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    32384 results match your criteria Analytical Chemistry [Journal]

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    Identification of Individual Bacterial Cells through the Intermolecular Interactions with Peptide-Functionalized Solid-State Pores.
    Anal Chem 2018 Jan 19. Epub 2018 Jan 19.
    The Institute of Scientific and Industrial Research, Osaka University , 8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
    Bioinspired pore sensing for selective detection of flagellated bacteria was investigated. The Au micropore wall surface was modified with a synthetic peptide designed from toll-like receptor 5 (TLR5) to mimic the pathogen-recognition capability. We found that intermolecular interactions between the TLR5-derived recognition peptides and flagella induce ligand-specific perturbations in the translocation dynamics of Escherichia coli, which facilitated the discrimination between the wild-type and flagellin-deletion mutant (ΔfliC) by the resistive pulse patterns thereby demonstrating the sensing of bacteria at a single-cell level. Read More

    A Microwell Array Method for Rapid Generation of Uniform Agarose Droplets and Beads for Single Molecule Analysis.
    Anal Chem 2018 Jan 19. Epub 2018 Jan 19.
    Compartmentalization of aqueous samples in uniform emulsion droplets has proven to be a useful tool for many chemical, biological, and biomedical applications. Herein, we introduce an array-based emulsification method for rapid and easy generation of monodisperse agarose-in-oil droplets in a PDMS microwell array. The microwells are filled with agarose solution, and subsequent addition of hot oil results in immediate formation of agarose droplets due to the surface-tension of the liquid solution. Read More

    Rapid sample pretreatment and accurate quantification of radiosulfur in chemically complex atmospheric samples.
    Anal Chem 2018 Jan 19. Epub 2018 Jan 19.
    An ultra-low-level liquid scintillation counting (LSC) technique has been used in measuring radiosulfur (cosmogenic 35S) in natural samples. The ideal half-life of 35S (~87 d) renders it a new way to examine various biogeochemical problems. A major limit of the technique is that complex chemical compositions in atmospheric samples may lead to color quenching of LSC cocktails, a serious problem prolonging the pretreatment time (>1 week) and hampering the accurate determination of 35S. Read More

    A Far-Red Fluorescent Probe for Imaging of Vicinal Dithiol-Containing Proteins in Living Cells Based on a pKa Shift Mechanism.
    Anal Chem 2018 Jan 19. Epub 2018 Jan 19.
    Vicinal dithiol-containing proteins (VDPs) play fundamental roles in intracellular redox homeostasis and are responsible for many diseases. In this work, we report a far-red fluorescence turn-on probe MCAs for VDPs exploiting the pKa shift of the imine functionality of the probe. MCAs is composed of a merocyanine Schiff base as the fluorescent reporter and a cyclic 1, 3, 2-dithiarsenolane as the specific ligand for VDPs. Read More

    Monitoring H2O2 inside Aspergillus fumigatus with an integrated microelectrode: the role of peroxiredoxin protein Prx1.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    In vivo studies on the degradation of exogenous hydrogen peroxide (H2O2) in the microenvironment of Aspergillus fumigatus fungus were performed by using an integrated Pt microelectrode. Three A. fumigatus strains were used to confirm the role of the cytosolic protein Prx1 on the defense mechanism of this microorganism: a wild-type strain, capable to express the protein Prx1; a Δprx strain, whose gene prx1 was removed; and a complemented Δprx1::prx1+ strain derivatized from the Δprx and in which the gene prx1 was re-introduced. Read More

    Enzyme-Initiated Quinone-Chitosan Conjugation Chemistry: Toward A General in Situ Strategy for High-Throughput Photoelectrochemical Enzymatic Bioanalysis.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China.
    Herein we report a general and novel strategy for high-throughput photoelectrochemical (PEC) enzymatic bioanalysis on the basis of enzyme-initiated quinone-chitosan conjugation chemistry (QCCC). Specifically, the strategy was illustrated by using a model quinones-generating oxidase of tyrosinase (Tyr) to catalytically produce 1,2-bezoquinone or its derivative, which can easily and selectively be conjugated onto the surface of the chitosan deposited PbS/NiO/FTO photocathode via the QCCC. Upon illumination, the covalently attached quinones could act as electron acceptors of PbS quantum dots (QDs), improving the photocurrent generation and thus allowing the elegant probing of Tyr activity. Read More

    Nanoscale imaging of primary cilia with scanning ion conductance microscopy.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    Primary cilia are hair-like sensory organelles whose dimensions and location vary with cell type and culture condition. Herein, we employed scanning ion conductance microscopy (SICM) to visualize the topography of primary cilia from different cell types. By combining SICM with fluorescence imaging, we successfully distinguished between surface cilia that project outward from the cell surface and subsurface cilia that are trapped below it. Read More

    A Cu-T1 sensor for versatile analysis.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    Conventional magnetic sensors usually employ Fe-based magnetic materials as signal probes. In this work, we find that Cu(II) is also a useful longitudinal relaxation time (T1) signal-based magnetic probe. We adopt bathocuproinedisulfonic acid disodium salt hydrate (BCS) to chelate Cu(I) and form a stable Cu(I)-BCS complex in aqueous solution, and find the significant difference in T1 value of water protons between Cu(II) aqueous solution and Cu(I)-BCS complex aqueous solution. Read More

    A Phosphorescent Trinuclear Gold(I) Pyrazolate Chemosensor for Silver Ion Detection and Remediation in Aqueous Media.
    Anal Chem 2018 Jan 17. Epub 2018 Jan 17.
    We report a phosphorescent chemosensor based on a trinuclear Au(I) pyrazolate complex or [Au(3-CH3,5-COOH)Pz]3, (aka Au3Pz3) stabilized in aqueous chitosan (CS) polymer media. Au3Pz3 is synthesized in situ within aqueous CS media at pH ~ 6.5 and room temperature (RT). Read More

    Determining Double Bond Position in Lipids Using Online Ozonolysis Coupled to Liquid Chromatography and Ion Mobility-Mass Spectrometry.
    Anal Chem 2018 Jan 17. Epub 2018 Jan 17.
    Department of Chemistry, Center for Innovative Technology, Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University , Nashville, Tennessee 37235, United States.
    The increasing focus on lipid metabolism has revealed a need for analytical techniques capable of structurally characterizing lipids with a high degree of specificity. Lipids can exist as any one of a large number of double bond positional isomers, which are indistinguishable by single-stage mass spectrometry alone. Ozonolysis reactions coupled to mass spectrometry have previously been demonstrated as a means for localizing double bonds in unsaturated lipids. Read More

    A method for high frequency underway N2 fixation measurements: Flow-through incubation Acetylene Reduction Assays by Cavity ring down laser Absorption Spectroscopy (FARACAS).
    Anal Chem 2018 Jan 17. Epub 2018 Jan 17.
    Because of the difficulty in resolving the large variability of N2 fixation with current methods which rely on discrete sampling, the development of new methods for high resolution measurements is highly desirable. We present a new method for high-frequency measurements of aquatic N2 fixation by continuous flow-through incubations and spectral monitoring of the acetylene (C2H2, a substrate analog for N2) reduction to ethylene (C2H4). In this method, named "Flow-through incubation Acetylene Reduction Assays by Cavity ring-down laser Absorption Spectros-copy" (FARACAS), dissolved C2H2 is continuously admixed with seawater upstream of a continuous-flow stirred-tank reactor (CFSR) in which C2H2 reduction takes place. Read More

    Sequential and Selective Detection of Two Molecules with a Single Solid-Contact Chronopotentiometric Ion-Selective Electrode.
    Anal Chem 2018 Jan 17. Epub 2018 Jan 17.
    A polymeric membrane ion-selective electrode (ISE) is typically designed for determination of one specific ion using conventional method. In this work, we demonstrate a simple, versatile and sensitive platform for simultaneous detection of two molecules with a single ISE. Under a series of periodic galvanostatic polarization, a solid-contact ISE without ion exchanger properties under zero-current conditions has been successfully used for simultaneous detection of two opposite charged ions with high sensitivity, good selectivity and fast reversibility. Read More

    First gut instincts are always right: the resolution required for a mass defect analysis of polymer ions can be as low as oligomeric.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Its recent adaptation to low-resolution mass spectra of polymers using fractional base units raises the question of the minimal resolution needed for a Kendrick mass defect (KMD) analysis. Intuiting an oligomeric resolution since the mass of a repeat unit is the sole value to be known, it is challenged by the relative failure of the KMD plots computed from an isotopically resolved MALDI-TOF mass spectrum to display clear alignments in the high mass range. Another procedure based on the remainders of Kendrick mass (RKMs) overcomes this pitfall with oligomers perfectly aligned in a new RKM plot. Read More

    Phasor-FLIM Analysis to Monitor Intercellular Drug Release from a pH-Sensitive Polymeric Nanocarrier.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    The design of highly efficient drug carriers, and the development of appropriate techniques to monitor their mechanism of action and therapeutic effect, are both critical for improving chemotherapy. Herein, a polymeric nanoparticle, PAH-Cit/DOX, was synthesized and used as a nano-drug system for the efficient delivery and pH-responsive release of doxorubicin (DOX) into cancer cells. The PAH-Cit/DOX nanoparticles were stable at physiological pH, but effectively released DOX under weakly acidic conditions. Read More

    Top-down hydrogen-deuterium exchange analysis of protein structures using ultraviolet photodissociation (UVPD).
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Top-down hydrogen-deuterium exchange (HDX) analysis using electron capture or transfer dissociation Fourier transform mass spectrometry is a powerful method for the analysis of secondary structure of proteins in solution. The resolution of the method is a function of the extensive fragmentation of backbone bonds in the proteins. While fragmentation is usually extensive near the N- and C-termini, electron capture (ECD) or electron transfer dissociation (ETD) fragmentation methods sometimes lack good coverage of certain regions of the protein - most often in the middle of the sequence. Read More

    A T1-Mediated Nanosensor for Immunoassay Based on Activatable MnO2 Nano-Assembly.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Current magnetic relaxation switching (MRS) sensors for detection of trace targets in complex samples still suffer from limitations in terms of relatively low sensitivity and poor stability. To meet this challenge, we develop a longitudinal relaxation time (T1)-based nanosensor by using Mn2+ released from the reduction of MnO2 nano-assembly that can induce the change of T1, thus can greatly improve the sensitivity and overcome the "hook effect" of conventional MRS. Through the specific interaction between antigen and antibody-functionalized MnO2 nano-assembly, the T1 signal of Mn2+ released from the nano-assembly is quantitatively determined by the antigen, which allows for highly sensitive and straightforward detection of targets. Read More

    A Smart Dual Quenching Strategy Enhances the Detection Sensitivity of Intracellular Furin.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Development of sensitive fluorescence "Turn-On" strategies for imaging enzyme activity in living cells is of disease-diagnostic importance but remains challenging. Herein, by employing a click condensation reaction and rational design of a single quenched probe Cys(StBu)-Lys(Gly-Lys(DABCYL)-Gly-Gly-Arg-Arg-Val-Arg-Gly-FITC)-CBT (1), we developed a "smart" dual quenching strategy and applied it to detect intracellular furin activity with enhanced sensitivity. At physiological condition, 1 was subjected to reduction-controlled condensation reaction to form 1-NPs and its fluorescence intensity further dropped to 1/2. Read More

    On the Validity of Measuring Metallic and Semiconducting SWCNT Fractions by Quantitative Raman Spectroscopy.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Although it is known that the Raman spectroscopic signature of single-walled carbon nanotubes (SWCNTs) is highly chirality dependent, using Raman spectroscopy as a tool for quantifying fraction of either metallic or semiconducting nanotubes in a sample has become a widely used analytical method. In this work, using the electron diffraction technique as a basis, we have examined the validity of Raman spectroscopy for quantitative evaluation of metallic fractions (M%) in single-walled carbon nanotube samples. Our results show that quantitative Raman spectroscopic evaluations of M%, either by using integrated intensities of chirality-associated radial breathing modes (RBMs), or, as has been more commonly utilized in recent studies, by statistically counting the numbers of RBMs, are misrepresentative. Read More

    The fate of poly(3-octylthiophene) transducer in solid contact ion-selective electrodes.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    An experimental approach allowing visualization and quantification of underestimated spontaneous process of partition of conducting polymer transducer material to the ion-selective membrane phase is proposed. The approach proposed is based on optical properties of the transducer material applied, using polythiophene as a model system. It is shown that this process occurs not only during sensor preparation step but also during pretreatment of the sensor before use. Read More

    A Novel Color Modulation Analysis Strategy through Tunable Multiband Laser for Nanoparticle Identification and Evaluation.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    Creating color difference and improving the color resolution in digital imaging is crucial for better application of color analy-sis. Herein, a novel color modulation analysis strategy was developed by using a homemade tunable multiband laser illumi-nation device, in which the portions of R, G, and B components of the illumination light are discretionarily adjustable, and hence the sample color could be visually modulated continuously in the RGB color space. Through this strategy, the color appearance of single gold nanorods (AuNRs) under dark-field microscopy, was migrated from the spectrally insensitive red region to the spectrally sensitive green-yellow-red region. Read More

    On-line preconcentration in capillaries by multiple large-volume sample stacking: an alternative to immunoassays for quantification of amyloid beta peptides biomarkers in cerebrospinal fluid.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    A novel electrokinetic preconcentration approach, so-called multiple pressure-assisted large-volume sample stacking with an electroosmotic flow pump (M-PA-LVSEP), was developed to allow in-capillary enrichment and separation of analytes from unlimited sample volumes. With this approach, the inherent limitation of in-capillary electrokinetic preconcentrations to the separation capillary volume can be overcome. The M-PA-LVSEP protocol relies on repeated cycles of pressure-assisted electroosmotic pumping and injection of extremely large sample volumes for analyte stacking and sample matrix removal. Read More

    Chromatographic separation and visual detection on wicking microfluidic devices: Quantitation of Cu2+ in surface-, ground-, and drinking water.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    Copper is widely applied in industrial and technological applications, and is an essential micro nutrient for humans and animals. However, exposure to high environmental levels of copper, especially through drinking water, can lead to copper toxicity, resulting in severe acute and chronic health effects. Therefore, regular monitoring of aqueous copper ions has become necessary as recent anthropogenic activities have led to elevated environmental concentrations of copper. Read More

    An Electrochemical System for the Study of Trans-Plasma Membrane Electron Transport in Whole Eukaryotic Cells.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    The development of new assays to study trans-plasma membrane electron transport (tPMET) in eukaryotic systems is paramount for a number reasons, which include the further understanding of the underlying biology which can then potentially be applied to innovate technological advancements in biosensing, microbial fuel, and pharmaceutical fields. The current literature provides methodology to study these systems that hinges upon mitochondrial knockout genotypes, or the detection of ferrocyanide using colorimetric methods. Developing a method to simultaneously analyze the redox state of a reporter molecule would give advantages in probing the underlying biology. Read More

    Impact of Nonideal Nanoparticles on XPS Quantitation: An Investigation Using Simulation and Modelling of Gold Nanoparticles.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    Quantitative X-ray photoelectron spectroscopic (XPS) analysis combined with spectral modeling of photoelectrons can be valuable while investigating the surface chemistry of nanoparticles (NPs) with different morphologies. Herein, with the use of NIST Simulation of Electron Spectra for Surface Analysis (SESSA), a comparative analysis of experimental and simulated photoelectron peak intensities in gold nanoparticles (AuNPs) of different morphologies is presented. Three sets of supported AuNPs with different morphologies were selected from a series of as synthesized Au-TiO2 catalyst samples. Read More

    A Highly Sensitive Ratiometric Self-Assembled Micellar Nanoprobe for Nitroxyl and Its Application In Vivo.
    Anal Chem 2018 Jan 15. Epub 2018 Jan 15.
    Nitroxyl (HNO) is a derivative of nitric oxide (NO) which plays an essential role in various biological and pharmacological events. Until now, the in situ trapping and specific detection of HNO in living samples is still challenging. In this project, we fabricated a novel BODIPY-based micellar nanoprobe for monitoring nitroxyl in vitro and in vivo in ratiometric mode in aqueous solution. Read More

    Analysis of gluten in a wheat gluten incurred sorghum beer brewed in the presence of proline endopeptidase by LC-MS/MS.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    Most gluten-reduced beers are produced using an enzyme called proline endopeptidase (PEP), which proteolyzes the gluten by cleaving at proline residues. However, the gluten content of beers brewed in the presence of PEP cannot be verified since current analytical methods are not able to accurately quantitate gluten in fermented foods. In this work, mass spectrometry was used to qualitatively characterize the gluten in a wheat gluten incurred sorghum model beer brewed with and without the addition of PEP. Read More

    Differentiation and Relative Quantitation of Disaccharide Iso-mers by MALDI-TOF/TOF Mass Spectrometry.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    Saccharide isomer differentiation has been a challenge in glycomics, as the lack of technology to decipher fully the diverse structures of compositions, linkages and anomeric configurations. Several mass spectrometry-based methods have been applied to the discrimination of disaccharide isomers, but limited quantitative analyses have been reported. In the present study, MALDI-LIFT-TOF/TOF has been investigated to differentiate and relatively quantify underivatized glucose-containing disaccharide isomers that differ in composition, connectivity or configuration. Read More

    Zeptomole Detection Scheme Based on Levitation Coordinate Measurements of a Single Microparticle in a Coupled Acoustic-Gravitational Field.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    We present a novel analytical principle in which an analyte (according to its concentration) induces a change in the density of a microparticle, which is measured as a vertical coordinate in a coupled acoustic-gravitational (CAG) field. The density change is caused by the binding of gold nanoparticles (AuNPs) on a polystyrene (PS) microparticle through avidin-biotin association. The density of a 10-m PS particle increases by 2 % when 500 100-nm AuNPs are bound to the PS. Read More

    Multispectral Atomic Force Microscopy-Infrared Nano-Imaging of Malaria Infected Red Blood Cells.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    Atomic Force Microscopy-Infrared (AFM-IR) spectroscopy is a powerful new technique that can be applied to study molecular composition of cells and tissues at the nano-scale. AFM-IR maps are acquired using single wavenumber value: they show either the absorbance plotted against a single wavenumber value, or a ratio of two absorbance values. Here we implement multivariate image analysis to generate multivariate AFM-IR maps, and use this approach to resolve subcellular structural information in red blood cells infected with Plasmodium falciparum at different stages of development. Read More

    A simple strategy for rapid and sensitive detection of avian influenza A H7N9 virus based on intensity-modulated SPR biosensor and new generated antibody.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    A new reassortant avian influenza A H7N9 virus have emerged in China since 2013, causing human infection with high mortality. An accurate and timely diagnosis is crucial for controlling the outbreaks of the disease. We therefore propose a simple strategy for rapidly and sensitively detecting the H7N9 virus using an intensity-modulated surface plasmon resonance (IM-SPR) biosensor integrated with a new generated monoclonal antibody. Read More

    Uranium (VI) on-chip microliter concentration measurements in a highly extended UV-Vis absorbance linearity range.
    Anal Chem 2018 Jan 12. Epub 2018 Jan 12.
    The reduction of effluents deriving from analytical control is a serious concern in the nuclear industry, for both production and R & D units. In this work we report an alternative methodology for the standard UV-Vis absorbance analyses for acti-nides concentration monitoring along the PUREX (Plutonium Uranium Redox Extraction) process. This methodology, based on Photonic Lab-on-a-chip (PhLoC) technology, enables drastic sampling reduction down to a few microliters, and simulta-neously allows to track concentrations over several orders of magnitude while maintaining a detection linearity range. Read More

    Microfluidic Device for Aptamer-based Cancer Cell Capture and Genetic Mutation Detection.
    Anal Chem 2018 Jan 11. Epub 2018 Jan 11.
    We present a microfluidic device for specifically capturing cancer cells and isolating their genomic DNA (gDNA) for specific amplification and sequence analysis. To capture cancer cells within the device, nucleic acid aptamers that specifically bind to cancer cells were immobilized within a channel containing micropillars designed to increase capture efficiency. The cap-tured cells were lysed in situ and their gDNA was isolated by physical entanglement within a second smaller-dimensioned micropillar array. Read More

    A pH-sensing optode for mapping spatiotemporal gradients in 3D paper-based cell cultures.
    Anal Chem 2018 Jan 11. Epub 2018 Jan 11.
    Paper-based cultures are an emerging platform for preparing 3D tissue-like structures. Chemical gradients can be imposed upon these cultures, generating microenvironments similar to those found in poorly vascularized tumors. There is increasing evidence that the tumor microenvironment is responsible for promoting drug resistance and increased invasiveness. Read More

    New Mechanism of Extractive Electrospray Ionization Mass Spectrometry for Heterogeneous Solid Particles.
    Anal Chem 2018 Jan 11. Epub 2018 Jan 11.
    Department of Chemistry, University of California-Irvine , Irvine, California 92697-2025, United States.
    Real-time in situ mass spectrometry analysis of airborne particles is important in several applications, including exposure studies in ambient air, industrial settings, and assessing impacts on visibility and climate. However, obtaining molecular and 3D structural information is more challenging, especially for heterogeneous solid or semisolid particles. We report a study of extractive electrospray ionization mass spectrometry (EESI-MS) for the analysis of solid particles with an organic coating. Read More

    Sensitive Detection of a Nerve-Agent Simulant through Retightening Internanofiber Binding for Fluorescence Enhancement.
    Anal Chem 2018 Jan 16. Epub 2018 Jan 16.
    Key Laboratory of Photochemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China.
    In this work, we develop fluorescent hierarchical nanofiber bundles 1, which involve the internanofiber hydrogen-bonding interactions, for rapid and sensitive detection of diethyl chlorophosphate (DCP) vapor. First, the internanofiber hydrogen-bonding strength can be weakened by photoexcitation, which thereby increases the internanofiber spacing and decreases the fluorescence intensity. Then, when exposed to trace DCP vapor, the strong interactions between DCP and hydroxyl groups on the nanofibers can effectively retighten the nanofibers and enhance the fluorescence as the detection signal. Read More

    Mass Spectrometric Quantitation of Tubulin Acetylation from Pepsin-Digested Rat Brain Tissue Using a Novel Stable Isotope Standard and Capture by Anti-Peptide Antibody (SISCAPA) Method.
    Anal Chem 2018 Jan 10. Epub 2018 Jan 10.
    Acetylation of α-tubulin at Lys-40 is a potential biomarker for cognitive deficits in various neurological disorders. However, this key PTM has not been previously studied with mass spectrometry, due to the inadequate distribution of tryptic cleavage sites. Following peptic digestion, a surrogate sequence containing this key PTM site was identified, and was found to be stable and quantitatively reproducible. Read More

    A polycapillary optics based confocal micro-XRF and XAS setup at ESRF CRG beamline DUBBLE, BM26A.
    Anal Chem 2018 Jan 10. Epub 2018 Jan 10.
    A novel plug-and-play setup based on polycapillary X-ray optics enables 3D confocal XRF and XAS down to 8×8×11 µm3 (17 keV) at the ESRF CRG beamline DUBBLE, BM26A. A complete description and analytical characterization is presented, together with 2 recently performed experimental cases. In Deep Earth diamond SL-FFM 16, an Olivine rich inclusion was mapped with full 3D XRF elemental imaging. Read More

    Super-Resolution Monitoring of Mitochondrial Dynamics upon Time-Gated Photo-Triggered Release of Nitric Oxide.
    Anal Chem 2018 Jan 10. Epub 2018 Jan 10.
    Nitric oxide (NO) potentially plays a regulatory role in mitochondrial fusion and fission, which are vital to cell survival and implicated in health, disease and ageing. Molecular tools facilitating study of the interrelationship between NO and mito-chondrial dynamics are in need. We have recently developed a novel NO donor (NOD550). Read More

    Enrichment and Quantitative Determination of 5-(hydroxymethyl)-2'-Deoxycytidine, 5-(formyl)-2'-Deoxycytidine, and 5-(carboxyl)-2'-Deoxycytidine in Human Urine of Breast Cancer by Magnetic High-cross-linked Microporous Polymers based on Poly-ionic Liquid.
    Anal Chem 2018 Jan 9. Epub 2018 Jan 9.
    5-(hydroxymethyl)-2'-deoxycytidine (5-hmdC), 5-(formyl)-2'-deoxycytidine (5-fodC), and 5-(carboxyl)-2'-deoxycytidine (5-cadC) are crucial intermediate products of DNA demethylation pathway, which can also act as potential biomarker reflecting the diagnosis and prognosis in multiple tumors. Detecting 5-hmdC, 5-fodC, and 5-cadC in human urine has various advantages including readily available samples and non-invasive to patients. However, few works have reported the detection of 5-fodC and 5-cadC due to their trace amounts. Read More

    Prussian Blue Nanoparticles as a Catalytic Label in a Sandwich Nanozyme-Linked Immunosorbent Assay.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    Institute of Analytical Chemistry, Czech Academy of Sciences , 602 00 Brno, Czech Republic.
    Enzyme immunoassays are widely used for detection of analytes within various samples. However, enzymes as labels suffer several disadvantages such as high production cost and limited stability. Catalytic nanoparticles (nanozymes) can be used as an alternative label in immunoassays overcoming the inherent disadvantages of enzymes. Read More

    Amyloid Beta Peptide VHHQ, KLVFF, and IIGLMVGGVV Domains Involved in Fibrilization: AFM and Electrochemical Characterization.
    Anal Chem 2018 Jan 9. Epub 2018 Jan 9.
    Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra , 3004-535, Coimbra, Portugal.
    The time-dependent structural modifications and oxidation behavior of specifically chosen five short amyloid beta (Aβ) peptides, Aβ1-16, Aβ1-28, Aβ10-20, Aβ12-28, and Aβ17-42, fragments of the complete human Aβ1-40 peptide, were investigated by atomic force microscopy (AFM) and voltammetry. The objective was to determine the influence of different Aβ domains (VHHQ that contains electroactive histidine H residues, KLVFF that is the peptide hydrophobic aggregation core, and IIGLMVGGVV that is the C-terminus hydrophobic region), and of Aβ peptide hydrophobicity, in the fibrilization mechanism. The short Aβ peptides absence of aggregation or the time-dependent aggregation mechanisms, at room temperature, in free chloride media, within the time window from 0 to 48 h, were established by AFM via changes in their adsorption morphology, and by differential pulse voltammetry, via modifications of the amino acid residues oxidation peak currents. Read More

    A microfluidic diffusion platform for characterizing the size of lipid vesicles and the thermodynamics of protein-lipid interactions.
    Anal Chem 2018 Jan 9. Epub 2018 Jan 9.
    Elucidation of the fundamental interactions of proteins with biological membranes under native conditions is crucial for understanding the molecular basis of their biological function and malfunction. Notably, the large surface to volume ratio of living cells provides a molecular landscape for significant interactions of cellular components with membranes modulating their function. However, such interactions can be challenging to probe using conventional biophysical methods due to the heterogeneity of the species and processes involved. Read More

    Improved Reversible Cross-linking-based Solid-phase RNA Extraction for Pathogen Diagnostics.
    Anal Chem 2018 Jan 9. Epub 2018 Jan 9.
    In this study, we developed an amine-functionalized, diatomaceous earth-based, dimethyl suberimidate assisted (ADD) system as a novel binding strategy to improve solid-phase extraction method for rapid and simple purification of RNA from biological samples including human cells and pathogenic bacteria. This ADD system is based on reversible cross-linking reactions between RNA and the silica matrix. The formation of robust covalent bonds protects RNA from both the sufferance of washing steps and isolation with ribonuclease (RNase)-rich samples, leading to the extraction of higher quality RNA. Read More

    Real-Time Monitoring of Urinary Encrustation Using a Quartz Crystal Microbalance.
    Anal Chem 2018 Jan 8. Epub 2018 Jan 8.
    Encrustation on the surface of urological devices such as ureteral stents leads to their blockage. However, limited tools are available for fast and real-time monitoring and modeling of the encrustation process. In this work, we have developed a model for in vitro study of encrustation and coupled it to an on-line monitoring QCM technique. Read More

    High-Throughput Monitoring of Cocaine and its Metabolites in Hair Using Microarrays for Mass Spectrometry and MALDI-MS/MS.
    Anal Chem 2018 Jan 8. Epub 2018 Jan 8.
    Due to inhomogeneous MALDI matrix crystallization and laser shot-to-shot variability, quantitation is not generally performed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Here we introduce a high-throughput MALDI method using an innovative high-density microarray for mass spectrometry (MAMS) technology, which allows semi-quantitative measurement of cocaine and its metabolites, benzoylecgonine, cocaethylene and ecgonine methyl ester. A MAMS slide containing lanes of hydrophilic spots and an automated slider to drag a sample droplet over several small spots can accomplish automatic sample aliquoting and lead to homogeneous crystallization of the matrix-analyte mixture and, thus, to a reproducible signal (average RSD 6%). Read More

    A Low-backpressure Single-Cell Point Constriction for Cytosolic Delivery based on Rapid Membrane Deformations.
    Anal Chem 2018 Jan 8. Epub 2018 Jan 8.
    Mechanically deforming biological cells through microfluidic constrictions is a recently introduced technique for the intracellular delivery of macromolecules possibly through transient membrane pores induced in the process. The technique is attractive for research and clinical applications mainly because it is simple, fast, and effective while being free of adverse effects often associated with well-known techniques that rely on field- or vector-based delivery. In this nascent approach, an utmost and crucial role is played by the constriction, often in rectangular profile and squeezes cells only in one dimension. Read More

    A Static and Dynamic Permeability Assay for Hydrophilic Small Molecules Using a Planar Droplet Interface Bilayer.
    Anal Chem 2018 Jan 8. Epub 2018 Jan 8.
    Because numerous drugs are administered through an oral route and primarily absorbed at the intestine by passive diffusion, the prediction of drug permeability across an intestinal epithelial cell membrane has been a crucial issue in drug discovery. Thus, various in vitro permeability assays have been developed such as the Caco-2 assay and the parallel artificial membrane permeability assay (PAMPA). However, due to the time-consuming and quite expensive process for culturing cells in the Caco-2 assays and the ambiguous membrane structures of the PAMPA, a simpler yet more accurate and versatile technique is still required. Read More

    Triple Signal Amplification Strategy for Ultrasensitive Determination of miRNA Based on Duplex Specific Nuclease and Bridge DNA-Gold Nanoparticles.
    Anal Chem 2018 Jan 18. Epub 2018 Jan 18.
    Shanghai Pulmonary Hospital, Tongji University School of Medicine , Shanghai, 200433 P. R. China.
    Abnormal expression of miRNAs always occurs in solid tumors. Thus, it is critical to sensitively and selectively detect such biomarkers for the diagnosis and prognosis of diseases. Here, we report a biosensing scheme for the determination of miRNA with triple signal amplification based on target-triggered cyclic duplex specific nuclease digestion and bridge DNA-gold nanoparticles. Read More

    Aptamer-Based Dual-Functional Probe for Rapid and Specific Counting and Imaging of MCF-7 Cells.
    Anal Chem 2018 Jan 19. Epub 2018 Jan 19.
    Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University , Wuhan 430072, China.
    Development of multimodal detection technologies for accurate diagnosis of cancer at early stages is in great demand. In this work, we report a novel approach using an aptamer-based dual-functional probe for rapid, sensitive, and specific counting and visualization of MCF-7 cells by inductively coupled plasma-mass spectrometry (ICP-MS) and fluorescence imaging. The probe consists of a recognition unit of aptamer to catch cancer cells specifically, a fluorescent dye (FAM) moiety for fluorescence resonance energy transfer (FRET)-based "off-on" fluorescence imaging as well as gold nanoparticles (Au NPs) tag for both ICP-MS quantification and fluorescence quenching. Read More

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