柠檬酸修饰的磁性Fe_3O_4纳米颗粒制备及其弛豫性能

摘要

采用共沉淀法制备了柠檬酸修饰的磁性Fe3O4纳米颗粒。通过改变反应过程中柠檬酸的量,研究柠檬酸加入量对纳米颗粒粒径的影响。通过透射电子显微镜、红外、热重、震动样品磁强计等表征手段对制备的磁性纳米颗粒进行表征。结果显示,随着柠檬酸加入量的增加,纳米颗粒的粒径减小,单位质量的颗粒表面包覆的柠檬酸量增大,比饱和磁化强度降低。最后研究了它们的磁共振弛豫性能,发现随着纳米颗粒粒径的逐渐减小,纵向弛豫率和横向弛豫率都显著减小,表明柠檬酸小分子可以成为磁性纳米颗粒造影剂合成有效的调控分子。%Citric acid capped magnetic Fe3O4 nanoparticles were prepared by coprecipitation method.The influence of citric acid on the size of magnetic nanoparticles was investigated by changing the amount of citric acid added.Characterized by transmission electron microscopy（TEM）,Fourier transform infrared spectroscopy（FTIR）,thermo-gravimetric analysis（TGA） and vibrating sample magnetometry（VSM）,it was demonstrated that the size and saturation magnetization of Fe3O4 nanoparticles decreased with the increase of citric acid,which led to an increase of the surface coating of citric acid.Finally,the relaxation properties of Fe3O4 were studied.It was found that both longitudinal relaxation rate and transverse relaxation rate were reduced as the size of nanoparticles decreases which showed that citric acid is an effective modifying small molecule for iron oxide nanoparticles.