Reduced-Graphene-Oxide/ Gold-Nanoparticles Modified Glassy-Carbon-Electrode for the Detection of Adrenaline

Abstract

Our motivation for this work is to extend the undiscovered properties of Reduced-Graphene-Oxide/ Gold-Nanoparticles (rGO/AuNPs) sensor, optimizing sensor structure, and conditions for the future use of portable adrenaline detection sensors. Optimizing all of the conditions and parameters gives us a better perspective of the overall process, especially when designing future electrodeposition coatings or a new type of sensor. Electrochemistry has been widely used in industry due to its low cost and efficiency in mass production. Some electrochemistry sensors are paired with microprocessors to increase their portability, making them easier to use and analyze. Literature reviews of the recent five years of published papers based on adrenaline detection are compared in Chapter 1. Multiple sensors include different materials, different designs, different methods of detection are compared for a better understanding of electrochemistry sensors. Then in Chapter 2, our goal is to test the performance of this electrochemically modified rGO/Au-NPs/GCE electrode under an acidic environment. As a method to analyze the surface structure of the electrode, we have chosen Scanning Electron Microscope (SEM) image and EDS spectrum to prove that gold nanoparticles and Graphene sheets are decorated on the surface of the glassy carbon electrode (GCE). We reported the optimization process of the electrodeposition procedure, break-in surface treatment study, DPV parameters optimization, adrenaline signal calibration, and interference study at selected pH. Repeatability and stability were also evaluated from the experiment results since they represented an important role in determining the long-term applicability of these electrochemically modified electrodes. The electrodes showed excellent repeatability, indicating that electrodeposited electrodes have similar scan results in adrenaline current detection. The standard deviation error between the ten electrodes tested in the stability test is 4.95%. Furthermore, we provided a set of analyzed data for GO/HAuCl4 Electrodeposition material and adrenaline detection performance based on the DPV study. Finally, the detection limit in pH 5.5 SAB buffer was measured and calculated to be 0.4 uM, the detection limit in artificial urine is 1.16 uM, and the linear adrenaline detection range in pH 5.5 SAB buffer is from 0.3 uM to 200 uM. The electrodes were electrochemically stable with the stability test and calibration results and can be modified for future analysis of AD in buffer and artificial biosamples. Finally, in chapter 3 we discussed rGO/AuNPs/GCE electrode’s future developments and applications.