Current Advances and Prospects on Implementation of Highly Sensitive Aptamer-based Dual System for Melamine Detection: New Promising Tool of Great Affinity

ABSTRACTNuclear magnetic resonance (NMR) spin lattice relaxation is highly sensitive to the nature, amount, and homogeneity of unpaired-electron-containing impurities in silicon carbide and similar solids, and is a promising tool for the study of dopants and impurities. In nitrogen-doped 6H silicon carbide, 13C and 29Si NMR spin lattice relaxation is highly site-dependent. Not only do carbon sites relax much more rapidly than the corresponding silicon sites, but also there are unprecedented differences in relaxation efficiency among the different carbon (and silicon) sites, consistent with much higher unpaired electron density at the higher-symmetry (Types A and B) sites than at the lowest-symmetry (Type C) site. In contrast, all sites relax at equivalent rates in undoped samples and in commercial abrasive grade material with high levels of impurities, although there are large differences in relaxation efficiency among samples. The change in the nature of the relaxation process, from exponential in high-purity to stretched exponential in lower-purity samples, is apparently related to changes in unpaired-electron mobility.

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A Highly Sensitive Amperometric Glutamate Oxidase Microbiosensor Based on a Reduced Graphene Oxide/Prussian Blue Nanocube/Gold Nanoparticle Composite Film-Modified Pt Electrode

Sensors ◽

10.3390/s20102924 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2924 ◽

Cited By ~ 2

Author(s):

Jing Chen ◽

Qiwen Yu ◽

Wei Fu ◽

Xing Chen ◽

Quan Zhang ◽

...

Keyword(s):

Graphene Oxide ◽

Prussian Blue ◽

Reduced Graphene Oxide ◽

High Sensitivity ◽

Small Dimension ◽

Simple Method ◽

Promising Tool ◽

Glutamate Oxidase ◽

Reduced Graphene ◽

Highly Sensitive

A simple method that relies only on an electrochemical workstation has been investigated to fabricate a highly sensitive glutamate microbiosensor for potential neuroscience applications. In this study, in order to develop the highly sensitive glutamate electrode, a 100 µm platinum wire was modified by the electrochemical deposition of gold nanoparticles, Prussian blue nanocubes, and reduced graphene oxide sheets, which increased the electroactive surface area; and the chitosan layer, which provided a suitable environment to bond the glutamate oxidase. The optimization of the fabrication procedure and analytical conditions is described. The modified electrode was characterized using field emission scanning electron microscopy, impedance spectroscopy, and cyclic voltammetry. The results exhibited its excellent sensitivity for glutamate detection (LOD = 41.33 nM), adequate linearity (50 nM–40 µM), ascendant reproducibility (RSD = 4.44%), and prolonged stability (more than 30 repetitive potential sweeps, two-week lifespan). Because of the important role of glutamate in neurotransmission and brain function, this small-dimension, high-sensitivity glutamate electrode is a promising tool in neuroscience research.

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A Highly Sensitive and Selective Probe for the Colorimetric Detection of Mn(II) Based on the Antioxidative Selenium and Nitrogen Co-Doped Carbon Quantum Dots and ABTS•+

Frontiers in Chemistry ◽

10.3389/fchem.2021.658105 ◽

2021 ◽

Vol 9 ◽

Author(s):

Qinhai Xu ◽

Xiaolin Liu ◽

Yanglin Jiang ◽

Peng Wang

Keyword(s):

Quantum Dots ◽

Citric Acid ◽

Detection Limit ◽

Sodium Selenite ◽

Tap Water ◽

Colorimetric Detection ◽

Carbon Quantum Dots ◽

Promising Tool ◽

Highly Sensitive ◽

Co Doped

Herein, selenium and nitrogen co-doped carbon quantum dots (Se/N-CQDs) were hydrothermally synthesized by using citric acid, histidine, and sodium selenite, which had sp3 and sp2 hybridized carbon atoms and showed excitation-dependent fluorescence behavior. Furthermore, due to the redox reaction of ABTS•+ and Se/N-CQDs, Se/N-CQDs had the excellent antioxidant capacity that it was demonstrated by scavenging ABTS•+ with the fading of blue. Based on the synergistic effect of Se/N-CQDs and Mn(II) on ABTS•+, Se/N-CQDs and ABTS•+, as a stable, sensitive, selective, and reproducible colorimetric sensor, was applied to the detection of Mn(II) with a detection limit of 1.69 μM and a linear range of 0 to 142.90 μM. More importantly, the probe was successfully applied to detecting Mn(II) in tap water, illustrating that it could be a promising tool for Mn(II) detection in water environments.

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Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites

Biosensors ◽

10.3390/bios11040114 ◽

2021 ◽

Vol 11 (4) ◽

pp. 114

Author(s):

Yunjeong Park ◽

Min-Sung Hong ◽

Woo-Hyuk Lee ◽

Jung-Gu Kim ◽

Kyunghoon Kim

Keyword(s):

Tumor Marker ◽

Limit Of Detection ◽

Biological Fluid ◽

Low Cost ◽

High Sensitivity ◽

Label Free ◽

Electrochemical Aptasensor ◽

Promising Tool ◽

Highly Sensitive ◽

Endothelial Growth Factor

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

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Classification and Identification of Three Vintage Designated Hungarian Spirits by Their Volatile Compounds

Periodica Polytechnica Chemical Engineering ◽

10.3311/ppch.11078 ◽

2017 ◽

Vol 62 (2) ◽

pp. 175

Author(s):

Attila G. Kovács ◽

Attila Szöllősi ◽

Dániel Szöllősi ◽

Ilona A. Panyik ◽

László Nagygyörgy ◽

...

Keyword(s):

Alcoholic Beverage ◽

Sour Cherry ◽

Chemometric Method ◽

Ethyl Propionate ◽

Classification Rate ◽

Linear Discriminant ◽

Promising Tool ◽

Highly Sensitive

The quality of fruit based spirits varies year to year; therefore, the identification of the vintage of a distilled alcoholic beverage is necessary, but requires highly sensitive analytics. The interpretation of the gathered data requires a well-adapted chemometric method. In this study, Hungarian apple, sour cherry and plum distillates (pálinka’s) from different vintages were analyzed, classified and identified using volatile composition analyzed by GC-MS. The fruit’s origin, fermentation technique and distillation were the same at all the fruits; the only differences in the samples were their vintages (2010, 2011 and 2012). Analysis of variance (ANOVA) and Linear discriminant analysis (LDA) was applied for classification and components’ identification related to the vintage effect. The samples were successfully classified (correct classification rate ranging from 75 to 100%), three components are found to be related to the vintage effect regardless the fruit type: propanol, butanol and ethyl-propionate. GC-MS data proved to be a promising tool for classification of fruit distillate vintages.

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Electrochemically Pretreated Carbon Microfiber Electrodes as Sensitive HPLC-EC Detectors

The Scientific World JOURNAL ◽

10.1100/2012/295802 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Zdenka Bartosova ◽

Daniel Riman ◽

Petr Jakubec ◽

Vladimir Halouzka ◽

Jan Hrbac ◽

...

Keyword(s):

Liquid Chromatography ◽

Carbon Fibers ◽

High Performance ◽

Amperometric Detection ◽

Promising Tool ◽

Highly Sensitive ◽

Model Set ◽

Carbon Microfiber ◽

Carbon Fiber Microelectrodes ◽

Treated Carbon

The paper focuses on the analysis and detection of electroactive compounds using high-performance liquid chromatography (HPLC) combined with electrochemical detection (EC). The fabrication and utilization of electrochemically treated carbon fiber microelectrodes (CFMs) as highly sensitive amperometric detectors in HPLC are described. The applied pretreatment procedure is beneficial for analytical characteristics of the sensor as demonstrated by analysis of the model set of phenolic acids. The combination of CFM with separation power of HPLC technique allows for improved detection limits due to unique electrochemical properties of carbon fibers. The CFM proved to be a promising tool for amperometric detection in liquid chromatography.

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Ovarian Dysfunction in Fetally Irradiated Beagles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080717 ◽

1977 ◽

Vol 35 ◽

pp. 658-659

Author(s):

T. M. Seed ◽

M. H. Sanderson ◽

D. L. Gutzeit ◽

T. E. Fritz ◽

D. V. Tolle ◽

...

Keyword(s):

Gamma Rays ◽

Low Dose ◽

Long Term Effects ◽

Ovarian Dysfunction ◽

Dose Rates ◽

Highly Sensitive ◽

Microscopic Evaluation ◽

Ovarian Pathology ◽

Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

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Fluorescence ratio imaging of dynamic intracellular ionic signals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102298 ◽

1988 ◽

Vol 46 ◽

pp. 42-43

Author(s):

R. Y. Tsien ◽

A. Minta ◽

M. Poenie ◽

J.P.Y. Kao ◽

A. Harootunian

Keyword(s):

Binding Sites ◽

Living Cells ◽

Molecular Engineering ◽

Ph Indicators ◽

Highly Sensitive ◽

Fluorescence Ratio Imaging ◽

Ratio Imaging ◽

Technical Advances ◽

Indicator Dyes ◽

Fluorescein Dyes

Recent technical advances now enable the continuous imaging of important ionic signals inside individual living cells with micron spatial resolution and subsecond time resolution. This methodology relies on the molecular engineering of indicator dyes whose fluorescence is strong and highly sensitive to ions such as Ca2+, H+, or Na+, or Mg2+. The Ca2+ indicators, exemplified by fura-2 and indo-1, derive their high affinity (Kd near 200 nM) and selectivity for Ca2+ to a versatile tetracarboxylate binding site3 modeled on and isosteric with the well known chelator EGTA. The most commonly used pH indicators are fluorescein dyes (such as BCECF) modified to adjust their pKa's and improve their retention inside cells. Na+ indicators are crown ethers with cavity sizes chosen to select Na+ over K+: Mg2+ indicators use tricarboxylate binding sites truncated from those of the Ca2+ chelators, resulting in a more compact arrangement of carboxylates to suit the smaller ion.

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Various technic for the measurement of step thickness on crystal surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109331 ◽

1978 ◽

Vol 36 (1) ◽

pp. 438-439

Author(s):

C. Boulesteix ◽

C. Colliex ◽

C. Mory ◽

B. Pardo ◽

D. Renard

Keyword(s):

Critical Thickness ◽

Symmetric Case ◽

Transmitted Intensity ◽

Crystal Surfaces ◽

Bright Field ◽

Excited Wave ◽

Highly Sensitive ◽

Contrast Mechanisms ◽

Step Thickness ◽

Thickness Variations

Contrast mechanisms, which are responsible of the various types of image formation, are generally thickness dependant. In the following, two imaging modes in the 100 kV CTEM are described : they are highly sensitive to thickness variations and can be used for quantitative estimations of step heights.Detailed calculations (1) of the bright-field intensity have been carried out in the 3 (or 2N+l)-beam symmetric case. They show that in given conditions, the two important symmetric Bloch waves interfere most strongly at a critical thickness for which they have equal emergent amplitudes (the more excited wave at the entrance surface is also the more absorbed). The transmitted intensity I for a Nd2O3 specimen has been calculated as a function of thickness t. The capacity of the method to detect a step and measure its height can be more clearly deduced from a plot of dl/Idt as shown in fig. 1.

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Estimation of the noise in TEM image recorded on “imaging plate”

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128055 ◽

1987 ◽

Vol 45 ◽

pp. 748-749

Author(s):

T. Oikawa ◽

N. Mori ◽

T. Katoh ◽

Y. Harada ◽

J. Miyahara ◽

...

Keyword(s):

Low Dose ◽

Quantum Noise ◽

Laser Light ◽

Imaging Plate ◽

Total System ◽

Electron Dose ◽

X Ray ◽

Image Recording ◽

Recording Material ◽

Highly Sensitive

The “Imaging Plate”(IP) is a highly sensitive image recording plate for X-ray radiography. It has been ascertained that the IP has superior properties and high practicability as an image recording material in a TEM. The sensitivity, one of the properties, is about 3 orders higher than that of conventional photo film. The IP is expected to be applied to low dose techniques. In this paper, an estimation of the quantum noise on the TEM image which appears in case of low electron dose on the IP is reported.In this experiment, the JEM-2000FX TEM and an IP having the same size as photo film were used.Figure 1 shows the schematic diagram of the total system including the TEM used in this experiment. In the reader, He-Ne laser light is scanned across the IP, then blue light is emitted from the IP.

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