Molecularly imprinted polymer combined with MOF-assisted redox recycling amplification: A powerful electrochemical sensing strategy for pathogenic bacteria

Rapid and sensitive determination of foodborne pathogenic bacteria at a low cost is crucial for ensuring food safety monitoring and diagnosing bacterial infections. In this protocol, we propose an electrochemical sandwich-type biosensor for highly sensitive detection of bacteria based on a bacterial imprinted polymer film (BIF) and metal-organic frameworks (MOF)-assisted redox recycling amplification. The BIF is formed in-situ through electropolymerization (EP) and template removal on the electrode surface, while aptamers are assembled on nanogold-modified MOF to create signal nanoprobes with target recognition ability. The BIF-modified electrode effectively captures the target bacteria and subsequently forms a sandwich structure through conjugation with signal nanoprobes, enabling efficient adsorption of methylene blue (MB). This facilitates the redox recycling of Fe(II) from the electroactive [Fe(CN)6]3-/4- in testing buffer assisted by MB, thereby generating a significantly amplified anodic current of [Fe(CN)6]3-/4- for precise quantitation. By utilizing the selective BIF interface and MOF-assisted redox recycling amplification, our method demonstrates excellent analytical performance with a low limit of detection (LOD) of 1 CFU mL-1, a broad detection range spanning from 10 to 108 CFU mL-1, and high selectivity. The feasibility of applying this approach for detecting bacteria in complex samples highlights its significant potential in areas related to food safety and public health.