Construction of Hybrid Alginate Nanogels Loaded with Manganese Oxide Nanoparticles for Enhanced Tumor Magnetic Resonance Imaging.

Development of sensitive contrast agents for positive magnetic resonance (MR) imaging of biosystems still remains a great challenge. Herein, we report a facile process to construct hybrid alginate (AG) nanogels (NGs) loaded with manganese oxide (Mn3O4) nanoparticles (NPs) for enhanced tumor MR imaging. The obtained AG/PEI-Mn3O4 NGs with a mean size of 141.6 nm display excellent colloidal stability in aqueous solution and good cytocompatibility in the studied concentration range. Moreover, the hybrid NGs have a high r1 relaxivity of 26.12 mM-1 s-1, which is about 19.5 times higher than that of PEI-Mn3O4 NPs with PEI surface amine acetylated (PEI.Ac-Mn3O4 NPs). Furthermore, the AG/PEI-Mn3O4 NGs presented longer blood circulation time and better tumor MR imaging performances in vivo than PEI.Ac-Mn3O4 NPs. With the good biosafety confirmed by histological examinations, the developed AG/PEI-Mn3O4 NGs may be potentially used as an efficient contrast agent for enhanced MR imaging of different biosystems.