Abstract: An impedimetric aptasensor based on reduced graphene oxide (rGO)/carbon nanotube (CNT)-gold nanoparticles (AuNPs) nanocomposite was prepared for the detection of Pseudomonas aeruginosa. The GO/CNT was modified on the surface of the electrode by electrodeposition, followed by electrochemicalreduction of GO. Then, electrodeposition was used to deposit AuNPs on the surface of the electrode. The working electrode was prepared by bonding thiol-modified aptamer specific for P. aeruginosa to the AuNPs composite via Au-S bonds. The morphology of the rGO/CNT-AuNPs nanocomposite was characterized by scanning electron microscopy. Cyclic voltammetry was used to monitor each assembly step. When exposed to samples containing P. aeruginosa, the anti-P. aeruginosa aptamer on the electrode could capture its target, blocking electron transport and consequently resulting in a great increase in impedance. P. aeruginosa could be quantified by the change in impedance. The linear range of this method was 10–106 CFU/mL and the detection limit was 4 CFU/mL. To the best of our knowledge, the developed electrochemical biosensor may be the most sensitive detection method for P. aeruginosa.

Key words: electrochemical impedance; aptasensor; Pseudomonas aeruginosa; reduced graphene oxide; carbon nanotube; gold nanoparticles