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Analytical Chemistry

Zdeněk Farka, Tomáš Juřík, Matěj Pastucha, Petr Skládal
Contamination of food by pathogenic bacteria has always been a serious threat for human health. The amount of food exports and imports has been increasing in recent years which requires precise food quality control with short analysis time and simplified sample treatment. Surface plasmon resonance (SPR) immunosensor enhanced by biocatalyzed precipitation was developed for the analysis of Salmonella in dairy products. The specific capture antibody was immobilized on the SPR chip which allowed a direct label-free detection of Salmonella Typhimurium with the limit of detection (LOD) of 10^4 CFU·mL-1 and the analysis time of 10 min...
November 4, 2016: Analytical Chemistry
Gabor Jarvas, Marton Szigeti, Jeff Chapman, Andras Guttman
Despite the ever growing use of capillary electrophoresis in biomedical research and the biopharmaceutical industry, the de-velopment of data interpretation methods is lagging behind. In this paper we report the design and implementation of a co-injected triple-internal standard method, to alleviate the need of an accompanying run of the maltooligosaccharide ladder for glucose unit (GU) calculation. Based on the migration times of the co-injected standards of maltose, maltotriose and maltopentadecaose (bracketing the peaks of interest), a data processing approach was designed and developed to set up a virtual ladder that was used for GU calculation...
November 4, 2016: Analytical Chemistry
Andrew T Csordas, Anna Jørgensen, Jinpeng Wang, Emily Gruber, Qiang Gong, Elizabeth R Bagley, Margaret A Nakamoto, Michael Eisenstein, H Tom Soh
Sandwich assays are among the most powerful tools in molecular detection. These assays use "pairs" of affinity reagents so that the detection signal is generated only when both reagents bind simultaneously to different sites on the target molecule, enabling highly sensitive and specific measurements in complex samples. Thus, the capability to efficiently screen affinity reagent pairs at a high throughput is critical. In this work, we describe an experimental strategy for screening "aptamer pairs" at a throughput of 10(6) aptamer pairs per hour-which is many orders of magnitude higher than the current state of the art...
November 4, 2016: Analytical Chemistry
Keliang Shi, Xiaolin Hou, Jixin Qiao, Xuejie Sun, Per Roos, Wangsuo Wu
An extremely high accumulation and retention of technetium in marine plants especially brown seaweed makes it a unique bio-indicator of technetium. In the present work, a novel approach was developed for the speciation analysis of technetium in seaweed, wherein a series of biochemical separations was exploited to isolate different species of technetium. Inductively coupled plasma mass spectrometry (ICP-MS) was applied for the measurement of 99Tc after thorough radiochemical pre-concentration and purification...
November 4, 2016: Analytical Chemistry
John D Barr, Liuqing Shi, David H Russell, David E Clemmer, Alison E Holliday
Ion mobility spectrometry (IMS) is increasingly used to describe solution-phase phenomena and has recently been used to establish the presence of multiple intermediates during the folding of a model polypeptide, polyproline. These observations, however, are made on gas-phase structures. Capillary electrophoresis (CE) is a complementary solution-phase technique, also based on the separation of charged species as a function of size and charge. Here, both ion mobility and capillary electrophoresis are used to follow the folding transition of a 13-mer polyproline peptide from the all-cis polyproline I (PPI) conformation to the all-trans polyproline II (PPII) conformation upon immersion in aqueous solvent...
November 4, 2016: Analytical Chemistry
Rhett L Martineau, Sarah Anne Murray, Shufang Ci, Weimin Gao, Shih-Hui Chao, Deirdre R Meldrum
This work describes an enhancement to the loop-mediated isothermal amplification (LAMP) reaction which results in improved performance. Enhancement is achieved by adding a new set of primers to conventional LAMP reactions. These primers are termed 'Swarm primers' based on their relatively high concentration and their ability to create new amplicons despite the theoretical lack of single-stranded annealing sites. The primers target a region upstream of the FIP/BIP primer recognition sequences on opposite strands, substantially overlapping F1/B1 sites...
November 4, 2016: Analytical Chemistry
Min Zhao, Anyi Chen, Dan Huang, Ying Zhuo, Yaqin Chai, Ruo Yuan
Cu nanoclusters (Cu NCs), emerged as a new class of non-toxic, economic, and excellent phosphor and catalyst, have attracted increasing interest for a wide variety of promising applications in bio-labeling and bio-catalysis. However, the electrochemiluminescence (ECL) behavior of Cu NCs has never reported in previous works. Here, anodic and blue ECL emission of Cu NCs is observed for the first time with the efficient coreactant of hydrazine (HZ), and the possible luminescence mechanism of Cu NCs/HZ ECL system is studied in detail...
November 4, 2016: Analytical Chemistry
Jorge Regueiro, Noelia Negreira, Marc H G Berntssen
Ion mobility spectrometry allows for the measurement of the collision cross section (CCS), which provides information about the shape of an ionic molecule in the gas phase. Although the hyphenation of traveling-wave ion mobility spectrometry (TWIMS) with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS) has been mainly used for structural elucidation purposes, its potential for fast screening of small molecules in complex samples has not yet been thoroughly evaluated. The current work explores the capabilities of ultrahigh-performance liquid chromatography (UHPLC) coupled to a new design TWIMS-QTOFMS for the screening and identification of a large set of pesticides in complex salmon feed matrices...
November 4, 2016: Analytical Chemistry
Hui Xie, Yu-Tao Li, Yong-Min Lei, Yan-Ling Liu, Meng-Meng Xiao, Chuan Gao, Dai-Wen Pang, Wei-Hua Huang, Zhi-Yong Zhang, Guo-Jun Zhang
An ultrasensitive and highly efficient assay for real-time monitoring of nitric oxide (NO) at single-cell level based on a reduced graphene oxide (RGO) and iron-porphyrin-functionalized graphene (FGPCs) field-effect transistor (FET) biosensor is reported. A layer-to-layer assembly of RGO and FGPCs on a prefabricated FET sensor surface through π-π stacking interaction allowed superior electrical conductivity caused by RGO, and highly catalytic specificity induced by metalloporphyrin, ensuring the ultrasensitive and highly specific detection of NO...
November 4, 2016: Analytical Chemistry
Sujin Ahn, Peng Zhang, Hyunung Yu, Seungah Lee, Seong Ho Kang
Superlocalization of immunoplasmonic nanotags on antibody-bound gold-nanoislands (GNIs) along the x and y coordinates was determined using total internal reflection scattering-based super-resolution microscopy (TIRS-SRM) at subdiffraction limit resolution. Individual immunoplasmonic nanotags (20 nm silver nanoparticles) and 100 nm GNIs were selectively acquired in the evanescent field layer by wavelength-dependent plasmonic scattering using two illumination lasers (405 and 635 nm, respectively). α-Fetoprotein (AFP), a liver cancer-related model protein, was immobilized as a target molecule on the GNI arrays...
November 4, 2016: Analytical Chemistry
Tianran Lin, Yarong Wu, Zhihong Li, Zhiping Song, Liangqia Guo, Fengfu Fu
Colorimetric detection of biogenic amines, well-known indicators of food spoilage, plays an important role for monitoring of food safety. However, common colorimetric sensors for biogenic amines suffer from low color resolution or complicated design and intricate output for the end-users. Herein, we explored a simple but effective strategy for visual monitoring of biogenic amines with multiple color change based on hydrolysis-induced silver metallization reaction to tune the localized surface plasmon resonance (LSPR) adsorption of Au nanorods (NRs)...
November 4, 2016: Analytical Chemistry
Emilia Witkowska Nery, Magdalena Kundys, Paulina S Jeleń, Martin Jönsson-Niedziółka
As diabetes is considered one of the biggest health care challenges of the coming decades substantial effort is being made to develop novel glucose monitoring systems, this includes thousands of articles which are being published every year. To the question in the title, we answer an unequivocal "yes" but maybe not necessarily in the areas where most of the published research is focused.
November 4, 2016: Analytical Chemistry
Eun Ji Park, Dong Hee Na
The separation mechanism of PEGylated peptides in reversed-phase high-performance liquid chromatography (RP-HPLC) is complex, because the PEGylated molecules exhibit physicochemical properties that are different from those of the parent molecules and have heterogeneous structure. Since most separation studies have focused on the hydrophobicity of the peptide relative to poly(ethylene glycol) (PEG), the role of PEG in the separation of PEGylated peptides on RP-HPLC is not clear. To elucidate the effect of the attached PEG on the retention of PEGylated peptides on RP-HPLC, the mono-PEGylated forms of collagen pentapeptide and octreotide were fractionated drop-by-drop from the outlet of the HPLC system and each drop was subjected to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)...
November 4, 2016: Analytical Chemistry
Lukáš Najdekr, David Friedecký, Ralf Tautenhahn, Tomáš Pluskal, Junhua Wang, Yingying Huang, Tomas Adam
Modern separation methods in conjunction with high resolution accurate mass (HRAM) spectrometry can provide an enormous number of features characterized by exact mass and chromatographic behavior. Higher mass resolving power usually requires longer scanning times, and thus fewer data points are acquired across the target peak. This could cause difficulties for quantification, feature detection and deconvolution. The aim of this work was to describe the influence of mass spectrometry resolving power on profiling metabolomics experiments...
November 3, 2016: Analytical Chemistry
Bryan S Reatini, Elliot Ensink, Brian Liau, Jessica Y Sinha, Thomas W Powers, Katie Partyka, Marshall Bern, Randall E Brand, Pauline Mary Rudd, Doron Kletter, Richard R Drake, Brian B Haab
Glycans are critical to protein biology and are useful as disease biomarkers. Many studies of glycans rely on clinical specimens, but the low amount of sample available for some specimens limits the experimental options. Here we present a method to obtain information about protein glycosylation using a minimal amount of protein. We treat proteins that were captured or directly spotted in small microarrays (2.2 x 2.2 mm) with exoglycosidases to successively expose underlying features, and then we probe the native or exposed features using a panel of lectins or glycan-binding reagents...
November 3, 2016: Analytical Chemistry
Rui Chen, Kai Cheng, Zhibin Ning, Daniel Figeys
We report a new approach called NGlycoReduction that generates an oligomannosylated N-glycopeptidome by enzymatically removing sugars outside the N-glycopeptide pentasaccharide core with exoglycosidases. This approach is based on our discovery that the fragmentation of glycopeptides is glycan-structure dependent and glycans with core mannose structures overwhelmingly lead to the generation of Y1 ions when subjected to MS/MS in mass spectrometry. Oligomannosylated glycopeptidome produced by NGlycoReduction can be mixed with the intact N-glycopeptidome and analyzed by HPLC-ESI-MS together to enable the identification of peptide sequence, glycosylation site and the structure of intact glycopeptides...
November 3, 2016: Analytical Chemistry
Lisa Eiden, Cameron Yamanishi, Shuichi Takayama, John F Dishinger
Multiplex immunoassays are rapidly increasing in popularity due to the offered advantages of increased throughput and decreased sample volume requirements. However, a major weakness inherent to multiplex enzyme-linked immunosorbent assays (ELISA) is generation of false signals through reagent-driven crosstalk. Typically, multiplex platforms necessitate bath application of antibody cocktails, increasing probability of non-specific antibody binding, especially when multiplexing large numbers of analytes. Aqueous two phase systems (ATPS) exploiting the phase-separating polymers poly(ethylene) glycol (PEG) and dextran (DEX) have been used to compartmentalize antibodies and prevent crosstalk in multliplex, plate-based ELISA...
November 3, 2016: Analytical Chemistry
Xiang Li, Jonathan T Cox, Weiliang Huang, Maureen A Kane, Keqi Tang, Charles J Bieberich
Despite recent advancements in large-scale phospho-proteomics, methods to quantify kinase-specific phosphorylation stoichiometry of protein substrates are lacking. We developed a method to quantify kinase-specific phosphorylation stoichiometry by combining the reverse in-gel kinase assay (RIKA) with high resolution LC-MS. Beginning with predetermined ratios of phosphorylated to non-phosphorylated Protein Kinase CK2 (CK2) substrate molecules, we employed 18O-ATP as the phosphate donor in a RIKA, then quantified the ratio of 18O- versus 16O-labeled tryptic phosphopeptide using high mass accuracy MS...
November 3, 2016: Analytical Chemistry
Yanli Lei, Jinlu Tang, Hui Shi, Xiaosheng Ye, Xiaoxiao He, Fengzhou Xu, Lv'an Yan, Zhenzhen Qiao, Kemin Wang
DNA-based activatable theranostic nanoprobes are still unmet for in vivo applications. Here, by utilizing the "induced-fit effect", a smart split aptamer-based activatable theranostic probe (SATP) was first designed as "nanodoctor" for cancer-activated in vivo imaging and in situ drug release. The SATP assembled with quenched fluorescence and stable drug loading in its free state. Once binding to target proteins on cell surface, the SATP disassembled due to recognition-triggered reassembly of split aptamers with activated signals and freed drugs...
November 3, 2016: Analytical Chemistry
Vladislav L Lychagov, Anton A Shemetov, Ralph Jimenez, Vladislav V Verkhusha
We have developed a microfluidic flow cytometry system to screen reversibly photoswitchable fluorescent proteins for contrast and stability of reversible photoconversion between high and low fluorescent states. A two-color array of 20 excitation and deactivation beams generated with diffractive optics was combined with a serpentine microfluidic channel geometry designed to provide five cycles of photoswitching with real-time calculation of photoconversion fluorescence contrast. The characteristics of photoswitching in-flow as a function of excitation and deactivation beam fluence, flow speed and protein concentration were studied with droplets of the bacterial phytochrome DrBphP from Deinococcus radiodurans, which is weakly fluorescent in the near-infrared spectral range...
November 3, 2016: Analytical Chemistry
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