聚乙二醇修飾之石墨烯場效電晶體在高鹽度溶液偵測多巴胺

Using Polyethylene glycol-Modified Graphene-Based Field-Effect Transistor To Detect Dopamine in high salt solution

魏銘諒(Ming-Liang Wei)

指導教授 ： 陳逸聰

國立臺灣大學/理學院/化學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201800605

摘要

多巴胺(dopamine, DA)是重要的神經傳導物質，負責神經細胞的訊息傳遞，並且與許多疾病有關。然而，在這些病患血液或尿液中，多巴胺的濃度非常低，而現有的電化學感測器對多巴胺的偵測不夠靈敏，要用於檢測這些疾病是非常困難的。在本研究中，我們利用單層石墨烯(graphene)來製備場效電晶體生物感測器(field-effect transistor biosensor)，在場效電晶體上修飾去氧核醣核酸適體(DNA-aptamer)，建構出一個高靈敏度感測器。
自石墨烯被發現以來，它的高載子遷移率、高化學穩定性、高導熱、高導電性、可撓性、高機械強度，以及高透光率，使它受到許多領域的研究，它所具有的廣泛應用性也備受關注，因此本研究以單層石墨烯在石英基板表面製成場效電晶體來偵測低濃度多巴胺。
在使用石墨烯場效電晶體偵測多巴胺時，會遇到德拜-休克耳屏蔽效應(Debye-Hückel screening effect)的問題，即因為溶液的鹽離子濃度過高，使多巴胺的電場被離子屏蔽，導致偵測困難，在此我們使用聚乙二醇(polyethylene glycol)來克服，在石墨烯場效電晶體表面修飾聚乙二醇，減少德拜-休克耳屏蔽效應，使多巴胺的電場可以被石墨烯場效電晶體偵測到。本研究可以做到在高鹽度的溶液中偵測到10-9 M的多巴胺，並嘗試偵測稀釋後的胎牛血清，此高靈敏度感測器可提供一個新的生物感測平台，未來可應用在人體血液、尿液，即時偵測與多巴胺異常相關的疾病。

關鍵字

多巴胺 ； 石墨烯 ； 場效電晶體 ； 生物感測器 ； 德拜-休克耳長度屏蔽效應 ； 聚乙二醇

並列摘要

Dopamine is an important neurotransmitter, which is responsible for the transmission of nerve cells and is also associated with many diseases of nervous system. However, the existing electrochemical sensors are not sensitive enough to detect the trace amount of dopamine in human blood or urine. Hence, an ultra-sensitive biosensor to detect dopamine-related neurologic diseases at an early stage is needed.
Field-effect transistors have been studied with its sensitive biosensing applications over a decade. Besides, graphene has represented great potential in scientific research with its high carrier mobility, high chemical stability, high thermal conductivity, high conductivity, flexibility, high mechanical strength, and high light transmittance. Therefore, in this study, we fabricated graphene-based field-effect transistors (G-FETs) with single-layered graphene on the quartz substrate and modified DNA-aptamer on the G-FET surface to detect low concentrations of dopamine.
One major challenge of FET-based biosensors is to detect analyte in a high salt buffer. In term of Debye-Hückel screening effect, the electric-field of analyte is attenuated by ions and results in reduced signals. To overcome this problem, we modified polyethylene glycol (PEG) on the surface of a G-FET to decrease Debye-Hückel screening. With the capability of detecting 1 nM dopamine in 3× PBS solution, we proved that G-FETs can be employed as a highly sensitive biosensing platform for dopamine detection.

並列關鍵字

dopamine ； graphene ； field-effect transistor ； biosensor ； Debye-Hückel screening effect ； polyethylene glycol

參考文獻

1. Geim, A. K.; Novoselov, K. S., The rise of graphene. Nat Mater 2007, 6 (3), 183-91.

2. Mermin, N. D., Crystalline Order in Two Dimensions. Physical Review 1968, 176 (1), 250-254.

3. Wallace, P. R., The Band Theory of Graphite. Physical Review 1947, 71 (9), 622-634.

4. Morgan, A. E.; Somorjai, G. A., Low Energy Electron Diffraction Studies of Gas Adsorption on Platinum (100) Single Crystal Surface. Surf Sci 1968, 12 (3), 405-&.

5. May, J. W., Platinum Surface Leed Rings. Surf Sci 1969, 17 (1), 267-&.