在本論文中，利用中孔碳作為酵素載體，固定尿素酵素製備成電流式尿素生化感測器，探討製備所得酵素電極之性質及其感測特性。再藉由汞離子對尿素酵素活性具有抑制作用的特點，利用尿素酵素電極製備成電流式汞離子生化感測器。
以直接合成法製備中孔碳材，所得碳材主要孔徑為9.2 nm、表面積為853 m2g-1與孔洞體積為1.37 m3g-1。以電化學法聚合製備聚苯胺- Nafion複合膜/Au/Al2O3電極，並於複合膜電極上澆鑄中孔碳漿料與黏著劑Nafion溶液，可製備得Nafion/中孔碳/聚苯胺- Nafion複合膜/Au/Al2O3複合電極，並對銨根離子進行感測，發現此電流式的銨根離子感測器具有三段線性區域，濃度範圍為0.05~0.1、0.1~1與5～100 mM之間，其靈敏度分別為5400、390與21.9 µA mM-1 cm-2，其感測極限為0.05 mM。
隨後在中孔碳上固定尿素酵素，藉由尿素酵素催化尿素水解後產生的銨根離子來定量尿素之濃度。發現以使用澆鑄法固定2.12 U之尿素酵素於上述之複合膜電極時，在25 ℃與pH 6.88的磷酸鹽緩衝溶液(Phosphate buffer solution,PBS)環境下，對10 mM之尿素具有最大淨還原波峰電流值為417 µA，且在尿素濃度範圍為0.01~0.05 mM之間，還原波峰電流與尿素濃度具有線性關係，其靈敏度與感測極限分別為3595 µA mM-1 cm-2與0.005 mM。
以Nafion/urease(2.12 U)/中孔碳/聚苯胺-Nafion/Au/Al2O3作為感測電極，在5 ppm汞離子之感測溶液中，酵素電極喪失了58%的酵素活性，在汞離子濃度範圍為0.01~0.1 ppm之間，其感測靈敏度為5400 µA ppm-1 cm-2，感測下限則為0.005 ppm。
在中孔碳酸處理的研究中，利用體積比為3比1之濃硫酸與濃硝酸混合酸液對中孔碳進行修飾，使其具有親水性之羧基；從BET分析中得知，在常壓環境下，當酸處理時間由0增加到60分鐘，中孔碳表面積由853下降至431 m2g-1，且在減壓環境下進行酸處理，將會進一步破壞其孔洞結構。
利用常壓環境下酸處理15分鐘所得之中孔碳與減壓含浸-澆鑄法固定酵素，製備成為Nafion/urease(2.12 U)/中孔碳/聚苯胺- Nafion複合膜/Au/Al2O3電極，此時對酵素活性有最佳的保存效果。 In this study, urea biosensors were fabricated by the immobilization of urease on OMC. The effects of fabricated methods on the sensing characteristics of urea biosensor were investigated. Urea biosensor was used to detect the heavy metal ions due to the inhibition of enzymatic activity. OMC was prepared using a one-step synthesis method as the supports of enzyme. The surface area of OMC was found about 853 m2g-1. The major pore size of OMC was about 9.2 nm. The pore volume of OMC was about 1.37 m3g-1. The Nafion?/OMC/PANI-Nafion?/Au/Al2O3 sensors prepared by electrochemical polymerization and casting were used to detect the ammonium ion (NH4+). The three linear relationships between sensing current and the concentration of NH4+ were found in the range of 0.05~0.1、0.1~1 and 5?100 mM with the sensitivities of 5400、390 and 21.9 ?A mM-1 cm-2, respectively. The detecting limit was found to be 0.05 mM. Based on the Nafion?/urease/OMC/PANI-Nafion?/Au/Al2O3 as the sensing electrode the concentration of urea could be measured by monitoring the level of ammonium ion formed in the enzymatic reaction of urea. The maximum net cathodic peak current was obtained to be 417 μA in pH 6.88 phosphate buffer solution(PBS) when the loading of urease and sensing temperature were fixed at 2.12 U and 25 ℃, respectively. The maximum sensitivity of the urea biosensor was obtained to be 3595 ?A mM-1 cm-2 with the sensing limit of 0.005 mM Using Nafion?/urease(2.12 U)/OMC/PANI-Nafion?/Au/Al2O3 as the sensing electrode for the 5 ppm of Hg2+,it was found that the enzymatic activity was diminished about 58%. The sensitivity and the sensing limit to detect Hg2+ based on the same electrodes were obtained to be 5400 ?A ppm-1 cm-2 and 0.005 ppm for the concentration of Hg2+ in the ranges of 0.01?0.1 ppm. OMC was also treated with acid to improve the hydrophilism by increasing carboxyl group using sulfuric acid/nitric acid mixture of volume ratio of 3 to 1. The surface area of OMC decreased from 853 to 431 m2g-1 by increasing the time of acid treatment from 0 to 60 min. The pore structure was destroyed by acid treatment in low pressure, especially. The storage efficiency was found to be the best for the Nafion?/urease(2.12U)/OMC/PANI-Nafion?/Au/Al2O3 biosensor prepared by immobilizing urease using impregnation casting in low pressure ,and OMC treated with acid for 15 mins.
