scholarly journals Optical Graphene-Based Biosensor for Nucleic Acid Detection; Influence of Graphene Functionalization and Ionic Strength

2018 ◽  
Vol 19 (10) ◽  
pp. 3230 ◽  
Author(s):  
Diana Becheru ◽  
George Vlăsceanu ◽  
Adela Banciu ◽  
Eugeniu Vasile ◽  
Mariana Ioniţă ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Ionic Strength ◽  
Nucleic Acid ◽  
Molecular Interaction ◽  
Rational Design ◽  
Nucleic Acid Detection ◽  
Fluorescence Signal ◽  
Main Challenge ◽  
Graphene Functionalization

A main challenge for optical graphene-based biosensors detecting nucleic acid is the selection of key parameters e.g. graphenic chemical structure, nanomaterial dispersion, ionic strength, and appropriate molecular interaction mechanisms. Herein we study interactions between a fluorescein-labelled DNA (FAM-DNA) probe and target single-stranded complementary DNA (cDNA) on three graphenic species, aiming to determine the most suitable platform for nucleic acid detection. Graphene oxide (GO), carboxyl graphene (GO-COOH) and reduced graphene oxide functionalized with PEGylated amino groups (rGO-PEG-NH2, PEG (polyethylene glycol)) were dispersed and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The influence of ionic strength on molecular interaction with DNA was examined by fluorescence resonance energy transfer (FRET) comparing fluorescence intensity and anisotropy. Results indicated an effect of graphene functionalization, dispersion and concentration-dependent quenching, with GO and GO-COOH having the highest quenching abilities for FAM-DNA. Furthermore, GO and GO-COOH quenching was accentuated by the addition of either MgCl2 or MgSO4 cations. At 10 mM MgCl2 or MgSO4, the cDNA induced a decrease in fluorescence signal that was 2.7-fold for GO, 3.4-fold for GO-COOH and 4.1-fold for rGO-PEG-NH2. Best results, allowing accurate target detection, were observed when selecting rGO-PEG-NH2, MgCl2 and fluorescence anisotropy as an advantageous combination suitable for nucleic acid detection and further rational design biosensor development.

A biosensor for the detection of single base mismatches in microRNA

2015 ◽  
Vol 51 (78) ◽  
pp. 14597-14600 ◽  
Author(s):  
Jieon Lee ◽  
Ginam Park ◽  
Dal-Hee Min
Keyword(s):  
Graphene Oxide ◽  
Nucleic Acid ◽  
Nucleic Acid Detection ◽  
Single Base ◽  
Target Probe

Graphene oxide enables highly sequence specific nucleic acid detection by selectively removing the signal from a mismatched target/probe duplex.

Graphene Oxide-based Amplified Fluorescence Sensor for Nucleic Acid Detection through Target-catalyzed Hairpin Assembly

2015 ◽  
Vol 44 (10) ◽  
pp. 1353-1355 ◽  
Author(s):  
Yusuke Kitamura ◽  
Takaaki Miyahata ◽  
Hirotaka Matsuura ◽  
Kazuto Hatakeyama ◽  
Takaaki Taniguchi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Nucleic Acid ◽  
Fluorescence Sensor ◽  
Nucleic Acid Detection ◽  
Catalyzed Hairpin Assembly

The ionic strength dependence of chromatin folding

1978 ◽  
Vol 36 (2) ◽  
pp. 220-221
Author(s):  
F. Thoma ◽  
TH. Koller
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ionic Strength ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Carbon Supports ◽  
Ionic Strength Dependence ◽  
Chromatin Folding ◽  
Strength Dependence ◽  
Preparation Techniques

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.

Nucleic Acid Molecules Prepared by Monolayer Techniques

1972 ◽  
Vol 30 ◽  
pp. 178-179
Author(s):  
Dimitrij Lang
Keyword(s):  
Electron Microscopy ◽  
Standard Deviation ◽  
Nucleic Acid ◽  
Cytochrome C ◽  
Nucleic Acids ◽  
Contour Length ◽  
Sample Standard Deviation ◽  
Molecular Weights ◽  
Length Measurements ◽  
Protein Monolayer

The success of the protein monolayer technique for electron microscopy of individual DNA molecules is based on the prevention of aggregation and orientation of the molecules during drying on specimen grids. DNA adsorbs first to a surface-denatured, insoluble cytochrome c monolayer which is then transferred to grids, without major distortion, by touching. Fig. 1 shows three basic procedures which, modified or not, permit the study of various important properties of nucleic acids, either in concert with other methods or exclusively:1) Molecular weights relative to DNA standards as well as number distributions of molecular weights can be obtained from contour length measurements with a sample standard deviation between 1 and 4%.

Molecular insights on the dynamic stability of peptide nucleic acid functionalized carbon and boron nitride nanotubes

2021 ◽  
Vol 23 (1) ◽  
pp. 219-228
Author(s):  
Nabanita Saikia ◽  
Mohamed Taha ◽  
Ravindra Pandey
Keyword(s):  
Nucleic Acid ◽  
Boron Nitride ◽  
Nucleic Acids ◽  
Dynamic Stability ◽  
Peptide Nucleic Acid ◽  
Rational Design ◽  
Peptide Nucleic Acids ◽  
Boron Nitride Nanotubes ◽  
Molecular Hybrids ◽  
Single Wall Nanotubes

The rational design of self-assembled nanobio-molecular hybrids of peptide nucleic acids with single-wall nanotubes rely on understanding how biomolecules recognize and mediate intermolecular interactions with the nanomaterial's surface.

Synthesis and Electrochemical Properties of NiFe-Se/rGO Nanocomposites

2020 ◽  
Vol 13 ◽  
Author(s):  
Rouwei Yan ◽  
Biao Xu ◽  
K. P. Annamalai ◽  
Tianlu Chen ◽  
Zhiming Nie ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Energy Storage ◽  
Synergistic Effects ◽  
Nitrogen Adsorption ◽  
Storage Device ◽  
Energy Storage And Conversion ◽  
Step Method ◽  
Practical Applications ◽  
Device Applications

Background : Renewable energies are in great demand because of the shortage of traditional fossil energy and the associated environmental problems. Ni and Se-based materials are recently studied for energy storage and conversion owing to their reasonable conductivities and enriched redox activities as well as abundance. However, their electrochemical performance is still unsatisfactory for practical applications. Objective: To enhance the capacitance storage of Ni-Se materials via modification of their physiochemical properties with Fe. Methods: A two-step method was carried out to prepare FeNi-Se loaded reduced graphene oxide (FeNi-Se/rGO). In the first step, metal salts and graphene oxide (GO) were mixed under basic condition and autoclaved to obtain hydroxide intermediates. As a second step, selenization process was carried out to acquire FeNi-Se/rGO composites. Results: X-ray diffraction measurements (XRD), nitrogen adsorption at 77K, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were carried out to study the structures, porosities and the morphologies of the composites. Electrochemical measurements revealed that FeNi-Se/rGO notably enhanced capacitance than the NiSe/G composite. This enhanced performance was mainly attributed to the positive synergistic effects of Fe and Ni in the composites, which not only had influence on the conductivity of the composite but also enhanced redox reactions at different current densities. Conclusion: NiFe-Se/rGO nanocomposites were synthesized in a facile way. The samples were characterized physicochemically and electrochemically. NiFeSe/rGO giving much higher capacitance storage than the NiSe/rGO explained that the nanocomposites could be an electrode material for energy storage device applications.

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