Investigation of the usability of modified and unmodified disposable graphite electrodes as DNA hybridization sensor

In this thesis, 5-amino-1,3,4-thiadiazole-2-thiol (AMT) was covered onto the disposable pencil graphite electrode as a thin film by electropolymerization and this surface of the modified electrode (poly-AMT-PGE) was used for the detection of DNA hybridization. AMT was polymerized onto the electrode surface by using cyclic voltammetry technique for the full coverage of the electrode surface by poly-AMT. By using polymer modified electrode it was aimed to detect DNA hybridization with low detection limit, high selectivity and repeatability. The surface and electrochemical characterization of poly-AMT modified PGE (p-AMT-PGE) was performed by using scanning electron microscopy and electrochemical impedans spectroscopy. Bare-PGE and p-AMT-PGE were compared in terms of DNA probe immobilization and DNA hybridization was carried out onto the surface of p-AMT-PGE. The selectivity of the prepared electrode was tested by target DNA (complementary), one base mismatch (MM) and noncomplementary (NC) DNA sequences and the detection limit was determined. Keywords: 5-amino-1,3,4-thiadiazole-2-thiol, pencil graphite electrode, gold nanoparticle, electrochemical biosensor.