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Developing a Stable and Selective Non-Enzymatic Electrochemical Glucose Biosensor

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Developing a Stable and Selective Non-Enzymatic Electrochemical Glucose Biosensor Developing a Stable and Selective Non-Enzymatic Electrochemical Glucose Biosensor A Major Qualifying Project Submitted to the Faculty of Worcester Polytechnic Institute In partial fulfillment of the requirements for the Degree in Bachelor of Science In Chemical Engineering By: Zihao Li Randy Melanson Date: 04/21/2018 Project Advisor Professor Hong Susan Zhou This report represents work of WPI undergraduate students submitted to the faculty as evidence of a degree requirement. WPI routinely publishes these reports on its web site without editorial or peer review. For more information about the projects program at WPI, see http://www.wpi.edu/Academics/Projects. Abstract The goal of this Major Qualifying Project was to develop a stable and sensitive interface architecture for an easy and reusable non-enzymatic electrochemical glucose biosensor. This was achieved by changing the copper oxide nanoparticle morphology that was deposited onto a titanium oxide nanotube array. The interface architecture of the electrode was manipulated by varying the concentration of the equimolar CuSO4/H2SO4 solution from 7.8 mM to 250 mM during electrodeposition. Through SEM imaging, cyclic voltammetry scans, and chronoamperometric readings, it was determined that the biosensor interface architecture affected its overall glucose sensing capabilities. The most ideal interface architecture that resulted in the best performing electrochemical glucose biosensor was produced in an electrolyte solution of 50 mM CuSO4/H2SO4. At this concentration, the biosensor had a linear glucose sensitivity range from 0.2 to 1.0 mM glucose and had a correlation coefficient of 0.964. 1 Acknowledgements This project team would like to thank our advisor, Professor Hong Susan Zhou, for her guidance and support through the completion of this project. Additionally, this team would like to thank the doctoral candidate, Zhiru Zhou, for her assistance and collaboration especially with the SEM imaging. 2 Table of Contents Abstract ...................................................................................................................................... 1 Acknowledgements ..................................................................................................................... 2 Table of Contents ........................................................................................................................ 3 Table of Figures .......................................................................................................................... 5 Chapter 1: Introduction ............................................................................................................... 8 1.1 Electrochemical Glucose Biosensors 8 1.2 Elements of an Electrochemical Glucose Biosensor 9 Chapter 2: Non-enzymatic Interface Architecture ...................................................................... 11 2.1 Chemical Stability and Biocompatibility of Titanium Metal 11 2.2 Selective Detection with High Surface Area Titania Nanostructures 12 2.3 Self-Cleaning Applications of Titania for Biosensing 15 2.4 Combining Catalytic Potential of Copper Oxide with Titanium Nanotube Array 15 Chapter 3: Experimental Theory................................................................................................ 18 3.1 Titanium Pretreatment 18 3.1.1 Polishing................................................................................................................... 18 3.1.2 Solvent cleaning ....................................................................................................... 18 3.1.3 Pickling .................................................................................................................... 18 3.2 Electrochemical Techniques 19 3.2.1 Anodic Oxidation ..................................................................................................... 19 3.2.2 Three-electrode Setup ............................................................................................... 20 3.2.3 Chronoamperometry ................................................................................................. 21 3.2.4 Cyclic Voltammetry.................................................................................................. 22 3.3 Analytical Techniques 23 3.3.1 Scanning Electron Microscopy ................................................................................. 23 3.3.2 X-ray Diffraction ...................................................................................................... 23 3 Chapter 4: Experimental Setup .................................................................................................. 24 4.1 Preparation of TiO2 Nanotube Array 24 4.2 Preparation of the CuO/TNT Heterostructure 24 4.3 Measurements 24 Chapter 5: Results and Discussion ............................................................................................. 25 5.1 Synthesizing CuO/TNT Heterostructure by Varying Electrolyte Concentration 25 5.2 Investigating a Broad Electrolyte Concentration Range on Electrode Morphology 27 5.3 Investigating a Broad Electrolyte Concentration Range on Electrode Function 29 5.4 Investigating a Narrow CuSO4/H2SO4 Concentration Range on Electrode Function 33 5.5 UV Irradiation Improves Electrode Function 36 5.6 Electrochemical Deposition Techniques Affect Nanoparticle Morphology 38 Chapter 6: Conclusion and Recommendation ............................................................................ 39 References ................................................................................................................................ 40 Appendix A: Cyclic Voltammograms for Electrodes Synthesized Under Broad Electrolyte Concentration Range ................................................................................................................. 43 Appendix B: Cyclic Voltammograms for Electrodes Synthesized Under Narrow Electrolyte Concentration Range ................................................................................................................. 47 4 Table of Figures Figure 1: Elements of a biosensor ................................................................................................ 9 Figure 2: Anodization process of titanium metal in electrolyte solution. .................................... 12 Figure 3: Sequence of a catalytic reaction.................................................................................. 13 Figure 4: Formation of titanium nanotubes under anodic oxidation in an electrolyte solution containing fluorine. ................................................................................................................... 14 Figure 5: Copper oxide decorated titanium nanotube heterostructure. ........................................ 16 Figure 6: SEM images of Cu2O particles (a) cubes; (b) Truncated octahedral; (c) Octahedral; and (d) Hexapods with scale bar: 1um. ............................................................................................ 17 Figure 7: Experimental setup for anodic oxidation..................................................................... 19 Figure 8: Experimental setup depicting three-electrode cell. ...................................................... 20 Figure 9: Applied waveform for chronoamperometry. ............................................................... 21 Figure 10: Typical voltammogram for chronoamperometry. ...................................................... 21 Figure 11: Applied waveform for cyclic voltammetry. .............................................................. 22 Figure 12: Typical voltammogram for a reversible reaction. ...................................................... 22 Figure 13: Sample SEM image of titanium nanotube array. ....................................................... 23 Figure 14: Titanium foils after anodic oxidation. ....................................................................... 25 Figure 15: Oxidized layers formed on the foils after annealing. ................................................. 26 Figure 16: Copper deposition seen on the titanium foil after chronoamperometry. ..................... 26 Figure 17: Successive CuSO4 dilutions during chronoamperometry from left to right and top to bottom highlighting color change. ............................................................................................. 27 Figure 18: SEM imaging of Cu2O/TNT heterostructures developed using chronoamperometry in an electrolyte solution of CuSO4 and H2SO4 at concentrations of (a) 7.8 mM; (b) 15.6 mM; (c) 31.2 mM; (d) 62.5 mM; (e) 125 mM; and (f) 250 mM. .............................................................. 28 Figure 19: SEM image of the 62.5 mM Cu2O/TNT heterostructure highlighting nanofibers and copper oxide nanoparticle cluster. ............................................................................................. 28 Figure 20: ImageJ measurements of the nanoparticle diameters as a function of the CuSO4/H2SO4 concentration. ........................................................................................................................... 29 5 Figure 21: Cyclic voltammogram for 15.6 mM electrode in 0.1 M NaOH + 2 mM glucose (blue) and in 0.1 M NaOH (red). Cyclic voltammogram for bare titanium nanotube array in 0.1 M NaOH + 2 mM glucose (green) and in 0.1 M NaOH (purple). .............................................................. 30 Figure 22: Cyclic voltammogram for 125 mM electrode in 0.1 M NaOH
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