Facile preparation of a bacteria imprinted artificial receptor for highly-selective bacterial recognition and label-free impedimetric detection.

The effective identification and quantification of pathogenic bacteria is essential for addressing serious public health issues. Here we demonstrate a simple and universal impedimetric sensor for highly selective and sensitive detection of pathogenic bacteria based on the recognition by a bacteria-imprinted polypyrrole (BIP) film. The BIP film was facilely prepared via one-step electro-polymerization followed by in-situ removal of the bacterial template. The film structure is novel with non-cavity-like imprinted sites situated at the surface of the polypyrrole (PPy) matrix, which are more accessible for the target bacteria and should enhance the mass transfer and the binding kinetics. A limit of quantitation low to 103 CFU/mL was achieved within 1 h for the detection of E.coli O157:H7, which is comparable to the antibody-based assays. Moreover, the sensor displayed remarkable selectivity, especially regarding the specific identification of bacterial serotypes. When employed to analyze E.coli O157:H7 in real drinking water, apple juice and milk samples, the sensor showed recoveries from 96.0% to 107.9% with relative standard derivations (RSDs) less than 4%. The BIP-based sensing strategy provides a universal approach for specific, selective and rapid detection of pathogenic bacteria. Compared with conventional biosensors based on biomolecular recognition, this sensor shows clear advantages including easy-of-preparation, robustness and low cost, which may hold great potential in fields of food/public safety monitoring.