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L Tamina Hagemann, Mitchell M McCartney, Alexander G Fung, Daniel J Peirano, Cristina E Davis, Boris Mizaikoff
Designing mobile devices for the analysis of complex sample mixtures containing a variety of analytes at different concentrations across a large dynamic range remains a challenging task in many analytical scenarios. To meet this challenge, a compact hybrid analytical platform has been developed combining Fourier transform infrared spectroscopy based on substrate-integrated hollow waveguides (iHWG-FTIR) with gas chromatography coupled differential mobility spectrometry (GC-DMS). Due to the complementarity of these techniques regarding analyte type and concentration, their combination provides a promising tool for the detection of complex samples containing a broad range of molecules at different concentrations...
September 20, 2018: Analyst
Anthony Dicken, Daniel Spence, Keith Rogers, Danae Prokopiou, Paul Evans
To retrieve crystallographic information from extended sample volumes requires a high-energy probe. The use of X-rays to combine imaging with materials characterisation is well-established. However, if fundamental crystallographic parameters are required, then the collection and analysis of X-rays diffracted by the inspected samples are prerequisites. We present a new X-ray diffraction imaging architecture, which in comparison with previous depth-resolving hollow beam techniques requires significantly less X-ray power or alternatively supports significantly increased scanning speeds...
September 19, 2018: Analyst
Qiong Wu, Fengxia Zhang, Huijuan Li, Zhihua Li, Qi Kang, Dazhong Shen
Herein, we report a ratiometric photoelectrochemical (PEC) immunosensor coupled with secondary antibodies-Co3O4 nanoparticle conjugates (Ab2-Co3O4 NPs) for signal amplification. The Ab1-g-C3N4@TiO2 NTs and BSA-g-C3N4@TiO2 NTs act as the sensing and reference photoelectrodes, where Ab1, BSA and TiO2 NTs are the capture antibodies, bovine serum albumin and TiO2 nanotube arrays, respectively. In the presence of target Ag, the sensing PEC photocurrent decreases due to the steric hindrance of Ab1 molecules, which increases the inner resistance of the photoelectrode...
September 19, 2018: Analyst
Pei Wang, Jonas Balko, Rui Lu, Ángela I López-Lorente, Lutz Dürselen, Boris Mizaikoff
Degeneration of human meniscal tissue induces impairment of normal knee functions, and is a highly relevant etiology of knee joint tears and osteoarthritis. Currently, the grading scale of meniscus degeneration is conventionally derived from evaluating meniscal morphology and histological staining. However, mid-infrared attenuated total reflectance (IR-ATR) spectroscopy is a particularly useful technique that may analyze the biomolecular composition at a sample surface, and provide information on the intra- and/or inter-molecular chemical bonds...
September 19, 2018: Analyst
Wenming Wu
The micropump is the most important functional unit of a micro total analysis system (μTAS). An ideal microfluidics system should adopt simple, stable, robust, inexpensive, and integrated on-chip strategies to transport samples for downstream applications, with little or no external energy consumption and limited manual intervention. Nevertheless, it remains a key challenge for traditional micropumps to be directly integrated into self-contained and disposable μTAS for velocity-stable and passive sample transport...
September 19, 2018: Analyst
Karen E Yannell, Christina R Ferreira, Shane E Tichy, R Graham Cooks
Metabolite profiling by mass spectrometry (MS) is an area of interest for disease diagnostics, biomarker discovery, and therapeutic evaluation. A recently developed approach, multiple reaction monitoring (MRM)-profiling, searches for metabolites with precursor (Prec) and neutral loss (NL) scans in a representative sample and creates a list of ion transitions. These are then used in an MRM method for fast screening of individual samples and discrimination between healthy and diseased. A large variety of functional groups are considered and all signals discovered are recorded in the individual samples, making this a largely unsupervised method...
September 18, 2018: Analyst
Ripon Bhattacharjee, Sofia Moriam, Muhammad Umer, Nam-Trung Nguyen, Muhammad J A Shiddiky
DNA methylation is one of the significant epigenetic modifications involved in mammalian development as well as in the initiation and progression of various diseases like cancer. Over the past few decades, an enormous amount of research has been carried out for the quantification of DNA methylation in the mammalian genome. Earlier, most of these methodologies used bisulfite treatment. However, the low conversion, false reading, longer assay time and complex chemical reaction are the common limitations of this method that hinder their application in routine clinical screening...
September 18, 2018: Analyst
Bo Wang, Bonhye Koo, Li-Wen Huang, Harold G Monbouquette
High performance microprobes for combined sensing of glucose and choline were fabricated using microcontact printing (μCP) to transfer choline oxidase (ChOx) and glucose oxidase (GOx) onto targeted sites on microelectrode arrays (MEAs). Most electroenzymatic sensing sites on MEAs for neuroscience applications are created by manual enzyme deposition, which becomes problematic when the array feature size is less than or equal to ∼100 μm. The μCP process used here relies on use of soft lithography to create features on a polydimethylsiloxane (PDMS) microstamp that correspond to the dimensions and array locations of targeted, microscale sites on a MEA...
September 18, 2018: Analyst
Lanfang Zou, Brittany Kassim, Joseph P Smith, James D Ormes, Yong Liu, Qiang Tu, Xiaodong Bu
Laser induced breakdown spectroscopy (LIBS) has emerged as an innovative tool for quantitative and qualitative elemental analysis in pharmaceutical research. Herein, the potential use of LIBS for rapid characterization of tablet coatings is illustrated, including the investigation of coating thickness, coating uniformity and localized coating contamination. The laser shot number required for penetrating the coating correlates well with coating thickness determined from traditional scanning electron microscopy measurements...
September 18, 2018: Analyst
Ya-Fei Tian, Cui-Fang Ning, Fang He, Bin-Cheng Yin, Bang-Ce Ye
Exosomes, as important signal transmitters, play a key role in intercellular communication, especially in cancer metastasis. There is considerable evidence that exosomes can be used as an indicator of cancer. However, convenient and sensitive methods for detecting exosomes are still technically challenging. Here, we present a convenient and highly sensitive surface-enhanced Raman scattering (SERS) based method by combining immunoaffinity, SERS nanoprobes, and portable Raman devices for specific isolation and accurate quantification of exosomes...
September 18, 2018: Analyst
Ruijun Wu, Cong Li, Xiaozhi Sun, Sufang Zhang, Chunsu Liang, Yong Jiang, Xin Hu, Youqi Yan, Xiaomei Ling
In this research a method called immobilized cell capillary electrophoresis (ICCE) was established under approximately physiological conditions for rapid screening of anti-tumor metastasis drugs targeting integrin macrophage antigen-1 (MAC-1). In this method, separation and purification of the target receptors on cell membranes was unnecessary, thus, maintaining their natural conformation and bioactivity. MAC-1-, CD11b-, or CD18-overexpressing HEK293 cells (human embryonic kidney) were cultured and immobilized on the inner wall of capillaries as stationary phase, and their interactions with lactosyl derivative Gu-4 (positive control)/dimethylsulfoxide (DMSO; negative control) were studied using ICCE...
September 18, 2018: Analyst
Haiping Wu, Xiaoyan Zhou, Wei Cheng, Taixian Yuan, Min Zhao, Xiaolei Duan, Shijia Ding
A one-step, rapid fluorescence biosensing method has been developed for ultrasensitive detection of the BCR-ABL1 fusion gene based on a polymerase/nicking endonuclease DNA machine and multiple primer-like rolling circle amplification (RCA). In the strategy, the BCR-ABL1 fusion gene can be specifically identified by using a dual probe to form a three-way junction structure (3-WJ). Then the 3-WJ based DNA machine is driven by polymerase and nicking endonuclease to generate a large number of triggers, initiating a downstream RCA reaction...
September 18, 2018: Analyst
Jose F Rivera, Siddarth V Sridharan, James K Nolan, Stephen A Miloro, Muhammad A Alam, Jenna L Rickus, David B Janes
Extracellular measurement of uptake/release kinetics and associated concentration dependencies provides mechanistic insight into the underlying biochemical processes. Due to the recognized importance of preserving the natural diffusion processes within the local microenvironment, measurement approaches which provide uptake rate and local surface concentration of adherent cells in static media are needed. This paper reports a microelectrode array device and a methodology to measure uptake kinetics as a function of cell surface concentration in adherent 2D cell cultures in static fluids...
September 18, 2018: Analyst
Fay Nicolson, Lauren E Jamieson, Samuel Mabbott, Konstantinos Plakas, Neil C Shand, Michael R Detty, Duncan Graham, Karen Faulds
The ability to probe through barriers and tissue non-invasively is an urgent unmet need in both the security and biomedical imaging fields. Surface enhanced Raman spectroscopy (SERS) has been shown to yield superior enhancement in signal over conventional Raman techniques. Furthermore, by utilising a resonant Raman reporter to produce surface enhanced resonance Raman spectroscopy (SERRS), even greater enhancement in chemical signal can be generated. Here we show the benefit of using red-shifted chalcogenpyrylium based Raman reporters for probing through large thicknesses of plastic and tissue barriers using a conventional Raman instrument...
September 18, 2018: Analyst
Maxim E Darvin, Johannes Schleusener, Franziska Parenz, Olaf Seidel, Christoph Krafft, Jürgen Popp, Jürgen Lademann
Raman measurements applied on freshly tattooed porcine skin ex vivo showed a possibility of obtaining the ink pigment related information in the skin. Based on these results, confocal Raman microscopy was used to identify the tattoo ink pigments of different colors in multicolored tattooed human skin in vivo. The Raman signatures of tattoo ink pigments were unique. Therefore, it could be shown that the applied method is successful for the identification of the tattoo ink pigments in human skin in vivo down to depths of approx...
September 18, 2018: Analyst
Paweł M Nowak, Michał Woźniakiewicz
We demonstrate that microscale thermophoresis can be easily coupled with capillary electrophoresis in an on-line flow system (CE-MST), offering new potential possibilities. It takes advantage of sample separation and miniaturization prior to thermo-optical/MST analysis. No instrument modification is required. The future perspective is discussed.
September 18, 2018: Analyst
Hong-Min Meng, Di Zhao, Na Li, Junbiao Chang
A multifunctional nanosystem, which integrates biosensing, bioimaging, and therapeutic functions into a single nanoprobe, is of great significance for biosensing and biomedicine. Near-infrared (NIR) graphene quantum dots (GQDs) have emerged as an attractive bioimaging and therapy tool for exploring biological events because they can provide deep imaging penetration and low fluorescence background and produce 1O2 for PDT. Here, we reported a GQD-based multifunctional two-photon nanoprobe for intracellular tumor-related glutathione (GSH) detection and enhanced photodynamic therapy by reducing GSH levels in cancer cells...
September 18, 2018: Analyst
Takao Ono, Takanori Ichiki, Hiroyuki Noji
Single-molecule digital enzyme assay using micron-sized droplet array is a promising analysis method to quantify biomolecules at extremely low concentrations. However, multiplex digital enzyme assays are still difficult to access because the best buffer conditions can vary largely among enzymes. In addition, the best conditions for flurogenic compounds to retain high quantum efficiency and to avoid leakage into the oil phase can be also very different. In this study, digital enzyme assay was performed using an array of nanometer-sized droplets of 200 aL volume, termed 'nanocell'...
September 17, 2018: Analyst
S A Currivan, W Q Chen, R Wilson, E Sanz Rodriguez, N Upadhyay, D Connolly, P N Nesterenko, B Paull
In this work we evaluated a novel microreactor prepared using a surface modified, high surface-to-volume ratio multi-lumen fused silica capillary (MLC). The MLC investigated contained 126 parallel channels, each of 4 μm internal diameter. The MLC, along with conventional fused silica capillaries of 25 μm and 50 μm internal diameter, were treated by (3-aminopropyl)triethoxysilane (APTES) and then modified with gold nanoparticles, of ∼20 nm in diameter, to ultimately provide immobilisation sites for the proteolytic enzyme, trypsin...
September 17, 2018: Analyst
Daojin Li, Zijun Bie, Fangfang Wang, Enhui Guo
Riboflavin (vitamin B2), a cis-diol-containing compound, is an essential vitamin for maintaining human health mainly in energy metabolism and is a critical component of enzyme cofactors and flavoproteins. Thus, the determination of riboflavin in food products is essential in riboflavin-fortified foods. However, analysis of riboflavin at natural levels in foods or biological samples is difficult because of its very low concentration level and the presence of undesirable matrix effects which could interfere with the measuring system...
September 14, 2018: Analyst
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