Yu-Kai Su

Here, scaling the normalized increment of dc magnetic susceptibility (Aχ/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 (AM) after binding the C-reactive protein (CRP) to Fe ₃ O ₄ -anti-CRP. The results show that AM increased when the concentration of CRP increased. There was enhanced AM generated from magnetic clusters composed of Fe ₃ O ₄ -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.

In this work, we report characterizations of biofunctionalized magnetic nanoparticles (BMNPs) associated with alpha-fetoprotein (AFP) for biomedical applications. The example BMNP in this study is anti-alpha-fetoprotein (anti-AFP) conjugated onto dextran-coated Fe₃O₄ labeled as Fe₃O₄-anti-AFP, and the target is AFP. We characterize magnetic properties, such as increments of magnetization ΔM_H and effective relaxation time Δτ_eff in the reaction process. It is found that both ΔM_H and Δτ_eff are enhanced when the concentration of AFP, Ф_AFP, increases. The enhancements are due to magnetic interactions among BMNPs in magnetic clusters, which contribute extra M_H after the association with M_H and in turn enhance τ_eff. The screening of patients carrying hepatocellular carcinoma (HCC) is verified via ΔM_H/M_H. The proposed method can be applied to detect a wide variety of analytes. The scaling characteristics of ΔM_H/M_H show the potential to develop a vibrating sample magnetometer system with low field strength for clinic applications.