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((R)) 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.