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標題: | 硼氮共摻雜還原態氧化石墨烯在半胱氨酸及還原態菸鹼醯胺腺嘌呤二核苷酸的感測應用 Application of Boron and Nitrogen Co-doped Reduced Graphene Oxide as an Electrochemical L-Cysteine and NADH Biosensor |
作者: | I-Ting Chen 陳奕廷 |
指導教授: | 何國川(Kuo-Chuan Ho) |
關鍵字: | 碳材,化學修飾電極,摻雜,電化學式感測器,半胱氨酸,還原態菸鹼醯胺腺嘌呤二核?酸,還原態氧化石墨烯, Carbon material,Chemically modified electrode,Boron-nitrogen co-doping,Electrochemical sensor,Graphene,L-cysteine,Modified electrodes,NADH biosensor,Nicotinamide adenine dinucleotide,Non-enzymatic detection,Reduced graphene oxide, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 本論文選擇用不同的分子當作感測標的物,包含半胱氨酸(L-cysteine)以及還原態菸鹼醯胺腺嘌呤二核苷酸(NADH)兩種生物分子,並已經過硼氮共摻雜的石墨烯(BN-rGO)與Nafion®修飾的網印碳電極(SPCE)作為工作電極,進行電化學的一系列感測分析。
L-cysteine為人體必要的二十種氨基酸的其中之一,其在人體內的濃度約介於240~360 M之間它涉及人體內抗氧化劑的合成以及許多人體代謝、退化等疾病。NADH為人體許多生化反應的共觸媒,涉及人體能量貨幣ATP的合成、協助進行呼吸作用等重要功能。本文首次利用BN-rGO對於此兩種感測標的物進行電化學感測分析,並探討在不同的製備條件(不同的NH3體積百分比)下,所形成的不同硼氮摻雜比例對於整體感測效果的影響。 第四章主要論述BN-rGOs-Nafion®/SPCE工作電極對於L-cysteine的感測效果。循環伏安法(CV) 實驗顯示,在3% NH3體積百分比下所製成的 BN-rGO (3% NH3)-Nafion®/SPCE對於 在L-cysteine具有最佳的感測效果,此電極相對於未經硼氮摻雜的純石墨烯(Pristine rGO)以及1%, 10% NH3體積百分比下所製成的BN-rGO,具有更低的氧化峰值電位以及更高的氧化催化電流。感測環境的pH值也經過最佳化測試,並選用與人體最接近的pH 7.0作為感測的環境條件。電位掃描速率的分析結果顯示L-cysteine的電極催化反應為一擴散控制的反應機制,利用催化電流與掃描速率的平方根圖所得之迴歸直線斜率,求得L-cysteine之擴散係數為cm2/s。計時電流分析法利用瞬間電極表面電位的改變,得以對感測物進行定量分析,感測結果的線性區間介於10 ~ 1060 M (R2= 0.991),感測器靈敏度為20.7 μA/cm2-mM,偵測極限則為0.07 μM。本研究亦使用旋轉電極分析BN-rGO (3% NH3)相對於pristine rGO在標準異相電子傳遞速率常數(standard heterogeneous rate constant)以及電活性表面積(electroactive surface area)上的本質差異,研究結果顯示BN-rGO (3% NH3)在兩個參數上都有近約30%的增長,強而有力地證明了經過硼氮共摻雜過後的石墨烯,對於L-cysteine具有更好的電催化效果。干擾物測試方面,本研究探討尿酸(UA)、抗壞血酸(AA)、氯化鉀(KCl)、葡萄糖(glucose)、L-色氨酸(L-tryptophan)、L-酪氨酸(L-tyrosine)對於L-cysteine感測物的干擾影響程度,大多數的干擾物沒有太大程度的干擾,唯有葡萄糖因於人體的相對濃度高於L-cysteine非常多,即使在相同濃度下感測干擾不大,考量到此濃度差距後要應用於實務上仍存在挑戰。 第四章主要論述BN-rGOs-Nafion®/SPCE工作電極對於NADH的感測效果。NADH是一種轉遞質子(氫離子)的輔助因子,出現在細胞很多代謝反應中,用於構建新的細胞生成,抵抗自由基和DNA損傷,並在細胞內發送信號。本研究亦以NADH為標的物探討經過硼氮共摻雜的石墨烯與未經摻雜的石墨烯在 NADH定性與定量分析上的差異。CV結果顯示只有bare SPCE與BN-rGO (3% NH3)-Nafion®/SPCE對NADH具有電催化的效果,BN-rGO (3% NH3)-Nafion®/SPCE成功地降低了NADH的氧化峰值電位約729 mV,此數值在所有文獻中為第二大的降幅,除此之外氧化還原峰值間距(peak separation)、氧化電位以及催化電流上的電化學表現相較於bare SPCE均有較佳的表現。感測環境的pH值也經過最佳化測試,並選用與人體最接近的pH 7.0作為感測的環境條件。電位掃描速率的分析結果顯示NADH的電極催化反應為一擴散控制的反應機制,利用催化電流與掃描速率的平方根圖所得之迴歸直線斜率,求得NADH之擴散係數為cm2/s,藉由此擴散係數數值,我們得以利用Velasco equation計算出標準異相電子傳遞速率常數(standard heterogeneous rate constant)。結果顯示bare SPCE及BN-rGO (3% NH3)-Nafion®/SPCE的異相電子傳遞速率常數分別為 以及,BN-rGO(3% NH3)-Nafion®/SPCE電極表面具有更好的電催化效果。電流分析法對於NADH感測的結果顯示,線性區間介於5~140 M (R2= 0.999),靈敏度為424 μA/cm2-mM,偵測極限則為0.03 μM,均屬所有可尋文獻中表現傑出者。干擾物測試方面,本研究探討尿酸(UA)、抗壞血酸(AA)、多巴胺(DA)、葡萄糖(glucose)、過氧化氫(H2O2)對NADH的干擾影響程度。此系統在進行NADH感測時,不會受到上述五種常見共存於人體中的干擾物影響,顯示此電極在作為NADH的感測電極時,有很大的潛力能應用於實務上。 In this thesis, boron and nitrogen co-doped reduced graphene oxide with different dopant composition were prepared as the electrochemical sensing platform. L-cysteine (CySH) and the reduced form of nicotinamide adenine dinucleotide (NADH) were selected as the sensing targets. The fabrication of BN-rGOs involved an atmospheric-pressure substitution reaction in the presence of boron oxide (B2O3) vapor and different volume percentage (1%, 3%, 10%) of ammonia gas. The surface morphologies were examined by transmission electron microscope (TEM). The composition and distribution of the dopants on BN-rGOs were verified by X-ray photoelectron spectroscopy (XPS) and energy-filtered transmission electron microscopy (EFTEM) elemental mapping. BN-rGOs were dispersed and drop casted onto the commercial screen printed carbon electrode (SPCE) to make the working electrode of the sensing system. BN-rGO (1% NH3)-Nafion®/SPCE, BN-rGO (3% NH3)-Nafion®/SPCE, BN-rGO (10% NH3)-Nafion®/SPCE and pristine rGO-Nafion®/SPCE were prepared as the working electrodes. L-cysteine (CySH), a thiol containing amino acid, plays a critical role in regulating the biological activity of certain proteins, peptides and enzymes and involves in a great variety of biological processes. CySH deficiency leads to slow growth in children, hair depigmentation, lethargy, liver damage, loss of muscle and fat, skin lesions, and weakness. From the results, BN-rGO (3% NH3)-Nafion®/SPCE among all the prepared electrodes showed the best electro-catalytic activity toward the electro-oxidation of CySH. It not only showed a decrease in oxidation potential but also an increase in catalytic peak current density of the CySH oxidation reaction with respect to the case of pristine rGO-Nafion®/SPCE. The quantification of CySH by chronoamperometric method could be successfully carried out by using BN-rGO (3% NH3)-Nafion®/SPCE. The sensing parameters included a wide linear range from 0.01 to 1.06 mM, a high sensitivity of 20.7 μA/cm2-mM, and a remarkable low detection limit of 0.07 μM. Rotating disk electrode analysis revealed a 30% increase in electroactive surface area (Ae) and the standard heterogeneous rate constant (k0), which is a powerful evidence accounting for a better electro-catalytic performance of BN-rGO (3% NH3)-Nafion®/SPCE. The system also showed acceptable resistance toward most of the coexisting interference in human serum such as L-tryptophan, L-tyrosine, potassium chloride, glucose, and uric acid. Reduced form of nicotinamide adenine dinucleotide (NADH) is the most important biological molecule in all living cells acting as a metabolic coenzyme in human body. It has been attributed to the transfer of hydrogen atoms and electrons from one metabolite to another in several intracellular redox reactions, such as glycolysis, the Krebs cycle, and oxidative phosphorylation. BN-rGO (3% NH3)-Nafion®/SPCE showed a unique electro-catalytic ability toward the electro-oxidation of NADH in pH 7.0 PBS, demonstrating a semi-reversible NADH/NAD+ redox peak at around -0.15 V and -0.95 V vs. Ag/AgCl. BN-rGO (3% NH3)-Nafion®/SPCE could also be successfully applied to the quantification of NADH by amperometric method. The sensing parameters include wide linear range from 5 to 140 μM, a high sensitivity of 424 μA/cm2-mM, and a remarkable low detection limit of 0.03 μM. The standard heterogeneous rate constant (k0) of pristine rGO-Nafion®/SPCE, pristine rGO and BN-rGO (3% NH3) were evaluated by Velasco equation, demonstrating a unique electro-catalytic ability and relatively facile electron transfer rate at the surface of BN-rGO (3% NH3)-Nafion®/SPCE. The system resisted most of the coexisting interference in human serum including ascorbic acid, uric acid, dopamine, glucose, and hydrogen peroxide and possessed a good long-term stability. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67484 |
DOI: | 10.6342/NTU201702356 |
全文授權: | 有償授權 |
顯示於系所單位: | 化學工程學系 |
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