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Analytical chemistry

Huifeng Yu, Yanming An, Marcos Daniel Battistel, John F Cipollo, Darón I Freedberg
Conjugate vaccines are highly heterogeneous in terms of glycosylation sites and linked oligosaccharide length. Therefore, the characterization of conjugate vaccines' glycosylation state is challenging. However, improved product characterization can lead to enhancements in product control and product quality. Here, we present a synergistic combination of high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy for the analysis of glycoconjugates. We use the power of this strategy to characterize model polysaccharide conjugates to demonstrate a detailed level of glycoproteomic analysis...
March 21, 2018: Analytical Chemistry
Cezar A Bizzi, Sandra M Cruz, Lucas Schmidt, Robert A Burrow, Juliano S Barin, Jose N G Paniz, Erico M M Flores
A new method for analytical applications based on the Maxwell-Wagner effect is proposed. Considering the interaction of carbonaceous materials with an electromagnetic field in the microwave frequency range, a very fast heating is observed due to interfacial polarization that results in localized microplasma formation. Such effect was evaluated in this work using a monomode microwave system, and temperature was recorded using an infrared camera. For analytical applications, a closed reactor under oxygen pressure was evaluated...
March 21, 2018: Analytical Chemistry
Yunfang Jia, Fang Li
Functional nucleic acids (FNAs) are promising sensing elements, extensive interests are excited to integrate FNAs with transducers for biochemical assays. However, efforts for FNAs modified light-addressable-potentiometric-sensor (FNA-LAPS) are rarely reported. LAPS is a versatile transducer with electrolyte-insulator-semiconductor (EIS) structure, can respond almost any surface electronic deviations. Herein, organized studies for FNA-LAPS including experiments, theoretical derivations and MEDICI (Synopsys®) simulations, are presented using Pb2+ -DNAzyme GR-5 and Ag+ -aptamer as proof-of-concepts, which are typical FNAs with distinctive sensing strategies...
March 21, 2018: Analytical Chemistry
Ben Buse, Stuart Kearns
Automated phase maps are an important tool for characterizing samples but the data quality must be evaluated. Common options include the overlay of phases on backscattered electron (BSE) images and phase composition averages and standard deviations. Both these methods have major limitations. We propose two methods of evaluation involving principal component analysis. First, a red-green-blue composite image of the first three principal components, which comprise the majority of the chemical variation, which provides a good reference against which phase maps can be compared...
March 21, 2018: Microscopy and Microanalysis
Shilpa N Raja, Xingchen Ye, Matthew R Jones, Liwei Lin, Sanjay Govindjee, Robert O Ritchie
Nanoscale stress sensing is of crucial importance to biomechanics and other fields. An ideal stress sensor would have a large dynamic range to function in a variety of materials spanning orders of magnitude of local stresses. Here we show that tetrapod quantum dots (tQDs) exhibit excellent sensing versatility with stress-correlated signatures in a multitude of polymers. We further show that tQDs exhibit pressure coefficients, which increase with decreasing polymer stiffness, and vary >3 orders of magnitude...
March 20, 2018: Nature Communications
Żaneta Bargańska, Dimitra Lambropoulou, Jacek Namieśnik
Bumblebees play an important role in the pollination process of many crops and flowers. Therefore, taking action to protect and assess the impact of pesticides on these insects is fully justified. Pesticides may cause mortality and also sub-lethal effects that are not always directly visible. Bumblebees, like honeybees, can be used as indicators for environmental monitoring contamination. Two approaches are mainly used for the determination of pesticide residues in pollinating insects: a toxicological test (to know effects) and multi-stage analytical methodologies (to know exposure)...
March 20, 2018: Critical Reviews in Analytical Chemistry
Melissa M Galey, Laura M Sanchez
Microbial communities contribute to a wide variety of biological functions in hosts and have the ability to specifically influence the health of those organisms through production of specialized metabolites. However, the structures or molecular mechanisms related to health or disease in host-microbe interactions represent a knowledge gap. In order to close this gap, we propose that a combinatory approach, pulling from microbiology and analytical chemistry, be considered to investigate these interactions so as to gain a better understanding of the chemistry being produced...
March 2018: MSystems
Cameron L Bentley, Alan M Bond, Jie Zhang
Nonhaloaluminate ionic liquids (ILs) have received considerable attention as alternatives to molecular solvents in diverse applications spanning the fields of physical, chemical, and biological science. One important and often overlooked aspect of the implementation of these designer solvents is how the properties of the IL formulation affect (electro)chemical reactivity. This aspect is emphasized herein, where recent (voltammetric) studies on the energetics of proton (H+ ) transfer and electrode reaction mechanisms of the H+ H2 process in IL media are highlighted and discussed...
March 19, 2018: Annual Review of Analytical Chemistry
Ahmed Ma'mun, Mohamed K Abd El-Rahman, Mohamed Abd El-Kawy
In recent years, the whole field of ion-selective electrodes(ISEs) in pharmaceutical sciences has expanded far beyond its original roots. The diverse range of opportunities offered by ISEs was broadly used in a number of pharmaceutical applications, with topics presented ranging from bioanalysis of drugs and metabolites, to protein binding studies, green analytical chemistry, impurity profiling, and drug dissolution in biorelevant media. Inspired from these advances and with the aim of extending the functional capabilities of ISEs, the primary focus of the present paper is the utilization of ISE as a tool in personalized medicine...
February 7, 2018: Journal of Pharmaceutical and Biomedical Analysis
Stéphane Faucher, Philippe Le Coustumer, Gaëtane Lespes
This article deals with analytical chemistry devoted to nano-objects. A short review presents nano-objects, their singularity in relation to their dimensions, genesis, and possible transformations. The term nano-object is then explained. Nano-object characterization activities are considered and a definition of nanoanalytics is proposed. Parameters and properties for describing nano-objects on an individual scale and on the scale of a population are also presented. They enable the specificities of analytical activities to be highlighted in terms of multi-criteria description strategies and observation scale...
March 16, 2018: Environmental Science and Pollution Research International
A Sozza, F Piazza, M Cencini, F De Lillo, G Boffetta
We present an efficient point-particle approach to simulate reaction-diffusion processes of spherical absorbing particles in the diffusion-limited regime, as simple models of cellular uptake. The exact solution for a single absorber is used to calibrate the method, linking the numerical parameters to the physical particle radius and uptake rate. We study the configurations of multiple absorbers of increasing complexity to examine the performance of the method by comparing our simulations with available exact analytical or numerical results...
February 2018: Physical Review. E
Xin Gu, Michael J Trujillo, Jacob E Olson, Jon P Camden
Owing to its extreme sensitivity and easy execution, surface-enhanced Raman spectroscopy (SERS) now finds application for a wide variety of problems requiring sensitive and targeted analyte detection. This widespread application has prompted a proliferation of different SERS-based sensors, suggesting the need for a framework to classify existing methods and guide the development of new techniques. After a brief discussion of the general SERS modalities, we classify SERS-based sensors according the origin of the signal...
March 16, 2018: Annual Review of Analytical Chemistry
Wesley D Allen
The overarching analytic integrated rate equation for the chemical kinetics of any reversible or irreversible reaction involving an arbitrary number of species and any integral orders is shown to be [EQN1], where ξ(t) is the extent of reaction variable, the fi are roots of a polynomial of order r, the exponents are determined by [EQN2] , and F0 is a factor involving the stoichiometric coefficients and rate constants (k± ). All integrated rate equations of elementary reactions appearing in chemical kinetics are special cases of this universal solution...
March 16, 2018: Journal of Physical Chemistry. A
Leontine Mulder, Renate van der Molen, Carin Koelman, Ester van Leeuwen, Anja Roos, Jan Damoiseaux
ISO 15189:2012 requires validation of methods used in the medical laboratory, and lists a series of performance parameters for consideration to include. Although these performance parameters are feasible for clinical chemistry analytes, application in the validation of autoimmunity tests is a challenge. Lack of gold standards or reference methods in combination with the scarcity of well-defined diagnostic samples of patients with rare diseases make validation of new assays difficult. The present manuscript describes the initiative of Dutch medical immunology laboratory specialists to combine efforts and perform multi-center validation studies of new assays in the field of autoimmunity...
March 12, 2018: Autoimmunity Reviews
David R Glenn, Dominik B Bucher, Junghyun Lee, Mikhail D Lukin, Hongkun Park, Ronald L Walsworth
Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen-vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples, with sensitivity sufficient to detect the magnetic field produced by a single protein. However, the best reported spectral resolution for NMR of molecules using nitrogen-vacancy centres is about 100 hertz. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency)...
March 14, 2018: Nature
Francesca Nunzi, Diego Cesario, Fernando Pirani, Leonardo Belpassi, Francesco Tarantelli
We studied the nature of the interaction of the weakly bound Be-He adduct, by means of an integrated theoretical approach, based on high-level quantum chemical calculations for the characterization of the potential energy surfaces and charge displaced upon adduct formation, together with the development of a semi-empirical analytical formulation of the interaction potential. Our results show that Be is able to form stable adduct with He when the Be(1D) (1s2 2s2  1s2 2s0 2p2) excited state is involved, with a binding energy of as much as 10...
March 14, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Ana B Silva, Ana S Bastos, Celine I L Justino, João P da Costa, Armando C Duarte, Teresa A P Rocha-Santos
Microplastics can be present in the environment as manufactured microplastics (known as primary microplastics) or resulting from the continuous weathering of plastic litter, which yields progressively smaller plastic fragments (known as secondary microplastics). Herein, we discuss the numerous issues associated with the analysis of microplastics, and to a less extent of nanoplastics, in environmental samples (water, sediments, and biological tissues), from their sampling and sample handling to their identification and quantification...
August 9, 2018: Analytica Chimica Acta
Detlef Ulrich, Steffen Kecke, Klaus Olbricht
The strawberry, with its unique aroma, is one of the most popular fruits worldwide. The demand for specific knowledge of metabolism in strawberries is increasing. This knowledge is applicable for genetic studies, plant breeding, resistance research, nutritional science, and the processing industry. The molecular basis of strawberry aroma has been studied for more than 80 years. Thus far, hundreds of volatile organic compounds (VOC) have been identified. The qualitative composition of the strawberry volatilome remains controversial though considerable progress has been made during the past several decades...
March 13, 2018: Journal of Agricultural and Food Chemistry
Pramod Singh Negi, Jitendra Singh, Geeta Joshi Nee Pant, Msm Rawat
Nitrogen containing five membered heterocyclics play vital role in pharmaceuticals as well as medicinal chemistry. Pyrazolines play a significant role among other heterocycles because of their therapeutic and pharmacological properties. 2-Pyrazolines displayed a wide variety of biological activities such as anticancer, antiepileptic, anti-aids, antimalarial, insecticidal and antitubercular etc. and they are used as pesticides, herbicides, fungicides and also used in agrochemical research and analytical chemistry...
March 13, 2018: Anti-cancer Agents in Medicinal Chemistry
Liora Werber, Yitzhak Mastai
One of the most powerful techniques that are currently available to measure thermodynamic parameters such as enthalpy (ΔH), Gibbs free energy (ΔG), entropy changes (ΔS), and binding affinity in chemical reactions is isothermal titration calorimetry (ITC). Recent advances in instrumentation have facilitated the development of ITC as a very essential analytical tool in biology and chemistry. In this article, we will focus on a review of the literature on the application of ITC for the study of chiral systems and chiral interactions...
March 12, 2018: Chirality
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