Reduced graphene oxide-multi walled carbon nanotubes hybrid material as electrode for DNA biosensor
This thesis presents a novel thin film of reduced graphene oxide-multiwalled carbon nanotubes (rGO-MWCNTs) composites as a sensing film electrode for Deoxyribonucleic acid (DNA) immobilization and hybridization detection. This project consisted of three parts, which are the rGO-MWCNTs composite t...
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| Format: | Thesis |
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| Language: | English |
| Subjects: | |
| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77997/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77997/2/Full%20text.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/77997/4/Saeed%20Salem.pdf |
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| Summary: | This thesis presents a novel thin film of reduced graphene oxide-multiwalled carbon
nanotubes (rGO-MWCNTs) composites as a sensing film electrode for Deoxyribonucleic
acid (DNA) immobilization and hybridization detection. This project consisted of three
parts, which are the rGO-MWCNTs composite thin film preparation and characterization,
the device fabrication processes description, and followed by the DNA immobilization
and hybridization. In the first part, the thesis describes the graphene oxide preparation
from graphite powder using improved Hummers’ method. Whereas, the multiwalled
carbon nanotubes (MWCNTs) was functionalized through nitric acid oxidation process.
Chemical reduction process was used to obtain the reduced graphene oxide using
hydrazine as reduced agent. The MWCNTs, GO, and rGO-MWCNTs materials were
mechanically sprayed on the silicon dioxide (SiO2) surface of the device channel using
spray technique. Chitosan solution was mixed with the materials and sprayed on the
device surface in order to increase the viscosity of the materials and strengthen their
adhesion with the silicon dioxide surface by changing the surface characteristic from
hydrophobic to hydrophilic. The morphology of the rGO-MWCNTs composite thin films
were observed by field emission scanning electron microscope. The bonding of the rGOMWCNTs
were examined using Fourier transform infrared spectroscopy. The phase
structure of the materials were confirmed via X-ray powder diffraction. Secondly, the
design, fabrication and evaluation of the device were descripted in details. In addition,
the device fabrication processes contained of oxidation process for silicon dioxide layer
growing, physical vapor deposition process which was used to deposit an aluminum layer
on the silicon substrate to form the source and drain, mask designed, printed, and utilized
in the pattern transfer process, and photolithography process which was carried out to
create the channel of the device. The operation of the electrode is based on the surface
charge adsorption of the film material interface. Finally, in the DNA immobilization and
hybridization section where the novelty of the research introduced, the biosensor
demonstrated high sensitivity to the complementary DNA target with a linear range from
500 pM to 100 pM. Furthermore, the biosensor demonstrated good selectivity,
reproducibility, and long-term stability for DNA detection. The device has shown
sufficient capability to distinguish between targets complementary DNA and different
DNA sequences, such as non-complementary and single-mismatched DNA. The
hybridization process of the non-complementary DNA has the smallest response (39 μA)
due to the double standard DNA was not effectively formed. Whereas, the singlemismatched
DNA has shown less response (55 μA) comparing with the complementary
DNA (65 μA) due to the single mismatched base. The device accuracy was investigated
and found to be 11.28 %. Since, the biosensor responded very well and demonstrated
excellent detection capabilities, it is highly recommended to be used in detecting specific
biomarkers and other targeted proteins. |
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