Development of Label-Free Impedimetric hCG-Immunosensor Using Screen-Printed Electrode

Abstract

Screen-printing (thick-film) technology is well identified as a reliable technique for fabrication of electrodes which can be used as transducer in biosensor, with several advantages including low cost, design flexibility, process automation, good reproducibility and a wide choice of materials.However, the immobilization of antibody molecules is a decisive factor for successful fabrication of immunosensors.Besides, the ability to measure human Chorionic Gonadotropin (hCG) is important in establishing the diagnosis of gestational trophoblastic disease and germ cell tumors.Moreover, Electrochemical Impedance Spectroscopy (EIS) recently has been being chosen as a main detection method because it is label-free, less destructive to the activities of biomolecule and very sensitive with comparable detection limits as optical-based sensor.In this work, a sensitive label-free impedimetric hCG-immunosensor was constructed by using a commercial screen-printing carbon ink electrode (namely Disposable Electrochemical Printed chip) as a basis.The hCG antibody was immobilized via the entrapment technique on the carbon ink electrode of DEP chip using functional molecule, 1-pyrenebutanoic acid, succinimidyl ester.The experimental results exposed that the designed immunosensor is more sensitive than other previously reported immunosensors, in the case of detection limit and linear range for antigen detection.With optimal fabrication parameters, the detection limit for α-hCG was 33 pg/mL in 10mM phosphate buffer saline (PBS) solution containing 1% bovine serum albumine (BSA).Furthermore, the use of inexpensive DEP chip as a basis for these immunosensors will allow simple instrumentation, disposable and portable at low cost.This work also demonstrates a new approach to develop a sensitive and labelfree impedimetric immunosensor based on screen-printed electrode for applications in clinical diagnosis.