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Analytical Chemistry

Yue Cai, Zhengyu Huang, Michelle Hoi Ching Cheung, Vincent Motto-Ros, Po-Chun Chu, Yuanwei Wang, Haoyi Zhong, Ronald Yuen, Kelvin Sze-Yin Leung, Judy T S Lum, Sut Kam Phoebe Ho, Nai Ho H Cheung
Chemical analysis of Chinese black ink on xuan paper is useful for the authentication of Asian artwork. The analysis has to be non-destructive and has to accommodate artworks of all sizes. We apply three analytical techniques, ArF laser-induced plume fluorescence, Fourier transform infra-red (FTIR) spectroscopy and portable X-ray fluorescence (pXRF) to analyze five commercial Chinese black inks on two kinds of xuan paper. The FTIR signal is found to be interfered by the substrate which is inevitable because the pigments diffuse extensively into the xuan fiber network...
October 18, 2016: Analytical Chemistry
Dongqing Kong, Sai Bi, Zonghua Wang, Jianfei Xia, Feifei Zhang
In this work, an in situ growth protocol is introduced to fabricate three-dimensional graphene films (3D GFs) on gold substrates, which are successfully utilized as working electrode for electrochemical detection of nucleic acid (microRNA) and protein (lysozyme) based on a signal-on sensing mechanism. To realize the bridge between the gold substrate and graphene film, a monolayer of 4-aminothiophenol is self-assembled on the substrate, which is then served as connectors for the growth of 3D GFs on the gold substrate by the hydrothermal reduction (HR) technique...
October 18, 2016: Analytical Chemistry
Guang-Yao Zhang, Yu-Hong Zhuang, Dan Shan, Guo-Fang Su, Serge Cosnier, Xueji Zhang
A simple and rapid photoelectrochemical (PEC) sensor is developed for the label-free detection of a phosphoprotein (α-casein) based on a zirconium based porphyrinic metal-organic framework (MOF), PCN-222, which exhibits an enhanced photocurrent response towards dopamine under the O2-saturated aqueous media. In this work, in terms of PEC measurements and cyclic voltammetry, the PEC behaviors of PCN-222 in aqueous media were thoroughly investigated for the first time. Additionally, in the virtue of the steric hindrance effect from the coordination of the phosphate groups and inorganic Zr-O clusters as binding sites in PCN-222, this biosensor shows high sensitivity for detecting α-casein and the limit of detection (LOD) is estimated to be 0...
October 18, 2016: Analytical Chemistry
Rong-Wei Si, Yuan Yang, Yangyang Yu, Song Han, Chun-Lian Zhang, De-Zhen Sun, Dan-Dan Zhai, Xiang Liu, Yang-Chun Yong
A whole-cell bioelectrochemical biosensing system for amperometric detection of riboflavin was developed. A "bioelectrochemical wire" (BW) consists of riboflavin and cytochrome C between S. oneidensis MR-1 and electrode was characterized. Typically, strong electrochemical response was observed when riboflavin was added to reinforce this BW. Impressively, the electrochemical response of riboflavin with this BW was over 200 times higher than that without bacteria. Uniquely, this electron rewiring process enabled the development of a biosensing system for amperometric detection of riboflavin...
October 18, 2016: Analytical Chemistry
Yiru Wang, Zhengpeng Qin, David R Boulware, Bobbi S Pritt, Lynne M Sloan, Iveth J González, David Bell, Roxanne R Rees-Channer, Peter Chiodini, Warren C W Chan, John C Bischof
There is an increasing need for highly sensitive and quantitative diagnostics at the point-of-care. The lateral flow immunoassay (LFA) is one of the most widely used point-of-care diagnostic tests; however, LFAs generally suffers from low sensitivity and lack of quantification. To overcome these limitations, thermal contrast amplification (TCA) is a new method that is based on the laser excitation of gold nanoparticles (GNP), the most commonly used visual signature, to evoke a thermal signature. To facilitate the clinical translation of the TCA technology, we present the development of a TCA reader, a platform technology that significantly improves the limit of detection and provides quantification of disease antigens in LFAs...
October 17, 2016: Analytical Chemistry
Valentina Di Gialleonardo, Sui Seng Tee, Hannah N Aldeborgh, Vesselin Z Miloushev, Lidia S Cunha, George D Sukenick, Kayvan R Keshari
Nuclear magnetic resonance (NMR) spectroscopy is used in metabolomics to perform quantitative profiling of low-molecular weight compounds from biological specimens. The measurement of endogenous metabolites using NMR can identify new metabolic biomarkers in physiological and pathological conditions, and assess treatment response. In this study we present a rapid approach to indirectly quantify 13C enriched molecules using one-dimensional (1D) 1H NMR. We demonstrate this approach using isotopically labeled [1,6-13C]glucose and in 4 different cell lines...
October 17, 2016: Analytical Chemistry
Jaclyn A Adkins, Eka Noviana, Charles S Henry
An electrochemical paper-based analytical device (ePAD) was developed for quasi-steady flow detection at microwire electrodes, for the first time. The device implements a fan shaped geometry connected to an analysis channel whereby solution is pulled from an inlet, through a channel, and into the steadily increasing capillary network of the fan. The network counteracts the decrease in solution flow rate associated with increasing viscosity within the channel, generating quasi-steady flow within the analysis channel...
October 17, 2016: Analytical Chemistry
Gao-Chao Fan, Xiao-Mei Shi, Jianrong Zhang, Jun-Jie Zhu
Generally, photoanode-based photoelectrochemical immunoassay possesses obvious photocurrent response and lower detection limit for ideal sample detection, but it has the inherent imperfection of poor anti-interference capability for real sample detection. Photocathode-based immunoassay can well avoid the intrinsic drawback of photoanode-based immunoassay, but it has low photocurrent response resulting in less good sensitivity. Herein, a promising new cathode photoelectrochemical immunosensing platform integrating photocathode with photoanode was reported for accurate and sensitive detection of biomarkers...
October 17, 2016: Analytical Chemistry
Carlos A Teixeira, Gabriela Furlan Giordano, Maisa B Beltrame, Luis Carlos Silveira Vieira, Angelo Luiz Gobbi, Renato Sousa Lima
The contamination, passivation, or fouling of the detection electrodes is a serious problem undermining the analytical performance of electroanalytical devices. The methods to regenerate the electrochemical activity of the solid electrodes involve mechanical, physical, or chemical surface treatments that usually add operational time, complexity, chemicals, and further instrumental re-quirements to the analysis. In this paper, we describe for the first time a reproducible method for renewing solid electrodes when-ever their morphology or composition are non-specifically changed without any surface treatment...
October 17, 2016: Analytical Chemistry
Gongyu Li, Siming Yuan, Yang Pan, Yangzhong Liu, Guangming Huang
The identification of endogenous proteins as well as their binding to metal ions in living cells is determined by combining pulsed electrophoretic separations with nanoelectrospray ionization followed by mass spectrometric detection. This approach avoids problems resulting from the complicated cellular environment. In this manner we demonstrate the rapid identification (300 ms or less) of intact proteins from living E. coli cells including the complexation of calmodulin with calcium ion. The latter showed different binding states from those observed in in-vitro studies...
October 17, 2016: Analytical Chemistry
Christopher Batchelor-McAuley, Christopher A Little, Stanislav V Sokolov, Enno Kätelhön, Giorgia Zampardi, Richard G Compton
The lipid soluble fluorophore Nile Red (9-diethylamino-5-benzo[α]phenoxazinone) is used to fluorescently and electrochemically label an organic-in-water emulsion, where the organic phase is an ionic liquid [P6,6,6,14][FAP]/toluene mixture. The optical detection of the individual droplets is enabled facilitating the in-situ tracking and sizing of the suspended particles (average diameter = 530 nm, interquartile range = 180 nm). Through the use of a combined thin-layer optical/electrochemical cell, the irreversible accumulation of the droplets at an optically opaque carbon fibre electrode (diameter ~ 7...
October 17, 2016: Analytical Chemistry
Carola Schultz, Sven Vedder, Martin Winter, Sascha Nowak
The development of a novel high performance liquid chromatography (HPLC) method hyphenated to an ion-trap time-of-flight mass spectrometer (IT-TOF-MS) for the separation and identification of constituents from common organic carbonate solvent-based electrolyte systems in lithium ion batteries (LIBs) is presented in this work. The method development was developed for the qualitative structural elucidation of electrolyte main constituents with a special focus on the aging products of these components. The determination of their limits of detection was performed as well...
October 17, 2016: Analytical Chemistry
Lucia Geis-Asteggiante, Suzanne Ostrand-Rosenberg, Catherine Fenselau, Nathan J Edwards
Spectral counting is a straightforward label-free quantitation strategy used in bottom-up proteomics workflows. The application of spectral counting in label-free top-down proteomics workflows can be similarly straightforward, but has not been applied as widely as quantitation by chromatographic peak areas or peak intensities. In this study, we evaluate spectral counting for quantitative comparisons in label-free top-down proteomics workflows by comparison with chromatographic peak areas and intensities. We tested these quantitation approaches by spiking standard proteins into a complex protein background and comparing relative quantitation by spectral counts with normalized chromatographic peak areas and peak intensities from deconvoluted extracted ion chromatograms of the spiked proteins...
October 17, 2016: Analytical Chemistry
Yong Li, Xu Wang, Jie Yang, Xilei Xie, Mengmeng Li, Jinye Niu, Lili Tong, Bo Tang
Carbon monoxide (CO), a crucial gas message molecule, plays an important role in the regulation of physiological and pathological process. Hypoxia-induced CO is involved in modulating various cellular activities, including signal transduction, proliferation, and apoptosis. However, tracking CO fluctuation in the hypoxic cells is still a challenge due to lack of straight forward, visualized and non-invasive tools. In this work, based on metal palladium-catalyzed reaction, we present the rational design, synthesis and biological utility of an azobenzene-cyclopalladium-based fluorescent probe, ACP-2, for CO monitoring...
October 17, 2016: Analytical Chemistry
Phillip Walsh, Manuel Garbalena, Kevin A Schug
A time interval deconvolution (TID) method was devised to integrate a gas chromatography - vacuum ultraviolet (GC-VUV) data set in order to provide bulk characterization and speciation of finished gasoline samples. The method was demonstrated using a commercially available standard and tested on a series of ASTM gasoline proficiency samples. Very good correlation (R2 ~0.97-0.99) between GC-VUV and measurements using various ASTM methods was achieved. A key advantage of the TID method applied to GC-VUV datasets is that a large number of coelution events can be tolerated, resulting in significantly easier and faster separations, approximately 30 minutes in the case of gasoline...
October 17, 2016: Analytical Chemistry
Andrea Buffa, Yigal Erel, Daniel Mandler
A flow-through electrode made of a carbon nanotubes (CNT) film deposited on a polytetrafluoroethylene (PTFE) membrane was assembled and employed for the determination of low concentration of copper as a model system by linear sweep anodic stripping voltammetry (LSASV). CNT films with areal mass ranging from 0.12 to 0.72 mg cm-2 were characterized by measurement of sheet resistance, water permeation flux and capacitance. Moreover, CNT with two different sizes and PTFE membrane with two different pore diameters (0...
October 17, 2016: Analytical Chemistry
Su-Dai Ma, Yong-Lei Chen, Jie Feng, Juan-Juan Liu, Xian-Wei Zuo, Xing-Guo Chen
A sensitive and selective fluorescence "turn-off" sensor to detect heparin using water-soluble silicon nanoparticles (Si NPs) was developed for the first time. The Si NPs were synthesized by a simple one-step procedure, which did not need high-temperature and complex modification. The as-prepared Si NPs featured strong fluorescence, favorable biocompatibility, and robust photo- and pH stability. Significantly, the Si NPs were induced to assemble or aggregate via hydrogen bonding, which resulted in the fluorescence of Si NPs quenched...
October 17, 2016: Analytical Chemistry
Fengli Qu, Minghui Yang, Avraham Rasooly
The protease BACE1 (the β-site amyloid precursor protein cleaving enzyme 1) catalyzes the first step in the synthesis of β-amyloids (Aβ), peptides that accumulate in the brain in Alzheimer's disease (AD). Measurement of BACE1 activity is important for the development of BACE1 inhibitors to slow or stop AD. To measure BACE1 cleavage of the electrode-immobilized substrate peptide, we developed a redox-generating hydroxyapatite (HAP) probe which generates electrochemical current by reaction of the nanoparticle with molybdate (MoO4(2-))...
October 17, 2016: Analytical Chemistry
Julianne Cook Botelho, Ashley Ribera, Hans C Cooper, Hubert W Vesper
The inaccuracy of 17- βestradiol (E2) measurements affects its use as a biomarker in patient care and research. Clinical and research communities called for accurate and standardized E2 measurements. Reference Measurement Procedures (RMPs), part of the CDC Hormone Standardization Program (HoSt), are essential in addressing this need and ensuring that methods are accurate and comparable across testing systems, laboratories, and over time. A candidate RMP (cRMP) was developed for the measurement of total E2 in serum using liquid chromatography tandem mass spectrometry (LC-MS/MS) without derivatization...
October 16, 2016: Analytical Chemistry
Jeniffer V Quijada, Nicholas Daniel Schmitt, Joseph P Salisbury, Jared R Auclair, Jeffrey Neil Agar
Stable isotope labeling techniques for quantitative top-down proteomics face unique challenges. These include unpre-dictable mass shifts following isotope labeling, which impedes analysis of unknown proteins and complex mixtures; and exponen-tially greater susceptibility to incomplete isotope incorporation, manifesting as broadening of labeled intact protein peaks. Like pop-ular bottom-up isotope labeling techniques, most top-down labeling methods are restricted to defined media/feed as well as amino acid auxotrophic organisms...
October 15, 2016: Analytical Chemistry
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