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Andrew G Elliott, Conner C Harper, Haw-Wei Lin, Evan R Williams
Charge detection mass spectrometry is used to measure the mass, charge, MS(n) and mobility of an individual ion produced by electrospray ionization of a 8 MDa polyethylene glycol sample. The charge detection mass spectrometer is an electrostatic ion trap that uses cone electrodes and a single tube detector and can detect ions for up to the full trapping time of 4.0 s. The time-domain signal induced on the detector tube by a single multiply charged ion can be complex owing to sequential fragmentation of the original precursor ion as well as increasing oscillation frequencies of the single ion owing to collisions with background gas that reduce the kinetic energy of the ion inside the trap...
June 21, 2017: Analyst
Yueming Hu, Chad R Borges
Glycan permethylation was introduced as a tool to facilitate the study of glycans in 1903. Since that time, permethylation procedures have been continually modified to improve permethylation efficiency and qualitative applicability. Typically, however, either laborious preparation steps or cumbersome and uneconomical spin columns have been needed to obtain decent permethylation yields on small glycan samples. Here we describe a spin column-free (SCF) glycan permethylation procedure that is applicable to both O- and N-linked glycans and can be employed upstream to intact glycan analysis by MALDI-MS, ESI-MS, or glycan linkage analysis by GC-MS...
June 21, 2017: Analyst
Nivedita Nivedita, Neha Garg, Abraham P Lee, Ian Papautsky
Numerous applications in biology and medicine require the efficient and reliable separation of cells for disease diagnosis, genetic analysis, drug screening, and therapeutics. In this work, we demonstrate a novel technology that integrates a passive and an active device to separate, enrich and release cells on-demand from a complex blood sample, or cancer cells derived from a tissue biopsy. We exploit the high throughput (>1 mL min(-1)), size-based sorting capability of the passive spiral inertial microfluidic (iMF) device to focus particles/cells towards an active lateral cavity acoustic transducer (LCAT) device for size-selective enrichment...
June 21, 2017: Analyst
Yale Wu, Tao Yang, Kuo-Chih Chou, Junhong Chen, Lei Su, Xinmei Hou
A platform for the simultaneous determination of Cd(ii) and Pb(ii) in aqueous solution has been applied based on an aluminum silicon carbide-reduced graphene oxide nanocomposite (Al4SiC4-RGO) modified bismuth film glassy carbon electrode (GCE) using square wave anodic stripping voltammetry (SWASV) for the first time. The Al4SiC4-RGO nanocomposite electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the Al4SiC4 modified GCE and bare GCE, the electrochemical performance of the Al4SiC4-RGO nanocomposite electrode is obviously enhanced resulting from the synergistic effects of Al4SiC4, RGO and bismuth film...
June 16, 2017: Analyst
Lee Chuin Chen, Tsubasa Naito, Satoru Tsutsui, Yuki Yamada, Satoshi Ninomiya, Kentaro Yoshimura, Sen Takeda, Kenzo Hiraoka
At present, endoscopy relies almost exclusively on optical microscopy and the accurate analysis such as MS interrogation is performed ex situ using biopsy. In this work, a novel probing system is developed to perform in situ and in vivo endoscopic mass spectrometry using a moving string for the sampling and transportation of material. A prototype of a mass spectrometric endoscope is constructed using an industrial endoscope and a commercial mass spectrometer. The sampling system consists of a moving cotton thread driven by motorized pulleys...
June 15, 2017: Analyst
K Lipponen, S Tähkä, T Sikanen, V Jokinen, A Tatikonda, S Franssila, R Kostiainen, T Kotiaho
A micropillar array electrospray ionization (μPESI) platform fabricated from thiol-enes with 56 individual polyethylene glycol coated μPESI chips for bioanalytical mass spectrometry is introduced. Bioanalysis capability is shown by measurement of a protein, a protein digest and a cell lysate sample. The thiol-ene polyethylene glycol (PEG) coated μPESI chip allows the use of a wide range of aqueous-organic solvent compositions and provides a detection limit at 60 zeptomole level (6 × 10(-20) mol) for a peptide standard...
June 15, 2017: Analyst
Miriam Schwamborn, Johannes Schumacher, Jeremias Sibold, Nikolas K Teiwes, Claudia Steinem
Monitoring the proton pumping activity of proteins such as ATPases in reconstituted single proteoliposomes is key to quantify the function of proteins as well as potential proton pump inhibitors. However, most pH-detecting assays available are either not quantitative, require well-adapted reconstitution protocols or are not appropriate for single vesicle studies. Here, we describe the quantitative and time-resolved detection of F-type ATPase-induced pH changes across vesicular membranes doped with the commercially available pH sensitive fluorophore Oregon Green 488 DHPE...
June 15, 2017: Analyst
Jiaoe Yang, Liuying He, Yuexiang Lu, Xinxin Gao, Feiyang Wang, Wenjie Jing, Yueying Liu
The development of sensitive and cheap sensor arrays for identification of proteins plays an important role in many bioanalytical and clinical investigations. Here, we introduce a multidimensional colorimetric sensor array for the detection of multiple proteins based on acquiring multiple signals along with the reaction time to enhance the discrimination ability. In a single experiment, the unique fingerprint for each protein against the sensor array is generated from a response absorbance signal at three reaction time points (at 10 min, 15 min, and 20 min)...
June 15, 2017: Analyst
Stefanie Kirschbaum-Harriman, Axel Duerkop, Antje J Baeumner
The influence of surfactants and coreactants on Ru(bpy)3(2+) electrogenerated chemiluminescence (ECL) was investigated comparatively. Specifically, the influence that the two tertiary amines, N-butyldiethanolamine (NBEA) and 2-(dibutylamino)ethanol (DBAE) have on the ECL reaction, alone and in the presence of the two surfactants Triton™ X-100 and Zonyl® FSN, was investigated, in comparison with that of the well-studied and established coreactant tripropylamine (TPA). Experiments were conducted on poly(methyl methacrylate) substrates coated with plasma-evaporated gold as used in many miniaturized systems...
June 14, 2017: Analyst
Xiaolin Cao, Sihui Hong, Zejun Jiang, Yongxin She, Shanshan Wang, Chan Zhang, Hui Li, Fen Jin, Maojun Jin, Jing Wang
Surface-enhanced Raman scattering (SERS) has been widely used in the detection of targets and strongly depends on the interaction and the distance between the targets and nanoparticles. Herein, metal-organic frameworks (MOFs) were first easily synthesized on a large scale via a water bath method, especially Uio-66 and Uio-67. MOFs embedded with gold nanoparticles (AuNPs) for SERS enhancement were successfully fabricated via an impregnation strategy. The synthesized AuNPs/MOF-199, AuNPs/Uio-66, and AuNPs/Uio-67 composites, with LSPR properties and high adsorption capability of MOFs to preconcentrate the analytes close to the surface of the AuNPs, exhibited excellent SERS activity...
June 14, 2017: Analyst
Congcong Wu, Zhaomei Sun, Li-Shang Liu
The surface crystallization of CaCO3 on gold was monitored by a quartz crystal microbalance (QCM). Quantitative control of the grown crystals was realized by adjusting the ratio of two functional groups, -N(CH3)3 and -COOH, on SAMs. Crystals with uniform size, morphology and polymorphism were obtained. The amount of crystals formed was found to increase with an increase in the -COOH group. The proposed quantitative control of crystallization can be an effective mass amplification strategy for QCM to enhance its assay sensitivity...
June 14, 2017: Analyst
Lothar Veith, Antje Vennemann, Daniel Breitenstein, Carsten Engelhard, Martin Wiemann, Birgit Hagenhoff
The direct detection of nanoparticles in tissues at high spatial resolution is a current goal in nanotoxicology. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is widely used for the direct detection of inorganic and organic substances with high spatial resolution but its capability to detect nanoparticles in tissue sections is still insufficiently explored. To estimate the applicability of this technique for nanotoxicological questions, comparative studies with established techniques on the detection of nanoparticles can offer additional insights...
June 13, 2017: Analyst
Dan Pan, Fengyan Luo, Xianjun Liu, Wei Liu, Wen Chen, Feng Liu, Yong-Qing Kuang, Jian-Hui Jiang
In recent years, many activatable fluorescent probes have been developed for hNQO1 detection. However, most of the reported fluorescent probes are susceptible to the interferences of endogenous fluorescence and have the drawback of inadequate penetration depth. Very recently, researchers have reported a two-photon excitation (TPE) fluorescent probe for hNQO1 detection. Nevertheless, this probe only exhibits a compromised signal-to-background ratio, and has not been applied to image hNQO1 in living tissues. Herein, a novel TPE fluorescent probe, trimethyl locked quinone caged Acedan (Q3CA-P), has been developed for hNQO1 detection and imaging in living cells and tissues...
June 13, 2017: Analyst
Yan Xiao, Yuhao Sheng, Jie Zhou, Miaomiao Chen, Wei Wen, Xiuhua Zhang, Shengfu Wang
Graphitic carbon nitride (g-C3N4) nanosheets are a type of two-dimensional nanomaterial with stable photoluminescence and large specific surface areas that make them an ideal candidate for fluorescence sensing. However, fluorescence sensing based on g-C3N4 nanosheets for disease-specific biomolecules is still limited. Moreover, current g-C3N4 nanosheet-based fluorescence sensors for nucleic acid require pre-labeling which is time-consuming and cost-ineffective. In this work, a novel label-free strategy for HBV gene determination based on metal ion binding-induced fluorescence quenching of g-C3N4 nanosheets was designed...
June 13, 2017: Analyst
Jinlan Dong, Wenjing Ning, Weijing Liu, Merlin L Bruening
Proteolysis is often a critical step in protein characterization via mass spectrometry. Compared to complete digestion, limited proteolysis gives larger peptides, and the dominant cleavage sites may identify highly accessible, flexible protein regions. This paper explores controlled proteolysis in porous nylon membranes containing immobilized trypsin. Passage of protein solutions through ∼100 μm thick membranes provides reaction residence times as short as milliseconds to limit digestion. Additionally, variation of the membrane pore size and the protease-immobilization method (electrostatic adsorption or covalent anchoring to adsorbed polymer in membrane pores) affords control over the proteolysis rate...
June 13, 2017: Analyst
Jae-Won Choi, Bala Murali Krishna Vasamsetti, Kyu-Wan Kim, Seung Hwan Seo, Dong-Hun Lee, Soo-Ik Chang, Jaebum Choo, Hak Yong Kim
We report the results of a label-free analysis of ribonuclease activity using droplet-based microfluidics. The ribonucleolytic activity of ribonucleases (RNases) plays a critical role in cellular functions such as development, survival, growth and differentiation. Altered ribonucleolytic activity and/or the expression level of the RNase A family are known to be associated with pancreatic, bladder, ovarian and thyroid cancers among others. For this reason, the RNase A family is a meaningful protein biomarker that can be used in the diagnosis of cancer and as a target for new drug screening...
June 12, 2017: Analyst
Debora Bonvin, Heinrich Hofmann, Marijana Mionić Ebersold
We developed a method to correct absorbance-based toxicity tests to remove the influence of the deposited dose of nanoparticles. As a model of absorbance-based toxicity tests, we chose the frequently used MTS test. The corrected cell viabilities obtained with the MTS test matched the results of the fluorescence-based PrestoBlue® test.
June 12, 2017: Analyst
Tongrui Zhang, Mengjun Liu, Qianqian Zhang, Yeyu Wang, Xiangyi Kong, Lei Wang, Huan Wang, Yufan Zhang
A simple and sensitive electrochemical sensor is constructed for the detection of chlorogenic acid (CGA) based on Au nanoparticles (NPs)/polyoxometalates/3D macroporous carbon (Au-POMs-MPC). Serving as both a reducing and stabilizing agent, the Keggin-type POM, H3PW12O40, is used for the synthesis of stable colloidal Au NPs and then used to link them to MPC at a mild temperature. Because of the unique structural properties and synergetic catalytic effect, Au-POMs-MPC can be developed as an effective sensing platform for the detection of CGA, which showed high activity and excellent analytical performance towards CGA, such as a wide linear range of 2...
June 12, 2017: Analyst
Sian Sloan-Dennison, Stacey Laing, Neil C Shand, Duncan Graham, Karen Faulds
Artificial enzymes have become an increasingly interesting area of research due to their many advantages over natural protein enzymes which are expensive, difficult to isolate and unable to stand harsh environments. An important area of this research involves using metal nanoparticles as artificial enzymes, known as nanozymes, which exhibit peroxidase-like activity enabling them to catalyse the oxidation of substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2), giving a colorimetric response...
June 12, 2017: Analyst
Bal-Ram Adhikari, Heidi Schraft, Aicheng Chen
Entrapment is one of the major approaches for enzyme immobilization; however, it suffers a few critical drawbacks including leakage and high mass transfer resistance to substrates. To address these challenges, herein we report on a new facile and effective enzyme entrapment platform using a special cationic polymer, poly(2-(dimethylamino)ethyl methacrylate) (MADQUAT) on a single-wall carbon nanotube and reduced graphene oxide (SWCNT-rGO) nanohybrid thin film. To demonstrate this new approach, alcohol dehydrogenase (ADH) is employed as a model enzyme for the entrapment toward the design of an efficient electrochemical biosensor for the detection of ethanol...
June 9, 2017: Analyst
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