Early detection of cell apoptosis by a cytochrome C label-Free electrochemiluminescence aptasensor

Cytochrome c (Cyt c) is a small heme-containing metalloprotein which plays an important role in the electron transport chain in mitochondria. Monitoring Cyt c can be a key factor to find cell apoptosis process. In this work, a label-free electrochemiluminescence aptasensor for highly sensitive detection of Cyt c is introduced. We found that a new nano-based material composed of reduced graphene oxide/tris(2,2-bipyridyl) ruthenium(II) complex- cerium oxide nanoparticles- chitosan (RGO/Ru(bpy)32+-CeO2NPs- CS) can be a remarkable sensing platform in designing an electrochemiluminescence sensor. Positively charged RGO/Ru(bpy)32+-CeO2NPs-CS were placed on the surface of a Screen-Printed Carbon Electrode (SPCE), and then, negatively charged aptamer electrostatically immobilized on the modified electrode to form apta-CS-CeO2NPs-Ru(bpy)32+-RGO/SPCE. Finally the surface of the electrode was incubated with BSA to block nonspecific binding sites. In the absence of Cyt c, a weak ECL signals was produced while in the presence of Cyt c, a remarkable increase in ECL signals was observed because of detaching the aptamer from the surface and formation of aptamer-Cyt c complex. The proposed aptasensor exhibits a wide dynamic range from 0.2–100 nM (R2 = 0.993, n = 8) with a low detection limit of 25 pM which is applicable for the determination of Cyt c to find early stage apoptotic cells.