中文摘要：

提出了一种快速对磁性纳米粒子表面羧基化的方法.以氯化铁和氯化亚铁为原料,油酸为表面活性剂,通过共沉淀法制得油酸包覆的亲油性Fe3O4磁性纳米粒子,然后用高锰酸钾进行原位氧化,将覆盖在粒子表面油酸中的C C键氧化成—COOH,从而得到单层羧基功能化的亲水性磁性纳米粒子.利用透射电子显微镜（TEM）、X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）、热重分析仪（TGA）、振动样品磁强计（VSM）和Zeta电位分析仪等对其进行了表征.结果表明,磁性纳米粒子的表面被成功羧基化,粒子的平均直径约为9 nm,饱和磁化值为64.5 A.m2/kg,剩磁和矫顽力近似为零,具有典型的超顺磁性.羧基化磁性纳米粒子可在pH=7～10的水溶液中形成稳定分散的磁流体,保存42 d后无沉淀出现.

英文摘要：

Hydrophilic magnetic nanoparticles have been widely applied in biological sciences.In this work,we proposed a convenient method to synthesize surface carboxylic magnetic nanoparticles.Firstly,hydrophobic magnetic nanoparticles coated with oleic acid were prepared from ferric chloride and ferrous chloride by co-precipitation method,with oleic acid as surfactant.Then the C-C bond of oleic acid coated on the surface of particles was oxidized into —COOH by KMnO4 solution in situ,thereby hydrophobic magnetic nanoparticles functioned by monolayer carboxylic groups were obtained.The magnetic nanoparticles were characterized by transmission electron microscopy（TEM）,X-ray diffraction（XRD）,Fourier transform infrared（FTIR）,thermogravimetric analysis（TGA）,vibrating sample magnetometry（VSM） and Zeta potential analyzer and so on.The results showed that magnetic nanoparticles surface was successfully carboxyl-functioned.The average diameter and the saturation magnetization of the nanoparticles were about 9 nm and 64.5 A·m2/kg,respectively.The remnant magnetization and coercivity of the nanoparticles were nearly to be 0,which demonstrated it was classic superparamagnetic.The carboxyl-functioned magnetic nanoparticles could be dispersed into water to form ferrofluid,which were stable for more than 42 d without precipitation at pH values of 7—10.