title: Highly sensitive electrochemical aptasensor for immunoglobulin E detection based on sandwich assay using enzyme-linked aptamer.
abstract: Here, we describe the fabrication of an electrochemical immunoglobulin E (IgE) aptasensor using enzyme-linked aptamer in the sandwich assay method and thionine as redox probe. In this protocol, 5'-amine-terminated IgE aptamer and thionine were covalently attached on glassy carbon electrode modified with carbon nanotubes/ionic liquid/chitosan nanocomposite. Furthermore, another IgE aptamer was modified with biotin and enzyme horseradish peroxidase (HRP), which attached to the aptamer via biotin-streptavidin interaction. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were performed at each stage of the chemical modification process to confirm the resulting surface changes. The presence of IgE induces the formation of a double aptamer sandwich structure on the electrode, and the electrocatalytic reduction current of thionine in the presence of hydrogen peroxide was measured as the sensor response. Under optimized conditions and using differential pulse voltammetry as the measuring technique, the proposed aptasensor showed a low detection limit (6 pM) and high sensitivity (1.88 μA nM(-1)). This aptasensor also exhibited good stability and high selectivity for IgE detection without an interfering effect of some other proteins such as bovine serum albumin (BSA) and lysozyme. The application of the aptasensor for IgE detection in human serum sample was also investigated. The proposed protocol is quite promising as an alternative sandwich approach for various protein assays.
authors.affiliation: Department of Chemistry, University of Kurdistan, 66177-15175 Sanandaj, Iran; Research Center for Nanotechnology, University of Kurdistan, 66177-15175 Sanandaj, Iran. Electronic address: absalimi@uok.ac.ir.
authors.forename: Abdollah
authors.initials: A
authors.lastname: Salimi
authors.affiliation: Department of Chemistry, University of Kurdistan, 66177-15175 Sanandaj, Iran.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Khezrian
authors.affiliation: Department of Chemistry, University of Kurdistan, 66177-15175 Sanandaj, Iran; Research Center for Nanotechnology, University of Kurdistan, 66177-15175 Sanandaj, Iran.
authors.forename: Rahman
authors.initials: R
authors.lastname: Hallaj
authors.affiliation: Department of Animal Science, Faculty of Agricultural Science, University of Kurdistan, 66177-15175 Sanandaj, Iran.
authors.forename: Asaad
authors.initials: A
authors.lastname: Vaziry
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001681:Biological Assay / Q000379:methods*; D002417:Cattle; D055664:Electrochemical Techniques; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis* / Q000737:chemistry; D057230:Limit of Detection; D008855:Microscopy, Electron, Scanning; D009101:Multiple Myeloma / Q000175:diagnosis; D012710:Serum Albumin, Bovine / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D012710:Serum Albumin, Bovine; D007073:Immunoglobulin E; D006735:Horseradish Peroxidase
keywords: Carbon nanotubes; Chitosan; Electrochemical aptasensor; Enzyme-linked sandwich assay; IgE; Ionic liquid