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https://www.readbyqxmd.com/read/28524202/association-models-for-binding-of-molecules-to-nanostructures
#1
Manuel Ahumada, Eduardo Lissi, Ana Maria Montagut, Francisco Valenzuela-Henríquez, Natalia L Pacioni, Emilio I Alarcon
The interaction between nanoparticles and molecules plays a key role in determining the activity and performance of a given nanostructure. These interactions are pivotal for a variety of applications including drug delivery, surface manipulation for targeted therapies, and catalysis. However, to this day, gathering precise association parameters for the interaction of the molecules with nanostructures remains elusive and mostly imprecise. In this review, we present a critical discussion of the most commonly used techniques and models intended for determining the association of molecules with nanoparticles...
May 19, 2017: Analyst
https://www.readbyqxmd.com/read/28524193/high-ph-instability-of-quaternary-ammonium-surfactant-coatings-in-capillary-electrophoresis
#2
Lisa Shulman, Lei Pei, Mahmoud F Bahnasy, Charles A Lucy
The two-tailed cationic surfactant dioctadecyldimethyl ammonium bromide (DODAB) produces semi-permanent coatings that yield strongly reversed electroosmotic flow (EOF), for example -0.31 ± 0.01 cm(2) kV(-1) s(-1) at pH 3.5. Moreover, these coatings are easy to prepare, regenerable, cost effective, and yield high efficiency (520 000-900 000 plates per m) separations of cationic proteins over many runs under acidic (pH 3.5) conditions. Given the quaternary amine functionality of DODAB, we were surprised to observe that DODAB coatings become unstable at pH > 7...
May 19, 2017: Analyst
https://www.readbyqxmd.com/read/28524185/erythrocytes-based-quartz-crystal-microbalance-cytosensor-for-in-situ-detection-of-cell-surface-sialic-acid
#3
Xiaojuan Yang, Lin Zhou, Yan Hao, Bin Zhou, Peihui Yang
An erythrocytes (RBCs) cytosensor was first fabricated for in situ analysis of sialic acid (SA) on the cell surface based on a quartz crystal microbalance (QCM). RBCs, as a recognition element, were immobilized on a concanavalin A (ConA)-modified gold chip through the specific recognition between ConA and mannose on the cell surface. 4-Aminobenzeneboronic acid (APBA)-functionalized gold nanoparticles (AuNPs/APBA) were used as a signal amplification nanoprobe for labeling SA on the surface of RBCs. Compared to that of APBA, the frequency response of the cytosensor could be significantly enhanced 18-fold by using a AuNPs/APBA nanoprobe...
May 19, 2017: Analyst
https://www.readbyqxmd.com/read/28518194/detection-of-antibiotic-resistant-escherichia-coli-bacteria-using-infrared-microscopy-and-advanced-multivariate-analysis
#4
Ahmad Salman, Uraib Sharaha, Eladio Rodriguez-Diaz, Elad Shufan, Klaris Riesenberg, Irving J Bigio, Mahmoud Huleihel
Bacterial resistance to antibiotics is becoming a global health-care problem. Bacteria are involved in many diseases, and antibiotics have been the most effective treatment for them. It is essential to treat an infection with an antibiotic to which the infecting bacteria is sensitive; otherwise, the treatment is not effective and may lead to life-threatening progression of disease. Classical microbiology methods that are used for determination of bacterial susceptibility to antibiotics are time consuming, accounting for problematic delays in the administration of appropriate drugs...
May 18, 2017: Analyst
https://www.readbyqxmd.com/read/28516982/colorimetric-and-electrochemical-quantification-of-global-dna-methylation-using-a-methyl-cytosine-specific-antibody
#5
Md Hakimul Haque, Ripon Bhattacharjee, Md Nazmul Islam, Vinod Gopalan, Nam-Trung Nguyen, Alfred K Lam, Muhammad J A Shiddiky
We report a simple colorimetric (naked-eye) and electrochemical method for the rapid, sensitive and specific quantification of global methylation levels using only 25 ng of input DNA. Our approach utilises a three-step strategy; (i) initial adsorption of the extracted, purified and denatured bisulfite-treated DNA on a screen-printed gold electrode (SPE-Au), (ii) immuno-recognition of methylated DNA using a horseradish peroxidase (HRP)-conjugated methylcytosine (HRP-5mC) antibody and (iii) subsequent colorimetric detection by the enzymatic oxidation of 3,3',5,5'-tetramethylbenzidin (TMB)/H2O2 which generated a blue-coloured product in the presence of methylated DNA and HRP-5mC immunocomplex...
May 18, 2017: Analyst
https://www.readbyqxmd.com/read/28516178/a-multi-walled-carbon-nanotube-zinc-oxide-nanofiber-based-flexible-chemiresistive-biosensor-for-malaria-biomarker-detection
#6
Brince Paul K, Asisa Kumar Panigrahi, Vikrant Singh, Shiv Govind Singh
We report the fabrication of a flexible, lightweight and disposable multi walled carbon nanotube (MWCNT)-zinc oxide (ZnO) nanofiber based chemiresistive biosensor for label free detection of the malaria biomarker, histidine rich protein II (HRP2). The sensing platform is formed by depositing nanofibers in between the source and drain electrodes patterned on a thin, flexible polyethylene terephthalate (PET) substrate. MWCNT-ZnO nanofibers are synthesized via the electrospinning technique followed by a calcination process...
May 18, 2017: Analyst
https://www.readbyqxmd.com/read/28513665/a-fully-integrated-microchip-system-for-automated-forensic-short-tandem-repeat-analysis
#7
Junping Han, Wupeng Gan, Bin Zhuang, Jing Sun, Lei Zhao, Jian Ye, Yao Liu, Cai-Xia Li, Peng Liu
We have successfully developed an integrated microsystem that combines two plastic microchips for DNA extraction and PCR amplification with a glass capillary array electrophoresis chip together in a compact control and detection instrument for automated forensic short tandem repeat (STR) analysis. DNA extraction followed by an "in situ PCR" was conducted in a single reaction chamber of the microchip based on a filter paper-based extraction methodology. PCR products were then mixed with sizing standards by an injection electrode and injected into the electrophoresis chip for four-color confocal fluorescence detection...
May 17, 2017: Analyst
https://www.readbyqxmd.com/read/28513658/capillary-zone-electrophoresis-mass-spectrometry-with-microliter-scale-loading-capacity-140-min-separation-window-and-high-peak-capacity-for-bottom-up-proteomics
#8
Daoyang Chen, Xiaojing Shen, Liangliang Sun
Better peptide separation is required for bottom-up proteomics for further improving the proteome coverage. The two-dimensional liquid chromatography (2D-LC) systems only explore differences among peptides in their hydrophobicity (reversed-phase, RP) and charge (strong cation/anion exchange, SCX/SAX). Alternative separation techniques with different separation mechanisms are required to further improve the separation. Capillary zone electrophoresis (CZE) is an attractive alternative because it has high efficiency for separation of biomolecules and it separates analytes based on their size-to-charge ratios, complementary with LC...
May 17, 2017: Analyst
https://www.readbyqxmd.com/read/28513652/an-electrochemiluminescence-assay-for-sensitive-detection-of-methyltransferase-activity-in-different-cancer-cells-by-hybridization-chain-reaction-coupled-with-a-g-quadruplex-hemin-dnazyme-biosensing-strategy
#9
Hui Zhang, Zhihui Guo, Huilei Dong, Hongfei Chen, Chenxin Cai
In this work, a highly sensitive electrochemiluminescence (ECL) assay was fabricated for the detection of human DNA (cytosine-5)-methyltransferase1 (DNMT1) activity in cancer cells. The ECL assay coupled hybridization chain reaction with a G-quadruplex/hemin DNAzyme biosensing strategy. The ECL intensity changes (ΔI) allowed detection of DNMT1 activity down to 0.09 U mL(-1), and ΔI was proportional to the logarithm of the activity of DNMT1 within the range of 1.0 to 30.0 U mL(-1) in buffer solution. It also showed high sensitivity to DNMT1 activity in A549 cells, with a detection limit of about 2 cells...
May 17, 2017: Analyst
https://www.readbyqxmd.com/read/28513638/automatic-assignment-of-metal-containing-peptides-in-proteomic-lc-ms-and-ms-ms-data-sets
#10
Christopher A Wootton, Yuko P Y Lam, Matthew Willetts, Maria A van Agthoven, Mark P Barrow, Peter J Sadler, Peter B O Connor
Transition metal-containing proteins and enzymes are critical for the maintenance of cellular function and metal-based (metallo)drugs are commonly used for the treatment of many diseases, such as cancer. Detection and characterisation of metallodrug targets is crucial for improving drug-design and therapeutic efficacy. Due to the unique isotopic ratios of many metal species, and the complexity of proteomic samples, standard MS data analysis of these species is unsuitable for accurate assignment. Herein a new method for differentiating metal-containing species within complex LCMS data is presented based upon the Smart Numerical Annotation Procedure (SNAP)...
May 17, 2017: Analyst
https://www.readbyqxmd.com/read/28509933/combined-use-of-afm-and-soft-x-ray-microscopy-to-reveal-fibres-internalization-in-mesothelial-cells
#11
Alessandra Gianoncelli, George Kourousias, Francesca Cammisuli, Damiano Cassese, Clara Rizzardi, Oriano Radillo, Marco Lazzarino, Lorella Pascolo
Nanotoxicology and nanomedicine investigations often require the probing of nano-objects such as fibres and particles in biological samples and cells, whilst internalization and intracellular destiny are the main issues for in vitro cellular studies. Various high resolution microscopy techniques are well suited for providing this highly sought-after information. However, sample preparation, nanomaterial composition and sectioning challenges make it often difficult to establish whether the fibres or particles have been internalized or they are simply overlaying or underlying the biological matter...
May 16, 2017: Analyst
https://www.readbyqxmd.com/read/28509920/insights-into-chemoselectivity-principles-in-metal-oxide-affinity-chromatography-using-tailored-nanocast-metal-oxide-microspheres-and-mass-spectrometry-based-phosphoproteomics
#12
Alexander Leitner, Motolani Sakeye, Christian Eugen Zimmerli, Jan-Henrik Smått
The ability to comprehensively characterize biological samples, including tissues and body fluids, opens up new possibilities to diagnose and treat diseases and to better understand fundamental biological processes. For this purpose, suitable experimental workflows need to be designed. In this context, materials with particular chemoselective properties are used for the enrichment of certain classes of (bio)molecules. Metal oxides such as titanium dioxide have become the materials of choice for the large-scale study of protein phosphorylation in phosphoproteomics...
May 16, 2017: Analyst
https://www.readbyqxmd.com/read/28504795/label-free-detection-of-dna-hybridization-with-a-compact-lspr-based-fiber-optic-sensor
#13
Savannah Kaye, Zheng Zeng, Mollye Sanders, Krishnan Chittur, Paula M Koelle, Robert Lindquist, Upender Manne, Yongbin Lin, Jianjun Wei
A miniaturized, robust, localized surface plasmon resonance (LSPR)-coupled fiber-optic (FO) nanoprobe providing an integrated and portable solution for detection of DNA hybridization and measurement of DNA concentrations has been demonstrated. The FO nanoprobe was created by constructing arrays of metallic nanostructures on the end facets of optical fibers utilizing nanofabrication technologies, including electron beam lithography and lift-off processes. The LSPR-FO nanoprobe device offers real-time, label-free, and low-sample-volume quantification of single-strand DNA in water with high sensitivity and selectivity, achieving a limit of detection around 10 fM...
May 15, 2017: Analyst
https://www.readbyqxmd.com/read/28503694/detection-of-early-osteogenic-commitment-in-primary-cells-using-raman-spectroscopy
#14
Stephanie J Smith, Roger Emery, Andrew Pitsillides, Claire E Clarkin, Sumeet Mahajan
Major challenges in the development of novel implant surfaces for artificial joints include osteoblast heterogeneity and the lack of a simple and sensitive in vitro assay to measure early osteogenic responses. Raman spectroscopy is a label-free, non-invasive and non-destructive vibrational fingerprinting optical technique that is increasingly being applied to detect biochemical changes in cells. In this study Raman spectroscopy has been used to obtain bone cell-specific spectral signatures and to identify any changes therein during osteoblast commitment and differentiation of primary cells in culture...
May 15, 2017: Analyst
https://www.readbyqxmd.com/read/28503691/a-rapidly-prototyped-microfluidic-device-for-size-based-nucleic-acid-fractionation-using-isotachophoresis
#15
C Eid, S S Branda, R J Meagher
We present a novel microfluidic device for size-based nucleic acid (NA) fractionation using isotachophoresis (ITP) and an ionic spacer. Our rapid-prototyped laser-cut plastic device has easily modifiable channel dimensions, can process up to 10 μL of sample, and contains an in-line extraction reservoir for minimally-disruptive manual collection of size-fractionated NAs. We designed custom buffering reservoirs using 1 mL pipette tips to provide high buffering capacity and prevent bubbles from entering the microfluidic channels...
May 15, 2017: Analyst
https://www.readbyqxmd.com/read/28497155/influence-of-washing-and-quenching-in-profiling-the-metabolome-of-adherent-mammalian-cells-a-case-study-with-the-metastatic-breast-cancer-cell-line-mda-mb-231
#16
Rahul Vijay Kapoore, Rachael Coyle, Carolyn A Staton, Nicola J Brown, Seetharaman Vaidyanathan
Metabolome characterisation is a powerful tool in oncology. To obtain a valid description of the intracellular metabolome, two of the preparatory steps are crucial, namely washing and quenching. Washing must effectively remove the extracellular media components and quenching should stop the metabolic activities within the cell, without altering the membrane integrity of the cell. Therefore, it is important to evaluate the efficiency of the washing and quenching solvents. In this study, we employed two previously optimised protocols for simultaneous quenching and extraction, and investigated the effects of a number of washing steps/solvents and quenching solvent additives, on metabolite leakage from the adherent metastatic breast cancer cell line MDA-MB-231...
May 12, 2017: Analyst
https://www.readbyqxmd.com/read/28492640/impedimetric-measurement-of-dna-dna-hybridisation-using-microelectrodes-with-different-radii-for-detection-of-methicillin-resistant-staphylococcus-aureus-mrsa
#17
Poh Quan Li, Andrew Piper, Ilka Schmueser, Andrew R Mount, Damion K Corrigan
Due to their electroanalytical advantages, microelectrodes are a very attractive technology for sensing and monitoring applications. One highly important application is measurement of DNA hybridisation to detect a wide range of clinically important phenomena, including single nucleotide polymorphisms (SNPs), mutations and drug resistance genes. The use of electrochemical impedance spectroscopy (EIS) for measurement of DNA hybridisation is well established for large electrodes but as yet remains relatively unexplored for microelectrodes due to difficulties associated with electrode functionalisation and impedimetric response interpretation...
May 11, 2017: Analyst
https://www.readbyqxmd.com/read/28487922/microscopic-evaluation-of-aqueous-two-phase-system-emulsion-characteristics-enables-rapid-determination-of-critical-polymer-concentrations-for-solution-micropatterning
#18
Mackenzie Ruthven, Kristin Robin Ko, Rishima Agarwal, John P Frampton
Aqueous two-phase systems have emerged as valuable tools for microscale analysis of cell growth and many other biotechnology applications. The most critical step in developing an aqueous two-phase system for a specific application is identifying the critical concentrations at which the polymer solutions phase-separate. Current techniques for determining these critical concentrations rely on laborious methods, highly specialized assays or computational methods that make this step difficult for non-specialists...
May 10, 2017: Analyst
https://www.readbyqxmd.com/read/28487921/triplex-hybridizing-bioconjugated-gold-nanoparticles-for-specific-y-chromosome-sequence-targeting-of-bull-spermatozoa
#19
L Gamrad, R Mancini, D Werner, D Tiedemann, U Taylor, A Ziefuß, C Rehbock, S Klein, W Kues, S Barcikowski, D Rath
Gold nanoparticles (AuNPs) are widely used in biomedical applications for drug targeting and bioimaging. This often neccesitates their functionalization with biomolecules carrying a defined biological function, yielding gold nanoparticle bioconjugates. The utilization of triplex-forming oligonucleotides (TFOs) as ligands gives access to nanoconjugates as tools for specific DNA-related nanotargeting via triplex hybridization. Since triplex hybridization with nanobioconjugates has to date not been shown on biologically relevant samples, sex-specific sperm marking may be an appropriate model system to demonstrate the opportunities of this targeting method in vitro...
May 10, 2017: Analyst
https://www.readbyqxmd.com/read/28487913/recent-developments-in-protease-activity-assays-and-sensors
#20
REVIEW
Irvine Lian Hao Ong, Kun-Lin Yang
Proteases play a pivotal role in regulating important physiological processes from food digestion to blood clotting. They are also important biomarkers for many diseases such as cancers. The importance of proteases has led to extensive efforts in the screening of proteases and their inhibitors as potential drug molecules. For example, human immunodeficiency virus (HIV) patients have been treated with HIV-1 protease inhibitors to prolong the life expectancy of patients. Such a close relationship between diseases and proteases provides a strong motivation for developing sensitive, selective, and robust protease assays and sensors, which can be exploited to discover new proteases and inhibitors...
May 10, 2017: Analyst
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