采用表面活性剂3-氨丙基三乙氧基硅烷(APTES)修饰Fe₃O₄磁性纳米粒子, 经质子化后, Fe₃O₄磁性纳米粒子表面披覆大量的正电荷, 与表面带负电荷的巯基丙酸(MPA)修饰的核壳CdSe/CdS/ZnS量子点(QDs)通过强烈的静电作用而发生组装, 得到兼具磁性和荧光性能的磁性荧光纳米材料. 利用透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、荧光分光光度计和振动样品磁强计(VSM)等测试手段对磁性荧光纳米材料进行表征. 研究表明, 由两种粒子组装的核壳结构复合粒子拥有良好的磁性能和荧光性能.

Nanostructure acquiring multiple functionalities is emerging as a promising example for future functional materials. Magnetofluorescent nanomaterials with rapid magnetic response and highly efficient luminescence reveal a great potential in practical applications, such as susceptive biosensor and targeted optical imaging. Taking the best use of magnetic properties and fluorescent properties of nanoparticles, a kind of nanocomposites was devised through assembling magnetic nanoparticles with fluorescent nanoparticles. To date, some strategies have been developed to build various hierarchical magnetofluorescent nanostructure by assembling quantum dots (QDs) and magnetic nanocrystals, such as encapsulation and one-pot synthesis. Herein, we prepared a kind of magnetofluorescent nanocomposites by a new method based on electrostatic interactions. On the basis of previous works, Fe₃O₄ nanoparticles performed good magnetic properties and the multishell quantum dots (CdSe/CdS/ZnS) showed excellent fluorescent properties. In our work, Fe₃O₄ magnetic nanoparticles were prepared through a high-temperature pyrolysis method and modified by coupling agent 3-aminopropyl triethoxysilane (APTES). After process of protonation, the surface of Fe₃O₄ magnetic nanoparticles was covered with a large number of positive charges. And the multishell quantum dots (CdSe/CdS/ZnS) which were prepared through layer-by-layer self-assembly method were modified by mercaptopropionic acid (MPA). Through deprotonation, the surface of the multishell quantum dots was covered with a lot of negative charges. Induced by intense electrostatic interactions, the modified Fe₃O₄ magnetic nanoparticles were assembled with the modified multishell quantum dots (CdSe/CdS/ZnS) into a type of magnetic fluorescent particles. For rigorous study, the particles were characterized by the means of Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), fluorescence spectrophotometer and vibrating sample magnetometer (VSM). The FT-IR pattern and TEM figures confirmed the desirable core-shell nanostructure. The nanocomposites performed well crystallization from the XRD measurement as to the original nanocrystals. The results of fluorescence spectrophotometer and VSM confirmed the nanocomposites inherited both magnetic properties and fluorescent properties well.