| Summary: | 碩士 === 國立中興大學 === 生醫工程研究所 === 104 === Since graphene was successfully isolated in 2004, it has received much attention and proceed with many research application owing to its high charge mobility, low background noise, high surface area, and biocompatibility property. In this study, the patterned-circuit silicon chips was first modified with by (3-aminopropyl) trimethoxysilane (APTMS), forming self-assembled monolayer which containing with amine groups. Then, the inherited oxygenated functional groups on solution-based graphene oxide (GO) were activated by 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-Hydroxysuccinimide (EDC/NHS) and further covalently conjugated with amine-functionalized silicon chips through amide bonds (-CONH-). After that, chemical reduction using hydrazine was implemented to remove a variety of oxygenated groups from immobilized GO surface gaining reduced GO (RGO). Electron spectroscopy for chemical analysis (ESCA), contact angle, Raman spectroscopy, biocompatibility test and I-V curve measurement were used to characterize the chemical components, hydrophilic/hydrophobic properties, lattice structure, biological toxicity and electrical characteristics of different reduced time of RGO. Analysis of results indicated 60-min RGO featured of optimal material properties which was suitable for the base material of the biosensors. Further, using 60-min RGO-based biosensor in the detection of the concentration gradient of dopamine. Making use of phosphate buffered saline to prepare dopamine solution, simulating physiological environment in human body. The medium frequency range of electrical impedance were measured by using LCR meter (E4980A, Agilent Technologies). Since the dopamine concentration in our cerebrospinal is around 1.89~16.65 nM, our 60-min RGO-based biosensor could discriminate 1 fM~100 nM which proved that 60-min RGO biosensor could be as the effective sensing dopamine platform. Furthermore, through the change in the impedance value could observe proliferation condition of rat adrenal pheochromocytoma (PC12) cells, proved 60-min RGO biosensor also could be non-invasive monitoring of living cells platform. By adding nerve growth factor (NGF) to stimulate PC12 cells differentiation, along with synapses growth and exhibited neuron characteristics. With 100μM KCl stimulation, neurotransmitters would be released from synaptic vesicle in differentiated PC12 cells. Through 60-min RGO biosensor could measure the impedance change which resulted from attachment of differentiated PC12 cells or emancipation of dopamine. In this research, through LCR meter imposing a sinusoidal AC voltage to trigger disturbances of frequency, avoiding hydrazine-reduced 60-min RGO biosensor to be interfered by Debye length. According to impedance response of dopamine and cell physiology, 60-min RGO biosensor could be used to detect early symptoms of imbalance dopamine concentration which related to Parkinson''s disease or schizophrenia, showing promising application in detection and tracking of the lesion.
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