Fabrication of nanostructured copper electrodes for the detection of amino acids

• Main Authors: Ming-Yuan Lee, 李名袁
• Other Authors: Jin-Chyau Peng
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/78478278032706391981

博士 === 國立中興大學 === 電機工程學系所 === 102 === Abstract This dissertation elucidates the fabrication of copper-nanostructured electrodes by electrodepositing techniques and their applications in thedetection of amino acids (AAs). The topics include: (1) geometric effect ofcopper nanoparticles (CuNPs) electrodeposited on screen-printed carbonelectrodes (SPEs) on the detection of α-, β- and γ-amino acids (AAs); (2) fabrication of nanostructured copper phosphate (Cu3(PO4)2) electrodes forthe detection of α-amino acids; (3) effect of ionic liquid (IL) on thedetection of AAs measured at the nanostructured-Cu3(PO4)2 electrodes in aweak alkaline solution. The contents of each chapter are listed below: Part 1： Geometric effect of copper nanoparticles electrodeposited on screen-printed carbon electrodes on the detection of α-, β- and γ-amino acids Disposable copper nanoparticle electrodeposited screen-printed carbon electrodes (CuNPs/SPEs) capable of detecting α-, β- and γ-amino acids(AAs) are developed by a process which alternates reductive deposition and oxidative treatment over six cycles (called the RO6 method). Compared with other electrodepositing methods, the 87% ratio of RO6 method-depositing CuNPs is cubic in shape with an average edge length of 353 nm, and features a relatively higher CuI2O(200) to CuIO face ratio of 0.17. The particular geometric characteristics of RO6-CuNPs/SPEs permit varied AA ligands to form complexes with CuI and CuII at around 0.0 V and +0.2 V, respectively. Moreover, the oxidative current induced by the CuII-AA ligand complex is larger than that induced by the CuI-AA ligand complex. Furthermore, α-AAs exhibit the faster complexation rate than β-alanine and γ-aminobutyric acid, resulting in a larger current response. The RO6-CuNPs/SPEs integrated with a flow injection analysis system exhibits high reproducibility with a relative standard deviation of 2.68%,and good linearity (correlation coefficient > 0.995) in the range of 5–1000μM. The RO6-CuNPs/SPEs promise excellent potential for the integration of separation system to provide sensitive analysis of α-, β- and γ-AAs in clinic diagnostic and food industry applications. Part 2： Fabrication of nanostructured copper phosphate electrodes for the detection of α-amino acids Cu3(PO4)2-deposited electrodes capable of detecting nonelectroactive α-amino acids (AAs) are developed by the dissolution-precipitation method. The Cu3(PO4)2-dominated compounds of flake-shape nanostructures can bequickly and uniformly deposited on the surface of acicula-nanostructured Cu(OH)2-electrodeposited electrodes in a 100 mM Na2HPO4 solution (pH5.0) within 2 h. Analysis of X-ray photoelectron spectroscopy andelectrochemical kinetics showsan oxidative reaction at +0.11 V can increase the ratio of H2PO41- on the electrode surface andproduce theCuII(H2PO4)2 complex. Moreover, the CuII compounds and the AAs can form complexes to accompany the chemical oxidation of AAs and the formation of the CuI complex, increasing the amount of oxidative current detected via the chemical-electrochemical mechanism. The amperometric response presented good linearity and sensitivity in the range of 143–600μM for electroactive and nonelectroactive α-AAs. The Cu3(PO4)2-deposited electrode can act as a promising AA sensor for applications in the biomedical diagnostics and food industries. Part 3： Ionic liquid-modified copper phosphate electrodes for the detection of α-amino acids in weakly alkaline solution The N-propyl-3-methylpyridinium bis(trifluoromethanesulfonyl) imide (PMP-TFSI) IL-modifed Cu3(PO4)2-deposited electrodes are used to detect electroactive and nonelectroactive α-AAs in a weakly alkaline solution. The SEM images show that the PMP-TFSI IL can cover the entire surface of Cu3(PO4)2-deposited electrodes. The electrodes displayed an obvious oxidative peak at +0.11 V in a 20 mM Na2HPO4 solution (pH 7.4). Moreover, the result of electrochemical kinetics showed that two-electron tansfer occurred, resulting from the formation of CuIIHPO4 complex due to the oxidation of HPO42- on the electrode surface. The amperometric response presented good linearity and sensitivity in the range of 90.9–500.0μM for electroactive and nonelectroactive α-AAs.The IL/Cu3(PO4)2-deposited electrodes improve the drawback of previous Cu3(PO4)2 electrodes to promise the AA meassurement in alkaline solutions and lower the LOD.