Magnetic parameters evaluation of magnetic nanoparticles for use in biomedical applications

We present a procedure for the comprehensive evaluation of parameters of magnetic nanoparticles (MNPs), such as saturation magnetization, core-size distribution, anisotropy energy constant, and characteristic time for Neel relaxation for use in biomedical applications and fundamental MNPs research. The static magnetization curve of suspended and immobilized MNP samples and the AC susceptibility of immobilized samples were used for the evaluation of these parameters. The magnetic properties reconstructed from the obtained parameters agreed with the experimental results, indicating the accuracy of the estimation procedure. Using the procedure, the parameters of the commercial Resovist MNP sample were evaluated. Then, the Resovist sample was magnetically fractionated into two MNP samples with large and small core sizes, and the parameters of the two fractionated samples were evaluated. It was demonstrated that the parameters of the Resovist sample are given by the volume-weighted average for those of the fractionated samples.