A Signal-Amplified Piezoelectric Sensor for the Detection of hs- CRP Using HRP Doped Magnetic Core-Shell FeO@SiO@Au Nanostructures as Labels

Abstract

A highly sensitive and signal-amplified electrochemical immunoassay for high sensitivity C reaction protein (hs-CRP) has been developed based on an enzyme-catalyzed amplification due to the formation of an insoluble precipitate on the surface of a piezoelectric electrode. A novel horseradish peroxidase (HRP) and CRP antibody co-immobilized magnetic core-shell [email protected]@Au nanostructures ([email protected] @Au-HRP-anti CRP-HRP) was synthesized and employed as labels for detection of CRP. After sandwich-type immunoreactions between CRP and labels on 96-well micro-titer plate, the immunocomplex on the bottom was subsequently exposed to 3-Amino-9-ethylcarbazole (AEC). The HRP labeled on labels can biocatalyze AEC in the presence of H2O2, resulting in an insoluble product. When the product solution was dropped on the piezoelectric electrode’s surface, it can achieve an obviously decreased of frequency(△f). The amount of precipitation was found proportional to CRP within a certain range of concentration from 0.01 to 200 ng mL-1 with a low detection limit of 3 pg mL-1. Comparing with the conventional ELISA, the immunoassay with the proposed amplified procedure shows improved sensitivity due to the significantly elevated amount of HRP labeled which can significantly amplify the subsequent enzyme catalysis reaction. It can be used to quantitatively determine other biomarker in the sample of human serum if changed the detection antibody.