Arora Kavita, Choudhary Meenakshi, Malhotra Bansi D
Advanced Instrumentation Research Facility, Jawaharlal Nehru University, New Delhi, 110067, India,
Appl Biochem Biotechnol. 2014 Oct;174(3):1174-87. doi: 10.1007/s12010-014-0996-x. Epub 2014 Jun 14.
Multiwalled carbon nanotubes (CNT) doped polyaniline (Pani) nanocomposite has been electrochemically deposited onto indium tin oxide (ITO)-coated glass substrate for fabrication of uric acid biosensor. To achieve this, uricase (from Bacillus fastidiosus) has been covalently immobilized onto glutaraldehyde-modified CNT-Pani/ITO and characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, electrochemical impedance spectroscopy (EIS), etc. CV studies of CNT-Pani/ITO electrode reveals that the system obeys quasi-reversible electron transfer behavior with diffusion coefficient of 2.3346 × 10(-8) cm s(-1) in K3FeCN6. Fabricated uricase-CNT-Pani/ITO electrodes were tested for uric acid detection in buffer and spiked serum samples electrochemically. It was found that fabricated electrode was able to detect 0.01-1.0 mM uric acid using CV and 0.02-0.8 mM uric acid using differential pulse voltammetry (DPV). The enhanced electrochemical performance of this biosensor is due to the high enzyme loading synergistically connected to CNT-Pani nanocomposite leading to improved enzyme characteristics such as Km value of 4.85 × 10(-3) mM L(-1) (about 70 times less than the free enzyme), sensitivity of 43.2 μA mM(-1) for CV-based detection and 8.38 μA mM(-1) for DPV-based detection within response time of 60 s. Fabricated electrodes were able to maintain their electrochemical activity with 60 times reusability and were stable up to 28 weeks when stored at 4 °C.
多壁碳纳米管（CNT）掺杂聚苯胺（Pani）纳米复合材料已通过电化学沉积在氧化铟锡（ITO）涂层玻璃基板上，用于制备尿酸生物传感器。为此，将尿酸酶（来自苛求芽孢杆菌）共价固定在戊二醛修饰的CNT-Pani/ITO上，并使用循环伏安法（CV）、扫描电子显微镜（SEM）、傅里叶变换红外（FTIR）光谱、电化学阻抗谱（EIS）等进行表征。CNT-Pani/ITO电极的CV研究表明，该系统在K3FeCN6中遵循准可逆电子转移行为，扩散系数为2.3346×10(-8) cm s(-1)。对制备的尿酸酶-CNT-Pani/ITO电极进行了电化学检测缓冲液和加标血清样品中尿酸的测试。结果发现，制备的电极使用CV能够检测0.01-1.0 mM尿酸，使用差分脉冲伏安法（DPV）能够检测0.02-0.8 mM尿酸。这种生物传感器电化学性能的提高归因于与CNT-Pani纳米复合材料协同连接的高酶负载量，从而改善了酶的特性，如Km值为4.85×10(-3) mM L(-1)（约为游离酶的70分之一），基于CV检测的灵敏度为43.2 μA mM(-1)，基于DPV检测的灵敏度为8.38 μA mM(-1)，响应时间为60秒。制备的电极能够保持其电化学活性，可重复使用60次，在4°C储存时长达28周稳定。
