Fabrication of a highly sensitive conductive copolymer layer modified immunosensing tool for cytokeratin-19 fragment detection

Abstract

Design of a new and highly selective impedimetric biosensor based on the immobilization of a fragment of cytokeratin subunit 19 (CYFRA 21-1)-specific antibodies onto a conductive copolymer layer (poly(epoxy-substituted thiophene)-co-poly(3,4-ethylenedioxythiophene), CCL)-coated indium tin oxide (ITO) for the determination of CYFRA 21-1 in serum samples was reported. CCL was applied as a working electrode-modifying reagent to prepare the surface of the working ITO electrode, and CYFRA 21-1-specific antibodies bound to epoxy ends present in the copolymer layer matrix. The impedimetric response of the immunosensor to CYFRA 21-1 was recorded, and the signaling mechanism of the suggested immunosensor was based on an increase in the charge transfer resistance in the presence of target CYFRA 21-1. The developed biosensor exhibited excellent selectivity for CYFRA 21-1, and it could detect CYFRA 21-1 in a linear dynamic range from 0.0125 to 35 pg/mL with a limit of quantification (LOQ) of 12.25 fg/mL. The designed biosensor showed good storage stability, high sensitivity, suitable repeatability and reproducibility, and acceptable long-term stability. The clinical analysis of the manufactured immunosensor was explored for the analysis of serum samples, and high recoveries and good relative standard deviations (RSDs) were obtained in the range of 97.01 and 103.17 %, respectively. This copolymer-based biosensor could be a feasible tool for clinical diagnosis in complex serum samples.