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https://www.readbyqxmd.com/read/28929744/optimizing-stem-length-to-improve-ligand-selectivity-in-a-structure-switching-cocaine-binding-aptamer
#1
Miguel A D Neves, Aron A Shoara, Oren Reinstein, Okty Abbasi Borhani, Taylor R Martin, Philip E Johnson
Understanding how aptamer structure and function are related is crucial in the design and development of aptamer-based biosensors. We have analysed a series of cocaine-binding aptamers with different lengths of their stem 1 in order to understand the role that this stem plays in the ligand-induced structure-switching binding mechanism utilized in many of the sensor applications of this aptamer. In the cocaine-binding aptamer the length of stem 1 controls whether the structure-switching binding mechanism for this aptamer occurs or not...
September 20, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28929743/the-design-of-a-dual-channel-self-reference-photoelectrochemical-biosensor
#2
Nan Hao, Ying Zhang, Hui Zhong, Zhou Zhou, Rong Hua, Jing Qian, Qian Liu, Henan Li, Kun Wang
Photoelectrochemical (PEC) biosensors are usually based on the single photocurrent change caused by biorecognition events between analytes and probes. However, the photocurrent may be influenced by other factors besides target analytes and bring a false result. To improve the accuracy and reliability of PEC detection, here we proposed the design of a dual channel self-reference PEC biosensors. CdTe and CdTe-graphene oxide (GO) were chosen as the two PEC active material and modified onto two adjacent areas on the ITO electrode...
September 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28929734/label-free-and-high-throughput-detection-of-biomolecular-interactions-using-a-flatbed-scanner-biosensor
#3
Ugur Aygun, Oguzhan Avci, Elif Seymour, Hakan Urey, M Selim Ünlu, Ayca Yalcin Ozkumur
Fluorescence based microarray detection systems provide sensitive measurements, however variation of probe immobilization and poor repeatability negatively affect the final readout, and thus quantification capability of these systems. Here, we demonstrate a label-free and high-throughput optical biosensor that can be utilized for calibration of fluorescence microarrays. The sensor employs a commercial flatbed scanner, and we demonstrate transformation of this low cost (100 USD) system into an Interferometric Reflectance Imaging Sensor through hardware and software modifications...
September 20, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28929579/in-situ-biosensor-for-detection-mirna-in-living-cells-based-on-carbon-nitride-nanosheets-with-catalytic-hairpin-assembly-amplification
#4
Xianjiu Liao, Liqing Li, Jianbin Pan, Tingting Peng, Bin Ge, Qianli Tang
In this study, an ultrasensitive fluorescence turn-on assay for in situ sensing of intracellular microRNA (miRNA) was developed utilizing a carbon nitride nanosheet (CNNS) and a catalytic hairpin assembly (CHA). The CHA showed favourable signal amplification for low-level biomarkers, and CNNS was an excellent candidate as a fluorescence quencher and gene vector. Moreover, the hairpin DNA of CHA could be adsorbed onto the surface of CNNS. An enzyme-free fluorescence biosensor for ultrasensitive sensing of intracellular miRNA in cells based on CHA and CNNS was designed...
September 19, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/28928405/nanopore-extended-field-effect-transistor-for-selective-single-molecule-biosensing
#5
Ren Ren, Yanjun Zhang, Binoy Paulose Nadappuram, Bernice Akpinar, David Klenerman, Aleksandar P Ivanov, Joshua B Edel, Yuri Korchev
There has been a significant drive to deliver nanotechnological solutions to biosensing, yet there remains an unmet need in the development of biosensors that are affordable, integrated, fast, capable of multiplexed detection, and offer high selectivity for trace analyte detection in biological fluids. Herein, some of these challenges are addressed by designing a new class of nanoscale sensors dubbed nanopore extended field-effect transistor (nexFET) that combine the advantages of nanopore single-molecule sensing, field-effect transistors, and recognition chemistry...
September 19, 2017: Nature Communications
https://www.readbyqxmd.com/read/28928402/core-shell-heterostructured-multiwalled-carbon-nanotubes-reduced-graphene-oxide-nanoribbons-chitosan-a-robust-nanobiocomposite-for-enzymatic-biosensing-of-hydrogen-peroxide-and-nitrite
#6
Veerappan Mani, Mani Govindasamy, Shen-Ming Chen, Tse-Wei Chen, Annamalai Senthil Kumar, Sheng-Tung Huang
A robust nanobiocomposite based on core-shell heterostructured multiwalled carbon nanotubes@reduced graphene oxide nanoribbons (MWCNTs@rGONRs)/chitosan (CHIT) was described for the fabrication of sensitive, selective, reproducible and durable biosensor for hydrogen peroxide (H2O2) and nitrite (NO2(-)). The excellent physicochemical properties of MWCNTs@rGONRs such as, presence of abundant oxygen functionalities, higher area-normalized edge-plane structures and chemically active sites in combination with excellent biocompatibility of CHIT resulting in the versatile immobilization matrix for myoglobin (Mb)...
September 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28927538/advances-in-ligase-chain-reaction-and-ligation-based-amplifications-for-genotyping-assays-detection-and-applications
#7
REVIEW
Abdullah A Gibriel, Ola Adel
Genetic variants have been reported to cause several genetic diseases. Various genotyping assays have been developed for diagnostic and screening purposes but with certain limitations in sensitivity, specificity, cost effectiveness and/or time savings. Since the discovery of ligase chain reaction (LCR) in the late nineties, it became one of the most favored platforms for detecting these variants and also for genotyping low abundant contaminants. Recent and powerful modifications with the integration of various detection strategies such as electrochemical and magnetic biosensors, nanoparticles (NPs), quantum dots, quartz crystal and leaky surface acoustic surface biosensors, DNAzyme, rolling circle amplification (RCA), strand displacement amplification (SDA), surface enhanced raman scattering (SERS), chemiluminescence and fluorescence resonance energy transfer have been introduced to both LCR and ligation based amplifications to enable high-throughput and inexpensive multiplex genotyping with improved robustness, simplicity, sensitivity and specificity...
July 2017: Mutation Research
https://www.readbyqxmd.com/read/28927005/mediatorless-impedance-studies-with-titanium-dioxide-conjugated-gold-nanoparticles-for-hydrogen-peroxide-detection
#8
Nur Hamidah Abdul Halim, Yook Heng Lee, Radha Swathe Priya Malon Marugan, Uda Hashim
An impedimetric-based biosensor constructed using gold nanoparticles (AuNP) entrapped within titanium dioxide (TiO₂) particles for hydrogen peroxide (H₂O₂) detection is the main feature of this research. The matrix of the biosensor employed the surface of TiO₂, which was previously modified with an amine terminal group using 3-Aminopropyltriethoxysilane (APTS) at a low temperature to create a ready to immobilise surface for the biosensor application. Hemoglobin (Hb), which exhibits peroxidase-like activity, was used as the bioreceptor in the biosensor to detect H₂O₂ in solution...
September 18, 2017: Biosensors
https://www.readbyqxmd.com/read/28926823/preparation-characterization-and-application-of-urease-nanoparticles-for-construction-of-an-improved-potentiometric-urea-biosensor
#9
Seema Jakhar, C S Pundir
The nanoparticles (NPs) aggregates of commercial urease from jack beans (Canavalia ensiformis) were prepared by desolvation and glutaraldehyde crosslinking and functionalized by cysteamine dihydrochloride. These enzyme nanoparticles (ENPs) were characterized by transmission electron microscopy (TEM), UV and Fourier transform infrared (FTIR) spectroscopy. The TEM images of urease NPs showed their size in the range, 18-100nm with an average of 51.2nm. The ENPs were more active and stable with a longer shelf life than native enzyme molecules...
September 6, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28925982/osmolyte-like-stabilizing-effects-of-low-gdnhcl-concentrations-on-d-glucose-d-galactose-binding-protein
#10
Alexander V Fonin, Alexandra D Golikova, Irina A Zvereva, Sabato D'Auria, Maria Staiano, Vladimir N Uversky, Irina M Kuznetsova, Konstantin K Turoverov
The ability of d-glucose/d-galactose-binding protein (GGBP) to reversibly interact with its ligands, glucose and galactose, makes this protein an attractive candidate for sensing elements of glucose biosensors. This potential is largely responsible for attracting researchers to study the conformational properties of this protein. Previously, we showed that an increase in the fluorescence intensity of the fluorescent dye 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN) is linked to the holo-form of the GGBP/H152C mutant in solutions containing sub-denaturing concentrations of guanidine hydrochloride (GdnHCl)...
September 19, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28925937/repetitive-immunosensor-with-a-fiber-optic-device-and-antibody-coated-magnetic-beads-for-semi-continuous-monitoring-of-escherichia-coli-o157-h7
#11
Midori Taniguchi, Hirokazu Saito, Kohji Mitsubayashi
A rapid and reproducible fiber-optic immunosensor for Escherichia coli O157:H7 (E. coli O157:H7) was described. The biosensor consisted of a flow cell, an optical fiber with a thin Ni layer, and a PC linked fluorometer. First, the samples with E. coli O157:H7 were incubated with magnetic beads coated with anti-E. coli O157:H7 antibodies and anti-E. coli O157:H7 antibodies labeled cyanine 5 (Cy5) to make sandwich complexes. Then the Cy5-(E. coli O157:H7)-beads were injected into a flow cell and pulled to the magnetized Ni layer on the optical fiber set in the flow cell...
September 19, 2017: Sensors
https://www.readbyqxmd.com/read/28925867/lignocellulosic-biomass-derived-functional-materials-synthesis-and-applications-in-biomedical-engineering
#12
Lei Zhang, Xinwen Peng, Linxin Zhong, Weitian Chua, Zhihua Xiang, Runcang Sun
The pertinent issue of resources shortage arising from global climate change in the recent years has accentuated the importance of materials that are environmental friendly. Despite the merits of current material like cellulose as the most abundant natural polysaccharide on earth, the incorporation of lignocellulosic biomass has the potential to value-add the recent development of cellulose-derivatives in drug delivery systems. Lignocellulosic biomass, with a hierarchical structure, comprised of cellulose, hemicellulose and lignin...
September 18, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28924656/live-cell-sted-imaging-with-the-hyper2-biosensor
#13
Natalia M Mishina, Vsevolod V Belousov
Stimulated emission depletion (STED) microscopy is a popular super resolution imaging technique. Not only synthetic dyes and fluorescent proteins can be utilized as STED fluorophores, but also genetically encoded biosensors. Fusing the biosensor with proteins of interest allows subdiffraction imaging of intracellular macromolecular architecture with simultaneous extraction of functional information about cellular activities. Here, we describe a protocol for live-cell STED microscopy of the HyPer2 biosensor fused to cytoskeletal filaments...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28924139/srphi-ratiometric-ph-biosensors-for-super-resolution-microscopy
#14
Douglas S Richardson, Carola Gregor, Franziska R Winter, Nicolai T Urban, Steffen J Sahl, Katrin I Willig, Stefan W Hell
Fluorescence-based biosensors have become essential tools for modern biology, allowing real-time monitoring of biological processes within living cells. Intracellular fluorescent pH probes comprise one of the most widely used families of biosensors in microscopy. One key application of pH probes has been to monitor the acidification of vesicles during endocytosis, an essential function that aids in cargo sorting and degradation. Prior to the development of super-resolution fluorescence microscopy (nanoscopy), investigation of endosomal dynamics in live cells remained difficult as these structures lie at or below the ~250 nm diffraction limit of light microscopy...
September 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28922492/highly-sensitive-detection-of-protein-biomarkers-with-organic-electrochemical-transistors
#15
Ying Fu, Naixiang Wang, Anneng Yang, Helen Ka-Wai Law, Li Li, Feng Yan
The analysis of protein biomarkers is of great importance in the diagnosis of diseases. Although many convenient and low-cost electrochemical approaches have been extensively investigated, they are not sensitive enough in the detection of protein biomarkers with low concentrations in physiological environments. Here, this study reports a novel organic-electrochemical-transistor-based biosensor that can successfully detect cancer protein biomarkers with ultrahigh sensitivity. The devices are operated by detecting electrochemical activity on gate electrodes, which is dependent on the concentrations of proteins labeled with catalytic nanoprobes...
September 18, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28922391/impedance-biosensor-for-real-time-monitoring-and-prediction-of-thrombotic-individual-profile-in-flowing-blood
#16
Denise De Zanet, Monica Battiston, Elisabetta Lombardi, Ruben Specogna, Francesco Trevisan, Luigi De Marco, Antonio Affanni, Mario Mazzucato
A new biosensor for the real-time analysis of thrombus formation is reported. The fast and accurate monitoring of the individual thrombotic risk represents a challenge in cardiovascular diagnostics and in treatment of hemostatic diseases. Thrombus volume, as representative index of the related thrombotic status, is usually estimated with confocal microscope at the end of each in vitro experiment, without providing a useful behavioral information of the biological sample such as platelets adhesion and aggregation in flowing blood...
2017: PloS One
https://www.readbyqxmd.com/read/28922354/reconstructing-promoter-activity-from-lux-bioluminescent-reporters
#17
Mudassar Iqbal, Neil Doherty, Anna M L Page, Saara N A Qazi, Ishan Ajmera, Peter A Lund, Theodore Kypraios, David J Scott, Philip J Hill, Dov J Stekel
The bacterial Lux system is used as a gene expression reporter. It is fast, sensitive and non-destructive, enabling high frequency measurements. Originally developed for bacterial cells, it has also been adapted for eukaryotic cells, and can be used for whole cell biosensors, or in real time with live animals without the need for euthanasia. However, correct interpretation of bioluminescent data is limited: the bioluminescence is different from gene expression because of nonlinear molecular and enzyme dynamics of the Lux system...
September 18, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28921510/development-of-a-formaldehyde-biosensor-with-application-to-synthetic-methylotrophy
#18
Benjamin M Woolston, Timothy Roth, Ishwar Kohale, David Liu, Gregory Stephanopoulos
Formaldehyde is a prevalent environmental toxin and a key intermediate in single carbon metabolism. The ability to monitor formaldehyde concentration is therefore of interest for both environmental monitoring and for metabolic engineering of native and synthetic methylotrophs, but current methods suffer from low sensitivity, complex workflows, or require expensive analytical equipment. Here we develop a formaldehyde biosensor based on the FrmR repressor protein and cognate promoter of E. coli. Optimization of the native repressor binding site and regulatory architecture enabled detection at levels as low as 1 µM...
September 16, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28920599/magnetic-nanoparticle-enhanced-surface-plasmon-resonance-biosensor-for-extracellular-vesicle-analysis
#19
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
https://www.readbyqxmd.com/read/28918898/endoplasmic-reticulum-transport-of-glutathione-by-sec61-is-regulated-by-ero1-and-bip
#20
Alise J Ponsero, Aeid Igbaria, Maxwell A Darch, Samia Miled, Caryn E Outten, Jakob R Winther, Gael Palais, Benoit D'Autréaux, Agnès Delaunay-Moisan, Michel B Toledano
In the endoplasmic reticulum (ER), Ero1 catalyzes disulfide bond formation and promotes glutathione (GSH) oxidation to GSSG. Since GSSG cannot be reduced in the ER, maintenance of the ER glutathione redox state and levels likely depends on ER glutathione import and GSSG export. We used quantitative GSH and GSSG biosensors to monitor glutathione import into the ER of yeast cells. We found that glutathione enters the ER by facilitated diffusion through the Sec61 protein-conducting channel, while oxidized Bip (Kar2) inhibits transport...
September 11, 2017: Molecular Cell
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