Dual-mode electrochemical and colorimetric biosensing platform using MOF-stabilized iron nanoclusters for ultrasensitive detection of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a prevalent multidrug-resistant pathogen responsible for severe infections. Rapid, ultrasensitive, and selective detection of this bacterium is essential for effective clinical diagnostics and infection control. Here, we report a novel dual-mode biosensing platform based on two-dimensional metal-organic framework-stabilized iron nanoclusters (MOF-Fe NCs) for the simultaneous electrochemical and colorimetric detection of P. aeruginosa. The MOF-Fe NCs display synergistic properties, including exceptional electrocatalytic activity and robust peroxidase-like (POD-like) behavior. Specific capture of the target bacteria by a surface-immobilized F23 aptamer modulates electrochemical signaling and suppresses the POD-like activity for colorimetric readout. The dual-mode bioassay achieves a broad detection range from 101 to 108 CFU/mL, with detection limits of 1.7 CFU/mL (electrochemical) and 1.0 CFU/mL (colorimetric), and demonstrates high selectivity against other bacterial species. This work provides a robust, self-validating sensing strategy with significant potential for point-of-care diagnostics and real-time infection monitoring.