الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Carbon nanomaterials, such as carbon nanotubes, C60, graphene oxide, and graphene, have attracted a lot of attention during the last couple of decades due to their unique properties that allow them to be used in several applications.
In this work, we aim to develop a biosensor based on graphene films. Both reduced graphene oxide (rGO) and graphene nanoplatelets (GP) have been used to form graphene films, followed by a series of characterization methods to achieve the best quality films.
To form the films, several methods were used such as DROP casting, dip coating, and spin coating. Spin coating was proved to be the best method to obtain the desired rGO and graphene nanoplatelets thin films.
For further develop the sensor, graphene-gold nanoparticles hybrid films were formed and studied. Gold nanoparticles (GNPs) are metal nanoparticles that can be used for sensing because of surface plasmon resonance and high electrical conductivity.
Gold Nano-Spheres (GNS), which are one of the shapes of GNPs, are widely used because of easy preparation method using Citrate, which can be used for making monolayers of GNPs. GNPs monolayers can be self-assembled on different substrates like glass, polymers, quartz, silicon, or ITO, using different deposition techniques such as spin coating, dipping by one side, DROP casting, and radiation.
In this work, deposition of GNPs was performed on glass substrates through DROP casting, annealing at different temperatures, and e-beam evaporation. GNPs were prepared using cetyltrimethylammonium bromide (CTAB) as a capping agent. CTAB, unlike citrate, causes the GNPs to be positively charged. The GNPs were then functionalized by a thiol-terminated compound. The thiolated samples were measured before and after annealing using a UV-VIS spectrophotometer.
The procedure was repeated on the citrate GNPs by using DROP casting and annealing which proved that annealing is better for self-assembly of GNPs. E-beam evaporation was used as a deposition technique to make gold nano-islands which was converted into GNPs by annealing at 300°C for 30 mins.
To obtain a hybrid film, GP was spin coated on the annealed gold nanoislands. The hybrid films were characterized electrically by using capacitance-voltage (C-V) measurement and optically by UV-VIS spectroscopy, Raman and SEM.
The hybrid was used as a pH sensor and the sensitivity, stability, and durability were measured and analyzed using C-V measurement which proved that the hybrid achieved higher sensitivity than that of GP alone