Novel and efficient MR active aqueous colloidal Fe3O4 nanoassemblies

This work demonstrates a new class of magnetic resonance (MR) active aqueous Fe3O4 magnetic nanoparticle nanoassemblies (Fe3O4 MNNA) of similar to 40 nm size comprising similar to 6 nm particles. They exhibit enhancement in T-2 MR contrast as compared to 6 nm isolated counterparts (Fe3O4 MNP) and commercial contrast agent, ferumoxytol. This significant improvement in the T-2 MR signal arises from the synergistic magnetism of multiple Fe3O4 nanoparticles assembled in Fe3O4 MNNA. These nanoassemblies also show better colloidal stability, higher magnetization, good specific absorption rate (under external AC magnetic field) and cytocompatibility with cells. Further, the functional groups (-NH2) present on the surface of Fe3O4 particles can be accessible for routine conjugation of biomolecules through well-developed bioconjugation chemistry. Specifically, a new MR active colloidal amine-functionalized Fe3O4 nanoassembly with enhanced T-2 contrast properties has been fabricated, which can also be used as an effective heating source for hyperthermia treatment of cancer.