中文摘要：

目的：研究聚集和表面分子吸附对磁性纳米粒子交流磁化率的影响,为发展基于磁性纳米粒子磁化率测量的生物传感方法提供依据。方法：用透射电子显微镜及振动样品磁强计分别对磁性纳米粒子的磁核粒径、磁性特征进行测量,利用实验室自建的交流磁化率测量装置,对在不同聚集状态和表面吸附抗原、抗体等生物分子后磁性纳米粒子的交流磁化率谱进行测量。结果：透射电子显微镜测量表明,实验所用氧化铁纳米粒子平均磁核直径10 nm,但是由于溶液中粒子之间的磁偶极相互作用而以聚集体的形式存在,表现出较大的水动力尺寸及其分布。振动样品磁强计测量表明,氧化铁纳米粒子的饱和磁化强度为61.43 emu·g^-1。交流磁化率谱测量表明,随着氧化铁纳米粒子在溶液中水动力尺寸的增加,即聚集体尺寸的增加,磁化率谱中对应的磁动力学特征频率减小,与理论预示一致。当缓冲溶液中磁性纳米粒子表面吸附IgG以及进一步结合羊抗人IgG后,磁动力学特征频率逐渐降低,这与表面吸附导致的水动力尺寸逐渐增加的结果是一致的。结论：溶液中磁性纳米粒子的聚集状态和生物分子吸附对其交流磁化率谱有较大的影响,主要表现为粒子的水动力尺寸增加所导致的磁动力特征频率发生移动。基于磁性纳米粒子的磁动力特征频率的变化,可望发展成为一种研究磁性纳米粒子表面生物分子相互作用的生物传感方法。

英文摘要：

Objective：To investigate the effect of aggregation and surface molecular adsorption on AC susceptibility of magnetic nanoparticles,which will provide a basis for bio-sensing based on AC magnetic susceptibility measurement.Methods：Using transmission electron microscopy and vibrating sample magnetometer,the magnetic nanoparticles magnetic core size,magnetic characteristics were measured respectively.Using self-built AC susceptibility measuring device,magnetic nanoparticles,with different aggregation states and surface adsorption of antigen,antibody and other bio-molecules,susceptibility spectra were measured.Results：TEM study showed that the magnetic nanoparticles have a magnetic core size of about 10 nm.Because the magnetic dipole interaction between nanoparticles,the particles exist in the form of aggregates and show a larger hydrodynamic size distribution.VSM measurement showed that the saturation magnetization（Ms） was about 61.43 emu·g^-1.AC magnetic susceptibility spectrum measurement showed that with the hydrodynamic size increases of nanoparticles in the solution,that was,the size increase of the aggregates,the characteristic frequency decreases of the AC magnetic susceptibility spectra,which was consistent with the theory.The study also indicated that when magnetic nanoparticles adsorbed IgG and subsequently conjugated goat anti human IgG,the magnetodynamic characteristic frequency gradually decreased,which was consistent with the result of the increase in hydrodynamic size.Conclusions：The magnetic nanoparticle aggregation and surface biological molecule adsorption in solution affect strongly AC magnetic susceptibility spectrum,i.e.,change the magnetodynamic characteristic frequency,resulting from the increase of nanoparticles hydrodynamic size.Based on the magnetic nanoparticles magnetodynamic characteristic frequency changes,so,it is expected to develop into a biological detection method to sense biological molecule interactions on the surface of magnetic nanoparticles.