Barik Md Abdul, Sarma Manoj Kumar, Sarkar C R, Dutta Jiten Ch
Department of Electronics and Communication Engineering, Tezpur University, Tezpur, Assam, 784028, India,
Appl Biochem Biotechnol. 2014 Oct;174(3):1104-14. doi: 10.1007/s12010-014-1029-5. Epub 2014 Jul 9.
Highly sensitive potassium (K)-doped carbon nanotube (CNT) and polypyrrole (PPy) nanocomposite membrane-based enzyme field effect transistor (ENFET) has been fabricated on indium tin oxide (ITO) for detection of cholesterol. P-type graphene has been deposited as substrate on ITO glass electrochemically. N-type graphene has been deposited in source and drain regions. Zirconium dioxide (ZrO2) has been deposited on the channel region as gate insulator. K/PPy/CNT composite has been deposited as sensing membrane on the top of ZrO2 layer; 1 μl of cholesterol oxidase (ChOx) has been immobilized on K/PPy/CNT membrane via physical adsorption technique. The response of K/PPy/CNT/FET has been studied using Agilent 3458A digital multimeter in presence of phosphate buffer saline (PBS) of 50 mM, pH 7.0 and 0.9 % NaCl contained in a glass pot. During measurement, 20 μl cholesterol solutions (0.5 to 25 mM) were poured into the pot through micropipette each time. It has been found that K/PPy/CNT/FET has linearly varied from 0.5 to 20 mM. The sensitivity of this FET has been found to be ~400 μA/mM/mm(2) with regression coefficient (r) ~ 0.998. The proposed ENFET has response time of 1 s and stability up to 6 months. The experiment has been repeated 10 times, and only 2.0 % output variation has been observed. The limit of detection (LoD) and Michaelis-Menten constant (K m) were found to be ~1.4 and 2.5 mM, respectively. The results obtained in this work show negligible interference (3.7 %) with uric acid, glucose and urea.
基于高灵敏度钾（K）掺杂碳纳米管（CNT）和聚吡咯（PPy）纳米复合膜的酶场效应晶体管（ENFET）已制备在氧化铟锡（ITO）上用于检测胆固醇。P型石墨烯已通过电化学方法沉积在ITO玻璃上作为基底。N型石墨烯已沉积在源极和漏极区域。二氧化锆（ZrO2）已沉积在沟道区域作为栅极绝缘体。K/PPy/CNT复合材料已作为传感膜沉积在ZrO2层顶部；1μl胆固醇氧化酶（ChOx）已通过物理吸附技术固定在K/PPy/CNT膜上。在含有50mM、pH 7.0的磷酸盐缓冲盐水（PBS）和0.9% NaCl的玻璃罐中，使用安捷伦3458A数字万用表研究了K/PPy/CNT/FET的响应。在测量过程中，每次通过微量移液器将20μl胆固醇溶液（0.5至25mM）倒入罐中。已发现K/PPy/CNT/FET在0.5至20mM范围内呈线性变化。已发现该FET的灵敏度约为400μA/mM/mm²，回归系数（r）约为0.998。所提出的ENFET的响应时间为1秒，稳定性高达6个月。该实验已重复10次，仅观察到2.0%的输出变化。检测限（LoD）和米氏常数（Km）分别约为1.4和2.5mM。这项工作中获得的结果表明，对尿酸、葡萄糖和尿素的干扰可忽略不计（3.7%）。
