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|Title:||Graphene-based materials for biotransistor application||Authors:||Ng, Wei-Beng||Keywords:||DRNTU::Engineering::Bioengineering||Issue Date:||31-Dec-2018||Source:||Ng, W.-B. (2018). Graphene-based materials for biotransistor application. Doctoral thesis, Nanyang Technological University, Singapore.||Abstract:||A biomimetic cell membrane bioelectronic transistor consisting of a supported phospholipid bilayer atop chemical vapor deposition (CVD) graphene or solution processed reduced graphene oxide on titanium dioxide (TiO2) has been successfully demonstrated for biosensing application. For the first time, a unique bonding interaction between titanium and carbon atom on graphene oxide has been experimentally identified by X-ray Photoelectron Spectroscopy (XPS). The covalent interaction acts as a strong surface anchorage in facilitating uniform adhesion and near to ideal surface coverage of spin coated graphene oxide on titanium bearing substrate using the in-situ solid-liquid phase exfoliation method. The liquid gated Reduced Graphene Oxide (RGO) biotransistor is sensitive to environmental changes in ionic strength of liquid environment by shift in electrical output signals at a sensitivity level of ~0.030mA per millimolar at gate bias VG=-8V and 0.035mA per millimolar at drain bias VD=1V. Incorporation of a phospholipid membrane atop the RGO transformed the sensing transistor to a bioelectronic transistor capable of sensing attached biomolecules on functionalized lipid/RGO surface acting as pseudo gate bias which modulated the electrical signals output. Supported neutral and charged lipid membranes on RGO at active source-drain region were formed by solvent assisted lipid bilayer (SALB) formation. A modulation of transistor conductance induced by gate charges were observed by the measurement of transistor drain current. Based on the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/RGO biotransistor platform, a functional supported lipid bilayer (SLB) was demonstrated using biotin-streptavidin binding event. The quantification of biotin composition with respect to transistor drain current modulation was monitored which showed a linear relationship between the percentage of changes in drain current versus the percentage of biotin composition in the complex SLB. For instance, a 12% change in drain current was measured for a 1wt % biotinylated DOPC lipid complex membrane upon streptavidin binding. The results illustrated the potential of using lipid bilayer as an efficient biofunctionalization tool on graphene oxide as a highly versatile and sensitive biosensing platform for a variety of receptor-ligand binding events.||URI:||https://hdl.handle.net/10356/89327
|DOI:||https://doi.org/10.32657/10220/47698||Fulltext Permission:||open||Fulltext Availability:||With Fulltext|
|Appears in Collections:||IGS Theses|
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|PhD Final Thesis Graphene Based Materials for Biotransistor Application.pdf||PhD Thesis Final Version||4.33 MB||Adobe PDF|
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