人口的老化已成為全世界嚴重的經濟挑戰。相對的，罹患阿茲海默症的人數也逐年 增加。阿茲海默症為神經退化性疾病，其腦部神經細胞受到破壞，造成病患在記憶力、 認知功能甚至語言表達及肢體動作等各方面的功能障礙。而目前尚未證實有藥物能恢 復已經受損的腦神經細胞，僅有針對患者提供減緩疾病惡化的藥物。另外，臨床顯示， 若能早期檢測出此疾病才能有助於提供患者延緩疾病惡化。然而，目前的診斷方式卻 侷限於醫院或是少數機構擁有的貴重儀器，且檢測的成本費用昂貴，無法普及一般社 會民眾而延誤疾病治療的時機。因此，我們致力於發展一個快速、簡便且又低成本的 檢測方式，希望未來能應用於採檢血液以及淚液做為檢體，檢測其中超微量的 β 澱粉 蛋白。而目前 β 澱粉蛋白 40 及 β 澱粉蛋白 42 為檢測阿茲海默症重要的生物標記。在 本研究中，我們使用電化學測量方式搭配低成本的一次性拋棄式電極應用於免疫感測 器中。藉由電阻抗量測系統以及其阻抗等效電路的應用，能夠量化極少量的 β 澱粉 蛋白濃度並得到一個建構於濃度變化上的標準曲線。此免疫感測器的偵測極限為 1 pg ml−1 ，具有相當的潛力應用於未來阿茲海默症之臨床檢測中。

Alzheimer’s disease is a severe progressive neurodegenerative brain disorder affecting elder population. The devastating illness cause an irreversible dysfunction in neuron while there is no proven cure for patients. Therefore, earlier diagnosis would provide an effective therapeutic treatment to ameliorate the process. The current medical diagnosis in Alzheimer’s disease is time-consuming and expensive with the limitation to special institutes or hospital. As the result, many patients do not get the proper diagnosis until the symptoms occur. The critical biomarkers in Alzheimer’s disease are two isoforms, Aβ(1–40) and Aβ(1–42). Therefore, we endeavor to investigate a rapid and low-cost method to quantify Aβ(1–40) and Aβ(1–42) at a level in blood and tears. We develop a immunosensor utilizing a screen-printed-electrode while electrochemi- cal instrument serves as the transduser. Based on the electrochemistry impedance spectroscopy technique, the quantitative signal of beta-amyloid is analyzed through an equivalent circuit and further conduct a concentration standard curve. The proposed sensor performs a limit of detec- tion (LOD) of 1pg ml−1 that could further be a promising diagnosis approach in Alzheimer’s disease.

摘要............................ ii
Abstract.......................... iii
Acknowledgement .................... iv
Table of Contents ..................................... v
List of Figures ....................................... vii
List of Tables........................................ ix

1 Introduction....................................... 1
. 1.1  Background-Alzheimer’sdisease ........................ 1

. 1.2  Diagnosisapproach................................ 2

. 1.3  Motivation..................................... 3

. 1.4  ConceptualFramework.............................. 4

2 PrincipleandTheoreticalFramework ........................ 5
. 2.1  Overviewofelectrochemicalsystems ...................... 5

. 2.2  Electrochemicalcellandreactions ........................ 6

. 2.3  CyclicVoltammetry................................ 8
2.3.1 Reversiblesystems............................ 10
2.3.2 Irreversiblesystems ........................... 12

. 2.4  ElectrochemicalImpedanceSpectroscopy(EIS) . . . . . . . . . . . . . . . . . 13
2.4.1 IntroductiontoEIS............................ 13
2.4.2 Linearitypropertyofthesystem ..................... 15
2.4.3 ExpressionofImpedance......................... 16

3 MaterialandMethodology............................... 19
. 3.1  ExperimentalChemicals .......................... 19

. 3.2  ExperimentalApparatus .......................... 20

. 3.3  Experimentmethodology........................... 20

3.3.1 Characteristic of screen-printed-electrode . . . . . . . . . . . . . . . . 20
3.3.2 Surface modification of self-assembly monolayer . . . . . . . . . . . . 21
3.3.3 Crosslinkreagent............................. 24
3.4 Experimentprocedure............................... 28
. 3.4.1  Experimentoverview........................... 28

. 3.4.2  Electrodetreatmentandinstrumentsetup . . . . . . . . . . . . . . . . 29

. 3.4.3  SAMformation.............................. 30

. 3.4.4  EDC/NHScrosslink ........................... 30

. 3.4.5  Antibody immobilization and blocking process . . . . . . . . . . . . . 31

. 3.4.6  Peptidepreparation............................ 32

4 ResultandDiscussion ................................. 33
. 4.1  Characterization of nanostructure configuration on SPEs . . . . . . . . . . . . 33

. 4.2  SAMmodificationwithtime-savingmethod................... 35

. 4.3  EDC/NHScrosslinklayer........................... 38

. 4.4  Antibody immobilization and the optimal concentration . . . . . . . . . . . . . 40

. 4.5  Quantitative Detection of Total Aβ(1-40) and Aβ(1-42) . . . . . . . . . . . . . 42

. 4.6  Resultofthebiomarker:Aβ40/42ratio ..................... 44

5 Conclusion ....................................... 46
References ......................................... 47

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