title: Label-free electrochemical immunoassay for the detection of human chorionic gonadotropin hormone.
abstract: Here we report on a new and rapid immunoassay for the label-free voltammetric detection of human chorionic gonadotropin hormone (hCG) in urine. Monitoring the changes in the current signals of antibodies (Abs) before and after the binding of the antigen (Ag) provides the basis for an immunoassay that is simple, rapid, and cost-effective. Since hCG is found at highly elevated levels in pregnant female urine with the range of 30,000-200,000 mIU/mL (approximately 30-200 nM) by 8-10 weeks into pregnancy, its label-free electrochemical detection was achieved by using our method. The coverage of the electrode surface with the Ab and the incubation time with the target Ag were optimized for the detection of hCG. The limit of detection of our method was calculated to be 15 pM (n = 3, approximately 15 mIU/mL) in synthetic hCG samples and 20 pM (n = 3, approximately 20 mIU/mL) in human urine. The electrochemical results for the detection of hCG in the urine samples were in agreement with the results obtained using a reference system, enzyme-linked immunosorbent assay. Further research about the intrinsic electroactivity of Abs and their target molecules would surely provide new and sensitive screening assays, as well as extensive data regarding their interaction mechanisms.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi City, Ishikawa, 923-1292 Japan. kkerman@jaist.ac.jp
authors.forename: Kagan
authors.initials: K
authors.lastname: Kerman
authors.forename: Naoki
authors.initials: N
authors.lastname: Nagatani
authors.forename: Miyuki
authors.initials: M
authors.lastname: Chikae
authors.forename: Teruko
authors.initials: T
authors.lastname: Yuhi
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Takamura
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tamiya
mesh_terms: D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology; D000937:Antigen-Antibody Reactions; D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000276:immunology; D004563:Electrochemistry; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D011247:Pregnancy; D011994:Recombinant Proteins / Q000032:analysis / Q000276:immunology; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin; D011994:Recombinant Proteins