Detection of GDF15 Protein Using Ultrabroadband Ferromagnetic Resonance of Magnetic Nanoparticles

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This study proposed a protein detection method of the Growth Differentiation Factor-15 (GDF15) using a ultra-broadband microstrip line type probe up to 67 GHz. We prepared samples that bound the GDF15 and magnetic nanoparticles (MNPs) using primary and secondary antibodies. High-density secondary MNPs reacted with antigen several times to enhance the magnetic signal using a biotin-avidin reaction on a cover glass. The reaction between the antigen and the MNPs was confirmed by fluorescent particles and a vibrating sample magnetometer (VSM). The application of the DC field enhanced sharp ferromagnetic resonance (FMR), improving the signal-to-noise ratio for GDF15 detection. The difference in FMR intensity between 1.5 T and 2 T increased clearly with increasing GDF15 concentration (0, 0.01, 0.1, and 1 μg/ml). A reproducible calibration curve was obtained for protein (GDF15) detection. Our method shows promise for sensitive and quantitative protein detection in biomedical applications.