目的 制备粒径均一、超顺磁性强、性质稳定、免疫活性强并可识别乳腺癌患者外周血循环肿瘤细胞的免疫磁性纳米粒(immunomagnetic nanoparticles,IMNP)。方法 多元醇法合成含有活性羧基基团的超顺磁氧化铁纳米粒(superparamagnetic oxide iron nanoparticles containing reactive carboxyl groups,SMNP-COOH),热重分析法测定SMNP-COOH表面羧基含量,邻二氮菲测定铁含量。在1-甲基-3-乙基碳二亚胺(EDC),N-羟基琥珀酰亚胺(NHS)活化下,采用碳二亚胺偶联法将鼠抗人乳腺珠蛋白(anti human mammaglobin,anti-hMAM)单克隆抗体共价修饰结合至SMNP-COOH表面合成IMNP。透射电镜( transmission electron microscope,TEM)、X射线衍射仪(X-ray powder diffraction XRD)、振动样品磁强计(vibrating sample magnetometer,VSM)、激光散射粒径电位测定仪和邻二氮菲法测定铁含量等方法分别对SMNP-COOH和IMNP进行表征,酶联免疫吸附测定(enzyme linked immunosorbent assay,ELISA)测定IMNP表面抗体活力。结果 X-射线粉末衍射检测表明,SMNP-COOH和IMNP两者特征峰与标准Fe₃O₄的特征峰一致。SMNP-COOH和IMNP的铁含量分别0.205和0.164 mol·L^-1;透射电镜检查提示,SMNP-COOH和IMNP均呈球形或椭球形,透射电镜测定粒径为(13.7±3.6)和(15.4±4.5)nm;流体粒径测定结果表明,SMNP-COOH和IMNP强均粒径和多分散系数分别为23.4,71.2 nm,0.303和0.175;磁学性能研究表明,SMNP-COOH和IMNP均具有超顺磁性,抗体结合可以降低SMNP-COOH的磁性,两者质量饱和磁化强度分别为71.37和67.68 emu·g^-1Fe。ELISA法测定IMNP表面的抗体活力表明,IMNP表面结合的抗体量为93 μg·mg^-1 IMNP。抗-hMAM抗体修饰的IMNP能与乳腺癌细胞株MDA-MB-415具有强的选择性和特异性。结论 成功合成超顺磁性强,能与乳腺癌细胞株发生特异性结合的免疫磁性纳米粒,可用于免疫磁性分离富集乳腺癌患者外周血循环肿瘤细胞(circulating tumor cell,CTCs),从而为乳腺癌CTCs的特异性检测提供更有利的武器。

OBJECTIVE To synthesize immunomagnetic nanoparticles with uniform particle size, strong superamagnetism as well as strong immune activity which can be specifically and sensitively combined with circulating tumor cells in peripheral blood of patients with breast cancer.METHODS Superparamagnetic oxide iron nanoparticles containing active carboxyl groups (SMNP-COOH) were synthesized by polyol methods, thermogravimetric analysis was used to determine the amount of carboxyl groups on the surface of SMNP-COOH, while the content of iron was determined by o-phenanthroline. Mediated by 1-ethyl-3,3-dimethylaminopropyl carbodiimide(EDC) and N-hydroxysuccinimide (NHS), immunomagnetic nanoparticles(IMNP) against human breast carcinoma cell line were constructed by binding the monoclonal antibodies against hMAM with SMNP-COOH. X-Ray diffraction was used to confirm their synthesis,meanwhile,transmission electron microscope (TEM), dynamic light scattering (DLS), and vibrating sample magnetometry (VSM) were applied to characterize their physicochemical properties. The conjugation amount of the antibodies and the activity of IMNPs were evaluated by enzyme linked immunosorbent assay (ELISA).RESULTS X-Ray diffraction showed that the chracteristic peaks of the crystalline powder of SMNP-COOH and IMNP agreed with the Fe₃O₄ standard. The concentration of iron in SMMP-COOH and IMNP were 0.205 and 0.164 mol·L^-1, respectively.TEM showed that both synthesized SMNP-COOH and IMNP were almost spherical or ellipsoidal. The sizes of SMNP-COOH and IMNP were (13.7±3.6) and (15.4±4.5) nm, respectively. Dynamic light scattering(DLS) demonstrated the intensity particle size and polydispersity index (PDI) of SMNP-COOH and IMNP were 23.4 nm and 0.303, and 71.2 nm and 0.175,respectively. VSM results showed that both SMNP-COOH and IMNP had strong superamagnetism, and the saturation magnetization of SMNP-COOH and IMNP were 71.37 and 67.68 emu·g^-1Fe, respectively, which confirmed antibody binding may reduce the magnetism of SMNP-COOH. The ELISA results showed the conjugation amount of antibody was about 93 μg on 1 mg SMNP-COOH by covalent bond. The obtained immunomagnetic nanoparticles (IMNP) which were bound with the hMAM monoclonal antibodies could specifically and sensitively combine with breast cancer cell line MDA-MB-415.CONCLUSION IMNP with strong superparamagnetic property,excellent stability and perfect antibody activity were successfully synthesized, which demonstrate the potential to magnetically separate circulating tumor cells in peripheral blood from patients with breast cancer, thus providing a favorable weapon to accurately detect CTCs in breast tumor patients.