Development of amperometric cholinesterase biosensors based on a conducting polymer for detection of anti-dementia drugs and pesticides

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Tezin Türü: Yüksek Lisans

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

Tezin Onay Tarihi: 2016

Öğrenci: JANSET TURAN

Danışman: LEVENT KAMİL TOPPARE

Özet:

Cholinesterase enzymes are considered as one of the most important enzymes in living organisms and they are targeted by many inhibitors. Cholinesterase inhibitors are potentially toxic however they also have certain applications as treatment of dementia and Alzheimer’s diseases. These inhibitors can bind the active side of the cholinesterase enzymes forming stable complexes. This inhibitory effect can be used to construct fast and sensitive detection system. Also, conducting polymers are known to be well suited immobilization platforms in biosensor construction since they can easily be coated on the surface homogenously and, can offer stability and biocompatibility to the sensing system. Aim of this thesis is to develop amperometric biosensors based on a conducting polymer for detection of the several anti-dementia drugs and pesticides. For this purpose different sensor platforms were successfully modified with excellent surface designs by either creating the conducting copolymer structure on the surface or introducing silver nanowire to the sensor. Conducting polymers; poly(5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]oxadiazole) Poly(BODT)) and poly(5,6-bis(octyloxy)-4,7-di(thieno[3][3,2-b]thiophen-2-yl)benzo[c][1,2,5]oxoadiazole) Poly(TTBO)) were utilized as immobilization platforms. Following the electrochemical deposition, Cholinesterase enzymes; Acetylcholinesterase (AChE) or butyrylcholinesterase (BChE) was immobilized on polymer coated graphite electrodes. The optimized biosensors showed a very good linearity with rapid response times and low detection limits (LOD) to acetylcholine and butyryl thiocholine iodide substrates. Surface modifications and electrochemical characteristics of the sensing systems were characterized via SEM and CV techniques respectively. Under optimal operational parameters, designed biosensor systems were tested for the detection of pharmaceuticals and pesticides in different media.