Functionalization and fabrication of polymer based device platform architectures for sensor applications

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2018

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Söylemez, Saniye

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In this thesis, two types of sensors: Conjugated polymer based amperometric biosensors and a chemiresistive sensor (polymer/SWCNT) for clinical and food applications were designed, fabricated and characterized. Three chapters in this thesis focused on ethanol, glucose and cholesterol biosensors based on functional polymer/MWCNT composition, different peptide sequence containing polymer, and also copolymer of two different functional monomers, respectively. After successful electrochemical deposition of the polymers on the graphite electrode surfaces, immobilization of alcohol oxidase (AOx), glucose oxidase (GOx) and cholesterol oxidase (ChOx) were carried out. Since conjugated polymer based biosensors are recognized to be a next generation building architecture for highly sensitive and fast biosensing systems, in this thesis, it is aimed to create new biosensor systems for the quantitative detection of ethanol, glucose and cholesterol which are thought to play an important role to prevent several diseases. To construct a chemiresistive sensor, nanowires (NWs), especially carbon nanotubes (CNTs), as the basis for chemiresistor research were used. In this work, single walled carbon nanotubes (SWCNTs) due to their excellent conductivity, exceptional aspect ratios, and numerous methods available for functionalization were favored. The first step generates a surface wherein P4VP-SWCNT dispersion was spray-coated and covalently linked to the surface. The P4VP dispersant not only displays a favorable interaction with SWCNTs to stabilize debundled dispersion, but it also allows further modifications on its nucleophilic pyridyl nitrogens with alkyl halides. In the second step, a post-functionalization of P4VP-SWCNT surface via reacting with 2- bromoethanol was implemented. Finally, GOx was immobilized on the modified surface to detect glucose in beverages. As a conclusion, all devices constructed in this thesis present four new examples in biosensing applications that overcome challenges associated with analysis time, selectivity and also requirement of pretreatment of the samples. Sensor performances were also evaluated for each sensor. Additionally, surface features of the sensors and molecules were fully characterized using NMR, SEM, XPS, CV, FT-IR and Raman techniques depending on the type of sensor. To further test the sensing performance, the sensors were tested towards their specific analytes and showed promising feasibility for the quantitative analysis in beverages and human blood samples.

Subject Keywords

Ethanol., Glucose., Biosensors., Electrochemistry., Conjugated polymers., Conductometric analysis.

URI

http://etd.lib.metu.edu.tr/upload/12621786/index.pdf
https://hdl.handle.net/11511/27014

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

S. Söylemez, “Functionalization and fabrication of polymer based device platform architectures for sensor applications,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.