包被材料对磁性纳米粒胶束MRI信号和弛豫效能的影响

Effect of coating materials on MRI signal intensity and relaxivity of magnetic nanoparticles micelles

目的分析不同包被材料对磁性纳米粒(Magnetic nanoparticles,MNs)胶束的MRI信号及弛豫效能的影响。方法对两亲嵌段共聚物聚乙二醇/聚己内酯(PEG-b-PCL)和聚乙烯亚胺/聚己内酯(PEI-b-PCL)包被的铁酸锰(MnFe2O4)纳米粒胶束(PEG-b-PCL-MnFe2O4、PEI-b-PCL-MnFe2O4)行磁共振成像检查,观察不同浓度MNs胶束溶液MRI信号变化规律,测量纳米粒胶束的T1和T2弛豫时间,计算两种包被材料MNs胶束的r1值和r2值,评价不同包被材料对MnFe2O4纳米粒胶束弛豫效能的影响。结果 PEG-b-PCL-MnFe2O4和PEI-b-PCL-MnFe2O4溶液的信号变化规律基本一致,在T2WI和T2*WI,随着浓度的增加,信号强度逐渐降低,PEG-b-PCL-MnFe2O4较PEI-b-PCL-MnFe2O4降低更明显。在T1WI,信号强度先增高后降低,信号达到峰值时,PEG-b-PCL-MnFe2O4和PEI-b-PCL-MnFe2O4的浓度分别为0.2 mmol/L和0.4 mmol/L,浓度相同时,PEG-b-PCL-MnFe2O4较PEI-b-PCL-MnFe2O4的信号低。PEG-b-PCL-MnFe2O4和PEI-b-PCL-MnFe2O4的r2值分别为186.4(mmol/L)-1.s-1和83.3(mmol/L)-1.s-1,r1值分别为0.95(mmol/L)-1.s-1和1.09(mmol/L)-1.s-1,PEG-b-PCL-MnFe2O4较PEI-b-PCL-MnFe2O4的r2值高。结论包被材料对MNs胶束的弛豫效能产生明显影响,相对于PEI-b-PCL,PEG-b-PCL包被的纳米粒胶束具有更强的r2弛豫效能和较弱的r1弛豫效能。

Objective To analyze the effect of coating materials on the magnetic resonance imaging（MRI） signal intensity and relaxivity of magnetic nanoparticles（MNs） micelles.Methods PEG-b-PCL-MnFe2O4 and PEI-b-PCL-MnFe2O4 MNs micelles,which were MnFe2O4 MNs coated with PEG-b-PCL and PEI-b-PCL,respectively,were examined by MRI.The MRI signal intensity of MNs micelles solution with different concentrations was observed,T1 and T2 relaxation time were measured,r1 and r2 values were calculated,and the effect of coating materials on the relaxivity of MNs micelles was evaluated.Results The MRI intensity of PEG-b-PCL-MnFe2O4 and PEI-b-PCL-MnFe2O4 solutions changed almost identically.With the increase of concentration,the signal intensity decreased in T2WI and T＊2WI,and the signal intensity of PEG-b-PCL-MnFe2O4 solution decreased significantly compared with that of PEI-b-PCL-MnFe2O4 solution.The signal intensity of the two MNs micelles solutions increased firstly,and then decreased in T1WI.At the peak signal intensity,the concentrations were 0.2 mmol/L for PEG-b-PCL-MnFe2O4 and 0.4 mmol/L for PEI-b-PCL-MnFe2O4,and the signal intensity of PEG-b-PCL-MnFe2O4 was lower than that of PEI-b-PCL-MnFe2O4 at the same concentration.The r2 value of PEG-b-PCL-MnFe2O4 and PEI-b-PCL-MnFe2O4 was 186.4（mmol/L）-1·s-1 and 83.3（mmol/L）-1·s-1,and the r1 value of PEG-b-PCL-MnFe2O4 and PEI-b-PCL-MnFe2O4 was 0.95（mmol/L）-1·s-1 and 1.09（mmol/L）-1·s-1,respectively.Conclusion Coating materials affect the MRI signal intensity and relaxivity of MNs micelles significantly.