Evaluation of Dispersibility in Liquid and AC Magnetization Properties of Polyion Complex-Coupled Magnetic Nanoparticles

抄録

  Medical applications such as those using magnetic nanoparticles (MNPs) for hyperthermia and magnetic particle imaging (MPI) require suitably designed particles with distinct characteristics. However, it is challenging to develop such particles with a high degree of biocompatibility. In this study, a cationic diblock copolymer (PMPC₁₀₀-b-MMAPTAC₁₀₀: P₁₀₀M₁₀₀) composed of poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC) and poly(3-(methacryloylamino)propyl trimethylammonium chloride) (PMAPTAC) was synthesized via a controlled radical polymerization technique to obtain particles with high biocompatibility and antithrombogenicity. Magnetic polyion complex (PIC) aggregate (M-300/P₁₀₀M₁₀₀) is an aggregate of magnetic Fe₃O₄ nanoparticles (M-300), in which their anionic surface is electrostatically coated with cationic PMPC₁₀₀-b-MMAPTAC₁₀₀ (P₁₀₀M₁₀₀). We investigated the stability of the magnetic PIC aggregate in an ionic solution by evaluating the relationship between the particle diameter and salt concentration. We then estimated the intrinsic loss power (ILP) from the areas of the alternating current (AC) hysteresis loops and measured the AC magnetization of the magnetic PIC aggregate. The peak frequencies from the Brownian relaxation of M-300 and M-300/P₁₀₀M₁₀₀ were 9 kHz and 245 Hz, respectively. When the third harmonic was evaluated for use in MPI, the signal intensity was found to be comparable to that of M-300 in a fixed state.