As the number of electro-polymerization cycles used in order to bind Cyt C onto the polymer film increased, the amount of photo-current observed also increased. These trends continued up to 60 cycles, and after 60 cycles, this increase in photo-current tend to stop. The increase in photo-current until 60 cycles can be explained by the increase in the amount of Cyt C, which consequently induces an increase in electron transfer. In addition the number of Cyt C led to increase the connection of thylakoid membranes with the electrode and this leading to increase photo-current. On the other hand, the reason photo-current reaches a saturation point, even though Cyt C is increased up to 70 and 80 cycles is thought to be related to the rapid increase in complexity of transfer paths in parallel with the increase in number of Cyt C as well as the increase in the number of cycles and consequently the decrease in conductivity and electron transfer speed. In this optimization experiment, the optimum number of cycles to bond Cyt C was determined to be 60 (Fig. 3).
Another characterization study of GE modified with P(DTP-Ph-NH2)/Cyt C /thylakoid membrane structure is the optimization of the amount of thylakoid membranes used in the execution of photosynthesis. In all of the photo-current characterization studies to date, 500 mg/ml thylakoid membrane has been bonded to gold electrodes modified with P(DTP-Ph-NH2)/Cyt C, and photo-current measurements were performed. In this optimization study, the P(DTP-Ph-NH2) polymeric film prepared by using 40 electro-polymerization cycles were obtained first. Then, the aniline-functionalized (100 mM) cytochrome-c solution was bonded to polymer-coated film through oligoaniline bonds using electro-polymerization at 60 cycles. Solutions containing 250, 500, 750 and 1000 mg/ml thylakoid membrane were immobilized on electrodes coated with P(DTP-Ph-NH2)/ Cyt C. Under 0V constant potential, 6800 W/m2 visible range light was applied to the system, and the photo-current measurements were performed in PBS.