Nanoparticles-based electrochemical sensing platform for high-through immunoassay with redox-activity CaCO₃ nanotags...

A new nanoparticles-based sensing platform was designed for high-through electrochemical immunoassay of ferritin (FET) biomarker on a magneto-controlled microfluidic device by using anti-FET capture antibody-conjugated magnetic sensing probes. Thionine-doped calcium carbonate (CaCO₃) nanoparticles labeled with anti-FET detection antibodies were utilized as the recognition elements. Introduction of target FET caused the sandwich-type immunoreaction between two antibodies. The formed immunocomplexes were attached onto magnetic microfluidic sensing interface through an external magnet. Subsequently, the carried CaCO₃ nanoparticles were dissolved under acidic conditions to release the doped thionine molecules with redox activity. The thionine-based voltammetric signals increased with the increment of target FET levels within the linear range 0.01-100 ng mL^-1. The limit of detection was 7.9 pg mL^-1 FET. Good analytical properties such as selectivity, reproducibility, and accuracy were achieved with the nanoparticles-based magnetic electrochemical immunoassay. More significantly, the magnetic microfluidic electrochemical immunoassay provides new opportunities for rapid, simple, and cost-effective serum sample analysis.