Magnetic nanoparticle spectroscopy for multiplex detection: Insights from frequency mixing magnetic detection

Magnetic nanoparticles (MNPs) have shown promising applications in the field of biomedical sciences. Subsequently, various types of Magnetic Particle Spectroscopy (MPS) have been proposed for quantitative and qualitative analysis of MNPs. Among the various functions of MPS proposed so far, the development of technology that can analyze multiplex detection of different types of MNPs has attracted due to the expansion of various application fields. For example, the technology can be applied to enhance efficiency in biosensors, process analysis in MNP manufacturing, and measurement of various diseases in MPI. In our investigation, we perform a comparative study of different commercially available MNPs for use in multiplex detection applications using the frequency mixing magnetic detection (FMMD) technique. In this method, we employ a low-frequency magnetic field scanning method and analyze the real and imaginary parts of the measurement signal f 1 + 2 ·f 2 obtained from binary mixture samples of different MNP type combinations. Our findings suggest that FMMD-based duplex detection can achieve effective and reliable differentiation when a substantial phase response deviation exists among the particles. • The constituent ratio of binary magnetic nanoparticle mixtures can be determined by frequency mixing magnetic detection. • Variation of the low frequency magnetic excitation amplitude and amplitude/phase analysis of the nonlinear response enables distinction of the mixture constituents. • The method can be used to distinguish different analytes in multiparametric magnetic immunoassays.