Scaling Characteristics of the Magnetization Increments of Functionalized Nanoparticles Determined Using a Vibrating Sample Magnetometer for Liquid Magnetic Immunoassays

Here, scaling the normalized increment of dc magnetic susceptibility (Δ χ /χ) to a characteristic logistic function provides a foundation for characterizing unknown quantities of biomarkers. We report the scaling behavior of magnetization increments in reagents composed of biofunctionalized magnetic nanoparticles (BMNs) conjugated with biotargets for liquid magnetic immunoassays. We measured hysteresis loops and obtained the increment of magnetization (Δ M) after binding the C-reactive protein (CRP) to Fe₃O₄-anti-CRP. The results show that Δ M increased when the concentration of CRP increased. There was enhanced Δ M generated from magnetic clusters composed of Fe₃O₄-anti-CRP-CRP. The present platform is robust, easy to use, and can be applied to assays for various biomolecules for tumor markers, viruses, and proteins.