title: Amperometric immunosensor for the detection of Escherichia coli O157:H7 in food specimens.
abstract: A novel, label-free amperometric immunosensor has been developed for the rapid detection of heat-killed Escherichia coli O157:H7 (E. coli O157:H7). This immunosensor was prepared as follows. First, the long-chain, amine-terminated alkanethiol 11-amino-1-undecanethiol hydrochloride (AUT) was self-assembled onto a gold electrode surface to form an ordered, oriented, compact, and stable monolayer possessing -NH(2) functional groups that could immobilize massive gold nanoparticles (GNPs). Next, chitosan-multiwalled carbon nanotubes-SiO(2)/thionine (CHIT-MWNTs-SiO(2)@THI) nanocomposites and GNPs multilayer films were prepared via layer-by-layer (LBL) assembly. The surface area enhancement from the LBL assembly of the multilayer films improves the stability of the immobilized CHIT-MWNTs-SiO(2)@THI. More important, the sensitivity and stability of the immunosensor can be enhanced proportionally to the quantity of the THI mediator immobilized on the electrode surface. Finally, the E. coli O157:H7 antibody (anti-E. coli O157:H7) was covalently bound to the GNP monolayer and its bioactivity was measured by enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was employed to characterize the morphology of the MWNTs, CHIT-MWNTs, and CHIT-MWNTs-SiO(2)@THI. Under optimal conditions, the calibration curve for heat-killed E. coli O157:H7 has a working range of 4.12×10(2)-4.12×10(5) colony-forming units (CFU)/ml, and the total assay time was less than 45 min.
authors: Department of Clinical Laboratory Science, College of Medical Laboratory, Third Military Medical University, Chongqing 400038, People's Republic of China.
authors: Yan
authors: Y
authors: Li
authors: Ping
authors: P
authors: Cheng
authors: Junhua
authors: J
authors: Gong
authors: Lichao
authors: L
authors: Fang
authors: Jun
authors: J
authors: Deng
authors: Wenbin
authors: W
authors: Liang
authors: Junsong
authors: J
authors: Zheng
mesh_terms: D000473:Alkanes; D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D015374:Biosensing Techniques / Q000379:methods*; D055664:Electrochemical Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D019453:Escherichia coli O157 / Q000276:immunology / Q000302:isolation & purification*; D005516:Food Microbiology; D006046:Gold; D053768:Metal Nanoparticles / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D053761:Nanocomposites / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000648:ultrastructure; D013438:Sulfhydryl Compounds; D013499:Surface Properties
chemical_list: C510729:11-amino-1-undecanethiol; D000473:Alkanes; D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D037742:Nanotubes, Carbon; D013438:Sulfhydryl Compounds; D006046:Gold