Ultrasensitive determination of human growth hormone (hGH) with a disposable electrochemical magneto-immunosensor

• Published in: Analytical and bioanalytical chemistry Vol. 403; no. 4; pp. 939 - 946
• Main Authors: Serafin, V, Úbeda, N, Agüi, L, Yañez-Sedeño, P, Pingarron, J. M
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.05.2012; Springer
• Subjects: Analysis; Analytical Chemistry; Antibodies; Biochemistry; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Characterization and Evaluation of Materials; Chemical properties; Chemistry; Chemistry and Materials Science; Deposition; Electric properties; Electrochemistry - instrumentation; Electrochemistry - methods; Electrodes; Food Science; Hormones; Human growth hormone; Human Growth Hormone - blood; Humans; Immunoassay; Immunoassay - instrumentation; Immunoassay - methods; Immunoglobulin G; Laboratory Medicine; Magnetic alloys; Monitoring/Environmental Analysis; Original Paper; Phosphates; Sensitivity and Specificity; Somatotropin; Voltammetry; Tosyl-activated magnetic microparticles; Screen-printed electrodes; Human growth hormone; Immunosensor; Electrochemical
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-012-5753-9

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.