scholarly journals DNAzyme Sensor for the Detection of Ca2+ Using Resistive Pulse Sensing

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5877
Author(s):  
Imogen Heaton ◽  
Mark Platt
Keyword(s):  
Linear Response ◽  
Tertiary Structure ◽  
Pond Water ◽  
Specific Form ◽  
Conformation Change ◽  
Specific Chemical ◽  
Dna Oligonucleotides ◽  
Resistive Pulse ◽  
Recognition Elements ◽  
Translocation Speed

DNAzymes are DNA oligonucleotides that can undergo a specific chemical reaction in the presence of a cofactor. Ribonucleases are a specific form of DNAzymes where a tertiary structure undergoes cleavage at a single ribonuclease site. The cleavage is highly specificity to co-factors, which makes them excellent sensor recognition elements. Monitoring the change in structure upon cleavage has given rise to many sensing strategies; here we present a simple and rapid method of following the reaction using resistive pulse sensors, RPS. To demonstrate this methodology, we present a sensor for Ca2+ ions in solution. A nanoparticle was functionalised with a Ca2+ DNAzyme, and it was possible to follow the cleavage and rearrangement of the DNA as the particles translocate the RPS. The binding of Ca2+ caused a conformation change in the DNAzyme, which was monitored as a change in translocation speed. A 30 min assay produced a linear response for Ca2+ between 1–9 μm, and extending the incubation time to 60 min allowed for a concentration as low as 0.3 μm. We demonstrate that the signal is specific to Ca2+ in the presence of other metal ions, and we can quantify Ca2+ in tap and pond water samples.

scholarly journals DNAzyme Sensor for the Detection of Metal Ions Using Resistive Pulse Sensing

2020 ◽  
Author(s):  
Imogen Heaton ◽  
Mark Platt
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Pond Water ◽  
Biological Processes ◽  
Resistive Pulse ◽  
Wide Range ◽  
Resistive Pulse Sensing ◽  
Nanopore Sensors ◽  
Translocation Speed ◽  
Specific Metal

<b>DNAzymes are DNA based catalysts that can undergo cleavage upon binding of the target analyte. The cleavage reaction is highly specific, and DNAzymes exists for a wide range of metal ions. The change of structure upon binding of a specific metal ion has given rise to many sensing strategies, but few exist with nanopore sensors. Resistive Pulse Sensing, RPS, is a platform that has emerged in recent years capable of identifying changes in DNA structure and sequence. Here we develop the use of DNAzymes with RPS technologies for the detection of Ca2+ ions in solution. Ca2+ plays an important role in biological processes, critical for cell signally, protein folding and catalysis. Extreme concentrations of Ca2+ within drinking water have also been linked to problems with corrosion, scaling and the taste of water. Using DNAzyme functionalised nanocarriers and RPS, it was possible follow the Ca2+ ions binding to the DNAzyme. The binding of Ca2+ caused a conformation change in the DNAzyme which was monitored as a change in translocation speed. By following the changes to the translocation speed, it is hypothesised that RPS can verify the changes in structure. In addition, the assay allowed the quantification of Ca2+ between 1 – 9 μM, and due its catalytic nature, increasing incubation time from 30 to 90 minutes allowed lower detection limits, down to 0.3 μM. We demonstrate that the speed changes are specific to Ca2+ in the presence of other metal ions, and we can quantify Ca2+ in tap and pond water samples.</b><br>

scholarly journals DNAzyme Sensor for the Detection of Metal Ions Using Resistive Pulse Sensing

2020 ◽  
Author(s):  
Imogen Heaton ◽  
Mark Platt
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Pond Water ◽  
Biological Processes ◽  
Resistive Pulse ◽  
Wide Range ◽  
Resistive Pulse Sensing ◽  
Nanopore Sensors ◽  
Translocation Speed ◽  
Specific Metal

<b>DNAzymes are DNA based catalysts that can undergo cleavage upon binding of the target analyte. The cleavage reaction is highly specific, and DNAzymes exists for a wide range of metal ions. The change of structure upon binding of a specific metal ion has given rise to many sensing strategies, but few exist with nanopore sensors. Resistive Pulse Sensing, RPS, is a platform that has emerged in recent years capable of identifying changes in DNA structure and sequence. Here we develop the use of DNAzymes with RPS technologies for the detection of Ca2+ ions in solution. Ca2+ plays an important role in biological processes, critical for cell signally, protein folding and catalysis. Extreme concentrations of Ca2+ within drinking water have also been linked to problems with corrosion, scaling and the taste of water. Using DNAzyme functionalised nanocarriers and RPS, it was possible follow the Ca2+ ions binding to the DNAzyme. The binding of Ca2+ caused a conformation change in the DNAzyme which was monitored as a change in translocation speed. By following the changes to the translocation speed, it is hypothesised that RPS can verify the changes in structure. In addition, the assay allowed the quantification of Ca2+ between 1 – 9 μM, and due its catalytic nature, increasing incubation time from 30 to 90 minutes allowed lower detection limits, down to 0.3 μM. We demonstrate that the speed changes are specific to Ca2+ in the presence of other metal ions, and we can quantify Ca2+ in tap and pond water samples.</b><br>

Photographic Equidensitometry of High Voltage Electron Images of Thick Noncrystalline Materials

1972 ◽  
Vol 30 ◽  
pp. 594-595
Author(s):  
Keinosuke Kobayashi
Keyword(s):  
High Voltage ◽  
Linear Response ◽  
Thickness Distribution ◽  
Contour Map ◽  
Mass Thickness ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Homogeneous Particle ◽  
Photographic Emulsions ◽  
Logarithmic Relation

Equidensitometry as developed by E. Lau and W. Krug has been little used in the analysis of ordinary electron photomicrographs, yet its application to the high voltage electron images proves merits of this procedure. Proper sets (families) of equidensities as shown in the next page are able to reveal the contour map of mass thickness distribution in thick noncrystalline specimens. The change in density of the electron micrograph is directly related to the mass thickness of corresponding area in the specimen, because of the linear response of photographic emulsions to electrons and the logarithmic relation between electron opacity and mass thickness of amorphous object.This linearity is verified by equidensitometry of a spherical solid object as shown in Fig. 1a. The object is a large (1 μ) homogeneous particle of polystyrene. Fig. 1b is a composite print of three equidensities of the 1st order prepared from Fig. 1a.

Torus Circumference and Thickness Parameters From a Linear DNA Size Series Suggest How Toruses Self-Assemble

1985 ◽  
Vol 43 ◽  
pp. 522-523
Author(s):  
George C. Ruben ◽  
Kenneth A. Marx
Keyword(s):  
Tertiary Structure ◽  
Dna Complexes ◽  
Tertiary Structures ◽  
Self Assembling ◽  
Double Stranded Dna ◽  
Calf Thymus ◽  
Dna Organization ◽  
Condensed Dna ◽  
Dna Size

Certain double stranded DNA bacteriophage and viruses are thought to have their DNA organized into large torus shaped structures. Morphologically, these poorly understood biological DNA tertiary structures resemble spermidine-condensed DNA complexes formed in vitro in the total absence of other macromolecules normally synthesized by the pathogens for the purpose of their own DNA packaging. Therefore, we have studied the tertiary structure of these self-assembling torus shaped spermidine- DNA complexes in a series of reports. Using freeze-etch, low Pt-C metal (10-15Å) replicas, we have visualized the microscopic DNA organization of both calf Thymus( CT) and linear 0X-174 RFII DNA toruses. In these structures DNA is circumferentially wound, continuously, around the torus into a semi-crystalline, hexagonal packed array of parallel DNA helix sections.

Investigation of Some Water Quality Parameters of Pond Water under Mymensingh Municipality

2015 ◽  
Vol 8 (1) ◽  
pp. 85-89
Author(s):  
F Zannat ◽  
MA Ali ◽  
MA Sattar
Keyword(s):  
Water Quality ◽  
Water Samples ◽  
Chemical Properties ◽  
Pond Water ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Urban Region ◽  
Mn Toxicity ◽  
Ph Values ◽  
Drinking Water Standard

A study was conducted to evaluate the water quality parameters of pond water at Mymensingh Urban region. The water samples were collected from 30 ponds located at Mymensingh Urban Region during August to October 2010. The chemical analyses of water samples included pH, EC, Na, K, Ca, S, Mn and As were done by standard methods. The chemical properties in pond water were found pH 6.68 to 7.14, EC 227 to 700 ?Scm-1, Na 15.57 to 36.00 ppm, K 3.83 to 16.16 ppm, Ca 2.01 to 7.29 ppm, S 1.61 to 4.67 ppm, Mn 0.33 to 0.684 ppm and As 0.0011 to 0.0059 ppm. The pH values of water samples revealed that water samples were acidic to slightly alkaline in nature. The EC value revealed that water samples were medium salinity except one sample and also good for irrigation. According to drinking water standard Mn toxicity was detected in pond water. Considering Na, Ca and S ions pond water was safe for irrigation and aquaculture. In case of K ion, all the samples were suitable for irrigation but unsuitable for aquaculture.J. Environ. Sci. & Natural Resources, 8(1): 85-89 2015

Flow velocity and light level drive non-linear response of seagrass Zostera noltei to ammonium enrichment

2016 ◽  
Vol 545 ◽  
pp. 109-121 ◽  
Author(s):  
B Villazán ◽  
FG Brun ◽  
V González‑Ortiz ◽  
F Moreno‑Marín ◽  
TJ Bouma ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Linear Response ◽  
Light Level ◽  
Zostera Noltei ◽  
Non Linear

Critique virale et genre trafiqué dans Valérie par Valérie par La Rédaction

2020 ◽  
Vol 59 (1) ◽  
pp. 51-66
Author(s):  
Gabriel Proulx
Keyword(s):  
Specific Form ◽  
Economic Mechanism ◽  
Ethical Implications ◽  
Literary Forms ◽  
Dominant Ideologies ◽  
Critical Paths ◽  
Political Economic

Valérie par Valérie opens new critical paths which are fertile, though difficult to unpack. Published under the enigmatic and collective name La Rédaction, this book – whose main (or only) author seems to be Christophe Hanna – develops what we could call a viral critique, which seeks to occupy dominant ideologies to undermine them from within rather than oppose them with a new ideology. This article aims firstly to define Hanna's viral critique, based on his own theoretical works and Guy Debord's notion of spectacle as a social and economic mechanism. It then analyzes the specific form taken by that critique in Valérie par Valérie, where the author opposes the separation of literary and non-literary forms, as well as contemporary ultracapitalism and its political-economic ramifications. Finally, the ethical implications of this type of implicit critical exercise are explored through semioethics, in order to determine the efficiency of Hanna's project.

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