title: Impedance based detection of pathogenic E. coli O157:H7 using a ferrocene-antimicrobial peptide modified biosensor.
abstract: Escherichia coli O157:H7 can cause life-threatening gastrointestinal diseases and has been a severe public health problem worldwide in recent years. A novel biosensor for the detection of E. coli O157:H7 is described here using a film composed of ferrocene-peptide conjugates, in which the antimicrobial peptide magainin I has been incorporated as the biorecognition element. Electrochemical impedance spectroscopy was employed to investigate the surface characteristics of the newly developed biosensor and to monitor the interactions between the peptide film and the pathogenic bacteria. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to confirm the immobilization of ferrocene-conjugate onto the gold surface. Non-pathogenic E. coli K12, Staphylococcus epidermidis and Bacillus subtilis were used in this study to evaluate the selectivity of the proposed biosensor. The results have shown the order of the preferential selectivity of the method is E. coli O157:H7>non-pathogenic E. coli>gram positive species. The detection of E. coli O157:H7 with a sensitivity of 10(3)cfu/mL is enabled by the biosensor. The experimental conditions have been optimized and the plot of changes of charge transfer resistance (ΔRCT) and the logarithm of the cell concentration of E. coli O157:H7 shows a linear correlation in the range of 10(3)-10(7)cfu/mL with a correlation coefficient of 0.983.
authors.affiliation: Department of Sanitary Chemistry, Public Health School, West China Medical Center, Sichuan University, Chengdu 610044, PR China; Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Rouzbeh
authors.initials: R
authors.lastname: Afrasiabi
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Farkhondeh
authors.initials: F
authors.lastname: Fathi
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada; Department of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, PR China.
authors.forename: Cuili
authors.initials: C
authors.lastname: Xiang
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Love
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada.
authors.forename: Zhe
authors.initials: Z
authors.lastname: She
authors.affiliation: Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada. Electronic address: bernie.kraatz@utoronto.ca.
authors.forename: Heinz-Bernhard
authors.initials: HB
authors.lastname: Kraatz
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D058491:Bacterial Load / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D019453:Escherichia coli O157 / Q000737:chemistry* / Q000302:isolation & purification*; D005296:Ferrous Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D000075163:Metallocenes; D008839:Microelectrodes
chemical_list: D023181:Antimicrobial Cationic Peptides; D005296:Ferrous Compounds; D000075163:Metallocenes; D006046:Gold; C004998:ferrocene
keywords: Bioconjugate; Bioorganometallic; E. coli; Ferrocene; Peptide