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Analytical Methods: Advancing Methods and Applications

Qun Cao, Pumidech Puthongkham, B Jill Venton
The carbon-fiber microelectrode has been used for decades as a neurotransmitter sensor. Recently, new strategies have been developed for making carbon electrodes, including using carbon nanomaterials or pyrolyzing photoresist etched by nanolithography or 3D printing. This review summarizes how chemical and 3D surface structures of new carbon electrodes are optimized for neurotransmitter detection. There are effects of the chemical structure that are advantageous and nanomaterials are used ranging from carbon nanotube (CNT) to graphene to nanodiamond...
January 21, 2019: Analytical Methods: Advancing Methods and Applications
Emily Parry, Stuart A Willison
Sodium fluoroacetate or Compound 1080 is a rodenticide registered in the United States for use in livestock protection collars. The collars are employed to control predation on herd animals (i.e., killing of cattle by wolves or coyotes). Sodium fluoroacetate is acutely toxic to humans and has potential to cause mass casualties if used to intentionally contaminate water systems. The U.S. Environmental Protection Agency (EPA) is responsible for characterization and remediation if such an incident occurs in the civilian sector...
December 14, 2018: Analytical Methods: Advancing Methods and Applications
Jean T Negou, Juan Hu, Xiangpeng Li, Christopher J Easley
In this work, we expand upon our recently developed droplet-based sample chopping concepts by introducing a multiplexed fluidic micro-chopper device (╬╝Chopper). Six aqueous input channels were integrated with a single oil input, and each of these seven channels was controlled by a pneumatic valve for automated sampling through software control. This improved design, while maintaining high precision in valve-based droplet generation at bandwidths of 0.03 to 0.05 Hz, enabled a variety of analytical modes to be employed on-chip compared to previous devices limited to sample/reference alternations...
July 28, 2018: Analytical Methods: Advancing Methods and Applications
Levan Lomidze, Tyler H Williford, Karin Musier-Forsyth, Besik Kankia
Amplification of long DNA segments with the highest possible specificity and lowest bias is one of the main goals of modern genomics. Quadruplex priming amplification (QPA) is a single-primer isothermal method, which employs the free energy of quadruplex structures as the driving force for DNA amplification without any extra reaction components. As a result, QPA represents one of the simplest isothermal assays and was previously shown to be suitable for amplification of relatively short DNA sequences. The current study reveals that single-primer QPA can be used for both exponential and linear amplification of relatively long DNA segments (>100 nt), and switching between these modes can be accomplished by simple re-design of the primer used...
July 7, 2018: Analytical Methods: Advancing Methods and Applications
Richard M Graybill, Maria C Cardenosa-Rubio, Hongwei Yang, Mark D Johnson, Ryan C Bailey
Analysis methods based upon the quantitative, real-time polymerase chain reaction are extremely powerful; however, they face intrinsic limitations in terms of target multiplexing. In contrast, silicon photonic microring resonators represent a modularly multiplexable sensor array technology that is well-suited to the analysis of targeted biomarker panels. In this manuscript we employ an asymmetric polymerase chain reaction approach to selectively amplify copies of cDNAs generated from targeted miRNAs before multiplexed, label-free quantitation through hybridization to microring resonator arrays pre-functionalized with capture sequences...
April 14, 2018: Analytical Methods: Advancing Methods and Applications
Elizabeth L Robinson, Edward Sisco, Matthew E Staymates, Jeffrey A Lawrence
Trace explosives detection, a crucial component of many security screening environments, commonly employs wipe-sampling. Since collection of an explosive residue is necessary for detection, it is important to have a thorough understanding of the parameters that affect the efficiency of collection. Current wipe-sampling evaluation techniques for explosive particles have their limits: manual sampling (with fingers or a wand) is limited in its ability to isolate a single parameter and the TL-slip/peel tester is limited to a linear sample path...
January 14, 2018: Analytical Methods: Advancing Methods and Applications
Benjamin T Mehl, R Scott Martin
The ability to use microchip-based electrophoresis for fast, high-throughput separations provides researchers with a tool for close-to real time analysis of biological systems. While PDMS-based electrophoresis devices are popular, the separation efficiency is often an issue due to the hydrophobic nature of PDMS. In this study, a hybrid microfluidic capillary device was fabricated to utilize the positive features of PDMS along with the electrophoretic performance of fused silica. A capillary loop was embedded in a polystyrene base that can be coupled with PDMS microchannels at minimal dead volume interconnects...
January 7, 2018: Analytical Methods: Advancing Methods and Applications
Jinlan Dong, Wenjing Ning, Daniel J Mans, Jamie D Mans
A mixture of ╬▒-cyano-4-hydroxycinnamic acid and 1,5-diaminonaphthalene was discovered as a novel binary matrix for the qualitative analysis of 14 small-molecule (~250-550 Da) cardiovascular drugs by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and MS/MS in either positive or negative ion mode.
2018: Analytical Methods: Advancing Methods and Applications
Jude C Lakbub, Xiaomeng Su, David Hua, Eden P Go, Heather Desaire
The need to investigate the fragmentation of fucosylated glycopeptides is driven by recent work showing that at least one, and perhaps many, glycopeptide analysis scoring algorithms are less effective at identifying fucosylated glycopeptides than non-fucosylated glycopeptides. Herein, we study the CID fragmentation characteristics of fucosylated glycopeptides and the scoring rules of the glycopeptide analysis software, GlycoPep Grader, in an effort to improve automated assignments of these important glycopeptides...
2018: Analytical Methods: Advancing Methods and Applications
James E Keating, John T Minges, Scott H Randell, Gary L Glish
The rapid release of new tobacco products requires high-throughput quantitative methods to support tobacco research. Sample preparation for LC-MS and GC-MS is time consuming and limits throughput. Paper spray tandem mass spectrometry (PS-MS/MS) is proposed and validated as a simple and rapid method for quantification of nicotine and cotinine in complex matrices to support tobacco-related research. Air liquid interface (ALI) human tracheobronchial epithelial cell (HTBEC) cultures were exposed to tobacco smoke using a Vitrocell VC-10 smoking machine...
2018: Analytical Methods: Advancing Methods and Applications
Lifu Xiao, Abdul K Parchur, Timothy A Gilbertson, Anhong Zhou
G-protein-coupled receptor 120 (GPR120), as a member of the rhodopsin family of G-protein-coupled receptors, has been shown to function as a sensor for dietary fat in the gustatory and digestive systems. Its specific role in the chemoreception of fatty acids, which is thought to be crucial in understanding the mechanism surrounding the control of fat intake and, accordingly, in the treatment of obesity, remains unclear. Here we report a novel surface-enhanced Raman spectroscopy (SERS)-fluorescence bimodal microscopic technique for detection and imaging of GPR120 in single living cells...
2018: Analytical Methods: Advancing Methods and Applications
Rosemary M Onjiko, David O Plotnick, Sally A Moody, Peter Nemes
Single-cell mass spectrometry (MS) empowers the characterization of metabolomic changes as cells differentiate to different tissues during early embryogenesis. Using whole-cell dissection and capillary electrophoresis electrospray ionization (CE-ESI) MS, we recently uncovered metabolic cell-to-cell differences in the 8- and 16-cell embryo of the South African clawed frog ( Xenopus laevis ), raising the question whether metabolic cell heterogeneity is also detectable across the dorsal-ventral axis of the 8-cell embryo...
September 14, 2017: Analytical Methods: Advancing Methods and Applications
Mumiye A Ogunwale, Yizheng Chen, Whitney S Theis, Michael H Nantz, Daniel J Conklin, Xiao-An Fu
The electronic cigarette (e-cigarette) has emerged as popular electronic nicotine delivery devices (ENDs). However, the general safety and validity of e-cigarettes for nicotine delivery efficacy are still not well understood. This study developed a new method for efficient measurement of nicotine levels in both the liquids (e-liquids) used in e-cigarettes and the aerosols generated from the e-cigarettes. Protonation of the pyrrolidine nitrogen of nicotine molecules by addition of excess hydrochloric acid affords an aminium salt that is readily quantified by Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS)...
August 7, 2017: Analytical Methods: Advancing Methods and Applications
Lee L Yu, Rachel C Stanoyevitch, Rolf Zeisler
A dietary supplement, kelp contains a significant amount of arsenic that is mostly arsenosugars. The determination of arsenosugars is difficult due to a lack of arsenosugar calibration standard, because arsenosugar compounds are not commercially available. This work reports the determination of arsenicals in a kelp extract with traceability to the International System of Units (SI). The hydrophilic fraction of arsenicals was reproducibly extracted from a candidate Standard Reference Material (SRM) 3232 Kelp Powder ( Thallus Laminariae ) in development at the National Institute of Standards and Technology (NIST)...
August 2017: Analytical Methods: Advancing Methods and Applications
Gabe Nagy, Tianyuan Peng, Nicola L B Pohl
Carbohydate purification remains a bottleneck in securing analytical standards from natural sources or by chemical or enzymatic synthesis. This review highlights the scope and remaining limitations of recent approaches and methods development in liquid chromatography for robust and higher-throughput carbohydrate separation and isolation.
June 28, 2017: Analytical Methods: Advancing Methods and Applications
Chengpeng Chen, Alexandra D Townsend, Scott A Sell, R Scott Martin
Polymer nano/micro fibers have found many applications including 3D cell culture and the creation of wound dressings. The fibers can be produced by a variety of techniques that include electrospinning, the primary disadvantage of which include the requirement for a high voltage supply (which may cause issues such as polymer denaturation) and lack of portability. More recently, solution blow spinning, where a high velocity sheath gas is used instead of high voltage, has been used to generate polymer fibers. In this work, we used blow spinning to create nano/microfibers for microchip-based 3D cell culture...
June 14, 2017: Analytical Methods: Advancing Methods and Applications
X Wei, P K Lorkiewicz, B Shi, J K Salabei, B G Hill, S Kim, C J McClain, X Zhang
Stable isotope assisted metabolomics (SIAM) uses stable isotope tracers to support studies of biochemical mechanisms. We report a suite of data analysis algorithms for automatic analysis of SIAM data acquired on a high resolution mass spectrometer. To increase the accuracy of isotopologue assignment, metabolites detected in the unlabeled samples were used as reference metabolites to generate possible isotopologue candidates for analysis of peaks detected in the labeled samples. An iterative linear regression model was developed to deconvolute the overlapping isotopic peaks of isotopologues present in a full MS spectrum, where the threshold for the weight factor was determined by a simulation study assuming different levels of Gaussian white noise contamination...
April 21, 2017: Analytical Methods: Advancing Methods and Applications
M R Williams, R D Stedtfeld, H Waseem, T Stedtfeld, B Upham, W Khalife, B Etchebarne, M Hughes, J M Tiedje, S A Hashsham
Antimicrobial resistance (AMR) is recognized as a global threat to human health. Rapid detection and characterization of AMR is a critical component of most antibiotic stewardship programs. Methods based on amplification of nucleic acids for detection of AMR are generally faster than culture-based approaches but they still require several hours to more than a day due to the need for transporting the sample to a centralized laboratory, processing of sample, and sometimes DNA purification and concentration. Nucleic acids-based point-of-care (POC) devices are capable of rapidly diagnosing antibiotic-resistant infections which may help in making timely and correct treatment decisions...
February 28, 2017: Analytical Methods: Advancing Methods and Applications
Hesam Babahosseini, Jeannine S Strobl, Masoud Agah
This study describes the development of a microfluidic biosensor called the iterative mechanical characteristics (iMECH) analyzer which enables label-free biomechanical profiling of individual cells for distinction between metastatic and non-metastatic human mammary cell lines. Previous results have demonstrated that pulsed mechanical nanoindentation can modulate the biomechanics of cells resulting in distinctly different biomechanical responses in metastatic and non-metastatic cell lines. The iMECH analyzer aims to move this concept into a microfluidic, clinically more relevant platform...
February 7, 2017: Analytical Methods: Advancing Methods and Applications
Michael D Hambuchen, Howard P Hendrickson, S Michael Owens
The emerging stimulant drug of abuse (3,4)-methylenedioxypyrovalerone [( R,S )-MDPV] is self-administered as a racemic mixture by intranasal, iv, oral, and smoking routes. The individual enantiomers are known to have widely different pharmacological effects, with ( S )-MDPV showing much greater potency than ( R )-MDPV in pharmacological testing. The goal of these studies was to develop and validate an analytical method for quantitation of ( R )-MDPV, ( S )-MDPV and ( R,S )-MDPV in small volumes of rat serum using a chiral separation column and liquid chromatography-mass spectrometry...
January 28, 2017: Analytical Methods: Advancing Methods and Applications
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