A dual-mode aptasensor based on microbial endogenous cytochrome self-activated dual-enzyme cascade response for Pseudomonas aeruginosa detection and in-situ sterilization.

In-situ sterilization following detection is a challenge in microbiological detecting. Herein, we propose a dual-mode aptasensor for detecting Pseudomonas aeruginosa and achieving in-situ sterilization for the first time. Specifically, upon capture of P. aeruginosa by the histidine-modified aptamer-functionalized magnetic nanozyme (PA@HIS-MBs), the endogenous c-type cytochromes (c-cyts) of the bacterium and HIS-MBs established a dual peroxidase-like (POD-like) activities cascade system. H2O2-catalyzed reactive oxygen species (ROS) simultaneously oxidized TMB (3,3′,5,5′-tetramethylbenzidine) (colorimetric mode), in synergy with the photothermal effect of PA@HIS-MBs, achieved in-situ sterilization. Simultaneously, electrochemical impedance enabled accurate quantitative detection. Ultimately, the detection limits for the dual-mode aptasensor were 0.481 CFU/mL (colorimetric mode) and 0.401 CFU/mL (impedance mode), respectively. Furthermore, this aptasensor not only exhibited good matrix effect performance (|ME|< 10%), but also delivered results consistent with quantitative polymerase chain reaction (qPCR) across three meat samples. It provided a universal platform for accurate, and rapid detection and in-situ sterilization of pathogenic bacteria, with potential for extension to other pathogenic bacteria.