Introduction: Despite the growing interest in the medical applications of magnetic nanoparticles (MNPs), the structural changes of MNP clusters in biological media under static magnetic fields (SMFs) remain poorly characterized. This study investigates how SMF influences the density and shape of MNP clusters in a breast phantom containing tumor cells.
Materials and Methods: Fe3O4 nanoparticles (<50 nm, Sigma-Aldrich) with a magnetic moment of 56.31 emu/g, coercivity of 6.48 Oe, and hysteresis loop area of 350.95 erg/g were visualized in a gelatin-based breast-mimicking phantom with MCF-7 breast adenocarcinoma cells in Dulbecco’s Modified Eagle Medium (DMEM, Sigma) using digital breast tomosynthesis. A Nd2Fe14B disc magnet was used to guide MNP distribution, generating mechanical forces on MCF-7 cells. Quantitative analysis of MNP clusters employed the convex hull method to calculate pixel density and circularity in acquired 3D X-ray images using ImageJ 1.53k (NIH) software.
Results: SMF application increased MNP cluster density from 0.28 ± 0.03 pixel-1 to 0.53 ± 0.04 pixel-1 (p < 0.05). There was a 14% increase in the circularity of MNP cluster formations in response to SMF (0.81 ± 0.02 a.u.) compared with MNPs alone (0.70 ± 0.02), p < 0.05. Estimated magnetic forces ranged from 0.001 to 255.28 pN, which was within the range known to initiate magneto-mechanochemical effects on tumor cells. Remote control of MNP clustering by SMF leads to altered force distributions in the cells, modulating mechanochemical transduction via conformational changes in protein–lipid interactions, ion channels and membrane receptors. This enables theranostic applications, wherein SMFs enhance MNP delivery, imaging contrast, and targeted antitumor effects.
Conclusion: The current study demonstrates that SMF influences the spatial distribution of MNP clusters in a breast phantom with MCF-7 cells, drawing attention to personalized breast cancer treatment strategies based on the magneto-mechanochemical effects of MNPs on tumor cells.
