Electrochemical immunosensor for receptor tyrosine kinase AXL using poly(pyrrolepropionic acid)-modified disposable electrodes

A sensitive and rapid method for the determination of the clinically relevant biomarker receptor tyrosine kinase AXL in serum involving amperometric disposable immunosensors is reported. The target protein was sandwiched between a specific capture antibody covalently immobilized on screen-printed carbon electrodes modified with electropolymerized poly(pyrrolepropionic acid) and a biotinylated detector antibody labeled with a streptavidin-horseradish peroxidase conjugate. The amperometric responses were measured at −0.20 V vs the Ag pseudo-reference electrode of the SPCE upon the addition of H2O2 in the presence of hydroquinone (HQ) as mediator. This integrated immunosensing platform showed a low limit of detection (337 pg mL−1), a good selectivity against other non-target serum proteins, and provided results statistically in agreement with those obtained by using a commercial ELISA kit. These attractive features together with the simplicity and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site clinical analysis.
The financial support of projects: Retos Colaboración RTC2015-4184-1 (cofinanced by the Ministry of Economy and Competitivity and FEDER), CTQ2015-70023-R and CTQ2015- 64402-C2-1-R (Spanish Ministry of Economy and Competitivity Research Projects) and S2013/MT-3029 (NANOAVANSENS Program from the Comunidad de Madrid) are gratefully acknowledged. R.M. Torrente-Rodríguez acknowledges a predoctoral contract from the Spanish Ministerio de Economía y Competitividad.