A feasible and fast method to fabricate Botulinum neurotoxin serotype A (BoNT/A) biosensor was investigated by graphene-carbon paste nanocomposite electrode. In the present work, the graphene was synthesis by chemical method and characterized by SEM. The nanocomposite shows a high conductive and sensitivity for BoNT/A determination as shown by cyclic voltammetry and electrochemical impedance spectroscopy. Graphene-Carbone paste electrode was used for immobilization of aptamer in 0.1 M phosphate buffer solution at pH = 7. Aptamer was trapped in graphene modified carbon paste (Cp) electrodes. The electrodes were applied as indicator electrodes for capacitance determination of BoNT/A. Through this method, BoNT/A was detected in a concentration range from 0.16 to 0.68 ng·mL-1 with a correlation coefficient of 0.964 and detection limit of 0.09 ng·mL-1. Also, the life time of sensor is in finite.
