Recently, direct electron transfer between proteins and electrodes has been widely investigated due to its broad application in many areas. Among these proteins, the study of direct electron transfer between cytochrome c (Cyt c) and electrode has gained increasing attention. Cyt c plays an important role in the biological respiratory chain. Due to the protein denaturation it is difficult for Cytc to exhibit a voltammetric response at a bare electrode. Therefore different modified electrode widely used to this purpose. In this work an organic-inorganic nanocomposite consisting of modified TiO2 with 2, 2'-dithioxo-3, 3'-bis(3-(triethoxysilyl)propyl);(DTP) and graphen was provided for enzyme immobilization and investigate the direct electrochemistry of Cyt c. in the first step DTP was covalently attached to TiO2 nanoparticles and employed for obtaining a suitable solid surface enzyme attachment. In the second step, cyclic voltammetry used to immobilization of Cyt. c onto TiO2-DTP. The Cyt c modified electrode known as Cyt c/GO/TiO2-DTP. The voltamograms displayed a well-known and nearly symmetric redox couple corresponded to Cyt. c with a formal potential of -0.1 in PH 7.0 phosphate buffer solution (PBS). Electrochemical behavior of Cyt c/GO/TiO2-DTP was studied in different scan rate and different pH solutions. Electrocatalytic activity of modified electrode towared oxygen and hydrogen peroxide evaluated by cyclic voltammetry. The results implies to good catalytic activity of modified electrode. In order to achieved the best catalytic parameters such as detection limit and dynamic linear range hydrodynamic amperometric method was used. The results indicated that Cyt c modified electrode should be used as a good sensor for detection of hydrogen peroxide.
