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Analytical Chemistry

Aruna S Prakash, Abdulbaset M F Kabli, Neil J Bulleid, Richard Burchmore
Cysteine redox state has been identified as one of the key biological influences behind protein structure and/or function. Altered protein redox state has been shown to cause significant physiological changes and can leave proteins with changed sensitivity to oxidative stress. Protein redox state changes are recognized as an important mediator of disease, cellular abnormalities or environmental changes and therefore their characterization is of interest. Isotopic or isobaric labeling followed by sample multiplexing and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) allows relative comparison of protein expression levels or of protein redox state between several samples...
November 19, 2018: Analytical Chemistry
G Ij Salentijn, M Grajewski, E Verpoorte
This paper focuses on one of the most commonly encountered materials in our society, namely paper. Paper is an inherently complex material, yet its use provides for chemical analysis approaches that are elegant in their simplicity of execution. In the first half of the previous century, paper in scientific research was used mainly for filtration and chromatographic separation. While its use decreased with the rise of modern elution chromatography, paper remains a versatile substrate for low-cost analytical tests...
November 19, 2018: Analytical Chemistry
Shuo Wu, Wenjuan Tu, Yanqiu Zhao, Xiuyun Wang, Jie Song, Xinlan Yang
A ruthenium(II) bipyridyl derivative photoelectrochemical probe, Ru-1, is synthesized and coupled with TiO2 nanoparticles (Ru-1/TiO2) for the specific recognition and highly sensitive PEC detection of Hg2+ in a series of biofluids. The probe is designed with a chromophore, a thiocyanate recognition unit, a π-conjugated photoelectron transfer pathway, and a phosphonate anchor. TiO2 nanoparticles with strong affinity to phosphonate and suitable conduction band energy are used as intermediate layers to increase the Ru-1 adsorption amount and amplify the photocurrent response...
November 19, 2018: Analytical Chemistry
Liang Hu, Mansi Anand, Svetlana M Krylova, Burton B Yang, Stanley K Liu, George M Yousef, Sergey N Krylov
Direct quantitative analysis of multiple miRNAs (DQAMmiR) is a hybridization-based assay in which the excess of the DNA hybridization probes is separated from the miRNA-probe hybrids and the hybrids are separated from each other in gel-free capillary electrophoresis (CE) using two types of mobility shifters: single-strand DNA binding protein (SSB) added to the CE run buffer and peptide drag tags conjugated with the probes. Here we introduce the second-generation DQAMmiR which utilizes peptide nucleic acid (PNA) rather than DNA hybridization probes and requires no SSB in the CE run buffer...
November 19, 2018: Analytical Chemistry
Jun Dai, Yingru Zhang
Previously, we reported a new online capillary isoelectric focusing-mass spectrometry (CIEF-MS) method for intact monoclonal antibody (mAb) charge variant analysis using an electrokinetically pumped sheath-flow nanospray ion source on a time-of-flight (TOF) MS with a pressure-assisted chemical mobilization. The direct online CIEF-MS method exhibited excellent charge variants resolution conforming to those of imaged CIEF-UV (iCIEF-UV). However, for complex mAbs, CIEF-MS spectra of the intact charge variant peaks may be overly convoluted to be effectively interpreted...
November 19, 2018: Analytical Chemistry
Sebastian Patrick Schwaminger, Benedikt Begovic, Lukas Schick, Nur Aisyah Jumani, Markus Wilhelm Brammen, Paula Fraga García, Sonja Berensmeier
Potential-controlled tensiometry is a voltage-induced method which enables measuring the contact angle between a powder bed and a liquid medium through the capillary rise method. This analytical tool provides a fine-grained technique for understanding wetting behavior of powders as well as solid surfaces in connection with the application of an electrical potential. In this work, the powder bed was brought into contact with an aluminum rod connected to a portable light-weight DAC-module (digital to analogue converter) powered by a lithium-polymer battery (LiPo)...
November 19, 2018: Analytical Chemistry
Gui-Xiang Huang, Jin-Yan Si, Chen Qian, Wei-Kang Wang, Shu-Chuan Mei, Chu-Ya Wang, Han-Qing Yu
Recently, peroxymonosulfate (PMS)-based advanced oxidation processes have exhibited broad application prospects in the field of environment. Accordingly, a simple, rapid and ultrasensitive method is highly desired for the specific recognition and accurate quantification of PMS in various aqueous solutions. In this work, SO4•--induced aromatic hydroxylation was explored, and based on that, for the first time, a novel fluorescence method was developed for the PMS determination using Co2+ as a PMS activator and benzoic acid (BA) as a chemical probe...
November 19, 2018: Analytical Chemistry
Yunshan Fan, Rui Hao, Chu Han, Bo Zhang
We report the use of a Pt bipolar electrochemical nanocell and fluorescence to detect single redox molecules. A Pt nanocell is formed by depositing a Pt particle at a nanopipet orifice which separates the inside pipet volume from the bulk solution. Highly fluorescent resorufin molecules are generated on the inner Pt surface and optically detected and counted due to unique properties of the nanocell. First, the pipet is horizontally positioned on a microscope allowing one to examine a 6-μm distance from the electrode/solution interface...
November 19, 2018: Analytical Chemistry
Young Joon Sung, Ho Seok Kwak, Min Eui Hong, Hong Il Choi, Sang Jun Sim
Microalgae have been spotlighted as a renewable energy source to produce biofuels from CO2 by photosynthesis. However, their innate inefficiency of CO2 conversion using light energy has been a challenge to the commercialization of algae-based biofuel production. Photosynthetic organisms have evolved behavioral responses, including phototaxis and chemotaxis, to find optimal conditions for capturing light energy and inorganic carbon (Ci) sources for photosynthesis. In this context, investigation of phototaxis and chemotaxis to HCO3 - , the predominant form of Ci in neutral aqueous solutions, is necessary to understand the physiological role of tactic responses in photosynthesis...
November 19, 2018: Analytical Chemistry
Mohammad Pousti, Maxime Joly, Patrice Roberge, Mehran Abbaszadeh Amirdehi, Andre Begin-Drolet, Jesse Greener
A fully automated linear scanning attenuated total reflection (ATR) accessory is presented for Fourier transform infrared (FTIR) spectrosco-py. The approach is based on the accurate displacement of a multi-bounce ATR crystal relative to a stationary infrared beam. To ensure accu-rate positioning and to provide a second sample characterization mode, a custom-built microscope was integrated into the system and the computerized work flow. Custom software includes automated control and measurement routines with a straightforward user interface for selecting parameters and monitoring experimental progress...
November 18, 2018: Analytical Chemistry
Dominik Braun, Chibundu N Ezekiel, Wilfred A Abia, Lukas Wisgrill, Gisela H Degen, Paul Craig Turner, Doris Marko, Benedikt Warth
Infants are particularly susceptible towards the toxic effects of food contaminants including mycotoxins. However, multi-mycotoxin exposure assessment in breast milk has received very limited attention so far, resulting in a poor understanding of co-exposures during early-life. Here, we present the development and application of a highly sensitive, specific and quantitative assay assessing up to 28 mycotoxins including regulated (aflatoxins, ochratoxin A, deoxynivalenol, zearalenone) and emerging mycotoxins as well as key metabolites by LC-MS/MS...
November 18, 2018: Analytical Chemistry
Charles M Nichols, James N Dodds, Bailey Rose, Jaqueline A Picache, Caleb B Morris, Simona G Codreanu, Jody C May, Stacy D Sherrod, John A McLean
In this work we have established a collision cross section (CCS) library of primary metabolites based on analytical standards in the Mass Spectrometry Metabolite Library of Standards (MSMLS) using a commercially available ion mobility-mass spectrometer (IM-MS). From the 554 unique compounds in the MSMLS plate library, we obtained a total of 1246 CCS measurements over a wide range of biochemical classes and adduct types. Resulting data analysis demonstrated that the curated CCS library provides broad molecular coverage of metabolic pathways and highlights intrinsic mass-mobility relationships for specific metabolite super classes...
November 18, 2018: Analytical Chemistry
Urban Wünsch, Evrim Acar, Boris Peter Koch, Kathleen Murphy, Philippe Schmitt-Kopplin, Colin Andrew Stedmon
Investigating the biogeochemistry of dissolved organic matter (DOM) requires the synthesis of data from several complementary analytical techniques. In contrast to subjective post-hoc correlation analysis, a robust integration requires data fusion, capable of simultaneously decomposing data from multiple instruments while identifying linked and unrelated signals. Here, Advanced Coupled Matrix and Tensor Factorization (ACMTF) was used to identify the molecular fingerprint of DOM fluorescence fractions in Arctic fjords...
November 18, 2018: Analytical Chemistry
Igor Telegeiev, Oumaima Thili, Adrien Lanel, Philippe Bazin, Yoann Levaque, Christian Fernandez, Mohamad El-Roz
Various catalytic and photocatalytic reactions in the liquid phase give rise to gas products. Therefore, the identification and quantification of these products are of high importance and even essential for some reactions. In this communication, a new in situ FTIR reactor is designed and used for analyzing the gas headspace of a (photo)catalytic reaction in solution. It allows the identification and quantification of the gas products of a liquid reaction under operating conditions and in real time. The new reactor has been tested in three representative photocatalytic reactions widely studied as model reactions in the liquid phase, i...
November 18, 2018: Analytical Chemistry
Jamie P Do, Kevin J Cao, Sylvia Wei, Louise C Laurent, Mana M Parast, Jerry Yang
Preeclampsia (PE) is a hypertensive disorder of pregnancy and one of the leading contributors to both maternal and perinatal morbidity and mortality. Reliable diagnostic parameters unique to the disorder that accurately define and diagnose PE are currently unavailable. Recent studies have revealed that PE is accompanied by the accumulation of amyloidogenic deposits in the placenta and the presence of congophilic amyloid-like protein aggregates in the urine. Here, we evaluate the capability of an amyloid-targeting aryl cyano amide (ARCAM-1) fluorophore to identify PE patients from analysis of urine samples...
November 16, 2018: Analytical Chemistry
Liping Wang, Wei Li, Jin Sun, Su-Yun Zhang, Sheng Yang, Jingying Li, Juan Li, Huang-Hao Yang
On cell membrane surfaces, receptor protein dimers play a fundamental role in many signaling pathways, which are crucial for normal biological processes and cancer development. Efficient and sensitive analysis of receptor dimers in the native environment is highly desirable. Herein, we present a strategy for amplified imaging of receptor dimers in zebrafish and living cells, which relies on aptamer recognition and proximity-induced hybridization chain reaction. Taking advantages of specific aptamer recognition and enzyme-free signal amplification, this strategy is successfully applied to amplified visualize c-Met receptor dimers in the HGF-independent or -dependent manner...
November 16, 2018: Analytical Chemistry
Xinwei Liu, Jiexun Bu, Xiaoyu Zhou, Zheng Ouyang
Miniature mass spectrometers are of an increasing interest for in in-situ analyses and their coupling with the ambient ionization sources is a valid path for direct analysis of complex samples. In this study, a miniature mass spectrometer using discontinuous atmospheric pressure interface was developed with a dual-LIT (linear ion trap) configuration. The comprehensive scan modes were enabled for tandem mass spectrometry analysis, which are critical for high quality qualitative and quantitative analysis. A real-time pressure control was implemented to facilitate the ion transfer and collision induced dissociation (CID)...
November 16, 2018: Analytical Chemistry
Pengcheng Hu, Bolin Li, Chen Bai, Xu Li, Xiaolin Lu
With rapid development of materials science, on-demand techniques are highly needed with the capability to characterize materials in the micrometer and nanometer scales. In this article, we show that, by employing a prism geometry, total internal reflection (TIR) sum frequency generation (SFG) vibrational spectroscopy allows for characterizing mesoscopic materials with irregular or complex surfaces. Four representative examples were presented. First, we reveal that, mechanical grinding can subtly alter the surface molecular structures of original materials...
November 16, 2018: Analytical Chemistry
Shiwei Sun, Chuncui Huang, Yaojun Wang, Yaming Liu, Jingwei Zhang, Jinyu Zhou, Feng Gao, Fei Yang, Runsheng Chen, Barbara Mulloy, Wengang Chai, Yan Li, Dongbo Bu
Glycans play important roles in a variety of biological processes. Their activities are closely related to the fine details of their structures. Unlike the simple linear chains of proteins, branching is a unique feature of glycan structures, making their identification extremely challenging. Multistage mass spectrometry (MSn) has become the primary method for glycan structural identification. The major difficulty for MSn is the selection of fragment ions as precursors for the next stage of scanning. Widely-used strategies are either manual selection by experienced experts, which requires considerable expertise and time, or simply selecting the most intense peaks by which the product-ion spectrum generated may not be structurally informative and therefore fail to make the assignment...
November 16, 2018: Analytical Chemistry
Mengjie Li, Xin Tian, Wen-Bin Liang, Ruo Yuan, Yaqin Chai
Herein, an ultrasensitive photoelectrochemical (PEC) assay was developed for the monitoring of microRNA-141 (miRNA-141) based on poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th)/ CdTe quantum dots (CdTe QDs) sensitized structure as signal tag and the benzo-4-chloro-hexadienone (4-CD) precipitate as efficient quencher. PTB7-Th and CdTe QDs were successively modified on electrode surface to form a novel sensitized structure with eminent photovoltaic performances and surpassing film-forming ability...
November 16, 2018: Analytical Chemistry
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