Spectrophotometric and amperometric biosensors based on conducting polymers of 1-benzyl-2,5-di(thiophen-2-yl)- 1H-pyrrole and(4,7-dithien-2-yl-2,1,3-benzothiadiazole)

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Kimya Bölümü, Türkiye

Tezin Onay Tarihi: 2012

Öğrenci: SİMLA TANRIVERDİ

Danışman: LEVENT KAMİL TOPPARE

Özet:

In this thesis, two different biosensors based on conducting polymers of (4,7-dithien-2-yl-2,1,3-benzothiadiazole) (TBTD) and 1-benzyl-2,5 di(thiophene-2-yl)-1H-Pyrrole (SNBS) were prepared. Electrochemical technique was used for polymerization of conducting polymers and two different immobilization techniques were used for immobilizing enzyme into the conducting polymer matrices. The proposed biosensors were characterized and optimized. Optimum pH, thickness, enzyme amount were determined and linearity, repeatability, operational stability experiments were performed. In the first part of the thesis a redox enzyme alcohol oxidase was immobilized in TBTD/EDOT bilayer and PEDOT to construct an amperometric biosensor. AOX is responsible for the oxidation of low molecular weight alcohols to the corresponding aldehyde, using molecular oxygen as the electron acceptor. Using entrapment method, alcohol oxidase enzyme was immobilized in PEDOT matrix on platinum disk electrodes. Then, enzyme was immobilized in poly(4,7-dithien-2-yl-2,1,3-benzothiadiazole) (TBTD)-EDOT matrix. Finally these two were compared. Proposed biosensors were characterized using ethanol as the substrate and the responses were measured. Kinetic parameters, Imax, Km and sensitivity were determined for the biosensors with and without TBTD. Optimization studies for TBTD thickness, PEDOT amount and pH were carried out. The biosensing capacity was discussed for TBTD matrix. In the second part of the thesis a second biosensor was designed through electrochemical polymerization of 1- benzyl-2,5 di(thiophene-2-yl)-1H-Pyrrole (SNBS). Invertase enzyme immobilized SNBS generates a spectrophotometric biosensor. Kinetic parameters, Michaelis- Menten constant, Km, maximum reaction rate, Vmax were investigated. Operational stability, pH and temperature optimization of the enzyme electrodes were also examined.