Ali Md Azahar, Singh Nawab, Srivastava Saurabh, Agrawal Ved V, John Renu, Onoda M, Malhotra Bansi D
Department of Science and Technology Centre on Biomolecular Electronics, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi, 110012, India.
Appl Biochem Biotechnol. 2014 Oct;174(3):926-35. doi: 10.1007/s12010-014-1179-5. Epub 2014 Sep 9.
We have fabricated an immunosensor based on carbon nanotubes and chitosan (CNT-CH) composite for detection of low density lipoprotein (LDL) molecules via electrochemical impedance technique. The CNT-CH composite deposited on indium tin oxide (ITO)-coated glass electrode has been used to covalently interact with anti-apolipoprotein B (antibody: AAB) via a co-entrapment method. The biofunctionalization of AAB on carboxylated CNT-CH surface has been confirmed by Fourier transform infrared spectroscopic and electron microscopic studies. The covalent functionalization of antibody on transducer surface reveals higher stability and reproducibility of the fabricated immunosensor. Electrochemical properties of the AAB/CNT-CH/ITO electrode have been investigated using cyclic voltammetric and impedimetric techniques. The impedimetric response of the AAB/CNT-CH/ITO immunoelectrode shows a high sensitivity of 0.953 Ω/(mg/dL)/cm(2) in a detection range of 0-120 mg/dL and low detection limit of 12.5 mg/dL with a regression coefficient of 0.996. The observed low value of association constant (0.34 M(-1)s(-1)) indicates high affinity of AAB/CNT-CH/ITO immunoelectrode towards LDL molecules. This fabricated immunosensor allows quantitative estimation of LDL concentration with distinguishable variation in the impedance signal.
我们基于碳纳米管和壳聚糖（CNT-CH）复合材料制备了一种免疫传感器，用于通过电化学阻抗技术检测低密度脂蛋白（LDL）分子。沉积在氧化铟锡（ITO）涂层玻璃电极上的CNT-CH复合材料已通过共包埋法与抗载脂蛋白B（抗体：AAB）共价相互作用。通过傅里叶变换红外光谱和电子显微镜研究证实了AAB在羧基化CNT-CH表面的生物功能化。抗体在换能器表面的共价功能化表明所制备的免疫传感器具有更高的稳定性和重现性。使用循环伏安法和阻抗法研究了AAB/CNT-CH/ITO电极的电化学性质。AAB/CNT-CH/ITO免疫电极的阻抗响应在0-120mg/dL的检测范围内显示出0.953Ω/(mg/dL)/cm²的高灵敏度，检测下限为12.5mg/dL，回归系数为0.996。观察到的低缔合常数（0.34M⁻¹s⁻¹）表明AAB/CNT-CH/ITO免疫电极对LDL分子具有高亲和力。这种制备的免疫传感器允许通过阻抗信号的明显变化对LDL浓度进行定量估计。
