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Bioanalytical applications of boron doped diamond electrodes
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Rajan, Teena Susan (2022) Bioanalytical applications of boron doped diamond electrodes. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3970578
Abstract
Maintaining pH homeostasis is one of the most important biological processes, and variations in tissue or fluid pH can often be related to diseases. Hence, detecting pH changes accurately could be crucial for early diagnosis. This thesis investigates electrochemical methods for accurate biological pH measurements. Of importance is characterising protein fouling on the electrode surfaces and the implications for accurate pH evaluation.
Chapter 3 investigates the ex vivo pH profiling of the gastrointestinal (GI) tract using an electrochemical pH sensor. Also, the variation caused by omeprazole and melatonin, known to alter the pH in upper GI tract. Three pH electrodes, glass electrode, iridium oxide electrodeposited on boron doped diamond (BDD-IrOx), and quinone surface integrated BDD (BDD-Q), were assessed in a GI-tract mimic solution to determine suitability before ex vivo application. When assessing the electrodes in terms of response time, robustness and minimal electrode fouling, the BDD-Q was determined to be the most suitable sensor.
Chapter 4 explores the effect of protein adsorption on: BDD, a BDD that has the whole surface laser ablated to sp2 carbon (sp2-BDD), and a glassy carbon. The performance of these electrodes was assessed in 0.5% mucin (GI-tract mimic), and 5% bovine serum albumin (most abundant protein in blood). Fouling was studied using three different methods: (i) Time-dependent change in cyclic voltammograms of metal redox couples (Ru(NH3)63+, IrCl62-); (ii) Changes in double layer capacitance in response to protein solutions; and (iii) the effect of applied electrode potential on protein adsorption and the subsequent silver electrodeposition.
Chapter 5 describes the development of a 3D-printed flow cell capable of housing a BDD-Q pH electrode to conduct pH measurements under controlled flow. We hypothesise that flow can be used to reduce fouling from mucin and albumin. The BDD-Q sensor was flow-independent in the range from 0.1 to 100 mL/min. The pH of solutions containing proteins were measured under stationary and flow (100 mL/min) conditions, while alternating with buffer solution. Conducting pH measurements under flow improved the accuracy of the measurement. A similar experiment was conducted in blood, a more complex media with multiple proteins. Measurements conducted at 100 mL/min showed low variation in pH using the BDD-Q.
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QD Chemistry R Medicine > RC Internal medicine T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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Library of Congress Subject Headings (LCSH): | Acid-base imbalances, Electrochemistry, Diamonds -- Electric properties, Boron -- Electric properties, Acid-base imbalances -- Detection, Protein -- Absorption, Electrodes, Glass, Coated electrodes | ||||
Official Date: | December 2022 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Chemistry | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Macpherson, Julie V. | ||||
Sponsors: | University of Warwick. Department of Chemistry ; Engineering and Physical Sciences Research Council ; University of Warwick. Diamond Science Technology Centre | ||||
Format of File: | |||||
Extent: | xx, 170 pages : illustrations | ||||
Language: | eng |
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