A simple synthesis of a core-shell structure PPy-Au nanocomposite for immunosensing of C-reactive protein

High-sensitivity C-reactive protein (hs-CRP) is an inflammatory biomarker and can accurately predict the development of cardiovascular disease (CVD). We synthesized a core-shell structure PPy-Au nanocomposite in situ by chemically oxidizing pyrrole (Py) with HAuCl4 and the produced Au nanoparticles realized the doping in the polymerization. Analysis of morphology and energy spectrum as well as electrochemical characterization confirmed the successful one-pot synthesis. The conductive polymers with porous structure provide abundant sites for anti-CRP binding and effectively enhanced the sensitivity of the label-free BSA/anti-CRP/PPy-Au/GCE immunosensor. Its analytical performance was observed using differential pulse voltammetry (DPV), with a linear range from 0.0005 to 60 μg mL-1 and a detection limit of 0.17 ng mL-1. The platform demonstrated satisfactory selectivity, stability, and reproducibility. To validate its clinical application, we detected CRP in human serum samples with a recovery rate of 101.00-105.95% and investigated the consistency of the developed method and immunoturbidimetry with a deviation between -1.2% and +3.2%, suggesting great potential for use in point-of-care testing (POCT).