Label-Free 3D Ag Nanoflower-Based Electrochemical Immunosensor for the Detection of Escherichia coli O157:H7 Pathogens

It is highly desirable to develop a rapid and simple method to detect pathogens. Combining nanomaterials with electrochemical techniques is an efficient way for pathogen detection. Herein, a novel 3D Ag nanoflower was prepared via a biomineralization method by using bovine serum albumin (BSA) as a template. It was adopted as a sensing interface to construct an electrochemical bacteria immunosensor for the rapid detection of foodborne pathogens Escherichia coli (E. coli) O157:H7. Bacterial antibody was immobilized onto the surface of Ag nanoflowers through covalent conjugation. Electrochemical impedance spectroscopy (EIS) was used to detect and validate the resistance changes, where [Fe(CN)(6)](3−/4−) acted as the redox probe. A linear relation between R (et) and E. coli concentration was obtained in the E. coli concentration range of 3.0 × 10(2)–3.0 × 10(8) cfu mL(−1). The as-prepared biosensor gave rise to an obvious response to E. coli but had no distinct response to Cronobacter sakazakii, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus albus, Lactobacillus easei, and Shigella flexneri, revealing a high selectivity for the detection of the pathogens down to 100 cfu mL(−1) in a short time. We believe that this BSA-conjugated 3D Ag nanoflowers could be used as a powerful interface material with good conductivity and biocompatibility for improving pathogen detection and treatment in the field of medicine, environment, and food safety. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s11671-016-1711-3) contains supplementary material, which is available to authorized users.