Abstract
In this study, simultaneous electrochemical detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) was performed using a modified graphite paste electrode (MGPE) with epigallocatechin gallate (EGCG) and green tea (GT) powder. It was shown that the anodic peak current increased in comparison with that of the graphite paste electrode (GPE) in the cyclic voltammograms. The optimal pH for simultaneous determination of a quaternary mixture of AA–DA–UA was determined to be pH 2. The anodic peak potentials for a mixture containing AA–DA–UA were well separated from each other. The catalytic peak currents obtained at the surface of the MGPE/EGCG were linearly dependent on the AA, DA, and UA concentrations up to 23, 14, and 14 µM, respectively. The detection limits for AA, DA, and UA were 190, 90, and 70 nM, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of AA, DA, and UA in real samples. Finally, a modified electrode was prepared using GT and used for simultaneous determination of AA, DA, and UA. Based on the results, MPGE/GT showed two oxidation peaks at 0.43 and 0.6 V for DA and UA, respectively, without any oxidation peak for AA. The calibration curves at the surface of MGPE/GT were linear up to 14 µM with a detection limit of 0.18 and 0.33 µM for DA and UA, respectively. MGPEs provide a promising platform for the future development of sensors for multiplexed electrochemical detection of clinically important analytes.
Highlights
Tea is one of the most widely consumed beverages in the world, with the main varieties being green and black
We have developed an epigallocatechin gallate (EGCG) modified graphite paste electrode (MGPE) for the simultaneous electrochemical detection of analytes such as ascorbic acid (AA), dopamine (DA), and uric acid (UA), using differential pulse voltammetry (DPV)
The results show that the peak currents are linearly proportional to the concentration of AA, while those of the other three analytes did not change; this indicates that the oxidation of AA, DA, and UA at MGPE/EGCG takes place independently
Summary
Tea is one of the most widely consumed beverages in the world, with the main varieties being green and black. The major catechins found in green tea are catechin (C), (−)-epicatechin (EC), (−)-epicatechin 3-gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin gallate (EGCG) [2]. EGCG, in particular, has been shown to have interesting properties including many potential therapeutic benefits such as anti-inflammatory [3,4], anti-cancer [5,6], and anti-steatotic [7] effects. Research from our lab has shown that EGCG interacts with key proteins implicated in Alzheimer’s disease (AD), such as amyloid-β [8], and prevents aggregation of amyloid-β in the presence of metals such as copper [9]. EGCG has Sensors 2018, 18, 23; doi:10.3390/s18010023 www.mdpi.com/journal/sensors
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
