title: Single domain antibody coated gold nanoparticles as enhancer for  Clostridium difficile toxin detection by electrochemical  impedance immunosensors.
abstract: This work presents a sandwich-type electrochemical impedance immunosensor for detecting Clostridium difficile toxin A (TcdA) and toxin B (TcdB). Single domain antibody conjugated gold nanoparticles were applied to amplify the detection signal. Gold nanoparticles (Au NPs) were characterized by transmission electron microscopy and UV–vis spectra. The electron transfer resistance (Ret) of the working electrode surface was used as a parameter in the measurement of the biosensor. With the increase of the concentration of toxins from 1 pg/mL to 100 pg/mL, a linear relationship was observed between the relative electron transfer resistance and toxin concentration. In addition, the detection signal was enhanced due to the amplification effect. The limit of detection for TcdA and TcdB was found to be 0.61 pg/mL and 0.60 pg/mL respectively at a signal-to-noise ratio of 3 (S/N = 3). This method is simple, fast and ultrasensitive, thus possesses a great potential for clinical applications in the future.
authors.forename: Zanzan
authors.initials: Z
authors.lastname: Zhu
authors.forename: Lianfa
authors.initials: L
authors.lastname: Shi
authors.forename: Hanping
authors.initials: H
authors.lastname: Feng
authors.forename: H Susan
authors.initials: HS
authors.lastname: Zhou
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D001426:Bacterial Proteins / Q000032:analysis* / Q000276:immunology; D001427:Bacterial Toxins / Q000032:analysis* / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D004768:Enterotoxins / Q000032:analysis* / Q000276:immunology; D004867:Equipment Design; D005243:Feces / Q000382:microbiology; D006046:Gold / Q000737:chemistry; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D057230:Limit of Detection; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D061905:Single-Domain Antibodies / Q000737:chemistry* / Q000276:immunology
chemical_list: D055910:Antibodies, Immobilized; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D061905:Single-Domain Antibodies; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile; D006046:Gold