An ultrasensitive immunosensor based on tri-armed star poly(glycidyl methacrylate) polymer-coated ITO-PET electrode for detection of neuron-specific enolase in human serum

Abstract

ABSTRACTIn the present study, an ultrasensitive and simple impedimetric biosensor was fabricated for the determination of neuron-specific enolase (NSE) cancer biomarker. Anti-NSE antibody was covalently immobilised on the indium tin oxide-polyethylene terephthalate (ITO-PET) electrode surface coated with polymer Str(PGMA)3. The star poly(glycidyl methacrylate) polymer Str(PGMA)3 had epoxy side groups and these epoxy groups provided a lot of immobilisation points for antibodies. The process of immunosensor fabrication and successful immobilisation of the antibodies and antigens on the ITO-PET electrode was followed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. In addition, EIS technique was utilised for the NSE antigen quantification under optimal experimental conditions. NSE concentration was determined in the range from 0.03 pg/mL to 6 pg/mL with an ultralow detection limit of 9.1 fg/mL. Moreover, the surface topology of the modified surfaces was characterised by scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. A low detection limit, a good reproducibility, an excellent storage stability and a good selectivity were obtained. This designed biosensor was employed for the determination of NSE antigen level in human serum samples. The obtained results illustrated that this modification procedure could be applied to determine other biomarkers in human serum samples.