Electrochemistry Research Group, Department of Chemistry, St. Joseph's College, Lalbagh Road, Bangalore, 560027, Karnataka, India.
Electrochemistry Research Group, Department of Chemistry, St. Joseph's College, Lalbagh Road, Bangalore, 560027, Karnataka, India.
Mater Sci Eng C Mater Biol Appl. 2017 Apr 1;73:552-561. doi: 10.1016/j.msec.2016.12.114. Epub 2016 Dec 24.
Free radicals are formed as byproducts of metabolism, and are highly unstable due to the presence of unpaired electrons. They readily react with other important cellular components such as DNA causing them damage. Antioxidants such as (+)-catechin (CAT), neutralize free radicals in the blood stream. Hence there is a need for detection and quantification of catechin concentration in various food sources and beverages. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A carbon paste working electrode modified by electropolymerizing methylene blue (MB) was fabricated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) techniques were used to study the surface morphology of the electrode. Quasi-reversible electron transfer reaction occurred at +0.260V through a diffusion controlled process. In comparison to the bare carbon paste electrode (CPE), there was a significant 5.3 times increment in anodic current sensitivity at the modified electrode at physiological pH. Our findings indicate that for the electro-oxidation of CAT, CPE is a better base material for electropolymerization of MB compared to glassy carbon electrode (GCE). Nyquist plot followed the theoretical shape, indicating low interfacial charge transfer resistance of 0.095kΩ at the modified electrode. Calibration plots obtained by DPV were linear in two ranges of 1.0×10 to 1.0×10 and 1.0×10 to 0.1×10M. The limit of detection (LOD) and limit of quantification (LOQ) was 4.9nM and 14nM respectively. Application of the developed electrode was demonstrated by detecting catechin in green tea and spiked fruit juice with satisfactory recoveries. The sensor was stable, sensitive, selective and reproducible.
自由基是新陈代谢的副产物，由于存在不成对的电子，它们非常不稳定。它们容易与其他重要的细胞成分（如 DNA）发生反应，导致它们受损。抗氧化剂如（+）-儿茶素（CAT）可以在血液中中和自由基。因此，需要检测和定量各种食物来源和饮料中的儿茶素浓度。使用循环伏安法（CV）和差分脉冲伏安法（DPV）研究了儿茶素的电氧化性质。通过电聚合亚甲蓝（MB）制备了修饰的碳糊工作电极。场发射扫描电子显微镜（FESEM）和原子力显微镜（AFM）技术用于研究电极的表面形态。通过扩散控制过程，在+0.260V 处发生准可逆电子转移反应。与裸碳糊电极（CPE）相比，在生理 pH 值下，修饰电极的阳极电流灵敏度显著增加了 5.3 倍。我们的研究结果表明，对于 CAT 的电氧化，CPE 是比玻碳电极（GCE）更好的电聚合 MB 的基底材料。奈奎斯特图遵循理论形状，表明在修饰电极处的界面电荷转移电阻低至 0.095kΩ。通过 DPV 获得的校准曲线在两个范围 1.0×10 到 1.0×10 和 1.0×10 到 0.1×10M 内呈线性。检测限（LOD）和定量限（LOQ）分别为 4.9nM 和 14nM。通过检测绿茶和加标果汁中的儿茶素，展示了开发的电极的应用，回收率令人满意。该传感器具有稳定性、灵敏度、选择性和重现性。
