摘要目的 制备负载油性、水性超顺磁性氧化铁(SPIO)颗粒聚合物纳米囊泡,并观察其表征和MRI成像特点.方法 经多步化学反应得到共聚物聚乙二醇-聚(D,L-丙交酯)(PEG-PDLLA),通过多次乳化及溶剂挥散法使共聚物在水溶液中自组装成囊泡,并分别负载油性和水性SPIO.使用扫描电镜和透视电镜观察负载油性、水性SPIO聚合物纳米囊泡的直径、形态、分布,并用MRT2 mapping软件测量单纯SPIO水溶液、负载油性、水性SPIO聚合物纳米囊泡的T2弛豫率(1/T2).溶液浓度分别取原液、原液的1/2、1/4、1/8、1/16、1/32.结果 负载油性SPIO和水性SPIO聚合物纳米囊泡的的平均直径分别为( 182.2 ±23.9) nm、(191.7 ±28.7) nm.电镜显示油性SPIO均匀地分散于囊泡的中心膜上；水性SPIO以团簇的形式被包裹在囊泡的内腔中.负载SPIO的聚合物囊泡比单纯SPIO水溶液表现更高MRI敏感性.在相同铁离子浓度下,负载水性SPIO聚合物囊泡的T2弛豫率(1/8浓度时为4.60)高于负载油性SPIO聚合物纳米囊泡(1/8浓度时为2.85).结论 负载SPIO聚合物纳米囊泡比单纯SPIO水溶液表现出更高的MRI敏感性,负载水性SPIO聚合物囊泡的T2弛豫率高于负载油性SPIO聚合物纳米囊泡.

abstractsObjective To prepare the polymeric nano- vesicles loaded with hydrophobic and hydrophilic supraparamagnetic ironic oxide (SPIO) and to investigate their physical,chemical and MRI characteristics.Methods The polymeric nano-vesicles were prepared from poly D,L-lactic acid (PDLLA)and poly ethylene glycol (PEG) by a multiple emulsion/solvent evaporation method.The hydrophobic SPIO and hydrophilic SPIO were loaded in the polymeric nano-vesicles respectively.Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to demonstrate the size,distribution and morphous of the SPIO-loaded polymeric nano-vesicles.The MRI T2 relaxivities (1/T2) of water-soluble SPIO,hydrophobic SPIO-loaded and hydrophilic SPIO-loaded vesicles at different concentrations (stock solution,1/2,1/4,1/8,1/16,1/32 of stock solution respectively) were measured by T2 map sequence and T2 mapping software.Results The average diameter of the hydrophobic SPIO loaded polymeric nano- vesicles was (182.2±23.9) nm,compared with (191.7±28.7) nm for the hydrophilic SPIO loaded nano-vesicles.SME and TEM showed that the hydrophobic SPIO particles were uniformly dispersed in the membrane of the vesicle,while clusters of the hydrophilic SPIO particles were loaded in the inner core of the vesicles.The T2 relaxivity rates (1/T2) of water-soluble SPIO at different concentrations were 7.18,4.96,3.02,2.11,1.92 and 1.81,respectively.The T2 relaxivity rates of hydrophobic SPIO-loaded vesicles at different concentrations were 14.45,9.60,4.15,2.85,2.40 and 2.10,respectively.The T2 relaxivity rate of hydrophilic SPIO-loaded vesicles at different concentrations were 9.44,13.02,6.95,4.60,3.13 and 2.53,respectively.Conclusions The SPIO-loaded vesicles are more superparamagnetic than those of water-soluble SPIO at the same concentration of SPIO.The hydrophilic SPIO-loaded polymeric nano-vesicles have a higher MRI T2 relaxivity rate than hydrophobic SPIO-loaded vesicles.