Antifouling Manganese Oxide Nanoparticles: Synthesis, Characterization, and Applications for Enhanced MR Imaging of Tumors.

Antifouling manganese oxide (Mn3O4) nanoparticles (NPs) were synthesized by solvothermal decomposition of tris(2,4-pentanedionato) manganese(III) in the presence of trisodium citrate, followed by surface modification with polyethylene glycol and l-cysteine. The as-prepared nanoparticles have a uniform size distribution, good colloidal stability and good cytocompatibility. The modification of l-cysteine rendered the particles with much longer blood circulation time (half-decay time of 28.4 h) than those without l-cysteine modification (18.5 h), and decreased macrophage cellular uptake. Thanks to desirable antifouling property and relatively high r1 relaxivity (3.66 mM-1 s-1), the l-cysteine-modified Mn3O4 NPs can be used for enhanced tumor magnetic resonance imaging applications.