黃素腺嘌呤雙核甘酸/nano-TiO2、nano-TiO2/DNA/Thionin與Cunano/鄰苯二胺高分子薄膜的製備及其電催化性質的研究

Preparation, Characterization and their electrocatalytic properties of Flavin Adenine Dinucleotide/nanostructured TiO2, TiO2/DNA/Thionin Dye, copper nanoparticles included polymer film modified electrodes

羅博勳(Po-Hsun Lo)

指導教授 ： 陳生明 ； 呂光烈

國立臺北科技大學/工程學院/化學工程研究所/碩士(2008年)

摘要

本研究主要分為三部分來討論，第一部分為使用定電位法將奈米結構TiO2薄膜製備於網版碳電極及ITO導電玻璃上，再將黃素腺嘌呤雙核甘酸(FAD)固定於TiO2修飾電極上。黃素酵素穩固的依附在金屬氧化物的表面，且此修飾電極可對於過氧化氫產生相當大的電催化效果。使用電化學方法將FAD限制於氧化物薄膜內已被廣泛的研究了。固定於修飾電極上的FAD，顯示出有一對氧化還原波峰，在pH 7無氧的磷酸鹽緩衝溶液中形式電位為-0.42V，掃描速率為50mVs-1。在奈米結構TiO2內的FAD不但保持著其生化活性，且可催化還原過氧化氫。測量過氧化氫的線性範圍為1.0x10-5到2.0x10-4M，偵測極限為2.0x10-7M，雜訊比為3。此外，利用原子力顯微鏡及掃描式電子式顯微鏡進行表面分析，證明FAD/TiO2為奈米結構。其穩定度、再現性及生化感測器的選擇性也將被探討。
第二部分為介紹一簡單的方法，製備一含有奈米結構TiO2及去氧核糖核酸(DNA)生質結構物的修飾電極。首先，使用電化學合成的方法在玻璃碳電極上修飾奈米TiO2微粒，接下來，使用電化學沉積的方法，在已修飾Nano-TiO2的玻璃碳電極上製備DNA薄膜，再將Thionin(TN)修飾於此雙層薄膜的修飾電極上，由循環伏安法的結果，我們可知Thionin被穩固不可逆地修飾於電極上。利用X射線繞射分析儀、原子力顯微鏡及掃描式電子顯微鏡所得到的結果，我們可知TiO2微粒的組成主要為銳鈦礦，並且得知TN/DNA/Nano-TiO2為奈米級組成。在pH 1~13的範圍內，TN/DNA/Nano-TiO2有著良好地穩定性及可逆性。在中性的緩衝溶液中，TN/DNA/Nano-TiO2/GCE生化感測器展現了，對還原過氧化氫和氧氣都有著相當傑出的電催化活性。利用此生化感測器來監測過氧化氫，其線性關係的範圍相當寬廣，範圍為0.2~22.3mM，偵測極限為0.05mM (S/N=3)。另外，使用此修飾電極來測試市售含有過氧化氫的樣品，所得之結果也相當令人滿意。此生化感測器的穩定度及再現性也將詳細的被討論。
第三部分是將銅奈米微粒製備於高分子修飾電極上，當作過氧化氫之感測器，發現可以大大地提升其敏感度。利用線性掃描伏安法將Cunano微粒直接電沉積在已事先覆蓋有高分子的電極；鄰苯二胺(pOPD)利用電化學沉積於電極表面，當作Cunano微粒沉積的平面。pOPD及Cunano/pOPD複合物的結構和形態特性，我們利用X射線繞射儀、原子力顯微鏡及掃描式電子顯微鏡進行探討。在中性的條件下，研究Cunano/pOPD修飾電極直接對過氧化氫及氧氣的電催化還原之性質，與裸電極和只修飾pOPD的電極比較，確實地減小了過氧化氫及氧氣還原所需的過電壓，Cunano/pOPD修飾電極還原反應於-0.3V開始，利用此電位我們可以了解到Cunano/pOPD修飾電極對過氧化氫有著相當高的再現性及敏感性，我們可以得知在1µM到1.0mM的範圍內，過氧化氫的濃度對電流成線性關係，並且偵測極限為0.1µM (S/N=3)。故Cunano/pOPD複合物修飾電極對過氧化氫有著高敏感度、低工作電位、穩定且快速的電流感測，因此可能進一步地發展成不含酵素的過氧化氫感測器。另外Cunano/pOPD修飾電極展現了對亞硝酸鹽有著良好的電催化活性，和在酸性狀態下測量其濃度。

關鍵字

黃素腺嘌呤雙核甘酸 ； 電催化 ； 過氧化氫 ； 二氧化鈦 ； 氧氣 ； DNA ； 生化感測器 ； 奈米銅 ； 亞硝酸鹽

並列摘要

Part I：Nanostructured TiO2 films were prepared onto screen-printed carbon electrode (SPE) and indium tin oxide coated electrode (ITO) by using potentiostat method. Resulting, TiO2 film coated electrode used to immobilize flavin adenine dinucleotide (FAD). Flavin enzyme firmly attached onto metal oxide surface and this modified electrode showed promising electrocatalytic activities towards reduction of hydrogen peroxide (H2O2) in physiological condition. The electrochemistry of FAD confined in the oxide film was investigated. The immobilized FAD displayed a pair of redox peaks with a formal potential of −0.42 V in pH 7.0 oxygen-free phosphate buffers at scan rate of 50 mV s−1. The FAD in the nanostructured-TiO2 film retained its bioactivity and could catalyze the reduction of H2O2. The immobilized FAD exhibited excellent electrocatalytic response to the reduction of H2O2, based on which mediated biosensor for H2O2 was achieved. The linear range for determination of H2O2 was from 10×10−6 to 2.0×10−4M with a detection limit of 2.0×10−7M at a signal-to-noise ratio of 3. In addition, atomic force microscopy and scanning electron microscopy are used for surface analysis and results are revealed that the FAD/TiO2 films are nanostrctured. The stability, repeatability and selectivity of the biosensor were also discussed.
Part II：Here, we report a simple method for preparation of biocomposite electrode based on nanostructured titanium dioxide (TiO2) and deoxyribonucleic acid (DNA). First step, Nano-TiO2 particles were electrochemically synthesized and used for modification of Glassy carbon electrode (GCE). Second step, DNA layer was electrochemically deposited onto Nano-TiO2/GCE. This bilayer (DNA/Nano-TiO2/GCE) film modified electrode used for loading of thionin (TN) dye molecules, cyclic voltammetry results indicated that strong and irreversible loading of TN. X-ray diffraction analysis, atomic force microscope and scanning electron microscope results revealed that TiO2 particles are composed mainly of anatase and TN/DNA/Nano-TiO2 film layer is nanocomposite, respectively. TN/DNA/Nano-TiO2/GCE shows a stable and reversible redox peak in the pH range of 1- 13. In neutral buffer solution, TN/DNA/Nano-TiO2/GCE biosensor exhibited excellent electrocatalytic activity towards reduction of hydrogen peroxide (H2O2) and oxygen (O2). This biosensor employed for detection H2O2 in wide linear range between 0.2 – 22.3mM with detection limit of 0.05mM (S/N=3). In addition with, determination of H2O2 in real samples was carried out and satisfactory results were obtained. The stability and reproducibility for biosensor also discussed in detail.
Part III：Copper nanoparticles (Cunano) have been prepared on polymer template and applied for the fabrication of H2O2 sensor with highly enhanced sensitivity. Cunano particles were directly electrodeposited onto pre-polymer coated electrodes by linear sweep voltammetry. Poly(o-phenylenediamine) (pOPD) electrochemically deposited onto electrode surface as plat form for Cunano particles deposition. The structures and morphologies of pOPD and Cunano/pOPD nancompsoites were characterized by X-ray diffraction, atomic force microscopy and scanning electron microscopy. The direct electrocatalytic reduction of H2O2 and oxygen in neutral medium at Cunano/pOPD nanocompsoite modified electrodes has been investigated in detail. Compared to a bare pOPD modified and bare electrode, a substantial decrease in the overvoltage of the H2O2 reduction and O2 were observed at the Cunano/pOPD nanocompsoite modified electrodes with reduction starting at cc. -0.30 V vs. Ag/AgCl (saturated KCl). At an applied potential of -0.30 V, Cunano/pOPD nanocompsoite electrodes produce high and reproducible sensitivity to H2O2 with 0.49 mA/mmol dm23. Linear responses were obtained over a concentration range from 1µM to 1.0 mM with a detection limit of 0.1 µM (S/N = 3). The Cunano/pOPD nanocompsoite modified electrode allows highly sensitive, low working potential, stable, and fast amperometric sensing of H2O2, thus is promising for the future development of non-enzymatic H2O2 sensors. In addition with, Cunano/pOPD nanocompsoite electrode showed excellent electrocatalytic activity towards nitrite and employed for its detection in acidic medium.

並列關鍵字

Titanium Dioxide ； Hydrogen Peroxide ； Flavin Adenine Dinucleotide ； DNA modified electrode ； biosensors ； Copper nanoparticles ； polymer nanocomposite ； nitrite detection

參考文獻

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