電化學分析法是一種簡單、快速、具有高敏、低偵測極限的分析工具，因為現今電子及半導體工業發達，使得電化學分析儀器造價相對於其他常用的光學分析法儀器宜，而且體積可大為縮小，如現今市面上已經廣為醫學界使用之電化學血測定儀，即是一。本研究將玻碳工作電極經初步表面研磨處後，以電化學修飾法將其活化，再用此活化電極對以三極式電化學方式於玻璃碳電極表面沉積金微粒與幾丁聚醣高分子薄膜，進行多巴胺生物感測器的偵測觀察，並與未經電化學修飾法活化的玻碳工作電極分析結果進比較，以驗證本電化學修飾法活化玻碳電極的功效。除電拋光表面處理和高分子薄膜的討論，另外藉由五種不同碳鏈長短的自組裝高分子，來說明官能基與修飾物碳鏈長短對待偵測物的影響。實驗結果顯示於拋光處理後的電極表面對待偵測物質有著極高的效應，添加幾丁聚醣於表面修飾，可提高多巴胺的偵測極限，加上幾丁聚醣本身具有相當優秀的生物相容性，容易分解極具環保，對於生物感測器上的運用，是很好的概念延伸。此外，藉由cysteamine, 4,4’-Dithiodibuttersaure和16-Mercaptohexadecanoic acid等自組裝高分子的表現推論，表面官能基與碳鏈愈短的鍵結對多巴胺生物偵測的偵測愈有利。
Dopamine (DA) is one of the most significant catecholamine and widely distributed in the brain. Changes of DA concentrations in biological samples may lead to serious diseases such as Parkinson’s. Detection of DA in the physiological environment has been a great challenge. The DA concentration is only a nanomolar to micromolar range (0.01–1 μM) in extracellular fluids. In addition, uric acid (UA) is the primary end product of purine metabolism. Ascorbic acid (AA) is a vital vitamin in the diet human. Among animal organs, AA is generally much higher than of DA (100 to 1000 times, about 100-500 μM). Since AA, DA and UA usually coexist in physiological samples. These species which oxidize at bare electrodes in the same potential region as DA, which results in overlapped voltammetric responses.
The objective of the study was to evaluate the dopamine electrochemical biosensor of chitosan modified glassy carbon electrode (GCE) for selective determindation of dopamine (DA) in the present of UA and AA was described. The results indicated that the modified electrode successfully decreased the overlapped voltammetric responses and improved the electrocatalytic activity for DA, AA and UA detection. In addition, the electrocatalytic activity of GCE for DA detection in the present of AA and UA could be achieved by easy pretreatment in acidic solutions. The electrochemical measurements of csteamine, 4,4’-Dithiodibuttersaure and 16-Mercaptohexadecanoic acid self-assembly may provide an differences electron transfer rate. It is high selectivity for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA).
