Ultrasensitive electrochemical aptasensor for Pseudomonas aeruginosa detection using N-doped MWCNTs/AgNPs nanocomposite

In this study, an electrochemical sensor for the specific detection of Pseudomonas aeruginosa (P. aeruginosa) was developed using an F23 aptamer-functionalized nitrogen-doped multi-walled carbon nanotubes (N doped-MWCNTs) and silver nanoparticles (AgNPs) composite. Systematic optimization of the Ag/C ratio revealed that a 1:10 composition delivers superior electrochemical performance, owing to synergistic effects between highly dispersed AgNPs and efficient nitrogen doping. Then a biosensor was constructed based on a three-electrode system, featuring a screen-printed electrode (SPE) modified with optimized N-doped MWCNTs/AgNPs-10/F23 aptamer as the working electrode. The structural and compositional characteristics of the sensor materials were systematically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance was evaluated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to assess the conductivity and charge transfer properties of the electrode materials. The sensor exhibited a wide linear detection range from 10⁻¹ to 10⁶ CFU·mL⁻¹ and the limit of detection is 0.0798 CFU·mL⁻¹, demonstrating high specificity and sensitivity for P. aeruginosa. This study demonstrates a novel strategy for developing cost-effective, portable biosensors with exceptional selectivity for bacterial pathogen detection, offering significant potential for real-time environmental monitoring and point-of-care diagnostic applications.