Sensitive colorimetric aptasensor for multiple foodborne pathogens detection based on PCN-Mo peroxidase-like activity

A rapid and sensitive colorimetric biosensor was developed for simultaneous detection of various pathogenic bacteria based on aptamer-mediated peroxidase (POD)-like activity of PCN-Mo nanozyme. Initially, a porphyrin-based PCN-Mo metal organic framework (MOF) nanozyme is constructed through a simple hydrothermal method, as thoroughly figured out by a series of characterization techniques. The study showed that the pathogenic bacteria aptamers could adhere to the surface of PCN-Mo, and significantly enhanced the POD-like activity by reinforcing their transport of electrons to 3,3′,5,5′-tetramethylbenzidine (TMB). In the presence of different target bacteria, the aptamers tend to bind to bacteria specifically, causing the further enhancement of POD-like activity. Based on the signal-amplification by the PCN-Mo@aptamer (PCN-Mo@Apt) nanozyme, the constructed pathogenic bacteria sensor demonstrated a wide linear range between 101 to 105 CFU/mL, with the detection limits (LODs) of 0.578, 0.439, and 0.643 CFU/mL for E. coli, S. typhimurium and S. aureus, respectively. Furthermore, the PCN-Mo sensor was capable of detection pathogenic bacteria in water, milk, classic milk tea, chicken, and beef with the recoveries of 90.1%–104.1%, indicating the sensor's practicability for pathogenic bacteria detection in real samples.