scholarly journals Toxicity of Graphene Shells, Graphene Oxide, and Graphene Oxide Paper Evaluated withEscherichia coliBiotests

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Ludmila V. Efremova ◽  
Alexey S. Vasilchenko ◽  
Eduard G. Rakov ◽  
Dmitry G. Deryabin
Keyword(s):  
Escherichia Coli ◽  
Graphene Oxide ◽  
Aqueous Suspension ◽  
Cell Membrane Permeability ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mechanism Of Toxicity ◽  
Bioluminescence Inhibition ◽  
Graphene Oxide Paper ◽  
Microscopy Data

The plate-like graphene shells (GS) produced by an original methane pyrolysis method and their derivatives graphene oxide (GO) and graphene oxide paper (GO-P) were evaluated with luminescentEscherichia colibiotests and additional bacterial-based assays which together revealed the graphene-family nanomaterials’ toxicity and bioactivity mechanisms. Bioluminescence inhibition assay, fluorescent two-component staining to evaluate cell membrane permeability, and atomic force microscopy data showed GO expressed bioactivity in aqueous suspension, whereas GS suspensions and the GO-P surface were assessed as nontoxic materials. The mechanism of toxicity of GO was shown not to be associated with oxidative stress in the targetedsoxS::luxandkatG::luxreporter cells; also, GO did not lead to significant mechanical disruption of treated bacteria with the release of intracellular DNA contents into the environment. The well-coordinated time- and dose-dependent surface charge neutralization and transport and energetic disorders in theEscherichia colicells suggest direct membrane interaction, internalization, and perturbation (i.e., “membrane stress”) as a clue to graphene oxide’s mechanism of toxicity.

Combined AFM-SEM testing for mechanical property determination of graphene oxide paper

2012 ◽  
Vol 1407 ◽  
Author(s):  
Congwei Wang ◽  
Asa H. Barber
Keyword(s):  
Graphene Oxide ◽  
Ion Beam ◽  
Force Microscopy ◽  
Atomic Force ◽  
Focussed Ion Beam ◽  
Graphene Oxide Paper ◽  
Sample Width ◽  
Testing Condition ◽  
Vacuum Testing

ABSTRACTA novel technique combining both atomic force microscopy (AFM) and scanning electron microscopy (SEM) is used to test the mechanical properties of densely-packed graphene oxide (GO) paper. Individual beams of GO paper with variable widths were prepared using focussed ion beam (FIB) microscopy and tensile tested to failure using the AFM while observing with SEM. A variation in the tensile strength of the GO paper beams up to 64.8 MPa was recorded in the vacuum testing condition. An increase in breaking stress of GO paper with decreasing sample width was determined and proposed as being due to fewer defects present in GO beams of smaller width.

scholarly journals Molecular force transfer mechanisms in graphene oxide paper evaluated using atomic force microscopy and in situ synchrotron micro FT-IR spectroscopy

Nanoscale ◽  
2014 ◽  
Vol 6 (23) ◽  
pp. 14404-14411 ◽  
Author(s):  
Congwei Wang ◽  
Mark D. Frogley ◽  
Gianfelice Cinque ◽  
Lu-Qi Liu ◽  
Asa H. Barber
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Force Microscopy ◽  
Atomic Force ◽  
Molecular Force ◽  
Force Transfer ◽  
Ft Ir ◽  
Graphene Oxide Paper ◽  
Ft Ir Spectroscopy

The mechanical properties of graphene oxide (GO) paper are critically defined both by the mechanical properties of the constituent GO sheets and the interaction between these sheets.

scholarly journals Photocatalytic reduction of graphene oxide with cuprous oxide film under UV-vis irradiation

2020 ◽  
Vol 59 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Yao Wang ◽  
Jianqing Feng ◽  
Lihua Jin ◽  
Chengshan Li
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Photocatalytic Reduction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reduced Graphene ◽  
Reduction Efficiency ◽  
Metal Organic ◽  
Reduction Effect

AbstractWe have grown Cu2O films by different routes including self-oxidation and metal-organic deposition (MOD). The reduction efficiency of Cu2O films on graphene oxide (GO) synthesized by modified Hummer’s method has been studied. Surface morphology and chemical state of as-prepared Cu2O film and GO sheets reduced at different conditions have also been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Results show that self-oxidation Cu2O film is more effective on phtocatalytic reduction of GO than MOD-Cu2O film. Moreover, reduction effect of self-oxidation Cu2O film to GO is comparable to that of environmental-friendly reducing agent of vitamin C. The present results offer a potentially eco-friendly and low-cost approach for the manufacture of reduced graphene oxide (RGO) by photocatalytic reduction.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

scholarly journals Dynamic mechanisms of CRISPR interference by Escherichia coli CRISPR-Cas3

2021 ◽  
Author(s):  
Kazuto Yoshimi ◽  
Kohei TAKESHITA ◽  
Noriyuki Kodera ◽  
Satomi Shibumura ◽  
Yuko Yamauchi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Speed ◽  
Dna Helicase ◽  
Type I ◽  
Loop Formation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Target Strand ◽  
Target Dna

Type I CRISPR-Cas3 uses an RNA-guided multi Cas-protein complex, Cascade, which detects and degrades foreign nucleic acids via the helicase-nuclease Cas3 protein. Despite many studies using cryoEM and smFRET, the precise mechanism of Cas3-mediated cleavage and degradation of target DNA remains elusive. Here we reconstitute the CRISPR-Cas3 system in vitro to show how the Escherichia coli Cas3 (EcoCas3) with EcoCascade exhibits collateral non-specific ssDNA cleavage and target specific DNA degradation. Partial binding of EcoCascade to target DNA with tolerated mismatches within the spacer sequence, but not the PAM, elicits collateral ssDNA cleavage activity of recruited EcoCas3. Conversely, stable binding with complete R-loop formation drives EcoCas3 to nick the non-target strand (NTS) in the bound DNA. Helicase-dependent unwinding then combines with trans ssDNA cleavage of the target strand and repetitive cis cleavage of the NTS to degrade the target dsDNA substrate. High-speed atomic force microscopy demonstrates that EcoCas3 bound to EcoCascade repeatedly reels and releases the target DNA, followed by target fragmentation. Together, these results provide a revised model for collateral ssDNA cleavage and target dsDNA degradation by CRISPR-Cas3, furthering understanding of type I CRISPR priming and interference and informing future genome editing tools.

Deconvolution of atomic force microscopy data for cellular and molecular imaging

2006 ◽  
Vol 23 (3) ◽  
pp. 73-83 ◽  
Author(s):  
L. Udpa ◽  
V.M. Ayres ◽  
Yuan Fan ◽  
Qian Chen ◽  
S.A. Kumar
Keyword(s):  
Atomic Force Microscopy ◽  
Molecular Imaging ◽  
Atomic Force Microscopy Data ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Data

scholarly journals Electrodeposition of NiSn-rGO Composite Coatings from Deep Eutectic Solvents and Their Physicochemical Characterization

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1455
Author(s):  
Sabrina Patricia Rosoiu ◽  
Aida Ghiulnare Pantazi ◽  
Aurora Petica ◽  
Anca Cojocaru ◽  
Stefania Costovici ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Choline Chloride ◽  
Physicochemical Characterization ◽  
Metallic Matrix ◽  
Deep Eutectic Solvents ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reduced Graphene

The present work describes, for the first time, the electrodeposition of NiSn alloy/reduced graphene oxide composite coatings (NiSn-rGO) obtained under pulse current electrodeposition conditions from deep eutectic solvents (choline chloride: ethylene glycol eutectic mixtures) containing well-dispersed GO nanosheets. The successful incorporation of the carbon-based material into the metallic matrix has been confirmed by Raman spectroscopy and cross-section scanning electron microscopy (SEM). A decrease in the crystallite size of the coating was evidenced when graphene oxide was added to the electrolyte. Additionally, the topography and the electrical properties of the materials were investigated by atomic force microscopy (AFM). The corrosion behavior in 0.5 M NaCl solution was analyzed through potentiodynamic polarization and electrochemical impedance spectroscopy methods for different immersion periods, up to 336 h, showing a slightly better corrosion performance as compared to pure NiSn alloy.

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