Giant magnetoimpedance based immunoassay for cardiac biomarker myoglobin

Herein, a novel method for the detection of the cardiac biomarker myoglobin (Mb) is proposed by using an integrated giant magnetoimpedance (GMI) based immunosensor. The GMI sensor integrates magnetic sensing elements and a gold film. Micro-patterned GMI sensing elements were prepared from a cobalt-based commercial amorphous ribbon (Metglas® 2714A) using micro-electro-mechanical system (MEMS) technology. The gold film was deposited on the GMI sensing element to act as a support for the immunoplatform. The classical sandwich assay was used for the detection of Mb targeted with Dynabeads by using the antibody–antigen pair combination of biotin–streptavidin. The GMI ratios of the sensors with different concentrations of the antigen against Mb were investigated. As a result, the GMI ratios are significantly improved at high frequency if Mb is present. The sensor has a linear response in the 1 to 10 ng ml−1 concentration range, and the detection limit is 0.5 ng ml−1 at a working frequency of 10 MHz. The method is successfully applied to the determination of Mb, and can be used to detect other cardiac markers like Troponin and CK-MB.