An electrochemical aptasensor has been developed to detect Acinetobacter baumannii (A. baumannii). The proposed system was developed by modifying carbon screen-printed electrodes (CSPE) with a synthesized MWCNT@Fe3O4@SiO2-Cl nanocomposite and then binding A. baumannii-specific aptamer using covalent immobilization on the modified electrode surface, and the interaction of methylene blue (MB) with Apt as an electrochemical redox indicator. As a result of the incubation of the A. baumannii bacteria as a target on the proposed aptasensor, a cathodic peak current density (Jpc) of MB decreased due to the formation of the Apt-A. baumannii complex and MB being released from the immobilized Apt on the surface of the modified electrode. In addition to increasing the electron transfer kinetics, the nanocomposite provides a relatively stable matrix to improve the loading Apt sequence. The suggested aptasensor was demonstrated to be capable of detecting A. baumannii with a linear range of 10.0 – 1.0×107 Colony-forming unit (CFU) mL-1 and a detection limit of 1 CFU mL-1 (S/N=3) using differential pulse voltammetry (DPV) studies at a working potential of ~ 0.29 V and a scan rate of 100 mV s−1. The outcomes revealed that the aptasensor exhibited high A. baumannii detection sensitivity, stability, reproducibility, and specificity.
