title: Layer-by-layer assembly of gold nanoparticles and cysteamine on gold electrode for immunosensing of human chorionic gonadotropin at picogram levels.
abstract: The development of an electrochemical immunosensor for the detection of human chorionic gonadotropin (hCG) is described with a limit of detection as low as 0.3 pg mL(-1) in phosphate buffer. In this immunosensor, cysteamine (Cys) and gold nanoparticles (AuNPs) were used to immobilize an anti-hCG monoclonal antibody onto a gold electrode (GE). The structure of AuNPs has been confirmed by EDS, SEM, and TEM analysis. Due to the large specific surface area and excellent electrical conductivity of AuNPs, electron transfer was promoted and the amount of hCG antibody was enhanced significantly. A systematic study on the effects of experimental parameters such as pH, incubation time in the hCG solution and urea solution used for experiments on the binding between the immobilized antibody and hCG has been carried out. Under optimal experimental parameters, differential pulse voltammetry (DPV) signal changes of the [Fe(CN)6](3-/4-) are used to detect hCG with two broad linear ranges: 0.001 to 0.2 and 0.2 to 60.7 ng mL(-1). The LOD value proves more sensitive in comparison with previously reported methods. The prepared immunosensor showed high sensitivity and stability. In addition, the immunosensor was successfully used for the determination of hCG in human serum.
authors.affiliation: Department of Chemistry, Ilam University, P.O. Box, 69315-516, Ilam, Iran. Electronic address: mahmoudroushani@yahoo.com.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Roushani
authors.affiliation: Department of Chemistry, Ilam University, P.O. Box, 69315-516, Ilam, Iran.
authors.forename: Akram
authors.initials: A
authors.lastname: Valipour
authors.affiliation: Department of Chemistry, Payame Noor University, P.O. Box, 19395-3697, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Valipour
mesh_terms: D055910:Antibodies, Immobilized / Q000276:immunology; D015374:Biosensing Techniques; D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000097:blood / Q000276:immunology; D003543:Cysteamine / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D005292:Ferricyanides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D013997:Time Factors; D014508:Urea / Q000737:chemistry
chemical_list: D055910:Antibodies, Immobilized; D006063:Chorionic Gonadotropin; D005292:Ferricyanides; C007931:hexacyanoferrate III; D003543:Cysteamine; D006046:Gold; D014508:Urea
keywords: Cysteamine; Electrochemical immunosensor; Electrodeposition of AuNPs; Human chorionic gonadotropin