Development of a new ethanol biosensor based on polyfluorene- g- poly(ethyleneglycol) and multiwalled carbon nanotubes

Deniz, Sıddıka Aybüke
In this thesis study, a novel amperometric biosensor containing a conjugated polymer and a multiwalled carbon nanotube was developed for ethanol detection. Conjugated polymers have gained interest in biosensing and biomedical applications recently. Their ability to increase the effective surface area and adjustable surface morphology make them convenient candidates for suitable enzyme immobilization. The conjugated polymer poly(ethylene glycol) is soluble in both water and organic solvents. Besides, it interacts with the enzymes readily due to its hydrophilic nature. In this thesis, poly(ethylene glycol) with fluorene functionality was synthesized via a one-step procedure. The construction of biosensor was achieved through the modification of graphite electrode with synthesized conjugated polymer in addition to carbon nanotubes. Carbon nanotubes were used as supporting materials due to their fast electron transfer and electrochemical stability. Surface characterization and electrochemical characterization of the biosensor was performed using scanning electron microscopy and cyclic voltammetry, respectively. Combination of conjugated polymer and multiwalled carbon nanotubes improved the performance of biosensor and showed high sensing ability compare to similar control biosensor (without PF-g-PEG or MWCNT). Alcohol oxidase enzyme (AOx) was immobilized on the modified electrode surface and several parameters effecting the performance of modified biosensor were optimized. The optimized biosensor exhibited good analytical parameterssuch as low limit of detection and high sensitivity. Linear range of proposed biosensor was between 0.0085-5.95 mM with detection limit of 0.11 mM and sensitivity value of 7.99 µAmM-1 cm-2 . Finally, to show the applicability of proposed biosensor, the biosensor was tested for different alcoholic beverages for ethanol analysis.
Citation Formats
S. A. Deniz, “Development of a new ethanol biosensor based on polyfluorene- g- poly(ethyleneglycol) and multiwalled carbon nanotubes,” M.S. - Master of Science, Middle East Technical University, 2021.