Electrophoretically deposited carbon nanotube-based reagent-free aptasensor for point of care detection of Pseudomonas aeruginosa in urine samples

Increasing incidences of pathogenic bacterial outbreaks, together with growing environmental and public health concerns, have accelerated the development of electrochemical point-of-care (POC) diagnostic systems that are rapid, reliable, and cost-effective, offering high specificity and sensitivity for the on-site detection of bacterial pathogens. Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen and it is also causing nosocomial infections and poses significant challenges to public health. In this study, we demonstrate a reagent-free electrochemical aptasensor for the highly sensitive detection of Pseudomonas aeruginosa . The redox label methylene blue (MB) was covalently linked to an amino-modified aptamer, which binds selectively to the target bacteria, enabling electron transfer quantification through square-wave voltammetry (SWV). Screen-printed carbon electrodes (SPCEs) were modified with carboxylated multi-walled carbon nanotubes (c-MWCNTs) via an electrophoretic deposition technique to enhance surface conductivity and signal response. The developed aptasensor exhibited a linear dynamic range (LDR) from 1 × 10 1 to 1 × 10 7 colony-forming units (CFU)/mL, with an impressive limit of detection (LOD) of 1 CFU/mL. The reagent-free electrochemical aptasensor was successfully validated using undiluted urine samples spiked with Pseudomonas aeruginosa . Overall, the fabricated aptasensor demonstrates strong potential as a powerful diagnostic tool for the rapid and sensitive detection of Pseudomonas aeruginosa in clinical and environmental samples. • Reagent-free MB-aptamer system enables simplified, on-site P. aeruginosa detection • EPD-assembled c-MWCNT network on SPCEs enhances conductivity and aptamer loading • Achieves 1 CFU mL -1 sensitivity with a broad linear range of 10 1 –10 7 CFU mL -1 • High specificity with validated performance in undiluted human urine samples • Low-cost, disposable platform detects bacteria in real matrices (diapers/pads)