title: Development of an electrochemical immunoassay for rapid detection of E. coli using anodic stripping voltammetry based on Cu@Au nanoparticles as antibody labels.
abstract: A sensitive electrochemical immunoassay for rapid detection of Escherichia coli has been developed by anodic stripping voltammetry (ASV) based on core-shell Cu@Au nanoparticles (NPs) as anti-E. coli antibody labels. The characteristics of Cu@Au NPs before and after binding with antibody were confirmed by transmission electron microscopy (TEM). After Cu@Au-labeled antibody reacted with the immobilized E. coli on Polystyrene (PS)-modified ITO chip, Cu@Au NPs were dissolved by oxidation to the metal ionic forms, and the released Cu(2+) ions were determined at GC/Nafion/Hg modified electrode by ASV. The utilization of GC/Nafion/Hg modified electrode could enhance the sensitivity for Cu(2+) detection with a concentration as low as 9.0 x 10(-12)mol/L. Since Cu@Au NPs labels were only present when antibody reacted with E. coli, the amount of Cu(2+) directly reflected the number of E. coli. The technique could detect E. coli with a detection limit of 30CFU/mL and the overall analysis could be completed in 2h. By introducing a pre-enrichment step, a concentration of 3CFU/10mL E. coli in surface water was detected by the electrochemical immunoassay.
authors.affiliation: Department of Chemistry, East China Normal University, Shanghai 200062, PR China.
authors.forename: Xinai
authors.initials: X
authors.lastname: Zhang
authors.forename: Ping
authors.initials: P
authors.lastname: Geng
authors.forename: Huijie
authors.initials: H
authors.lastname: Liu
authors.forename: Yingqiao
authors.initials: Y
authors.lastname: Teng
authors.forename: Yajun
authors.initials: Y
authors.lastname: Liu
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Litong
authors.initials: L
authors.lastname: Jin
authors.forename: Lai
authors.initials: L
authors.lastname: Jiang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D002244:Carbon / Q000737:chemistry* / Q000276:immunology; D015169:Colony Count, Microbial / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000276:immunology / Q000302:isolation & purification*; D006046:Gold / Q000737:chemistry* / Q000276:immunology; D007118:Immunoassay / Q000295:instrumentation*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods
chemical_list: D002244:Carbon; D006046:Gold