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Shibdas Banerjee, Elumalai Gnanamani, Xin Yan, Richard N Zare
Recent studies have shown that microdroplet reactions are markedly accelerated compared to the corresponding bulk-phase reactions. This raises the question whether all reactions can be sped up by this means. We present a counter example, and we show that the reaction mechanism in microdroplets can differ sharply from that in bulk, especially because of the distinct microdroplet surface environment. This analysis helps to guide us how to choose and control reactions in microdroplets and provides a possible perspective on utilizing microdroplet chemistry to scale up synthesis...
March 23, 2017: Analyst
Si Wang, Zhiqin Yuan, Lijuan Zhang, Yanjun Lin, Chao Lu
Cataluminescence (CTL) is a specific chemiluminescence (CL) occurring on the surface of solid catalysts during heterogeneous catalytic oxidation reactions, and it is still a young technique compared to conventional CL. In recent years, CTL-based sensors have been widely used in the detection of various analytes. We have witnessed many developments in CTL-based sensing systems for the enhancement of sensitivity or selectivity. This review provides a thorough introduction to the history and development of CTL-based sensing systems...
March 22, 2017: Analyst
D E Korenchan, C Taglang, C von Morze, J E Blecha, J W Gordon, R Sriram, P E Z Larson, D B Vigneron, H F VanBrocklin, J Kurhanewicz, D M Wilson, R R Flavell
Imaging tumoral pH may help to characterize aggressiveness, metastasis, and therapeutic response. We report the development of hyperpolarized [2-(13)C,D10]diethylmalonic acid, which exhibits a large pH-dependent (13)C chemical shift over the physiological range. We demonstrate that co-polarization with [1-(13)C,D9]tert-butanol accurately measures pH via(13)C NMR and magnetic resonance spectroscopic imaging in phantoms.
March 21, 2017: Analyst
Yang Liu, Yanan Liu, Jinpyo Lee, Joong Hee Lee, Mira Park, Hak Yong Kim
As one of the most promising fluorometric nanosensors for metal ion sensing, carbon nanodots (C-dots) have developed rapidly in recent years. However, it is still a thorny problem to shield the mutual interference of two metal ions towards C-dots, e.g., Hg(2+) and Fe(3+) ions. In the present work, we propose rational routes for the unique interaction between C-dots and Hg(2+) or Fe(3+). The selectivity of the as-obtained label-free C-dots can be effectively switched by P3O10(5-) and SCN(-). The resultant C-dots possess superior photoluminescence intensity stability in a wide pH range or in certain redox circumstances, which are highly preferred in terms of practical metal-ion detection...
March 20, 2017: Analyst
Seiichi Sakamoto, Gorawit Yusakul, Yumi Tsuneura, Waraporn Putalun, Kazuteru Usui, Tomofumi Miyamoto, Hiroyuki Tanaka, Satoshi Morimoto
Harringtonine (HT) is a promising natural product that is mainly isolated from plants of the genus Cephalotaxus. Due to its remarkable antileukemic activities, HT has been utilized clinically in China for the treatment of acute promyelocytic leukemia (APL). No antibody that recognizes free HT has been reported to date due to the difficulty of preparing antigen conjugates in which haptens bind to a carrier protein. To overcome this difficulty, we focused on sodium periodate (NaIO4), which catalyzes unique oxidative reactions; the resulting conjugates enabled the production of a highly specific monoclonal antibody (MAb) against HT (MAb 1D2) and the establishment of an indirect competitive enzyme-linked immunosorbent assay (icELISA) for the determination of HT...
March 17, 2017: Analyst
C M Daikuzono, C Delaney, H Tesfay, L Florea, O N Oliveira, A Morrin, D Diamond
Herein we present a novel sensor for the detection of monosaccharides (e.g. glucose, fructose) in solution, using electrical impedance spectroscopy. The sensor is based on carbon interdigitated electrodes, printed on paper using screen printing. The surface of the electrodes was modified with a thin layer of hydrogel containing acrylamide copolymerised with 20 mol% 3-(Acrylamido)phenylboronic acid (PBA). It was observed that the hydrogel layers containing 20 mol% PBA swell considerably in the presence of glucose and fructose...
March 16, 2017: Analyst
Juan Bian, Susan V Olesik
Polyacrylonitrile/Nafion®/carbon nanotube (PAN/Nafion®/CNT) composite nanofibers were prepared using electrospinning. These electrospun nanofibers were studied as possible substrates for surface-assisted laser desorption/ionization (SALDI) and matrix-enhanced surface-assisted laser desorption/ionization time-of-flight mass spectrometry (ME-SALDI/TOF-MS) for the first time in this paper. Electrospinning provides this novel substrate with a uniform morphology and a narrow size distribution, where CNTs were evenly and firmly immobilized on polymeric nanofibers...
March 15, 2017: Analyst
Jiaxin Chen, Yongjun Hu, Qiao Lu, Pengchao Wang, Huaqi Zhan
Localization and quantification of the target drug in tissues is a key indicator of efficacy in drug discovery. In contrast to established methods that require matrices and complex sample pretreatment steps, matrix-free and low cost in situ analysis of small molecule drugs by mass spectrometry (MS) remains challenging. Here, we present a novel approach, laser desorption postionization (LDPI), which is coupled to a linear time-of-flight (TOF) MS and used to image the distribution of acriflavine (ACF) directly from a histological section of mouse kidney without any matrix or sample pretreatment...
March 15, 2017: Analyst
Hyun Soo Kim, Sergio C Waqued, Dawson T Nodurft, Timothy P Devarenne, Vladislav V Yakovlev, Arum Han
Lipids produced by microalgae are viewed as a potential renewable alternative to fossil fuels, however, significant improvements in productivity are required for microalgal biofuels to become economically feasible. Here we present a method that allows for the use of Raman spectroscopy with poly(dimethylsiloxane) (PDMS) droplet microfluidic devices, which not only overcomes the high Raman background of PDMS, but also achieves pairing of the high-throughput single-cell resolution advantages of droplet microfluidics with the direct, chemically specific, label-free, and non-destructive nature of Raman spectroscopy...
March 15, 2017: Analyst
Flávia de Souza Lins Borba, Tariq Jawhari, Ricardo Saldanha Honorato, Anna de Juan
This article describes a non-destructive analytical method developed to solve forensic document examination problems involving crossed lines and obliteration. Different strategies combining confocal Raman imaging and multivariate curve resolution-alternating least squares (MCR-ALS) are presented. Multilayer images were acquired at subsequent depth layers into the samples. It is the first time that MCR-ALS is applied to multilayer images for forensic purposes. In this context, this method provides a single set of pure spectral ink signatures and related distribution maps for all layers examined from the sole information in the raw measurement...
March 13, 2017: Analyst
Yanli Guo, Aihua Niu, Feifei Jian, Ying Wang, Fujun Yao, Yongfeng Wei, Lei Tian, Xiaofeng Kang
Chiral recognition at single-molecule level for small active molecules is important, as exhibited by many nanostructures and molecular assemblies in biological systems, but it presents a significant challenge. We report a simple and rapid sensing strategy to discriminate all enantiomers of natural aromatic amino acids (AAA) using a metal-organic complex-functionalized protein nanopore, in which a chiral recognition element and a chiral recognition valve were equipped. A trifunctional molecule, heptakis-(6-deoxy-6-amino)-β-cyclodextrin (am7βCD), was non-covalently lodged within the nanopore of an α-hemolysin (αHL) mutant, (M113R)7-αHL...
March 10, 2017: Analyst
Huihun Jung, Chester J Szwejkowski, Abdon Pena-Francesch, John A Tomko, Benjamin Allen, Şahin Kaya Özdemir, Patrick Hopkins, Melik C Demirel
We report the development of a new technique to screen protein aggregation based on laser-probing spectroscopy with sub-picosecond resolution. Protein aggregation is an important topic for materials science, fundamental biology as well as clinical studies in neurodegenerative diseases and translation studies in biomaterials engineering. However, techniques to study protein aggregation and assembly are limited to infrared spectroscopy, fluorescent assays, immunostaining, or functional assays among others. Here, we report a new technique to characterize protein structure-property relationship based on ultrafast laser-probing spectroscopy...
March 9, 2017: Analyst
I J Jahn, O Žukovskaja, X-S Zheng, K Weber, T W Bocklitz, D Cialla-May, J Popp
The exhaustive body of literature published in the last four years on the development and application of systems based on surface-enhanced Raman spectroscopy (SERS) combined with microfluidic devices demonstrates that this research field is a current hot topic. This synergy, also referred to as lab-on-a-chip SERS (LoC-SERS) or nano/micro-optofluidics SERS, has opened the door for new opportunities where both techniques can profit. On the one hand, SERS measurements are considerably improved because the processes previously performed on a large scale in the laboratory and prone to human error can now be carried out in nanoliter volumes in an automatic and reproducible manner; on the other hand, microfluidic platforms need detection methods able to sense in small volumes and therefore, SERS is ideal for this task...
March 9, 2017: Analyst
Atcha Totachawattana, Mi K Hong, Shyamsunder Erramilli, Michelle Y Sander
We report a novel nonlinear mid-infrared vibrational spectroscopy regime where multiple bifurcations and signal enhancement are observed in the photothermal spectrum of a 6 μm-thick layer of 4-octyl-4'-cyanobiphenyl (8CB) liquid crystal. For increasing pump power values, the nonlinear evolution of the photothermal spectrum is studied in 8CB samples initially in the crystalline and smectic-A phase and their non-equilibrium transitions are characterized with pump-probe thermal lens spectroscopy. The nonlinear photothermal phenomena can be explained by the nucleation of localized non-equilibrium transitions that leads to the formation of bubbles, which modify the thermal lensing behavior...
March 9, 2017: Analyst
Yuan Liu, Lu Zhang, Na Zhao, Yajie Han, Feilang Zhao, Zhengchun Peng, Yingchun Li
A highly sensitive electrochemical sensor based on a carbon paste electrode (CPE) modified with molecularly imprinted polymeric microspheres (MIPMSs) was developed for the determination of bisphenol A (BPA). For the first time BPA-imprinted MIPMSs were prepared via distillation precipitation polymerization, and then the polymeric microspheres were involved in producing the MIPMS-modified CPE (MIPMS/CPE). The polymers obtained were observed via a scanning electron microscope and its dynamic and static adsorption performances were investigated...
March 8, 2017: Analyst
Abdu Subaihi, Howbeer Muhamadali, Shaun T Mutter, Ewan Blanch, David I Ellis, Royston Goodacre
In this study surface enhanced Raman scattering (SERS) combined with the isotopic labelling (IL) principle has been used for the quantification of codeine spiked into both water and human plasma. Multivariate statistical approaches were employed for the analysis of these SERS spectral data, particularly partial least squares regression (PLSR) which was used to generate models using the full SERS spectral data for quantification of codeine with, and without, an internal isotopic labelled standard. The PLSR models provided accurate codeine quantification in water and human plasma with high prediction accuracy (Q(2))...
March 8, 2017: Analyst
Jinhong Gao, Zhuoru Li, Ouyang Zhang, Chuanliu Wu, Yibing Zhao
Inspired by the primitive role of lipopolysaccharide (LPS) and taking advantage of the membrane-philic properties of amphiphilic gold nanoparticles (AuNPs), we established a facile and efficient fluorescence turn-on detection strategy for LPS. Upon binding onto the surface of liposomes, LPS can tailor the accessibility of liposomes towards AuNPs, reminiscent of its primitive function on the surface of bacteria. Thus, while the fluorescence of the dyes labeled on liposomes can be markedly quenched by the membrane-philic AuNPs, the quenching effect can be efficiently prevented by the surface-bound LPS...
March 7, 2017: Analyst
Yehia M Ibrahim, Ahmed M Hamid, Liulin Deng, Sandilya V B Garimella, Ian K Webb, Erin S Baker, Richard D Smith
Structures for lossless ion manipulations (SLIM) provide a new paradigm for efficient, complex and extended gas phase ion manipulations. SLIM are created from electric fields generated by the application of DC and RF potentials to arrays of electrodes patterned on two parallel surfaces. The electric fields provide lossless ion manipulations, including effective ion transport and storage. SLIM modules have been developed using both constant and oscillatory electric fields (e.g. traveling waves) to affect the ion motion...
March 6, 2017: Analyst
Zuriñe Abrego, Nora Unceta, Alicia Sánchez, Alberto Gómez-Caballero, Luis Maria Berrio-Ochoa, M Aranzazu Goicolea, Ramón J Barrio
Environmental pollution by mercury in ambient water samples is a recognized problem worldwide. Sample preservation and transport to the laboratory lead to uncertain analytical results. This study outlines the development of a procedure for on-site electrodeposition of mercury from water samples on a screen-printed gold electrode (SPGE) using portable voltammetric techniques. Once in the laboratory, Hg is analyzed by laser ablation inductively coupled plasma-mass spectrometry (LA-ICPMS) in order to ensure that the required sensitivity and precision levels for environmental sample analysis are reached...
March 6, 2017: Analyst
Gregory T Roman, James P Murphy
We demonstrate an integrated microfluidic LC device coupled to a QTOF capable of improving sensitivity and linearity for intact protein analysis while also tuning the charge state distributions (CSD) of whole antibodies. The mechanism for sensitivity improvement using microflow ESI is demonstrated by shifting of the CSD to higher charge state, and narrowing of the overall CSD. Both of these aspects serve to improve ion current of the most abundant charge state of antibodies and lead to improvement in sensitivity over high flow ESI by a factor of 15×...
March 2, 2017: Analyst
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