An electrochemical immunosensor for testosterone using functionalized magnetic beads and screen-printed carbon electrodes.
A disposable electrochemical immunosensor using screen-printed carbon electrodes (SPCEs) and protein A-functionalized magnetic beads (MBs) was developed for the determination of testosterone. Anti-testosterone was immobilized onto MBs and a direct competitive immunoassay involving testosterone labeled with peroxidase (HRP) was performed. The resulting conjugate was trapped on the SPCE with a small magnet. Testosterone determination was carried out by amperometry at -0.2V upon H2O2 additions using hydroquinone (HQ) as the redox mediator. The experimental variables involved in the immunosensor response to testosterone were evaluated. Under the optimized conditions, a calibration plot for testosterone was obtained with a linear range between 5.0×10(-3) and 50 ng/mL (r=0.995). The detection limit was 1.7 pg/mL and the EC50 was 0.25±0.04 ng/mL. These characteristics are notably better than those achieved with other reported immunosensors. Furthermore, anti-testosterone/MBs conjugates were shown to be stable for at least 25 days. A good selectivity was also found against other steroid hormones. The usefulness of the immunosensor was demonstrated by analyzing human serum spiked with 1 and 10 ng/mL testosterone.
Eguílaz
Marcos
M
Department of Analytical Chemistry, Faculty of Chemistry, University Computense of Madrid, Ciudad Universitaria, 28040 Madrid, Spain.
Moreno-Guzmán
María
M
Campuzano
Susana
S
González-Cortés
Araceli
A
Yáñez-Sedeño
Paloma
P
Pingarrón
José M
JM
D015374:Biosensing Techniques / Q000295:instrumentation*; D002244:Carbon / Q000737:chemistry*; D003217:Conductometry / Q000295:instrumentation*; D004209:Disposable Equipment; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018189:Immunomagnetic Separation / Q000295:instrumentation*; D013739:Testosterone / Q000097:blood* / Q000276:immunology
D013739:Testosterone; D002244:Carbon