Detection of biomolecules is important for the diagnosis and treatment of diseases. Low concentration detection, specific biomolecule detection, and point-of-care use are appealing characteristics for biosensors because of the possibility of early detection and quick results of specific biomolecules. Furthermore, inexpensive biosensors are appealing so that they are accessible to the general population. The biosensors in this study have the potential to satisfy these characteristics.
In this study graphene field-effect transistors (G-FET) were fabricated. Graphene was grown using chemical vapor deposition (CVD) and transferred to a silicon/silicon oxide substrate. The CVD method is the most scalable and cost-effective method of producing graphene for devices. Standard photolithography was used to pattern and then deposit metal electrodes. Two separate experiments were conducted; one using electrostatic attraction to bind protein to the active area of the G-FET to detect the protein poly-L-lysine (PLL) and one using an aptamer modified G-FET to selectively detect the protein thrombin. Analyte was delivered using a homebuilt, pressure driven, microfluidic, mass flow system.
Both experiments showed a detection of the protein. The PLL experiment showed a clear change in the effective gate voltage of the G-FET. The thrombin experiment showed a change in the effective gate voltage that varied with differing concentrations of thrombin present. Furthermore, in the thrombin experiment by changing from a thrombin solution back to buffer the effective gate voltage was brought back to its original value. A competing protein was introduced and gave a signal comparable to the signal of a 10 times smaller concentration of thrombin. All of this shows that CVD grown graphene in a FET biosensor can be used for protein detection. Furthermore, the specific detection of thrombin suggests that aptamer modified G-FETs with CVD grown graphene can be used as a protein specific biosensor. / Graduation date: 2013
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33984 |
| Date | 19 September 2012 |
| Creators | Saltzgaber, Grant William |
| Contributors | Minot, Ethan D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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