BSA-Based Stabilization of Prussian Blue-Coated Manganese Ferrite Nanoparticles for MRI

Objectives: Magnetic nanoparticles are promising candidates for T2-weighted magnetic resonance imaging (MRI), but their physicochemical stability and biological compatibility remain important challenges for biomedical applications. Methods: In this study, amine-functionalized manganese ferrite (MnFe₂O₄) nanoparticles were coated with Prussian blue (PB) and subsequently formulated with bovine serum albumin (BSA). The resulting formulation was characterized using X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, magnetic measurements, dynamic light scattering, molecular dynamics simulations, cytocompatibility assays, and MRI relaxometry. Results: The BSA-formulated nanoparticles were readily redispersed after lyophilization and remained colloidally stable throughout the 6 h observation period in the tested aqueous media. Molecular dynamics simulations demonstrated persistent close contacts between the MnFe₂O₄ surface and BSA residues, supporting stable nanoparticle-protein association. MRI relaxometry showed predominantly T2-weighted contrast behavior, with substantially higher r₂ than r₁ relaxivity. In vitro metabolic activity measurements demonstrated higher relative metabolic activity for the PB-coated formulation than for the corresponding uncoated formulation within the BSA-formulated systems. A pilot in vivo MRI experiment performed in a single mouse demonstrated rapid hepatic accumulation, with a detectable reduction in liver signal intensity within 10 min after administration and persistence of the hepatic signal change at the following-day measurement. Conclusions: These preliminary findings support further investigation of BSA-formulated PB-coated MnFe₂O₄ nanoparticles as a potential T2-weighted MRI contrast platform.