Nanomagnet Bioconjugates with anti‐CRP Polyclonal Antibodies as Nanobioprobes for Enhanced Impedimetric Detection of CRP.

Selective purification of biological materials for their detection in complex sample matrix is a general challenge for many researchers working in the field of diagnostics. Magnetic nanoparticles functionalized with biological molecules that impart biomolecular selectivity are therefore of major interest as capture probes thus allowing for magnetic separations. Nanoparticles can also be used for the enhanced detection of biomarkers. In this work, an ultrasensitive sandwich‐based impedimetric immunosensor was fabricated for the detection of C‐reactive protein antigen (CRPAg). Stable and oriented immobilization of anti‐CRP monoclonal antibody was achieved onto electrografted phenylethylamine derivatized with succinic anhydride and phenylboronic acid via carbodiimide chemistry. The detection of CRPAg was achieved using Electrochemical Impedance Spectroscopy (EIS). The enhancement of the impedance charge‐transfer resistance (RCT) signal was achieved using the sandwich approach. The anti‐CRP polyclonal antibody was immobilized in an oriented manner onto magnetic nanoparticles functionalized with phenylboronic acid. The increase in the change in charge‐transfer resistance (ΔRCT) values was linearly proportional to the concentration of CRPAg in the range 10 to 200 ng mL−1 covering the clinical range for CRPAg detection and with a detection limit of 0.34 ng mL−1. [ABSTRACT FROM AUTHOR]