Electrochemical Impedimetric Immunosensor for the Detection of C-Reactive Protein using ThioPhenylboronic Acid Modified Surface

Abstract

A self-assembled monolayer of 4-mercaptophenylboronic acid modified electrode was used for the detection of C-reactive protein using direct and sandwich assay format. Monoclonal mouse anti-Human CRP antibody (mAb) was used as the capture probe on the thiol-modified surface using the affinity boronate ester interaction. A polyclonal anti-CRP antibody was used as the detection antibody for signal enhancement in the sandwich assay. Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the fabrication steps of the immunosensor and immunochemical reaction between the surfacebound antibody and the antigen. The impedance change due to antibody-antigen interaction at the surface of the immunosensor was utilized for the detection of CRP. The linear detection range of this immunosensor for both assays ranged from 10-100 ng.ml-1 .The best fit for both assays were found to be y=0.0088x – 0.0536 with R2 0.9982 for the direct assay and y= 0.0139x – 0.0335 with R2 0.9997 for the sandwich assay. The detection limit for the direct and sandwich assay were 9.75and 6.23 ng.ml-1 .