Department of Chemistry, Durban University of Technology, P.O Box 1334, Durban 4000, South Africa.
Department of Chemistry, Durban University of Technology, P.O Box 1334, Durban 4000, South Africa; Department of Chemistry, Mangosuthu University of Technology, P.O. Box 12363, Jacobs 4026, South Africa.
Biosens Bioelectron. 2016 Sep 15;83:45-53. doi: 10.1016/j.bios.2016.04.037. Epub 2016 Apr 14.
The present study involves the development of a sensitive electrochemical biosensor for the determination of capsaicin extracted from chilli fruits, based on a novel signal amplification strategy using enzyme technology. For the first time, platinum electrode modified with multiwalled carbon nanotubes where phenylalanine ammonia-lyase enzyme was immobilized using nafion was characterized by attenuated total reflectance infrared spectroscopy, transmittance electron microscopy and thermo-gravimetric analysis supported by computational methods. Cyclic and differential pulse voltammetry measurements were performed to better understand the redox mechanism of capsaicin. The performance of the developed electrochemical biosensor was tested using spiked samples with recoveries ranging from 98.9 to 99.6%. The comparison of the results obtained from bare and modified platinum electrodes revealed the sensitivity of the developed biosensor, having a detection limit (S/N=3) of 0.1863µgmL(-1) and electron transfer rate constant (ks) of 3.02s(-1). Furthermore, adsorption and ligand-enzyme docking studies were carried out to better understand the redox mechanisms supported by density functional theory calculations. These results revealed that capsaicin forms hydrogen bonds with GLU355, GLU541, GLU586, ARG and other amino acids of the hydrophobic channel of the binding sites thereby facilitating the redox reaction for the detection of capsaicin.
本研究基于酶技术的新型信号放大策略，开发了一种用于测定从辣椒果实中提取的辣椒素的敏感电化学生物传感器。首次采用纳滤固定在多壁碳纳米管修饰的铂电极上的苯丙氨酸解氨酶酶，通过衰减全反射红外光谱、透射电子显微镜和热重分析以及计算方法进行了表征。进行了循环伏安和差分脉冲伏安测量，以更好地理解辣椒素的氧化还原机制。使用加标样品测试了所开发的电化学生物传感器的性能，回收率范围为 98.9%至 99.6%。裸铂电极和修饰铂电极的结果比较表明了所开发的生物传感器的灵敏度，其检测限（S/N=3）为 0.1863µgmL(-1)，电子转移速率常数（ks）为 3.02s(-1)。此外，还进行了吸附和配体-酶对接研究，以更好地理解密度泛函理论计算支持的氧化还原机制。这些结果表明，辣椒素与 GLU355、GLU541、GLU586、ARG 和结合位点疏水性通道中的其他氨基酸形成氢键，从而促进了检测辣椒素的氧化还原反应。
