37,384 results match your criteria Analytical Chemistry [Journal]


NMR-based analysis of pomegranate juice using untargeted metabolomics coupled with nested and quantitative approaches.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Pomegranate juice is a complex mixture of structurally diverse compounds appearing in various concentrations. The composition of the final product depends on several factors such as the fruit variety, and the addition of adulterants. Its diverse composition makes pomegranate juice an excellent system for assessing the potential of an analytical method for targeted and untargeted analysis. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01553DOI Listing

Cryogenic Infrared Spectroscopy Reveals Structural Modularity in the Vibrational Fingerprints of Heparan Sulfate Diastereomers.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Heparan sulfate and heparin are highly acidic polysaccharides with a linear sequence, consisting of alternating glucosamine and hexuronic acid building blocks. The identity of hexuronic acid units shows a variability along their sequence, as D-glucuronic acid and its 5 epimer, L-iduronic acid can both occur. The resulting backbone diversity represents a major challenge for an unambiguous structural assignment by mass spectrometry-based techniques. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02048DOI Listing

Perspective on thin film waveguides for on-chip mid-infrared spectroscopy of liquid biochemical analytes.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Miniaturized spectrometers offering low cost, low reagent consumption, high throughput, sensitivity and automation are the future of sensing and have significant applications in environmental monitoring and food safety, biotechnology, pharmaceuticals and healthcare. Mid-infrared (MIR) spectroscopy employing complementary metal oxide semiconductor (CMOS) compatible thin film waveguides and microfluidics shows great promise towards highly integrated and robust detection tools and liquid handling. This perspective provides an overview of emergence of thin film optical waveguides used for evanescent field sensing of liquid chemical and biological samples for MIR absorption spectroscopy. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01296DOI Listing

Tracking of Solution-Phase Concentration Profiles in Li-ion Battery Positive Electrodes using X-Ray Fluorescence.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

The trade-off between energy density and power capabilities is a challenge for Li-ion battery design as it highly depends on the complex porous structures that holds the liquid electrolyte. Specifically, mass-transport limitations lead to large concentration gradients in the solution-phase and subsequently to crippling overpotentials. The direct study of these solution-phase concentration profiles in Li-ion battery positive electrodes has been elusive, in part because they are shielded by an opaque and paramagnetic matrix. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02086DOI Listing

Comparative analysis of cleavage specificities of immobilized porcine pepsin and Nepenthesin II under HDX conditions.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Hydrogen/Deuterium Exchange (HDX) coupled with Mass Spectrometry (HDX-MS) is a sensitive and robust method to probe protein conformational changes and protein-ligand interactions. HDX-MS relies on successful proteolytic digestion of target proteins under acidic conditions to localize perturbations in exchange behavior to protein structure. The ability of the protease to produce small peptides and overlapping fragments and provide sufficient coverage of the protein sequence is essential for localizing regions of interest. Read More

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http://dx.doi.org/10.1021/acs.analchem.9b05694DOI Listing

microorganism@UiO-66-NH2 composites for the detection of multiple colorectal cancer-related microRNAs with flow cytometry.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

High-throughput analyses of multitarget markers can facilitate rapid and accurate clinical diagnosis. Suspension array assays, a flow cytometry-based analysis technology, are among some of the most promising multi-component analysis methods for clinical diagnostics and research purposes. These assays are appropriate for examining low-volume, complex samples having trace amounts of analytes due to superior elimination of background. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02017DOI Listing

Real-time imaging redox status in biothiols and ferric metabolism of cancer cells in ferroptosis based on switched fluorescence response of gold carbon dots.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Ferroptosis is an iron-dependent form of regulated cell death. In this study, a ratiometric fluorescent probe, gold carbon dots (GCDs) consisting of carbon skeleton and gold nanoclusters, was used for in situ imaging to monitor redox status in biothiols (glutathione and cysteine) and ferric metabolism of cancer cells in ferroptosis. The as-prepared GCDs can selectively respond to biothiols, interestingly, the fluorescence may be switched to sense ferric ions without being interfered by biothiols under proper conditions. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02420DOI Listing

Mass Defect-based DiLeu Tagging for Multiplexed Data-Independent Acquisition.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

The unbiased selection of peptide precursors makes data-independent acquisition (DIA) an advantageous alternative to data-dependent acquisition (DDA) for discovery proteomics, but traditional multiplexed quantification approaches employing mass difference labeling or isobaric tagging are incompatible with DIA. Here, we describe a strategy that permits multiplexed quantification by DIA using mass defect-based N,N-dimethyl leucine (mdDiLeu) tags and high-resolution tandem mass spectrometry (MS2) analysis. Millidalton mass differences between mdDiLeu isotopologues produce fragment ion multiplet peaks separated in mass by as little as 5. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01136DOI Listing

Software requirements for the analysis and interpretation of native ion mobility mass spectrometry data.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

The last few years have seen a dramatic increase in applications of native mass and ion mobility spectrometry, especially for the study of proteins and protein complexes. This increase has been catalysed by the availability of commercial instrumentation capable of carrying out such analyses. As in most fields, however, the software to process the data generated from new instrumentation lags behind. Read More

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http://dx.doi.org/10.1021/acs.analchem.9b05792DOI Listing

Achieving non-enzymatic blood glucose sensing by uprooting saturation.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

The saturation of non-enzymatic blood glucose sensors at lower than normal blood glucose levels has blocked their practical applications. The mechanistic understanding of the saturation, however, has long been under debate. Employing cyclic volt-ammetry, amperometry and FTIR with various electrolyte of varying concentration, we were able to uproot the saturation cause. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02218DOI Listing

Please Avoid Plotting Analytical Response against Logarithm of Concentration.

Authors:
Pawel L Urban

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

This perspective highlights a malpractice in handling calibration datasets. It refers to relating analytical response with logarithm of concentration, fitting such a dataset with linear function, and deriving method characteristics from the slope of that function. A distinction is made between this malpractice and the proper use of logarithmic plots in representation of calibration datasets. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02096DOI Listing

Conversion efficiencies of a few living microbial cells detected at high throughput by droplet-based ESI-MS.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

Label-free and sensitive detection of synthesis products from single microbial cells remains the bottleneck for determining the specific turnover numbers of individual whole-cell biocatalysts. We demonstrate the detection of lysine synthesized by only a few living cells in microfluidic droplets via mass spectrometry. Biocatalyst turnover numbers were analyzed using rationally designed reaction environments compatible with mass spectrometry, decoupled from cell growth, with high specific turnover rates (~1 fmol cell h), high conversion yields (25%), and long-term catalyst stability (>14h). Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01839DOI Listing

Combinatory data independent acquisition and parallel reaction monitoring method for deep profiling of gangliosides.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

Ganglioside is an important class of lipid species involving in intercellular signaling and various diseases, especially for neurodegenerative diseases. Systematic ganglioside profiling is challenging due to their naturally low abundance and highly diverse species. Herein, a new data independent acquisition and parallel reaction monitoring (DIA/PRM) method with superior sensitivity was developed. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02313DOI Listing

Correlation-based Deconvolution (CorrDec) to generate high-quality MS2 spectra from data-independent acquisition in multi-sample studies.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

Data-independent acquisition mass spectrometry (DIA-MS) is essential for information-rich spectral annotations in untargeted metabolomics. However, the acquired MS2 spectra are highly complex, posing significant annotation challenges. We have developed a correlation-based deconvolution (CorrDec) method that uses ion abundance correlations in multi-sample studies using DIA-MS as an update of our MS-DIAL software. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01980DOI Listing

In-situ hydrogel extraction with dual-enzyme digestion of proteinaceous binders: the key for reliable mass spectrometry investigations of artworks.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

A novel strategy based on in-situ dual-enzyme digestion of paint layers proteinaceous binders is introduced for faster and more confident identification, ensuing a bottom-up proteomics approach by MALDI-TOF mass spectrometry (MS). In-situ sampling/extraction of proteinaceous binders using small pieces of a hydrophilic gel, previously loaded with trypsin and chymotrypsin proteolytic enzymes, was successfully exploited. Along with minimal invasiveness, the synergy of both enzymes was very useful to increase the number of annotated peptide peaks with their corresponding amino acid sequence by database search and subsequent MALDI-TOF/TOF analysis. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01898DOI Listing

Halogen Effects-Induced Bright D-π-A Fluorophore as Scaffold for NIR Fluorogenic Probes with High Contrast.

Anal Chem 2020 Jul 10. Epub 2020 Jul 10.

Endowing fluorogenic probes with ultrahigh contrast is essential to increasing the accuracy of fluorescence sensing and imaging. Phenolate-based D-π-A fluorophores (A-DOH) belong to a big family of fluorophores and have attracted increasing attention in fluorogenic probe design. However, the intrinsic dilemma of weak intracellular emission of traditional A-DOH fluorophores resulted in low contrast during live cell imaging. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02247DOI Listing

3D DNA Nanomachine Biosensor by Integrating DNA Walker and Rolling Machine Cascade Amplification for Ultrasensitive Detection of Cancer-Related Gene.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

Stochastic DNA walkers capable of traversing on three-dimensional (3D) tracks have received great attentions. However, DNA walker-based biosensors exhibit limited amplification efficiency due to their slow walking kinetics and low processivity. Herein, by taking advantage of the high processivity of DNA rolling machine, a sensitive ratiometric DNA nanomachine biosensor is designed. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01074DOI Listing

Sensitive Detection of Separated Charges in Nanohybrids by Laser Excitation Mass Spectrometry with Tetrabutylammonium Cationic Probe.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

Charge separation lays the foundation for photocatalysis and photovoltaics, in which the catalytic/ voltaic efficiency is primarily related to the amount of separated charges generated. Yet, direct experimental approaches for the quantification of separated charges are very limited, especially for nanostructures in a small quantity. Here, by laser excitation mass spectrometry with tetrabutylammonium as a sensitive probe, the separated charges in gold-metal sulfide core-shell nanostructures are determined and correlated with the bandgap of the semiconductor shell. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01934DOI Listing

Expanding the depth and sensitivity of cross-link identification by differential ion mobility using FAIMS.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

In cross-linking mass spectrometry (XL-MS), the depth and sensitivity of cross-link detection is often limited by the low abundance of cross-links compared to non-cross-linked peptides in the digestion mixture. To improve the identification efficiency of cross-links, here we present a gas-phase separation strategy using high field asymmetric waveform ion mobility spectrometry (FAIMS) coupled to the Orbitrap Tribrid mass spectrometers. By enabling an additional peptide separation step in gas phase using the FAIMS device, we increase the number of cross-link identification by 22% for a medium complex sample and 59% for strong cation exchange-fractionated HEK293T cell lysate in XL-MS experiments using disuccinimidyl sulfoxide (DSSO) cross-linker. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01273DOI Listing

Ultra-sensitive multiplex detection of single nucleotide polymorphisms based on short-chain hybridization combined with on-line preconcentration of capillary electrophoresis.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

Reliably multiple single nucleotide polymorphisms (SNPs) detection at low abundance is of great significance for diseases diagnosis and biomedical research. Herein, we have developed a novel and simple method for multiple SNPs detection combining solid-phase capture by specific hybridization with on-line preconcentration of capillary gel electrophoresis-laser-induced fluorescence (CGE-LIF). The method presents an excellent performance due to its favorable traits: the solid-phase short-chain hybridization ensures the high specificity of SNP detection; the effective separation ability of CGE can easily achieve multiplex detection; the simple on-line preconcentration significantly improves the detection sensitivity of fluorescent probe by nearly 100 folds. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01675DOI Listing

A single-cell multimodal analytical approach by integrating Raman optical tweezers and RNA sequencing.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

Single-cell analysis has become a state-of-art approach to heterogeneity profiling in tumor cells. Herein, we realize a kind of single-cell multimodal analytical approach by combining single-cell RNA sequencing (scRNA-seq) with Raman optical tweezers (ROT), a label-free single-cell identification and isolation technique, and apply it to investigate drug sensitivity. The drug sensitivity of human BGC823 gastric cancer cells towards different drugs, paclitaxel and sodium dichloroacetate, was distinguished in the conjoint analytical way including morphology monitoring, Raman identification and transcriptomic profiling. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00912DOI Listing

Charge Storage in Graphene Oxide: The Impact of the Cation on Ion Permeability and Interfacial Capacitance.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

The charge storage and membrane applications of graphene oxide (GO) materials are dictated by its intrinsic material properties. Structure-function relationships correlating periodic parameters, such as hydrated ion radius, to ion-GO interactions are currently lacking and needed to provide insight into the charge storage and ion transport mechanism. We report the use of scanning ion conductance microscopy to measure the ion permeability of GO films and evaluate its relationship with the measured capacitance. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00218DOI Listing

Parallel Ionic Liquid Semi-Packed Microfabricated Columns for Complex Gas Analysis.

Anal Chem 2020 Jul 9. Epub 2020 Jul 9.

The paper presents a parallel micro gas chromatography approach using three ionic liquid semi-packed columns. Switching from a single column to multiple parallel columns with different selectivity enhances the power of compound identification without increasing the analysis time. The columns are fabricated using microelectromechanical systems (MEMS) technology containing an array of microfabricated pillars. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01721DOI Listing

Challenging a preconception: Optoacoustic spectrum differs from the absorption spectrum of proteins and dyes for molecular imaging.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Optoacoustic (photoacoustic) imaging has seen marked advances in detection and data analysis, but there is less progress in understanding the photophysics of common optoacoustic contrast agents. This gap blocks the development of novel agents and the accurate analysis and interpretation of multispectral optoacoustic images. To close it, we developed a multi-modal laser spectrometer (MLS) to enable the simultaneous measurement of optoacoustic, absorbance, and fluorescence spectra. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01902DOI Listing

Increasing the coverage of a mass spectral library of milk oligosaccharides using a hybrid-search-based bootstrapping method and milks from a wide variety of mammals.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

This study significantly expands both the scope and method of identification for construction of a previously reported tandem mass spectral library of 74 human milk oligosaccharides (HMOs) derived from results of combined LC-MS/MS experiments and comprehensive structural analysis of HMOs. In the present work, a hybrid search 'bootstrap' identification method was employed that substantially broadens the coverage of milk oligosaccharides and thereby increase utility use of a spectrum library-based method for the rapid tentative identification of all distinguishable glycans in milk. This involved hybrid searching of the previous library, which was itself constructed using the hybrid search of oligosaccharide spectra in the NIST 17 Tandem MS Library. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00342DOI Listing

In situ Quantitatively Observing Hygroscopic Growth of Single Nanoparticle Aerosol by Surface Plasmon Resonance Microscope.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Aerosol particles hygroscopicity is an important factor in visibility reduction, cloud formation, radiation forcing and the global climate. The high number concentration of nanoparticles (defined as particles with diameters below 100 nm) means that their hygroscopic growth abilities and potential contributions to the climate and environment ar¬e significant. Therefore, a rapid and accurate in situ analysis method for single nanoparticle hygroscopic growth in an atmospheric environment is important to characterize the effects of the particle's physical and chemical properties in this process. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00431DOI Listing

An Integrated Approach for Characterizing Bispecific Antibody/Antigens Complexes and Mapping Binding Epitopes with SEC/MALS, Native Mass Spectrometry and Protein Footprinting.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Bispecific antibodies (BsAbs), with a unique mechanism of recognizing two different epitopes or antigens, have shown potential in various therapeutic areas. Molecular characterization of BsAbs' epitopes not only allows detailed understanding of their mechanism of actions, but also guides the design and selection of drug candidate molecules. In this study, we illustrate the practical utility of an integrated approach, including size exclusion chromatography with multi-angle light scattering and native mass spectrometry (MS), for the biophysical characterization of complex formation of a BsAb with two target antigens, cluster of differentiation 3 (CD3) and B-cell maturation antigen (BCMA). Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01876DOI Listing

Antibody-free targeted proteomics assay for absolute measurement of α-tubulin acetylation.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Acetylation of α-tubulin at conserved lysine 40 (K40) amino acid residue regulates microtubule dynamics and controls a wide range of cellular activities. Dysregulated microtubule dynamics characterised by differential α-tubulin acetylation is a hallmark of cancer, neurodegeneration and other complex disorders. Hence, accurate quantitation of α-tubulin acetylation is required in human disease and animal model studies. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01683DOI Listing

Automated Coupling of Nanodroplet Sample Preparation with Liquid Chromatography-Mass Spectrometry for High-Throughput Single-Cell Proteomics.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Single-cell proteomics can provide critical biological insight into the cellular heterogeneity that is masked by bulk-scale analysis. We have developed a nanoPOTS (nanodroplet processing in one pot for trace samples) platform and demonstrated its broad applicability for single-cell proteomics. However, because of nanoliter-scale sample volumes, the nanoPOTS platform is not compatible with automated LC-MS systems, which significantly limits sample throughput and robustness. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01551DOI Listing

Proton transfer reactions for the gas-phase separation, concentration, and identification of cardiolipins.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

Cardiolipin (CL) analysis demands high specificity, due to the extensive diversity of CL structures, and high sensitivity, due to their low relative abundance within the lipidome. While electrospray ionization mass spectrometry (ESI-MS) is the most widely used technology in lipidomics, the potential for multiple charging presents unique challenges for CL identification and quantification. Depending on the conditions, ESI-MS of lipid extracts in negative ion mode can give rise to cardiolipins ionized as both singly and doubly deprotonated anions. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02545DOI Listing

Solid-phase PCR-amplified DNAzyme activity for real-time FO-SPR detection of the MCR-2 gene.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

The polymerase chain reaction (PCR) has been the gold standard molecular analysis technique for decades and has seen quite some evolution in terms of reaction components, methodology and readout mechanisms. Nucleic acid enzymes (NAzymes) have been used to further exploit the applications of PCR, but so far the work was limited to the colorimetric G-quadruplex or fluorescent substrate cleaving NAzymes. In this study, a solid-phase, fiber optic surface plasmon resonance (FO-SPR) technique is presented as an alternative read-out for PCR utilizing NAzymes. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02241DOI Listing

A biocompatible fluorescent probe for selective detection of amyloid fibrils.

Anal Chem 2020 Jul 7. Epub 2020 Jul 7.

The misfolding and aggregation of proteins leading to amyloid formation has been linked to numerous diseases, necessitating the development of tools to monitor the fibrillation process. Here, we report an intramolecular charge transfer (ICT) dye, DMNDC, as an alternative to thioflavin-T (ThT), most commonly used for monitoring amyloid fibrils. Using insulin as a model protein, we show that DMNDC efficiently reports on the kinetics of fibril formation. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00379DOI Listing

An open space diffusive filter for simultaneous species retrieval and separation.

Anal Chem 2020 Jul 8. Epub 2020 Jul 8.

We present a novel method for the local retrieval of surface bound species and their rapid in-line separation using an open space microfluidic device. Separation can be performed in less than 30 seconds using the difference in diffusivities within parallel microfluidic flows. As a proof-of-principle, we report the rapid and efficient filtration of polystyrene beads from small molecules, and surface bound red blood cells from dimethyl sulphoxide for antigen typing. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02176DOI Listing

3D Nanoscale Chemical Imaging of Core-Shell Microspheres via Microlensed Fiber Laser Desorption Postionization Mass Spectrometry.

Anal Chem 2020 Jul 7. Epub 2020 Jul 7.

Ministry of Education (MOE) Key Laboratory of Spectrochemical Analysis and Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University,Xiamen 361005, China.

A laser desorption postionization (LDPI) nanoscale resolution mass spectrometry imaging (MSI) technique based on a microlensed fiber is proposed for 3D imaging of microspheres which have a core-shell structure. Results show that the diameter of the sampling crater can be as small as 350 nm by introducing the desorption laser to the sample surface through the microlensed fiber. The use of laser postionization greatly solves the problem of weak signal caused by the very small sampling amount. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01434DOI Listing

A Comprehensive Targeted Metabolomic Assay for Urine Analysis.

Anal Chem 2020 Jul 7. Epub 2020 Jul 7.

Among all the human biological fluids used for disease biomarker discovery or clinical chemistry, urine stands out. It can be col-lected easily and non-invasively, it is readily available in large volumes, it is typically free from protein contamination and it is chemically complex - reflecting a wide range of physiological states and functions. However, the comprehensive metabolomic analysis of urine has been somewhat less studied compared to blood. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01682DOI Listing

Probing Microbial Extracellular Respiration Ability Using Riboflavin.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Electrochemically active bacteria (EAB) are capable of extracellular electron transfer (EET) to insoluble metal oxides, and thus play a great role in the fields of environment, energy and geosciences. However, rapid and accurate quantification of the EET ability of EAB is still challenging. In this work, we develop a riboflavin-based fluorescent method for facile, accurate and in-situ measurement of the EET ability of EAB. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01650DOI Listing

Enabling Flow-based Kinetic Off-rate Selections using a Microfluidic Enrichment Device (MFED).

Anal Chem 2020 Jul 7. Epub 2020 Jul 7.

Modern genomic sequencing efforts are identifying potential diagnostic and therapeutic targets more rapidly than existing methods can generate the peptide- and protein-based ligands required to study them. To address this problem, we have developed a Microfluidic Enrichment Device (MFED) enabling kinetic off-rate selection without the use of exogenous competitor. We tuned the conditions of the device (bed volume, flow rate, immobilized target) such that modest, readily achievable changes in flow rates favor formation or dissociation of target-ligand complexes based on affinity. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01867DOI Listing

Single-Particle Mobility Analysis Enables Ratiometric Detection of Cancer Markers under Darkfield Tracking Microscopy.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Here we introduced a single-particle mobility analysis based ratiometric strategy for quantitative detection of disease-related biomarkers using antibody-conjugated gold nanoparticles (AuNPs) as probes under darkfield tracking microscopy (DFTM). Based on the capability of discriminating nanoparticles with different hydrodynamic sizes and detecting the changes in hydrodynamic effect, single-particle mobility analysis enables us to determine the amount of aggregated and monodispersed nanoprobes for the sandwich-like immunoassay strategy, making it possible to quantify the biotargets by analyzing the relative changes in aggregate-to-monomer ratio of nanoprobes. By using capture antibody and detection antibody conjugated AuNPs as nanoprobes, we demonstrated ratiometric detection of carcinoembryonic antigen (CEA) over a linear dynamic range from 50 pM to 750 pM, which is competent for clinic diagnostic analysis of CEA in tumor patients. Read More

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http://dx.doi.org/10.1021/acs.analchem.9b05512DOI Listing

AFM-Based High-Throughput Nanomechanical Screening of Single Extracellular Vesicles.

Anal Chem 2020 Jul 13. Epub 2020 Jul 13.

Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, 50019 Firenze, Italy.

The mechanical properties of extracellular vesicles (EVs) are known to influence their biological function, in terms of, e.g., cellular adhesion, endo/exocytosis, cellular uptake, and mechanosensing. Read More

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http://dx.doi.org/10.1021/acs.analchem.9b05716DOI Listing

On-MALDI-target N-glycan nonreductive amination by 2-aminobenzoic acid.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

2-aminobenzoic acid (2-AA) is widely used as a labeling reagent to derivatize released N-glycans at their free reducing terminus by reductive amination. 2-AA labeled glycans have increased mass spectrometric sensitivity for their identification and enable fluorescence-chromatography based glycan quantification. Drawbacks are that the labeling process is labor intensive and time consuming. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01748DOI Listing

Proteomics Using Protease Alternatives to Trypsin Benefits from Sequential Digestion with Trypsin.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, 13355, Berlin, Germany.

Trypsin is the most used enzyme in proteomics. Nevertheless, proteases with complementary cleavage specificity have been applied in special circumstances. In this work, we analyzed the characteristics of five protease alternatives to trypsin for protein identification and sequence coverage when applied to whole cell lysates. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00478DOI Listing

A Combination of FAIMS, Protein A Depletion, and Native Digest Conditions Enables Deep Proteomic Profiling of Host Cell Proteins in Monoclonal Antibodies.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Host cell proteins (HCPs) are residual impurities generated by the expression cell line during the production of biopharmaceuticals. Although the majority of these contaminants are removed during purification, HCPs can represent a considerable risk to the efficacy and safety of a therapeutic protein if not actively monitored. The enzyme-linked immunosorbent assay (ELISA) is commonly used throughout production to monitor HCP levels but has limited ability to identify novel HCPs or provide detailed quantification. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01175DOI Listing

Comparison of Disk and Nano-tip Electrodes for Measurement of Single-Cell Amperometry during Exocytotic Release.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

We compare single-cell amperometric measurements of exocytosis from PC12 cells between two types of elec-trodes, carbon fiber disk microelectrodes and nano-tip conical-shape carbon fiber microelectrodes. During the exocytotic process, individual exocytotic release events, measured as current spikes at the electrode offer quantitative and dynamic information about chemical release from cells. Using two electrodes gives rise to unequal distance between the fusion pore and the electrode as well as fusion pore size, which leads to differ-ent average spike shapes. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02013DOI Listing

rPTMDetermine: A Fully Automated Methodology for Endogenous Tyrosine Nitration Validation, Site-Localization, and Beyond.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

We present herein rPTMDetermine, an adaptive and fully automated methodology for the validation of identifications of rarely occurring post-translational modifications (PTMs) using a semi-supervised approach with a linear discriminant analysis (LDA) algorithm. In addition, verification was enhanced by similarity scoring on tandem mass spectrometry (MS/MS) comparisons between modified peptides and their unmodified analogues. We have applied rPTMDetermine to (1) perform fully automated validation steps for modified peptides identified from an in silico database and (2) retrieve potential yet-to-be-identified modified peptides from raw data, but missed through conventional database search. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02148DOI Listing

Indicator Dyes and Catalytic Nanoparticles for Irreversible Visual Hydrogen Sensing.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Using ultraviolet-visible (UV Vis) absorption spectroscopy, we have tested the reactivity of various indicator molecules combined with catalytic bimetallic gold-palladium nanoparticles (Au-Pd NPs) in solution for irreversible, and visual response to H2 with the aim to develop the most suitable indicator/Au-Pd NP system into a thin, wearable, and visual H2 sensor for non invasive monitoring of in vivo Mg implant biodegradation in research and clinical settings with fast response time. The indicators studied were bromothymol blue, methyl red, and resazurin, and the reactions of each system with H2 in the presence of Au-Pd NPs caused visual and irreversible color changes that were concluded to proceed via redox processes. The Resazurin/Au Pd NP system was deemed best suited for our research objectives because (1) this system had the fastest color change response to H2 at levels relevant to in vivo Mg-implant biodegradation compared to the other indicator/Au-Pd NP systems tested, (2) the observed redox chemistry with H2 followed well-understood reaction pathways reported in the literature, and (3) the redox products were non toxic and appropriate for medical applications. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01769DOI Listing

HYBRIDIZATION LC-MS/MS: AN ALTERNATIVE BIOANALYTICAL METHOD FOR ANTI-SENSE OLIGONUCLEOTIDE QUANTITATION IN PLASMA AND TISSUE SAMPLES.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Quantitative bioanalysis in plasma and tissues samples are required to study the pharmacokinetic and pharmacodynamic properties of antisense oligonucleotides (ASOs). To overcome intrinsic drawbacks in specificity, sensitivity and throughput of traditional ligand-binding assay (LBA) and LC-MS/MS methods, an alternative bioanalytical method was developed by combining oligonucleotide hybridization and LC-MS/MS technologies. Target ASOs were extracted from biological samples by hybridization with biotinylated sense-strand oligonucleotides coupled to streptavidin magnetic beads. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c01382DOI Listing

On-line nano-solid phase extraction Fourier-transform ion cyclotron resonance mass spectrometry workflow to analyze small scale gradients of soil solution organic matter in the rhizosphere.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

A new method combining on-line nano-solid phase extraction coupled with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was developed to extract and analyze organic matter (OM) from microliter volumes of salt containing soil solution samples. The system allows the reproducible analysis of only minute amounts of organic carbon (down to 10 ng C) without the need of further sample preparation. The new method was applied to unravel developing small-scale patterns of dissolved organic matter (DOM) in soil solution of a soil column experiment in which Zea mays plants were grown for three weeks. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c00946DOI Listing

Chemical Class Prediction of Unknown Biomolecules Using Ion Mobility-Mass Spectrometry and Machine Learning: SIFTER.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

This work presents a machine learning algorithm referred to as the Supervised Inference of Feature Taxonomy from Ensemble Randomization (SIFTER), which supports the identification of features derived from untargeted ion mobility-mass spectrometry (IM-MS) experiments. SIFTER utilizes random forest machine learning on three analytical measurements derived from IM-MS (collision cross section, CCS), mass-to-charge (m/z), and mass defect (Δm)) to classify unknown features into a taxonomy of chemical kingdom, super class, class, and subclass. Each of these classifications is assigned a calculated probability as well as alternate classifications with associated probabilities. Read More

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http://dx.doi.org/10.1021/acs.analchem.0c02137DOI Listing

Resolution of Isomeric Mixtures in Ion Mobility Using a Combined Demultiplexing and Peak Deconvolution Technique.

Anal Chem 2020 Jul 6. Epub 2020 Jul 6.

Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States.

A combined data acquisition and data processing strategy for improving the sensitivity and resolution of ion mobility measurements is described. This strategy is implemented on a commercially available drift tube ion mobility-mass spectrometry (IM-MS) instrument and utilizes both an existing ion multiplexing strategy to achieve up to an 8-fold gain in ion signal and a new postacquisition data reconstruction technique, termed "high resolution demultiplexing" (HRdm), to improve resolution in the ion mobility dimension. A series of isomeric mixtures were qualitatively investigated with HRdm, including biologically relevant lipids and carbohydrates, which were successfully resolved by HRdm, including two monosaccharide regioisomers which differed in drift time by only 0. Read More

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http://dx.doi.org/10.1021/acs.analchem.9b05718DOI Listing