannel hybrid coupled with electrochemical detection technique. The aptamer probe was immobilized on the ionchannel surface to couple with the protein overexpressed on CTCs membrane. Read More

    Medieval gilding technology of historical metal threads revealed by electron optical and micro-Raman spectroscopic study of focused ion beam-milled cross sections.
    Anal Chem 2017 Sep 19. Epub 2017 Sep 19.
    Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed cross-sectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano- and microscale textural, chemical and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron back-scattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy. Read More

    Chromatographic Properties of Minimal Aspect Ratio Monolithic Silica Columns.
    Anal Chem 2017 Sep 19. Epub 2017 Sep 19.
    We report on a study wherein we synthesized TMOS-based silica monolithic skeletons in capillaries with an i.d. of 5 and 10 μm to produce skeleton structures with very low capillary-to-domain size aspect-ratios. Read More

    Forensic Sampling and Analysis from a Single Substrate for Surface-Enhanced Raman Spectroscopy followed by Paper Spray Mass Spectrometry.
    Anal Chem 2017 Sep 19. Epub 2017 Sep 19.
    Sample preparation is the most common bottle-neck in the analysis and processing of forensic evidence. Time-consuming steps in many forensic tests involve complex separations such as liquid and gas chromatography or various types of extraction techniques, typically coupled with mass spectrometry (e.g. Read More

    Quantification of lignin and its structural features in plant biomass using (13)C lignin as internal standard for pyrolysis-GC-SIM-MS.
    Anal Chem 2017 Sep 19. Epub 2017 Sep 19.
    Understanding mechanisms underlying plant biomass recalcitrance at molecular level can only be achieved by accurate analyses of both content and structural features of the molecules involved. Current quantification of lignin is, however, majorly based on unspecific gravimetric analysis after sulphuric acid hydrolysis. Hence, our research aimed at specific lignin quantification with concurrent characterization of its structural features. Read More

    Fourier-transform MS and Closed-path Multi-reflection Time-of-Flight MS using an Electrostatic Linear Ion Trap.
    Anal Chem 2017 Sep 19. Epub 2017 Sep 19.
    An electrostatic linear ion trap (ELIT) has been configured to allow for the simultaneous acquisition of mass spectra via Fourier transform (FT) techniques (frequency measurement) and via time-of-flight (TOF) (time measurement). In the former case, the time-domain image charge derived from a pick-up electrode in the field-free region of the ELIT is converted to frequency-domain data via Fourier transformation (i.e. Read More

    AntDAS: Automatic Data Analysis Strategy for UPLC-QTOF-based Nontargeted Metabolic Profiling Analysis.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    High-quality data analysis methodology remains a bottleneck for metabolic profiling analysis based on ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The present work aims to address this problem by proposing a novel data analysis strategy wherein (1) chromatographic peaks in the UPLC-QTOF dataset are automatically extracted by using an advanced multiscale Gaussian smoothing-based peak extraction strategy. (2) A peak annotation stage is used to cluster fragment ions that belong to the same compound. Read More

    Cysteine-SILAC mass spectrometry enables the identification and quantitation of scrambled inter-chain disulfide bonds: preservation of native heavy-light chain pairing in bispecific IgGs generated by controlled Fab-arm exchange.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    Bispecific antibodies (bsAbs) are one of the most versatile and promising pharmaceutical innovations for countering heterogeneous and refractory disease by virtue of their ability to bind two distinct antigens. One critical quality attribute of bsAb formation requiring investigation is the potential randomization of cognate heavy chain (H)/light (L) chain pairing, which could occur to a varying extent dependent on bsAb format and the production platform. To assess the content of such HL chain-swapped reaction products with high sensitivity, we developed cysteine-SILAC, a method that facilitates the detailed characterization of disulfide-bridged peptides by mass-spectrometry. Read More

    Paper Sensor Coated with a Poly(carboxybetaine)-multiple DOPA Conjugate via Dip-coating for Biosensing in Complex Media.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    Cellulose paper is an ideal diagnostic platform for low-cost, easily disposable and lightweight implementation, but requires surface modification to achieve detection with high sensitivity and specificity in complex media. In this work, a polymer-catechol conjugate containing a super-hydrophilic nonfouling poly(carboxylbetaine) (pCB) and four surface-binding L-3,4-dihydroxyphenylalanine (DOPA) groups, pCB-(DOPA)4, were applied onto a paper-based sensor surface via a simple "graft-to" immersion process to render the surface with both nonfouling and protein functionalizable properties. This dip-coating technique is effective, convenient and robust as compared to the "graft-from" techniques reported previously with similar nonfouling properties. Read More

    Quantifying Secondary Structure Changes in Calmodulin using 2D-IR Spectroscopy.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    Revealing the details of biomolecular processes in solution needs tools that can monitor structural dynamics over a range of time and length scales. We assess the ability of 2D-IR spectroscopy in combination with multivariate data analysis to quantify changes in secondary structure of the multifunctional calcium-binding messenger protein Calmodulin (CaM) as a function of temperature and Ca2+ concentration. Our approach produced quantitative agreement with circular dichroism (CD) spectroscopy in detecting the domain melting transitions of Ca2+-free (apo) CaM (reduction in α-helix structure by 13% (CD) and 15% (2D)). Read More

    Tool for Rapid Analysis of glycopeptide by Permethylation (TRAP) via one-pot site mapping and glycan analysis.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    To overcome the challenges in the analysis of protein glycosylation, we have developed a comprehensive and universal tool through permethylation of glycopeptides and their tandem mass spectrometric analysis. This method has the potential to simplify glycoprotein analysis by integrating glycan sequencing and glycopeptide analysis in a single experiment. Moreover, glycans with unique glycosidic linkages, particularly from prokaryotes, which are resistant to enzymatic or chemical release, could also be detected and analyzed by this methodology. Read More

    Characterization of Site-Specific glycosylation in Influenza A Virus Hemagglutinin produced by Spodoptera frugiperda insect cell line.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    Influenza hemagglutinin is a surface glycoprotein related to virus invasion and host immune system response. Understanding site specific glycosylation of hemagglutinin will increase our knowledge about virus evolution and can improve the design and quality of vaccines. In our study, we used glycoproteomic analysis based on multienzyme digestion followed by LC tandem MS analysis to determine the glycosylation of Influenza hemagglutinin (H1/A/California/04/2009) using the following steps: PNGaseF treatment combined with trypsin or pepsin digestion were used to determine the glycosites and glycan occupancy. Read More

    Real-time metabolic interactions between two bacterial species using a carbon-based pH microsensor as a scanning electrochemical microscopy (SECM) probe.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    We have developed a carbon-based, fast-response potentiometric pH microsensor for use as a scanning electrochemical microscopy (SECM) chemical probe to quantitatively map the microbial metabolic exchange between two bacterial species, commensal Streptococcus gordonii and pathogenic Streptococcus mutans. The 25-μm diameter H+ ion-selective microelectrode or pH microprobe showed a Nernstian slope of 59 mV/pH and high selectivity against major ions such Na+, K+, Ca2+ and Mg2+. In addition, the unique conductive membrane composition aided us in performing an amperometric approach curve to position the probe and obtain a high-resolution pH map of the microenvironment produced by the lactate-producing S. Read More

    A far red emitting fluorescence probe for sensitive and selective detection of peroxynitrite in live cells and tissues.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    In this study, the far-red emitting fluorescence probe 1, containing a rhodamine derivative and a hydrazide reactive group, was developed for peroxynitrite detection and imaging. This probe, which is cell permeable and shows high sensitivity and selectivity in fluorometric detection of peroxynitrite over other ROS/RNS, was successfully utilized to detect exogenous and endogenous peroxynitrite in HeLa and RAW 264.7 cells, respectively. Read More

    Dual-activator codoped upconversion nanoprobe with core-multishell structure for in vitro and in vivo detection of hydroxyl radical.
    Anal Chem 2017 Sep 18. Epub 2017 Sep 18.
    Monitoring the fluctuation of hydroxyl radical (•OH) in the body can serve as an effective tool for the prediction of relative diseases, which, however, is highly challenging due to its short lifetime, high reactivity and extremely low concentration. Sandwich structured lanthanide-doped upconversion nanoparticles (UCNPs) exhibit unique luminescence properties and great prospects in bioimaging. Nonetheless, their rather low luminescence efficiency and intensity are serious limitations for their application. Read More

    Optimization of the determination method for dissolved cyanobacterial toxin BMAA in natural water.
    Anal Chem 2017 Sep 17. Epub 2017 Sep 17.
    There is a serious dispute on the existence of β-N-methylamino-L-alanine (BMAA) in water, which is a neurotoxin that may cause Amyotrophic lateral sclerosis/Parkinson's disease (ALS/PDC) and Alzheimer' disease. It is believed that a reliable and sensitive analytical method for the determination of BMAA is urgently required to resolve this dispute. In the present study, the solid phase extraction (SPE) procedure and the analytical method for dissolved BMAA in water were investigated and optimized. Read More

    Systems-Level Annotation of a Metabolomics Data Set Reduces 25 000 Features to Fewer than 1000 Unique Metabolites.
    Anal Chem 2017 Sep 15. Epub 2017 Sep 15.
    Department of Chemistry, Washington University , St. Louis, Missouri 63130, United States.
    When using liquid chromatography/mass spectrometry (LC/MS) to perform untargeted metabolomics, it is now routine to detect tens of thousands of features from biological samples. Poor understanding of the data, however, has complicated interpretation and masked the number of unique metabolites actually being measured in an experiment. Here we place an upper bound on the number of unique metabolites detected in Escherichia coli samples analyzed with one untargeted metabolomics method. Read More

    A fluorescence assay for ribonuclease H based on non-labeled substrate and DNAzyme assisted cascade amplification.
    Anal Chem 2017 Sep 15. Epub 2017 Sep 15.
    As a highly conserved damage repair protein, RNase H can specifically hydrolyze RNA in DNA-RNA chimeric strands. DNAzyme, a synthetic single-stranded DNA consisting of binding and catalytic sites, can cleave RNA in the presence of cofactors. In this study, we establish a highly sensitive RNase H assay assisted with DNAzyme's cleavage property. Read More

    Direct Sampling and Analysis of Atmospheric Particulate Organic Matter by Proton-Transfer-Reaction Mass Spectrometry.
    Anal Chem 2017 Sep 15. Epub 2017 Sep 15.
    We report on a new method for analyzing atmospheric submicrometer particulate organic matter which combines direct particle sampling and volatilization with on-line chemical ionization mass spectrometric analysis. Technically, the method relies on the combined use of a CHARON ("Chemical Analysis of Aerosol On-line") particle inlet and a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS). Laboratory studies on target analytes showed that the ionization conditions in the PTR-ToF-MS lead to extensive fragmentation of levoglucosan and cis-pinonic acid, while protonated oleic acid and 5-cholestane molecules remain intact. Read More

    A Ratiometric Fluorescent Probe for Imaging of Pantetheinase in Living Cells.
    Anal Chem 2017 Sep 15. Epub 2017 Sep 15.
    Pantetheinase, which catalyzes the cleavage of pantetheine to pantothenic acid (vitamin B5) and cysteamine, is involved in the regulation of oxidative stress, pantothenate recycling and cell migration. However, further elucidating the cellular function of this enzyme is largely limited by the lack of a suitable fluorescence imaging probe. By conjugating pantothenic acid with cresyl violet, herein we develop a new fluorescence probe CV-PA for the assay of pantetheinase. Read More

    Fast and simple protocols for mass spectrometry-based proteomics of small fresh frozen uterine tissue sections.
    Anal Chem 2017 Sep 14. Epub 2017 Sep 14.
    Human tissues are an important link between organ specific spatial molecular information, patient pathology and patient treatment options. However, patient tissues are uniquely obtained by time and location, and limited in their availability and size. Currently little knowledge exists about appropriate and simplified protocols for routine MS-based analysis of the various types and sizes of tissues. Read More

    Macromolecular profiling of organelles in normal diploid and cancer cells.
    Anal Chem 2017 Sep 14. Epub 2017 Sep 14.
    To advance an understanding of cellular regulation and function it is crucial to identify molecular contents in cellular organelles, which accommodate specific biochemical processes. Towards achievement of this goal, we applied micro-Raman-Biomolecular Component Analysis assay for molecular profiling of major organelles in live cells. We used this assay for comparative analysis of proteins 3D conformation and quantification of proteins, RNA and lipids concentrations in nucleoli, endoplasmic reticulum and mitochondria of WI-38 diploid lung fibroblasts and HeLa cancer cells. Read More

    Open-source Assisted Laboratory Automation through Graphical User Interfaces and 3D Printers. Application to Equipment Hyphenation for Higher-order data Generation.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    In the current analytical chemistry, even though the modeling of higher-order data can result attractive, the generation of this kind of data implies some automation challenges, which are mainly related to the hidden programming languages and electronic details of the equipment. When techniques and/or equipment hyphenation is the key to obtain higher-order data, the required simultaneous control of them demands funds for new hardware, software and licenses, and also really skilled operators. In this work we present Design of Inputs-Outputs with Sikuli (D. Read More

    Improvement of LOD in Fluorescence Detection with Spectrally Non-Uniform Background by Optimization of Emission Filtering.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    The limit-of-detection (LOD) in analytical instruments with fluorescence detection can be improved by reducing noise of optical background. Efficiently reducing optical background noise in systems with spectrally non-uniform background requires complex optimization of an emission filter - the main element of spectral filtration. Here we introduce a filter-optimization method which utilizes an expression for the signal-to-noise ratio (SNR) as a function of (i) all noise components (dark, shot, and flicker), (ii) emission spectrum of the analyte, (iii) emission spectrum of the optical background, and (iv) transmittance spectrum of the emission filter. Read More

    Non-invasive synchrotron-based X-Ray Raman scattering discriminates carbonaceous compounds in ancient and historical materials.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 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. Read More

    Time-resolved fluorescence immunochromatographic assay developed using two idiotypic nanobodies for rapid, quantitative, and simultaneous detection of aflatoxin and zearalenone in maize and its products.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    Aflatoxins and zearalenone (ZEN) are highly common mycotoxins in maize and maize-based products. This study aimed to report a time-resolved fluorescence immunochromatographic assay (TRFICA) developed using two idiotypic nanobodies for rapid, quantitative, and simultaneous detection of aflatoxin B1 (AFB1) and ZEN in maize and its products. A novel Eu/Tb(III) nanosphere with enhanced fluorescence was prepared as a label and conjugated to anti-idiotypic nanobody (AIdnb) and monoclonal antibody (mAb). Read More

    Glycoforest 1.0.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    Tandem mass spectrometry, when combined with liquid chromatography and applied to complex mixtures produces large amounts of raw data, which needs to be analysed to identify molecular structures. This technique is widely used, particularly in glycomics. Due to a lack of high throughput glycan sequencing software, glycan spectra are predominantly sequenced manually. Read More

    Determination of The 13C/12C Carbon Isotope Ratio in Carbonates and Bicarbonates by 13C NMR Spectroscopy.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    This paper is the first study focused on the innovative application of 13C NMR (Nuclear Magnetic Resonance) spectroscopy to determine the bulk 13C/12C carbon isotope ratio, at natural abundance, in inorganic carbonates and bicarbonates. In the past, 13C NMR spectroscopy (irm-13C NMR) was mainly used to measure isotope ratio monitoring with the potential of conducting 13C position-specific isotope analysis of organic molecules with high precision. The reliability of the newly developed methodology for the determination of stable carbon isotope ratio was evaluated in comparison with the method chosen in the past for these measurements, i. Read More

    Peptide-level interactions between proteins and small-molecule drug candidates by HDX-MS, PLIMSTEX and modified SUPREX: the example of ApoE3.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    We describe a platform utilizing two methods based on hydrogen-deuterium exchange (HDX) coupled with mass spectrometry (MS) to characterize interactions between a protein and a small-molecule ligand. The model system is apolipoprotein E3 (apoE3) and a small-molecule drug candidate. We extended PLIMSTEX (protein-ligand interactions by mass spectrometry, titration, and H/D Exchange) to the regional level by incorporating enzymatic digestion to acquire binding information for peptides. Read More

    Correlative Microscopy combining Secondary Ion Mass Spectrometry and Electron Microscopy: Comparison of Intensity-Hue-Saturation and Laplace Pyramid Methods for Image Fusion.
    Anal Chem 2017 Sep 13. Epub 2017 Sep 13.
    Correlative microscopy combining various imaging modalities offers powerful insights to obtain a comprehensive understanding of physical, chemical and biological phenomena. In this article, we investigate two approaches for image-fusion in the context of combining the inherently lower-resolution chemical images obtained using Secondary Ion Mass Spectrometry (SIMS) with the high-resolution ultrastructural images obtained using Electron Microscopy (EM). We evaluate the image fusion methods with three different case-studies selected to broadly represent the typical samples in life science research: (i) histology (unlabeled tissue), (ii) nanotoxicology, and (iii) metabolism (isotopically labelled tissue). Read More

    Direct Analysis of Aerosolized Chemical Warfare Simulants Captured on a Modified Glass-Based Substrate by 'Paper-Spray' Ionization.
    Anal Chem 2017 Sep 12. Epub 2017 Sep 12.
    Paper spray ionization mass spectrometry (PS-MS) offers a rapid alternative platform requiring no sample preparation. Aerosolized CWA simulants, trimethyl phosphate, dimethyl methylphosphonate, and diisopropyl methylphosphonate, were captured by passing air through a glass fiber filter disk and simultaneously capturing it directly onto a disposable paper spray cartridge. CWA simulants were aerosolized at varying concentrations using an in-house built aerosol chamber. Read More

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