中文摘要：

背景：研究已证明，多个纳米粒簇样聚集或增大纳米粒的粒径可增加纳米粒的饱和磁化强度，但粒径的增大会降低纳米粒在体内的有效循环时间。目的：合成MnFe2O4纳米胶束，检测其应用于磁共振分子影像的可行性。方法：采用高温热解法合成MnFe2O4纳米粒，以聚乙二醇-聚已内酯两亲嵌段聚合物自组装包裹MnFe2O4纳米粒，形成聚乙二醇-聚已内酯-MnFe2O4纳米胶束。对MnFe2O4纳米粒及聚乙二醇-聚已内酯-MnFe2O4纳米胶束的粒径、形态、包被物、铁/锰构成比、分散性等参数进行表征。将不同铁浓度（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）的聚乙二醇-聚已内酯-MnFe2O4纳米胶束或聚乙二醇-聚已内酯-Fe3O4溶液放于EP管中，利用磁共振测量弛豫率。结果与结论：①MnFe2O4纳米粒呈单分散性，粒径约11 nm，Zeta粒径为（11.18±1.72） nm，铁/锰摩尔构成比为2.13∶1；聚乙二醇-聚已内酯-MnFe2O4纳米胶束由十几个到数十个纳米粒聚集呈团状或簇状，粒径为52-86 nm，zeta粒径为（78.8±12.4） nm；②聚乙二醇-聚已内酯-MnFe2O4纳米胶束或聚乙二醇-聚已内酯-Fe3O4的信号变化趋势相似，随着铁浓度的增加，T1WI信号强度先升高后降低；T2WI信号强度逐渐降低，且在T2＊WI信号强度降低更明显；③结果表明，聚乙二醇-聚已内酯-MnFe2O4纳米胶束粒径适中，单分散性好，T2弛豫效能强，有望作为敏感的T2WI对比剂应用于磁共振分子影像。

英文摘要：

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.