title: Signal-off impedimetric immunosensor for the detection of Escherichia coli O157:H7.
abstract: A signal-off impedimetric immune-biosensor based on gold nanoparticle (AuNP)-mediated electron transfer (ET) across a self-assembled monolayer (SAM) was the developed for highly sensitive detection of Escherichia coli O157:H7 bacteria. The biosensor was fabricated by covalently grafting an anti-Escherichia coli O157:H7 antibody onto SAM-modified gold electrodes. Following bacterial capture, the sensor was further modified by the gold nanoparticles (AuNPs). Due to the strong interaction between AuNPs and Escherichia coli O157:H7, AuNPs attached to the surface of the bacteria and acted as ET pathways across the insulating SAMs on the electrode surface, resulting in a significant reduction of the electron transfer resistance (Ret) between the [Fe(CN)6](3-/4-) redox probe in the solution and the substrate gold surface. Therefore, the attachment AuNPs to captured bacteria significantly enhanced the sensitivity for Escherichia coli O157:H7 bacteria detection.
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China.
authors.forename: Jingzhuan
authors.initials: J
authors.lastname: Wan
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Ai
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China.
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Geng
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gao
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Cheng
mesh_terms: D015374:Biosensing Techniques; D058266:Dielectric Spectroscopy; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000648:ultrastructure