چكيده به لاتين
Abstract
In the first part of this dissertation, an electrochemical sensor was designed and developed for the determination of Cysteine amino acid. A pencil graphite electrode (PCE) was modified with a Co(II)-Al(III) layered double hydroxide (LDH) to obtain a disposable, inexpensive and sensitive sensor for Cysteine. The LDH was electrochemically deposited by a chronoamperometric method by employing a 0.9V constant potential on the working electrode. The electrochemical behavior of the modified electrode was investigated using cyclic voltammetric method (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and linear scanning voltammetry (LSV). All tests in optimal conditions by the potential scan rate of 10 mVs-1 and at pH=13 was performed and the Cysteine oxidation peak was observed at about 0.15 V. A linear range of the concentration was obtained 0.1μM-100PM and the experimental detection limit was equal to 100PM. The proposed electrode was used to measure Cysteine in a pharmaceutical sample. This modified electrode is inexpensive and easily and fastly prepared.
In the next section, screening for Hepatitis B is one of the major health problems in the world and in Iran. This infection is one of the most severe liver virus infections in the world. Due to the effect of early detection, care and treatment of Hepatitis B disease, robust, fast, sensitive and inexpensive analytical devices are highly needed. In this study, an ultra-high-sensitivity label free probe to detect the Hepatitis B virus by the formation of the film of Pd(II)-Al(III)LDH was made for the first time as a substrate on the surface of the fluorinated tin oxide electrode (FTO). The complementary DNA sequence of the amino-labeled DNA was fixed as a probe on the carboxylic group-directed LDH film. The DNA of the virus was attached to the complementary sequence and a significant change was observed in the response of the probe amperemeter in the presence of the Fe (CN)63- /4- solution. The wide linear range 1 fM -1 μM and the detection limit of 1 fM probe indicate the high performance of this biomarker. Finally, a biosensor was used to measure the DNA of the Hepatitis B virus in a human blood sample. Designed biosensors are highly sensitive and have other advantages, including short design and production time, quick and easy to use, and commercializable as portable kits.
Keywords: L-Cysteine; Co–Al LDH; electrodeposition; differential pulse voltammetry; Disposable electrode; acetylcysteine; Hepatitis B
