A highly sensitive, selective, fast and stable electrochemical aptasensor, based on a screen-printed carbon electrode modified with a nanocomposite architecture consisting of polypyrrole and gold nanoparticles was designed for interleukin6 detection in human serum. The simultaneous presence of the conductive polymer and gold at the electrode surface provided a suitable environment for the interleukin6 specific aptamer immobilization of through sulfur-gold bonding. Cyclic voltammetry and electrochemical impedance spectroscopy were used for the monitoring, characterization and optimization of the biosensor during all the steps involved in the fabrication process. After complete optimization, the aptasensor exhibited a good impedimetric response towards the target analyte. The results showed that interleukin6 could be detected in a wide linear range from 1 pg mL(-1) to 15 mu g mL(-1) with a detection limit of 0.33 pg mL(-1). The biosensor was tested in the presence of other proteins in human serum samples with good recoveries. (C) 2017 Elsevier Ltd. All rights reserved.