摘要
An integrated magnetoimpedance (MI) biosensor microfluidic magnetic platform was proposed for the evaluation of of cardiac markers cardiac troponin-I (cTnI). The bioanalytes evaluation platform mainly contained external permanent magnets (PMs), MI elements, peelable SiO2film units and microfluidic chip (MFC). The MI elements were made of micro-electro-mechanical system (MEMS)-based multilayered [Ti(6 nm)/FeNi(100 nm)]5/Cu(400 nm)/[Ti(6 nm)/FeNi(100 nm)]5 thin films and designed as meander structures with closed magnetic flux. The MFC was fabricated by using 3D printing and inverted molding techniques, and designed with a solution mixing reaction region, a magnetic separation region and detection regions. Peelable SiO2 film units with the same size as the MI sensing element are used for bioanalytes immunoreactivity interface. Two large PMs were placed directly below the MI sensing unit to provide a bias magnetic field, and the smaller PM was embedded in MCF for magnetic separation function. The different concentration biological target (cTnI antigen), PBS buffer and Dynabeads labeled polyclonal cTnI antibody solution are injected sequentially into the MCF. After immunoreactivity and magnetic separation, a classical sandwich immunoreaction process occured on the surface of the monoclonal antibody-modified SiO2 film via self-assembling technology in the reaction region of MFC. The fundamental principle for evaluation of cTnI was based on variation of the MI signal under different concentration biological target coupled with different number of Dynabeads. It was demonstrated that the mentioned MI-based magnetic platform can perform detection analyses over a range of cTnI concentrations (lowest concentration 0.1 ng/ml and highest concentration 100 ng/ml). The proposed MI-based magnetic platform provides a sensitive, reliable, stable and reusable bioanalytical platform and has potential for future biomedical applications.
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