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Analytical Chemistry

Tian A Qiu, Marco D Torelli, Ariane M Vartanian, Nathan B Rackstraw, Joseph T Buchman, Lisa M Jacob, Catherine J Murphy, Robert J Hamers, Christy L Haynes
Polyelectrolyte (PE) wrapping of colloidal nanoparticles (NPs) is a standard method to control NP surface chemistry and charge. Because excess polyelectrolytes are usually employed in the surface modification process, it is critical to evaluate different purification strategies to obtain a clean final product and thus avoid ambiguities in the source of effects on biological systems. In this work, 4 nm diameter gold nanoparticles (AuNPs) were wrapped with 15 kDa poly(allylamine hydrochloride) (PAH), and three purification strategies were applied: (a) diafiltration or either (b) one round or (c) two rounds of centrifugation...
January 10, 2017: Analytical Chemistry
Ana Flávia B Andrade, Samuel Kasahun Mamo, Jose Gonzalez-Rodriguez
The NBOMe derivatives are phenethylamines derived from the 2C class of hallucinogens. Only a few human pharmacologic studies have been conducted on these drugs, and several cases of intoxication and deaths have been reported. Presently, NBOMe are not a part of the routine drugs-of-abuse screening procedure for many police forces, and there are no rapid immunoassay screening tests that can detect the presence of those compounds. In this Article, the voltammetric behavior of 25B NBOMe and 25I NBOMe were investigated and their electroanalytical characteristics determined for the first time...
January 6, 2017: Analytical Chemistry
Xiaojun Liu, Aishan Zheng, Dongrui Luan, Xiaoting Wang, Fanpeng Kong, Lili Tong, Kehua Xu, Bo Tang
The discovery that hypobromous acid (HOBr) can regulate the activity of collagen IV has attracted great attention. However, HOBr as an important reactive small molecule has hardly ever been studied using a detection method suitable for organisms. Herein, a high-quantum-yield mitochondria-targeting near-infrared (NIR) fluorescent probe for HOBr, RhSN-mito, was designed. RhSN-mito was easily obtained by the Suzuki cross-coupling reaction. The test results show that RhSN-mito can rapidly respond to HOBr with ultrasensitivity and high selectivity...
January 5, 2017: Analytical Chemistry
Nianrong Sun, Jiawen Wang, Jizong Yao, Chun-Hui Deng
Hydrophilic interaction liquid chromatography (HILIC) is a significant enrichment strategy in glycoproteomics profiling. In this report, hydrophilic magnetic mesoporous silica materials (Fe3O4@mSiO2-IDA) were designed and synthesized as an outstanding enrichment platform for glycopeptide analysis. By taking advantage of their merits, such as large surface area, excellent hydrophilicity and unbiased affinity toward all types of glycopeptides, the Fe3O4@mSiO2-IDA nanomaterials were successfully applied to capture glycopeptides from complex samples...
January 4, 2017: Analytical Chemistry
Sanwang Li, Balázs Klencsár, Lieve Balcaen, Filip Cuyckens, Frederic Lynen, Frank Vanhaecke
Quantitative determination of the candidate drug molecule and its metabolites in biofluids and tissues is an inevitable step in the development of new pharmaceuticals. Due to the time-consuming and expensive nature of the current standard technique for quantitative metabolite profiling, i.e. radiolabelling followed by high-performance liquid chromatography (HPLC) with radiodetection, the development of alternative methodologies is of great interest. In this work, a simple, fast, sensitive and accurate method for the quantitative metabolite profiling of an amino group containing drug (levothyroxine) and its metabolites in human plasma, based on pre-column derivatization followed by HPLC-inductively coupled plasma-mass spectrometry (ICP-MS), was developed and validated...
January 4, 2017: Analytical Chemistry
Muhammad Khan, Santosh K Misra, Zhen Wang, Enrique A Daza, Aaron Schwartz-Duval, Joseph Kus, Debanjan Pan, Dipanjan Pan
Cortisol has been identified as a biomarker in saliva to monitor psychological stress. In this work, we report label-free paper-based electrical biosensor chip to quantify salivary cortisol at a point-of-care (POC) level. A high specificity of the sensor chip to detect cortisol with detection limit of 3 pg/mL was achieved by conjugating anti-cortisol antibody (anti-CAB) on top of gold (Au) microelectrodes using 3,3'-Dithiodipropionic acid di(N-hydroxysuccinimide ester (DTSP) - as self-assembled monolayer (SAM) agent...
January 4, 2017: Analytical Chemistry
Panteleimon G Takis, Leonardo Tenori, Enrico Ravera, Claudio Luchinat
In this letter we propose an alternative, effective protocol for metabolomic characterization of biofluids based on their gelification and subsequent application of high resolution magic angle spinning (HRMAS) (1)H nuclear magnetic resonance (NMR). The sample handling is very rapid and reproducible, and much less than 40 μl of neat urine are needed to obtain a sample. Our results indicate that the HRMAS spectra of gelified urine encompass all metabolites in the NMR fingerprint, as observed by solution NMR...
January 3, 2017: Analytical Chemistry
Jan Christopher Guder, Thorben Schramm, Timur Sander, Hannes Link
Cellular metabolite concentrations hold information on the function and regulation of metabolic networks. However, current methods to measure metabolites are either low-throughput or not quantitative. Here we optimized conditions for liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) for quantitative measurements of primary metabolites in 2-minute runs. In addition, we tested hundreds of multiple reaction monitoring (MRM) assays for isotope ratio mass spectrometry of most metabolites in amino acid, nucleotide, cofactor and central metabolism...
January 3, 2017: Analytical Chemistry
Janine Elliott, Jonathon Duay, Olja Simoska, Jason B Shear, Keith J Stevenson
Transparent carbon ultramicroelectrode arrays (T-CUAs) were made using a previously reported facile fabrication method (Duay et al. Anal. Chem. 2015, 87, 10109). Two modifications introduced to the T-CUAs were examined for their analytical response to nitric oxide (NO(•)). The first modification was the application of a cellulose acetate (CA) gas permeable membrane. Its selectivity to NO(•) was extensively characterized via chronoamperometry, electrochemical impedance spectroscopy (EIS), and atomic force microscopy (AFM)...
January 3, 2017: Analytical Chemistry
Juan Qiao, Hong Ding, Qianrong Liu, Rongyue Zhang, Li Qi
A microfluidic droplet synthesis approach for preparation of poly N-isopropylacrylamide protected gold nano particles (PNIPAm@AuNPs) was presented here. Well dispersed PNIPAm@AuNPs could be generated within 8 min. Based on the aggregation-induced UV-vis adsorption intensity increasing mechanism, the PNIPAm@AuNPs based colorimetric probe displayed high sensitivity and good selectivity for sensing copper ions. A linear calibration of relative UV-vis adsorption intensity increasing versus copper ions concentration was obtained within 5...
December 30, 2016: Analytical Chemistry
Jin-Liang Ma, Bin-Cheng Yin, Xin Wu, Bang-Ce Ye
We present a new glucose oxidase (GOx)-mediated strategy for detecting glucose based on carbon nanodots supported on silver nanoparticles (C-dots/AgNPs) as nanocomplexes. The strategy involves three processes: quenching of C-dots' fluorescence by AgNPs, production of H2O2 from GOx-catalyzed oxidation of glucose, and H2O2-induced etching of AgNPs. In the C-dots/AgNPs complex, AgNPs act as a "nanoquencher" to decrease C-dots fluorescence by surface plasmon-enhanced energy transfer (SPEET) from C-dots (donor) to AgNPs (acceptor)...
December 30, 2016: Analytical Chemistry
James J Galligan, Philip J Kingsley, Orrette R Wauchope, Michelle M Mitchener, Jeannie M Camarillo, James A Wepy, Peter S Harris, Kristofer S Fritz, Lawrence J Marnett
Post-translational modifications (PTMs) affect protein function, localization, and stability, yet very little is known about the ratios of these modifications. Here, we describe a novel method to quantitate and assess the relative stoichiometry of Lys and Arg modifications (QuARKMod) in complex biological settings. We demonstrate the versatility of this platform in monitoring recombinant protein modification of peptide substrates, PTMs of individual histones, and the relative abundance of these PTMs as a function of subcellular location...
December 30, 2016: Analytical Chemistry
Mark T Agasid, Troy J Comi, S Scott Saavedra, Craig A Aspinwall
The binding of a target analyte to an ion channel (IC), which is readily detected electrochemically in a label-free manner with single-molecule selectivity and specificity, has generated widespread interest in using natural and engineered ICs as transducers in biosensing platforms. To date, the majority of developments in IC-functionalized sensing have focused on IC selectivity or sensitivity or development of suitable membrane environments and aperture geometries. Comparatively little work has addressed analytical performance criteria, particularly criteria required for temporal measurements of dynamic processes...
December 30, 2016: Analytical Chemistry
Eunkyoung Kim, Thomas E Winkler, Christopher Kitchen, Mijeong Kang, George Banis, William E Bentley, Deanna L Kelly, Reza Ghodssi, Gregory F Payne
Oxidative stress is implicated in many diseases yet no simple, rapid and robust measurement is available at the point-of-care to assist clinicians in detecting oxidative stress. Here, we report results from a discovery-based research approach in which a redox mediator is used to probe serum samples for chemical information relevant to oxidative stress. Specifically, we use an iridium salt (K2IrCl6) to probe serum for reducing activities that can transfer electrons to iridium and thus generate detectable optical and electrochemical signals...
December 29, 2016: Analytical Chemistry
Michael Woldegebriel, Eduard Derks
In this work, a novel probabilistic untargeted feature detection algorithm for liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) using artificial neural network (ANN) is presented. The feature detection process is approached as a pattern recognition problem, and thus, ANN was utilized as an efficient feature recognition tool. Unlike most existing feature detection algorithms, with this approach, any suspected chromatographic profile (i.e., shape of a peak) can easily be incorporated by training the network, avoiding the need to perform computationally expensive regression methods with specific mathematical models...
December 29, 2016: Analytical Chemistry
Francesca Gabrieli, Francesca Rosi, Alessandra Vichi, Laura Cartechini, Luciano Pensabene Buemi, Sergei G Kazarian, Costanza Miliani
Protrusions, efflorescence, delamination, and opacity decreasing are severe degradation phenomena affecting oil paints with zinc oxide, one of the most common white pigments of the 20th century. Responsible for these dramatic alterations are the Zn carboxylates (also known as Zn soaps) originated by the interaction of the pigment and the fatty acids resulting from the hydrolysis of glycerides in the oil binding medium. Despite their widespread occurrence in paintings and the growing interest of the scientific community, the process of formation and evolution of Zn soaps is not yet fully understood...
December 28, 2016: Analytical Chemistry
Jody C May, Caleb B Morris, John A McLean
No abstract text is available yet for this article.
December 28, 2016: Analytical Chemistry
Hongqiang Qin, Kai Cheng, Jun Zhu, Jiawei Mao, Fangjun Wang, Mingming Dong, Rui Chen, Zhimou Guo, Xinmiao Liang, Mingliang Ye, Hanfa Zou
The diversity of O-linked glycan structures has drawn increasing attentions due to its vital biological roles. However, intact O-glycopeptides with different glycans are typically not well elucidated using the current methods. In this work, an integrated strategy was developed for comprehensive analysis of O-GalNAc glycosylation by combining hydrophilic interaction chromatography (HILIC) tip enrichment, beam-type collision induced decomposition (beam-CID) detection and in silico deglycosylation method for spectra interpretation...
December 28, 2016: Analytical Chemistry
Tianyi Li, Liusheng Fan, Yingfeng Wang, Xuebin Huang, Jianguo Xu, Jinxing Lu, Mei Zhang, Wei Xu
Typically dealing with practical samples with very complex matrices, ambient ionization mass spectrometry suffers from low detection sensitivity. In this study, molecular imprinting technology was explored and integrated with membrane electrospray ionization (MESI) method for direct sample analyses. By enriching targeted analytes on molecularly imprinted membrane (MIM), 10- to 50-fold limit of quantitation improvement could be achieved compared to conventional nano-electrospray ionization method or other ambient ionization method...
December 28, 2016: Analytical Chemistry
Vera Bilan, Mario Leutert, Paolo Nanni, Christian Panse, Michael O Hottiger
Protein ADP-ribosylation is a physiologically and pathologically important post-translational modification. Recent technological advances have improved analysis of this complex modification and have led to the discovery of hundreds of ADP-ribosylated proteins in both cultured cells and mouse tissues. Nevertheless, accurate assignment of the ADP-ribose acceptor site(s) within the modified proteins identified has remained a challenging task. This is mainly due to poor fragmentation of modified peptides. Here, using an Orbitrap Fusion Tribrid mass spectrometer, we present an optimized methodology that not only drastically improves the overall localization scores for the ADP-ribosylation acceptor sites, but also boosts ADP-ribosylated peptide identifications...
December 28, 2016: Analytical Chemistry
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