Study and Fabrication on Solid State Enzyme Biosensors Based on Ammonium Ion-Selective Electrodes

• Main Authors: Nien-Hsuan Chou, 鄒年烜
• Other Authors: Shen-Kan Hsiung
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/08771332430971114119

碩士 === 中原大學 === 電子工程研究所 === 92 === The detection and determination of urea are the important parameters and great interests in biomedical and clinical analysis applications where a reduced level in urine and an increased concentration in blood are the important indication for renal dysfunction. Although there are direct spectrophotometric methods of urea determination, enzymatic methods are more selective and much more widely used. A potentiometric solid-state urea biosensor prepared by immobilization of urease directly onto the surface of an ammonium ion-selective electrode is described in this paper. The substrate of the ammonium ion-selective electrode is the tin oxide (SnO2) / indium tin oxide (ITO) glass and the enzyme was immobilized by entrapment method on a nonactin membrane incorporated carboxylated polyvinylchloride (PVC-COOH). However, for the quantitative expression for their selectivity is desired, the article employed the selectivity coefficients approach to estimate the selectivity of urea biosensors. In this study, experimental procedures based on the Nicolsky-Eisenman equation were considered. Therefore, the level of influence of the preference of the urea biosensors on the primary ions relative to interfering ions of is determined. According to this paper, urea biosensors based on ammonium ion-selective electrodes respond rapidly and stable within the pH range from pH 6 to pH 7.5. The slope in the linear range (0.026 mM to10 mM) is about 55.56±3.15 mV/decade and the detection limit is 5 μM. Moreover, the use of ammonium ion-selective electrode has the advantage of providing solid-state urea biosensors that are easy to fabricate, good reproducibility and stability, low cost and allow miniaturization configuration.