title: Ultrasensitive determination of human growth hormone (hGH) with a disposable electrochemical magneto-immunosensor.
abstract: In this paper, an electrochemical magneto-immunosensor for the detection of human growth hormone (hGH) is described for the first time. The immunosensor involves the use of tosyl-activated magnetic microparticles (TsMBs) to covalently immobilize a monoclonal mAbhHG antibody. A sandwich-type immunoassay with a secondary pAbhGH antibody and anti-IgG labelled with alkaline phosphatase (anti-IgG-AP) was employed. TsMBs–mAbhGH–hGH–pAbhGH–anti-IgG-AP conjugates were deposited onto the surface of a screen-printed gold electrode using a small neodymium magnet, and electrochemical detection was performed by square-wave voltammetry upon the addition of 4-aminophenyl phosphate as the AP substrate. All the variables involved in the preparation of immunoconjugates and in the immunoassay protocol were optimized. A calibration curve for hGH was constructed with a linear range between 0.01 and 100 ng/mL (r = 0.998) and a limit of detection of 0.005 ng/mL. This value is nearly three orders of magnitude lower than that obtained using surface plasmon resonance (Treviño et al., Talanta 78:1011-1016, 2009). Furthermore, good repeatability, with RSD = 3% (n = 10) at the 1-ng/mL hGH level, was obtained. Cross-reactivity studies with other hormones demonstrated good selectivity. The magneto-immunosensor was applied to the analysis of human serum spiked with hGH at the 4- and 0.1-ng/mL levels. Mean recoveries of 96 ± 6% and 99 ± 2%, respectively, were obtained.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Serafín
authors.forename: N
authors.initials: N
authors.lastname: Úbeda
authors.forename: L
authors.initials: L
authors.lastname: Agüí
authors.forename: P
authors.initials: P
authors.lastname: Yáñez-Sedeño
authors.forename: J M
authors.initials: JM
authors.lastname: Pingarrón
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D019382:Human Growth Hormone