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Xueping Zhang, Qingqing Wang, Jing Li, Liang Huang, Dengbin Yu, Shaojun Dong
In this work, a novel electrochemical sensor for Cd(ii) detection with differential pulse anodic stripping voltammetry (DPASV) is fabricated based on hollow ZnO@nitrogen-doped carbon (H-ZnO@NC) polyhedra, which are prepared from ZIF-8 via in situ tannic acid etching and a subsequent calcination process. The as-obtained H-ZnO@NC exhibits a polyhedral morphology with a well-defined hollow structure and a uniform distribution of elements C, N, O, and Zn in the shell. The unique structure of H-ZnO@NC can provide an enlarged surface area and abundant active sites...
May 22, 2018: Analyst
Michael Woolman, Arash Zarrine-Afsar
Ambient Mass Spectrometry (MS) analysis is widely used to characterize biological and non-biological samples. Advancements that allow rapid analysis of samples by ambient methods such as Desorption Electrospray Ionization Mass Spectrometry (DESI-MS) and Rapid Evaporative Ionization Mass Spectrometry (REIMS) are discussed. A short, non-comprehensive overview of ambient MS is provided that only contains example applications due to space limitations. A spatially encoded mass spectrometry analysis concept to plan cancer resection is introduced...
May 22, 2018: Analyst
Ajar Kamal, Renu Sharma, Zhe She, Heinz-Bernhard Kraatz
Hg(ii) binding to thymine-rich oligonucleotides (ODNs) is investigated electrochemically. The focus of this study is to probe the effects of position on the electrochemical response. For this purpose, three oligonucleotides were investigated in which the position of a hexa-thymine repeat is varied within a surface-supported oligonucleotide. The hexa repeats were placed in the top, middle, and bottom positions within the strand with respect to the gold surface. The effects were monitored by electrochemical impedance spectroscopy and scanning electrochemical microscopy...
May 22, 2018: Analyst
Zhi Liu, Zhiguo Qu, Ruihua Tang, Xiaocong He, Hui Yang, Dan Bai, Feng Xu
Lateral flow assays (LFAs) have attracted considerable attention in biomedical diagnostics. However, it's still challenging to achieve a high detection sensitivity and extensive working range, mainly because the underlying mechanism of complex reaction processes in LFAs remains unclear. Many mathematical models have been developed to analyze the complex reaction processes, which are only qualitative with limited guidance for LFA design. Now, a semi-quantitative convection-diffusion-reaction model is developed by considering the kinetics of renaturation of nucleic acids and the model is validated by our experiments...
May 21, 2018: Analyst
Samantha A Byrnes, Elizabeth A Phillips, Toan Huynh, Bernhard H Weigl, Kevin P Nichols
Microbiological culture remains the most sensitive method for detecting viable and infectious bacteria, but these methods often require at least 24 hours to visibly identify bacterial growth. Lab-on-a-chip applications have utilized methods to isolate bacteria in picoliter-sized reaction vessels, resulting in digitized signals that offer improved time-to-detection and improved quantification. Although a great improvement, these approaches typically require expensive and specialized equipment, trained laboratory personnel, and maximum addressable volumes that can be orders of magnitude less than needed for clinically relevant limits of detection...
May 21, 2018: Analyst
Joseph D Kimball, Badri Maliwal, Sangram L Raut, Hung Doan, Zhangatay Nurekeyev, Ignacy Gryczynski, Zygmunt Gryczynski
Fluorescence signal enhancement induced by the binding of intercalators to DNA has been broadly utilized in various DNA detection methods. In most instances the increase in fluorescence intensity is associated with a concomitant increase of fluorescence lifetime. This increase of the fluorescence lifetime presents an additional opportunity to increase detection sensitivity. In this paper, we present a new approach to significantly enhance the sensitivity in detecting minute DNA concentrations. The approach is based on simultaneous use of time-gated detection and multi-pulse pumping...
May 18, 2018: Analyst
Lingying Zhou, Ning Gan, Yongxiang Wu, Futao Hu, Jianyuan Lin, Yuting Cao, Dazhen Wu
Recently, it has been crucial to be able to detect and quantify small molecular targets simultaneously in biological samples. Herein, a simple and conventional double-T type microchip electrophoresis (MCE) based platform for the multiplex detection of quality indicator molecule targets in urine, using ampicillin (AMPI), adenosine triphosphate (ATP) and estradiol (E2) as models, was developed. Several programmable hairpin probes (PHPs) were designed for detecting different targets and triggering isothermal polymerase-catalyzed target recycling (IPCTR) for signal amplification...
May 18, 2018: Analyst
Xiaonan Cui, Lihui Ren, Yufei Shan, Xixian Wang, Zhenlong Yang, Chunyu Li, Jian Xu, Bo Ma
Standard plate count (SPC) has been recognized as the golden standard for the quantification of viable bacteria. However, SPC usually takes one to several days to grow individual cells into a visible colony, which greatly hampers its application in rapid bacteria enumeration. Here we present a microdroplet turbidity imaging based digital standard plate count (dSPC) method to overcome this hurdle. Instead of cultivating on agar plates, bacteria are encapsulated in monodisperse microdroplets for single-cell cultivation...
May 18, 2018: Analyst
Mauro Safir Filho, Pascal Dao, Maéva Gesson, Anthony R Martin, Rachid Benhida
We report the development of four novel fluorescent probes to monitor the activity of the β-galactosidase enzyme (β-gal), in vitro and in living cells. The fluorophores are based on a 6-amino-styryl-benzothiazole push-pull core and display a strong ICT emission. The probes encompass the fluorescent motif that is connected to a β-d-galactopyranoside moiety through a self-immolative benzyl carbamate linker (βGal-1-4). The screening of four different fluorophores enabled us to access new light-up and two-band ratiometric reporters...
May 18, 2018: Analyst
X Luo, M Huang, D He, M Wang, Y Zhang, P Jiang
High electrical conductivity and the exposure to more active sites are crucial to boost the performance of a glucose sensor. A porous binary metal oxide nanoarray integrated on a binder-free 3D electrode is expected to offer a highly sensitive sensing platform. As a model, porous NiCo2O4 nanowire arrays supported on carbon cloth (NiCo2O4 NWA/CC) have been prepared and used for enzyme-free glucose sensing. NiCo2O4 NWA/CC shows larger effective surface area, superior electronic conductivity, and higher catalytic activity towards enzyme-free glucose sensing, with a linear range from 1 μM to 0...
May 18, 2018: Analyst
Ichiro Tanabe, Aki Suyama, Taiki Sato, Ken-Ichi Fukui
Despite providing rich information on electronic states, the far-ultraviolet (FUV, <200 nm) and deep-ultraviolet (DUV, <300 nm) absorption spectra of ionic liquids (ILs) are difficult to obtain without saturation due to very strong analyte absorbance. Herein, FUV-DUV spectra of selected ILs were systematically and easily recorded using an attenuated total reflectance spectrometer and rationalized based on quantum chemical calculations. ILs containing pyrrolidinium or ammonium cations and fluorine-containing anions exhibited weak absorbance below 200 nm that could not be measured by conventional UV-Vis spectroscopy, whereas the corresponding imidazolium-based ILs showed distinct absorption bands that could be reproduced by single-cation-model calculations...
May 17, 2018: Analyst
Jianyu Zhou, Tao Dong
In this study, we developed a novel wearable and low-cost device for qualitative screening of glucose (GLU), leukocytes (LEU), and nitrite (NIT) and for semi-quantitative analysis of blood (BLD) and proteins (PRO) in the urine samples. The device can be attached to a diaper, and the results can be read by an app. The main functions of the device can be divided into sample collection, valve closing, and pad saturation; the recorded times for valve closing and pad saturation at four corners and pad saturation at the central parts are pseudo-medians (Hodges-Lehmann estimator) of 3...
May 16, 2018: Analyst
Vitaly I Korepanov, Daria M Sedlovets
Asymmetric lineshapes are experimentally observed in the Raman spectra of different classes of condensed matter. Determination of the peak parameters, typically done with symmetric pseudo-Voigt functions, in such situations yields unreliable results. While a wide choice of asymmetric fitting functions is possible, for the function to be practically useful, it should satisfy several criteria: simple analytic form, minimum parameters, description of the symmetric shape as "zero case", estimation of the desired peak parameters in a straightforward way and, above all, adequate description of the experimental data...
May 15, 2018: Analyst
Ji Sun, Lin Gong, Yuntao Lu, Dongmei Wang, Zhengjun Gong, Meikun Fan
In this study, a versatile dual-functional polydimethylsiloxane (PDMS) sponge Surface Enhanced Raman Scattering (SERS) substrate has been fabricated for the on-site detection of pesticide residues both on the surface and in solution with minimum or no sample pretreatment. The PDMS sponge was fabricated using white granulated sugar and soft white sugar as pore-forming reagents. Later, multiple rounds of Ag NP deposition were performed by incubating the PDMS sponge in the Ag NP solution with the help of 3-mercaptopropyltrimethoxysilane (APTMS)...
May 15, 2018: Analyst
Xiaojuan Deng, Wenbin Li, Guosheng Ding, Xiaoping Chen
Chiral magnetic microspheres show great potential in direct enantioseparation. Herein novel chiral magnetic microspheres were prepared by self-assembling β-cyclodextrin on magnetic Fe3O4@SiO2/Au composite microspheres. The prepared materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), vibrating sample magnetometry (VSM) and Fourier transform infrared spectroscopy (FTIR). The results showed that the functional microspheres have a three-ply structure and high saturation magnetization...
May 15, 2018: Analyst
Y W Jia, S Y Sun, L Yang, D Wang
An algorithm for signal extraction from a contaminated and distorted spectrum is proposed. First, this algorithm combines the salient space of the spectrum and the statistical characteristics of the noise to detect signal regions at different scales. Second, it extracts signals by subtracting the baseline from the spectrum in the signal regions. The baseline is fitted by segmented polynomial functions. This algorithm has been applied to simulated and experimental data, and the results show that this algorithm can accurately and automatically extract signals with varying widths from a contaminated spectrum...
May 14, 2018: Analyst
Xiaoyi Wang, Jie Min, Weijie Wang, Yan Wang, Gui Yin, Ruiyong Wang
Reactive oxygen species (ROS), especially HOCl/ClO-, have been demonstrated to play essential roles in both physiological and pathological processes, and an abnormal level of HOCl/ClO- is related to some diseases. In this work, a very fast responsive (within 30 seconds) porphyrin-based fluorescent probe, TPP-TCF, for ClO- with a NIR emissive wavelength was prepared. This probe exhibited excellent selectivity towards ClO- and would not be interfered with by other ROS and typical nucleophiles. The limit of detection (LOD) for ClO- was evaluated to be 0...
May 14, 2018: Analyst
Andrey Coatrini Soares, Juliana Coatrini Soares, Flavio Makoto Shimizu, Valquiria da Cruz Rodrigues, Iram Taj Awan, Matias Eliseo Melendez, Maria Helena Oliveira Piazzetta, Angelo Luiz Gobbi, Rui Manuel Reis, José Humberto T G Fregnani, André Lopes Carvalho, Osvaldo N Oliveira
The challenge of the early diagnosis of pancreatic cancer in routine clinical practice requires low-cost means of detection, and this may be achieved with immunosensors based on electrical or electrochemical principles. In this paper, we report a potentially low-cost immunosensor built with interdigitated gold electrodes coated with a self-assembled monolayer and a layer of anti-CA19-9 antibodies, which is capable of detecting the pancreatic cancer biomarker CA19-9 using electrical impedance spectroscopy. Due to specific, irreversible adsorption of CA19-9 onto its corresponding antibody, according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), the immunosensor is highly sensitive and selective...
May 14, 2018: Analyst
M Gast, S Kühner, H Sobek, B Mizaikoff
In the present study, virus imprinted particles have been synthesized for recognizing and specifically binding viruses. These materials may be used for biomimetic sensing schemes and for selective removal of virus particles. Virus imprinting procedures require careful optimization of the synthesis route for obtaining selective and efficiently binding imprinted materials. A remaining limitation has been a facile method for the quantification of the viral load during the imprinting process. Herein, human adenovirus (AdV) was selected as a model virus facilitating the development and application of a rapid virus quantification method based on a molecular biological approach...
May 14, 2018: Analyst
A R Ghiasvand, N Heidari, S Abdolhosseini, A Hamdi, P R Haddad
A low-cost and reliable cooling/heating-assisted microextraction (CHaME) instrument was designed and fabricated for use in different modes of microextraction methods. The CHaME setup is able to cool down the sorbent and simultaneously heat the sample in a wide temperature range. Consequently, it can create a large thermal gap between the sorbent and the sample matrix, to promote the release of analytes from the sample tissue and enhance their effective trapping on the microextraction phase. The primary versions of the instrument have previously been evaluated, coupled with different modes of solid- and liquid-phase microextraction strategies...
May 14, 2018: Analyst
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