Label-free detection of cytochrome C by a conducting polymer-based impedimetric screen-printed aptasensor

In this study we have introduced a new sensitive and selective biosensor for the determination of cytochrome C (Cyt C) as a biomarker for cell apoptosis. The biosensor is based on electrochemical entrapment of cytochrome C aptamers in a conducting polymer (polypyrrole) as dopant anions on the surface of a screen-printed carbon electrode. Morphological characterization of the proposed aptasensor was performed using Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM). Electrochemical impedance spectroscopy (EIS) as a powerful electrochemical technique was used as the detection method. The presented aptasensor shows a wide linear dynamic range for cytochrome C determination from 10 pM-1 nM. The observed limit of detection and RSD are 5 pM and 3.29%, respectively. The proposed aptasensor shows high selectivity and good stability for cytochrome C determination, even in the presence of serum proteins (e.g. lysozyme, albumin, immunoglobulin G and fibrinogen) at high concentration levels, and is successfully used as a clinical detection tool for cytochrome C detection.