Synthesis of MnFe2O4 nanomicelles and its application in magnetic resonance molecular imaging

Yang Hua; Gong Ming-fu; Zou Li-guang; Zhang Song; Shu Tong-sheng; Zhou Pei-hua

doi:10.3969/j.issn.2095-4344.2016.47.014

Abstract：BACKGROUND:Studies have shown that the saturation magnetization of nanoparticles can be increased by increasing of particle size of nanoparticles or cluster-like aggregation of multiple nanoparticles. But the increased particle size can reduce the cycle time of nanoparticles in the body. OBJECTIVE:To synthesize MnFe2O4 nanomicel es and explore the feasibility of its application in magnetic resonance molecular imaging. METHODS:MnFe2O4 nanoparticles were synthesized using thermal decomposition method and self-assembled with polyethylene glycol-polycaprolactone amphiphilic diblock copolymers (PEG-PCL) to construct PEG-PCL-MnFe2O4 nanomicel es. The characteristics of the MnFe2O4 nanoparticles and nanomicel es were tested. Then, MnFe2O4 nanoparticles and nanomicel es at different iron concentrations (0, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.6, 0.8 mmol/L) were placed into EP tubes. Relaxation rate of the nanomicel es were measured using magnetic resonance scanner. RESULTS AND CONCLUSION:(1) MnFe2O4 nanoparticles appeared as round under transmission electron microscopy. The size of nanoparticles was 11 nm with good monodispersion. The Zeta-particle size was (11.18±1.72) nm. The molar ratio of Fe/Mn was 2.13:1. The size of PEG-PCL-MnFe2O4 nanomicel es ranged from 52 to 86 nm, with a mean Zeta-particle size of (78.8±12.4) nm. (2) The signal intensity (SI) change of PEG-PCL-MnFe2O4 nanomicel es and PEG-PCL-Fe3O4 nanomicel es shared similar trend according to iron concentration. With the increasing of iron concentration, SI first increased and then decreased in T1WI, and it gradual y decreased in T2WI and T2*WI. The SI changes in T2*WI were significantly stronger than that in T2WI and T1WI. Taken together, our results show that PEG-PCL-MnFe2O4 nanomicel es are expected to perform as a sensitive contrast agent used in T2WI as their moderate particle size, good monodisperse and strong T2 relaxation.