咖啡酸官能基化奈米金-多壁奈米碳管複合材料修飾網版印刷碳電極對半胱胺酸之電化學分析

Electrochemical Determination of Cysteine Base on Screen-Printed Carbon Electrodes Modified with Caffeic Acid Functionalized Gold Nanoparticles-Multiwalled Carbon Nanotube Composites

林奕銘(Yi-Ming Lin)

指導教授 ： 鄭淑華

國立暨南國際大學/科技學院/應用化學學系/碩士(2021年)

https://doi.org/10.6837/ncnu202100281

摘要

半胱胺酸(cysteine)是人體內重要的胺基酸之一，過多或過少的含量將會導致身體的不適及病變；此外，半胱胺酸具有抗氧化的作用，能作為抗氧化劑添加在食品中，在法規中限制僅有麵包及果汁中可加入。本論文希望開發電化學的平台，能夠快速且靈敏的檢測保健食品中的半胱胺酸。
本研究是利用檸檬酸(citric acid)當作穩定劑及還原劑，製備奈米金(gold nanoparticle)與多壁奈米碳管(MWCNT)成複合材料，將製備完成的複合材料以滴塗(drop coating)的方式修飾到網版印刷碳電極(screen-printed carbon electrodes)，再將咖啡酸(caffeic acid)之羧酸基以醯胺鍵(amide bond)接枝至奈米金表面，完成複合材料修飾電極的製備。我們使用循環伏安法(Cyclic Voltammetry, CV)研究半胱胺酸在修飾電極的電化學反應；透過電極表面的咖啡酸官能基來傳遞電子，使得咖啡酸的氧化電流增加且還原電流下降，可利用咖啡酸的電流變化來作為偵測半胱胺酸之訊號來源。我們使用安培法(Chronoamperometry)偵測半胱胺酸，透過此方法修飾的電極具有偵測範圍0.4 μM至12 μM，靈敏度為0.2719 μA/μM，偵測極限為0.032 μM。

關鍵字

奈米金 ； 半胱胺酸 ； 咖啡酸 ； 網版印刷電極 ； 電化學偵測

並列摘要

Cysteine is one of the important amino acids in the human body. People with high or low level of cysteine will cause physical discomfort and pathological changes. Cysteine has an antioxidant effect, therefore it is used in medicine and added as food additives. According to the regulations, cysteine can be added in bread and juice only. In this thesis, an electrochemical cysteine assay is developed, and applied for the determination of cysteine in dietary supplement.
Citric acid is used as reducing and capping agent to synthesize nanocomposite materials containing gold nanoparticle and multiwalled carbon nanotubes (MWCNT). The nanocomposite materials are modified on the screen-printed carbon electrode (SPCE) by drop coating. Then, the carboxylic acid group of caffeic acid is grafted to the surface of the nanogold with an amide bond to achieve the modified electrode. The modified electrode is stabilized by cyclic voltammetry. An electrochemical oxidation reaction of cysteine is studied by cyclic voltammetry at the modified electrode, causing the oxidation current of the surface caffeic acid increases and the reduction current decreases. The current signal of caffeic acid is used to detect cysteine. Detection of cysteine is operated by chronoamperometry, and the analytical results have wide working range (0.4 μM-12.0 μM), a low detection limit (0.032 μM) and good selectivity (0.2719 μA/μM).

並列關鍵字

gold nanoparticle ； cysteine ； caffeic acid ； screen-printed carbon electrode ； electrochemical sensor

參考文獻

[1] P. Bin, R. Huang, X. Zhou, Oxidation resistance of the sulfur amino acids: methionine and cysteine, Biomed Res Int, 2017 9584932 (2017) 1-6.

[2] N. Clemente Plaza, M. Reig Garcia-Galbis, R.M. Martinez-Espinosa, Effects of the usage of l-cysteine (L-Cys) on human health, Molecules, 23 (2018) 323-575.

[3] B. Sameem, F. Khan, K. Niaz, L-cysteine, nonvitamin and nonmineral nutritional supplements, (2019) 53-58.

[4] T. Rehman, M.A. Shabbir, M. Inam-Ur-Raheem, M.F. Manzoor, N. Ahmad, Z.-W. Liu, M.H. Ahmad, A. Siddeeg, M. Abid, R.M. Aadil, Cysteine and homocysteine as biomarker of various diseases, Food Science & Nutrition, 8 (2020) 4696-4707.

[5] C.J.P. Eriksson, M. Metsälä, T. Möykkynen, H. Mäkisalo, O. Kärkkäinen, M. Palmén, J.E. Salminen, J. Kauhanen, L-cysteine containing vitamin supplement which prevents or alleviates alcohol-related hangover symptoms: nausea, headache, stress and anxiety, Alcohol and Alcoholism, 55 (2020) 660-666.