A flexible giant magnetoimpedance-based biosensor for the determination of the biomarker C-reactive protein

We report on a method for the determination of magnetic bead-labeled C-reactive protein (CRP), a biomarker of cardiovascular diseases and inflammations. It is using a flexible giant magnetoimpedance (GMI)-based platform. Micro-patterned GMI sensing elements were prepared from a cobalt-based commercial amorphous ribbon (Metglas® 2714A) using micro electro-mechanical system (MEMS) technology. A gold film was then deposited on the GMI sensing element to act as a support for the immuno platform. Sandwich assays are performed using antibody-antigen combinations and biotin-streptavidin interactions on the gold film substrate surface via self-assembled layers. The GMI ratios of the sensors with different concentrations of antigen against CRP were investigated. The results show that the presence of CRP antigens on the biosensor improves the GMI effect owing to the induced magnetic dipole of superparamagnetic beads, and that the GMI ratios show distinct changes at high frequency. This bioassay for CRP has a linear detection range between 1 to 10 ng·mL −1 . This new method in our perception provides a widely applicable basis for rapid diagnostic testing and will pave the way for future development of electrochemical point-of-care diagnostic devices for cardiac diseases. (a) Graphical illustration of CRP test setup. (b) Magnetic field arrangement of the beads under an applied magnetic field. (c) GMI changes in relation to the concentration of the CRP