title: Magnetic nanocomposite of anti-human IgG/COOH-multiwalled carbon nanotubes/Fe₃O₄ as a platform for electrochemical immunoassay.
abstract: An electrochemical immunosensing method was developed based on a magnetic nanocomposite. The multiwalled carbon nanotubes (MWCNTs) were treated with nitric acid to produce carboxyl groups at the open ends. Then, Fe₃O₄ nanoparticles were deposited on COOH-MWCNTs by chemical coprecipitation of Fe²⁺ and Fe³⁺ salts in an alkaline solution. Goat anti-human IgG (anti-hIgG) was covalently attached to magnetic nanocomposite through amide bond formation between the carboxylic groups of MWCNTs and the amine groups of anti-hIgG. The prepared bio-nanocomposite was used for electrochemical sensing of human tetanus IgG (hIgG) as a model antigen. The anti-hIgG magnetic nanocomposite was fixed on the surface of a gold plate electrode using a permanent magnet. The hIgG was detected using horseradish peroxidase (HRP)-conjugated anti-hIgG in a sandwich model. Electrochemical detection of hIgG was carried out in the presence of H₂O₂ and KI as substrates of HRP. Using this method, hIgG was detected in a concentration range from 30 to 1000 ng ml⁻¹ with a correlation coefficient of 0.998 and a detection limit of 25 ng ml⁻¹ (signal/noise=3). The designed immunosensor was stable for 1 month.
authors.affiliation: Laboratory of Microanalysis, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
authors.forename: Hajar
authors.initials: H
authors.lastname: Zarei
authors.forename: Hedayatollah
authors.initials: H
authors.lastname: Ghourchian
authors.forename: Khadijeh
authors.initials: K
authors.lastname: Eskandari
authors.forename: Majid
authors.initials: M
authors.lastname: Zeinali
mesh_terms: D004563:Electrochemistry / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007074:Immunoglobulin G / Q000737:chemistry*; D058185:Magnetite Nanoparticles; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites; D037742:Nanotubes, Carbon; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005290:Ferric Compounds; D007074:Immunoglobulin G; D058185:Magnetite Nanoparticles; D037742:Nanotubes, Carbon; C000499:ferric oxide