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Nan Wang, Miaomiao Zhang, Xuejuan Chen, Xingxing Ma, Chen Li, Zhe Zhang, Jilin Tang
Mucin 1 (MUC1) is an attractive tumor marker for cancer diagnosis. An advanced atomic force microscopy (AFM) mode, peak-force tapping AFM with an aptamer functionalized tip, was introduced to map the specific interaction sites of an aptamer and MUC1. Single molecular force spectroscopy (SMFS) was used to investigate dynamic parameters of the aptamer-MUC1.
September 20, 2017: Analyst
A D Cabral, B I Murcar-Evans, K Toutah, M Bancerz, D Rosa, K Yuen, T B Radu, M Ali, A Penkul, D Kraskouskaya, P T Gunning
Chemosensors for the detection of phosphate-containing biological species are in high need. Detection of proximally phosphorylated sites of PPi and those found in peptides and proteins has been demonstrated using chemosensors containing pyrene, as a fluorescent reporter, and a Zn(2+)-chelate, as a phosphate-binding group. Using these sensors, detection of proximal phosphate groups is afforded by binding of at least two of the sensor molecules to the adjacent phosphates, via the Zn(2+) centres, leading to excimer formation between the pyrene groups and the corresponding shift in emission from 376 to 476 nm...
September 20, 2017: Analyst
Elizabeth A Jensen, Doug Smith, Patricia Chapela, Susan M Lederer
We discuss and demonstrate why FTIR/ATR spectra can only be calibrated in wavelength, not intensity, for comparison with other data sets at present. This is because the intensity calibration must remove the instrument response function. To address this problem, we suggest a possible approach.
September 18, 2017: Analyst
Zong-Xuan Tong, Wei Liu, Hui Huang, Hong-Zong Chen, Xian-Jun Liu, Yong-Qing Kuang, Jian-Hui Jiang
6-(Diethylamino)-2,3-dihydro-1H-xanthene-4-carbaldehyde (DDXC), a reported synthetic intermediate for near-infrared fluorescent dyes, was developed into a fluorescent pH probe for extreme acidity. The unique sensing mechanism of DDXC for pH is based on the reversible protonation of the carbonyl oxygen followed by keto-enol tautomerization. The probe displays a linear ratiometric fluorescence response (I512/I580) to H(+) over the extremely acidic range of pH 2.0-4.0 with a pKa of 3.11, and features high fluorescence quantum yield (Φ = 0...
September 18, 2017: Analyst
Sian Sloan-Dennison, Stacey Laing, Neil C Shand, Duncan Graham, Karen Faulds
Correction for 'A novel nanozyme assay utilising the catalytic activity of silver nanoparticles and SERRS' by Sian Sloan-Dennison et al., Analyst, 2017, 142, 2484-2490.
September 18, 2017: Analyst
Agnes T Reiner, Nicolas-Guillermo Ferrer, Priyamvada Venugopalan, Ruenn Chai Lai, Sai Kiang Lim, Jakub Dostálek
The sensitive analysis of small lipid extracellular vesicles (EVs) by using a grating-coupled surface plasmon resonance (GC-SPR) biosensor has been reported. In order to enable the analysis of trace amounts of EVs present in complex liquid samples, the target analyte is pre-concentrated on the sensor surface by using magnetic nanoparticles and its affinity binding is probed by wavelength interrogation of SPR. The GC-SPR has been demonstrated to allow for the implementation of efficient pulling of EVs to the sensor surface by using magnetic nanoparticles and an external magnetic field gradient applied through the sensor chip...
September 18, 2017: Analyst
Hongming Yi, Tao Wu, Amélie Lauraguais, Vladimir Semenov, Cecile Coeur, Andy Cassez, Eric Fertein, Xiaoming Gao, Weidong Chen
A spectroscopic instrument based on a mid-infrared external cavity quantum cascade laser (EC-QCL) was developed for high-accuracy measurements of dinitrogen pentoxide (N2O5) at the ppbv-level. A specific concentration retrieval algorithm was developed to remove, from the broadband absorption spectrum of N2O5, both etalon fringes resulting from the EC-QCL intrinsic structure and spectral interference lines of H2O vapour absorption, which led to a significant improvement in measurement accuracy and detection sensitivity (by a factor of 10), compared to using a traditional algorithm for gas concentration retrieval...
September 15, 2017: Analyst
Laura McCann, Tomás E Benavidez, Sarah Holtsclaw, Carlos D Garcia
Adsorption is the most common approach to immobilize biorecognition elements on the surface of paper-based devices. Adsorption is also the route selected to coat the substrate with albumin, therefore minimizing the interaction of other proteins. While similar in nature, the structure of the selected proteins as well as the conditions selected from the immobilization have a significant effect on the amount and distribution of the resulting composites. To illustrate these differences and provide general guidelines to efficiently prepare these devices, this article explores the interaction (adsorption and desorption) of BSA with 3MM chromatography paper...
September 15, 2017: Analyst
Muhammad Ehsan, Lubna Ghani, Yang Du, Parameswaran Hariharan, Jonas S Mortensen, Orquidea Ribeiro, Hongli Hu, Georgios Skiniotis, Claus J Loland, Lan Guan, Brian K Kobilka, Bernadette Byrne, Pil Seok Chae
Integral membrane proteins either alone or as complexes carry out a range of key cellular functions. Detergents are indispensable tools in the isolation of membrane proteins from biological membranes for downstream studies. Although a large number of techniques and tools, including a wide variety of detergents, are available, purification and structural characterization of many membrane proteins remain challenging. In the current study, a new class of tripod amphiphiles bearing two different penta-saccharide head groups, designated TPSs, were developed and evaluated for their ability to extract and stabilize a range of diverse membrane proteins...
September 15, 2017: Analyst
A Menżyk, A Martyna, G Zadora
Polymers have become a ubiquitous element of our culture. Therefore, these materials may play an important role in forensic investigations, serving as mute witnesses of occurrences such as car accidents. In this study, the possibilities provided by the likelihood ratio (LR) approach to estimate the evidential value of observed similarities and differences, and to discriminate among NIR spectral data originating from polypropylene automotive parts and household items, were investigated. Since the construction of LR models requires the introduction of only a few variables, the main objective was to reduce the dimensionality of registered spectra, which are characterised by over a thousand variables...
September 15, 2017: Analyst
Shinichi Komaba, Tatsuya Akatsuka, Kohei Ohura, Chihiro Suzuki, Naoaki Yabuuchi, Shintaro Kanazawa, Kazuhiko Tsuchiya, Taku Hasegawa
All-solid-state ion-selective electrodes as potentiometric ion sensors for lithium, sodium, and potassium have been demonstrated by installing a composite layer containing a powder of alkali insertion materials, LixFePO4, Na0.33MnO2, and KxMnO2·nH2O, respectively, as an inner solid-contact layer between the electrode substrate and plasticized poly(vinyl chloride) (PVC)-based ion-sensitive membrane containing the corresponding ionophores for Li(+), Na(+), and K(+) ions. These double-layer ion-selective electrodes, consisting of the composite and PVC layers prepared by a simple drop cast method, exhibit a quick potential response (less than 5 s) to each alkali-metal ion with sufficient Nernstian slopes of calibration curves, ca...
September 13, 2017: Analyst
Esen Efeoglu, Alan Casey, Hugh J Byrne
Although consumer exposure to nanomaterials is ever increasing, with potential increased applications in areas such as drug and/or gene delivery, contrast agents and diagnosis, the determination of the cyto- and geno-toxic effects of nanomaterials on human health and the environment still remains challenging. Although many techniques have been established and adapted to determine the cytotoxicity and genotoxicity of nano-sized materials, these techniques remain limited by the number of assays required, total cost, and use of labels and they struggle to explain the underlying interaction mechanisms...
September 12, 2017: Analyst
Laura García-Carmona, Daniel Rojas, María Cristina González, Alberto Escarpa
Correction for 'Microchip in situ electrosynthesis of silver metallic oxide clusters for ultra-FAST detection of galactose in galactosemic newborns' urine samples by Laura García-Carmona et al., Analyst, 2016, 141, 6002-6007.
September 12, 2017: Analyst
Øystein Skjærvø, Cecilie Rosting, Trine Grønhaug Halvorsen, Léon Reubsaet
A concept integrating sampling and protein digestion is introduced here combining fast and simple fabrication by wax printing on filter paper with trypsin immobilized polymer beads. The paper reactors showed promising results with a high degree of protein digestion within fifty minutes in model protein mixtures as well as in human blood. The model protein mixture was used for the evaluation of performance both with and without a reduction and alkylation step. The paper reactors without reduction and alkylation showed between 46% and 75% protein sequence coverage and between five and 20 high confidence peptides (one and five zero missed cleavage peptides, respectively)...
September 12, 2017: Analyst
Xia Li, Juan Song, Qingwang Xue, Haiyan Zhao, Min Liu, Baoli Chen, Yun Liu, Wei Jiang, Chen-Zhong Li
Developing a sensitive and selective sensing platform for the p53 gene and its mutation analysis is essential and may aid in early cancer screening and assessment of prognosis. Here, we developed a highly sensitive and selective p53 gene assay based on the coupling of a triple-helix magnetic probe (THMP) to a fluorescent liposome hybridization assembly, a process initiated by rolling circle amplification (RCA). In the presence of p53, the THMP unfolds and activates an enzymatic cleavage reaction, thus releasing the RCA primer and initiating the RCA product-assisted fluorescent liposome hybridization assembly...
September 11, 2017: Analyst
Franck Merlier, Rachid Jellali, Eric Leclerc
A microfluidic liver biochip was coupled with a mass spectrometer to detect in real time the drug metabolism of hepatocytes. The hepatocytes were cultivated in the biochip for 35 h. The biochip was placed in a small-scale incubator in which the temperature and CO2 concentration were controlled. The biochip was connected serially to a mass spectrometer, a peristaltic pump and a culture medium reservoir. The injection in the mass spectrometer was performed every 10 min for 11 h. The metabolism of midazolam, phenacetin, omeprazole, dextromethorphan, repaglinide, rosuvastatin, tolbutamide and caffeine was investigated...
September 11, 2017: Analyst
Hui Liu, Rong Sheng Li, Jun Zhou, Cheng Zhi Huang
N-Acetylcysteine (NAC) plays an important role in optimizing the protective ability of cells as well as in the treatment of some chronic clinical conditions. Unfortunately, current methods for determining NAC based on fluorescence assay strategies remain poorly investigated. In this study, a new fluorescence method for highly sensitive and selective detection of NAC was developed. The detection method employed the fluorescence (FL) signal of branched polyethylenimine-functionalized carbon dots (PEI-CDs) via an off-on mechanism...
September 8, 2017: Analyst
A Murray Booth, Thomas J Bannan, Med Benyezzar, Asan Bacak, M Rami Alfarra, David Topping, Carl J Percival
Lithium ion attachment mass spectrometry provides a non-specific, non-fragmenting, sensitive and robust method for the detection of volatile species in the gas phase. The design, manufacture and results of lithium based ion attachment ionisation sources for two different mass spectrometry systems are presented. In this study trace gas analysis is investigated using a modified Chemical Ionization Mass Spectrometer (CIMS) and vapour pressure measurements are made using a modified Knudsen Effusion Mass Spectrometer (KEMS)...
September 7, 2017: Analyst
Kaili Yang, Min Huo, Yuehua Guo, Yizhuo Yang, Jie Wu, Lin Ding, Huangxian Ju
A target-induced cyclic strategy for DNAzyme formation was proposed to achieve simple, sensitive and universal detection of protein biomarkers with convenient colorimetric or chemiluminescence imaging readout. In the assay, the target protein was recognized by a pair of DNA-labeled antibodies (Ab1-DNA1 and Ab2-DNA2) to form a proximate complex, which could hybridize with the conjugate DNA3/DNA4 to release the guanine-rich DNA4 and thus formed G-quadruplex/hemin horseradish peroxidase-mimicking DNAzyme. The process could be further recycled with Exonuclease III by cleaving DNA3 to free the proximate complex, resulting in the cyclic formation of DNAzyme...
September 7, 2017: Analyst
R J Hopkins, L Lee, N C Shand
Spatially offset Raman spectroscopy (SORS) is a proven technique for sub-surface detection. SORS is able to separate Raman signals from a container and its contents, thereby demonstrating application to through-barrier detection for defence and security. Whilst SORS has been demonstrated to reduce fluorescence from the barrier (or surface), fluorescence from the sample (or sub-surface) can still be problematic for some materials when using Raman excitation wavelengths typical in commercially available instrumentation (e...
September 6, 2017: Analyst
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