Novel ultrasensitive impedimetric biosensor for rapid detection of Pseudomonas aeruginosa via recombinant...

Pseudomonas aeruginosa is a ubiquitous and intractable pathogenic bacterium known for causing severe infections in immunocompromised individuals. Rapid and sensitive detection of this pathogen is therefore critically important in clinical diagnostics, food safety testing, and environmental monitoring. In this study, the lectin LecB, which has a high specificity for α-D-mannose residues in the Psl polysaccharides on P. aeruginosa cell surface, was chosen as the biorecognition element for detecting P. aeruginosa. First, the high specificity of LecB towards α-D-mannose was analyzed and verified by molecular docking and isothermal titration calorimetry. A novel impedimetric electrochemical biosensor was then constructed by modifying a glassy carbon electrode (GCE) with a biocomposite of recombinant LecB and nanoporous gold (NPG). Notably, this work represents the first report of an impedimetric biosensor employing a recombinant LecB-functionalized NPG biointerface for the rapid and sensitive detection of P. aeruginosa. In detecting operation, the charge transfer resistance (R_ct) of the LecB/NPG/GCE biosensor increased linearly with the logarithm of P. aeruginosa concentration over the range of 10-10⁶ CFU mL^-1, with a detection limit of 10 CFU mL^-1. Furthermore, the LecB/NPG/GCE biosensor successfully quantified P. aeruginosa in tap water, milk, and human serum samples, achieving recovery rates of 93.05%-119.63% with relative standard deviations below 7.85%. The LecB/NPG/GCE biosensor offered several practical advantages, including high sensitivity, rapid detection, cost efficiency, ease of fabrication, and adaptability. These features make it a promising candidate for clinical diagnostics, food safety testing, and environmental monitoring.