Ultrasmall Ferrite Nanoparticles Synthesized via Dynamic Simultaneous Thermal Decomposition for High-Performance and Multifunctional T1 Magnetic Resonance Imaging Contrast Agent

Large-scale synthesis of monodisperse ultrasmall metal ferrite nanoparticles as well as understanding the correlations between chemical composition and MR signal enhancement is critical for developing next-generation, ultrasensitive T1 magnetic resonance imaging (MRI) nanoprobes. Herein, taking ultrasmall MnFe2O4 nanoparticles (UMFNPs) as a model system, we report a general dynamic simultaneous thermal decomposition (DSTD) strategy for controllable synthesis of monodisperse ultrasmall metal ferrite nanoparticles with sizes smaller than 4 nm. The comparison study revealed that the DSTD using the iron-eruciate paired with a metal-oleate precursor enabled a nucleation-doping process, which is crucial for particle size and distribution control of ultrasmall metal ferrite nanoparticles. The principle of DSTD synthesis has been further confirmed by synthesizing NiFe2O4 and CoFe2O4 nanoparticles with well-controlled sizes of ∼3 nm. More significantly, the success in DSTD synthesis allows us to tune both MR and b...