scholarly journals Investigation of the Morphology and Electrical Properties of Graphene Used in the Development of Biosensors for Detection of Influenza Viruses

Biosensors ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 8
Author(s):  
Natalia M. Shmidt ◽  
Alexander S. Usikov ◽  
Evgeniia I. Shabunina ◽  
Alexey V. Nashchekin ◽  
Ekaterina V. Gushchina ◽  
...  
Keyword(s):  
Low Frequency ◽  
Influenza Viruses ◽  
Virus Concentration ◽  
Frequency Noise ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Response Versus ◽  
Phosphate Buffered Saline ◽  
Biosensor Response

In this study, we discuss the mechanisms behind changes in the conductivity, low-frequency noise, and surface morphology of biosensor chips based on graphene films on SiC substrates during the main stages of the creation of biosensors for detecting influenza viruses. The formation of phenylamine groups and a change in graphene nano-arrangement during functionalization causes an increase in defectiveness and conductivity. Functionalization leads to the formation of large hexagonal honeycomb-like defects up to 500 nm, the concentration of which is affected by the number of bilayer or multilayer inclusions in graphene. The chips fabricated allowed us to detect the influenza viruses in a concentration range of 10−16 g/mL to 10−10 g/mL in PBS (phosphate buffered saline). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) revealed that these defects are responsible for the inhomogeneous aggregation of antibodies and influenza viruses over the functionalized graphene surface. Non-uniform aggregation is responsible for a weak non-linear logarithmic dependence of the biosensor response versus the virus concentration in PBS. This feature of graphene nano-arrangement affects the reliability of detection of extremely low virus concentrations at the early stages of disease.

scholarly journals Investigation of electrolysis-related modification of graphene films in biosensors

2021 ◽  
Vol 2103 (1) ◽  
pp. 012103
Author(s):  
I A Eliseyev ◽  
A S Usikov ◽  
S P Lebedev ◽  
A D Roenkov ◽  
M V Puzyk ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Kelvin Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Electrolysis Mode ◽  
Modification Of The Surface

Abstract In this work, the modification of the surface parameters of graphene chips after electrolysis treatment in a NaClO4 aqueous solution has been studied. Two electrolysis modes have been analysed. In the first one, a negative potential (-0.2 V) is applied to the graphene chips, while in the second one the potential is positive (0.8 V). Investigation using a number of techniques including atomic force microscopy, Kelvin probe force microscopy, Raman spectroscopy, measurements of current-voltage characteristics and low-frequency noise has shown that the electrolysis mode with application of a positive potential on graphene chips decreases the 1/f noise and allows one to obtain a uniform surface potential distribution while leaving the graphene structure undamaged. The results of this study help to understand the efficiency and reproducibility of the procedure for electrolysis treatment of graphene chips.

Comparison of Epitaxial Graphene on Si-face and C-face 6H-SiC

2011 ◽  
Vol 1284 ◽  
Author(s):  
Shin Mou ◽  
J. J. Boeckl ◽  
L. Grazulis ◽  
B. Claflin ◽  
Weijie Lu ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Raman Spectroscopy ◽  
High Vacuum ◽  
Hall Effect Measurement ◽  
Radiative Heating ◽  
Furnace Chamber ◽  
Vacuum Furnace ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films

ABSTRACTWe present atomic force microscopy (AFM), Hall-effect measurement, and Raman spectroscopy results from graphene films on 6H-SiC (0001) and (000-1) faces (Si-face and C-face, respectively) produced by radiative heating in a high vacuum furnace chamber through thermal decomposition. We observe that the formation of graphene on the two faces of SiC is different in terms of the surface morphology, graphene thickness, Hall mobility, and Raman spectra. In general, graphene films on the SiC C-face are thicker with higher mobilities than those grown on the Si-face.

Graphene growth on SiC and other substrates using carbon sources

2011 ◽  
Vol 1284 ◽  
Author(s):  
W. C. Mitchel ◽  
J. H. Park ◽  
Howard E. Smith ◽  
L. Grazulis ◽  
S. Mou ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Carbon Flux ◽  
Carbon Sources ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Additional Control ◽  
P Type ◽  
Type Conduction

ABSTRACTDirect deposition of graphene from carbon sources on foreign substrates without the use of metal catalysts is shown to be an effective process with several advantages over other growth techniques. Carbon source molecular beam epitaxy (CMBE) in particular provides an additional control parameter in carbon flux and enables growth on substrates other than SiC, including oxidized Si and sapphire. CMBE using thermally evaporated C60 and a heated graphite filament on SiC is reported here. The graphene films were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and Hall effect. Graphene films on Si-face SiC grown using the C60 source have Bernal-like stacking and n-type conduction while those grown using the graphite filament have turbostratic stacking and p-type conduction. The sheet concentration for both n- and p-type doping is linearly dependent on film thickness.

Fabrication of Uniformly Growing Graphene Films via the Dip-Coating Method

2013 ◽  
Vol 320 ◽  
pp. 185-189
Author(s):  
Juan Yang ◽  
Hong Bo Sun ◽  
Dan Li
Keyword(s):  
Sheet Resistance ◽  
Photoelectron Spectroscopy ◽  
Dip Coating ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Coating Method ◽  
Dip Coating Method ◽  
Dip Coating Technique

The graphene (GE) films were fabricated in this paper through the deposition of graphene oxide (GO) sheets onto the quartz slide by means of dip-coating technique, followed by thermal annealing. The growth process and transmittance of the film were monitored by ultraviolet and visible spectrophotometer (UV-Vis), the surface morphology and structure were investigated by Atomic force microscopy (AFM), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman. The sheet resistance of the film was also tested and results showed that the sheet resistance is about 60 kΩ-1and the transmittance is as high as 81 % (at 550 nm).

Nucleation Mechanism for Epitaxial Graphene on Si-Terminated SiC (0001) Surfaces

2011 ◽  
Vol 338 ◽  
pp. 530-533
Author(s):  
Qing Bin Liu ◽  
Jia Li ◽  
Jing Jing Wang ◽  
Shao Bo Dun ◽  
Zhi Hong Feng
Keyword(s):  
Epitaxial Graphene ◽  
Nucleation Mechanism ◽  
Raman Scattering Spectrum ◽  
Force Microscopy ◽  
Atomic Force ◽  
Graphene Films ◽  
Scattering Spectrum ◽  
Initial Nucleation ◽  
Decomposition Time ◽  
Substrate Surfaces

The nucleation mechanism during the epitaxial graphene films on Si-terminated SiC (0001) surfaces was investigated by atomic force microscopy (AFM) and Raman scattering spectrum. By imaging the change of Si-terminated SiC substrate surfaces, we observed the process of the initial nucleation and the wrinkle formation of graphene. The nucleation of epitaxial graphene phase initiates at 1450°C and the wrinkle formation depends on the thermal decomposition time.

scholarly journals Magnesium-Free Immobilization of DNA Origami Nanostructures at Mica Surfaces for Atomic Force Microscopy

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4798
Author(s):  
Yang Xin ◽  
Amir Ardalan Zargariantabrizi ◽  
Guido Grundmeier ◽  
Adrian Keller
Keyword(s):  
Atomic Force Microscopy ◽  
Single Molecule ◽  
Pure Water ◽  
Dna Origami ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Individual ◽  
Individual Strategies ◽  
Phosphate Buffered Saline

DNA origami nanostructures (DONs) are promising substrates for the single-molecule investigation of biomolecular reactions and dynamics by in situ atomic force microscopy (AFM). For this, they are typically immobilized on mica substrates by adding millimolar concentrations of Mg2+ ions to the sample solution, which enable the adsorption of the negatively charged DONs at the like-charged mica surface. These non-physiological Mg2+ concentrations, however, present a serious limitation in such experiments as they may interfere with the reactions and processes under investigation. Therefore, we here evaluate three approaches to efficiently immobilize DONs at mica surfaces under essentially Mg2+-free conditions. These approaches rely on the pre-adsorption of different multivalent cations, i.e., Ni2+, poly-l-lysine (PLL), and spermidine (Spdn). DON adsorption is studied in phosphate-buffered saline (PBS) and pure water. In general, Ni2+ shows the worst performance with heavily deformed DONs. For 2D DON triangles, adsorption at PLL- and in particular Spdn-modified mica may outperform even Mg2+-mediated adsorption in terms of surface coverage, depending on the employed solution. For 3D six-helix bundles, less pronounced differences between the individual strategies are observed. Our results provide some general guidance for the immobilization of DONs at mica surfaces under Mg2+-free conditions and may aid future in situ AFM studies.

Studies of Multiwall Carbon Nanotubes Using Raman Spectroscopy and Atomic Force Microscopy

2004 ◽  
Vol 99-100 ◽  
pp. 265-268 ◽  
Author(s):  
M. Zdrojek ◽  
W. Gebicki ◽  
C. Jastrzebski ◽  
T. Melin ◽  
A. Huczko
Keyword(s):  
Carbon Nanotubes ◽  
Low Frequency ◽  
Multiwall Carbon Nanotubes ◽  
Radial Breathing Mode ◽  
Force Microscopy ◽  
Disorder Effects ◽  
Atomic Force ◽  
New Feature ◽  
Single Wall Nanotubes ◽  
Multiwall Carbon

Preliminary results of Raman scattering measurements of multiwall carbon nanotubes (MWCNT) are presented. The nanotubes have been carefully dissolved, separated and then characterized by AFM. The micro-Raman spectra are taken with 514,5nm wavelength excitations in the range 4K - 400K. Basically the spectra are quite similar to the well known single wall carbon nanotube spectra, but the low frequency band is absent. The major Raman bands, observed in single wall nanotubes are found in the spectra. In particular the disorder effects are visible due to the pronounced D band at ~1350 cm-1. Metallic and semiconducting type of conductivity is distinguished through analysis of the G (LO) mode at ~1600 cm-1. A new feature in these spectra exists at ~843 cm-1. Low energy radial breathing mode absence has been explained.

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